CA1094039A - Weigh feeder system - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

Disclosed herein is an automatically controlled weigh feeding apparatus including a container prefilled with a substance, a device for discharging the substance from the container at a controllable weight, apparatus for weighing the container and its contents and for producing an electrical signal proportional to that weight, a first amplifier for amplifying the electrical signal, a first analog-digital converter coupled to said first amplifier and a digital computer coupled to said first analog-digital converter for computing the weight of substance remaining in the container.
A second amplifier is coupled to said first amplifier and a ramp off-set circuit which is controlled by the digital computer inputs a second signal to the second amplifier means having a controlled stepping output applied as a second input signal to the second amplifier to maintain the output of the second amplifier within a given selected range of amplitude during one time cycle of operation. A second analog-digital converter interposed between the second amplifier and the digital computer. The digital computer is adapted to compute a corrective signal based on the signal received for controlling the discharge of the substance from the container.

Description

~ 10~40~'39 This invention relates to weigh feeding systems and it is particularly applicable to apparatus for feeding fluid-like material. Systems constructed according to the present invention are particularly adapted, among other possible uses, for accurately weigh feeding a wide variety of substances including dry materials regardless of whether the material is free-flowing, sluggish, or pressure sensitive; and ranging from amorphous powders to flakes, pellets, chunks and even fibers, as well as liquids.
Various control weigh feeding systems have been known in the past, as for example, the system disclosed in Canadian patent No. 1,005,143 and No. 1,021,437 issued Feb.
8, 1977 and November 22, 1977, respectively, to Ronald J.
Ricciardi et al. In accordance with these patents, there is provided a weigh feeding apparatus wherein the discharge rate of a fluid substance from a container is maintained at a pre-determined constant value. The container and its contents are weighed, and an electrical signal is produced which signal has an amplitude proportional to the weight of the container and its contents. This electrical signal, which varies as the contents of the container are discharged, is differentiated and applied to a comparator circuit together with a reference signal, wherefore the output of the comparator circuit may be used to control said discharge rate of the substance as it is fed from the container. The comparator output is applied to a signal generator for producing a motor drive signal for a DC
motor having its output shaft connected to drive a device for discharging the substance from the container. The signal

- 2 ~

11 10~940~39 generator may comprise a pulsing circuit for controlling a pair of SCR's which are disposed in a rectifying bridge circuit connected between an AC voltage source and the input of the DC
motor. Accordingly, the speed of the motor is controlled by the pulsing circuit, which, in turn, is controlled by the algebraic sum of the output signal of a tachometer generator which is coupled directly to the motor shaft, and output signal from the comparator. It can be stated that the above-described apparatus provides an accurate weigh feeding system, whereby the feeding rate may be maintained at a constant value, and wherein the predetermined feeding rate may be adjusted by adjusting the value of the reference signal source.

Additionally, the output of the weighing device may be applied to a pair of differential amplifier circuits, along with a pair of reference voltage inputs, for determining when the contents of the container varies above and below desired maximum and minimum fill levels for the container. That is, circuitry is provided for automatically refilling the container when the weight of the substance therein reaches the desired minimum weight, and for terminating the filling process for the container when the fluid substance therein reaches the desired maximum weight. Such circuitry includes means for maintaining the dis-charge rate of the container at a constant rate equal to the instantaneous rate thereof immediately preceding energization of the filling device for the container. Particularly, the pair of differential amplifier circuits are coupled to a pair of relay driver circuits for controlling a relay circuit to energize the filling device when the substance in the container reaches the minimum weight, and for maintaining that filling device in an _3_ 1~)9~039 energized state until the container is refilled to its maximum desired level. The relay circuit is also coupled to the comparator circuit, for controlling the latter to produce a constant output during the refilling process for the container, thereby maintaining the discharge rate of the container at the value of the particular discharge rate thereof immediately preceding energization of the filling device.
As pointed out in said Canadian patents Nos.
1,005,143 and 1,021,437, in certain installations there exists a possibility of physical forces impinging upon the weigh feeder from an external source, such as wind or air currents, physical contact with the weigh feeder by operating personnel, or the like, for example. These forces cause the weigh feeder to move at a rate that is other than that resulting from the linear discharge of the contents of the container. Because such additional movement, i.e. acceleration, is an error and has no direct relationship to the actual discharge of material from the container, the control system could continue to perform its corrective function utilizing the erroneous output signal for comparison with the fixed set point reference signal derivative. The aforementioned patents disclose one means for preventing such excessive and abnormal movements of the weigh feeder scale from grossly affecting or disturbing ~he normal operation of the system to thereby prevent large excursions of the output feed rate.
The present invention is directed to new improved means for accomplishing the foregoing objectives, as well as additional objectives, as will become apparent as the description proceeds.

1~)9~039 Another feature of the present invention resides in the provision of a new and improved weigh feeder system, which is capable of controlling more operating parameters, which operates faster, which provides a faster responsive action, and which is more accurate as compared to the prior art systems. In addition, the feeder system of the present invention has a memory and is capable of taking into account past errors in the material flow rate and taking corrective action with respect thereto.
Also, the system is capable of disregarding extraneous material flow rate readings, which may be caused by such factors as noise, vibrations, or the like, for example.
In one form of the invention, we provide a new and improved weigh feeding apparatus characterized by a container for a prefilled substance having means for discharging the substance therefrom at a controllable rate. A scale system is provided for weighing the container prefilled with the substance and an electrical circuit serves to produce a first electrical signal proportional in amplitude to the weight, and a high gain amplifier amplifies the electrical signal. An analog-digital converter (ADC) is coupled to the amplifier and a digital computer is adapted to receive pulse signals from the ADC for computing and outputting a signal corresponding to the signal received. Digital-analog converter ramp offset means which is controlled by the computer outputs a controlled stepping signal, that is applied as a second input to the amplifier means to algebraically combine therewith. Each step corresponds to one time cycle of operation, thereby maintaining the output of the amplifier in a given preselected range of amplitude during one 10!~0.'39 time cycle of o~eration. The digital computer as another operation thereof computes a corrective signal based on the signal received, and means coupled between the computer and the means for discharging the substance from the container, serve to control the rate of discharge responsive to the corrective signal.

According to one aspect of the invention, the weigh feeder apparatus further comprises means for inputting into the digital computer a preselected feed rate, and the computer is adapted to store in memory a series of signals recei~ed from the ADC for each of the time cycles of operation and compute a corrective signal by comparing the signals received with the preselected feed rate. According to another aspect o~ the invention, the weight feeding apparatus further comprises an under-weight limit input means to the computer and an over-weight limit input means thereto. The computer, as one operation thereof, causes an underweight or an overweight light to energize when an underweight or an overweight condition exists for longer than some preset period of time. Further, according to another aspect of the invention, the digital computer computes the corrective signal, while disregarding a preselected number of the signals received from the ~DC, which exceed a set limit during one time cycle of operation, when computing the corrective signal.

The invention provides, accordi 21g to another fo~m thereof, a new and improved weigh feeding ar,paratus which is characterized by a container for a prefilled substance anci means for disc rging the substance from the cont:ainer at a controllabl~

~ 109~039 rate of weight loss. A scale is provided for weighing the container prefilled with the substance and an electrical circuit is coupled to the weighing means for producing a first electrical signal proportional in amplitude to the weight determined by the weighing means. A first amplifier amplifies t~ e electrical signal and a first analog-digital converter (ADC) is coupled to the first amplifier and outputs binary words to a digital computer coupled thereto. The digital computer, as one operation thereof, computes a first output signal correspond-ing to the weight of the substance in the container. A second amplifier amplifies a signal received from the first amplifier and a second ADC is coupled to the second amplifier and outputs a ~inary word signal to the digital computer. Digital-analog convexter ramp offset means are provided which receive a signal from the digital computer and outputs a controlled stepping outpu~ which is algebraically combined with the input to the second amplifier, each step correspondin~ to one time cycle of operation, thereby to maintain the output of the second amplifier in a given preselected range of amplitude during one time cycle of operation. An input switch is provided to apply a preselected feed rate value to the computer. The computer, as another operation thereof, stores in memory a series of said signals received from the second ADC for each of the time cycles of operation and computes a corrective signal ~y comparing the signals received with the preselected feed rate value. Coupling means interconnect the computer and the ~eans for discharging the substance from the container, whereby the correcti~e signal serves to control the rate of discharge of the substance from the container. A shaft encoder is coupled to the computer to allow vibration signals generated from the rotating machinery mounted on the scale to be corrected for in the computation of the feed rates.
In still another form of the invention there is provided a weigh feeding apparatus which includes a container for a prefilled substance, means for discharging the substance from the container at a controllable rate, means for weighing the container prefilled with the substance, and means coupled to the weighing means for producing electrical signals proportional to the weight determined by the weighing means.
In addition, the apparatus further includes an analog-digital converter for receiving the electrical signals, digital computer means coupled to the analog-digital converter for computing a corrective signal based on the signals received, and means coupled between the computer means and the means for dis-charging the substance from the container for controlling the rate of discharge responsive to the corrective signal. Further, this weigh feeding apparatus comprises, means for inputting into the computer means a preselected feed rate, said computer means being adapted to store a series of the signals received from the analog-digital converter for a time cycle of operation and computing said corrective signal by comparing the signals received with the preselected feed rate, and said computer being further adapted to maintain the corrected signal constant during the time when a preselected number of the signals received from the analog-digital converter exceeds preselected upper or lower limits, during one time cycle of operation.
There has thus been outlined rather broadly the more important features of the invention in order that the 109403~

detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described more fully hereinafter. Those skilled in the art will appreciate that the conception on which this disclosure is based may readily be utilized as the basis of the designing of other structures for carrying out the various purposes of the invention. It is important, therefore, that this disclosure be regarded as including such equivalent constructions and methods as do not depart from the spirit and scope of the invention.

