Note: Descriptions are shown in the official language in which they were submitted.
ilZ5915
Background of the Invention
Field of the Invention
.
This in~ention relates broadly to electro-optical
I ga~ing methods and systems. More particularly, this inven-
,I tion relates to an electro-optical method and system ~or
~aging one or more dimensions of an ob~ect either at a
j stationary position or at various peripheral positions to
determine the profile of the ob~ect. The invention may be
¦¦ used to determine one or two lateral dimensions and lateral
10 ! pro~ile o~ a moving hot bar during bar rolling in a steel
! mill as is disclosed herein. Simila~ly, the invention may
be used to gage one or more dimensions and profile of other
I shaped objects and in other environments as well. In addition,
¦I the invenkion may be used to determine, and pIot if desired,
15 1¦ a gaging system histogram.
!l
Description of the Prior Art
il Generally, in steel mills where hot round bars are
Il rolled, product~vity demands require that a variety o~ bars
¦I be rolled at speeds of up to 1219 m./min. ~4000 ft./min.)
and sizes of up to 7.62 cm. (three inches) in diameter while
the bar rolling temperature is about 930C. (1700F.).
~urther demands require that the speci~ications on ~inished
cold bar size and out-o~-roundness be within one-half
existin~ commerci.al tolerances. In order to meet these
requirements, a computer-controlled rolling process must
be implemented that will combine order data with operating
measurements to produce mill control signals that will
maximize productivity while minimizing, or desirably
¦ eliminatin~, o~-specification product.
'~
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~lZ59~5
Some o~ the operatlng data u~ed ln mlll *ontrol
computer Galculat~on5 and re~erred to hereln are: de~lred
I bar diameter, or aim sige; aim ~lze ~ull~and halr-commercial
¦Itolerance~; and bar grade, or percent carbon compo~itlon
5 ¦1 of the bar to be ro~led. Some Or the operat~ng mea~urement~
" mentloned above and o~ particular importance are: actual bar
;¦ diameter, or bar size; actual bar lateral pro~lle~ or bar
llprofile~ and a hlstogram of bar slze meaAuremen~. Another
¦¦ operating mea~urement i8 bar temperature~ a parameter used
10 1 to correct hot bar ~hrlnkage ln bot}l bar mea~urement and
, computer control a~pect~ o~ mlll operation.
In order tha~ the mill control computer may be
programmed to meet the ~trlct requirementa of mlll speed,
i bar ~ize and slze hal~~olerance~, lt 18 deslrou~ that all
15 l operating mea~uremen~s have the ~ollowlng characterlstic~.
Bar ~ize mea~ur ments be made when the bar vlbrate~ in a
l lateral orbit whiIe movln8 lon~itudlnally durlng rolling: be
¦I made at repetltive rates o~ about 300 H3.; have a resolution
~ of O.0127 mm. (.0005"); have an ab~olute accuracy equlvalent
120 ¦ to one-quarter commerclal tolerance; maintain a high de~ree
:of rellabllity; all mea~urement~ made under the ~evere
environment normally pre~ent in a steel rolling mill. Bar
temperature mea~uremer~ hould have similar chara¢teristic~.
A hlstogram Or bar mea~urements 1~ also provided by the
~ystem.
Several types Or electro-optlcal ga~in~ 3y~kems
are ~ailable to mea~ure bar ~l~e. One early type o~ bar
3ize gaging ~ystem operates on the ~el~-illumlnatlon principl~
in whlch chopped inrrared radlatlon from the hot bar i8
~5~5
:,
imaged through a lens onto an infrared detector. Elementary
edge-detection circuitry was used in an attempt to de~ine
raw detector pulses in relation to bar edges.
, Three more recent electro-optical systems applicable
to bar size measurements operate on the principle of back-
lighting a test object to be measured and imaging a shadow
of the ob~ect through a lens onto the f'ace of an electronic
camera. In one such gaging system, a scanning laser beam
Ililluminates the test object and the lens system focuses the
¦ob~ect shadow onto a phototransistor. In a second such
gaging system~ a stationary light source of fixed intensity
illuminates the test object and the lens system focuses
~the ob~ect shadow onto an electronically scanned image
l¦orthicon tube having two-axis unidirectional scanning. In
1l the third such system, the image orthicon tube is ~eplaced
llby a self-scanning photodiode array.
1; The photoresponsive device in each of the three
Iback-lighted gaging systems generates a raw camera pulse
! having a width that approximates the object dimension
;¦between shado~ edges. Raw camera pulses are processed in
i edge detection circuitry having either plain differentiators
or gated differentiators which further attempt to more
closely define camera pulse width in relation to the obJect
Idimension.
Two additional types of' electro-optlcal gaging
systems are available which combine the above f'eatures to
¦measure bar lateral profile. One type of profile gaging
system combines two self-illuminated cameras fixedly disposed
orthogonally perpendicular to the bar mill pass l~ne. This
4_
l.
system in fact produces only two bar diameter measurements
ilgoo apart but not bar profile measurements. The other type
¦of electro-optical bar profile gaging system incorporates
l~two back-lighted cameras mounted orthogonally on a scanner.
,¦whereby two bar dlameter measurements and a scanner position
measurement are indicated separately and/or recorded on a
multichannel recorder during peripheral scanning of the bar.
Each of the foregoing prior art-electro-optical
,Ibar size and bar profile gaging systems has met with varying
¦degrees of success in certain types of installations. How-
ever, none o~ these gaging systems is entirely satisfactory
to use as a bar dimension and profile gaging system in the
environment of a contemporary high-speed hot steel bar
rolling mill. Such gaging systems fail to meet the fore-
15 ~ going measurement requirements for one or more of thefollowing reasons.
jl Difficulties with prior art gaging systems are
I first, the object to be measured must be confined to a given
- !position in the camera field-of-view. Second, inability to
'Iprovide sufficient camera speed-of-response and/or camera
¦resolution. Th~rd, inability to meet system accuracy at
high repetition rates because considerable sw~tching noise
occurs at such measuring speeds and differentlator noise is
l also particularly troublesorne. In additlon, some environ-
25 l mental electrical noise is present in varying degrees which
¦further compounds the problem of making definitive bar
¦ measurements at high speeds and high reliability. Fourth3
inability or insufficient capability to correct for such
~error souroes s optical and electronic nonlinearities, all
-5-
5~3~5
of which af~ect gaging system accuracy. Fifth, instability
which causes drift în system calibration. Sixth, inability
to provide a meaningful plot and display of cold bar diameters
,, I
i and profile information at various peripheral positions to
1, either a rolling mill operator or a rolling mill control
i computer. Seventh, inability to provide a bar gaging system
histogram. Eighth, inability to compensate or correct size
for distortion resulting ~rom high frequency lateral vibration
of the bar.
Summary of the lnvention
A main obJect of this invention is to provide an
improved electro-optical gaging method and system.
One other object o~ this invention is to provide
an improved electro-optical gaging method and system which
5 ll has a high response speed, a high repetition rate of measure-
il ment, a high accuracy, a high stability and/or a high
Il reliability in the environment of a contemporary high-speed
j¦ hot steel bar rolling mill.
Another obJect of this invention is to provi~e an
20 ¦ improved electro-optical gaging method and apparatus which
l permits accurate measurement of an object when placed at
i any position in a camera field-of-view, inclucling while the
obJect is vibrating in an orbit lateral to longitudinal
~I movement o~ the object.
25 ~ Another object o~ this invention is to provide an
l improved electro-optical gaging method and system which
! determines both object size and object variable position in
a camera .ie d-of-vlew.
S91S
Still another obJect of this invention is to
Iprovide an improved electro~optical gaging method and system
¦which processes a camera signal to remove noise comb~ned
llwith an object size pulse in the camera signal, thereby
5 ! permitting precise definitions of the ob~ect size pulse and/or
~object position in the camera field~of-view.
Yet another ob~ect of this invention is to provide
¦an improved electro-optical gaging method and system which
¦corrects camera ob~ect size signals for optical and electronic
llnonlinearities and/or other sources of error.
! A further object of this invention is to provide an
improved electro-optical gaging method and system which plots
lland displays and/or records one or two orthogonal dimensions
: f', of ~ an object and/or the object's profile at one or more
~` 1 15 I peripheral positions of the object.
Still a further obJect of this invention is to
provide an improved electro-optical gaging method and system
j which plots the profile of an object and displays and/or
1l records the plot overla~d on one or more commercial tolerance
20 1, references of the object.
Another object of this invention is to provide an
¦¦ improved electro-optical gaging method and system which
¦ plots and displays and/or records one or more histograms of
the gaging system.
A final ob;ect of this invention is to provide an
l improved electro-optical gaging method and system which plots
I a profile of an obJect and/or a gage histogram suitable for
use by a computer controlled process.
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I
¦ The foregoing objects may advantageously be
attained for use in a hot bar rolling mill~ for example,
by a computerized electro-optical system for gaging either
~ione- or two-orthogonal dimensions of a moving and vibrating
,Ihot bar either at a stationary position or at various
peripheral positions. One or more back-lighted electronic
camera heads are used and these are mounted 90 apart on
a scanner for two dimensions being gaged. Each camera head
is provided with electronics which include camera AGC and
10 1 a common digital bidirectional sweep generator for one-axis
i scan of each camera simultaneously. Additional electronics
process a bar shadow pulse in pulse edge-detection circuitry
¦ having an autocorrelator to remove noise. Other electronics
¦ include a digital accumu~ator which provides a digital bar
~ size and bar position-in-field-of-view signals.
Each camera's bar size and bar position signals,
a scanner position signal, bar temperature and other signals
are asslmilated by a digital computer which is programmed to
perform the ~ollowing functions either off-line or on-line.
First, correct each bar size signal by digitally compensating
for field-of-view errors, other optical and electronic non-
linearities, bar temperature and other sources of errors,
thereby providin~ highly accurate bar diameter measurements
anywhere in the f`.o.v. Second, calibrate the gage off-line
and automatically recalibrate the gage on-line to offset
calibration drift and slope errors~ rrhird~ either permit
manual operation or automatically control scanner drive and
incremental digital storage of corrected bar diameter
measurements for each camera during scanning. Fourth,
3o ~acilitate interaction with CRT and printing terminals to
~ llZ59~S ~
I
I
I indicate and/or record: (a) each camera~s bar diameter
measurement anywhere in the scanning field; (b) using stored
¦bar diameter data and operating data header, plot bar profile
~deviation ~rom aim gage where the plot is overlaid on full-
!¦and half-commercial tolerance references; and (c~ a histogram
or each gage and a gage difference histogram. The computer
¦¦is adapted to communicate profile and histrogram data to a
¦ rolling mill control system when requested by the control
j system.
'~
I lO ¦ Brief Description of the Drawin~s
,- ~ i - _
¦ FIGURE l is a block diagram of an overall computer
;~ ¦ized electro-optical system for gaging one dimension of one
¦embodiment of thi6 invention.
¦ FIGURE lA is a block diagram of the overall
computerized electro-optical system for gaging two dimensions
which includes dual cameras on a scanner for determining
lateral pro~ile and shows a second embodiment of this
invention. The scanner may also be used with the FIG. l
, embodiment.
FIGURE 2 is a diagram of a bar cross-section
showing maximum and minimum tolerance limits in dotted
circles~ and lncludes a four-plane overlay related to bar
profile orientation.
FIGURE 3 is a computer printout of bar profile
deviation vs. scanner angular position in relation to the
four-plane overlay of FIG. 2 produced in the FIG. lA
embodiment, and includes an operating data header. A
similar printout of bar profile may be achieved with the
FIG. l embodiment using the scanner shown in ~IG. lA.
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FIGURE 4 is a block diagram of camera electronics
for each camera head of the one and two camera systems shown
. in the FIG. 1 and lA embodiments.
FIGURE 5 is a sectional view of a masked photo-
Icathode used in an image dissector tube used in the FIG. 4camera electronics.
FIGURE 6 is a cross-sectional view of the masked
photocathode shown in FIG. 5.
FIGURE 7 is a block diagram of a bidirectional
sweep generator used in the camera electronics shown in
FIG. 4.
FIGURE 8 is a timing diagram of pulses generated
by the bidirectional sweep generator, master clock, window
pulse generator, and AGC blanking circuits shown in the
camera electronics of FIG. 4.
FIGURE 9 ls a block diagram of the camera pulse
processor used in the camera electronics shown in F:[G. 4.
FIGURE 10 is a block diagram of an autocorrelator
u~ed in the camera pulse processor shown in FIG. 9.
FIGURE 11 is a timing diagram of various raw
camera signal, differentiator, autocorrelator and bar pulses
occurring ln the pulse processor shown in FIG. 9~
FIGURE 12 is a circuit diagram of a P.M. (photo-
multipller tube) AGC (automatic gain control) circuit
shown in a camera self-balancing measuring loop incorporated
in the camera electronics shown in FIG. 4.
~ FIGURE 13 is a block diagram of a bar size and
I position accumulator used in the camera electronics shown
in FIG. 4.
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~25~1~
FIGURE 14 is a b10ck diagram of the computer
shown in the one-dimension gaging system shown ln the
FIG. l embodiment and includes references to computer
l~programs associated therewith.
~ FIGURE 14A is a block dlagram of the computer
shown in the two-dimension gaging system having a scanner
l shown in the FIG. lA embodiment and includes references to
I ¦ computer programs associated therewith. The profile and
position programs may also be used for scanning in the
FIG. l embodiment.
FIGURE 15 is a computer ~ISC MAP for both FIG. l
and lA embodiments.
~¦ FIGURE 16 is a computer CORE MAP for the FIG. l
embodiment.
15 l FIGURES 16A and 16B are computer CORE MAPS for the
FIG. lA embodiment.
FIGURE 17 is a typical histogram table printout
I for use în either the FIG. l or lA embodiments of the present
invention.
2C FIGURE 18 is a typical profile table used in
printing the FIG. 3 profile of FIG~ 3 in the FIG. lA embodi-
ment of' the present invention.
FIGURE 19 is a typical flow chart showing the
¦ computer in F'IG. l and lA cornmunicating with a control system
whlch utillzes one or two hlstogram tables of' the present
lnvention as needed in either of the FIG. l or lA embodi-
ments, and further includes a profile table for use in the
FIG. lA embodiment.
L2~ 5
ll
.
Description of the Preferred Embodiments
One-Dimension Gaging System
Referring now to the drawings, particularly
FIG. 1, there iS shown a computerized electro-optical system
Ifor gaging one bar dimension which has a back-lighted camera
mounted in a hot steel bar rolling mill. The gaging system
,measures the diamter of bar 10, for example~ at one lateral
position fixed beyond the exit side of roll stand 11. As
explained below, the bar diameter signal is fed to a computer
which plots the lateral dimension of bar 10. Ultimately,
Ithe bar diameter data is displayed, recorded and transmitted
to a rolling mill control system which uses this data to set
;¦the lateral gap of the rolls in stand 11 to establish the
jaim si~e of bar 10.
!I More specifically, light box 30 is located opposite
electronic camera head 31 so that when bar 10 intercepts
light from box 30 a bar shadow having a width proportional
to bar diameter at a lateral position will be imaged on
electronic camera head 31. A typical arrangement of a back-
Ijlighted camera head is shown in FIG. 4 and described below.
