Note: Descriptions are shown in the official language in which they were submitted.
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POSITIONING DEVICE WITH EXTENSIBLE CORD AND METHOD
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part and claims benefit of co-pending
U.S. Application Number 12/214,585, filed June 20, 2008 titled Measuring
Device
with Extensible Cord and Method, and PCT Application Number
PCT/US2009/003690, filed June 18, 2009 titled Measuring Device with
Extensible Cord and Method.
FIELD OF THE INVENTION
This invention relates in general to positioning devices and more specifically
involves a positioning device with an extensible cbrd having a free end, the
cord
free end for positioning a design on a workpiece.
BACKGROUND OF THE INVENTION
Conventional devices for placing a design, such as a CAD that is retained
in a computer, on a workpiece include laser output devices. The design to be
positioned my be a single point or multiple spaced points, such as placement
of a
bore hole or holes, a continuous curve, such as drawing a line, or a three
dimensional surface.
However, laser output devices are extremely expensive, are very sensitive
to shocks and dust, and have limited accuracy on many surfaces. Therefore,
there
are many applications where they are not suitable for use.
Additionally, laser devices must typically be positioned at a known
location and orientation relative to the work piece in order to position the
design
on the workpiece. This typically requires the laser device to be used in a
fixture
with the workpiece. However, there are many applications, particularly one-
time
applications, in which it is highly desirable position the design without the
use of
a fixture.
SUMMARY OF THE INVENTION
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The invention is a positioning device including a computer including a
stored design file, such as a CAD file, for positioning a selected portion of
the
design on a workpiece.
In first embodiment, the device generally comprises a base unit having a
base. The base unit houses an extensible cable including a free end for
placement
by a user at a design point on the workpiece. A turn carriage, rotationally
mounted on the base so as to rotate about a turn axis, includes a main datum
passage and an incoming cable passage between the main datum passage and the
cable free end providing confined passage of the midsection of the cable. The
cable has an alignment position when the local longitudinal axis of the cable
in
the incoming datum passage is radially aligned with the main datum passage.
A turn carriage measuring means measures the rotational position or
change of rotational position of the turn carriage and a cable measuring means
is
coupled to the cable for measuring the length or change of length of the
cable. A
cable tensioning motor adjusts the force required to move the cable free end
away
from the base unit. Cable direction means directs a user to move the cable
free
end toward the portion of the design on the workpiece. The device has an
output
mode for positioning the portion of the design on a workpiece wherein: the
turn
carriage freely rotates to the alignment position responsive to force of the
cable
on the incoming datum passage; and the computer is programmed, responsive to
the turn carriage measuring means, for directing the cable direction means to
direct the user to move the cable free end toward the portion of the design
and;
responsive to the cable measuring means, for directing the cable tensioning
motor
to adjust the tension in the cable sufficiently to indicate when cable free
end is at
a distance to the portion of the design.
The coming cable passage may include pitch measuring means for
measuring the pitch angle or change of pitch angle of the cable.
Another embodiment of the device includes a turn carriage servoed motor
for rotating the turn carriage to follow the cable. Another embodiment
includes a
pitch carriage and pitch carriage servoed motor for rotating the pitch
carriage for
following the cable. Alternately, the servoed motors can also be used to
position
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the device at a target position wherein the incoming datum passage and the
main
datum passage are radially aligned with the portion of the design.
For outputting the design, the device may be placed in a known position
and orientation relative to the workpiece, or the device first be used as an
input
device to measure the relative location and orientation of the workpiece.
Other features and many attendant advantages of the invention will become
more apparent upon reading the following detailed description together with
the
drawings wherein like reference numerals refer to like parts throughout.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view of a room showing a use of the measuring
device of the invention.
Figure 2 is a top, front, right side, partially cut away, perspective view of
selected elements of the base unit of the device.
Figure 3 is a bottom, front, left side, partially cut away, perspective view
of selective elements of Figure 2.
Figure 4A is a front, top, right side perspective view of the cable angular
displacement sensor including a biased main gimbal in the form of a plate
gimbal.
Figure 4B is a back, bottom, left side perspective view of the cable
angular displacement sensor of Figure 4A.
Figure 5 is a front elevation view of the main angular displacement
gimbal of Figure 4A and Figure 4B.
Figure 6 is an enlarged front elevation view of the plate gimbal of Figure
5.
Figure 7 is an enlarged front, top, right side, perspective of the cable
passage assembly of Figures 4 and 5.
Figure 8 is an enlarged cross sectional view of the main gimbal thrust
bearing assembly.
Figure 9 is a perspective schematic of a second embodiment of the cable
angular displacement sensor in the form of contact sensors.
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Figure 10 is a perspective schematic of a third embodiment of the cable
angular displacement sensor in the form of optical sensors.
Figure 11 is a perspective schematic of a fourth embodiment of the cable
angular displacement sensor in the form of a magnetic or electromagnetic
sensor.
Figure 12 is a perspective view of a fifth embodiment of the cable angular
displacement sensor in the form of a moment sensor.
Figure 13 is a flow chart for measuring a surface.
Figure 14 is a front, top, right side perspective view, similar to Figure 4B,
of an alternate embodiment of the main gimbal thrust support in the form of a
wire.
Figure 15 is a cross sectional view, similar to Figure 8, of the wire main
gimbal thrust support of Figure 14.
Figure 16 is an enlarged, exploded, partially-cut-away perspective view of
the wire clamp and gimbal of Figure 15.
Figure 17 is a perspective view of a sixth embodiment of the cable
angular displacement sensor including an off-cable optical sensor.
Figure 18 is a perspective view of a seventh embodiment of the cable
angular displacement sensor including an off-cable laser sensor.
Figure 19 is a perspective view of an eighth embodiment of the cable
angular displacement sensor including a laser sensor and an elastomeric cable
follower.
Figure 20 is an enlarged top view, partially in cross section, of the cable
angular displacement sensor of Figure 19.
Figure 21 is a perspective view of a ninth embodiment of the cable
angular displacement sensor including a two axis, cantilever spring assembly.
Figure 22 is a perspective view of a tenth embodiment of the cable
angular displacement sensor including a magnetic linear encoder.
Figure 23 is bottom, front, left side; partially cut away, perspective view
similar to Figure 3 of selective elements of an alternative embodiment of the
measuring device including only one carriage.
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Figure 24 is bottom, front, left side, partially cut away perspective view of
an alternate embodiment of the device of figure 23.
Figure 25 is perspective diagram showing a device 10 measuring to create
a design.
Figure 26 is a perspective view of device 10 positioning an acquired
design on a workpiece.
Figure 27 is an enlarged perspective view of an alternate cable grip 18
=
incorporating a user interface and cable direction display.
Figure 28 is a diagram of a cable free end positioning function.
DETAILED DESCRIPTION OF THE INVENTION
With reference now to the drawings, there is shown in Figure 1 a
perspective view of a room 800 showing a use of a first embodiment 10A of the
measuring device 10 of the invention. A user 90 uses measuring device 10 to
obtain numerical coordinates, such as polar coordinates, of a plurality of
points in
room 800. By measuring the location of a relatively small number of points in
room 800, measuring device 10 can define all of the desired surfaces 805 in
three-space for purposes of determining the amount or size of flooring, paint,
wall coverings, windows, counter tops, cabinets and other features.
Device 10 may be used in a factory to measure the three-dimensional
location of piping, or machinery details, or other generally difficult-to-
measure
objects.
Surfaces 805 of room 800 include a floor 810, back wall 815, and side
wall 820. A hutch 830 abuts side wall 820. Surfaces 805 of hutch 830 include a
right side wall 835, a left side wall 840, a top surface 845, an upper front
wall
850, a lower surface 855, and a lower front wall '860.
Device 10 generally includes a retractable cable 12 having a midsection
16 and a free end 14; a base unit 20 supporting devices for tracking movement
of
cable 12 and for measuring the length and direction of cable 12, a computer
700,
such as a personal digital assistant (PDA) 701 held by a user 90, and a user
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interface 704 to computer 700 such as an entry pad 704.A.on PDA 701 or key pad
704B on base unit 20.
Housing 102 is protective against dirt and damage and defines an orifice
103 for passage of cable 12. As will be explained in greater detail later,
housing
102 rotates to follow cable 12 as cable 12 is moved. Base unit 20 is adapted
to be
firmly supported by a surface. Framework 25 of base unit 20 is firmly
supported
by a support 40, such as a floor plate placed on the floor or, such as shown
in the
exemplary embodiment, on a first tripod 40F placed on floor 810. Preferably,
base unit 20 is selectively attachable to support 40 for purposes as will be
explained.
A user 90, such as grip user 90G, grips a grip 18 attached to cable free
end 14 and places free end 14 on a point, such as point A on side wall 820,
the
location of which is to be measured by device 10. Grip 18 is attached to cable
12
in a manner so as to not introduce a moment to cable 12 so as to keep cable 12
linear. The distance to point A and the direction to point A are measured by
measuring devices in housing 102.
