Note: Descriptions are shown in the official language in which they were submitted.
UNIVERSAL CONT~OLLER FOR
MATERI~L DISTRIBUTION DE,VICE
Backqround of the Invention
The present invention is directed generally to the
monitoring and control art and more particularly to a
novel and improved monitoring and control system for
a mobile material distribution apparatus.
Generally speaking, mobile material distribution
devices or apparatus include on-the-road and
off-the-road spreader and sprayer apparatus. Such
apparatus generally require control systems for
controlling the rate of distribution of material by
means of various control valves or other control
members. Examples of such material distribution
apparatus are agricultural fertilizer sprayers andfor
spreaders, as well as machines used in agriculture
for distributing various insecticides, herbicides and
other material. Similarly, over-the-road vehicles
may be utilized to distribute insecticide or
herbicide materials along highways, or to distribute
dust control or binder materials for some road
~2-
surfaces, or for various ice control products.
It will be appreciated that each of the foregoing
applications requires a control arrangement to
control the flow or supply of material fed to a
distribution device for carrying out the actual
spreading or spraying of material on the surface to
be treated~ Examples of such a distribution device
are a spray bar having one or more nozzles for
spraying liquid materials and a rotary broadcast-type
spreader for distributing granular materials.
Generally, the control arangement may employ a
control valve in line with the supply of liquid to be
sprayed by the nozzles, or in return line if desired,
to control the pressure and/or flow to the nozzles.
Alternatively, the control valve may be used as
pilot-type of valve in a hydraulic or other control
system for regulating the speed of one or more pumps
or conveyor drive motors in the case of granular
materials. Other systems may use other electrical or
electromechanical control members for controlling the
rate of delivery of a liquid or a granular material
to the appropriate spray bar or broadcast spreader
for distribution.
In addition to providing for such control functions,
it is also desirable to monitor and display the
distribution rate of material from time to time to
assure proper operation of the apparatus to an
operator. In addition, it is often desirable in such
systems to additionally monitor other factors such as
the remaining quantity of liquid or granular material
remaining in a hopper or supply tank mounted on the
--3--
vehicle, or the pressure and/or flow rate at one or
more supply lines in the case of liquid sprayer
apparatus. It is also desirable to provide for
periodic selectable automatic flushing or cleaning of
the system in a liquid distributoe system.
The prior art has proposed a variety of monitoring
and/or control systems for such material distribution
apparatus. Examples of such systems may be found in
Wilder et al. U.S. Patent No~ 3,344r9331
Oligschlaeger U.S. Patent No. 3,877,645, Steffen U.S.
Patent No. 4,052,003 and Bachman et al. ~.S. Patent
No~ 4,392,611.
We now propose to provide a "universal" or
"programmable" type of monitoring system which is
capable of being provided either as original
equipment or retro-fitted to any of a variety of
different mobile material distribution apparatus.
However, such a universally usable monitoring and
control system would require a great deal of
flexibility. That is, the system must have the
ability to accommodate a variety of different types
of ground speed sensors, flow meters, pressure meters
and other input or monitoring devices, in order to
provide both accurate and useful displays of
apparatus opeeation as well as to provide accurate
and reliable control of material distribution rate.
For example, many types of ground sensor apparatus
are known, from relatively simply mechanical or
electromechanical tachometers to relatively
sophisticated radar-based, "Doppler n speed detection
--4--
systems. Similarly, the control o granular-type
spreaders often requires monltoring and control of a
drive component for a conveyor or like material
delivery structure. Such control would require a
similar rotational speed detector or ntachometer n r
which may be of various mechanical or
electromechanical or even electromagnetic types, and
moreover may be placed at any of a variety of
locations in the drive system of a given apparatus.
That is, such a l'pick-upl' device might be placed
directly adjacent a rotating member of the conveyor
itself, elsewhere back in the drive systemr such as
ad~acent some conveniently-accessible gear or shaft
or other rotating drive or transmission member.
Similarly, the flow of material to nozzles in a
liquid sprayer system may be detected as a function
of pressure in the spray bar, pressure in a return
line, or alternatively, by metering the flow in a
delivery conduit or line to the spray bar. Moreover,
- 20 the choice of the type, number and spacing of nozzles
for liquid sprayers must also be taken into account
in order to properly monitor, display and control the
distribution rate of material.
As a further matter, such a universal monitoring and
control system must further be adaptable to
monitoring and display in terms of either English or
metric units as desired by a particular operator.