Light box 30 is arranged to produce a light sourceperpendicular to bar 10 larger than the large8t size bar 10
¦,to be gaged in the camera field-of-view. For example, the
,~camera field-of-view referred to below ls 7.62 cm. (three
1~
¦linches) and the light source used therewith is 10.16 cm .
j~four inches). In addition, the wavelength and intensity of
light box must be compatible with the sensitivlty oharacter-
¦ istics of electronic camera head 31. Typically~ blue light
l from a D.C. fired fluorescent light source is preferred for
~the electronic camera head described below.
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The shadow of bar 10, together with excess light
beyond bar 10 edges directed from back light box 30, causes
electronic camera head 31 to generate a camera signal. This
signal consists of a raw camera pulse mixed with noise which
is fed over wire 34 to first camera electronics 35. As
; ~Idescribed below in connection with FIG. 4, the camera signal
is processed to remove the noise and produce digital bar
; size and bar position signals which are fed over cable ~6
I!to computer 27. Gage enable and other signals are fed over
l,cable 37 ~rom computer 27 to camera electronics 35.
Computer 27 in the present electro-optical bar
gaging system also recelves bar 10 aim size digital signals
from thumbwheel selector 42 by way of cable 43. Aim size
signals, exemplified as 4.445 cm. tl.7500 inches)~ are used
~Ito determine bar 10 size deviation and other purposes
described be~ow. In addition, computer 27 also receives a
bar 10 composition digital signal from thumbwheel selector
44 by way of cable 45. Composition signal, which is exemplified
as 0.230% represents percent carbon in the bar 10, is used as
I a factor in correcting hot bar 10 size for shrinkage and other
purposes described below. Further~ computer 27 also receives
appropriate order data signals, including date, time and size
~tolerances for bar 10, from source 46 by way of cable 47.
I Alternatively, any one or all of the aim size signals, com-
25 11 position signals, and other data signals may be supplied by
a control system directly associated w~th rolling bar 10,
depending upon the preference of the bar gaging system user.
In order to make temperature corrections to the
diameter measurements of moving hot bar 10, a Land Co. optical
. Il
i
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llZ59:L5i
pyrometer head 48 is provided ad~acent scanner 12 and
aimed at moving hot bar 10. Optical pyrometer head 48 ls
; adapted to generate a high-response raw tempera~ure signal
which is fed over cable 49 to Land Co. pyrometer electronics
50. The raw temperature signal is corrected by scaling and
linearizing circuits in pyrometer electronics 50 and the
corrected temperature signal, exempli~ied as 1670F. ~910C.),
is fed over cable 51 to digital indicator 52. In addition,
I the corrected temperature signal is fed over cable 53 to
I computer 27 where it is used to compensate for hot bar 10
shrinkage.
Installation probIems may preclude a Land Co.
optical pyrometer head 48 and pyrometer electronics 50 from
providing a corrected temperature signal to computer 27 and
indicator 52 with desired accuracy and rate of response~ If
such is the case, an alternative to the Land Co. pyrometer
;l arrangement may be to replace it with an optical field
scanning pyrometer system is disclosed in U.S. Patent No.
4,015,476 which issued April 5, 1977 to J.J.Roche et al,
20 , titled 'iScanning Pyrometer System". Briefly, the optical
field scanning pyrometer system consists of a rapldly
oscillating mirror mounted in a pyrometer head and aimed at
j a fleld-of-view through which hot bar 10 will travel. The
Il hot bar is lmaged through a slit and onto a high-response
25 1,1 infrared detector in the pyrometer head. The lnfrared
; I detector Eeeds a peak ~etector and sample--and-hold circuits
to measure and store a nonlinear signal of bar 10 temperature.
¦¦ The stored nonlinear signal may be fed over cable 53 to
!l
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,, ., .
computer 27 where lt must be scaled an~/or linearized. The
stored temperature sigrlal is updat~d every scan of the
.
oscillating m~rrorj f~r example every 20 ms., by a busy-ready
fl~g pulse f-ed over dotted-line cable 54. In add~tion, the
'stored tempera~ure is scaled and lineari~zed with less frequent
up-datin~ arld may be fed to bar temperature indicator 52.
'Prov'isions are made for adjusting fieId scanning frequency
'and width of fiel-d-of-vlew to suit a variety"o~ installations.
:' ' ' ' ................................ . - ` i
One other feature of the present bar ~aging system
`I ~la lis an automatia recalibration system. As de~Gribed below,
this feature is initiated each time the traillng end of hot ~;
bar 10 is detected leaving mill rolls 11. For this relason,
hot metal dete~ctor 55 detects the presence and absence of
hot bar 10 and feed-s a corresponding signal over wlre 56
to hot metal detector electronics 57. A presence/absence
signal is fed over cable 58 to computer 27 where it initiates
,
lthe automatic recalibration system mentioned above.
,1
A11 camera signals, aim size signal, composition
signal, other signals, temperature signal and hot metal
~ 20 'presence/absenGe signal fed over respective cables 36, 43,
; 'l45~ 47, 53 and 58 are assimilated by computer 27 to perform
'a variety of ~unctions under control of a group of computer
of.~-line and on-llne programs referred ~,o below. One of
llthese functions is to feed bar diameter data, bar deviation
;25 'Idata overlaid on commercial tolerance references ~rom computer
l~27 over cable 59 to CRT (display) terminal 60, and to accept
I interaction between a standard keyboard on terminal 60 and
computer 27 by way of cable 61.
i~
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~Z~ii9~1LS
, . ,
Another function of computer 27 is to feed
bar diameter data and operating header data from computer 27
over cable 62 to printing terminal 63 3 and to accept inter-
actions between a standard keyboard on terminal 63 and
,cornputer 27 by way of cable 64. Printing terminal 63 pro-
duces printout 65 such as a data log. Still another function
of computer 27 is to feed bar 10 diameter data and a gaging
'system histogram over cable 66 to control system 67 in ,
'response to corresponding request signals fed back to
computer 27 by way of cable 68.
Turning now to FIG. 2, there is shown a cross-
sectional diagram illustrating the lateral profile of bar
10. Dotted circular lines 69 and 70 are illustrative of
maximum and minimum standard commercial tolerances for aim
15 'size diameter. Bar aim size is 4.450 cm. (1.7500 inches)
,for illustrative purposes. Other features of FIG. 2 will be
~¦ described below with reference to the FIG. lA embodiment.
~ It should be noted that the display on CRT terminal
1 60 is substantially the same as computer printout 65. Thus~
~ , .
- 20 I CRT terminal 60 displays bar diameter information in a form
that is unique and quite useful to an operator of the bar
gaging system as well as an operator of a rolllng mill where
~the bar gage is used.
.
ll E tronic Camera Head
Il
1~ A typical back-lighted electronic camera head used
liin the FIG. 1 electro-optical bar gaging system is shown in
¦¦FIG. 4 as camera head 31 placed along an optical axis on the
opposlte side of bar 10 from light box 30. This arrangement
I . '
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illuminates field-of-view 80 and produces bar shadow 81 that
varies vertically proportional to the lateral dimension
between hot bar edges 82, 83. An end view of hot bar 10
makes it appear stationary but in actual practice bar 10
'vibrates in orbit 84 while travelin~ longitudinally at
speeds up to 1219 m./min. (4000 ft./min.). For this reason,
hot bar shadow 81 not only varies vertically proportional to
bar size, but is also dlsplaced horizontally and vertically
~within the confines of about a 7.62 cm. ~three inch) diameter
1~10 I~bar orbit 84. This phenomenon requires a larger field-of-view~ ¦
8n than does a stationary bar, thereby increasing the problems
of precision bar measurements.
Because the bar~shadow 81 varies vertically and
its position varies both horizontally and vertically, camera
, :
Ihead 31 is provided with telecentric lens system 85 which is
designed to admit only parallel light rays with a focal
~ ~ ,plane extending from at least the nearest horizontal edge
I of bar orbit 84 to at least the farthest horizontal edge
~1 of bar orbit 84. This is accomplished by seven-element lens
:: 11
! 86 havin~ a 10.16 cm. (four inch) field-of-view 80 ~ithin
which 7.62 cm. ~three inchj bar orbit 84 is centered vertically.
Other properties of lens 86 include an image size reduction
of 1:2 and a telecentric lens stop 87 having a very narrow
horizontal optical aperture 88 through which bar shadow 81
; passes. Transmission of bar shadow 81 ls limited by optical
l,l fllter 89 to pass only blue light from light box 30~ thereby
1~ eliminating undesirable effects of other light sources in
~he f~eld-of-view which have different wavelengths.
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Accordingly, telecentric lens system 85 produces
a horizontally-oriented bar shadow 81 that ~aries vertically
between bar edges 82, 83 and remains sharply in focus while
bar 10 vibrates in orbit 84. Bar shadow 81 is the same size
;l along the optical axisg but as it is displaced vertically
il away from the optical axis in either dlrection it becomes
larger according to a nonlinear function. This phenomenon
is caused by a combination of electronic, coil and lens
~ nonlinearities and is referred to as field-of-view error
10 l¦ which will be corrected by computer 27 as described below.
Bar shadow 81 trans~itted by telecentric lens
system 85 is imaged upon image responsive device 90 which
. I
is capable of being scanned at 300 Hz., has a resolving power
of at least 1 part in 10,000~ and has a high sensitivity to
blue l~ght. Preferably, device 90 is an image dissector
¦¦ (I.D.) tube having photocathode electrode 91 with a central
¦1 image translating area which receives the bar shadow 81
~ image. Photocathode electrode 91 is located behind a light-
¦ transmitting face in the drift section of I.D. tube 90.
,
I Photoelectrons emitted by photocathode electrode 91 are
focused by external means to pass through electron aperture
92 so they can enter the photomultlplier (P.M.) section of
image dissector tube 90. Preferably, device 90 is an ITT Co.,
U.S.A., high resollltion image dissector tube No. F4052RP.
Camera head 31 also lncludes cylindrical deflection
and focus coil assembly 93 surrounding the cylindrical body
of image dissector tube 90. Coil assembly 93 includes
separate Y-axis and X-axis deflection coils and a focus
llZ5915
,, .
coil, each energized from separate external sources. Standard
mu metal shielding surrounds the exterior cylindrlcal wall
of coil assembly 93, thereby providing ef~ective shielding
against radial magnetic fields. A preferred coil assembly
93 designed for use with the aboYe noted I.D. tube g0 is
Washburn Laboratory, Inc., U.S.A., No. YF2308-CC3C.
Il Occasionally, the standard mu metal shielding in
;, the Washburn Laboratory, Inc. coil assembly 93 may not
provide enough shielding against~both radial and axial
, magnetic field sources. For example, when I.D. tube 90
ls operating at a high sensitivity ievel and electrical
equipment generating strong magne~ic fields located near
the gage is moved, the I.D. tube 90 output may change. If
this condition is encountered in practice, an alternative
- 15 l solution exists which requires modifying the Washburn standard
mu metal shielding to improve the attenuation of axial
magnetic fields. Essentially, this involves extending the
standard Washburn cylindrical mu metal shield axially toward
lens system 85 and closing down the end at filter 89, except
~; 2~ 1I for an optical aperture to image bar shadow 81 onto photo-
cathode electrode 9l in tube 90. Additional axial magnetic
il field attenuation may be achieved by a second cylindrical
mu metal shield surrounding the extended standard shield.
Il Moreover, the standard coil shield may be used without
extension, but axial field attenuation may be achieved by
adding a second and possibly a third cylindrical mu metal
shield extending axially as in the ~irst instance.
~¦ Still referring to FIG. 4, the present electro-
optical bar gagin~ system may experielce other calibration
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g~ l
i!
drift and variations in optical, image dissector tube, and
other electronic no~llnearities inherent in the bar gaging
system. These drift and variable gaglng conditions may be
identified by providing on-line calibration checks and
isubsequently correcting ~he calibrated bar signals as described j
below. These calibration checks are made possible by modi~ying
image dissector tube 90 to provide a masked photocathode
electrode 91 as shown in FIG. 5.
! i
I As can be seen in FIG. 5, masked photocathode
,1 1
1 electrode 91 includes patterned image non-translating areas
adjacent image translating areas. More specifically~
calibration masks 94, 95 are made by selectively depositing
the usual photoresponsive material of photocathode electrode
Il 91 onto image transmitting glass face 96 using a precision
15 ,I mask to form the calibration reference patterns. For example,
calibration mask 94 may consist of a single 6.35 mm.
(0.250 inch) wide mask centered on the right side o~ photo-
11
cathode electrode 91. Calibration mask 94 is referred to as
¦l "right mask" and may be used for on-line checking of bar
¦!
20 ! gaging system calibration drift under RTMASK computer program
¦ described below. Calibration mask g5 may consist o~ five
l 2.54 mm (0.100 inch) wide masks spaced 2.54 mm. (0.100
I inch) apart on the left side of photocathode electrode 91.
Calibration mask 95 is re~erred to as "left mask" and may be
25 ~ used for on-line checking of variations in bar gaging system
¦ optical and electronic nonllnearities under LFTMSK computer
program described below. FIG. 6 is an enlarged cross-section
taken through FIG. 5 to show the right mask 94 void in
masked photocathode electrode 91, the void extending to
3o ~ glass face 96 o~ image dissector tube 90.
-20-
~LZ59~5
.
!
During all bar gaging system operations a single-
axis bidirection s~eep signal is applied to the Y-axis
deflection coil and a fixed amount of current applied to
the focus coil, both as descri~ed below. Under normal bar
gaging operations~ there is no current applied to the X-axis
deflection coil. This causes the Y-axis scan to traverse
,the t'C" scan, or central image translating area of photo-
cathode electrode 91 as shown in FIG. 5. Whenever detector
l55 determines there is no bar 10 in the camera field-of-vlew,
; 10 l, computer 27 may select either right or left calibration mask
94, 95 by applying a positive or negative bias current which
is applied to the X-axis deflection coil. This X axis bias
shifts the Y-axis scan of photocathode electrode 91 to
corresponding "R" scan and "L" scan positions on opposite
I sides of "C" scan as shown in FIG. 5.
The X-axis bias has the effect of shifting the
, right calibration mask 94, or the left calibration mask 95,
i over electron aperture 92 in the image dissector tube 90.
, When the single Y~axis scan voltage is applied to the Y-axis
20 1I deflection coil, the image of right or left calibration mask
1 94, 95 is effectively moved up and down across electron
" aperture 92 in the same manner as actual bar shadow ~1 is
'I moved at the '!C" scan position.
lll It should be noted that the raw camera pulse on
25 ! wire 34 has the same pulse width when either the right or
left calibration mask 94, 95 is selected by computer 27 as
occurs when a bar shadow 81 having a corresponding size and
position is imaged on the central area of photocathode
-21-
:1
l~LZ59~
electrode gl. Hence, the masked photocathode electrode 91
affords an effective way of on-line checking of bar gaging
system drift as well as changes in optical and electronic
nonlinearities.