One or more computers 700 are used for data input, storage, and
processing. In the preferred embodiment shown, grip user 90G uses a hand held
computer 700, such as a personal digital assistant (PDA) 701. PDA 701 contains
a program adapted for receiving and processing data input. A computer program
for performing the functions described herein is readily commercially
available or
can be written by a programmer reasonably skilled in the art or an existing
program can be readily adapted to the specifics of device 10 by a programmer
reasonably skilled in the art. Alternatively, a computer 700 may be located in
base unit 20 or be a separate unit.
In the exemplary embodiment, grip user 90G enters input on entry pad
704A of PDA 701. PDA 701 and base unit 20 have wireless connectivity, such
as radio, such as Bluetooth , and PDA 701 receives the cable measurements from
base unit 20. Other wireless connectivity, such as IrDA (infrared), sound, or
Wi-
Fi could be used. Alternatively, other input and connectivity methods could be
used. A separate cable could be used. Input could be transmitted via measuring
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cable 12. Data connectivity between computer 700, measuring devices, and grip
user 90G allows just one person to be able to operate device 10 and measure
room 800. A second user, not shown, could communicate with computer 700 in
one of the above-described manners or furnish input via port 706 or on entry
or
key pad 704B on base unit 20.
Turning momentarily to Figure 13, there is shown a flow chart for taking
measurement. A user inputs a surface identifier to identify the surface being
measured for associating the measured points with. With cable free end 14 on a
point to be measured on the surface, the user presses a "record" button. The
measurements are recorded. If more points must be input to reconstruct the
surface, then cable free end 14 is moved and additional points are recorded to
memory for that surface. If not, then a new surface identifier is entered and
points on that surface are measured.
In an exemplary use, user 90 places first tripod 40F firmly on floor 810
and attaches framework 25. The program in PDA 701 is activated for receiving
data. Grip user 90G enters an identifier for a surface 805, such as side wall
820,
to be measured. Grip user 90G enters an identifier for type of surface, for
example "planar" for side wall surface 820, places cable free end 14 on a
point,
such as point A, on side wall 820, and presses a record button on PDA 701. The
location of point A is determined by base unit 20 and is transmitted to PDA
701.
This procedure is repeated with points B and C. PDA 701 now has in memory
three points A, B, C that define a plane, of which side wall surface 820 is a
part.
The same procedure is used for other surfaces 805. Additional points on any
surface 805 may be measured. The gathered data can be processed by computer
700 or sent, such as via port 706 or radio, such as with Bluetoothe, to
another
computer for processing.
From the measured data, imaging software, such as computer aided
design (CAD) software reconstructs surfaces 820. Such software is well known
in the art. An example is Geomagic Studio from Geomagic, Inc. Another
software package for processing point data into three dimensions is
RapidFormX0R from INUS Technology, Inc. and Rapidform, Inc.
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Other identifiers for type of surface are used for more complex surfaces.
For a surface identifier such as "smooth curve", the computer program could
"fair" the associated measured points to arrive at the surface configuration.
For
each surface designation, one or more sub-designations may be used. For
example, "edge" or "terminus" is used for designating an edge point or corner
point on a surface respectively. For measuring more complex surfaces, a large
number of points are measured or a "scan" sub-designation is entered and cable
free end 14 is drawn along the surface and points are measured repeatedly
If a surface 805 to be measured, such as hutch left end 840, cannot be
measured by device 10 while mounted on first tripod 40F, such as because the
surface 840 is not in the line of sight from first tripod 40F or cannot
reached by
cable end 14 from first tripod 40F, then an additional tripod, such as second
tripod 40S, is placed in a suitable location for measuring surface 840. Each
tripod 40 includes a reference point, such as point F, S or T, the location of
which, relative to an attached base unit 20, is known. The location of
reference
point S on second tripod 40S is measured by device 10 to establish the spatial
location of second tripod 40S relative to first tripod 40F. Base unit 20 is
detached from first tripod 40F and attached to second tripod 40S. The
reference
point F on first tripod 40F is measured by base unit 20 on second tripod 40S
to
establish the angular orientation of base unit 20 on second tripod 40S
relative to
first tripod 40F. Points are measured from base unit 20 on second tripod 40S.
This tripod jumping pattern can be repeated to measure any surfaces 805.
For example, to measure additional points that are not measurable from second
tripod 40S, first tripod 40F, or another tripod 40T is moved to a suitable
location
for measuring the points. Its reference point F at the new location is
measured,
base unit 20 is detached from second tripod 40S and attached to the moved
first
tripod 40F, and reference point S of second tripod 40S is measured to
establish
the relative position of the new location.
If it is desirable to later add a surface 805 to the data or to later improve
on or correct measured data from a surface 805, it is not necessary to re-
input all
of the measured points. Instead, to add a surface 805, base unit 20 is placed,
as
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described above, in a position to both measure the additional surface 805 and
to
measure a plurality of points on already known surfaces 805. A "re-
orientation"
entry directs computer 700 to use the next measured points from known surfaces
805 to determine the location and orientation of base unit 20 by
triangulation.
The additional points or surface 805 can then be measured and added to the
previously measured data.
Figure 2 is a top, front, right side, partly cut away, perspective view of
selected elements of the base unit 20 of device 10. Figure 3 is a bottom,
front,
left side, perspective view of selected elements of Figure 2. Figures 2 and 3
will
be used to explain the overall functions of device 10. Pertinent elements will
be
later discussed in greater detail. A cable 12 includes a free end 14, a supply
end
13, and a midsection 16 therebetween. Free end 14 is for placement on a point,
the location of which is to be measured, such as point A on Fig. 1. A grip 18
attached to free end 14 of cable 12 is used, such as by gripping by user 90G,
for
positioning free end 14 at a point to be measured.
Base Unit 20 generally includes framework 25 for attachment to floor
support 40, a base 30 attached to framework 25, a turn carriage 100
rotationally
mounted on base 30, and a pitch carriage 200 rotationally mounted on turn
carriage 100.
Framework 25 includes means, such as a plurality of cooperative
connectors 26 for cooperating with support 40 for selectively attaching
framework 25 to support 40.
Base 30 includes a ring 31 attached to and supported by framework 25.
Ring 31 has a circular inner face 32 and a circular outer face 33.
Turn carriage 100 includes a plurality of components attached to a turn-
carriage frame 101. In Fig. 3, frame 101 is only partially shown for clarity.
Turn
carriage 100 includes means 110, such as a plurality of wheels 111, for
rotationally mounting tum carriage 100 on base 30. Wheels 111 including drive
wheel 111D, are mounted on frame 101 and rotationally mount turn carriage 100
on inner face 32 of ring 31 of base 30. Turn carriage 100 is rotationally
attached
to base 30 so as to be rotatable about a yaw axis, such as first axis or turn
axis
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(theta). Turn axis 0 is typically perpendicular to the floor or other support
40 for
base unit 20. Thus, turn axis 0 typically is vertical or substantially
vertical. Turn
carriage 100 can rotate left or right and any number of degrees to align cable
12
in any direction.
Base unit 20 includes power means 190, such as a battery 191 for
powering components. Battery 191 is attached to base unit 20, such as to turn-
carriage frame 101. Power is distributed from battery 191 to the components by
any desirable means, such as power lines, not shown.
Pitch-carriage mounting means, such as a pair of spaced bearings 135 are
attached to frame 101 for rotational mounting of pitch carriage 200.
Pitch carriage 200 includes a plurality of components attached to pitch-
carriage frame 201. In Figure 3, frame 201 is only partially shown for
clarity.
Pitch carriage 200 is rotationally attached to turn carriage 100, such as by
shafts
202 attached to frame 201 and journaled in bearings 135, so as to be rotatable
about a second or pitch axis y (phi) defined by bearings 135. In the exemplary
embodiment, pitch carriage 200 may pitch down at an angle of about 35 and
rotate upward from there through an angle of about 92 for 127 total motion.
A main datum passage 230 is attached to frame 201 and defines an inner,
confined passage relative to frame 201 for midsection 16 of cable 12. In the
exemplary embodiment, a main datum passage device attached to pitch carriage
frame 201, such as pulley 231 rotationally attached to pitch carriage frame
201,
provides main datum passage 230. Main datum passage 230 is where incoming
cable 12 first touches main datum pulley 231 when received from an outer
confined incoming datum passage 339, as will be subsequently described. Main
datum passage 230 provides the first pivot point that is fixed relative to
frame
201 for incoming cable 12. Other embodiments of main datum passage 230
could include a ring orifice or the entrance to a tube or similar opening for
confined passage of cable 12.
In the preferred embodiment shown, second axis qi is perpendicular to and
intersects turn axis 0. Main datum passage 230 is located at, or near, this
intersection. Consequently, the relative polar coordinates p, 0, p of cable
end 14
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may be rather straightforwardly produced from main datum passage 230.
However, other relative axes may be used and the measurements to the point may
then be mathematically transformed as is well known in the art, into any
desired
coordinate system.
A cable supply means 600 is attached to frame 201 and supplies cable 12
from supply end 13 under a predetermined tension to main datum passage 230.