Such a system must further be capable of calibration
over a relatively wide range of application rates for
use in distributing various materials at differing
rates for given purposes. Moreover, many materials
require that the density or weight per unit volume of
129~
material also be taken into account in determining
and controlling the distribution rate. Such a system
must also be adaptable to a plurality of types and
numbers of nozzles, and/or broadcast spreader
devices, as well as to varying effective widths of
coverage achieved thereby, in order to properly
monitor and control the distribution rate of material
on a per unit area basis. Additionally, such systems
must be capable of setting in certain predetermined
maximum and minimum desired operating limits, as well
as various alarm limits, so that the operator may
have an observable alarm or warning when operation
fails to fall within such limits. Such warning may
be accompanied by automatic shut-down of one or more
components of the apparatus as well, if desired.
In accordance with the invention, a monitoring and
control system is provided for a mobile material
di~tribution apparatus wherein the rate of material
distribution per unit of area varies as a
predetermined function of the ground speed of the
mobile apparatus and of the rate of operation of
variable rate delivery means for delivering material
at a controllable rate to material distribution means
for distributing the material along the path of
travel of the mobile apparatus; said monitoring and
control system comprising: ground speed sensor means
for developing a ground speed signal corresponding to
the ground speed of the mobile apparatus and delivery
rate sensor means for developing a delivery rate
signal corresponding to a rate of delivery of
material by said variable rate delivery means; said
monitoring and control system including monitoring
--6--
and control circuit means responsive to said ground
speed signal and to said delivery rate signal for
developing a control signal for controlling the
operation of said variable rate delivery means to
achieve and maintain a desired rate of distribution
of material along the path of travel of the mobile
distribution apparatus, said monitoring and control
circuit means further comprising processing means
responsive to said ground speed and delivery rate
signals for producing said control signals and memory
means for storing data and instructions for enabling
said processing means to respond to delivery rate
signals from each of a plurality of different types
of delivery rate sensor means.
Brief Description_o~the Drawin~s
The features of the present invention which are
believed to be novel are set forth with particularity
in the appended claims. The organization and manner
of operation of the invention, together with further
objects and advantages thereof, may best be
understood by reference to the following description
taken in connection with the accompanying drawings in
which like reference numerals identify like elements,
and in which:
Fig. l is a perspective viewr partially diagrammatic
in form, illustrating a tractor-drawn liquid
fertilizer distribution or sprayer apparatus in
connection with which the system of the invention may
advantageously be utilized;
~30~337
-7-
E`ig. lA illustrates a sprayer apparatus;
Fig. lB illustrates an anhydrous ammonia delivery
apparatus;
Fig. lC illustrates a grannular material spreader
apparatus;
Fig. 2 is a diagrammatic respresentation of the
operative connections of a monitor and control
console in accordance with the invention with various
portions of the apparatus of Fig. l;
Fig. 3 is an enlarged front elevation of the face of
a control and monitoring console in accordance with a
preferred form of the invention;
Figs. 4, 5, and 6 are functional block diagrams in
the nature of flow charts~ further illustrating
various aspects of operation of the control and
monitoring system of the invention;
Fig. 7 is a clrcuit schematic of a motor control
circuit in accordance with a preferred form of the
invention;
Figs. 8A and 8B, taken together, form a schematic
circuit diagram of a microprocessor-based monitoing
and control circuit and associated display panel in
accordance with a preferred form of the invention;
and
Fig. 9 is a circuit schematic of a flow meter circuit
--8--
in accordance with a preferred form of the invention.
Detailed Desc~ ion of the Illustrated Embodiment
Referring now to the drawings and initially to Figs.
l and 2, the lnvention will be illustrated and
described herein in connection with the monitoring
and control oE the operation of a liquid distribution
apparatus of the type generally shown in Flg. l. It
will be understood, however, that the system of the
invention is, in accordance with important features
of the invention, useful with any of a number of
different material distribution apparatusr used in a
variety of applications as discussed hereinabove as
such, the invention is by no means limited to the
liquid distribution system illustrated in Figs. l and
2.
Initially turning to Fig. l, a material distribution
~ 20 apparatus in connection with which the invention may
be utili2ed may include a vehicle such as a tractor
10. The Lractor 10 is preferrably provided with a
ground speed sensor, which may take the form of a
radar-type of radar velocity sensor 12. The radar
velocity sensor 12 may take a variety of forms
without departing from the invention. One
particularly advantageous type of radar velocity
sensor is shown and described in U.S. Patent No.
- 4,633,252.
In the embodiment illustrated in Fig. l, the tractor
10 pulls a mobile material distribution apparatus,
here illustrated as including a wheeled tank 14 for
~9C~
` 9
carrying a supply of liquid to be distributed. It
should be understood that the system may include a
hopper or other suitable structure for carrying a
supply of granular material without departing from
the invention. The liquid material may include
liquid fertilizers, herbicides or insecticides to be
sprayed and agricultural operations. Similarly,
granual materials may include various weed control
materials or fertilizers in granular form, or may
include ice control materials for distribution on
roads or highwaysr or the like by an over-road type
of vehicle (not shown) without departing from the
invention.