'
Camera Electronics
Typical camera electronics used in the FIG. 1
electro-optical bar gaging system is shown in FIG. 4 as
camera electronics 35. Details of camera electronics 35
may best be understood by referring to FIGS. 4 and 7 through
13. All electronic components therein are conventional
,
~ solid-state devices and include TTL (transistor-transistor-
.. ~
logic) logic elements where logic symbols indicate or imply
their use.
Generally, FIG. 4 shows bidirectional sweep
generator 97 which is shown in FIG. 7 and reference to FIG. 8
timlng diagram. Sweep generator 97 includes a 12 MHz.
crystal oscillator 124 that provides a train of basic square
wave clock pulses 8A for the entire electro-optical bar
gaging system. Except for actual measurement of processed
bar pulses, all digital operations are synchronized with
clock pulse 8A in addition to bidirectional sweep signal 8E
and sweep reset pulse 8D, the latter two pulses being generated
in sweep circuitry at approximately 300 Hz. Clock pulse 8A
and bidirectional sweep signal 8E are synchronized by sweep
reset pulse 8D every sweep cycle so that sweep signal 8E may
be divided for any purpose by using the appropriate sub-
multiple of clock pulse 8A. Clock pulse 8A is used for
actual measurements, while pulses for other bar gaging
-22-
system requirements are deri~ed by dividing clock pulse 8A
down all the way to the frequency of bidirectional sweep
signal 8E. It should be noted that the absolute frequency
value of clock pulse 8A and bidirectional sweep signal 8E
is not critical because the bar gaging system is calibrated
by actually placing standard size bars in each camera's
field-of-view. However, sweep stability and sweep linearity
are highly critical, since they directly affect the bar
gaging system accuracy.
Master clock 98 shown in FIG. 4 receives a train
of the 12 MHz, clock pulse 8A and the 300 Hz. sweep reset
~; pulses 8D from bidirectional sweep generator 97. Master
clock 98 includes buffers~ digital counter, divider and
logic circuits to supply all synchronized pulses used
throughout camera electronics 35 for timing and measuring
purposes. These include buffered 12 MHz. cl~ck pulses 8A,
buffered 300 Hz. sweep reset pulses 8D. Addltional pulses
generated within are a 300 Hzo fast strobe pulse 8H of
short duration and a data ready pulse simllar to pulse 8H
but longer in durationO The data ready pulse is outputed
on wire 99 and the other pulses carry their same identity
to other circuits shown in FIG. 4.
Window generator 100 receives the 12 MHz. clock
pulse 8A from master clock 98 and, by means of gates and
logic circuitry, generates window pulse 8F once every half
of each bidirectional sweep cycle as shown in timing diagram
FIG. 8. An inverted window pulse ~ is also generated.
Both window pulses ~F, ~ are fed to other circuits described
below. The width and timing of window pulses 8F, ~ are
~23-
9~5
determined by a control pulse on wire 101 fed ~rom computer
27. Briefly, the width of window pulses 8F, ~ is related
to the time required for sweep signal 8E to sweep only the
photocathode electrode 91, this being only a major portion
of each up or down half of an entire 300 Hz. sweep cycle.
For example, if the camera field-of~view is 7.62 mm. (three
inches) and the lens is 10.16 cm. (four inches), as they are
herein, then the 7.~2 cm. (three inch) field-of-view is
imaged down centrally to cover the entire face of phokocathode
electrode 91. Over-scanning of photocathode electrode 91
results in each up and down half of bidirectional sweep cycle
8E. This over-scanning is equally divided into two time
intervals at the beginning and ending of each up and down
half of bidirectional sweep cycle 8E. Thus, ~he sum of the
durations of window pulse 8F (abo~t 75%) and the overscan
(about 25%) equal the duration of each up and down half of
bidirectional sweep cycle 8E. As an alternative arrangement,
window pulse width may be established manually by selective
gating means not shown to replace the computer 27 conkrol
signal on wire 101.
During computer 27 programs RTMASK, LFTMSK, GAGRCL,
and CALIBR described below, window generator 100 is programmed
by way of wire 101 to modify the normal slze and timing of
window pulses 8F, ~. During RTMASK and GAGRCL, window
pulse size and timing are set for the size and location of
right calibration mask 94 in FIG. 5. During LFTMSK, five
window pulses sized and timed for each size and location of
le~t calibration mask 95 elements are generated one at a time
to selectively coYer khe entire left calibration mask 95.
-24-
~S9~5
During CALIBR, window pulse size and timing are selectively
set for size and location of right calibration mask 94 and
each of the five left calibration masks 95. The size of
the normal window pulses 8F, ~ is set by subroutine ~AGEIN
described below.
Still referring to FIG. 4, bidirectional sweep
signal 8E is fed from bidirectional sweep generator 97 to
Y-coil deflection drlver 102 and into the vertical or
Y-deflection coil in coil assembly 93. Constant current
from focus coil current source 103 is fed to the focus coil
in coil assembly 93. The magnitude of focus current is
adjusted to focus all elec~rons emitted from each point on
the photocathode surface 91 to a corresponding single point
in the plane of the electron aperture 92.
X-coil driver 104 is connected to the horizontal
or X-deflection coil in coil assembly 93. Under normal bar
gaging operations there is no effectivecurrent applied to
X-deflection coil. Therefore, the vertical single-scan of
the Y-axis may occur as the "C" scan centrally in the image
translating area o~ photocathode electrode 91 as shown in
FIG. 5. During calibration checks by computer 27 under
programs RTMASK and LFTMSK described below, positive and
ne~ative bias is applied alternately by control wires ].05
and 106 from computer 27 to X-coil driver 104. Thls will
cause the vertical single scan of the Y-axl~ to shift to
either the "R" scan or "L," scan position corresponding to
the ri.ght mask 94 or the left mask 95, depending on which
bias control wire 105~ 106 is energized. As an alternative
arrangement, the posit~ve and negative bias currents may
-25-
~%5~5
be selected manually from a source not shown instead o~
computer 27 supplying them.
In summarizing the image dissector tube 90 scanning
ef~ected by coil assembly 93, only single-scan Y-axis~ or
vertical, bidirectlonal scanning is present at any time,
this occurring continuously as an up and down sweep with
no blanking. Under normal bar gaging operations there is
no X-axis sweep, there being only a positive or negakive
bias applied to check gage system calibration when not
measuring bar shadow 81.
~ s bar shadow 81 is scanned over the camera ~ield-
of-view, output current from image dissector tube 90 drops
sharply as bar shadow 81 is met, then rises again when the
bar shadow is past. This current change, together with
electrical noise from the mill environment, is converted to
voltage, amplified in a preamplifier not shown in FIG. 4 and
is the raw camera signal output from camera head 31 and
appears on wire 34. This is, the raw camera signal at this
point consists of a not-too-well defined bar pulse mixed
with noise.
Image dissector tube 90 in camera head 31, operates
in a self-balancing measuring ~oop 107 together with camera
pulse processor 108, photomultiplier (P.M.) AGC circuit 109
which produces a variable control voltage on wlre 110, and a
voltage-controlled high voltage source 111 for P.M. section
of tube 90. The drift section of tube 90 is also ~ed from a
separate but stable drift secti.on high voltage source 112.
Camera pulse processor 108 is shown in FIGS. 9 and
10 with FIG. 11 illustratlng the processor timing pulses.
-26-
z~9~
Included are a buffer, double differentiators, level detectors,
zer-o~crossing detectors and an autocorrelator to remove
noise from the raw camera signal and from differentiators.
Signals so treated are combined with inverted window pulse
~ in processor logic to ensure that only bar pulses of
proper amplitude and occurring at the correct time, will be
passed outward for measurement purposes. This also prevents
passage of bar pulses when the window is not open. Camera
pulse processor 108 produces a buf~ered camera signal llA and
precision square wave bar pulses llP, llP generated by an
internal fllp-flop. Bar pulse width varies proportional to
bar shadow 81 and therefore proportional to bar dimension
between bar edges 82 and 83.
P.M. AGC circuit 109, which is shown in FIG. 12
and described ~elow, receives buffered camera signal llA and
includes a comparator, a switched-integrator and an amplifier
for producing a switched variable control voltage on wire
110. This control voltage is fed to P.M. section high
voltage source 111 for the purpose of varying the gain of
image dissector tube 90. The comparator establishes a
reference gain level and an internal logic circuit generates
an AGC blanking pulse 8G by combining window pulse 8F with
inverted bar pulse llP. The AGC blanking pulse effectively
defines the time intervals when the camera signal should be
sampled.
Action of the self-balancin~ measuring loop 107
Will now be described. When there is no bar 10 in the
gaging system, only light from box 30 is imaged on photo-
cathode electrode 91. This causes the P.M. section in image
dissector tube 90 to generate a current to flow on wire 34
which is proportional to the intensity of light from box 30.
The gain of P.M. section in tube 90 is adjusted to a high
level initially by the effective level of AGC control voltage
produced by circuit 109. As light intensity deteriorates,
or the i~age dissector tube 90 ages, AGC circuit 109 auto
matically compensates for this by adjusting the level of
P.M. section high voltage from source 111 to vary the gain
of the P.M. section of tube 90 and thereby maintain a constant
amplitude of the camera signal.
When bar 10 is imposed in the path of light from
box 30, AGC circuit 109 also functions to maintain a constant
output amplitude from image dissector tube 90. Self-balancing
measuring loop 107 thereby permits operation of image
; 15 dissector tube 90 at a hlgh sensitivity level while main-
taining a reasonably high signal-to-noise ratio which is
desirable for effective raw camera pulse processing.
Still referring to FIG. 4, precision bar pulses
llP, clock pulses 8A, clock reset pulses 8D and fast strobe
pulses 8H are fed to display timing 113. Logic circuits
therein are arranged to count clock pulses 8A for the duration
of each of two bar pulses llP occurring during a bidirectional
sweep cycle, then dividing by two. Counting is synchronized
by clock reset pulse 8D which occurs at the bottom of each
bidirectional sweep signal 8E. Logic circuits are strobed
by fast strobe pulse 8G in preparation for a binary bar size
signal being outputed on wire 114 for display purposes. In
order to avoid display flicker, the binary bar size signals
-28-
s
are averaged over a predetermined number of bidirectional
sweeps, such as 4, 32, 512 sweeps, by means not shown.
~; Binary bar size signals are fed over wire 114 to
digital indicator 115. This device includes integrated
counter-decoder-display modules calibrated to display in
decimal digits the uncorrected size of bar 10 obtained
anywhere in the camera field-of-view. The term uncorrected
bar size is applied to bar dimensions at this part of the
bar gaging system because no correction for optical and/or
electronic nonlinearities~ bar temperature and bar composition
has been made.
Computer 27 does make corrections to the uncorrected
bar size signals and feeds a corrected binary bar size
signal over wire 116 to corrected bar size digital indicator
1~ 15 117. This digital indicator is structured the same as
digital indicator 115. Both bar size indicators 115, 117
; have visual displays adapted to be synchroniPed and updated
every 512 sweeps under control of clock reset pulses 8D and
fast strobe pulses 8H. It is to be noted that the difference
between readings on bar size indicators 115, 117 signifies
to a bar gage operator, and to a rolling mill operator, that
(a) the correction features of the bar gaging system are
working as requi.red, and ~b) that the rolling mill is rolling
aim size product.
Computer correction of bar pulses llP is based
upon accurately determlning not only bar size but also bar
centerline position in the camera field-o~-view with respect
to the optical axis of camera head 31. To do this, bar
pulses llP, clock pulses 8A, clock reset pulses 8D and fast
-29-
: :;
llZ591~
strobe pulses 8H are bed to bar size and position accumulator
118 which is illustrated in block diagram FIG. 13 and the
timing of pulses is shown in FIG. 8. ~wo separate counter
; and latch circuits, each under control of a common control
gate, provide binary bar size output signals on wire 119 and
binary bar centerline posit~on output signals on wire 120.
The binary bar size signals on wire 119 are developed
similarly to the uncorrected bar size signals assoclated
~ with display timing circuits 113 described above. The
binary bar position signals permit corrections to be made of
the bar size signals to an accuracy of 1 part in 256 of the
camera field-of-viewO
Transfer of all data between the computer 27 and
other parts of the bar gaging system is carried out by gage-
computer data transfer logic circuit 121. Logic circuit 121
receives a command signal over wire 122 which is indicative
of computer 27 being of such state as to permit data transfer.
Command signal 122 is logically combined with the "data
ready" pulse on wire 99, which is generated by master clock
98 as described above. Their combined presence causes logiccircuit 121 to generate a "request to send" signal on wire
123 and synchronize the timing of the gaging sytem with
computer 27.
Bidirectional Sweep Generator
__.
Reference will now be made to bidirectional sweep
generator 97 shown in FIG. 7 block dlagram and FIG. 8
timing diagram. In order to ma~e bar size measurements to
a system accuracy of quarter commerclal tolerance in a 7.62
cm. (three inch) field-of-view, the bldirectional sweep of
-30-
1, !
9~ l
the Y-axis in image dissector tube 90 must be extremely
linear and repeatable. Conventional analog sweep circuits
are generally difficult to design and maintain to the level
of linearity required herein. But if a sacrifice in system
accuracy is acceptable for some gaglng sytems, then analog
sweep circuits may be considered. However, to meet the high
accuracy requirements of the present gaging system, the
bidirectional sweep of the Y-axis is generated by digital
' means with a crystal oscillator for a time base, digital
counters, and a fourteen-bit digital-to-analog converter
! that develops the actual bidirectional sweep waveform 8E.
Digital provisions are made to modify sweep waveform 8E as
- described below.
The time base provided is a highly stable 12 MHz.
crystal clock oscillator 124 having a square wave output.
Buffer 125 prevents nonuniform loading of time base 124
during sweep operations and feeds a train of clock pulses 8A
!I to dlfferential line driver 126. Output from driver 126 is
; ~ed as clock pulse 8A to master clock 98 in camera electronics
35. Buffer 125 output also feeds clock pulses 8A to digital
divider 127 which has counting and logic devices that generate
waveforms 8B and 8C. Waveform 8B is a input to up-down
counter 128, a 14-bit binary reversing counter. Waveform 8B
: ! is 5/12 of the basic clock frequency, or 5 MHz. Waveform 8C
is a timing pulse fed to counter reversing logic circuit 129
; and occurs twice in a 12 clock cycle per.iod. Waveform 8B
use~ 5 pulse locations in a period of 12 clock cycles and
waveform 8C uses two locations. This leaves five unused
Il .
,1
~ -31-
., ,
~;Z S915
,
pulse locations of the 12 clock cycles in the bidirectional
sweep period.
When the counter reversing logic circuit 129
I senses that up-down counter 128 has reached a full count
of all l's, it gates a count down enable signal back to
counter 128. The timing of the count down enable occurs at
the first timing pulse 8C after the full count is reached.
When counter 128 senses the count down enable signal, it
begins down counting on the next clock pulse 8B. When the
counter reversing logic circuit 129 senses all O's in counter
128, it generates a count-up enable signal on the next
occurrence of timing pulse 8C. Counter 128 will begin
counting up on the next clock pulse 8B.