In the exemplary embodiment, cable supply means 600 includes a drum or reel
660, upon which cable 12 is wound and a cable tensioning means 605 including a
cable tension sensor 610 for sensing the tension in cable 12 supplied to main
datum passage 230, and a reel servoed motor 650 coupled to reel 660 such as by
belt 655 for rotating reel 660. Reel mounting means, such as a plurality of
rollers
670, is mounted to pitch frame 201 for supporting reel 660 such that it may
rotate
for storage or release of cable 12. In the exemplary embodiment, cable tension
sensor 610 includes a sensor and a roller pulley 611 that is spring biased to
push
against cable 12 between other cable supports. Sensor 610 senses the location
of
pulley 611 and produces a signal representative thereof. Responsive to the
signal
from tension sensor 610, reel servoed motor 650 rotates reel 660 to maintain
the
predetermined tension. Alternatively, computer 700 receives the signal from
tension sensor 610 and directs reel servoed motor 650 to maintain a desired
tension. In this manner, the desired tension may easily be changed in computer
700 by a user
Other cable tension sensing means well-known in the art could be used,
such as a load cell to measure load on pulley 611.
Cable positioning means 620 attached to frame 201 includes a plurality of
pulleys 622 feeding cable 12 to or receiving cable 12 from a final positioning
pulley 623. Final positioning pulley 623 is mounted on a shaft 630 attached to
frame 201 so as to slide axially along shaft 630 and feed cable 12 to reel 660
such
that cable 12 does not overlap on reel 660.
Cable length measuring means 450 is attached to frame 201 and is
coupled to cable 12 for measuring the length p (rho) or change of length of
cable
12 as free end 14 is moved and placed on a point. Cable length measuring means
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450 produces a signal, such as on line 460, indicative of the length p (rho)
or
change of length of cable 12. Cable length measuring means of various
configurations are well known in the art. In the illustrative embodiment,
cable 12
is partially wrapped around a pulley 455 such that movement of cable 12
rotates
pulley 455. A sensor 457, as is well known in the art, such as an optical
encoder,
translates amount of rotation of pulley 455 to change in cable length and
produces a signal indicative thereof.
Pitch carriage 200 includes an angular displacement sensor assembly 300
attached to frame 201 including an incoming confined cable passage 339 for
cable 12 between main datum passage 230 and cable free end 14. Cable 12 is in
alignment position when the local longitudinal axis 17 of cable 12 at incoming
confined cable passage 339 is aligned with main datum passage 230. As cable
free end 14 is moved from an old point to a new point that is not directly
radially
outward from the old point, cable midsection 16 is displaced angularly in
angular
displacement sensor assembly 300. Angular displacement sensor assembly 300
detects this angular displacement of cable 12 away from alignment position 305
and produces a signal or signals indicative thereof, such as on lines 308 and
309.
Angular displacement sensor assembly 300 will be discussed in greater detail
later herein.
Turn servoed motor assembly 120 rotates turn carriage 100 about turn
axis 0 responsive to the signal from angular displacement sensor assembly 300
indicative of cable displacement about turn axis (0) so as to move angular
displacement sensor assembly 300 toward alignment position 305. As
illustrated,
turn servoed motor assembly 120 includes a turn servoed motor 122 mounted on
turn carriage 100 and a first drive mechanism 125 including a belt 126
connected
to first drive wheel 127 connected to drive wheel*111D interacting with inner
face 32 of ring 31 of base 30 for rotating turn carriage 100 relative to base
30 and
about turn axis O. As used herein, the term "servoed motor" may apply to any
kind of applicable motor actuator such as a servo motor, a stepper motor, or a
hydraulic motor for example.
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Pitch servoed motor assembly 160 couples pitch carriage 200 to turn
carriage 100 for rotating pitch carriage 200 in bearings 135 about pitch axis
cp
responsive to the signal from angular displacement sensor assembly 300
indicative of cable 12 movement about pitch axis p so as to move angular
displacement sensor assembly 300 toward alignment position 305. As shown,
pitch servoed motor assembly 160 includes a pitch servoed motor 162 mounted
on frame 101 and a pitch drive mechanism 165 including a belt 166 connecting
first drive wheel 167 with second drive wheel 168 connected to journal shaft
202
of pitch carriage 200 for rotating pitch carriage 200 in bearings 135.
A turn-carriage measuring means 500 measures the rotational position or
change of rotational position of turn carriage 100 relative to base 30 and
produces
a signal, such as on line 510, indicative thereof. Many such measuring means
are
well-known in the art. In the exemplary embodiment, an optical encoder 520
includes an optical reader 522 mounted on turn carriage 100 for reading an
encoder strip 525 on base 30.
A pitch-carriage measuring means 550 measures the rotational position or
change of rotational position of pitch carriage 200 relative to turn carriage
100
and produces a signal indicative thereof. Many such measuring means are well-
known in the art. In the exemplary embodiment, pitch-carriage measuring means
550 includes an optical encoder 570 including an optical reader 572 mounted on
pitch carriage 200 for reading an encoder strip 575 on arc 140 of turn
carriage
100 and for producing a signal indicative of the pitch on signal line 560.
In this manner, turn and pitch carriages 100, 200 rotate so as to follow the
movement of free end 14 of cable 12 to a new measured point or between an old
measured point and a new point until cable midsection 16 is once again in
alignment position 305 in angular displacement sensor assembly 300. At this
time, the position of the new point or the change in position of the new point
relative to the old point can be determined, such as by computer 700 in
response
to the signals on lines 460, 510, 560 from measuring means 450, 500, and 550.
The measured point's location may be determined from the signals on
460, 510, and 560, for the purpose of reconstructing the measured surface, by
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mathematical means well known in the art. In the exemplary embodiment,
computer 700 interprets the signals on lines 460, 510, and 560 as representing
the
p, 0, and q components of a point P (not shown) in a polar coordinate system.
Because the force of gravity tends to displace the cable midsection 16
downward
along a catenary curve, the measured location of cable free end 14 is not
coincident with point P, but contains an offset dependent on the cable's
extended
length, the cable's orientation relative to the force of gravity, the cable's
density
per unit length, and the cable's tension. Computer 700 determines the offset
from
these known parameters using mathematical means well-known in the art to
determine the measured location of cable free end 14 relative to point P. For
increased accuracy, an accelerometer or other level sensor (not shown) may be
mounted in base unit 20, such as to pitch carriage 200, for the purpose of
determining the cable's precise orientation relative to the force of gravity.
The location signals on distance signal line 460, rotation signal line 510,
and pitch signal line 560 are stored in connection with the measured point.
This
can be done in any desirable manner, such as in a local computer in base unit
20,
not shown, or, as in the illustrative example, transmitted, such as by
Bluetooth ,
to PDA 701.
Signal communication within base unit 30 may be performed in any
desirable manner. The exemplary configuration uses wires. Wires are easily
used for connectivity because the only relative movement between sending
elements and receiving elements is the change in pitch angle 9.
Figures 4-8 are views of an illustrative embodiment of an angular
displacement sensor assembly 300, such as gimbaled angular displacement sensor
assembly 300G, including a biased main gimbal 310 in the form of a plate
gimbal. Nine other embodiments of angular displacement sensor assembly 300
are shown in later figures and described therewith. Angular displacement
sensor
assembly 300 is attached to second frame 201 and includes a confined incoming
datum passage between main datum passage 230 and cable free end 14 wherein
cable 12 is in alignment position 305 when the local longitudinal axis 17 of
cable
12 is aligned with datum passage 230. Angular displacement sensor assembly
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300 senses the angular displacement of cable 12 away from alignment position
305 and produces a displacement signal, such as on lines 308, 309 indicative
thereof. The displacement signal instructs turn servo motor 122 and/or pitch
servo motor 162 to move turn carriage 100 and/or pitch carriage 200 such that
cable 12 is returned to cable alignment position 305.
Figure 4A is a front, top, right side perspective view of the cable angular
displacement sensor assembly 3000 including a biased main gimbal 310 in the
form of a plate gimbal attached to a portion of pitch-carriage frame 201.
Figure
4B is a back, bottom, left side perspective view of the cable angular
displacement
sensor assembly 300G of Figure 4A. Figure 5 is a front elevation view of the
angular displacement sensor assembly 3000 of Figure 4A. Figure 6 is an
enlarged front elevation view of main gimbal 310 of Figure 4A and 4B. Figure 7
is an enlarged front, top, right-side perspective view of the cable passage
assembly 330 of Figures 4A, 4B and 5. Figure 8 is an enlarged cross sectional
view of main gimbal thrust bearing assembly 370 and biasing assembly 375 of
Figure 5.
Turning for a moment to Figure 6, there is shown an enlarged front
elevation view of main gimbal 310 of Figures 4 and 5. Main gimbal 310 is a
planar, two axis biased gimbal comprising an outer gimbal 312 and an inner
gimbal 320. Outer gimbal 312 includes an outer gimbal ring 313 supported by
the inner ends 316 of a pair of outer torsion members 315 on a first gimbal
axis
314. Note that "ring" is used due to gimbal tradition, but this element may be
any functional shape. Bores 318 receive fasteners 319, such as bolts, as seen
in
Figures 4A and 5, that fasten outer ends 317 of outer torsion members 315 to
pitch carriage 200. Inner gimbal 320 includes an inner gimbal ring 321
supported
by the inner ends 326 of a pair of inner torsion members 325 on a second
gimbal
axis 324. Inner torsion members 325 are supported at their outer ends 327 by
outer gimbal ring 313. Outer gimbal ring 313 is free to rotate about first
gimbal
axis 314. Inner gimbal ring 321 is free to rotate about second gimbal axis 324
relative to outer gimbal ring 313 and, thus, may rotate in any direction. Main
gimbal 310 is a biased gimbal, in that gimbal rings 313, 321 are biased to
rotate
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to a neutral position when rotational forces are removed. In main gimbal 310,
the
neutral bias is provided by paired torsion members 315, 325.