One embodiment of the invention has been chosen for purposes of illustration and description, and is shown in the accompanying drawings forming a part of the specification, wherein:

' Fig. 1 is a block diagram of the weigh feeder system constructed in accordance with the concepts of the present invention;

Fig. 2 is a gra~hic representation of the output voltage with respect to time of one of the amplifier circuits of the present invention;

Fig. 3 is a graphic representation of the output of a controlled ramp offset circuit of the present invention;

Fig. 4 is a graphic representation of the output of a second amplifier circuit;

Fig. 5 is a graphical representation of the actual measured feed cur~e as compared to the desired eed curve;

109'~039 Figure 6 is a graphic representation of the positional relationship of the shaft encoder with respect to the system noise;
Figure 7 is a graphic representation of the output of the second analog-digital converter with respect to time, before correction for induced system noises;
Figure 8 is a graphic representation of the output of the second analog-digital converter with respect to time, after correction for induced system noises;
Figure 9 is a flow chart of the wait subroutine;
Fig~re 10 is a flow chart of the one second interrupt display subroutine;
Figure 11 is a flow chart of the derive subroutine;
Figuresl2A, 12B and 12C is a flow chart of the main routine of the computer;
Figure 13 is a flow chart of the calculate sub-routine; and Figure 14 is a flow chart of the learn mode sub-routine.
The weigh feeder system of this invention, as shown diagramatically in Fig. 1, includes a feeder assembly indicated generally at 10, which comprises a container 12 with a discharge device connected thereto for feeding the substance 14 out of the container and through a discharge conduit 16. As illustrated, a DC motor 18, connected to a 109~039 gear-reduction device 20 is provided for driving the discharge device. The feeder assembly may comprise an auger mechanism as disclosed in detail in U.S. patent No. 3,186,602 issued June 1, 1965 to Ronald Joseph Ricciardi. The entire feeding assembly, including the container, the discharge device, the motor, and the gear-reduction device is mounted on a scale 22, which may comprise a structure as described in detail in U.S.
patent No. 3,494,507, issued February 10, 1970 to Ronald Joseph Ricciardi.
In accordance with the invention there is provided a detecting device, as for example, a linear variable differential transformer (LVDT) 24, coupled to the scale for providing an electrical signal having an amplitude which is proportional to the weight of the container and its contents.
That is, as the contents of the container 12 are discharged, a relative movement occurs between the windings and the core of the LVDT, thereby causing a varying output voltage pro-portional to the varying weight of the container and its contents. Thus, as the substance is discharged from the container, the LVDT provides an electrical signal which varies in response to such discharge, which may, for example, be a DC voltage with a range of the order of from Q3 volts to ~6 volts when the material in the container drops from its upper level to its lower level. The signal from the LVDT is applied to a summing junction 26 by a conductor 28, through a resistor 30. Also, applied to the summing junction 26 is an offset potentiometer means 32, by a conductor 33 through a resistor 34, to render the signal from the LVDT symmetrical with respect to zero as measured at 38. The output from the summing junction 26 is applied to an amplifier 35, having a gain ~o~o~

potentiometer 36, to produce an output signal at 38, which ranges, for example, from -10 volts when the container 12 is full to a +10 volts when 'he container is empty, as shown by the curve in Fig. 2. The output signal from the amplifier 35 is applied to a conventional analog-digital converter (ADC) 40, by way of a conductor 42, wherein the offset amplified LVDT signal is measured and digitalized and outputted as digital words, corresponding to the total scale weight, i.e. the quantity of material contained in the container 12. Any I suitable type of ADC may be employed such as a 12 bit, Model . No. 124-10 XW 3, as manufactured by Analog Devices, Inc.

In addition, the output signal from the amplifier 35 is applied through a resistor 43 to a second amplifier 44, having a feed back resistor 46, thereby to provide a gain of the order of about a 700 multiple. Applicants have found that a galn of this order is necessary in order to make the desired calculations later in the system, but wîth such a gai.n, the voltage would normally be too high, as a ~ractical matter; for computational use, and therefore, a controlled ra~p offset signal is also applied to a summing junction 47 by a conductor 48 through a resistor 49. This offset signal is provided by a xamp offset digital-analog converter (DAC) 50, which receives controlled digital words or binary bits and converts them to a step-shaped signal, having a frequency corresponcling to one time cycle of operation of the process system, as shown by the curve in Fig. 3. This ramp offset functions iIl cooperation ~-ith the amplifie.r 44 so t.hat a controllecl quantity is subtracted from the input to th~ amplifier, whereby duri one time cvcle of operation t~le outpl~t from the 109~039 amplifier 44 gradually decreases from about +5 volts to about -5 volts. The ramp offset 50 is a fast acting electronic servo (typically 50 microseconds), and is controlled so that between time cycles of operation its output is adjusted one step as shown in Fig. 3. Thus, at the beginning of the next succeeding time cycle, the output from the amplifier 44 is again about +5 volts as shown in Fig. 4. Any suitable type of ramp offset DAC may be employed, such as a 14 bit Model ZD354Ml, having a resolution of 1 part in 10,000, as manu-factured by Zeltex, Inc., for example. The amplifiers 35 and 44 may be of any suitable type such as Model OPO5EJ, as manufactured by Precision Monolithics, Inc., for example.

The output from the amplifier 44 is applied to a conventional 12 bit analog-digital converter (ADC) 52 by a conductor 54, wherein the output signal from the amplifier is measured and digitali~ed. ~he output from the ADC is in the form of digital words corresponding to the scale weight, ~ut greatly amplified.

A binary number system is employed as the code for information handling because of certain advantages hereinafter brought out. Thus, as seen in Fig. 1, the weigh feeder system is provided with a digital computer 56, wllich includes processing, memory and control systems. Any suitable digital computer may be employed such as a micro processor Model IMP16C/300 and memory Model IMP16P/004P, as manufactllred ~y National Semiconductor Corp., for example.

Still referring to Fig. 1, a plurality of inputs are applied to the processor to control the same. A conventional 1~ 0.~9 off-on switch 58 serves to control the main power supply to the processor. A switch 60 is provided whereby the refill sequence may be automatically actuated (switch in "auto") when product level reaches low level, or at any product level (switch in "manual") or, the refill sequence may be bypassed (when switch is in "bypass"). The refill sequence is a procedure wherein the motor speed will not lockout for refill thereby actuating the refill controller until the computer first senses that the scale is undisburbed by forei~n influences and secondly, senses that the feed rate agrees with the set feed rate.
Input switch 62 serves to convert the system between gravi-metric control and volumetric control, as desired. This will be explained more fully hereinafter. A reset total push button switch 64 serves to reset the processor for an entirely new batch of data. Also, there is provided a scale weight switch 66, that inputs into the processor the scale weight, S, which is determined by the size or model of the feeder assembly 10 being employed in the particular installation. This factor is set once and is not adjusted unless a new model or size of feeder assembly is installed.
A motor speed input switch 67 is provided, which is set by the operators at a preselected percent in the range between 0% to 100%, to input into the processor the desired operating speed of the motor when operating volumetrically.
Input switch 68 is actuated by the operator to input the desired feed rate R (LBS./HR) into the processor.
This is a 16 bit digital word, stored in memory, that represents the desired slope of the feed line or curve 70, Fig. 5. Input ~' 0,~9 switch 72 is also actuated by the operator to input the under-weight set point into the processor memory. It represents the selected minimum limit of the feed rate range, as is indicated by the dotted line 74 in Fig. 5. This limit is expressed as a percentage of from 0 to 9.99~ below the desired feed rate R.
Input switch 76 inputs the overweight set point into memory.
It represents the selected maximum limit of the feed range, as is indicated by the dotted line 78 in Fig. 5. This limit also is expressed as a percentage of from 0 to 9.99% above the desired feed rate R.
Still referring to Fig. 1, digital switch 80 is an operator activated switch to input into the memory, the desired minimum or low level of the material in the container 12. The range of this switch is from 0 to 99.9%. Thus, for example, if the operator desires the system to shift into its refill mode when the container 12 is down to 5% of its capacity, he sets the low level switch 80 at 05.0%. Digital input switch 82 is an out of low level switch with a range of from 0 to 99.9% so that the operator can input into memory the desired level for the system to shift out of its refill mode to its normal operative mode. Thus, for example, the operator could set this switch for 90.0%, whereby when the container 12 reaches 90% of its capacity, the system would shift out of its refill mode to its normal operative mode.
In addition, the processor also receives a signal from a shaft encoder 83. This allows a correlation to be made between the shaft angle and the system noises induced by the movement of the machinery mounted on the scale or movement of the product in the storage hopper. This correlation may then be used as a correction factor, subtracting out noise 10~4(~.~9 components due to moving machinery on the scale such as for example, the motor, gear box, augers, as well as movement of the material in the container. The processor 56 is provided with a learn mode input switch 85, which is shiftable between normal operation and learn mode operation. When a new material is going to be processed by the system or when the system is first : installed, the system is set in operation, but instead of dis-charging the substance 14 out of the system, it is collected in a small container, not shown, and retained on the scale 22 so that there is no net loss of weight from the scale. The switch 85 is shifted to its learn mode position. The motor 18 is run throughout its speed range and the shaft encoder 83 senses the shaft angle, at ~he various speeds of rotation, while the input circuit through the LVDT 24 picks up the noise corresponding to the rotational position of the drive shaft and sends out digital signals to the processor, which are stored in memory. After this information has been stored in memory, the small container is removed from the scale and the switch 85 is shifted to its normal operation. Fig. 6 illustrates the positional relation-ship of the shaft encoder 83 with respect to the induced systemnoise for a particular speed during the learn mode of operation.
Fig. 7 illustrates the output of the ADC 52 with respect to time, before it is corrected for the induced system noises.
Processor 56, as another operation thereof, subtracts the system noise stored data from the data received from the ADC 52 to present connected values of this information for processing.
Fig. 8 illustrates the corrected output from the ADC 52 for one time cycle of operation. Any suitable type of shaft encoder may be employed such as a Series 2500, Optical Encoder, as manufactured by Renco Corporation.
The microprocessor 56 has, as an output, a display device 84 which indicates the total feed commanded. This device indicates the total feed asked for by the operators over a relatively long period of time. Thus, the processor, as one operation thereof, receives the selected feed rate R from the input switch 68 and integrates it with respect to the elapsed time and continuously displays the total feed commanded, in pounds. As another output there is provided a display device 86 which indicates the actual total feed dis-charged from the feeder assembly 10. Thus, the processor, as one operation thereof, receives a signal from the ADC 40 corre-sponding to the total scale weight, which indicates the quantity of material remaining in the container. This signal represents the amount of weight of material in the feeder 12.
Any change in this signal, except during refill, represents the amount of material fed. These changes are totalled by the processor to give the actual total feed, in pounds. During refill the amount of material fed is computed by the processor from the reading of the feed rate meter and the time it takes to refill. When refill is completed the signal from the ADC
~0 40 is again used to compute the total amount of material fed.
The operators can compare the actual total feed, as displayed at 86, with the total feed commanded, as displayed at 84, to determine how the system is functioning and, if necessary, take corrective action.
A feed rate display device, such as a four digit meter, 88, for example, shows the actual feed rate in pounds per hour of the feeder assembly. Thus, the processor, as another operation thereof, receives the amplified scale weight signal from the ADC 52 and corrects this signal as pointed out hereinbefore, and then differentiates the signal with respect to time to produce a signal indicative of the present rate of 10~94039 feed. This can be visually compared to the desired feed rate as set by the input switch 68 to determine possible malfunctions in the system.
A scale weight display device, such as a three digit meter 90, for example, is provided to indicate the actual percentage of product remaining in the container 12 on the scale 22. Thus, the processor, as still another operation thereof, receives a signal from the ADC 40 corresponding to the weight on the scale 22 and computes the actual percentage of material remaining in the container 12. Next, there is provided, as another output of the processor 56, a three digit motor speed meter 92 which indicates the actual speed of the motor 18. That is, the processor receives a signal from a tachometer 93, indicating the speed of the motor 18, by a conductor 95 through a conventional analog-digital converter 97, and outputs a motor speed on meter 92. While this speed is usually relatively constant, it may vary to some extent over a long period of time. It is advantageous for the operator to know, as any sudden variations may indicate a blockage of material in the system.
In addition, there are provided operational and warning indicators, such as lights, buzzers, or the like, for example, for purposes of keeping the operators informed. An underweight light 94 indicates when the actuai feed rate, as indicated by the meter 88, falls below the underweight set point 72, and an overweight light 96 indicates when the actual feed rate exceeds the overweight set point 76. That is, when the actual feed rate falls below the line 74, Fig. 5, which is set by the underweight set point switch 72, the underweight 10~403~