Up-down counter 128 has a 14-bit binary output
which is fed over wire 13~ to 14-bit binary digital-to-
analog converter 131. Digital-to-analog (D/A) converter 131
tracks counter 128 and produces an extremely linear analog
birdirectional sweep signal 8E. This signal is buffered in
sweep circuit buffer 132, to prevent overloading of D/A
converter 131, and then fed as sweep signal 8E to Y-coil
driver 102 in camera electronics 35.
When up-down counter 128 reaches the last down
bit, it generates reset pulse 8D which resets logic circuit
129 and D/A converter 131. Differential line driver 133
feeds the reset signal to master clock 98 in camera electronics
35.
As mentioned above, there are five unused pulse
locations in a period of 12 clock cycles. These may be used
to provide an accurate nonlinear modification to the extremely
-32-
~Z5
.
linear sweep signal 8E by incorporating digital multipller
134 in series between digital divider 127 and up-down counter
128 as shown by dotted lines in Fig. 7. Digital multiplier
134 will receive waveform 8B instead of up-down counter 128
and by means of a suitable multiplier generate modified
waveform 8B'. Up-down counter 128 will receive modified
waveform 8B' and, together with the timing pulse 8C influence
` on the command signal, will alter the total up-count or
total down-count depending on the specific value of the
multiplier. This modification will still produce a triangle
sweep with slightly curved sides as indicated by modified
sweep signal 8E'.
The multiplier for digital multiplier 134 is fed
over wire 135 and may originate at computer 27. Alternatively,
the digital multiplier may be set by manual means not shown.
Regardless of its source the multiplier may be used to make
sweep corrections for overcoming optical and/or electronic
errors for which no other correction provisions have been
made herein.
Camera Pulse Processor
The camera pulse processor 108 is shown in FIGS.
9, 10 block diagrams, and FIG. 11 timing diagram. Camera
pulse processor 108 converts the raw camera pu]se on lead 3LI
into a precise bar output pulse on lead llP that has a width
with well-defined edges that accurately represents the
dimensional relationship between bar edges 82 and ~3.
Because of the differentiator, autocorrelator and other
design features described below, camera pulse processor 108
~33-
~Z59~
is very well suited to process the raw camera pulses at the
camera scanning rate of up to about 300 Hz., yet eliminate
the effects of camera signal and di~ferentiator noises.
Turning now to FIG. 9, camera pulse processor 108
is shown in block diagram form where alphabetical designations
refer to FIG. 11 waveforms. The raw camera signal from lead
34 is buffered and amplified by buffer 136 to produce signal
llA. The llA signal is differentiated by firs~ differentiator
137 which has an output llB. The first differential signal
llB is fed to low and high threshold detectors 138,~139
which have respective outputs llC and llD. Threshold
detectors 138, 139 produce output signals when their plus
; (+) input has a lower voltage than their minus (-) input.
The first differentiated signal llB is differ-
; 15 entiated again in second differentiator 140 to produce
output llE. The second differentiated signal llE is fed to
start and stop zero cross-over detectors 141, 142. These
detectors are set up to trigger on positive and negative
zero crossing transltions greater than 1 millivolt (mv.),
thereby producing bar pulse start zero and stop zero outputs
llF and llG, respectively. The bar pulse start zero and
stop zero outputs llF and llG, together with low and high
threshold signals llC and llD, are fed to fixed-delay
autocorrelator 143. Bar pulse start zero and stop æero
signals llF and llG are processed internall~ in respective
autocorrelator circuits as wlll be described below. Low and
high threshold signals llC and llD define narrow windows
during which the bar pulse start and stop signals llM and
11'~0" are tiggered, thereby establishing precise timing for
the leading and trailing edges of bar output pulse llP.
-3l~-
-` 1 1~25~1~i
As mentioned above, electronic camera 31 signal on
lead 34 may also contain electrical nolse. This may be high
frequency, low amplitude noise which is frequently coupled
magnetlcally into the electronic camera signal from high-
current, SCR(semiconductor rectifier)-fired, mill drive motor
controllers located near electronic camera 31. Without fixed-
delay autocorrelator 143, this noise will cause false
; triggering of bar output pulse llP. For example~ when a
transition of camera signal llA produces a first di~fer-
entiated voltage llB lower than a -3 volt threshold of
¦ detector 138, a low threshold signal llC w~uld be enabled
¦ which will allow zero crossing detector 141 to generate a
¦bar output pulse start trigger signal. Since the gain of
¦ differentiators 137 and 140 increases with input frequency,
a low-amplitude, high-frequency noise spike may produce a
first differentiator 137 output signal llB lower than the
-3 volt threshold of dete~tor 13~. This is precisely what
will happen in rolling mill environments without enhancement
o~ bar pulse generating circuitry.
For this reason, the ~ixed-delay autocorrelator
143 included in raw camera pulse processor 108 actual~y
includes separate autocorrelator bar pulse start and stop
circuits 144 and 145, respectively, as shown in FIG. 10. Bar
pulse start and stop circuits 144 and 145 are provided to
discriminate between second differentiated ~ignals llE
generated by high frequency noise from those generated by
valid bar pulse signals. During the falling edge of camera
signal llA, the second differentiated signal llE rises to a
positive voltage for about 10 microseconds before swinging
~L~2S9~5
to a negative voltage. For illustrative reasons, this
detail is not shown to scale in FI~. 11 signal llE waveform.
Zero crossing detection of the second di~ferentiated signal
llE by detectors 141 and 142 is the trigger point for the
start and stop bar pulses of signals llM and 11"0", thereby
establishing the leading and trailing edges of bar output
pulse llP.
Autocorrelator bar start and stop circuits 144 and
145 take advantage of the respective 10 mlcrosecond rise and
fall period of second differentaited signal llE. This is
done by generating autocorrelator enable start and stop
signals llL and llN as described below. Autocorrelator
start enable signal llL is generated when second differ-
entiated signal llE is continuously positive ~or at least
one-half o~ this 10 microsecond period before swinging
negative. Similarly, autocorrelator stop enable signal llN
is generated when second differentiated signal llE is
continuously negative for at least one-half of the 10 micro-
second period before swinging positive.
Autocorrelator start and stop enable signals llL
and llN are locially "anded" in circuits 144 and 145 with
respective low threshold signals llC and llD and bar pulse
start and stop zero crossing signals llF and llG to generate
bar pulse start and stop signals llM and 11"0". These
signals cause the precise generation o~ bar output pulse
llP. It will now be apparent that high frequency noise
which causes respective positive and negative excursions of
the second differentiated signal llE of less than 5 micro-
seconds duration will not generate autocorrelator enable
~.l.Z~9~5
start and stop signals llL and llN, thus preventing triggering
of bar output pulse llP.
Still referring to FIG. 10, operation of' auto-
Icorrelator bar pulse start circuit 144 will now be described.
¦Operation of autocorrelator bar pulse stop circuit 145 is
¦identical to circuit 144 with the exception that it responds
to a second aifferentiated signal llE which is continuously
negative for 10 microseconds before swinging positive. Both
¦circuits 144 and 145 employ conventional logic devices.
¦ Low threshold signal llC is inverted in amplifier
¦146 and fed to one of three inputs of NAND gate 147, the
¦latter providing the bar pulse start signal llM under proper
llogic conditions.
¦ Bar pulse start zero crossing signal llF is con-
~ditioned to Schmitt trigger 14~ and inverted in amplifier
~149, thereby producing trigger signal llH which is fed to
¦NAND gate 147 and one-shot delay device 150. A negative
I going transition of signal llH triggers one-shot delay
¦device 150 which produces a 5 microsecond logic "1" pulse
I llI at Q output, and a 5 mlcrosecond logic "0" pulse llJ at
¦Q output. Pulse llI is fed to one of two inputs to AND gate
151. Schmitt trigger 148 output ls also fed to the other
input of AND gate 151 as well as to the reset input of flip-
flop devlce 152. Pulse llJ ls fed to the clock input of
f'llp-flop device 153. The hig~l threshold signal llD is
wired to the data input of flip flop 152 to enable the
autocorrelator start circuit 144 during the falling edge of
camera signal llA and disable this circuit during the rising
edge of signal llA.
I ~Z59~
If signal llH is going negative, the input to
inverter 149 is going positive. This posltive going action
removes the reset condition on flip-flop 152 and puts a
logic "1" on one input of AND gate 151. Gate 151 will now
pass pulse llI to the clock input of flip-flop 152, thus
forcing a logic '~1" pulse llK at Q output. After a 5
microsecond delay, one-shot delay 150 will time out, thereby
causing output Q to change state and go to a logic "1" pulse
~ llJ. This action also clocks the input of flip-flop ~evice
153 which has its data input fed by signal llK from the Q
output flip-flop device 152.
If signal llK is a logic "1", flip-flop 153 output
Q will be set, thereby producing start enable signal llL.
Signal llL, which was generated from signal llH, is logically
combined with signals llH and llC, the inverted low threshold
slgnal, in NA~D gate 147 to produce the bar pulse start
signal 11~. Thus, it will now be readily recogni~able that
a bar pulse signal is delayed, then combined with itself to
perform a fixed-delay autocorrelation function.
If during the 5 microsecond period controlled by
one-shot delay device 150, the output of Schmitt trigger 148
goes low~ indicating that the second differentiated signal
llE is too narrow to be a valid bar signal, the reset of
f,ip-flop 152 goes low and ~orceæ signal llK to a logic "0".
When one-shot delay device 150 times out after 5 micro-
seconds, slgnal llJ will clock flip-flop 153 with its data
input in a low state. ~his will force the Q output of flip-
flop 153 to a logic "0" and prevents any further processing
of the bar signal.
-38-
I ~ 59~5
!1 One-shot delay device 150 is retriggerable so that
¦'lit may accommodate consecutive triggering pulses llH. If
multiple trigger pulses having a short duration of less than
, 5 microseconds trigger one-shot delay device 150, Q output
Isignal llI will stay high for all pulses and finally time-
out 5 microseconds after the last triggering pulse. AND
gate 151 allows flip-flop 152 to re-clock itself on each
pulse. Since the output of one-shot delay de~ice 150 stays
high continuously during these multiple triggering pulses,
the combining of signal llI with the Schmitt triggering
pulse in AND gate 151 guarantees that the clock line on
flip-flop 152 will undergo a logic transition from "O" to
; "1" for each triggerlng pulse.
As noted above, the bar pulse stop circuit 145 was
: !
identical with circuit 144, the exception being that stop
circuit 145 is triggered by a continuous negative golng
second differentlated signal llE before swing positive. For
tis reason, it will be apparent to those skilled in the art
that lnverter 154, NAND gate 155, Schmitt trigger 156,
i inverter 157, one-shot delay 158, AND gate 159, flip-flop
160, and flip-flop 161 devices have construction and
operating features the same as their counterpart in circuit
14ll. Therefore, it is felt an explanation of these devices
', i9 unnecessary to show how NAND gate 155 produces the bar
25 l pulse stop si~nal 11"0".
Having eliminated both the electrical noise in the
raw camera bar pulse signal and the noise produced by
differentiators 137 and 140, the bar pulse start and stop
,, .
' -39-
: ''I
!l ;
æ59~S
Il i
signals llM and 11"0" produced in respective circuits 144
and 145 now precisely define the timing of bar pulse leading
and trailing edges in relation to bar edges 82 and 83.
; Therefore~ signals llM and 11"0" are fed respectively to the
' set and reset inputs of flip-flop device 162. An inverted
window pulse ~ shown ln FIG. 8 and fed from window generator
lO0 is fed to the clock input of flip-flop device 162. The
data input of flip-flop 162 is tied to 0 volts. This will
enable device 162 to produce the bar output pulse only
during the presence of a window pulse 8F. The width and
timing of the window pulse is different for bar gaging
operations than in calibration checking operations as
explained above.
During bar gaging operations the Q output of
device 162 provides a precise bar output pulse llP whose
leading and trailing edges are free of noise and accurately
; define the lateral dimension of bar lO. During calibration
checking operations where computer 27 selects RTMASK or
LFTMSK programs, bar pulse llP w~ll accurately define right
and left mask 94 and 95 dimensions.
P.M. AGC Circuit
The AGC circuit 109 for the photomultiplier (P.M.)
section of' image dissector tube 90 is shown in FIG. 12.
P.M. AGC circuit lO9, which is an essential portion of self-
25 I balancing measuring loop 107, includes comparator 163,switched integrator 164 and driver amplifier 165. Ampllfier
165 drives P.M. section high voltage source lll with a
switched variable control voltage by way of wire llO. The
switched variable control voltage acts as an automatlc gain
-40-
, .
;
~.~æs9~5
control ~or tube 90. This is done by varying P.M. section
high voltage source 111 to maintaln anode current in tube 90
at a constant reference value.
Buffered camera signal llA is applied to one input
of comparator 163 through summing resistor 166 to summing
~unction 167. Summing ~unction 167 i.s limlted to positive-
going inputs by diode 168. A comparator reference voltage
from source 169 is adjusted at potentiometer sllder 170 for
the purpose of offsetting the bar pulse and establishing a
nominal value of the switched control signal that wlll
ultimately set high voltage source 111 at a nominal gain-
producing value.
The buffered and offset bar pulse at summlng
~unction 167 is to electronic switch 171 in switched
15 ~ integrator 164. The window pulse 8F and the inverted bar
¦ pulse llP are logically combined in AND gate 172 to produce
¦ AGC blanking pulse 8G shown in FIG. 8. When a window pulse
ls present and a bar pulse is absent, the AGC blanking pulse
8G causes electronic switch 171 to conduct current to
integrator amplifier 173 and to charge integrating capacitor
174. When both window pulse 8F and bar pulse llP are present,
electronic switch 171 opens and allows integrator output at
~unction 175 to maintain the nominal value input to driver
amplLfier 165.
Driver ampllfier 165 consists of summing re~istor
176 connected at one end to integrator output ~unction 175
and the other end to the input of operational amplifier 177.
Feedback resistor 178 controls the gain of driver amplifier
"
.
I ~5glS
165. Zener diode 179 limits the gain of driver amplifier
165 so as not to produce too high a switched control voltage
on wire 110 that would overdrive high voltage power supply
111. In summary, when an AGC blanking pulse 8G is absent
the buffered camera signal llA is conducted through AGC
circuit 109 and varies the P.M. section high voltage supply
111. During the presence of an AGC blanking pulse, llA
¦ is inhibited and the output of P.M. AGC circuit 109 maintained
¦ at a constant reference value determined by the charge on
¦capacitor 174 in integrator 164.
¦ Bar Size and Position Accumulator
¦ The size and position accumulator 118 is shown in
FIG. 13 with reference beind made to FIGS. 8 and 11 timing
¦ diagrams. In the present bar gaging system uncorrected
¦ digital bar size and bar position data fed to computer 27
¦ are developed similar to, but separately and independently
from, uncorrected digital bar size data displayed on
indicator 115. Accumulator 118 is provided with control
: ¦ gate 180 which assimilates bar pulse llP, clock pulse 8A,
¦ clock reset pulse 8D and fast strobe pulse 8H in bar size
accumulator circuit 181 and bar position accumulator circuit
¦ 182. Circuit 182 determines the bar centerline anywhere in
¦ the camera field-of-view. Both circuits 181, 182 are
¦ synchroni~ed by clock reset pulse 8D and both are strobed by
¦ fast strobe pulse 8H every complete sweep cycle.