In the embodiments illustrated in Figs. lA and lB two
types of liquid distribution systems are
schematically illustrated. In Fig. lA a sprayer
system employing a spray bar 15 with a plurality o~
nozzles 15 is illustrated. In Fig. lB, an anhydrous
ammonia (NH3) distribution system employing a
manifold for feeding anhydrous ammonia to be
incorporated into the soil at a plurality of knives
18 is illustrated. However, in a granular-type of
distribution system, as somewhat schematically shown
in Fig. lC, some other material distribution means,
such as one or more broadcast spreaders l9 may be
employed. In such a system, some suitable means such
as a conveyor belt 21 or other delivery apparatus may
be employed to deliver granular material to the
broadcast spreaders 13.
In any event, each of the foregoing material
distribution apparatus employs some material
~9~ 7
- -10-
distribution means for distributing material along
the path of travel of the apparatus, including either
broadcast spreaders (not shown) as just mentioned or
nozzles 16 or knives 18 as just described. Moreover,
each type of apparatus further includes some type of
delivery rate sensor means for developing a delivery
rate signal corresponding to the rate of delivery of
material to the distribution means ~e.g. knives 16~
nozzles 18 or spreader 19). Preferably such delivery
means are controllably variable for varying the rate
at which the material is delivered to the
distribution means thereby.
In the system illustrated in Figs. lA and lB a flow
control valve 20 is utilized as the variable rate
delivery means control element. This flow control
valve 20 is preferably of the motor-driven type,
wherein an electrical motor is arranged to rotate the
valve to any desired position between fully open and
fully closed so as to control rate of liquid
delivered therethrough to the material distribution
means such as nozzle 16 or knives 18. In a granular
type of system as mentioned above, such a flow
control valve might form a control valve for a
hydraulic motor 25 or the like for driving a conveyor
21 or other material delivery means for delivering
granular material to one or more broadcast spreaders
19 .
An additional delivery rate sensor means is also
provided in each of the systems of Figs. lA and lB
for developing a delivery rate signal corresponding
in some predetermined fashion to the rate of delivery
~9q~)~3;37
` ` -11 -
of material by the variable rate delivery means to
the material distribution means. Such variable
delivery rate sensor means may comprise a flow rate
sensor 22 interposed in a fluid line intermediate the
fluid supply and control valve 20. It should be
- recognized that in the solid material type of
delivery syste~ a similar flow meter might be
utilized to measure the flow through a similar
control valve to a hydraulic motor for controlling
conveyor speed. Alternatively, the delivery rate
sensor means may comprise a pressure meter for
sensing the liquid pressure at the manifold 15, that
is, the pressure across the nozzles 16 or knives 18.
Referring briefly to Fig. 2, like reference numerals
indicate the flow meter 20, flow valve 22 and ground
speed transducer or radar apparatus 12. It will be
noted that each of these elements is electrically
coupled for delivering its corresponding sensor
signal or output signal to a control and monitoring
means schematically illustrated as a console 25
having a display and control panel 30.
Also shown in the embodiment illustrated in Fig. 1
and Fig. 2 is a preferred form of operator actuatable
switching apparatus designated generally by reference
numeral 32. This switching apparatus 32 is
preferably configured for easy attachment to a gear
shift or other control lever 34 of the tractor or
other vehicle 10. The switching apparatus 32
includes a power on/off switch 36, and an
automatic/flush/off (AUTO/~LUSH/O~F) switch 38 and
optionally, an audible alert or alarm device 40 such
-12-
as a "sonalert".
In operation, the power switch is utilized to apply
operating power to the control system or control
console 25 as will be more fully described later.
The AUTO/FI.VSH~OFF switch 38 provides a control valve
shut off comand for shutting down valve ~2 in the OFF
position. In the AUTO positionr this switch provides
the console 25 with a command for initiating
automatic control system operation for controlling
the distribution of material in accordance with the
invention, as will be more fully described
hereinbelow. In the FL~SH position, switch 38
provides the control console 25 with a command that
causes the valve 22 to be opened to a predetermined
"flush n po S i tion, for example, for delivering a flow
of water or other cleansing fluid for cleaning the
system after use, or for discharging remaining unused
liquid from the system.