light 94 is actuated, and when the actual feed rate is above the line 78, Fig. 5, which is set by the overweight set point switch 76, ~he overweight light 96 is actuated. Preferably there is a preselected time delay period of from about 0 to abou t

3 minutes delay after the feed rate meter 88 indicates an overweight or an underweight condition before the warning lights are actuated. Light 98 shows when the system is in its refill mode, i.e. when the container 12 is being refilled. The light 100 indicates that the system is in its ACRILOK mode. This mode of operation will be explained more fully hereinafter.
Run light 102 indicates that the system is in operation and standby light 104 indicates that the system power has been applied, but all machinery is stopped. The light 106 indicates that the bin 12 is in its low level condition.

A control output 108 from the processor 56 is applied to a digital-analog converter (DAC) 110. Any suitable type of DAC may be employed, such as a 10 ~it Model AD7520L, as manufactured by Analog Devices, Inc., for example. In the DAC, the digital pulses are converted to an analo~ signal, which is applied to the tachometer 93 and an SCR motor control 112.
Any suitable type of motor control may be employed such as Acrison, Inc.'s Model ACRlOOBTG, for example. This controller produces an output which is applied to the motor 18 to control the speed thereof, and thereby control the dischar~e rate of the material from the feeder assembly 10.

In operation, the operator must determine whether he wishes to operate in the volumetric mode or the gravimetric mode. If the volumetric mode is selected, then the operator sets the motor speed switch 67 to the desired motor speed. In lO9-~Q39 this mode of operation, the output of the processor is a digital word conveyed by conductor 108 to the DAC 110. The DAC causes a voltage from 0 to 6 volts to appear on conductor 111 and the SCR motor control adjusts the speed of the DC motor 18 until the output of the tachometer 93 exactly equals the voltage on the conductor 111. While this mode of operation is desirable at certain times, it does not provide as high a degree of accuracy as the gravimetric mode and, consequently, the gravi-metric mode is predominantly employed.
In operation, when the operator sets the swtich 62 to the gravimetric mode of operation, the operator then sets the feed rate switch 68 to the desired feed rate R (LBS./HR), which, as discussed hereinbefore, determines the slope of the feed curve or line 70, Fig. 5. The processor then computes the conversion time which may be, for example, T = S (2.5) in seconds, where S is the scale weight as set by switch 66, R
is the desired feed rate set by switch 68, and 2.5 is a constant which, when combined with S/R, produces the conversion time in seconds. The conversion time is the time for each cycle of operation as shown in Figs. 3 and 4, during which manv samples of the input signals are taken and one calculation of feed rate is made. ~ext, the ramp offset 50 is energized which, as pointed out hereinbefore, limits the range of the output 54 of the amplifier 44 to between +5 volts and -5 volts. Initially, it sets said output at about ~5 volts. Next, the processor starts the conversion time. The conversion time T, may, for example, be about 250 milliseconds. A plurality of samples are taken based on the input from the ADC 52, which may for example, be about 100 during each conversion time. The conversion time, T, or time to complete one cycle of operation, is selected to be within the range of from about 1/4 seconds ~09~039 minimum to a maximum of from about 100 to 200 seconds. During this cycle, the output from the amplifier 44 moves from about +5 volts to about -5 volts. Each sample is stored in memory. The samples, generally illustrated in Fig. 5 by dots, form the actual feed curve 114. One of the most important - 20a -~09-~039 operations of the processor is to compute a regression analysis on these samples with respect to time T, and thence compute the RMS error on T.

Fig. 5 illustrates an upper 3 RMS error line at 121 and a lower 3 RMS error line at 123. If less than 20, for example, sample data points exceed 3RMS error in either direction, as indicated at 115 in Fig. 5, regression on T is recomputed with the data points exceeding 3 RMS, as indicated at 117, excluded. Thence, the computed s~ope of the actual feed curve is compared with the slope of the desired or set -point feed line, and a corresponding correction command is outputted at 108 to adjust the motor control 112, thereby to adjust the actual rate of discharge of the material from the feeder assembly 10. This time cycle of operation is continuously repeated to continuously adjust the motor control 112.

If more than 20, for example, sample data points ~xceed 3 RMS error in either direction, as indicated at 119 in Fig. 5, the system is changed into its ACRILOK mode.
r That is, the ACRILOK light 100 is energized and the output command 108 to the DAC 110 and motor control 112 is not updated, but continues in its present state. That is, the processor continues to receive sample signals from the ADC
52 and compute the regression analysis thereof, but no correction command is outputted at 108. The feed rate meter 88 is also locked at the last control data point. The feed system remains in a locked condition until in a subsequent time cycle of op~ration less than 20 data points exceed 3 RMS
error, and then the system is returned to its normal operating ~)9~039 mode and the correction command is again outputted at 108.

As still another operation of the processor, the total feed commanded, as indicated at 84, is compared to the actual total feed, as indicated at 86, periodically, such as every 5 or 10 minutes, for example. If there is a deviation exceeding predetermined limits, the processor modifies the aforementioned command output at 108 to gradually correct the actual feed to the total feed. This is programmed to take from about 5 minutes to about 10 minutes, thereby to avoid sharp fluctuations in the feed rate command, but nevertheless, obtain as close as possible the total feed selected over a long period of time~

A further operation of the processor, is to determine when the scale wei~ht, as indicated by the meter 90, drops to a predetermined low level, as set by the low level s~itch 80, and then search for an "on rate" condition. That is, the output signal outputted at 88 is monitored until the difference between it and the feed rate switch 68 is less than a predetermined error limit. Thence, the system is changed into its refill mode wherein the output command 108 and feed rate meter 88 are not updated, but are retained in its present state, similar to its operation as described hereinbefore in connection with the ACRILOK mode. ~t the same time, a command is outp~tted to a refill circuit 120, which sends a signal to a r~fil]
controller 122 that controls the flow of material from a refill source 124 to the container 12. The controller 122 could ~e an AC motor when handling dry particulate material or could be a valve when handling liquids.

~09~03~

The system remains in the refill mode until the processor detects that the container 12 is refilled, as indicated by the scale weight meter 90, and as selected by the out of low level switch 82. At this time, the processor outpùts a signal to the refill circuit 120 which, in turn, directs the refill controller 122 to discontinue refilling the container 12. The processor then returns the system to its normal operational mode.

Figs. 9 to 14 are various flow charts of the computer 56. Thus, Fig. 9 is a flow chart showing the wait subroutine, and Fig. 10 is a flow chart of the second interrupt subroutine, w~ich is a display type subroutine. Fig. 11 is a flow chart of the derive subroutine wherein the normal conversion time is calculatedO Figs. 12A, 12B and 12C combine to foxm a flow chart of the main routine of the computer 56. Figs. .
13 an~ 14 are flow charts of the calculate and learn mode subroutines r respectively.