¦ Control gate 180 detects the leading and trailing
¦ edges of each bar pulse llP and divides by two the number of
~ . '
~lZS9~5
clock pulses 8A occurring during the two bar pulses present
during the up and down halves of the sweep cycle. Control
gate 180 directs these clock pulses to the clock input of
14bit binary counter 183 in bar size circuit 181 where a
5 count of two bar pulses divided by two is registered. At
the end of a first sweep cycle this size pulse count in
counter 183 is transferred into the data input of 14-bit
binary latch 184, presuming a previous application of the
fast strobe pulse 8H has been applied to the latch's clock
10 input. At the beginning of the second cycle, counter 183 is
cleared by clock reset pulse 8D and is ready to receive a
new pulse count.
Fourteen-bit digital data, representing uncorrected
bar size between bar edges 82 and 83~ from the first sweep
15 cycleg is stored in latch 184 for a second sweep cycle.
During the second sweep cycle this data is transferred over
cable 119 to computer 27 for oorrection under computer
prograrn CMP~ST described below. At the end of the second
sweep cycle, counter 183 data is strobed into latch 184 by
20 pulse 8H, thus repeating the cycle. The counting of bar
size pulses is always one sweep cycle ahead of the latched
bar size data in bar size accumulator circuit 181.
~ ontrol gate 180 also detects the flrst llP bar
pulse edge at 185 during the up-half of a sweep cycle and
25 the first llP bar pulse edge at 186 during the down-half of
the same sweep cycle as shown in waveform 8G ln FIG. 8.
Control gate 180 determines the sweep time between pulse
-43-
llZ5915 I,
llP leading edges 185 and 186 and dlvides this time by two,
thereby establishing what will be referred to as the bar
centerline position sweep time. In addition, control gate
~ 180 also includes a bar position time base developed by
dividing the train of 12 MHz. clock pulses 8A by a factor of
160 in divider 187, thereby generating 8A/160 clock pulses.
8A/160 clock pulses are directed to the clock input of 8-bit
binary counter 188 in bar position accumulator 182 for the
i duration of the bar centerline position sweep time. The
10 ~ count registered in counter 188 represents centerline position
of bar 10 located anywhere in the camera field-of-view.
This bar centerline position was determlned totally inde-
pendently of the bar size measure~.ent made ln size accum-
ulato~ 181 or elsewhere.
At the end of a first sweep cycle the bar center-
line position count in counker 188 is transferred into the
data input of 8-bit binary latch 189, presuming a previous
application of fast strobe pulse 8H has been applied to the
latch's clock input. At the beginning of the second cycle,
counter 188 is cleared by clock pulse 8D and is ready to
receive a new bar centerline position pulse count.
Eight-blt data representing bar centerline position
in the camera fleld-of-view is stored in latch 189 for a
second sweep cycle. During the second sweep cycle this data
is transferred over cable 120 to computer 27 for use in
making optical error corrections to the bar siæe data in
accumulator 181 under computer program CMPNST described
below. At the end of the second sweep cycle, counter 188
-44-
;i9~;
data is strobed into latch 189 by pulse 8H, thus repeating
the cycle. Counting of bar centerline position pulses is
always one sweep cycle ahead of the latched data in bar
position accumulator 1~2.
Bar position accumulator 182 divldes one-half of a
sweep cycle into 256 increments at o.o46 mm. (0.016 inch)
per increment. The optical centerline of camera head 31 is
at the 128th increment. The incremental total represents
10.404 cm. (4.o96 inches) of Y-axis sweep applied to the Y-
axis deflection coil with a usuable field-of-view of approxi-
mately 7.62 cm. (three inches). The unusable field-of-view
is 2.784 cm. (1.096 inches), the distance the Y-axis deflection
coil sweeps off the top and bottom edges of photocathode
electrode 91.
Computer
A block diagram of the FIG. l electro-optical bar
gaging system computer 27 is illustrated in FIG. 14. Com-
puter 27 is a digital system programmed to perform the various
functions described below. A commercially available Fortran
programmable, or hardwired, minicomputer may be used, or if
desired, computer 27 may be shared in overall rolling mill
~; control computer installation. Computer 27 is exemplified
~ereln as a Westinghouse Electric Co., U.S.A., model W-2500
with an operatin~ system for accommodating various levels of
tasks as noted below.
Computer 27 is provided with conventional main
components including input buffer l90, output buffer l91,
disc storage 192, disc switches 193, core storage 194, all
communicatlng by various channels with data processlng unit
~zs9~s
195. Computer 27 operations are controlled sequentially
according to of~-line and on-line computer programs 196.
These comprise: computer maps 197 ~hown in FlGS. 15 and
'16, service programs 198, bar gage data program }99, com-
pensation programs 200, call~ration program 201, recalibration
pro~rams 202~ and histogram programs 204, all described below.
All communicatlons with the bar ~aglng system
computer 27 ~rom external sources are by way of input
buffer 190 which lncludes means for convertin~ input analog
and digital signals to digital ~orm. The~e include signals
fed by wires or cables into the computer as follows: camera
electronics 35 on cable 36, hot metal detector 57 on wire
58; bar temperature 50 on cables 53, 54; bar aim size 42 on
wire 43; bar composikion 44 on wlre 45; other data 46 on
cable 47; control system 67 on cable 68; CRT terminal 60 on
cable 61; and printing terminal 63 on cable 64.
All communlcations with bar gaglng system computer
27 to external sources are by way of output bu~fer 191 which
also includes means ~or convertlng output signals to digital
Z0 and analog form. These lnclude signals ~ed by wlre3 or
cables ~rom the computer as ~OllOWB: control system 67 on
cable 66, and camera electronlcs 35 on cable 37.
Individual wires in signal cables have been used
through the drawing~ and these have been cabled according to
thelr source and ~unctlon as described above.
CRT terminal 60 include~ a keyboard for operator
interaction wlth computer 27.
_~6-
Printing terminal 63 includes a keyboard for
operator interaction with compuker 27. Terminal 63 computer
printout 65 includes a plot of bar diameter deviation, as
well as tabular data listed below.
Generally, it is permissible for both terminals 60
and 63 to plot the same data. All interactions from either
keyboard are by way of program mnemonics listed, for example,
as follows:
GAGE OFFLINE SYSTEM !
MNEMONICS ARE AS FOLLOWS:
HS - HISTOGRAM FOR EACH HEAD
MP - BUILDS FIELD OF VIEW COMPENSATION MAPS
CL - PERFORMS A CALIBRATION CHECK ON LEFT AND RIGHT MASKS
TY - PRINTS MAPS, SLOPE & OFFSET FACTORS, AND MASK VALUES
; 15 OF - ALLOWS ENTRY OF SLOPE AND OFFSET CORRECTION FACTORS
ZE - ZEROES ALL MAPS AND CORRECTION FACTORS !IICAUTIONII!
LF - LEFT MASK DRIFT TEST
RT - RIGHT MASK DRIFT TEST (ALSO ALLOWS ENTRY OF WINDOW)
TR - DISK TRANSFER OF GAGE COMMON TO CONTROL SYS. AREA
XT - EXITS TO MONITOR AND ATTEMPTS TO WRITE COMMON AREA
CONTAINING MAPS, SLOPE AND OFFSET CORRECTION FACTORS~
MASK VALUES, AND WINDOW VALUES TO THE DISK. THE DISK
FILE WILL ONLY BE UPDATED IF DISK SWITCH 12 IS UP.
THIS FILE IS READ FROM THE DISK WHEN THIS TASK (20)
IS CALLED BY THE MONITOR.
Disc switches 193 include switches designated
"switch 10" and "switch 12" in the programs below. These
switches must be turned ko "Write Enable" ko update programs
or data on the disc.
Computer P~
The following table lists individual and groups of
programs as~ooiated with computer programs 196 used herein.
-47-
l ~zs9~s
COMPUTER PROGRAM
IDENTIFICATION USED
OFF-LINE ON-LINE
I MAPS (197)
DISC MAP X
CORE MAP X X
i SERVICE PROGRAMS (198)
IDL HANDLER
M:IDL X X
CD:ID~ X X
EB:IDL X
GAGTSK X
SUBCLL X
GAGTRN X
BAR GAGE DATA PROGRAM (199)
GAGEIN X X
COMPENSATION PROGRAMS (200) X
CORDAT X
ZERO
MAPRNT X
GAGTPC X X
CMPNST X X
~ CA~IBRATION PROGRAM (201)
1 25 CALIBR X
RECALIBRATION PROGRAMS (202)
RTMASK X
GAGRCL X
LFTMSK X
:; 30 HISTOGRAM PROGRAM (204)
X
.: .
HISTOGRAM INTERFACE
; WITH CONTROL SYSTEM X
MAPS (197)
DISC MAP, See FIG. 15: Program address in disc
: skorage 192.
CORE MAP, see FIG. 16: Program address in
hexadeclmal core storage 194.
SERVICE PROGRAMS (198)
IDL Handler, M:IDL routlne handles all data trans-
fers between the IDL hardware (channels 30 and 32) and the gage
data input subroutine GAGEIN. It communicates to the IDL
~48-
~5915
. I .
hardware via the IDL channel driver CD:IDL. A double
Ibuffering scheme is used to speed up the total transfer time
; by initiating an additional IDL transfer on both channels to
a second data buffer ~ust before exiting from the handler.
In this way data can be transferred into this second buffer
by the IDL hardware using service request interrupts (SRI's)
executed in the out-of-sequence range while the gage software
is busy processing data from the first buffer. When this
processing is completed~ the handler is re-entered. If the
data transfer on the second buffer is not complete, the task
is suspended until the IDL external MACR0 routine detects
two buffer overflow interrupts. The task is unsuspended by
the IDL external MACR0 routine EB:IDL when 2 buffer overflows
have been counted. If the data transfer on the second
buffer is complete, or after the task is unsuspended by
EB:IDL, the buffers are effectively switched and a data
transfer using buffer 1 is initiated and an exit is made
from the handler. The gage software now processes the data
in buffer 2 and repeats the above sequence.
A watchdog timer with a .5 second timeout is set
before initiating each IDL transfer. If two buffer over-
flows are not returned within this time period, the clock
routi.ne will unsuspend the task and sets the variable
IST~T=l to indicate an IDL transfer timeout error.
The variable IBUF is set by this routine to
indicate which buf~er, 1 or 2~ contains data from the last
IDL transfer. The variable IRSTRT must initially be set to
-49-
" ~L2~i9~S
"
0 by the calling task SQ that this routine knows when entry
;has been made for the first time. When IRSTRT=0, the double
buffering mechanism is initialized. This routine then sets
IRSTRT-l to indicate that the double buffering operation is
in progress. If entry to the handler is made with IRSTRT=-l~
an abort IDL comment is sent to both IDL channe~ls to stop
any transfer in progress. This command is usually intiated
by the calling task before doing a call exit so that all IDL
transfers are stopped.
This routine calls the IDL channel drlver CD:IDL
~ and utilizes the IDL external MACR0 routine EB:IDL. There-
-~ fore, these routines must be linked with the IDL handler
M:IDL.
IDL handler, CD:IDL routine is used to transfer
data from the handler control blocks (HCB) defined ln the
IDL handler M:IDL to the IDL hardware (channels 30 and 32).
Control is transferred to this routine by loading the
address of the HCB into the B register and jumping to CD:IDL
(CD:IDL must be declared external). The HCB is a 9 word
table having the following format~
-50-
~2S9~i
.
Word Example Using
No. Explanation Channel 30
0 Forced Buffer Input IDL Code DAT X'B30'
1 Abort IDL Code DAT X'F30'
2 Return Address - 1 ADL RTRl-l
3 Blank DAT 0
4 Buffer Input IDL Code DAT X'530'
5 Core Location Containing
Addr. to data DAT X'llFB'
6 Number of Words to be
Transferred DAT 20
; 7 Address of Data Buffer SIZ.E 1
8 SRI Address Vector
(100~SRI x 2) DAT 354
This routine performs three functions using the
HCB table. First, an abort code (HCB - word 1) is sent out
on the I/O (input/output) subsystem. The lower seven bits
of this word define the channel number to be aborted.
Second, a forced buffer input (HCB - word O) is sent out on
the I/O subsystem. Thi.s command ini~ializes the IDL hard-
ware on the selected channel. Third, the buffered input
transfer code is sent out on the I/O subsystem to initiate
the data transfer. The data is transferred into core memory
from the selected IDL channel via service request interrupts
(SRI). ~he pointers and counters used by the SRI's are ~et
up by thls routine using data supplied in the HCB' 9 .
IDL Handler, EB:IDL routine ls called by the
POS/l buffer overflow servlce request interrupt routlne
in the out-of-sequence lnstruction range ln response to
buffer overflow lnterrupts which occur when a buffered
-51-
. 1~2S9~5
input data transfer on any o~ the IDL channels 30 and 32 are
completed. Each entry to this routine causes the buffer
overflow count word (ECB7) in the external MACRO control
block to be lncremented. When this count reaches 2, the
task which was suspended by the IDL handler M:IDL is
unsuspended. I~ this count is not 2, return is made to the
POS/l buffer overflow exlt routine M:BOX and the state of
the suspended task ls unchangedO Thus, when the IDL handler
M:IDL requests data from both four IDL channels it clears
the bu~fer overflow count and suspends the task. It will be
unsuspended when the IDL external MACRO routine counts two
completion buf~er over~low interrupts.
GAGTSK, a disc resident task (Task 20), is an o~f-
line task designed to read disc resident off-line gage
subroutine overlays into core, trans~erring control to them.
GAGTSK calls a particular subroutine into core in response
to mnemonic parameters passed to it by the operator inter-
active subroutine caller overlay SUBCLL described below.
All programs and their mnemonics are described in the
listing of the subroutine SUBCLL. GAGTSK also trans~er a
disc resident common area into core9 and, if disc sector
switch 12 is write enabled, writes the updated common area
back to the disc when exiting f'rom the task.
An o~f-line busy ~lag I~AGOF is set on entry to
this task, and is cleared upon exit.
SUBCLL, a disc resident ~ubroutine as an overlay,
is run in the o~f-line mode by means of which an operator
may interact with the gage off-llne system to run any of
the available off-line bar diameter gage programs. It is
-5~-
l~ZS9~S
transferred from disc to core and run by the off-line gage
task GAGTSK (Task 20) by means of a system monitor disc-
read-and-transfer-control routine. Operator entered
mnemonics determine subroutine disc sectors which are
returned as subroutine parameters to GAGTSK, which in turn
transfers and runs the desired subroutine overlay. Sub-
routine functions are described in th~s program listing, and
are available to the operator in response to his request for
assistance.
GAGTRN program runs in the gage off-line system.
It transfers a 572 word gage data block from one predetermined
;~ ~ disc area to another area designated for control system 67.