The liquid sprayer system of Fig. lA preferably
utilizes the pressure signal in connection with the
ground speed signal developed by radar or other
ground speed sensor 12 to control the setting of the
valve 20 to achieve the desired material distribution
rate. Accordingly, the addition of a flow rate
sensor 22 provides a separate monitoring function,
that is, monitoring for possible malfunctions of the
system such as plugged nozzles, worn-out nozzles or
leaks in the system~ If such malfunctions occur in
the system of Fig. lA, it will be appreciated that
the measured flow will vary from its expected value,
given the pressure in the system, the setting of
~l~9~ 7
3-
valve 20 and the number of nozzles 16. In a properly
functioning system, therefore the ground speed and
the flow rate will bear some predetermined/ constant
ratio to one another, given these other factors (i.e.
pressure, number of nozzles and selected control
valve setting).
- Accordingly, the flow meter perorms no control
function in the system but merely acts as an
additional "nozzle monitor" so as to warn the
operator of an improperly functioning or inopeLative
nozzle. Nozzles may malfunction either due to
excessive wear or breakage which would cause greater
flow than their nominal flow characteristics or by
becoming plugged or clogged with dirt, debris or
other material. A sudden change in flow rate would
occur due to either sort of malfunction and such a
change would be detected by flow meter ~2. In
contrast, in the anhydrous ammonia distribution
system of Fig. lB, a flow meter 22 is utilized as the
rate delivery sensor means.
In the illustrated embodiment, the monitoring and
control syste~ utilizes the ground speed signal
provided by ground speed sensor 12 as a reference
signal and the distribution rate signal provided by
selected one of flow rate meter or sensor 22, or
pressure sensor 24l as the feedback signal. This
arrangement provides control of the flow control
valve 20 and hence of the distribution rate of
material per unit area by the mobile material
distribution apparatus.
3~ 7
As will be more fully described hereinbelow, the
monitoring and control system includes novel
monitoring and control circuit means, illustrated in
functional block form in Fig. 3 and in circuit
schematic form in Fig. 4. In accordance with the
invention, this monitoring and control circuit means
is responsive to the ground speed signal and the
delivery rate signal for developing a control signal
for controlling the rate of the variable rate
delivery means, such as the setting of control valve
20r to achieve and maintain 3. desired rate of
distribution of material along the path of travel of
the mobile distribution apparatus.
In the exemplary embodiment illustrated herein, the
montoring and control circuit means further include
processing means responsive to the ground speed and
delivery rate signals for producing not only the
control signals, but also for producing further,
display signals corresponding to associated functions
and conditions of the mobile apparatus. In this
regard, and referring briefly to Fig. 2, it will be
seen that a further input 42 to the monitor and
control console 25 is provided for "optional
functionsn. This further input may include a
plurality of inputs, if desired, to monitor
conditions at a plurality of points in the machine or
apparatus to provide suitable display signals for
advising the operator of the status of the associated
functions and conditions during operation~
In accordance with the invention, further memory
means are provided for storing data and instructions
-15-
to be utilized for enabling the processing means to
respond to the delivery rate signals produced by any
of a plurality of different types of delivery rate
sensors. Such data and instructions may include data
and instructions appropriate either to a pressure
type of sensor such as sensor 24 or a flow rate type
of sensor such as sensor 22. Moreover, additional
data and instructions may be included in the memory
means for enabling specific response to any of a
plurality of specific ones of flow sensors and/or
pressure sensors, in accordance with the actual form
of the pressure and/or flow rate signals produced by
each. The processing means preferably further
includes means for identifying a particular type of
delivery rate sensor means coupled with the control
and monitoring circuit, and the processing means is
responsive to the sensor identifying means for
selecting rom the memory means data and instructions
for enabling response to the delivery rate sensor
means identified.
In accordance with the perferred form of the
invention, the above-mentioned memory means includes
first, mask-programmable, non-alterable memory means
for containing certain non-changeable or permanent
constant data, such as unit conversion constants for
converting from metric to English values, from square
feet to acres, and the like~ As will be more fully
explained later with reference to Fig. 4, memory
capacity for these memory functions is found both in
a microprocessor component in the form of onboard
memory, as well as in the form of outboard
non-volatile, electrically programmable memory
9 ~ ~ 7
-16-
components.
A further, non-volative memory means is accessible
only to authorized factory or service programming
personnel for containing changeable conversion
constants including the data and instructionsr as
mentioned above, for enabling response of the system
to any of a plurality of different delivery rate
sensors including various pressure sensors and/or
flow rate sensors.