Returning to Figures 4, 5, 7 and 8, the other main components of angular
displacement sensor assembly 3000 are a cable passage assembly 330, a gimbal
thrust bearing assembly 370, a biasing assembly 375, a first angular
displacement
sensor 400, and a second angular displacement sensor 420.
Figure 7 is an enlarged front, top, right side, perspective of the cable
passage assembly 330 of Figures 4 and 5. Cable passage assembly 330 is
mounted on sensor arm plate 321S of inner ring 321 (not seen) of main gimbal
310 and rotates inner ring 321 responsive to angular displacement of cable 12
from cable alignment position 305. An arm 360, such as thin tube 361, has an
inner end 362 connected to inner gimbal ring 321 and an outer end 363
including
a bracket 364, best seen in Figure 4B.
An anti-moment gimbal 340, such as a plate gimbal, is mounted on
bracket 364. Anti-moment gimbal 340 is a planar, two axis biased gimbal
similar
to main gimbal 310 and comprises an outer gimbal 342 and an inner gimbal 350.
As best seen in Figure 5, outer gimbal 342 includes an outer gimbal ring 343
supported by the inner ends 346 of a pair of outer torsion members 345 on a
first
gimbal axis 344. Outer torsion members 345 are supported at their outer ends
347 by bracket 364. Inner gimbal 350 includes an inner gimbal ring 352
supported by the inner ends 356 of a pair of inner torsion members 355 on a
second gimbal axis 354. Note that "ring" is used due to gimbal tradition, but
this
element may be any functional shape. Inner torsion members' 355 are supported
at their outer ends 357 by outer gimbal ring 343. Outer gimbal ring 343 may
rotate about first gimbal axis 344. Inner gimbal ring 352 may rotate about
second
gimbal axis 354 relative to outer gimbal ring 343 and, thus, may rotate in any
direction.
Incoming cable passage members 331, including dihedral blocks 332 and
a biased pulley 333, define a confined incoming datum passage, such as
confined
passage 339, for confined passage of midsection 16 of cable 12. Passage
members 331 are mounted on inner ring 352 of anti-moment gimbal 340. Pulley
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333 is mounted on a swinging yoke 334 and biased toward the cable confining
position by a spring 335. This biasing allows pulley 333 to move slightly to
allow for passage of protuberances on cable 12. Of course, there are many
other
manners of accomplishing this confined cable passage 339. For example, instead
of dihedral blocks 332, a second pulley could be used, or a plurality of
rollers
could be used.
Anti-moment gimbal 340 decouples sensor assembly 300G from applying
any moment to cable 12 in confined cable passage 339. Anti-moment gimbal 340
may not be necessary for all types of cable 12.
As seen in Figure 7, a counter mass 368 may be attached to the back side
of inner gimbal ring 321 to counter the mass of arm 360 and cable passage
assembly 330 so as to balance main gimbal 310 to a more planar neutral
position.
As best seen in Figures 3 and 4A, cable 12 is in the alignment position
305 when local longitudinal axis 17 of cable 12 in confined passage 339 is
aligned with main datum passage 230 and main gimbal 310 and anti-moment
gimbal 340 are in the neutral position. With cable 12 in alignment position
305,
the measurement of a point may be taken. Cable free end 14 is then moved to a
new point for measurement. If cable midsection 16 is displaced angularly
during
movement to the new point, midsection 16 exerts a side force against outer
cable
passage members 33] which, through arm 360, exert a moment on inner gimbal
ring 321 of main gimbal 310 so as to rotate it.
Figure 8 is an enlarged cross sectional view of gimbal thrust bearing
assembly 370. Thrust bearing assembly 370 provides a front-to-back pivot point
for inner gimbal ring 321 and also may bias or pre-load inner gimbal ring 321
to
a position out of the planar position. A pivot rod 371 includes a front end
372
and a back end 373. Inner gimbal ring 321 includes a bearing plate 321B
attached to the front of inner gimbal ring 321. Bearing plate 321B includes a
rear
facing pivot seat 322 and a front facing pivot seat 323. The front end 372 of
pivot rod 371 and rear facing pivot seat 322 are adapted such that bearing
plate
321B, and hence inner gimbal ring 321, pivots on front end 372. Preferably,
also,
pivot rod back end 373 and pitch frame 201 are adapted such that pivot rod
back
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end 373 pivots on pitch carriage 200. These functions can be implemented in
many manners. In the exemplary embodiment, pivot rod front end 372 is curved,
such as being hemispherical. Mounted on or integral with inner gimbal ring 321
and moving therewith are a bearing plate 321B and sensor arm plate 321S.
Bearing plate 321B includes a concave conical pivot seat 322 for receiving
front
end 372 in a pivoting relationship. Pitch frame 201 includes a set screw 203
adjustably threadably engaged in threaded bore 209. Set screw 203 includes a
front-facing, concave, conical pivot seat 203a for receiving pivot rod back
end
373. Pivot rod back end 373 is curved, such as being hemispherical, for
pivoting
in seat 203a. Note that pivot rod 371 pivots on both ends 372, 373 such that
it
only can apply an axial force and, other than its own weight, pivot rod 371
cannot
apply a side load or moment to main gimbal 310. Pivot rod 371 cannot carry any
of the weight of main gimbal 310 or its attachments including anti-moment
gimbal 340.
Because main gimbal 310 may exhibit tensional discontinuities at the
planar position, set screw 203 is adjusted so that inner gimbal ring 321 is
out of
planar with the remainder of main gimbal 310.
Means, such as a biasing assembly 375, may be used to further assure that
inner gimbal ring 321 is positioned at a particular front-to-rear position
against
pivot rod 371. To this end, a compression member, such as spring 376, bears
against pitch frame 201 and inner gimbal ring 321 to bias inner gimbal ring
321
against pivot rod 371. Spring 376 includes a front end 377 and a back end 378.
Pitch frame 201 includes means, such as a set screw 205 adjustably threadably
engaged in threaded bore 204, for bearing on spring front end 377 for
adjusting
the compression biasing of spring 376. Spring back end 378 bears on inner
gimbal ring 321, such on bearing plate 321B, such as on front seat 323
thereon.
Spring 376 and inner gimbal ring 321 may be adapted (not shown), such as with
a
hemispherical cap on spring 376 and a concave conical seat on inner gimbal
ring
321 for receiving the cap, such that spring 376 pivotly bears against inner
gimbal
ring 321 so as to impart no moment to inner gimbal ring 321.
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Although, the terms "front" and "back" are used to conform to the
illustration, thrust bearing assembly 370 can be easily modified to operate in
the
reverse manner with pivot rod 371 in front of inner gimbal ring 321.
Returning to Figs. 4 and 5 showing gimbaled angular displacement sensor
assembly 3000, as best seen in Figure 5, the movement about a first sensor
axis
401 of inner gimbal ring 321 caused by angular displacement of cable 12 is
sensed by first angular displacement sensor 400. The movement of inner gimbal
ring 321 about a second sensor axis 421caused by angular displacement of cable
12 is sensed by second angular displacement sensor 420. In the exemplary
embodiment, first and second angular displacement sensors 400, 420 are optical
encoders as are well known in the art.
First sensor 400 includes a moving portion 405, which rotates with inner
gimbal ring 321, and a fixed portion 415 attached to pitch carriage 200.
Moving
portion 405 includes a radial arm 406 having an inner end 407 connected to
sensor arm plate 321S of inner gimbal ring 321 and an outer end 408 having an
encoder strip 409 thereon. Arm 406 rotates with inner gimbal ring 321 about
first
sensor axis 401. Fixed portion 415 includes an encoder read head 416 attached
to
pitch carriage 200 for reading encoder strip 409. Read head 416 outputs a
signal,
such as on line 308, indicative of rotation of inner gimbal ring 321 about
first
sensor axis 401.
Second sensor 420 includes a moving portion 425, which rotates with
inner gimbal ring 321, and a fixed portion 435 attached to pitch carriage 200.
Moving portion 425 includes a radial arm 426 having an inner end 427 connected
to sensor arm plate 321S of inner gimbal ring 321 and an outer end 428 having
an
encoder strip 429 thereon. Arm 426 rotates with inner gimbal ring 321 about
second sensor axis 421. Fixed portion 435 includes an encoder read head 436
attached to pitch carriage 200 for reading encoder strip 429. Read head 436
outputs a signal, such as on line 309, indicative of rotation of inner gimbal
ring
321 about the second sensor axis 421.
In the exemplary embodiment, the first sensor axis 401 corresponds to
turn axis 8 and second sensor axis 421 corresponds to second axis 9 such that
the
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signal from first sensor 400 may directly be used to control turn servoed
motor
122 to rotate turn carriage 100 toward cable alignment position 305 and the
signal
from second sensor 420 may directly be used to control pitch servoed motor 162
to rotate pitch carriage 200 toward the cable alignment position 305.