It performs a disc-core-disc transfer using the gage common
stora~e area for intermediate storage. Disc switch la must
be write enabled.
BAR GAGE DATA PROGRAM (199)
GAGEIN, an auxiliary subroutine, is always appended
to any subroutine requlring bar gage data. It calls the
ID~ handled (M:IDL, CD:IDL, EB:IDL), also appended, to
actually acquire the bar position and diameter data, and
the compensate subroutine (CMPSNT), also appended, if com-
pensation is required. It averages the good readings
returned, both bar position and diameter, calculates deviations,
and stores the result~ in common tables. Validity tests are
made and error flags set as needed.
COMPENSATION PROGRAMS (200)
GAGMAP, a disc resident subroutine as an overlay,
` is run in the off-line mode which generates a compensation
-53-
'
1 ~2S~L5
.
table u~ed by an on-line bar dlameter gage tasks and sub-
programs, and those off-line gage programs requiring
compensated size data. The tables reside in a common area
and are used to compensate for image-tube nonlln~arity
1 across lts field-of-view. The tables are formatted and
output to printer 63. This program is requlred to be run
before any bar-diameter data can be considered valid. It
'~ is invoked by the subroutine SUBCLL, and requi~es operator
interactlon.
The compensation map consists o~ 256 entrles
corresponding to the 256 possible bar positlon~. Element
one represents the bottom of the total 10.404 cm. (4.0g6")
field and element 256 represents the top of the field.
Each element contalns correction data to be 3ubtracted
from the measured bar size based on the positions of the
top and bottom edges o~ the bar. The actual correction
is performed by subroutine CMPNS~. Using the edge 82, 83
positions rather than the center positlon allows the map
to be used for all size~ of bar 10.
During the map buildin~ procedure, a 12.7 mm.
(1/2t') machlned sample bar 10 ls moved +47.1 mm. (1.5"j
back and forth in a plane perpendicular to the optical
axls. While bar 10 1~ belng moved, ~A~MAP ls executed in
the o~-llne caLibr~tion ~ystem. ~hi~ program proae~e~
10,000 mea~urements and calaulate~ the average deviation
at each increment o~ bar posltion. These intermediate
results are stored in a 256 element table called ISUM.
The final oompensation map based on bar edge 82,
83 positions is generated from th0 ISUM table bg the
followin~ steps:
-54-
~LZ~
i,
;: :
1. The compensation map is cleared.
2. A computer simulation is performed in which
; an imaginary 12.7 mm. (1/2") bar 10 is positioned at o.406
mm. (0.016") above the center of the field-of-vlew (slot
129). The positions at the top and bottom bar edges 82, 83
are calculated metrically as follows:
d 83 [field-of-view center p_~4~61nn +o.406 + bar size/ ]
(Eq.l)
Edgme 82= [field-of-view center posit~on +o.406 - (bar size/2]
(Eq.2)
Example:
Top Edge 83= (52.018 + o.406 + 12.7~2) ~ o.406 = 144 (Eq.3)
Bottom Edge 82= (52.018 + o.406 - 12.7/2) . o.406 = 113 (Eq.4)
3. The value stored in the map at the upper
edge 83 position (144) is the sum of the deviation stored ln
ISUM table corresponding to the position of the center of
bar 10 (129) and the value stored in the map at the lower
edge 82 position (113).
IMAP (upper edge
83 position) = ISUM (center bar position) ~ IMAP
(lower edge position) (Eq.5)
IMAP (144) = ISUM (129) ~ IMAP (113) (Eq.6)
4. Steps 2 and 3 are repeated by incrementing the
center position of the bar 10 to 0.812 mm. (0.032") above
the center of the field-of-view, then 1.218 ~m. (o.o48~
1.624 mm. (o.o64"), etc. This is repeated until the upper
edge 83 of bar 10 goes beyond +47.1 mm. (~1.5") above the
center of the field-of-view.
-55-
:,
llZ5915
'IIMAP (145) - ISUM (130) + IMAP (114)
IMAP (146) = ISUM (131) + IMAP (115)
IMAP (147) = ISUM (132) + IMAP (116)
IMAP (220) = ISUM (205) + IMAP (189)
IMAP (221) = ISUM (206) + IMAP (190)
The upper half of the map is now complete.
5. ~he lower half o~ the map ls filled in the
same manner. Based on the same 12.7 mm. (1/2") sample bar
10 located at the center of the field-of-view (128) the
positions of the upper and lower edges 83, 82 are calculated
metrically:
Top Edge 83 = (field-of-view center + bar2size) ~ o.406 (Eq.7)
Edge 82 = (field-of-view center _ bar2Size) ~ o.406 (Eq.8)
Top Edge 83 = (52.018 + 12.7~2)/0.406 = 143 (Eq.9)
Bottom Edge 82 = (52.018 - 12.7/2)/0.406 = 112 (Eq.10)
6. The map value for lower edge 82 of the bar
(112) is the sum of the devlation stored in ISUM corresponding
to the position of the center of the bar (128) and the map
value stored at upper edge 83 of bar 10 (143).
IMAP (lower edge 82 position = ISUM (center bar position) + IMAP
(upper edge 83 position)
(Eq.ll)
IMAP (112) = ISUM (128) ~ IMAP (143) (Eq.12)
7. Steps 5 and 6 are repeated by successively
decrementlng bar 10 position by 0.406 mm (O.016") from the
center of the field-of-view until the lower edge 82 of bar
10 goes beyond -47.1 mm (1.5") from the cenker of the
fleld-of-view.
-56-
l~S~lS
IMAP (111) = ISUM (127) + IMAP (142)
IMAP (110) - ISUM (126) ~ IMAP (141)
IMAP (109) = ISUM (125) ~ IMAP (140)
IMAP ( 36) = ISUM ( 52) ~ IMAP ( 67)
IMAP ( 35) = ISUM ( 53) + IMAP ( 68)
The lower half of the map is now complete.
8. Map positions above 221 and belo~ 35 are not
used. These positions correspond to the unused portion of
~; the field-of-view in the shadow of the photocathode tube
illustrated in FIGURE 5.
9. Map elements lll to 143 are zero. This corres-
- ;
15 ~ ponds to an area -6.35~mm~ (0.25") from the center of the
: ~ field-of-view. -
10. The map corresponding to camera head 31 is- stored~ in a common~data~area storage labeled FCOMPl.
CORDAT is a program~run under the gage off-line
~20 system. Its purpose is to allow the operator to enter the
slope and offset correctlon factors for camera head 31. The
two variables are:
IMULTl - Slope correction factor for camera head 31.
IOFSTl - Offset correction factor for camera head 31.
Slope correction is added to all bars by the field-of-view
compensation subroutine CMPNST based on the following
formula:
Size = (12.7 mm.-Size)~IMULTl
Offset correcti.on i.s added to all bar sizes by the fleld-of-
view compensation subroutine CMPNST based on the following
'ormula:
S9~;
Size = Size - IOFSTl
ZERO is a program run in the off-line gage system.
Its purpose is to zero the compensation map, all slope and
offset correction factors, and the right mask calibration
constant.
MAPRNT is another program run under t~e off-line
gage system. It does not require operator intervention.
Its purpose is to print the field-of-view compensation map,
slope and offset correction factors, and left and right mask
values.
GAGTPC program calculates hot aim size based on
an internally stored compensation equation. Three variables
are required for this~equation. First, the % carbon is
,
obtained from IGRADE in common area BDCCOM. Second, the
bar temperature is obtained from ITMP22 in common area
; ~ SYSCOM. Thlrd, the cold aim size is obtained from ICDAIM
in common area BDCCOM. The calculates hot alm size is
stored in a predetermined area in common storage BDCCOM.
CMPNST, an auxiliary subroutine, is appended to
any subroutine requiring gage diameter data compensation.
Specifically, this subroutine limearizes the bar measure-
ment data f'or its position ln the gage field-of-view,
coxrects the measurement daka for slope and offset data per
subroutine CORDAT and performs automatic callbration from
right mask data generated by subroutine GAGRCC.
Bar 10 size data from camera head 31 is linearized
by the CMPNST subroutine using compensation map FCOMP1
generated by off-line program GAGMAP. Compensation is
performed by the following steps.
-58-
.
~ 5g~L5
1. The bar size and position data from accumulator
118 are used to determine the positions of the upper and
lower edges 83, 82 of the bar 10 in the compensation map
metrically as follows:
-5;~ pper ed~e 83 posi~ion~- (ce~ter bar position -~ bar ,size/2)/0.406
-Lower edgè 82 pbsit~ion~ teenber bar pas~tion - bar size/2)/0.406
If the center of' a 25.4 mm.~(1") bar~is~positioned 1~3.05~
mm. (3/4") above the center of the fleld-of-view, the position
of the bar center is 52.018 mm. (2.048")~ + 19.05 mm. (0.75")
' 10 = 71~.07 mm. (2.798"~ The upper and~lower bar edge,positions
are~determlne~;as previously~descr1bed.~That is~
` upper Edge 83~ 2 L'
Positio~n = ~71.07 +~ 52~ 0.406 = 203 (E~.13)
ower~dge &2 ~ 2
' Positlon =~71.07 -' 5'4) ~ o.406 = I40 (Eq.14)
2.,, The compensati~on values corresponding to the
upper and lower bar edges 83, 82 are obtained from the map
and assigned values ICORl and ICOR2 respectively.
ICORl - IMAP (Upper Edge 83 Position) (Eq.15)
ICOR2 = IMAP (lower Edge 82 Position) (Eq.16)
3. If both upper and lower edges 83, 82 are above
the center of the field-of-view, then:
; Corrected Bar Slze = Uncorrected Size - ICORl ~ ICOR2
(Eq-17)
4. If both upper and lower edges 83, 82 are below
the center of the field-of-view, then:
Corrected Bar Size = Uncorrected Size + ICORl ~ ICOR2
(Eq.18)
-59-
~1~5~S
5. If upper edge 83 is above the center of the
field-of-view and lower edge 82, below, then:
Corrccted Bar Size = Uncorrected Size ICORl - ICOR 2
(Eq.l9)
CALIBRATION PROGRAM (201)
CALIBR is a program run in the off-line gage system.,
It does not require operator intervention. Its purpose is
to establish a performance log for the gage on printer 63.
It performs the following functions:
1. Deflect to each left and right mask 95, 94 and:
a. Measure and print size of each mask;
b. Calcu~ate and print deviation from stored
mask value;
c. Measure and print (+) slope value;
d. Measure and print (-) slope value;
e. Print window value used for each mask.
,~ ~ 2. Measure and print analog test size, ~ and -
slope values.
3. Measure and print digital test.
4. Print calibration update values used by'
~ recalibration.
; RECALIBRATION PRO~RAMS (202)
RTMASK~ a disc resident subroutine is an overlay,
i6 run in the off-line mode by means of whlch any Or the
followlng bar diameter gage functions may be exercised:
1. Right deflect electronic wlndow gates may
be changed to accomodate changes in image-dissector 90
parameters.
-60-
2. Right deflect diameter reference values,
stored in common tables, may be updated to compensate for
drift, component aging, etc.
3~ If no changes are desired, the program can be
run cyclicly, with a deviation printout on printer 63 to
observe electronic and temperature related drift.
Upon return from this subroutine, the image-
dissector 90 sweep is returned to the center, a full elec-
tronic window gate is restoredg and the current through the
back-llght source lamps is reversed to prolong lamp life.
This program is designed primarily as a long-term drift
check tool, with the additional capability of updating the
window gate and reference table value. It is invoked by
the subroutine SUBCLL, and requires operator interaction.
GAGRCL is a program run under the on-line system.
It requires no operator interaction. Its purpose is to
automatically recalibrate the bar diameter gage periodically
by updating the drift correction term ITMPl described above.
It deflects the camera sweep to scan the right mask 94 and
- 20 equate the drift term w1th any deviations from an initial
calibration reference value. Before exit, the sweep is
returned to the center with a normal window, and the back-
light-source is reversed.
The automatic recalibration system provides the
means to maintain gage accuracy by checking the calibration
whenever bar lO is not in the gage field-of-view. This
recalibration system is implemented after bar lO clears the
l~ZS915
!
gage, and before the next one passes through, as determined
by a signal from hot metal dectector electronics 57. This is
accomplished using software to calculate a scaling factor
based on the differences between an on-line measurement of
a known internal reference, such as right mask 94, and an
off-line measurement of the same internal reference made
during system calibration. Following a recalibration,
the measurements on the next bar 10 in the gage field-of-
view is corrected using this scaling factor.
The key to the recalibration measurement is masked
photocathode electrode 91 on the front of the image dissector
tube 90. The mask pattern is shown in F`IGURE 5. The photo
cathode electrode 91 has five 2.54 mm (0.1 inch) wide masks
spaced 2.54 mm. (0.1 inch) apart on the left side and a
single 6.35 mm. (0.25 inch) mask centered on the right side.
Construction and operating features of image dissector tube
90 and photocathode 91 are described above in FIGS. 4, 5~ 6.
There are "C" scan, "R" scan and "L" scan positions established
by X-axis bias. There i5 no distinction between right mask
camera signals and bar camera signals. If no ad~ustments
are made to the electronics, the measurement of the right
mask at time Tl should be the same as the measurement at
time T2. Any differences are assumed to be electronic
dri r t.
The recalibration system only uses right mask 94
to calculate the correction factors. The five left masks 95
are only used in the off-line calibration system for linearity
-62-
checks. The right mask for camera head 31 is measured and
saved on the disc by executing -the right mask program "RT"
in the off-line calibration system. The variable is stored
in core in common data area MSKCOM under the name IMASKl.
The data is transferred from disc to common area MSKCOM in
core when the control system is activated.
The on-line measurement of right mask 94 is
performed by the GA~CL task. After hot metal detector 55
detects the tail end of bar 10 being rolled clearing the
gage, GAGRCL deflects the dissector tube image to the right
and measures mask 94. The difference between the measured
value from camera 1 and IMASKl is sf,ored in variable ITMP1
in common data area TMPOFF. This value represents changes
in the gage measurement from the initial calibration to the
on-line calibration.
The on-line correction function is performed in
subroutine CMPNST using variable ITMPl. A slope correction
is applied to each measurement based on the ~ollowing metric
formula:
For Camera Head 31:
Bar Size X ITMP1
Corrected Bar size - Bar size - ( 12.7
(Eq.20)
As an example for an ITMPl = 0.01524 mm. (O. ooo6~
The corrected size [12 X 0 01524-
for a 12.7 bar = 12.7 - 7 12 j - ~ = 12.68l~7
(Eq.21)
for a 25 4 bar = 25.li _ [25 l-X12-70152l] = 25.3694
(Eq.22)
The corrected size [ 8 ~ 01 24
for a 38.10 bar - 38.10 _ 3 10 12 j 5 -] = 38.0451
(Eq.23)
--63--
~a259~l5
The amount of correction for a 12.7 mm (1/2l') bar
ls equal to the value ITMPl. Similarly, the correction is
2 X ITMPl for a 25.4 mm. (1.0 inch) bar and 3 X ITMPl for
a 38.10 mm ~1.5 inch) bar. This is because lens 86 reduction
is 1/2. Thus a 12.7 mm. (1/2") bar is projected as a 6.35
mm. (0.25 inch) shadow on photocathode electrode 91 which
is the approximate width of right mas~ 94.