Finally, the memory means includes a user accessible
non-volatile memory portion or means for receiving
and storing data entered by the user, or on behalf of
the userr for the particular characteristics of the
actual apparatus with which the system is to be
utilized, such as data to "identify" the actual
delivery rate sensor selected for use with the
apparatus. Additionally, the non-volatile memory is
adapted to receive and store other user-selected data
or inputs. Such data may correspond to selection by
the user of either English or metric units for
display. Data for calibration of the system for
operation with a ground speed sensor such as the
radar unit 12, or other ground speed sensor which is
provided on the tractor or other mobile distribution
apparatus may also be entered. Such calibr~tion data
in effect serves to "identify" the sensor to the
processor. The characteristics o~ the distributing
means, such as the orifice size or flow rates of the
nozzles or knives, the rotational speed of broadcast
spreaders, or the like may also be so entered by the
operator. Alternatively, factory or service
3~ 7
-17-
programming may include additional conversion
constants for responding to any of a plurality of
different models of sensors such as ground speed
sensors, from which the user may select, avoiding the
necessity of entering particular data, when one of
these "pre-programmed" sensors is selected for use.
Referring next to Eig. 3, operation of the monitoring
and control system of the illustrated embodiment will
now be described in further detail with reference to
the display and control panel or face 30 of the
console 25.
Referring now more particularly to Fig. 3, the
control console panel 30 includes three "touchn
switches 50, 52 and 54 and a display window 56. The
display window 5~ includes a four-digit display 58
which preferably comprises four seven-se~ment liquid
crystal display (LCD) elements with decimal points.
The display panel also includes a multi-segment bar
graph display, also preferably composed of multiple
LCD segments 60. In addition, a plurality of printed
or otherwise formed permanent markings 62 may be
included in the face plate or panel 30 immediately
above the bar graph display 60. Additional,
preferably LCD, symbols NSETUPn, a check mark, and
"APER" and are also provided to the right~hand side
: of the four~digit display.
Initially, touching the operate/set up switch 50
permits selection of either the SETUP mode for
programming or setting up the monitor for operation
with a particular apparatus, or the selection of
~2~ 7
-18-
operating mode of the console for actual operation
following the setup procedure. In the operate mode,
touching switch 50 while the OFF/AUTO/FLUSH switch 38
is in the FLUSH position provides a command ~or the
flush operation, that is to flush out the system, as
described above. In the operate mode, holding the
switch 50 depressed for approximately three seconds
will cause the control system to enter into the SETUP
mode. In the SETUP mode, touching switch 50 briefly
causes the system and display to move to the next
setup operation in a se~uence which will be explained
below. The identity of each constant being currently
programmed and/or entered to memory is denoted by the
positlon of a cursor, in the form of illumination of
one of the segments of bar graph 60~ An operators
manual indicates which segment of bar graph
corresponds to the programming of which constant or
information into the system.
In the operate mode, the switch 52 is utilized to
decrease the programmed application rate by some
small increment for minor ~on the go" types of
adjustments. In the SETUP mode, switch 52 is used to
select one of the digits 58 to be set to the desired
value and entered (the digit selected will flash on
and off). Each time switch 52 is touched the next
digit 58 to the right will be selected and begin ~o
flash on and off.
Touch switch 54 causes an incremental, "on the go"
increment to be added to the previously programmed
selected application rate. (Switch 52, as mentioned,
causes the same increment to be sub~ ted.) In the
'7
`~ -19-
SETUP mode, the selected digit may be set to any
value by touching the switch 54, or by holding
pressure on the switch 5~ to cause the digit to
increment from zero to nine. When the digit has been
set to the desired value, the switch 52 is utilized
to select the next digit for setting.
Additionally, the switch 50, when touched in the
operate mode causes an immediate return to the
programmed application rate from any incremented "on
the go" application rate previously effected by the
use of switches 52 or 54.
In the SETUP mode, the operator may enter any number
of constantsr in the order as follows, in to the
memory portion of the system, by utilizing the touch
switches 52 and 54 as described above. The desired
application rate is entered first, in pounds per
acre. It should be understood that while the present
description describes entry of constants in English
units, that metric units may be utilized as well
without departing from the invention, since the
system is also programmed to recognize, accept and
operate in terms of metric units of measurement.
Ne~t the operator enters the desired incremental
amounts of change in the application rate which will
be automatically effected in the ~change on the go"
procedure as described above.
The density in terms of weight per unit volume of the
material to be distributed (at a given temperature
and pressure) is next entered by the operator. A
flow sensor constant is generally provided with the
9 ~ 7
-20-
flow meter 22 utilized and is entered next. The ne~t
entry is the effective width of coverage of the
applicator, spray bar or other distribution
apparatus, that is the width over which material is
spread during a single pass over a field or other
area to be treated.
The next constant is referred to as a "system
response" constant and determines the amount of
driving power re~uired by the control valve motor to
make minor adjustments in operation to maintain the
desired application rate. An operator's manual will
specify the number to be entered for a given control
valve 20. The next constant entered by the operator
is a ground speed calibration number which may be
specified by a manual for a given ground speed sensor
or may be determined in a ground speed calibration
procedure described hereinbelow.