If the first and second sensor axes 401, 421 do not correspond to turn axis
0 and second axis 9, then the output signals from sensors 400, 420 are
transposed
by means well known in the art into corresponding turn axis 0 and second axis
9
rotations before being used to command servoed motors 122, 162 for rotation of
turn and pitch carriages 100, 200 toward cable alignment position 305 wherein
a
measurement of a point may be taken.
As seen in Figure 5, flexible anti-dust bag, such at flexible anti-dust bag
419, shown in cross-section, covering first displacement sensor 400, may be
used
to surround sensors to protect them from dust and dirt.
Figure 9 is a perspective schematic of a second embodiment of the cable
angular displacement sensor assembly 300 including proximity or contact
sensors, such as contact sensors 380 mounted to frame 201. Incoming midsection
16 of cable 12 is shown in alignment position 305 wherein the local
longitudinal
axis 17 of cable 12 in confined incoming datum passage 339 is aligned with
main
datum passage 230.
A first pair 380A of contact sensors 381A, 381B, attached to frame 201,
are equally spaced on opposite sides of cable 12 for detecting angular
displacement of cable 12 about a first contact sensor axis perpendicular to a
midline between first sensors 380A. A second pair 380B of contact sensors
381C, 381D, attached to frame 201, are equally spaced on opposite sides of
cable
12 for detecting angular displacement of cable 12 about a second contact
sensor
axis perpendicular to a midline between second sensors 380B. If cable 12 is
angularly displaced so as to touch sensor 381A, sensor 381A produces a signal
on
line 308C1 indicating rotation is required about the first contact sensor axis
in a
first direction. If cable 12 touches sensor 381B, sensor 38IB produces a
signal
on line 308C2 indicating rotation is required about the first contact sensor
axis in
the opposite direction. If cable 12 is angularly displaced so as to touch
sensor
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381C, sensor 381C produces a signal on line 309C1 indicating rotation is
required about the second contact sensor axis in a first direction. If cable
12
touches sensor 381D, sensor 381D produces a signal on line 309C2 indicating
rotation is required about the second contact sensor axis in the opposite
direction.
Depending on the relationship between the first and second contact sensor axes
with 0 and cp, the signals on lines 308C1, 308C2, 309C1 and 309C2 may directly
control turn servoed motor 122 or pitch servoed motor 162 or may be transposed
by means well known in the art into corresponding turn axis 0 and second axis
cp
rotations before being used to command servoed motors 122, 162 for rotation of
turn carriage 100 and pitch carriage 200 toward cable alignment position 305
wherein a measurement of a point may be taken.
Because the slight gaps between cable 12 and sensors 381A-381D
introduce a slight error, contact sensors 380 are dithered about the sensor
axes so
that cable 12 is centered in the alignment position 305 before taking a
measurement. Servoed motors 122, 162 are controlled to dither contact sensors
380.
Figure 10 is a perspective schematic of a third embodiment of the cable
angular displacement sensor assembly 300, including optical sensors 385
mounted to frame 201 for detecting movement of cable 12 from alignment
position 305. Cable 12 is shown in alignment position 305 wherein the local
longitudinal axis 17 of cable 12 in confined incoming datum passage 339 is
aligned with main datum passage 230.
In the exemplary embodiment, each optical sensor 385 includes a light
source 386, some focusing lenses 387A and 387B, and a light sensor 388.
A pitch optical sensor 385A includes light source 386A that emits light
and is disposed on one side of cable 12 and a light sensor 388A for receiving
the
emitted light is disposed on the other side of cable 12. Light sensor 388A may
include a CCD array 389A or other light detector as is well known. One or more
lenses, such as lenses 387A and 387B, may be used to focus or magnify the
light
for accurate reading. Sensor 388A detects when the shadow of cable 12 moves
up or down and produces a signal, such as on line 309D, indicative thereof for
directing pitch
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servoed motor 162 to move pitch carriage 200 so as to return cable 12 to
alignment position 305.
A turn optical sensor 385B includes light source 386B that emits light and
is disposed on one side of cable 12 and light sensor 388B for receiving the
light is
disposed on the other side of cable 12. Light sensor 388B may include a CCD
array 389B or other light detector as is well known. One or more lenses, such
as
lenses 387A, mounted to frame 201, may be used to focus or magnify the light
for accurate reading. Sensor 388B detects when the shadow of cable 12 moves
left or right and produces a signal, such as on line 308D, indicative thereof
for
directing turn servoed motor 122 to move turn carriage 100 so as to return
cable
12 to alignment position 305.
In the exemplary embodiment, the output of optical sensors 385
corresponds directly to movement in 0 and (p. However, other axes may be used
and translated into movement in 0 and cp.
Other types of optical sensors could be used, such as reflecting light off
cable 12 to a light detector.
Figure 11 is a perspective schematic of a fourth embodiment of the cable
angular displacement sensor assembly 300 including a magnetic or
electromagnetic sensor 390. A pitch electromagnetic sensor 390A detects the
proximity of cable 12 and, when cable 12 moves up or down, produces a signal,
such as on line 309E, indicative thereof for directing pitch servoed motor 162
to
move pitch carriage 200 so as to return cable 12 to alignment position 305. A
turn optical sensor 390B detects the proximity of cable 12 and, when 12 moves
left or right, and produces a signal, such as on line 308E, indicative thereof
for
directing turn servoed motor 122 to move turn carriage 100 so as to return
cable
12 to alignment position 305 wherein the local longitudinal axis 17 of cable
12 in
confined incoming datum passage 339 is aligned with main datum passage 230.
Magnetic sensors could also be used to detect the proximity of cable. In
the exemplary embodiment, the output of sensors 390 corresponds directly to
movement in 0 and (p. However, other axes may be used and translated into
movement in 8 and (p.
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Figure 12 is a perspective view of a fifth embodiment of the cable
angular displacement sensor assembly 300 including a moment sensor 395. Tube
360 from the anti-moment gimbal from the confined cable passage 339 is solidly
attached to frame 201. As discussed elsewhere, other means of producing a
confined cable passage 339 such as in Figure 12 are possible. For example
confined passage 339 could be a tube with a close-fitting hole about the outer
diameter of cable 12 that the cable 12 passes through, or could be opposing
rollers that the cable passes between.
When cable 12 is moved up or down, or to the right or to the left though
confined cable passage assembly 330, a side force is transmitted through
confined cable passage 339, as a moment on arm 360, such as thin tube 361.
Arm 360 produces detectable strain on load cells, such as strain gages 396 and
397 mounted on arm 360. Strain gages 396 and 397 produce strain signals which
are processed in a manner well known in the art. Other types of load cells
known
in the art, such as other strain gage arrangements, piezo-resistive-element
load
cells, hydraulic load cells, pneumatic load cells and optical load cells, may
be
used. The strain induced on 360 in the vertical axis is detected by strain
gage 396
and produces a signal, such as on line 309F, indicative thereof for directing
turn
servo motor 162 to move pitch carriage 200 so as to return cable 12 to
alignment
position 305. The strain induced on 360 in the horizontal axis is detected by
strain gage 397 and produces a signal, such as on lines 308F, indicative
thereof
for directing turn servo motor 122 to move carriage 200 so as to return cable
12
to alignment position 305 wherein the local longitudinal axis 17 of cable 12
in
confined incoming datum passage 339 is aligned with main datum passage 230.
Other arrangements of moment-load cell well known in the art may be
applied to the mount end of thin tube 360 at the interface with 201.
Figure 14 is a front, top, right side perspective view, similar to Figure 4B,
of a second embodiment of a main gimbal thrust support assembly 900 including
a thin flexible tension member, such as a line or wire 901, such as piano wire
901P. Figure 15 is a cross sectional view, similar to Figure 8, of thrust
support
assembly 900 for main gimbal 310. Figure 16 is an enlarged, exploded,
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24
partially-cut-away perspective view of the attachment clamp 910 of piano wire
901P to gimbal 310 of Figures 14 and 15. Thrust support 900 replaces thrust
bearing assembly 370 of Figure 8.
Piano wire 901P includes a front end 902, a back end 903 and a
midsection 904. Piano wire 901P has a diameter of about 0.009".
As best seen in Figure 16, attachment means, such as clamp 910, attaches
midsection 904 of piano wire 901P to main gimbal 310, such as to inner gimbal
ring 321 of inner gimbal 320. Inner gimbal ring 321 includes a central bore or
passage 321P therethrough. Preferably, passage 321P is central to gimbal 310.
Clamp base 911 is attached, such as by bolts 912, to inner gimbal ring 321 so
as
to support wire 901P at the center of passage 321P. Base 911 may include a
groove 913 for retaining wire 901P. Clamp moving member 915 attaches to base
911, such as with bolts 919 in threaded bores 914, so as to clamp wire 901P.
Returning to Figures 14 and 15, pitch carriage frame 201 includes a front
support 201f and a back support 201 b for supporting front end 902 and back
end
903 respectively of piano wire 901P. Supports 201f, 201b are spaced
sufficiently, such as about four inches for a 0.009" diameter piano wire 901P,
to
minimize the moment wire 901P can exert on gimbal 310.
In the exemplary embodiment, piano wire 901P is attached as follows.