Initial conditions and assumptions are, as follows:
GRAV/VOL. = GRAV.
ON/OFF = OFF
AUTO/MAN./BY-PASS= AUTO
SCALE WEIGHT = 1000. lbs.
FEED R~TE S~.T POINT = 200 LBS./HR.
INTO LO~ LEVEL = 20%
OUT OF LOW LEVEL = 80%
MOTOR SPEED = 50%
ASSUME MAX. FEED RATE OF r~CHINE = 2000 LBS./EIR

REAL TIME CLOCK RATE = 1 KHZ (Clock causes interrupt) 10~4039 Flags set by hardware:
Grav. Flag Run Flag Learn Flag ~By-Pass Flag¦
~Man. Flag 5 Reset total Flag Number of Samples per slope calculation = 256 The time between samples is chosen so that you have covered about 60% of the range of the ramp offset 50 for each slope calculation. The ramp offset is reset for each new slope calculation. Thus, the lower the set point the longer it takes to calculate the slope.

The following is a program with descriptive comme~ts for carrying out the basic operations of the computer 56:

1(~4~3~

*L T/2 *T T/2 END ?
177554 OUT = 177554 177552 DATA = 177552 177554 OFFSET = 177554 177550 SET = 177550 177550 LKS = 177550 040200 ONE~ = 040200 . 040400 TWOF = 040400 040700 SIXF = 040700 i . 0p0004 WAITR = 4 000011 READ = 11 ) DEFINITIONS OF
0P0012 WRITE = 12 ) CONSTANTS, ADDRESSES .
000000 R0=~0 ) AND REGISTERS.
: 000001 Rl = %l 000002 R2 =%2 0000,~3 R3 =%3 ' . 000004 R4 =%4 00O005 R5 =~5 000006 R6 =%6 0~0006 SP =%6 000007 PC =~7 - I 109403~

057452 $ADR=57452 060206 $CMR=60206 063500 ~DVR=63500 061664 $GCO=61664 064146 ~IR=64146 ) LINKS TO FLOATING POINT
064232 $MLI=64232 I MATH PACKAGE (FPMP-WRITTEN
064412 $MLR=64412 ) BY D.E.C.) B64772 $NGR=64772 065146 $POLSH=65146 ) 060264 $RCl=60264 065024 $Rl=65024 057446 $SBR=57446 000174 .=174 1 000174 0S~722 .WORD INT ) SET UP lKHZ. CLOCK INTERRUP' ¦ 000176 000340 .WORD 000340 ) VECTOR
' 050000 =50000 050000 01p767 START: MOV PC, STKST

0500~4 016706 MOV STKST, SP ) -; STACK POINTER I S
r 003636 ~ NOW POINTING
050010 005746 TST (SP) ~ ) TO STKST
050012 013700 MOV ~ #177552,R~
~ 177552 ; 050016 052767 BIS #2, SET ) ;INITI~I,I7.
000002 ) oF~SE~r 127524 ) VO~AGE TO
050024 ~12767 MOV #177777,0FESErL` ) ZERO (I~' ) COMPLEMENT
~ FORM

1 ~9~Q3~

. 177777 127522 );INITIALIZE
050032 005~67 CLR SET ) CONTROL
127512 ) VOLTAGE TO
RQ ~ GE OOl ) ZERO(IN
050036 012767 MOV #177777,OFFSET ) COMPLEMENT
) FORM) : 127510 )INITIALIZE
050044 000004 IOT )TELETYPE
050046 00000~ .WORD 0 )THROUGH
¦ 050050 002 .BYTE 2,0 pIOX (IOX IS

)D.E.C.) : 050051 000 ¦ 050052 000~04 IOT )SETS UP .
' )CONTROL P
050054 050060 .WORD ASK )RETURN
. )ADDRESS, ¦ 050056 003 .BYTE 3,0 t ~5~57 00,~
. 050060 012701 ASK: MOV #TABLEl, Rl; GET ADDRESS OF
: , TABLE OF
QUESTIONS

050064 012767 MOV #9., LOOP; SET UP LOOP FOR
NINE QUESTIONS
,0'00011 : 0~3552 050072 01270~ MOV #MTABLE,R0;~ET A~URE~SS OF
TAr3~' CONTAINING

QUESTIONS

050076012067 MORE: MOV (R0)+,WBUFFER

) PRINT THE
050104000000 WBUFFER: .WORD 0 ) QUESTION
050106012 .BYTE WRITE, 1 ) GET A REPLY
050112050250 .WORD BUFFER
050114011 .BYTE READ,0 0501150~0 05011600004 WAITT: IOT ) WAIT UNTIL
) REPLY IS
050120050116 .WORD WAITT ) GIVEN BY
) OPERATOR AT
050122004 .BYTE WAITR,0 ) TTY.

050124012746 MOV #BUFFER~6,(SP)-; PUT ADDRESS
OF REPLY ON
STACK

050130016746 MOV BUFFER +4,(SP)-; PUT LENGTH
OF REPLY ON
STACK
~00120 050134162716 SUB #2, (SP) 050140005046 CLR (SP)- ) )FREE FORMAT CONVERSION
050142005046 CLR (SP)- ) 050144004767 JSR PC,$RCI; CONVERT REPLY
TO FLOATING POINT 1.

050150012621 MOV (SP)+,(Rl)+) ) STORE REPLY IN
050152012621 MOV (SP)+,(Rl)+) TABLE 1.

10~9~039 050154 0'05367 DEC LOOP
0'~3464 0'50'160 001346 BNE MORE
050162 005046 CLR (SP)--050164 012746 MOV #042722, (SP)- ) PUT FLTING
PT. 1680 ON

RQ@GE 00'2 050170 012701 MOV #TABLE 1+14 ,Rl 050174 014146 MOV (Rl)-, (SP)-050176 014146 MOV (Rl)-, (SP)-- ) CALCULATE
) #SAMPLES/SEC.
050200 014146 MOV (Rl)--, (SP)-050'202 014146 MOV (Rl)-, (SP)- ) 050204 004467 JSR R4, $PoLSH

050210 063500' $DVR
050212 050214 .WORD . ~2 050214 011667 MOV (SP), HOLD8 )STORE #SAMPLES/
~3450 ) SEC
050220 016667 MOV 2 (SP), HOLD9 ) 01a3444 050226 004467 JSR R4, $PoLSH
)DIVIDE SAMPLES/
014714 ~ SEC BY 1680 TO
)GIVE THE # OF
050232 063500 $DVR )INTERRUPTS PER
)SAMPLE
050234 ~65Ç~'24 $ RI
050236 050240 . WORD .+ 2 05024J~ 012667 MOV (SP) +, INTSAM; STORE RESULT .
00343~
050244 000167 JMP INIT; GO TO THE INITIALIZATION
SECTION
0~2126 05025,~ 00~10,~ BUFFER~ 0 10~0~9 050252 000000 0 ) BUFFER FOR
) REPLYS TO
050254 000000 0 ) QUESTIONS
050356 .=.~1~0 050356 050450 MTABLE: TABLE

)POINTERS TO
050366 050544 TABLE5 )THE QUESTIONS

050374 05~630 TABLE8 050450 TABLEl: .=.+50 050450 000014 TABLE: TABLE2-TABLE-6 050452 000~00 050456 015 .BYTE 15,12 050457 ~12 050460 106 .ASCII 'FEED V/S='; VOLTS/SECOND
FEED RATE

05~463 104 050466 ~57 RQ~GE 003 05~467 123 050470 ~75 050472 .EVEN
050472 000006 TABLE2: TABLE3-TABLE2-6 050474 ~0~

109~039 050500124 .ASCII 'TIME~'; SMALL SAMPLE TIME
IN SECONDS

050506 .EVEN
050506000006 TABLE3: TABLE4-TABLE3-6 05051~000~0 050514043 .ASCII '#SAM='; #SAMPLES PER
SMALL SAMPLE TIME
05~515123 05052~075 050522 .EVEN
050522000014 TABLE4: TABLE5-TABLE4-6 05~524000~0 050526000014 TABLE5-TABLE4~6 050530105 .ASCII 'ERR BND V/S='; SMALL
SAMPLE ERROR
BAND IN
VOLT/SECOND

05053~122 05~533040 0505341~2 ~50535116 ~50536104 ~5~537040 ~50540126 las403s ~5~541~57 050544 .EVEN
050544000016 TABLE5: TABLE6-TABLE5-6 050552043 .ASCII '#SM SAM/LARGE='; # OF SMALL
SAMPLES
PER LARGE
SAMPLE
TIME.
~50553123 05~561057 ~50562114 ~505631~1 RQ@GE 004 ~50564122 0505651~7 ~50566105 ~5~567~75 050570 .EVEN
.~5057~000006 TABLE6: TABLE7-TABJ.E6-6 050572000~0 050576105 .ASCII 'ERR K='; OUTPUT ERROR
CONSTANT "K"
THIS IS SYSTEM
GAIN.

10~4039 050601~40 050604 .EVEN
050604000016 TABLE7: TABLE8-TABLE7-6 050612043 .ASCII '#SM SAM B4 SW='; # OF SMALL
SAMPLES
BEFORE
SWITCHING.