Regarding the system response constant, when the
control system is operating correctly, the console
display will show some slight variations from time to
time in the application rate, due to variations in
velocity or ground speed of the apparatus. However,
if the display fluctuates by relatively large
amounts, this indicates that the system response
constant should be decreased. On the other hand, if
the display is slow in responding to a change in
ground speed or application rate (such as a change on
the go entry) or it consistently indicates a rate
other than the desired and entered application rate,
the system response constant should be increased in
value.
9(~ 7
-21-
The ground speed calibration is a number that
essentially matches the ground speed sensor to the
control system. To determine the constant for a
given apparatus, the tractor or other mobile
apparatus is driven over a measured course while the
console monitors the signal produced by the
particular ground speed sensor being used. In this
way the console can determine the correct adjustment
for accomodating this particular sensorO In
operation, the "ground speed" calibration process is
as follows. The system is placed in set-up mode and
the switch 38 is moved to the FLUSH position and
released as the tractor or other apparatus pulls even
with the start of a 400 foot long measured and marked
course preferably over level ground. The measured
course is driven at as constant a speed as possible
and the switch 38 is again pushed and released from
its FLUSH position when the finish of the course is
reachedO Thereupon, the display 58 will indicate the
necessary ground speed calibration number to be
entered.
.~
As indicated above, the position o~ the cursor along
the display bar graph 60 indicates the constant being
displayed in the SETUP mode and, as mentioned above,
each touch of switch 50 moves to the next constant to
be programmed and/or displayed in the following
order:
.
~'3S;)~ 7
-22-
BA~ CURSOR
PO S I T ION ~ONSTANT
APPLI Q TION RATE
~ and - APPLIC~TION RATE
DE~ISITY
FLOW SENSOR CONSTANT
WIDTH
S~STEM RESPONSE
GROU~D SPEED CALIBRATION
In operation, the OFF/AUTO/FLUSH switch 38 should
initially be set to the off position and the ON/OFF
switch 36 on the ON position whereupon the alarm will
be sounded and all of the display segments will be
illuminated for one second. The programmed value for
desired application rate will next be displayed for
one second and the console will enter into the
operate mode showing the current application rate,
which prior to commencing operation will of course be
zero (0). To begin operation, the OFF/AU~O/FL~SH
switch is placed in the AUTO position and the
application of material begins with normal operation
of the sprayer or other apparatus. At this time the
actual application rate being achieved will be
displayed in the digits 58, and after some brief
initial start-up period, this application rate will
generally match the desired pre-programmed
application rate within some small margin of
variation. Each operation of the touch switches 52
or 5~ will cause the application rate to be nchanged
on the go" and the pre-selected increment of increase
or decrease should thereafter be reflected in the
current application rate displayed.
The bar graph 60 located at the top of the display
will indicate the percent of maximum flow being
achieved. In the illustrated embodiment, the maximum
~x~
-23-
flow is fi~ed at ~000 pounds per hour. ThiS bar
graph provides a good indication of the system
stability, and with normal system variations, the bar
should flash one or two barS to each side of the
average display position during application. If the
bar graph appears unstable, it is an indication that
the system response constant must be adjusted as
described above. The APER tapplication rate error)
message will be displayed in the event the control
valve 20 reaches its maXimllm or full open position,
this message will flash at one second intervals and
will be accompanied by a short burst from the audible
alarm. Similarly, the "checkmark'l symbol may be
used, with or without the audible alarm, to provide
any further desired "alarm" function. For example a
hopper or tank level may be mounted and the warning
(checkmark lighted) given when it falls below a given
level~ This "checkmark" warning may also be used
when the "nozzle monitor" function described above
determines that one or more nozzles is worn or
plugged.
Referring briefly to Figs. 8A and 8B, the circuit
schematic diagram of the monitoring and control
circuit of the invention is shown. Various inputs
and outputs to the circuit are indicated at the left
hand side of Fig. 8A. These include inputs 70 and 72
for the OFF and FLUSH signals from the OFF/AUTO/FLUSH
switch 38. Motor control signals for closing and
opening the valve are fed out on outputs 74 and 76
and the valve full open signal is monitored at an
application error (APER) input 78. A signal
frequency Fg from ground speed sensor 12 is received
9~
--2~L--
on input 80 while a signal ~requency FQ from a flow
meter 22 r if utilized, is recieved at input 82. When
a pressure sensor 24 is utilized, its input signal is
connected at both inputs 84, 86 which leave somewhat
different scaling resistors. The process selects one
of these two inputs based upon the voltage level
present on inputs 84, 86. This device of scaling
permits a somewhat greater range of voltage values to
be accomodated with improved resolution. Other
functions of the apparatus such as the level o-E
material in a hopper or tank such as tank 14 may be
monitored by a s~litable sensor coupled to an input
88.