Wire 901P is threaded through bore 321P in main gimbal 310. Wire front end
902 is passed through a slot or bore in front support 201f, through
compression
spring 922 and is crimped in ferrule 921. Wire back end 903 is passed through
a
slot or bore in back support 201b. Wire 901P is tensioned, such as by pulling
on
back end 903 to partially compress spring 922 and is retained in tension, such
as
by application of back clamp 925. Clamp 910 is then attached to wire 901P as
described above so as to retain main gimbal 310 in the neutral position front
to
back and to resist front to back movement of main gimbal 310 from any applied
thrust forces and return gimbal 310 to the neutral position.
Figure 17 is a perspective view of a sixth embodiment of cable angular
displacement sensor assembly, 300A including off-cable optical sensors 385a,
similar to optical sensors 385 of Figure 10.
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Midsection 16 of incoming cable 12 is shown in the alignment position
305 wherein the local longitudinal axis 17 of cable 12 in confined incoming
datum passage 339 is aligned with main datum passage 230. Cable passage
assembly 330A, includes incoming cable passage member 331 mounted to frame
5 201 on a resilient flexible support member or members, such as on
flexible rods
336. Flexible rods 336 have a fixed end attached to frame 201 and a free end
attached to cable passage member 331. Free end moves sideways in any direction
responsive to a side force. Flexible rods 336 are in a neutral position when
there
is no side force from cable 12 on cable passage member 331. After a side force
10 by cable 12 moves cable passage member 331 and flexible rods 336 to the
side,
flexible rods 336 return to the neutral position when the side force from
cable is
removed. Cable passage member 331 includes confined incoming datum passage
339, such as bore 339a, though which cable 12 passes. The free ends of
flexible
rods 336 are parallel to local longitudinal axis 17 of cable 12. Cable passage
15 assembly 330A may include a projection, such as outward projection 337,
which
parallels local longitudinal axis 17 of cable 12. Confined cable passage 339
aligns with local longitudinal axis 17 of cable 12 with movement of cable 12
out
of alignment position 305 and moves cable passage member 331 in the direction
of cable movement by the bending of flexible rods 336. Optical sensors 385a
20 function in the same manner as sensors 385 of Figure 10 except, instead
of
detecting movement of cable 12 relative to frame 201, they detect movement of
cable passage assembly 330A, such as movement of projection 337, relative to
frame 201.
In the exemplary embodiment, each optical sensor 385 includes a light
25 source, some focusing lenses, and a light sensor.
A turn optical sensor 385A, mounted to frame 201, includes light source
386A that emits light and is disposed on one side of cable 12 and a light
sensor
388A for receiving the emitted light is disposed on the other side of cable
12.
Light sensor 388A may include a CCD array 389A or other light detector as is
well known. One or more lenses, such as lenses 387A and 387B, may be used to
focus or magnify the light for accurate reading. Sensor 388A detects when the
shadow of
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projection 337 moves left or right and produces a signal, such as on line 308,
indicative thereof for directing turn servoed motor 122 to move turn carriage
100
so as to return cable 12 to alignment position 305.
A pitch optical sensor 385B, mounted to frame 201, includes light source
386B that emits light and is disposed on one side of cable 12 and light sensor
388B for receiving the light is disposed on the other side of cable 12. Light
sensor 388B may include a CCD array 389B or other light detector as is well
known. One or more lenses, such as lenses 387A, 387B, mounted to frame 201,
may be used to focus or magnify the light for pitch and turn for accurate
reading.
Sensor 388B detects when the shadow of projection 337 moves up or down and
produces a signal, such as on line 309, indicative thereof for directing pitch
servoed motor 162 to move pitch carriage 200 so as to return cable 12 to
alignment position 305.
In the exemplary embodiment, the output of optical sensors 385a
corresponds directly to movement in 0 and (p. However, other axes may be used
and translated into movement in 0 and cp by methods that are well known.
Off-cable optical sensors 385a have several advantages over on-cable
sensors 385 of Figure 10. First, the length of projection 337 to sensors 385a
amplifies the displacement of cable 12 at confined passage 339 such that
readings
are more easily taken. Second, optical sensors 385a, unlike optical sensors
385,
are not directly exposed to cable 12, which may carry dirt and other
contaminants
that could prevent readings. Also, off-cable optical sensors 385a can be more
easily enclosed and protected from dust and dirt in a flexible bag, such as
flexible
anti-dust bag 999, shown in diagrammatic representation.
Figure 18 is a perspective view of a seventh embodiment of the cable
angular displacement sensor assembly 300A including an off-cable, laser sensor
930
Cable passage assembly 330A functions as described with respect to
Figure 17, above.
A laser 931, or other light source, is mounted to a portion of cable passage
assembly 330A, such as to projection 337, such that laser beam 932 emitted by
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laser 931 parallels local longitudinal axis 17 of cable 12 at confined passage
339.
A laser beam sensor, such as a CCD array 935, is mounted on frame 201. Array
935 receives laser beam 932, detects motion of laser beam 932 away from the
cable alignment position 305 and produces a signal or signals, such as on
signal
lines 308 and 309, indicative thereof for directing turn servoed motor 122 to
move turn carriage 100 so as to return cable 12 to alignment position 305 and
for
directing pitch servoed motor 162 to move pitch carriage 200 so as to return
cable
12 to alignment position 305. A lens or mask 936, attached to projection 337
or
to laser 931, includes a lens or a small orifice 937, for passage therethrough
of
laser beam 932 for producing more narrow beam 933 such that narrow beam 933
produces a smaller dot on CCD array 935, as is well known in the art. Laser
sensor 930 is enclosed and protected from dust and dirt in a flexible bag,
such as
anti-dust bag 999, shown in diagrammatic representation.
Figure 19 is a perspective view of an eighth embodiment of cable angular
displacement sensor assembly 300A wherein cable passage assembly 330A
includes cable passage member 331 mounted to frame 201 on a resilient,
flexible
support member, such as on an elastomeric support tube 338. Elastomeric
support tube 338 is sometimes called a rolling diaphragm. Figure 20 is a
partial,
enlarged, top view, partially in cross section, of cable angular displacement
sensor assembly 300A of Figure 18. A rolling diaphragm, such as elastomeric
support tube 338, allows motion radially, yet resists turning about its
central axis.
Other elastomeric embodiments could also be used, such as a rubber block.
Elastomeric support tube 338 includes a first end 338a connected to frame
201, a second end 338b mounting cable passage member 331 and a flexible wall
338c therebetween. Cable passage member 331 is mounted in second end 338b
of elastomeric support tube 338 such that cable 12 passes through tube 338.
Tube
wall 338c supports tube second end 338b such that it can move relative to
first
end 338a and such that second end 338b movably supports cable passage member
331 such that, as confined cable passage 339 aligns with local longitudinal
axis
17 of cable 12 with movement of cable 12 out of alignment position 305, cable
passage member 331 moves in the direction of cable movement.
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A light source, such as laser 940, is mounted to cable passage member
331 such that laser beam 942 emitted by laser 940 parallels local longitudinal
axis
17 of cable 12 at confined passage 339. A laser beam sensor, such as a CCD
array 945, is mounted on frame 201. Array 945 receives laser beam 942, detects
motion of laser beam 942 away from the cable alignment position 305 and
produces a signal or signals, such as on signal lines 308 and 309, indicative
thereof for directing turn servoed motor 122 to move turn carriage 100 so as
to
return cable 12 to alignment position 305 and for directing pitch servoed
motor
162 to move pitch carriage 200 so as to return cable 12 to alignment position
305.
Alternatively, the movement of a projection (not shown) of cable passage
member 331 and paralleling local longitudinal axis 17 of cable 12 could be
detected by sensors, such as optical sensors 385a described with respect to
Figure
17, to provide signals indicative of cable movement.
Figure 21 is a perspective view of a ninth embodiment of the cable
angular displacement sensor 300A including a two axis, cantilever spring
assembly 950 mount for cable passage assembly 330.
Cantilever spring assembly 950 includes a first axis assembly 952
connected to frame 201 providing for movement of cable passage assembly 330
in a first axis; and further includes a second axis assembly 972 connected to
first
axis assembly 952 providing for movement of cable passage assembly 330 in a
second axis.
First axis assembly 952 includes a stationary frame end 953 mounted to
frame 201, single axis, cantilever spring means with relative movement in a
first
axis, such as first pair of parallel, flat springs 954 each having a first end
955
connected to stationary frame end 953 and a second end 956 connected to first
moving frame 957 such that, as first springs 954 bend, first moving frame 957
can move perpendicular to the plane of flat springs 954 relative to frame 201.
Second axis assembly 972 includes single axis, cantilever spring means
with relative movement in a second axis, such as second pair of parallel, flat
springs 974 each having a first end 975 connected to first moving frame 957
and
a second end 976 connected to second moving frame 977 such that, as second
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springs 974 bend, second moving frame 977 can move perpendicular to the plane
of flat springs 974 relative to first moving frame 957. Thus, second moving
frame 977 can move in both axes.
Cable passage assembly 330 is attached, such as by bracket 364, to
second moving frame 977. Cable passage assembly 330, shown, is like that
shown and described in Figures 4, 5, and 7 and includes a confined cable
passage
339 for passage of incoming cable 12. However, other configurations of cable
passage assembly 330, such as those shown herein, could be used.