~50616123 05~620115 05~621040 ~5~623064 05~624~40 05~626127 ~5~627~75 050630 .EVEN
050630000024 TABLE8: TABLE9-TABLE8-6 05063200~00 0 050636123 .ASCII 'STARTUP ERR BND V/S=' 05064~101 ~094039 050651 ~40 05~652 102 RQ@GE 005 05~654 104 050655 ~40 ~50656 126 ~5~657 ~57 ~5~66~ 123 ~5~661 ~75 ~5~662 .EVEN
~5~662 ~p24 TABLE9: TABLEZ-TABLE9-6 ~5~664 050670 ~43 .ASCII '#SM SAM IN STARTUP=' 05~672 115 ~50673 ~4 05~674 123 ~50676 115 ~50677 ~4 ~5~7~0 111 ~507~1 116 05~7~2 ~40 10~4039 ~507~7124 05~710125 050712~75 050714 .EVEN
050714000 TABLEZ: .BYTE 0 050716 .EVEN
050716000167 LINK: JMP RESET

050722005737 INT: TST @#177552; START OF INTERRUPT
SERVICE.

)IS IT TIME TO
002556 ) SAMPLE?

050734000002 RTl 050736004767 SAMPLE: JSR PC, SAVE
~1366 050742005267 INC SET; START A/D CONVERSION

050746105767 CK: TSTB SET

050754016700 MOV DATA, R0; GET THE A/D OUTPUT

RQ@GE 006 050762016767 MOV INTSA, INTS; RESET #
INTERRUPTS/
S~IPLE.

10~4039 ~2524 00252~
050770 022700 CMP #980.,R0 )IS THE A/D OUT-)PUT GREATER THAN
001724 )9 VOLTS? IF
050774 003750 BLE LINK )YES RESET.
050776 060067 ADD R0,Y+2 )SUM THE Y VALUE
002514 )FOR THE
051002 005567 ADC Y )REGRESSION.

051006 016701 MOV X, Rl )MULTIPLY THE X
002506 )BY THE Y
051012 004767 JSR PC,MULTY

051016 060167 ADD Rl,XY+2 0~2514 051~22 005567 ADC XY )FOR THE
002506 )REGRESSION.

051026 060067 ADD R0,XY
0025~2 051032 005367 DEC X; REDUCE X VALUE BY 1 ~02462 051036 001402 BEQ CALC; IF X=O IT IS TIME TO
CALCULATE THE SLOPE
05i04~ 004767 JSR PC,RESTORE

051044 016767 CALC: MOV N,X; RESET THE X VALUE
0~25~0 051~52 016767 MOV Y,YC
002436 ) STORE THE
0~2464 ) ~Y

051060 016767 MOV Y+2,YC~2 10~4039 051066 016767 MOV XY,XYC

)STORE THE ~X

051074 016767 MOV XY+2,XYC+2 051106 005067 CLR XY~2 )RESET ~XY AND
)~Y FOR NEXT
002424 )SAMPLE PERIOD.

051116 005067 CLR Y~2 051122 016746 MOV Nl+2,(SP)- ) 002426 )PUT # SAMPLES
)ON THE STACK.
RQ@GE 007 051126 015746 MOV Nl,(SP)-051132 01670~ MOV XYC, R0 ~51136 0l670l MOV XYC+2,Rl 002400 )CONVERT ~XY TO
)A FLOATING POINT
051142 004767 JSR PC,DFLOAT )# AND PUT IT ON
)THE STACK.
~062~ ) 051146 004467 JSR R4,$POLSH
~13774 051152 064412 $MLR ) (#SAMPLES) x ) ~XY
051154 051156 .WORD .+2 109A03~

051156 016746 MOV Xl+2,(SP)- ) )PUT ~X ON
002350 )STACK
051162 016746 MOV Xl,(SP)-~02342 051166 016700 MOV YC, R0 ~02352 )CONVERT ~Y TO
051172 016701 MOV YC+2,Rl )FLOATING POINT
)AND PUT IT ON
002350 )THE STACK.
051176 004767 JSR PC,DFLOAT
~00564 051202 004467 JSR R4,$PoLSH
013740 )GET (#SAMPLES) ) (~XY)-~X~Y
~51206 064412 $MLR
051210 057446 $SBR
051212 051214 .WORD .+2 051214 016746 MOV Nl+2,(SP)-)PUT # SAMPLES
002334 )ON THE STACK.
051220 016746 MOV Nl,(SP)-051224 016746 MOV X2~2,(SP)- ) 2 )PUT ~X ON
002276 )STACK.
051230 016746 MOV X2,(SP)-0~2270 051234 004467 JSR R4,$PoLSE
)GET (#SAMPLES) 013706 ) (~x2) 051240 064412 $MLR
~51242 051244 .WORD .+2 051244 016746 MOV X1~2,(SP)-002262 )PUT ~X ON
)STACK
051250 016746 MOV Xl,(SP)- ) 109~039 ~2254 051254 016746 MOV X1~2,(SP)- ; ~X ON STACK AGAIN

051260 016746 MOV Xl,(SP)-051264 004467 JSR R4,$PoLSH ) 051270 064412 $MLR
)(#SAMPLES) RQ@GE 010 ) (~XY)-(~X)(~Y)-)(#SAMPLES) 051272 057446 $SBR ) (~X2)-(~X)(~Y) 051274 063500 $DVR ) SLOPE
051276 064772 $NGR
051300 051302 .WORD .+2 051302 016746 MOV SAMS01t2,(SP)-) )PUT # SAMPLES/
002252 )SECOND ON
)STACK
051306 016746 MOV SAMS01,(SP)-051312 004467 JSR R4,$POLSH
01363~
051316 064412 $MLR
051320 051322 .WORD .t2 051322 005046 CLR (SP)-051324 012746 MOV #041710,(SP)-;FLOATING POINT

051330 004467 JSR R4,$PoLSH
~13612 051334 063500 $DVR ; VOLT - SLOPExSAMPLE x SEC SEC lOO
051336 051340 .WORD .~2 051340 011667 MOV (SP),TEMP
)STORE V/S FOR
002216 )LATER USE.

051344 016667 MOV 2(SP),TEMP~2 9 4~ 3 9 ~000~2 0~2212 051352 016746 MOV PREV+2,(SP)- ) )PUT PREVIOUS
002212 )V/S ON STACK
051356 016746 MOV PREV,(SP)-051362 004467 JSR R4,$POLSH
013560 )PREV-CURRENT
)v/s .
051366 057446 $SBR
05137~ 051372 .WORD .+2 051372 032716 BIT #1000~0,(SP) 1~0000 ~51376 001404 BEQ OVR )GET THE
)A,BSOLUTE VALUE
051400 004467 JSR R4, $POLSH )¦PREV V/S-) CURRENT V/S¦

051404 064772 $NGR
051406 05141~ .WORD .+2 051410 005767 OVR: TST ERRSW
)LARGE OR SMALL
002156 )ERROR BAND?

~51416 ~ 5367 DEC ERRSW-SMALL--DECREASE # SMALL
SAMPLES BEFORE
SWITCHING ERROR
BANDS.

051424 016746 MOV SEI2,(SP)-)MOVE SMALL
002150 )ERROR BAND
)ONTO STACX.
051430 ~16746 MOV SE,(SP)- ) 051434 000404 BR TSTE; TEST FOR ACRILOK
RQ@GE 011 ~51436 ~16746 LARGE: MOV LE+2,(SP)- ) )MOVE LARGE
~2142 )ERROR BAND
)ONTO STACK.
051442 ~16746 MOV LE,(SP)-~2134 051446 004467 TSTE: JSR R4,$PoLSH
013474 ) COMPARE
) PREV V/S-051452 ~6~2~6 $CMR ) CURRENT V/S
) TO ALLOWABLE
051454 051456 .WORD .12 ) ERROR IN V/S
) AND JMP IF TOO
051456 ~03402 BLE .+6 ) LARGE.

051464 016767 MOV TEMP,PREV; )THIS IS .+6 002~72 )YOU ARE WITHIN
)THE ERROR BAND
002074 )(STORE THE FEED
)RATE IN V/S) 051472 016767 MOV TEMP+2,PREV+2) ~02070 051500 005267 INC UPDAT;SET THE FLAG TO INDICATE
A NEW FEED RATE HAS JUST
BEEN CALCULATED

)ARE WE USING
002102 )LARGE OR SMALL
)SAMPLES?

051512 005367 DEC LOS:DECREMENT # OF SMALL SAP~PLES

~51516 016746 UPDATE: MOV K+2,tSP)-)PUT OUTPUT
002076 )CONSTANT
)(SYSTEM GAIN) 051522 016746 MOV K, (SP)- )ON THE STACK.
~2~70 051526 ~16746 MOV FR +2,(SP)- ) )PUT DESIRED
002072 )FEED RATE ON
)THE STACK.
~51532 ~16746 MOV FR,~SP)-~09A039 ~2064 051536 016746 MOV PREV+2,(SP)- ) )PUT CURRENT
002026 )FEED RATE ON
)THE STACK.
051542 016746 MOV PREV,(SP)-002~2~
051546 004467 JSR R4,$PoLSH
~13374 051552 057446 $SBR )(CURRENT-DESIRED) )K ~ CONWOR
051554 064412 $SMLR )PREVIOUS MOTOR
)SPEED.
051556 065024 $RI
051560 051562 .WORD .+2 051562 062667 ADD (SP)~,CONWOR ) 051566 026727 CMP CONWOR,#2000 )IF RESULT IS
002000 )GREATER THAN
)2000 (6V@
051574 100403 BMI CNTU )OUTPUT OF D/A) )MAKE IT=2000;
051576 012767 MOV#1777,CONWOR )I.E., LIMIT
)RESULT TO 6 VOLTS

0~2022 RQ@GE 012 051604 042767 CNTU:BIC#02,SET; GET SET TO UPDATE MOTOR
SPEED.

)THE D/A USES
002010 )NEGATIVE LOGIC.
051616 016767 MOV CONWOR,OUT

0020~4 051624 005167 COM CONWOR; BUT THE PROGRAMMER
PREFERS TO THINK
POSITIVE.

10~4039 ~01776 051630 004767 JSR PC,RESTORE;GO BACK TO WHERE
YOU WERE BEFORE
BEING RUDELY
INTERRUPTED.