LFTMSK, a~disc resident subroutine as an overlay,
is run in the off-line mode by means of which any of the
following bar diameter gage functions may be exercised.:
1. Left-deflect electronic windo~ gates, used
to seIect each of the five left-deflect bar references on
left mask 95, may be changed to accommodate changes in
i~age-dissector tube 90 parameters.
2. Left-deflect diameter reference values, stored
in a common table, may be updated to compensate for drift,
component aging, etc.
3. If no changes are desired, the program can be
run cyclicly, with a deviatlon printout on printer 63 of
each of the five left-deflect etched bar references, to
observe electronic and temperature related drift. Maximum
cycle time is 32,000 seconds.
Upon return from this subroutine, the image-
dissector tube 90 sweep is returned to the center, a full
electronic window gate i8 restored, and the current through
t~e back-light source lamps is reversed, to prolong lamp
life. This program is designed as a field-of-view and
electronic drift check tool~ with the additional capability
-64-
~259~
of updating the window gates and the reference table valuev
It is invoked by the subroutine SUBCLI,, and requires operator
interaction.
HISTOGRAM PROGRAM (204)
GAGHST is a program run under the off-line gage
system. It re~uires operator intervention. Its purpose is
to gather a number of readings from camera head 31, store
in core 194 table IBDGI2, and print a histogram table for
camera head 31 binned at 0.0051 mm (0.0002 inch) increments
for a range of +0.127 to -0.127 mm. (+.005 to -.005 inches)
shown typically in FIG. 17. In addition, it calculates and
prints -the mean and standard deviation of all readings.
The operator must enter the number of readings desired,
the bar aim size, and request the use of the histogram table
~ith control system 67 as shown partially in FIG. 19.
TWO-DIMENSION AND PROFILE GAGING SYSTEM
Referring now to the drawings, particularly FIG.
lA, there is shown a computerized electro-optical system for
gaging two bar dimensions and profile having dual back-
lighted cameras mounted on a scanner in a hot steel bar
rolling mill. rrhis embodiment of the invention is similar
to that shown in FIG. 1, but lncludes the further improve-
ment of using two gaging camera systems and a scanner as
shown in FIG. lA. Camera ~2 electronics 39 is the same as
that for camera #1 electronics 35 shown in FIGS. 4 to 13,
except that all refernce numerals for devices, circuits,
waveforms, timing diagrams, computer programs, and the
- -65-
.~ :
' .
i!
like have a prime (') identification for designating second
camera electronics. The gaging system measures two orthog-
onal diameters and profile o~ bar 10, ~or example, beyond
the exit side of roll stand 11 while the scanner is either
stationary or scans the peripheral surface of bar 10 a
prescribed angular displacement. As explained below, the
two diameter signals and a scanner position signal are fed
to a computer which plots the lateral profile o~ bar 10.
Ultimately, the bar profile data is displayed, recorded and
transmitked to a rolling mill control system which uses
this data to control size and shape of bar 10 by (a) settlng
the lateral gap of the rolls in stand 11, (b) setting the
vertical alignment of the rolls in stand 11 and (c) setting
the lateral gap of the rolls in the stand immediatel~J
preceding stand 11.
More specifically, dual head scanner 12 consists
of reversible scanner mechanism 13 driven by motor 14 which
is energized over wire 15 by variable speed controller 16.
Two-mode selector switch 17 provides for either manual or
automatic scanner operation as signalled over wire 18 to
controller 16. This depends on whether a g~ging sytem
operator or the computer is to exercise optional manual or
automatic scanner 12 control. Under manual control mode,
manual speed, start-stop and scanner 12 direction control
originates in control device :L9 and these signals are ~ed
over wire 20 to controller 16. Under automatic control mode,
the manual control signal sources are disabled and scanner
controller 16 receives corresponding signals from the
computer as will be explained below.
l:~Z5~
Scanner position encoder 21 is coupled to mechanism
13 and generates an analog signal representing the absolute
posit~on of scanner 12 rotation. The encoder signal ls fed
over wire 22 to scanner position electronics 23 where it is
converted to both analog and digital scanner position signals.
The analog scanner position signals are fed over wire 24 tG
scanner posit:Lon indicator 25 which may be observed by the
gage operator when the scanning operation is under manual
cont:rol. The digital scanner position signals are fed over
wire 26 to computer 27l~ where they are assimilated with
computer command signals u~der automatic control mode of
,~.
scanner 12. Computer 27i then generates stark-stop signals
and speed control signals as described below. These signals
are fed over respectlve wires 28 and 29 to scanner controller
: `
16. During the automatic control mode, the digital scanner
position signals are used in bar profile determining
operations, also described below.
Mechanism 13 o~ dual head scanner 12 is adapted to
rnount first and second backllghted electronlc camera heads,
orthogonally to each other so as to be perpendicular to har
10 during peripheral scanning of bar 10 through a prescribed
angular displacement. Bar 10 prof'ile plot scan is shown in
FIaS. lA and 2 as 90 rotation by scanner 12. This will
gather enough camera signals to permi~, later plotting of
180 lateral proflle of bar 10. A 180 pro~lle plot is
qulte usef'ul to a mill operator and a mill control computer
as de~cribed below. Under other scanning requirements f'or
bar si~e mea~urements, the scanning angular displacement
X7-
~3~Z~ii9~1~
may be other than 90. For example, light box 30 and
camera head 31 of the one-dimension gagi.ng sytem shown in
FIG. 1 may be mounted on scanner 12 and rotated to provide
another type of profile plot of bar 10.
First light box 30 is located opposite first
electronic camera head 31 so that when bar 10 intercepts
light from box 30 a bar shadow ~laving a width proportional
: to bar diameter at a first lateral position will be imaged
on first electronic camera head 31. Simi.larly, second light -
box 32 is located opposite second electronic camera head 33
so that when bar 10 intercepts light frorn box 32 a bar
shadow having a wi:dth proportional to bar diameter at a
second la~eral position~ orthogonal to the first, will be
imaged on seoond electronic camera head 33. The arrangement
of first back-lighted camera head, shown in I~IG. 4, and
described below, is typical of both camera heads.
: Each light box 30, 32 is arranged to produce a
light source perpendicular to bar 10 larger than the largest
si~e bar 10 to be gaged in the camera field-of-view. For
example, the camera field-of-view referred to below is 7.62
cm.(three inches) and the light source used therewith is
10.16 cm. (four inches) In addition, the wavelength and
intensity of light boxes 30, 32 must be compatible with the
sensi.tivity characteristi.cs of e:lect;:rorlic came:ra heads 3:1.,
2~ 33. Typically, blue li.ght from a D.C. fired fluorescent
light source is preferrecl for the electronic camera head as
descr:Lbed above.
The first shadow of bar 10, together with
excess light beyond bar 10 edges directed from back light
-68-
1;3L2~9~5
box 30, causes f'irst electronic camera head 31 to generate a
first camera signal. Thls signal consists of a raw camera
pulse mixed with noise which is fed over wire 34 to first
camera electronics 35. As described above in connection
5 wlth FI~. 4, the first camera signal is processed to remove
the noise and pro~uce di~ital bar size and bar position
; signals whLch are fed over cable 36 to computer 27'. Gage
enable and other signals are fed over cable 37 from computer
27 to first camera electronics 35.
~lO ~ ` Simultaneous~ly~, the second shadow of bar lO,
together with excess~light b~eyond bar lO edges directed by
baok~light~box 32,~cause~s~sec~ond eIectronic camera head 33
to~generate~a se~con~d ~camera sLgnal. ~Similarly~ this signal
conslsts of a raw ~oamera pulse rnixed with noise whlch is
15~ fed over wire 38~to second camera electronics 39. The second
- camera signal is~processed to remove the noise and produce
digital bar size and position signals the same as the f'irst
camera signal and these are fed over cable 41 to computer
27'. Gage enable and other signals are fed over cable Llo
from comp~ter 27' to second camera electronics 39.
Computer 27' in the FIG. lA electro-optical bar
gaging system also receives bar lO aim size digital signals
from thumbwheel selector 42 by way of cable 43. Aim size
signals, exemplified as 4.l145 cm. (1.7500 inches), are used
to determine bar 10 profile deviatlon and other purposes
described below. In addition, computer 27' also receives a
bar ].0 compositlon digit,al signal f'rom thumbwheel selector
44 by way of cable 45. Composltlon signal, which is exemplified
as 0.230% and~represents percent carbon in the bar lO, is
-69-
~ 259~S
used as a factor in calculating hot bar aim size from
cold bar aim size and other purposes described below.
~ ' Further, computer 27' also receives appropriate order data
i signals, including date, time and size tolerances for bar
10, from source 46 by way of cable 47~ Alternatively, any
one~or al~l~of~the a~ si~z'e'~s~ignals~,' composition sigrlals, and
other data signals may be supplied by a control system
directly associated with rolling bar lb, dependlng upon the
preference of the bar gaging s'ystem user.
10~ In order~to make~tempe~rature corrections to the
diameter mea~sureme~ts ~o;f moving'ihot bar lO,~a Larld Co.
optiDal pyro ~ er head~48~is~provl~ded ad~acent scanner 12
and~aimed~at~-movlng~hot bar~lO.~ Optical pyrometer head 48
ls~adapted~'to~ gènerate a~hi'g~h-response raw temperature signal
15 ~ which is~fed o'ver~cabl~'49 t~o Land~Co. pyrometer electronics
50. -~The~raw't~empe~a;~`re~si~al is eorrected by seallng and
lineari~zing ciF~eu~t~s in pyromet~er e~lectronics 50 and the
corrected tempe;rature signal, éxemplified as 910C. (1670F.)
ls fed over cable~51 to dlgital indlcator 52. In addition,
the corrected temperature signal is fed over cable 53 to
oomputer 27' where it~ is used to compensate for hot bar 10
shrinkage. ~ ~ ~
Installation problems may preclude a Land Co.
optical pyrometer head 48 and pyrometer electronics 50 from
providing a corrected temperature signal to computer 27' and
indicator 52 with desired'accuracy and rate of response. If
such ls the case, an alternative to the Land Co. pyrometer
'arrangemsnt may be to replace it with an optical field
scanning pyFometer system disclosed as noted above in the
FIG. 1 embodiment.
; ,
: , .
-7-
:
~,
9~S
One other feature of the FIG~ lA bar gaging system
is an automatle reealibrati.on system. As described below,
this feaiure is initiated eaeh time the trailing end of hot
bar 10 is detected leaving mill rolls 11. For this reason,
hot metal deteetor 55 deteets the presenee and absenee of
hot bar 10 and feeds a corresponding signal over wire 56 to
hot metal deteetor electronics 57. A presence/absence
signal is fed over cable 58 to computer 27' where it initiates
t~e automatie recalibration system mentioned abo~e.
All of the scanner position signals, first and
second eamera signals, aim size signal, composition signal,
other signals, temperature signal and hot metal presence/
absence signal fed over respective cables 26, 36, L~l, 43,
45, 47, 53 and 5~ are assimilated by computer 27' to perform
a variety of functions under control of' a-group of computer
off'-line and on-line programs referred to below. One of
these funetions is to generate the seanner start-stop signal
on cable ?8 and the scanner speed control signals on cable
29, both under automatic scanning mode control. ~nother
function is to feed bar diameter data, bar profile de~iation
data overlaid on eommercial tolerance re:E`erences and
operating header data from eomputer 27' over eable 59 to CRT
terminal 60, ancl to accept interaction between a standard
keyboarcl on terrn:lnal 60 and c~ompllter 27' by way o:E' cab:Le 61.
~nother :functj.on of` computer 2'7' is to feed bar
di.arneter data, bar profi.le data over].a3.d on eommerical
tolerance re:E'erences and operat:lng heade:r data from computer
27' over cable 62 to printing terminal 63, and to accept
interactions between a standard keyboard on terminal 63 and
-71-
computer 27 l by way of cable 64. Printing terminal 63 pro-
duces printout 65 which is illustrated in FIG. 3. Still
another function of computer 27 ' is to feed bar 10 profile
data and gaging system histograms over cable 66 to control
system 67 in respo-nse to corresponding request signals fed
back to computer 27 ~ by way of cable 68.
Turning now to FIG. 2, there is shown a cross-
sectional diagram illustrating the lateral profile of bar
10. Dotted circular lines 69 and 70 are illustrative of
maximum and minimum standard commercial tolerances for aim
size diameter. Also illustrated b~ dotted straight lines
are planes A~A, B-B, C-C and D-D which are of particular
interest to a rolling mill operator and a control computer
for determining the roll gap and alignment relationships of
15 mill rolls 11 shown in ~IG. llA. During non-scanning
operations, it is preferred to bring scanner 12 to rest, at
least temporarily so that first camera head 31 and second
camera head 33 will measure the diameters at planes C-C and
A-A, respectively. The A plane dimension of bar 10 is
illustrated at 71 as 4.450 cm. (1. 7520 inches) and the C
plane dimension of bar 10 is illustrated at 72 as 4.442 cm.
(1.7490 inches), the aim size being 4.445 cm. (1.7500 inches)
for illustrative purposes.
During bar scanning operations, it is preferred
25 that second camera head 33 start profile plot scan 73 at
plane B-B, continue counter-clockwise 90 through plane
C-C, and stop at plane D-D. At the same time, first camera
head 31 starts scanning at plane D-D, continues counter-
clockwise 90 through plane A-A and stops at plane B-B.
- 72 -
~5g~5
In this manner, first and second camera heads 31, 33 scan
a 180 lateral peripheral surface of bar 10 and this scan is
plotted from plane B-B to C-C, D-D, A-A and ends back at
B-B. Other methods of scanning may be used. For example,
scanning rotation ma~ be clockwise instead of counter-
clockwise. Also, scanner 12 may start at any plane or
point in between, then scan 90 and return to the starting
position, thereby permitting any 180 portion of bar 10 to
be plotted by rotating cameras 31, 33 only 90.
The resulting profile plot of bar 10 corrected to
cold size is computer printout 65 shown in FIG. 3. Here
bar profile 74 is overlaid on a specific size, size tolerance
and bar position format generated by computer 27 shown in
FIG. lA. The computer-generated format includes an operating
data header; bar pro~ile deviation from the actual cold aim
size~ selected by device 42 in FI~. lA, is the Y-axis
variable; and the scanner 12 angular position is the Y-axis
variable. The Y-axis printout is graduated in 0.0254 mm.
(0.0010 inch) increments above and below aim size dotted
baseline 75 and extends beyond maximum and minimum ~ull-
commerical tolerance reference lines 76, 77. Re~erence
lines 76,77 are printed as dashed lines across the X-axis.
In addition, maximum and minimum half-commercial tolerance
reference lines 78, 79 are printed across the X-axis as
alpha-numeric lines at fifteen angular degree incrernents
of the 180 bar profile plot. At zero and each 45 increment,
the FIG. 2 cross sectiorl plane designations B, C, D, A
and B are printed, while the intervening 15 and 30
increments are so printed relative to the A and C positions.