Midsection 16 of incoming cable 12 is shown in the alignment position
305 wherein the local longitudinal axis 17 of cable 12 is aligned with main
datum
passage 230. With movement of cable 12 out of alignment position 305, confined
cable passage 339 aligns with local longitudinal axis 17 of cable 12 and moves
cable passage member 331 in the direction of cable movement by the deflection
of springs 954, 974.
A first axis angular displacement sensor 960 detects relative movement of
first moving frame 957 and stationary frame end 953 and sends a signal, such
as
on line 309, indicative thereof. A second angular displacement sensor 980
detects relative movement of second moving frame 977 and first moving frame
957 and sends a signal, such as on line 308, indicative thereof. In response
to
signals in lines 308, 309, servoed motor 122 moves turn carriage 100 so as to
return cable 12 toward alignment position 305 and pitch servoed motor 162
moves pitch carriage 200 so as to return cable 12 toward alignment position
305.
In the exemplary embodiment, displacement sensors 960, 980 are of the
arm-and-reader type as used in the first embodiment of Figures 2-8 and each
comprises an arm attached to one of the relative moving members and extending
toward the other relative moving member and an optical encoder reading
displacement between the end of the arm and the other member.
First axis displacement sensor 960 includes arm 961 projecting from first
moving frame 957 toward stationary frame end 953. An encoder strip 962 on end
of arm 961 is read by encoder read head 963 on stationary frame end 953 or
frame 201 and a signal indicative of the relative movement is output on line
309.
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As an option, a first dash pot, such as first air pot 965, is connected
between the free end of arm 961 and mount 968 mounted on frame 201 and
dampens relative movement of stationary frame end 953 and first moving frame
957. First air pot 965 includes a piston 966 moving in an air cylinder 967, as
is
known in that art. Other types of dampener, such as hydraulic, could be used.
Second axis displacement sensor 980 includes arm 981 projecting from
second moving frame 977 toward first moving frame 957. An encoder strip 982
on end of arm 981 is read by encoder read head 983 on first moving frame 957
and a signal indicative of the relative movement is output on line 308.
As an option, a second dash pot, such as second air pot 985, is connected
between the free end of arm 981 and mount 988 mounted on first moving frame
957 and dampens relative movement of first moving frame 957 and second
moving frame 977. Second air pot 985 is similar to first air pot 965 and
includes
a piston, not seen, moving in an air cylinder 987, as is known in that art.
Other
types of dampener, such as hydraulic, could be used.
Displacement sensors 960, 980 can be any desirable type of displacement
sensor, such as shown herein. Also, other configurations of cantilever spring
assembly 950 are possible. An axis assembly 952, 972 could have just a single
spring. Also, axis assemblies 952, 957 can double back on one another so as to
shorten spring assembly 950.
Figure 22 is a perspective view of a tenth embodiment of cable angular
displacement sensor of the arm and sensor type including a magnetic encoder,
such as magnetic linear encoder 990. Magnetic linear encoder 990 can be
substituted for an optical encoder, such as for encoder 409, 416 of the first
embodiment shown in Figure 4A herein. Magnetic linear sensor 990 includes a
multi-pole magnetic strip 992 on angular displacement arm 991 and an encoder
head 993, including a Hall-effect sensing integrated circuit chip 994 for
sensing
movement of magnetic strip 992 in an axis and producing a signal on line 308
indicative thereof.
A suitable encoder 990 is the AS5311 high resolution magnetic linear
encoder made by AustriaMicroSystems of Schloss Premstaetten, Austria. This
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encoder has a resolution as small as 1.95 m so it can detect minute movements
of
arm 991.
Figure 23 is a bottom, front, left side, partially cut away, perspective
view of selective elements of a single carriage embodiment 10B of device 10 as
was shown and described primarily with respect to Figures 2 and 3. Measuring
device 10B is similar to device 10 in most respects but differs as described
below
from device 10 in that there is only one carriage, such as turn carriage 200.
Many
elements that are mounted on pitch carriage 200 in device 10 are instead
mounted
on turn carriage 100 in device 10B. In the exemplary embodiment, device 10B
includes a first displacement sensor, such as turn sensor 400, and a second
angular displacement sensor, such as pitch sensor, 420. A simplified version
of
device 10B may omit pitch sensor 420. A light pointer, such as measuring laser
pointer 270 producing laser beam 271, is attached to turn frame 201.
Device 10B can measure points in a plane that is close to ring 31 of base
30 and that is perpendicular to turn axis 0. Device 10B can measure these
points
with precision if the pitch axis sensor range is not exceeded or, otherwise,
with
sufficient accuracy for many applications. For example, device 10B can be used
to measure flooring, such as tiles.
Main datum passage 230, cable supply means 600, cable length
measuring means 450, and angular displacement sensor assembly 300 are
attached to frame 101. Although a gimbaled angular displacement sensor 300G
is shown, other angular displacement sensors, such as those shown and
described
herein, could be used.
Cable 12 is in alignment position 305 when the local longitudinal axis 17
of cable 12 at outer confined cable passage 339 is aligned with turn axis (0).
As
cable free end 14 is moved from an old point to a new point that is not
directly
radially outward from the old point, cable midsection 16 is displaced
angularly in
angular displacement sensor assembly 300. Angular displacement sensor
assembly 300 detects this angular displacement of cable 12 away from alignment
position 305 and produces a signal or signals indicative thereof, such as on
lines
308 and 309. Turn servoed motor assembly 120 rotates turn carriage 100 about
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turn axis 0 responsive to the signals from angular displacement sensor
assembly
300 indicative of cable displacement about turn axis (0) so as to move angular
displacement sensor assembly 300 to alignment position 305.
As discussed with respect to device 10; in device 10B, the location of the
measured point is determined from turn-carriage measuring means 500, cable
length measuring means 450, and pitch angle from the signals from angular
displacement sensor assembly 300 indicative of pitch angle, such as on line
309.
Figure 24 is bottom, front, left side, partially cut away perspective view
of an alternate embodiment 10C of the devicelOB of Figure 23. Device 10C has
a single carriage, that is first or turn carriage 100C, including a frame 101
rotationally mounted, such as by wheels 111, on base 30 of base unit 20 so as
to
rotate about turn axis 0 (theta). Most of frame 101 is not shown in Figure 24
for
clarity, but can be seen in Figure 3.
As previously described, main datum passage 230 is attached to turn
carriage 100 for confined passage of midsection 16 of cable 12. In incoming
cable passage assembly 330C is attached to turn carriage 100 and includes a
pair
of incoming cable passage members 331C defining a confined incoming cable
passage 339C between main datum passage 230 and cable free end 14 providing
passage of midsection 16 of cable 12 constrained tangentially to, i.e.
orthogonal
to radials of, turn axis 0. Cable 12 is in an alignment position when local
longitudinal axis 17 of cable 12 in incoming datum passage 339C is radially
aligned with main datum passage 230. Turn carriage 100 freely rotates about
turn axis 0 to the alignment position responsive to tangential force of cable
12 on
members 331C of incoming cable passage 339C.
From main datum passage pulley 231, incoming cable 12 passes over a
plurality of pulleys 455, 611, 622, 623 mounted to frame 101 before being fed
onto cable storage reel 660 rotatably mounted on frame 101 as seen in Fig. 2.
Cable tensioning means 605 attached to base unit 20, such as reel servo motor
650 attached to frame 101, adjusts the force required to move cable free end
14
away from base unit 20. In the exemplary embodiment, reel servoed motor 650
applies a tension to cable 12 by using belt 655 to rotate reel 660. The amount
of
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electric current on line 651 to reel servoed motor 650 determines the torque
of
reel servoed motor 650 and, thus, the tension in cable 12.
In the exemplary embodiment, incoming cable passage assembly 330C
includes cable angle measuring means, such as pitch measuring means 580, for
measuring the angle or change of angle of cable 12 at incoming cable passage
339C in a plane parallel to turn axis 0 and for producing a pitch signal, such
as on
line 560C, indicative thereof. In the exemplary embodiment, a light source 582
disposed on one side of cable 12 emits light, and a light sensor 584 for
receiving
the emitted light is disposed on the other side of cable 12. Light sensor 584
may
include a CCD array or other light detector as is well known. One or more
lenses, not shown, may be used to focus or magnify the light for accurate
reading.
Light sensor 584 detects when the shadow of cable 12 moves up or down and
produces a signal, such as on signal line 560C, indicative thereof.
Although, optical pitch measuring means 580 is shown with reference to
the single carriage positioning device 10C, alternate devices, such as those
shown
in Figures 4a, 10, 11, 14, and 17-21 adapted for a single axis, could be used.
Each of the above-described devices 10A, 10B and 10C has an input
mode wherein it may be used as an input/measuring device and has an output
mode wherein it can be used an output/positioning device. Figure 25 is
perspective diagram showing a device 10 measuring the floor 810 of room 800 to
create a design 760 (Fig. 26) of floor 810, and Figure 26 is a perspective
view of
device 10 positioning a mirror image of the acquired design 760 of floor 810
on
the back of a workpiece 750, such as a sheet of carpet material 751 such that
carpet can be cut to exactly fit floor 810.