051634 016746 LAR: MOV PREV~2,(SP)- ) 0~1730 }
051640 016746 MOV PREV,(SP)- )IF YOU ARE
)CALLING FOR
001722 )LARGE SAMPLES, )I.E. AN AVERAGE
051644 016746 MOV AVG~2, (SP)- )OF THE V/S
)CALCULATIONS, 001762 )THEN YOU ARE
)HERE. COMPUTE
051650 016746 MOV AVG, (SP)- )THE RUNNING
)AVERAGE.
0~1754 051654 004467 JSR R4,$PoLSH }

051660 057452 $ADR
051662 051664 .WORD .+2 )IF YOU HAVE
051670 001411 BEQ CALL )ENOUGH V/S
)CALCULATIONS
051672 005367 DEC SSLST )USE THE
)AVERAGE;I.E.
001736 )JUMP TO CALL.
) 051700 012667 MOV (SP)+,AVG.
0~1724 )YOU DON'T HAVE
)ENOUGH V/S
051704 012667 MOV ~SP)+,AVG+2 )CALCULATIONS.
)RETURN TO WHERE
001722 )YOU ~ERE BEFORE
)THE INTERRUPT.
~51710 004767 JSR PC,RESTORE
0~0442 051714 016767 CALL: MOV SSLSTI,SSLST ) ~1716 ` 1094039 001712 )RESET #SMALL
)SAMPLES PER
051722 016746 MOV SSLSTR+2,(SP)- )LARGE SAMPLE
)TIME.

051726 016746 MOV SSLSTR,(SP)-;PUT #SMALL
SAMPLES/LARGE SAM.
ON STACK.

051732 004467 JSR R4,$PoLSH
013210 )GET THE AVER.
)OF THE SMALL
051736 063500 $DVR )SAMPLES COM-)PRISING THE
051740 051742 .WORD .~2 )LARGE SAMPLE.
051742 012667 MOV (SP)+,PREV
001620 )STORE THE
)AVERAGE.
051746 012667 MOV (SP)+,PREV+2 RQ@GE 013 001652 )RESET THE AVG.
051756 005067 CLR AVG+2 051762 00~167 JMP UPDATE;REFRESH THE MOTOR
SPEED.

051766 ~12667 DFLOAT: MOV (SP)+,RTRN

051772 005046 CLR (SP)-051774 005046 CLR -(SP) 052004 005701 TST Rl 052012 005401 OVE27: NEG Rl 052016 005601 SBC Rl 052020 006l46 POS27: ROL -(SP) ~52022 000241 CLC
052024 012702 MOV #240,R2 052030 006101 NOM 27: ROL Rl 052034 103402 BCS NOD27 )DOUBLE
052036 005302 DEC R2 )PRECISION
052040 000773 BR NOM27 )INTEGER TO
052042 000301 NOD27: SWAB Rl )FLOATING POINT
052044 110166 MOVB Rl,4(SP) )SUBROUTINE
00~004 052050 110066 MOVB R0,5(SP) 052056 150200 BISB R2,R0 052062 006026 ROR (SP)~ ) 052066 006066 ROR 2(SP) 000~02 052072 010016 MOV R0,@SP
052074 000137 ZER27: JMP @(PC)+
052~76 000000 RTRN: 0 052100 005002 MULTY: CLR R2 )INTEGER MULTIPLY
052102 005004 CLR R4 )SUBROUTINE
052104 012703 MOV #16.,R3 )16BIT X 16BIT=
000020 )32 BIT RESULT.

10~4(~.~9 052112 103001 MR: BCC .~4 052114 060102 ADD Rl,R2 RQ@GE 014 052116 006~02 ROR R2 )INTEGER
) 052120 006000 ROR R0 )MULTIPLY
052122 005303 DEC R3 ¦SUBROUTINE
052124 001372 BNE MR )16BITx16BIT=
052126 010001 MOV R0,R1 ¦32BIT RESULT.
052130 010200 MOV R2,R0 )(CONT'D.) 052134 052767 RESET:BIS#2,SET
)WHEN A/D OUTPUT

)RAMPS GREATER

)THAN 9V LIMIT
052142 062767 ADD#17,0FFDAC
)RESET IT CLOSE
0~0017 )TO ZERO BY
0~0136 )CHANGING THE
052150 016767 MOV OFFDAC,OFFSET
)OFFSET VALUE &

)COMPARING

)LOOPING. NOTE
052156 012767 MOV#24150,LOOPl;90MILLISEC
)THE RESPONSE

)TIME OF 9O
0~0124 )MILLISEC FOR
052164 ~05367 A:DEC LOOPl )LARGE STEPS, &

)WHEN YOU GET

)CLOSE TO ZERO, 052172 062767 RESETA:ADD#l,OFFDAC
)RESPONSE TIME
0~0~01 )OF 5 MILLI-0001~6 )SECONDS.
052200 016767 MOV OFFDAC,OFFSET
~01~2 ) 1~9403~

052206 012767 MOV#4440,LOOPl; 5MILLISEC
004440 )WHEN A/D OUT-000~74 )PUT RAMPS
052214 005367 B:DEC LOOPl )GREATER THAN 9V
000070 )LIMIT RESET IT
052220 001375 BNE B )CLOSE TO ZERO
052222 005267 INC SET )BY CHANGING THE
125322 )OFFSET VALUE &
052226 105767 WATHO:TSTB SET )COMPARING, 125316 )LOOPING.NOTE THE
p52232 10~375 BPL WATHO )RESPONSE TIME
~52234 026727 CMP DATA,#177631 )OF 9OMILLISEC
125312 )FOR LRG STEPS &
177631 ~WHEN YOU GET
~52242 100~01 BPL CONTIN )CLOSE TO ZERO, ~52244 000752 BR RESETA )RESPONSE TIME
052246 016767 CONTIN:MOV N,X )OF 5 MILLISEC-~1276 )ONDS.
0~1244 052254 016767 MOV INTSA,INTS; RESET # INTER-RUPTS/SAMPLE

RQ@GE 015 ~52262 ~5~67 CLR Y
~1226 )ZERO THE SUMS;
~52266 ~5~67 CLR Y+2 )THROW OUT THIS
~1224 )SAMPLE PERIOD
052272 005067 CLR XY )DUE TO THE
0~1236 )NEED FOR RE-052276 005067 CLR XY+2 )SETTING.

~0940~9 ~1234 052302 004767 JSR PC,RESTORE;RETURN TO PREVIOUS
TASK.

052306 000000 OFFDAC:0 052310 000000 LOOPl:0 052312 000000 HPREMP:HALT;IF HOPPER IS EMPTY HALT.
052314 005267 ACRILOCK: INC ACRILK

052320 005267 INC UPDAT )SET ACRILOCK
001162 )FLAG.
052324 004767 JSR PC,RESTORE

052330 012667 SAVE: MOV (SP)+, SAV

052334 010046 MOV R0,(SP)- ) 052336 010146 MOV Rl,(SP)- 3 052340 010246 MOV R2,(SP)- )SAVE SUBROUTINE
052342 010346 MOV R3,(SP)-052344 010446 MOV R4,(SP)-~52346 ~1~546 MOV R5,(SP)- 3 ~52350 000137 JMP @(PC)+
052352 00~00 SAV: 0 3 052354 000000 SAVl: 0 052356 0~5726 RESTORE: TST ( SP ) +
052360 012605 MOV (SP3+,R5 052362 0126~4 MOV (SP)+,R4 ~52364 012603 MOV (SP)+,R3 )RESTORE
~52366 ~12602 MOV (SP)+,R2 )SUBROUTINE.
~5237~ ~126~1 MOV (SP)+,Rl 10940~9 ~52372 ~126~ MOV (SP)+,R~ )RESTORE
)SUBROUTINE
~52374 ~ 2 RTI
~52376 ~16746 INIT: MOV TABLEl+12,(SP)-;# SAMPLES
) YOU COME HERE
176~1~ ) AFTER ANSWERING
) QUESTIONS TO
~524~2 ~16746 MOV TABLEl~l~,(SP)- ESTABLISH A
NEW SET OF
176~2 OPERATING
PARAMETERS.
~524~6 ~4467 JSR R4,$POLSH
~12534 ~52412 ~65~24 $RI
~52414 ~52416 .WORD .+2 052416 012667 MOV (SP)+,HOLD; INTEGER # SAMPLES.
~1226 ~52422 ~16746 MOV TABLE1~12,(SP)-) RQ@GE 016 052426 016746 MOV TABLEl+10,(SP)-) 052432 016746 MOV TABLEl+12,(SP)-) 175754 )CALCULATE NEW
052436 016746 MOV TABLEl+10,(SP)-) ~X =
175746 )x(x+l) Z
052442 005046 CLR (SP)-052444 012746 MOV #ONEF,(SP)-052450 004467 JSR R4,$PoLSH
~12472 ~52454 057452 $ADR
052456 064412 $MLR

052460 052462 .WORD .+2 ~52462 005046 CLR (SP)-1~94039 052464 012746 MOV #TWOF,(SP)- ) 052470 004467 JSR R4, $PoLSH
012452 )CALCULATE NEW
052474 06350~ $DVR ) ~X -052476 ~525~ .WORD .+2 ) x (x+l) ~525~ ~12667 MOV (SP)+,HOLDl ~1146 )PUT IT IN
)STORAGE
~52504 ~12667 MQV (SP)+,HOLD2 ~1144 ~5251~ ~5~46 CLR (SP)-~52512 ~12746 MOV #ONEF,(SP)- ) ~402~ 1 ~52516 ~16746MOV TABLEl+12,(SP)-) 17567~ ) 052522 ~16746MOV TABLEl+10,(SP) ) 052526 005046 CLR (SP)- )CALCULATE NEW
~5253~ ~12746 MOV #TWOF,(SP)- ) ~X
~404~ )(2x+1)(x+1)(x) ) 6 ~52534 ~4467 JSR R4,$POLSH
~124~6 ~5254~ ~64412 $MLR
~52542 ~57452 $ADR
~52544 ~52546 .WORD .+2 ~52546 ~16746MOV TABLEl+12,(SP)-) 17564~ ) ~52552 016746MOV TABLEl~l~,(SP)-) ~52556 ~16746MOV TABLEl+12,(SP)-) 1756~