A signal to energize alarm ~0 is produced at output
90. Additional inputs include a 12-volt battery or
other vehicle electrical system input 92, a ground
input 94 and a back lighting voltage input 96 for
back lighting of the display, by means of the
20 schematically illustrated lamp or other suitable
lighting means 98. Inputs 70, 72, 80 and 82 are fed
to suitable input ports of a microprocessor 100 by
way of respective operational amplifiers 102,
preferably of the type LM 2901.
The microprocessor 100 preferably comprises a
microprocessor component of the type generally
designated 8052A~1 or 8032AH of the 8052 family of
microprocessors available, for example, from the
Intel Company. The 8052 contains on-board memory,
while selection of the 8032 processor requires the
addition of a further outboard memory component 102.
Additional non-volatile memory for accommodating
9 O ~ 7
-25-
certain data and information as described above is
provided in the form of a NOVRAM 104, which in the
illustrated embodiment is a unit of the type
generally designated NMC 9346NE. The front panel
switches 50, 52 and 54 also couple with the
microprocessor as illustrated in Fig. 8B.
Referring again to Fig. 8Ar the inputs 78, 84, 86 and
~8 are coupled to the microprocessor 100 by way of an
A to D converter/selector component 106, preferably
of the type generally designated ADC 0833CCN. The A
to D converter 106 responds to a serial data input at
a DI input port (pin 13) from the microprocessor 100
for selecting one of the inputs 78, 8~, 86 and 88r
converting the data on the input to serial, digital
form and ~eeding it back out on serial data output
port (DO-pin 10) to the microprocessor 100. In this
regard, a single serial line 108 is utilized for both
data input and output between the A to D converter
106 and microprocessor 100.
Referring to Fig. 8B, serial data for operation of
the display panel 56 is fed out of the microprocessor
on a line 110 to a DATA input of a display driver
component 112, which in the illustrated embodiment
preferably comprises a component of the type PCF
2111. Interconnections between the display driver
112 and display panel 56 are illustrated. The
positive 12 volt input and ground connections feed
respective voltage regulators ~5, 97 for providing a
suitable regulated positive DC voltages for operation
of the circuit and display. For purposes of
illustrating a preferred embodiment of the invention,
-26-
a motor control circuit with OPEN and CLOSE inputs
and an application error (APER) output, which are
coupled with the like designated inputs and outputs
of the processor circuit of FigO 8, is illustrated in
Fig. 7: Additional limit switches Sl and S~ operate
when the valve 20 reaches its fully open and fully
closed positions. Hence the "APER" line connects to
the "fully open" limit switch Sl.
Additionally, while any of a variety of meter
arrangements may be utilized without departing from
the invention, we prefer to utilize a flow meter
circuit of the type illustrated in Fig. 9, which
provides a flow signal frequency FQ at its output, as
indicated~ to the like-designated input of the
processor circuit of Fig. 8. This circuit generally
measures the pulses produced as a "paddle wheeln
interposed in the flow path rotates relative to an
electromagnetic coil type of sensor placed at an
appropriate position on the exterior of the tube or
conduit adjacent the location of the paddle wheel.
Referring now briefly to Figs. 4 through 6, operation
oE the circuit of Fig. 8 is shown in functional block
form. Referring initially to Fig. 4, the respective
frequency signals from the ground speed sensor 12 and
flow meter 22 are designated as fg and fQ,
respectively. The signal from pressure transducer 24
is a signal voltage designated as "Vin. Both of the
signal frequencies fg (same as Fg above) and fQ (same
as FQ above) are processed in the same manner, being
fed initially to respective period counter functional
blocks 200, 202 with the resultant period-related
~,.29~ t7
-27-
signals f'g and f'Q being fed to respective digital
filter blocks 204, 206. The operation of the digital
filter block is the same as that illustrated and
described in U.S. Patent No. ~,~33~252. The
respective period counters operate at a ~0 hertz
cycle rate, that is in 25,000 microsecond (~5
millisecond) intervals, to count the number of
frequency pulses or "interrupts" in each 25
millisecond interval. In the event the incoming
frequency is less than 40 hertz, the period counter
operates to count the number of 25 millisecond
"interrupts" or cycles during each cycle of the
incoming frequency. These two inversely related
count functions are indicated as Xg and Yg in the
illustrated period counter blocks.