S91~5
It should be noted that the display on CRT terminal
60 is substantially the same as computer printout 65, with
two exceptions. That is, in addition to the bar profile
deviation plot and computer-generated format, computer 27'
also generates an additional display format of the FIG. 2
dotted-line scanning planes A-A, B-B, C-C and D-D as well
as the actual numerical bar sizes A and C shown as items 71
and 72 in FIG. 2. Second, full tolerance limits are not
displayed if half tolerance is the aim of the system.
Thus, CRT terminal 60 displays bar profile, bar diameter
and bar scanning plane information in a form that is unique
and quite useful to an operator of the bar gaging system
as well as an operator of a rolling mill where the bar gage
is used.
Electronic Camera ~ead
A typical back-lighted first electronic camera
head used in the FIG. lA electro-optical bar gaging system
is also shown in FIG 4 as camera head 31 placed along an
optical axis on the opposite side of bar 10 from light box
30. Camera head 33 and light box 32 are the same as 31, 30
and comprise the second electronic camera head. Depending
on installation requirements and user preference, each first
and second electronic cameras may include a telecentric lens
85~, an image dissector tube 90', photocathode calibration
masks 94', 95'~ focus and de~lection coll assembly 93', and
additional shielding, all as described above with respect to
FIG. 4.
-74-
Si9~
Camera Electronics
.
Typical camera electronics used in the present
electro-optical bar gaging system is also shown in FIG. 4 as
first camera electronics 35. The second camera electronics
5 39 is a duplicate of first camera electronics 35 except for
bldirectional sweep generator 97 which is shared by both
camera electronics 35, 39. Details of camera electronics
35 ~ 39 may be best understood by referring to FIGS. 4 and 7
; through 13 and the descriptions above for the FIG. 1 gaging
system. As a result, first and second camera electronics
35, 39 separately process respective raw camera signals and
produces first and second digital bar si~e pulses and bar
centerline position pulses which are fed over wires 36 and
41 to computer 27' under control of respective signals on
15 wires 37 and 40. Computer correction of each of the bar
pulses is described below.
Computer
A block diagram of the FIG. lA electro-optical bar
gaging system computer 27 ' is illustrated in FIG. 14A.
20 Computer 27 r is a digital system programmed to perform all
of the FIG. 14 functions and the various other functions
described below. As noted above, a commercially availab:le
programmable, or hardwired, mini-computer may be used, or if
desired, computer 27 ' may be shared in overall rolling mill
25 control computer installation. Computer 27 ' is exemplified
herein as a Westinghouse Electric Co., U.S.A~, model w-2500
with an operating system expanded to handle a second bar
si~e pulse and correction thereof, the scanner position
-75-
li25i~1L5
control and profile plot, and for accommodating various
levels of tasks as noted below.
Computer 27' is provided with conventional main
components including input bu~fer 190', Outpllt buf~'er 191',
disc storage 192', disc switches 193', core storage 194',
all communicating by various channels with data processing
unit 195'. Computer 27' operations are controlled sequentially
according to off-line and on-line computer programs 196'.
These comprise: computer maps 197' shown in FIGS. 15, 16A
and 16B, service programs 198', bar gage data program 199',
compensatlon programs 200', calibration progra~ 201', recali-
bration programs 202', profile and position programs 203,
and histogram programs 204', all described below.
All communications with the bar gaging system
computer 27' ~rom external sources are by way of input
; bu~fer 190' which includes means for converting input analog
and digital signals to digital form. These include signals
fed by wires or cables into the computer as follows: first
camera electronics 35 on cable 36; second camera electronics
39 on cable 41; mechanical scanner position 23 on wire 26,
hot metal detector 57 on wire 58; bar temperature 50 on
cables 53, 54; bar aim size 42 on wlre 43; bar composition
44 on wire 45; other data 46 on cable 47; control system 67
on cable 68; CRT terminal 60 on cable 61; and printing
terminal 63 on cable 64.
All communications with bar gaging system computer
27' to external sources are by way of output buffer 191' which
also includes means for converting output signals to digital
-76-
~z~s
and analog ~orm. These include signals ~ed by wires or
cables from the computer as follow~: scanner start-stop 16
on cable 28; scanner speed reference 16 on ca~le 29, control
system 67 on cable 66; ~irst camera electronics 35 on cable
37; and second camera electronics 39 on cable 40.
Individual wires in signal cables have been used
through the drawings and these have been cabled according to
the~r source and function as described above.
CRT termlnal 60 includes a keyboard for operator
int~raction with computer 27'.
Printing terminal 63 inclu~es a keyboard for
operator interaction with computer 27'. Terminal 63 compu~,er
printout 65 includes a plot of bar profile deviation shown
in ~IG. 3, as well as ~abular data listed below.
Generally, it is permissible for both terminals 60
and 63 to plo~ the same data. All interactions ~rom e~ther
keyboard are by way o~ program mnemonics listed, for example,
as follows:
GAGE OFFLINE SYSTEM
MNEMONICS ARE AS FOLLOWS:
HS - HISTOGRAM FOR EACH HEAD
MP ~ BUILDS FIELD OF VIEW COMPENSATION MAPS
PR - ROTATES SCANNER 90 DEGREES AND BUILDS PROFILE TABLE
PL - PLOTS PROFILE TABLE
RP - BUILDS PROFIhE TABLE ON RIGHT MASK DATA
CL - PERFORMS A CALIBRATION CHECK ON LEFT AND RIGHT MASKS
TY PRINTS MAPS, SLOPE & OFFS~T FACTORS, AND MASK VALUES
SC - ROTATES SCANNER T0 DESIRED ANGLE
OF' - ALLOWS ENTRY OF SLOPE AND OFFSET CORRECTION FACTORS
ZE - ZEROES ALL MAPS AND CORRECTION FACTORS !I!CAUTIONI!I
LF - LEFT MASK DRIFT TEST
RT - RIGHT MASK DRIFT TEST (ALSO ALLOWS ENTRY OF WINDOW)
TR - DISK TRANSFER OF GAGE COMMON TO CONTROL SYS. AREA
XI' - EXITS TO MONITOR AND ATTEMPTS TO WRITE COMMON AREA
CONTAINING MAPS, SLOPE AND OFFSET CORRECTION FACTORS,
MASK VALUES, AND WINDOW VALUES TO THE DISK. THE DISK
FILE WILL ONLY BE UPDATED IF DISK SWITCH 12 IS UP.
THIS FILE IS READ FROM THE DISK WHEN THIS TASK (20)
IS CALLED BY THE MONITOR.
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Disc switches I93' include ~witches designated
"switch 10" and "switch 12" in the programs below. These
switches must be turned to "WRITE ENABLE" to update programs
or data on the disc.
Computer Programs
The following table lists ~low charts of indi~
vi.dual and groups o~ programs associated with computer
programs 196' used herein.
COMPUTER PROGRAM
IDENTIFICATION USED
OFF-I,INE ON-LINE
MAPS (197l)
:~ DISC MAP X
CORE MAP X X
SERVIGE PROGRAMS (198')
:~ IDL HANDLER
M:IDL X X
; CD-IDL X X
: EB IDL X X
GAGTSK X
SUBCLL X
GAGTRN X
BAR GAGE DATA PROGRAM (199'~
GAGEIN X X
~ 25 COMPENSATION PROGRAMS (200') X
: CORDAT X
ZERO X
MAPRNT X
GAGTPC X X
CMPNST X X
: CALIBRATION PROGRAM (201')
CALIBR X
~: RECALIBRATION PROGRAMS (202')
RTMASK X
GAGRCL X
LFTMSK X
PROFILE & POSITION
PROGRAMS ~203)
GAGPOS XX X
PROFIL X
RTPROF X
PLOT X
GAGPLT X
: HEADER X
GAGPRO X
HISTOGRAM PROGRAM (204')
GAGHST
PROFILE & HISTOGRAM INTER-
FACE WITH CONTROL SYSTEM X X
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S~5
MAPS (197')
DISC MAP, See FIG. 15: Program address in disc
storage 192' is expanded to handle the add~tional operating
features noted above.
CORE MAP, see FIG. 16A,B: Program address in
hex.adecimal core storage 194' is also expanded to handle the
additional operating features noted above.
SERVICE PROGRAMS tl98')
IDL Handler, including M:ID1, CD:IDL and EB:IDL,
1.0 and GAGTSK, SUBCLL and GAGTRN routines are all as described
above for FIG. 14, except they are simply expanded to handl.e
the additional operating features noted above for FIG. 14A.
BAR GAGE DATA PROGRAM (199')
GAGEIN is an auxiliary subroutine the same as
described above, except ls expanded to accommodate the
additional bar gage data from second camera electronics 39.
COMPENSATION PROGRAMS (200')
GAGMAP, CORDAT, ZERO, MAPRNT, GAGTPC and CMPNST
programs are also the same as described above, except each
is expanded to accommodate the additlonal bar gage data and
correction requirements from second camera electronics 39.
CALIBRATION PROGRAM (201')
CALIBR is an o~f-line program the same as described
above~ except is expanded ko accommodate the additiona~ bar
gage data and calibration requirements from second camera
electronics 39.
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:~LZ59:15
RECALIBRATION PROGRAM (202')
-
RTMASK, GAGRCL and LFTMSK subroutines are also
the same as described above~ except each is expanded to
accommodate the additional~bar gage data and automatic
recalibration requirements from second camera electronics 39.
PROFILE AND POSITION PROGRAMS (203)
ENCNGL is a new auxiliary subroutine appended to
any subroutine requiring the angular position of the bar
diameter gage heads. It reads the position encoder electronics
23, checks validity, puts both the blnary and decimal values
of position into common area, and sets an error flag in the
event of encoder failure.
GAGPOS, a new disc resident subroutine as an
overlayg run under the off-line system and requires operator
interaction. It is invoked by the subroutine SUBCLL through
the mnemonic SC. Its purpose is to drive the scanner to an
angular position input through the terminal keyboard 60, 63.
The following outline will aid in understanding the program:
l. If the target angle is greater than 10 degrees
away from the scan position, full speed voltage is fed over
cable 29 to scan motor controller 16 to drive toward the
target angle. Less than 10 degrees, go to step 3.
2. Continue full speed until scanner is within
10 degrees of target.
3. When within 10 degrees of the target angle,
output 16 is reduced to half-speed voltage.
4. When within 0.3 degrees o~ the target angle,
apply zero volts to controller 16, and exit.
The operator is required to enter the target angle
via the keyboard.
80-
~z~9~s
PROFIL is another new program run under the gage
off-line system. It requires operator intervention. Its
purpose is to scan the camera through a complete g0 degree
cycle and a build profile table FIG. 18 containing t~e
deviations for each 2 degree increment I~DGTL (194'). It
does not plot this data. The PLOT routine PL run under the
off-line system performs this task.
There are three possible error conditions generated.
1. Scan motor failure indicates that the motor
didn't start, or an end of the scan cycle was not found (0 or
90 degrees).
2. Encoder failure - generated if the ready bit
was not generated by the encoder.
3. IDL failure - generated if an IDL transfer
time-out occurs.
RTPROF is still another new program run under the
gage off-line system. Its purpose is to deflect to the
right mask on both cameras while scanning the cameras through
a complete 90 degree cycle and building a profile table
containing the deviations for each 2 degree increment IBDGTl(94).
It does not plot this data. The plot routine PL run under the
off-line system performs this task.
There are three possible error conditions generated.
1. Scan motor failure - indlcates that the motor
didn't start, or an end of the scan cycle was not found (0
or 90 degrees).
2. Encoder failure - generated if the ready bit
was not generated by the encoder.
3~ IDL failure - generated if an IDL transfer
time-out occurs.
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The program deflects each electronic t'R" scan to
right masks 94 in FIG. 5 before beginning the profile and
deflects back to electronlc "C" center scan after the "R"
scan is complete.
PLOT is another new program run under the off-line
gage system. It does not require operator intervention.
Its purpose is to plot the data contained in the profile
table IBDGTl stored in core 194'. The Y-axis is set to 10
rows above the axis and 10 rows below the axis. The scale
, ~ .
10 is floating with a minimum of 0.0051 mm. (0.0002 inch).
Deviation is plotted along~the Y-axis and angular position
of the scanner is plotted along the X-axis in inorements of
4 degrees per column. Data points which are blank or out of
range are represented by a `'#".
GAGPLT, another new on-line program, takes the 90
:s ' ,
element profile table IBDGTl stored in core 194' from a
common area designated MASGAG and compres~ses it to a 60
element table for use as shown in FIG. 19. Each t-able entry
: : :
now represents 3 degrees. It scans the table and determines
~o what Y-axis scale increments to use based on the maximum and
; minimum values in the profile table. This increment is
either 0.0254 mm. (0.001") or o.o508 mm. (0.002"). Next, it
writes the aim size tolerance lines on CRT and printlng
terminals 60, 63. The program then calculates the Y dis-
placement position of each 3 degree table entry and writes a
"*" on the CRT and printing terminals 60, 63 corresponding
to this X and Y location. Finally, it calls the HEADER
prograrn and exits. A bar profile display using the GAGPLT
program is illustrated in ~IG. 3 as printout 65 from printing
terminal 63.
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HEADER, another new on-line program, writes
the bar cold aim size~ carbon and temperature on CRT 60.
Next~ it writes the date, time, maximum tolerance, minimum
tolerance, and out-of-round tolerance on CRT 60 also. Next,
it scans the profile table IBDGTl and calculates the over,
under and out-of-round performance based on the respective
tolerance limits. It then prints these values as in FIG. 3
and exits.
GAGPRO is yet another new program run under the
gage on-line system. It requires no operation intervention.
Its purpose is to scan camera heads 31 and 33 through a
complete 90 degree cycle and build a profile table containing
~; the deviations for each 2 degree increment IBDGTl (194). It
- does not plot this data.
; 15 There are three possible error conditions generated.
1. Scan motor failure - indicates that the motor
dldn't start, or an end of the scan cycle was not found (0
or 90 degrees.)
2. Encoder failure - generated if the ready bit was
not generated by the encoder.
3. IDL failure - generated lf an IDL transfer
time-out occurs.
HISTOGR~M PROGRAM (204')
GAGH~T is an additional new program run under the
on-line and oEf-line gage system. It is actually a modified
version of program 204 and requires operator intervention.
Its purpose is to gather a number of readings from each
camera head 31, 33 while positloned along planes "A-A" and
"C-C" in ~IG. 3 or other location, store the readings in
~83-
Z~5
eore 194' tables IBGDT2 and IBGDT3, and print a histogram
for each eamera head 31, 33 binned at 0.0051 mm. (0.0002
lneh) inerements for a range of ~0.127 to -0.127 mm. (t.005
to -.005 inches) as shown typically ln FIG. 17. In addition,
it ealeulates and prints the mean and standard deviation o~
all readings from each camera head 31, 33. The operator
must enter the number o~ readings desired, the bar aim size,
and request the use of each histogram table IBGDT2 and
IBGDT3, as well as profile table IBGDTl, with control system
67 as shown in FIG. 19.
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