1~40.'39 052562 016746 MOV TABLEl110,(SP)-) ~52566 005046 CLR (SP)-052570 012746 MOV #ONEF,(SP)- ) 0402~ ) RQ@GE 017 052574 004467 JSR R4,$POLSH

~52600 057452 $ADR
052602 ~64412 $MLR
052604 ~64412 $MLR )CALCULATE NEW
~52606 ~52610 .WORD .+2 ¦ ~X2 _ ~5261~ 0~5~46 CLR (SP)- )(2x+1)(xll)(x) ) 6 ~52612 012746 MOV #SIXF,(SP)-~4070~ ) ~52616 ~04467 JSR R4,$PoLSH
~12324 ~52622 0635~ $DVR
052624 052626 .WORD .+2 052626 012667 MOV (SP)+,HOLD3 ) PUT IT IN
001024 ) STORAGE
052632 012667 MOV (SP)+,HOLD4 001~22 ~52636 ~16746MOV TABLEl+42,(SP)-) 1756~ ) ~52642 ~16746MOV TABLEl+40,(SP)-) )CONVERT NEW
175572)# SMALL
)SAMPLES BEFORE
052646 004467 JSR R4, $PoLSH )SWITCHING ERROR
)BANDS & CONVERT

012274 )TO INTEGER
052652 ~65024 $RI
052654 052656 .WORD .+2 1~3940:~9 052656 012667 MOV (SP)+,HOLD5;PUT IT IN STORAGE

052662016746 MOV TABLEl+22,(SP)-) 052666016746 MOV TABLEl+20,(SP)-)CONVERT NEW
)#SMALL
175526 )SAMPLES PER
)LARGE SAMPLE
052672004467 JSR R4,$PoLSH )& CONVERT TO
)INTEGER.

052676065024 $RI
052700052702 .WORD .~2 052702012667 MOV (SP)+,HOLD6; PUT IT IN
STORAGE

052706016746 MOV TABLEl+32,(SP)-) 052712~16746 MOV TABLEl+30,(SP)-) )CONVERT NEW #
175512 )SMALL SAMPLES
)BEFORE SWITCH-~52716004467 JSR R4,$POLSH )ING TO LARGE
)SAMPLES &
012224 )CONVERT TO
)INTEGER.
052722065024 $RI
052724052726 .WORD .+2 052726012667 MOV (SP)+,HOLD7; PUT IT IN
STORAGE
0~734 052732005067 CLR LKS;TURN OFF THE REAL TIME
CLOCK

RQ@GE 020 )ZERO THE SUMS.
052742005067 CLR XY+2 0~0570 ~52746 0~5~67 CLR Y
000542 )ZERO THE SUMS.
052752 005067 CLR Y+2 052756 016767 MOV HOLD8,SAMS01 052764 016767 MOV HOLD9,SAMS01+2 ) 052772 016767 MOV HOLD7,LOS
~00670 053000 016767 MOV HOLD6,SSLST
00066~ ) 053006 016767 MOV HOLD5,ERRSW
0~0650 00~556 053014 016767 MOV HOLD4,X2+2 )MOVE THE NEW
000640 )PARAMETERS INTO
)REAL TIME
000504 )VARIABLES
)DVRING THE TIME
053022 016767 MOV HOLD3,X2 )WHEN THE CLOCK
)IS OFF SO THAT
000630 )THE TRANSITION
)DOES NOT OCCUR
000474 )IN THE MIDDLE
)OF A SAMPLE
053030 016767 MOV HOLD2,Xl+2 )PERIOD.
00~20 0~474 053036 016767 MOV HOLDl,Xl ~00610 ~464 053044 016767 MOV HOLD,N

~00476 053052 016767 MOV SSLST,SSLSTI
0~556 ~00556 053~6P 016767 MOV N X
~0464 ~0432 053066 016767 MOV TABLE1,FR
1753~6 000526 )MOVE THE NEW
053074 016767 MOV TABLE1~2,FR+2 )PARAMETERS INTO
175302 }REAL TIME
~00522 )VARIABLES
0531~2 016767 MOV TABLE1+10,N1 ¦DURING THE
175302 )TIME WHEN THE
000442 )CLOCX IS OFF
RQ@GE ~21 ¦SO THAT THE
05311~ ~16767 MOV TABLE1+12,N1+2 )TRANSITION
175276 )DOES NOT OCCUR
0~436 )IN THE MIDDLE
~53116 ~16767 MOV TABLE1+14~SE }OF A SAI-IPLE
175272 )PERIOD
00~452 053124 016767 MOV TABLE1+16,SE+2 ) ~0~446 ~53132 ~16767 MOV TABLE1+34 LE

0~442 }
~5314~ ~16767 MOV TABLE1+36LE+2 ~94`039 000436 )MOVE THE
053146 016767 MOV TABLE1+24,K )NEW PARA-175252 )METERS INTO
000442 )REAL TIME
053154 016767 MOV TABLE1+26,K+2 )VARIABLES
175246 )DURING THE
000436 )TIME WHEN THE
053162 016767 MOV INTSAM,INTSA ¦CLOCK IS OFF
000506 )SO THAT THE
000322 )TRANSITION
053170 016767 MOV INTSA,INTS )DOES NOT OCCUR
000316 )IN THE
000312 )MIDDLE OF A
053176 016767 MOV TABLE1~20SSLSTR)SAMPLE
175216 )PERIOD

053204 016767 MOV TABLE1+22SSLSTR+2) 000412 )ZERO AVG
053216 005067 CLR AVG~2 053222 016706 MOV STKST,SP
000420 )RESET THE
)STACK
053226 005746 TST (SP)- ) 053230 052767 BIS ~40,LKS;TURN ON THE REAL TIME
CLOCK
00~040 053236 005767 TEST: TST UPDAT;HAS A NEW FEEDRATE
BEEN CALCULATED?

053242 001003 BNE NEWDAT;YES PRINT IT
053244 000001 WAIT;NO-WAIT FOR INTERRUPT.
053246 000167 JMP TEST;RETURN HERE FROM
INTERRUPT.

053252 005267 NEWDAT: INC CR
0~160 RQ@GE 022 053264 016767 MOV TEMP,TEM
00~272 ~53272 016767 MOV TEMP~2,TEM+2 000266 )PRINT OUT
000204 )NEW FEED RATE
053300 000406 BR ABC )ON TTY;
053302 016767 AB: MOV PREV,TEM )5 PRINTOUTS
000260 )PER LINE, 000172 )WITH * IF IN
053310 016767 MOV PREV~2,TEM+2 )ACRILOK

053316 005~67 ABC: CLR UPDAT
00~164 ~53322 012746 MOV #BUFF,~SP)- 3 053326 012746 MOV #14.,(SP)- ) ~53332012746 MOV #5,(SP)- ) ~ 5 053336~5~46 CLR (SP)- }
~5334~~16746 MOV TEM+2,(SP)-~14~ ) ~53344~16746 MOV TEM,(SP)-~132 ~53350~4767 JSR PC,$GCO

053362012767 MOV #'*,BUFF
) PRINT OUT

) NEW FEED
0~0~66 ) RATE ON TTY;

) 5 PRINTOUTS
00~212 ) PER LINE, WITH
053374022767 AC: CMP #5,CR
) * IF IN
0~00~5 ) ACRILOK.
00~34 ~0~26 05341~000004 lOT
053412053440 .WORD CRLF
~53414012 .BYTE WRITE,l 05341600~004 OUT': lOT
RQ@GE ~23 053420053450 .WORD BBUFF

iO94~.~9 053422012 .BYTE WRITE,l )PRINT OUT NEW

)FEED RATE ON
053424000004 WAIT: IOT
)TTY; 5 PRINT-053426053424 .WORD WAIT
)OUTS PER LINE, 053430004 .BYTE WAITR,l )WITH * IF IN
~53431001 )ACRILOK.