The resultant signal f''g from the digital filter 204
represents a ground speed signal which is fed to one
of two branches for further processing. The first
branch squares the signal in the event a pressure
sensor is used as the feedback signal and the second
branch feeds the ground speed signal directly through
in the event a flow meter utilized for the feedback
signal. A reference ground speed is also indicated
at this branching pointt which comprises the maximum
ground speed, corresponding to full opening of the
control valve 20 in response to the "flush" command.
This "flush" reference is substituted at this point
for f''g when the switch 36 is actuated to the FLUS~
position. This would represent maximum ground speed
at which the system is capable of operation, that is
with the valve 20 full open.
~2~ 7
~28-
The pressure signal Vi, depending on the pressure
sensor selected, flows through one of two similar
functional branches or channels having appropriate
selected gains and a corresponding one of two 8-bit A
to D conversion functional channels. These
"channels" correspond to the two pressure inputs 84,
86 as described above. The resultant digital signal
or "counts" are futher processed at functional block
216 which performs the indicated mathematical
operation on the counts for each of the two channels.
Essentiallyr the Kv constant defines a "pressure
transducer" which produces a pressure signal having a
slope and offset of the form Y=MX+B. The resultant
pressure value Y, is here designated as Pc. The
digital "counts" represent the X termr and the
constants Kv represent the slope term. The constant
VPo represents the voltage offset of the "pressure
transducer". The Kv constant is the number of counts
per volt produced by the selected "pressure
transducer" and forms the A to D conversion constant
of the channelr the Kv 1 constant being for channel
number 1 and the Kv 2 constant for channel number 2.
The selected ground speed signal f''g or (fl~g)2 is
fed to an error junction 218 with the corresponding
selected one of the resultant flow signal f''Q or the
resultant pressure signal Pc. The constant Km is a
scale multiplier or forward gain constant of the
system. The constant K is the match constantr that
is, a constant multiplier for taking into account the
effective spray width or spread width of the
apparatus, the selected distribution rate of
materialr the density of the material, and other such
~9C)~ 7
-29-
constants. When the ~nozzle monitor " function
described above is incorporated, both the Pc and f''Q
signals are used. However, the f "Q signal is
compared with f''g only for "alarm" purposes in this
situation, with the Pc signal alone being used at the
error junction 218 to develop the control signal.
The resultant signal value from the error junction
218 is utilized to drive the motor by way of a phase
lead functional block 220 and a scale multiplier
functional block 222, each of which perform the
functions generally as indicated schematically
therein. The resultant drive error signal is
designated by the symbol Der. The sign of the error
signal determines which wa~ the motor is to be
rotated (i.e., to open or close the valve 20), and
hence which side of the motor drive circuit of Fig. 7
the "open" valve side or the "close" valve side is to
be driven by the error signal Der.
This drive error signal Der is further processed into
a duty cycle controlled signal as indicated
functionally in Fig. 6. Briefly, the Der signal is
loaded in accordance with the block 224 into the bits
of a 16-bit timer functional block 226 in which the
carry over count 228 forms the turnoff signal for the
drive ports, the counter being driven at a one
megahertz clock rate. The loading of the 16-bit
timer or counter block is at the cycle rate of 40
hertz mentioned above, such that the clock counts up
to its full count of 65536, starting from the digital
Der number loaded in. Hence, the drive ports, which
are turned on at each timer interrupt cycle at 40
~7
-30-
hertz intervals, will be turned off when the timer
counts to 65536, which will thereby develop a
variable duty cycle type of drive signal to the
motor. It will be noted that with the 40 hertz cycle
rate the maximum count which may be counted by the
clock is 25,0Q0 counts. This corresponds to the
25,000 microseconds available to the one megahertz
clock signal at a 40 hertz interrupt rate.
Accordingly, with the value of Der at a digital
25,000 or more, the drive will remain at a full or
100% duty cycle. With the value of the error drive
signal between ~ero and 25,000, the motor drive will
be a variable duty cycle. With an error signal value
of zero the motor drive will be always off or a 0
duty cycle.
Referring briefly to Fig. 5 the operation of the
period counter, functional blocks 200 and 202, as
described above, is illustrated in somewhat further
detail in functional block form.
While particular embodiments of the invention have
been shown and described in detail, it will be
obvious to those skilled in the art that changes and
modifications of the present invention, in its
various aspects, may be made without departing from
the invention in its broader aspects~ some of which
changes and modifications being matters of routine
engineering or design, and others being apparent only
after study. As such, the scope of the invention
should not be limited by the particular embodiment
and specific construction described herein but should
be defined by the appended claims and equivalents
~ O ~ ~ 7
thereof. Accordingly, the aim in the appended claims
is to cover all such changes and modifications as
fall within the true spirit and scope of the
invention.