In Figure 25, base unit 20 is placed on first support 40F. The user places
base unit 20 in input mode, places cable free end 14 along the edge of floor
810
and measures points as described with respect to Figure 1 along the edge of
floor
810 to define design 760 of outline of floor 810. An elongate extension grip
18E
may be used to place cable end 14 along the floor outline so that the user
does not
need to bend down or crawl. If a portion of floor 810, such as alcove 811, is
not
in line of sight of device 10 on first support 40F, then device 10 is moved to
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second support 40S that is in line of sight of alcove 811 to measure alcove
811 as
described with respect to Figure 1. Measured design 760 of floor 810 is now in
computer 700 and can be used and manipulated as any CAD design. For
example, the measured design may be adjusted for shrinkage or stretching of
material before being positioned on material 751.
In Figure 26, base unit 20 is placed in line of sight of workpiece 750 at
any position and orientation relative to workpiece 750. The position and
orientation can be established by using device 10 to measure known points on
workpiece 750 or by using pre-established set positions for workpiece 750 and
base unit 20.
Using device 10C of Figure 24 as the positioning device, in the output
mode with cable 12 in tension, computer 700 always knows the position of cable
end 14 on workpiece 750 from the turn carriage signal and the cable length
signal
and either the pitch signal or the known height of base unit 20 relative to
workpiece 750. User uses an input device, such as PDA to select a portion 762
of
design 760 to position, such as by marking, on workpiece 750.
The user is directed to move cable free end 14 orthogonally to cable 12
toward selected portion 762 of design 760 by cable direction means, such as
audio signals or direction indication 720 on the display of the PDA 701 (Fig.
1)
or on cable grip 18, as shown in Figure 27. Figure 27 is an enlarged
perspective
view of an alternate cable grip 18C incorporating a user interface 704C and
cable
direction indication 720 in communication with computer 700, such as by
Bluetooth. Cable direction indication 720, such as LEDs 721, directs the user
to
move cable free end 14 to the right or to the left, or up or down or in and
out.
The selected portion 762 of the design may be a single point or may be a
larger
design element, such as arc 764 or line 765.
Turn carriage 100C freely pivots to the alignment position responsive to
force of cable 12 on incoming datum passage 339C.
Computer 700 directs user to move radially in or out until free end 14 is at
the distance to selected point. The preferred method of doing this is by
changing
the tension in cable 12 so as to be discernable to the user. Computer 700
directs
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reel servoed motor 650 to apply a first tension, such as half a pound, to
cable 12
when free end 14 is located less than the distance to selected design portion
762
and a second tension, such as higher tension, such as two pounds, when cable
free
end 14 is at the selected distance and beyond. The user applies a tension
between
these two levels, such as one pound. If the cable is too long, the second
tension
from the motor will exceed the force of the user's hand and pull end 14
inward. If
the cable is too short, the force from the user's hand will exceed the first
tension
and pull end 14 outward. Thus, motor 650 servos cable end 14 to a specific
length corresponding to a point design 760.
Figure 28 is a schematic representation of this portion of the system's
operation. The block marked Angle Sensors 730 represents any combination of
sensors for determining the pitch and yaw of carriages 100, 200 and, hence, of
cable 12, in two dimensions, such as pitch measuring means 580 and first
carriage measuring means 500 of Figure 24. A computer 700, such as PDA 701
of Figure 1, receives signals from the angle sensors. Computer 700 also stores
a
design 760 and a selected portion 762 of the design 760 to be positioned. The
portion of the computer's program marked Design Range Check 732 produces a
signal for directing the user to move cable free end 14 into the range of
angles
encompassed by portion 762 of the design to be positioned. The block marked
Cable Direction Means 734 represents any indication means used to
communicate this direction signal to the user, such as LED's 721 of Figure 27.
The portion of the computer's program marked Design Distance Calculator 736
determines the length of cable necessary to place cable free end 14 on design
760
at the current angle. This sub-program produces a length signal 737. A
comparator block 738 produces a cable tension signal 739 by comparing this
target length signal with the cable's current length signal. Cable tension
motor
650 responds to cable tension signal 739 by placing the corresponding tension
on
the cable. Finally, cable length sensor 450 determines the cable's current
length
signal 460 to complete the feedback loop.
When the indicators 704, 721 show cable free end 14 is at the design
position, the position of cable free end 14 may be indicated, such as by
marking,
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on workpiece 750. Returning to Figure 27, a marking device 50 is attached to
cable 12 for marking the end of cable 14 on planar surfaces. Marking device 50
includes a sliding surface 52 for sliding over workpiece 750 and marker 55 for
marking workpiece 750 at end of cable 14. Marking device 50, as shown,
includes a bore therethrough at end of cable 14 position for receiving a
marker 55
in the form of a marking pen 56. Other markers 55 may be used as desired. For
example, a spring-loaded center punch can be used to mark points for drilling
in
metal.
The user may use interface 704C, such as depressing button 705, to direct
computer 700 to continuous position mode in which computer 700 continuously
directs user to adjacent points on selected design 760. As seen in Figure 27,
in
continuous position mode, the user maintains the tension at the low/high
intersection and moves left or right as directed such that a continuous marked
line
766 of design 760 can be drawn.
As seen in figures 25 and 26, one device 10 may measure room 800 and
the measured design may be sent electronically to a carpet seller where a
second
device 10 positions the design on the carpet where it can be cut and rolled
for
delivery to room 800.
Using device 10B of Figure 23 as the positioning device in the output
mode with design portion selected and cable 12 in tension; computer 700,
responsive to the turn carriage measurement signal on line 510, is programmed
to
direct the cable direction means to direct the grip user to move cable free
end 14
to the selected design portion 762 for marking. As cable 12 is moved by the
user,
turn carriage servoed motor 650 turns turn carriage 100 to track movement of
cable 12 responsive to the turn signal from angular displacement sensor 300.
Cable direction means may also indicate when cable free end 14 is at a
selected
point or within a predetermined distance therefrpm. Computer 700 directs reel
servoed motor 650 to adjust cable tension as described above.
In an alternate method of using device 1013 of Figure 23 as the positioning
device in the output mode with design portion selected and cable 12 in
tension;
computer 700 is programmed to direct turn motor 122 to rotate turn carriage
100
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to a target position wherein incoming cable passage 339 and main datum passage
230 are radially aligned with the selected portion 762 of design 760, to
direct reel
servoed motor to adjust cable tension as described above; and, responsive to
the
displacement signal from angular displacement sensor 400, to direct the cable
direction means to direct the grip user to move cable free end 14 to the
selected
design portion 762 for marking.
Using device 10A of Figures 2 and 3 as the positioning device in
the output mode with design portion selected and cable 12 in tension, computer
700 is programmed, responsive to the turn carriage measurement signal on line
510 and pitch carriage measurement signal on line 560, to direct the cable
direction means to direct the grip user to move cable free end 14 to the
selected
design portion 762 for marking. As cable 12 is moved by the user, turn
carriage
servoed motor 650 turns turn carriage 100 and pitch carriage servoed motor 162
turns pitch carriage 200 to track movement of cable 12 responsive to the turn
and
pitch signals from angular displacement sensor 300. Cable direction means may
also indicate when cable free end 14 is at a selected point or within a
predetermined distance therefrom. Computer 700 directs reel servoed motor 650
to adjust cable tension as described above.
In an alternate method of using device 10A of Figures 2 and 3 as the
positioning device in the output mode with design portion selected and cable
12
in tension, computer 700 is programmed to direct turn servoed motor 122 to
rotate turn carriage 100 and pitch servoed motor 162 to rotate pitch carriage
200
to a target position wherein incoming cable passage 339 and main datum passage
230 are aligned with the selected portion 762 of design 760, to direct reel
servoed
motor to adjust cable tension as described above; and, responsive to the
displacement signal from angular displacement sensor 400, to direct the cable
direction means to direct the grip user to move cable free end 14 to the
selected
design portion 762 for marking.
Distances longer than the length of cable 12 may be measured by
connecting a laser micrometer to the end of cable 12 and holding it, such as
by
grip 18, such that the emitted laser beam is parallel to cable 12 and the beam
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lands on the point being measured. The distance indicated by the laser
micrometer is added to the cable distance to attain total distance.
Another method of measuring points at longer distances is to attach a
distance measuring laser to base unit 20. User 90 may be positioned near the
point to be measured and use means, such as a PDA with Bluetooth to drive the
turn and pitch servos to place the laser light on the point and take a
measurement.
Device 10 can be used to measure artwork or blueprints and then scale up
or scale down or even project the measured points on a surface, such as a
wall.
Cable 12 preferably has a low and known strain. A wire cable of about
one sixteenth inch diameter and having a breaking strength of about 300 pounds
has been used. Temperature, humidity, and level sensors may be included to
improve accuracy. Although cable 12 is shown and described as a traditional
cable having a circular cross section, cable 12 could have a different cross
section, such as rectangular tape or polygonal shape.
From the foregoing description, it is seen that the present invention provides
an extremely convenient and accurate positioning device that can be operated
by a
single user.
In the following claims, the work "pitch" is used in a relative sense and
not in an absolute, earth-reference sense.