~534360000~0 CR:0 053440000002 CRLF: 2 053444000~2 2 053446015 .BYTE 15,12 05345000~016 BBUFF: 14.
053452000~00 0 0534540~0016 14.
053502 BUFF: .-.120.
053506 TEM: .=.+4 053506000000 UPDAT: 0 053510000000 INTS: 0 )LOCATIONS
053512000000 INTSA: 0 )FOR VARIABLES
053514000000 Y: 0r0 )FLAGS, &
053516000000 )BUFFERS
~53520~00000 X: 0~0 053522~00000 053524000~0~ ~2: 0 ~53526000000 05353~0~000 Xl~ 3 0535320~0~00 ~53534000000 XY: 0,0 1~40.~

0535360000~0 053540000000 XYC: 0,0 053544000000 YC: 0,0 053550000000 N: 0 053552000000 Nl: 0,0 053556000000 SAMS01: 0,0 053562000000 TEMP: 0~0 )LOCATIONS
053564000000 )FOR
053566000000 PREV: 0,0 ¦VARIABLES~
053570000000 )FLAGS, 053572000000 ERRSW: 0,0 )AND
053574000000 )BUFFERS
053576000000 SE: 0~0 053600000~00 RQ@GE 024 053602000000 LE: 0~0 0536~4~00~00 053606000000 ACRILK: 0,0 0536100~000~ ) 053612000000 LOS: 0,0 0536140000~0 053616000000 K: 0,0 053620~0~00 053622000000 FR: 0,0 ~53624~ 00 053626000000 CONWOR: 0 053630000000 AVG: 0,0 ! 11~40~9 ~53632 000000 053634 000000 SSLST: 0 053636 000000 SSLSTl: 0 053640 000000 SSLSTR: 0,0 053644 000000 LOOP: 0 053646 000000 STKST: 0 ) LOCATIONS
053650 000000 HOLD: ) ) FOR
053652 000000 HOLDl: 0 ) VARIABLES, 053654 000000 HOLD2: 0 ) FLAGS, 053656 000000 HOLD3: 0 ) AND
053660 000000 HoLD4: 0 ) BUFFERS
053662 000000 HOLD5: 0 053664 000000 HoLD6: 0 053666 000000 HOLD~: 0 053670 000000 HoLD8: 0 ) 053672 000000 HOLD9: 0 053674 000000 INTSA~I: 0 000001 .I~`ND
RQ@GE 025 ~0~41).~

SYMBOL TABLE LISTING

A052164 AB 0533~2 ABC 053316 AC 053374 DATA= 177552 DFLOAT 051766 ERRSW 053572 FR 053622 HOLD053650 HOLDl053652 HOLD2053654 HOLD3 053656 LINK050716 LKS= 177550 LOOP053644 LOOPl 052310 NOM27052030 Nl053552 OFFDAC ~52306 OFFSET= 177554 ONEF= 040200 OUT177554 OUTl053416 OVER27 052012 OVR051410 PC=~000007 POS27052020 PREV 053566 READ= 000011 RESET052134 RESETA 052172 RESTOR 052356 RTRN052076 R0=%000000 Rl =%000001 R2 =%000002 R3=~000003 R4=%000004 R5 =%000005 R6 _%000006 SAVl052354 SE053576 SET = 177550 SIXF = 040700 SP=%000006 SSLST053634 SSLSTR 0536~0 SSLSTl 053636 START050000 ST~ST053646 TABLE050450 TABLEZ 050714 TABLEl 050400 TABLE2 050472 TABLE3 050506 TABLE4 050522 TABLE5 050544 TABLE6 050570 TABLE7 0506,~4 TABLE8 050630 TSTE051446 TWOF = 040400 UPDAT 053506 UPDATE 051516 WAIT053424 WAITR = 000004WAITT 050116 WATHO 052226 W~UFFE 050104 WRITE - 000012 X053520 XY 053534 XYC~53540 Xl053530 X2053524 y053514 YC053544 ~ER27052074 $ADR= 057452 $CMR= 060206 $DVR= 063500 $&CO= 061664 $IR= 064146 $MLI= 064232 $MLR= 064412 $NGR= 064772 $PoLSH =065146 $RCI- 060264 $RI= 065024 $SBR= 057446 . = 053676 *S

10940~9 From the foregoing disclosure, it can be seen that the instant invention provides an improved weigh feeding apparatus, wherein the discharge rate of a substance from a container may be maintained at a preselected constant value, wherein the container may be automatically refilled during the continuous discharge of the substance, wherein excessive excursions of the system are eliminated, wherein extraneous data recordings are eliminated when calculating the flow rate, and wherein past flow rate values may be stored in memory and compensated for at a later point in time.

Although a certain particular embodiment of the invention has been herein disclosed for purposes of explanation, ~arious modifications thereof, after study of the specification, will be apparent to those skilled in the art to which the ~nvention pertains. .

WHAT IS CLAIMED AND DESIRED TO B~ SECURED BY
LETTERS PATENT IS:

-, ,

Claims (16)

The embodiments of the invention in which an exclu-sive property or privilege is claimed are defined as follows:

1. A weigh feeding machine comprising:
- a container for a substance;
- means for discharging substance from the container at a controllable feed-out rate;
- means for sensing the weight of at least the container and any substance therein and for producing a first electrical signal indicative of the instantaneous value of said weight;
- a digital microprocessor and a digital memory;
- means for supplying to said digital microprocessor and memory said first electrical signal and a second electrical signal indicative of a desired feed-out rate;
- means for causing said digital microprocessor and memory to combine said first and second electrical signals and to produce as a result a third electrical signal indicative of the degree of a departure, if any, from the desired feed-out rate;
- means for causing the discharging means to feed out said substance at a feed-out rate determined by said third electrical signal;
- means for detecting forces which act on said weight sensing means and are in addition to the forces acting thereon which are due to the weight of said container and substance, and for producing a fourth electrical signal indicative of said additional forces; and - means for supplying said fourth electrical signal to the digital microprocessor and memory and for causing the digital microprocessor and memory to compensate said third electrical signal for the additional forces of which said fourth electrical signal is indicative and to thereby tend to make the feed-out rate insensitive to said additional forces.

2. A weigh feeding machine as in Claim 1 which includes means for monitoring the first electrical signal and for producing a fifth electrical signal when a selected characteristic of the first electrical signal is outside a defined range, and means for causing the digital micro-processor and memory to respond to said fifth electrical signal by inhibiting the operation of the third electrical signal, to thereby maintain the feed-out rate at the level thereof existing immediately before said fifth electrical signal.

3. A weigh feeding machine as in Claim 2, including means for supplying said digital microprocessor and memory with a sixth electrical signal indicative of a desired minimum feed-out rate, means for causing the digital microprocessor and memory to produce an under-feed alarm signal when the feed-out rate indicated by changes in said first electrical signal falls below the minimum feed-out rate indicated by said sixth signal and means for displaying said under-feed alarm signal.

4. A weigh feeding machine as in Claim 2, including means for supplying to said digital microprocessor and memory a seventh electrical signal indicative of a maximum desired feed-out rate, means for causing the digital microprocessor and memory to produce an over-feed alarm signal when the actual feed-out rate indicated by changes in said first electrical signal exceeds the over-feed rate indicated by said seventh signal and means for displaying said over-feed alarm signal.

5. A weigh feeding machine as in Claim 4, which includes means for producing a refill electrical signal when the weight sensed by the sensing means falls below a selected minimum weight, means for causing an automatic refill of the container with substance to a desired weight level in response to said refill signal and means for causing the digital micro-processor and memory to inhibit the operation of said third electrical signal, to thereby maintain the feed-out rate at the level existing immediately prior to the refill signal at least for the duration of said automatic refill.

6. A weigh feeding machine as in Claim 5, which includes means for producing an over-weight electrical signal when the weight sensed by the sensing means represents a feed-out rate which exceeds a selected maximum feed-out rate and means for causing the digital microprocessor and memory to respond to said over-weight signal by inhibiting the operation of the third electrical signal, to thereby maintain the feed-out rate at the level thereof existing immediately before the over-weight signal.

7. A weigh feeding machine as in Claim 1, wherein said means for supplying to said digital microprocessor and memory said first electrical signal includes amplifier means for amplifying said first electrical signal, an analog-digital converter coupled between said amplifier means and said digital microprocessor, digital-analog converter ramp offset means controlled by said digital microprocessor and having a controlled staircase-like stepping output applied as an addi-tional input signal to said amplifier means to algebraically combine with said first electrical signal, each step corre-sponding to one of a series of periods of time thereby to maintain the output of said amplifier in a given preselected range of amplitude during each of said periods of time.

8. A weigh feeding machine as in claim 1 wherein said digital microprocessor and memory is adapted to store in memory a series of said first signals for each period of a series of periods of time to maintain said third signal constant during the time when a preselected number of said first signals exceeds preselected upper or lower limits, during one of said periods of time.

9. A weigh feeding machine as in claim 1 wherein said digital microprocessor and memory is adapted to store in memory a series of said first signals for each period of a series of periods of time, and to compute said third signal disregarding a preselected number of said signals exceeding preselected upper or lower limits, during one of said periods of time.

10. A weigh feeding machine as in claim 9 further com-prising means for correcting said first electrical signal to compensate for errors due to noise components due to moving machinery on the scale such as the motor, gear box, augers, as well as movement of the material in the container.

11. A weigh feeding machine as in claim 10 wherein said means for correcting said first electrical signal includes encoder means coupled between said means for discharging substance from the container and said digital microprocessor.

12. A weigh feeding machine as in claim 1 wherein said means for supplying to said digital microprocessor and memory said first electrical signal includes first amplifier means for amplifing said first electrical signal, a first analog-digital converter coupled between said first amplifier means and said digital microprocessor, second amplifier means for amplifying the signal received from said first amplifier means, a second analog-digital converter coupled between said second amplifier and said digital microprocessor.

13. A weigh feeding machine as in claim 12, wherein said digital microprocessor and memory is adapted to integrate said second signal indicative of a desired feed-out rate with respect to time and output a display corresponding to the desired total feed commanded, and said digital microprocessor and memory being further adapted to integrate the signals received from said first analog-digital converter indicative of the actual total weight of material fed with respect to time and, by comparing said total feed command to said actual total weight of material fed, adjust said third signal.

14. A weigh feeding machine as in claim 12 wherein said first amplifier means has a range of between -10 volts when the container is full to +10 volts when the container is empty.

15. A weigh feeding machine as in claim 12 wherein said second amplifier means has a range between +5 volts and -5 volts during each period of a series of periods of time.

16. A weigh feeding machine as in claim 1, wherein said means for discharging substance from the container includes a motor driven feeder assembly, means for inputting into said digital microprocessor and memory a fifth signal indicative of the actual speed of said motor, means for inputting into said digital microprocessor and memory a sixth signal indicative of the desired rotational speed of said motor, means for causing said digital microprocessor and memory to combine said fifth and sixth signals and to produce a seventh signal indicative of the degree of the departure, if any, from the desired motor speed, and means for causing the motor to operate at a speed determined by said seventh signal.