US3643076A
Expired / Lapsed
US
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Process controller
Assignee: NAT RES DEV
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Filing: 1969-09-03
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Granted: 1972-02-15
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Expires: 1989-09-03
Abstract
Abstract A control system is described which has a number of control loops with individual sensing and actuating stages but a common arithmetical unit for calculating digital error and error rate signals. A common set point store is also provided for providing reference information for the arithmetical unit. Such a control system is useful where there are too few control loops to warrant the use of a computer. Actuator drive apparatus is also described for providing a drive signal for the actuators in the loops. The apparatus receives the error signal and the error rate signal from the arithmetical unit, and multiplies these signals by constants by counting down registers containing the signals at preselected rates. If the signals have the same sign the registers are counted down one after the other and the actuator is energized for the duration of countdown, but if the signals are of different sign the registers are counted down concurrently until one reaches zero, and then the actuator is energized while the other register completes countdown.
Inventors
- 👤 Charles Anthony Bell
- 👤 Anthony David Young
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 19:38
CPC Classifications
G; G05; G05B; G05B15/00; G05B15/02; G05D; G05D23/00; G05D23/19; G05D23/1917; G05D7/00; G05D7/06
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
155 words
Actuator-drive apparatus for providing a signal to drive a reversible actuator in dependence upon groups of digital input signals, including a number of numerical storage means, one storage means for, and associated with, each of a number of digital input signals in a group of such signals, and each storage means being adapted to store a number and a sign representing the associated signal in each group, countdown, means for counting the numbers stored by the storage means down to zero at selectable predetermined rates, individual to each storage means, and control means for forming the sum of the times taken to count down the numbers stored by the storage means, taking account, in forming the said sum, of the signs of the numbers counted down, the control means also being adapted to provide a drive signal for an actuator for a time, and in a direction, determined by the sum and its sign, respectively.
Claim 2
Dependent Claim
155 words
Actuator-drive apparatus for providing a signal to drive a reversible actuator in dependence upon groups of digital input signals, including a number of numerical storage means, one storage means for, and associated with, each of a number of digital input signals in a group of such signals, and each storage means being adapted to store a number and a sign representing the associated signal in each group, countdown, means for counting the numbers stored by the storage means down to zero at selectable predetermined rates, individual to each storage means, and control means for forming the sum of the times taken to count down the numbers stored by the storage means, taking account, in forming the said sum, of the signs of the numbers counted down, the control means also being adapted to provide a drive signal for an actuator for a time, and in a direction, determined by the sum and its sign, respectively.
Claim 3
Dependent Claim
90 words
Apparatus according to claim 1, wherein the control means includes first logic means for counting all numbErs of like sign, in the storage means, down one after the other while at the same time counting down one after another all numbers of opposite sign, if any, and second logic means for providing the drive signal only when one number is being counted down at a time, the drive signal having a characteristic determining the direction of drive of the actuator dependent on the sign of the number being counted down.
Claim 4
Dependent Claim
54 words
Apparatus according to claim 2 wherein the means for counting numbers down includes an oscillator, coupled to a multistage frequency division circuit having a number of output terminals at which different frequencies can be obtained, and mans for selecting said output terminals and coupling them to individual storage means to control rate of countdown.
Claim 5
Dependent Claim
50 words
First and second actuator drive apparatus according to claim 2 including third logic means for interconnecting the first and second apparatus to provide override control for the first apparatus to ensure that the second apparatus provides its drive signal only if the first apparatus does not provide such a signal.
Claim 6
Dependent Claim
161 words
Control apparatus including actuator drive apparatus according to claim 2 including a plurality of measurement means, each of which has a digital output and is adapted to measure a quantity to be controlled, selection means for repeatedly selecting the outputs of the measurement means one at a time and for selecting, at the same time, the appropriate one of a plurality of numerical inputs to the apparatus which are representative, at that time, of desired values of the quantities measured, and calculating means for determining errors by finding the difference between the concurrent selected output and selected numerical input, there being one said actuator drive apparatus having one storage means and one countdown means, associated with each measurement means, for multiplying the difference derived from measurement by that measurement means by a predetermined constant proportional to the predetermined countdown rate for that storage means, the actuator or said one apparatus controlling, at least partially, the quantity measured by that measurement means.
Claim 7
Dependent Claim
72 words
Control apparatus according to claim 5 including a number of stores one for each measurement means, and adapted to hold the error relating to a quantity measured by that measuring means, wherein the calculating means is additionally adapted to determine the difference between each error and the previous error transferred from the appropriate store, and each said actuator drive apparatus has two said storage means one each for the two differences derived.
Claim 8
Dependent Claim
116 words
Control apparatus according to claim 6 wherein the selection means includes a matrix of spaced conductors, one group of the conductors forming the rows of the matrix and another group forming the columns thereof, the conductors of one group being further divided into subgroups with each conductor in each subgroup representing a number, means for sequentially marking the conductors in the other group by means of a unidirectional voltage, diode means for individually interconnecting the conductors of the two groups at selectable positions where the columns cross the rows whereby each subgroup of wires has conductors marked which together represent one of the said numerical inputs, as each conductor in the said other group is marked.
Claim 9
Dependent Claim
38 words
Control apparatus according to claim 7 wherein the selection means includes scanning means for transferring the outputs of the measurement means, when a measurement is complete, and the appropriate numerical input from the matrix to the calculating means.
Claim 10
Dependent Claim
37 words
Control apparatus according to claim 8 including program interrupt means for interrupting the sequential marking of conductors sand allowing marking to proceed only when one or more conditions in plant controlled by the apparatus have been achieved.
Claim 11
Dependent Claim
30 words
Control apparatus according to claim 5 wherein the calculating means calculates at least two of the terms, preceded by constants K1, K2 . . . Kp, in the following equation:
Claim 12
Dependent Claim
107 words
Control apparatus according to claim 7 including feed-forward measurement means, for at least one of the actuators, having a digital output and being adapted to measure a quantity to be controlled at a point before the actuator acts to control the said quantity and third logic means for interconnecting the first and second apparatus to provide override control for the first apparatus to ensure that the second apparatus provides its drive signal only if the first apparatus does not provide such a signal, the feed-forward measurement means being coupled to the first or second actuator-drive apparatus and the other actuator-drive apparatus being coupled to the calculating means.
Claim 13
Dependent Claim
59 words
Control apparatus according to claim 11 wherein each measuring means includes a voltage-to-frequency converter which provides a signal whose frequency is dependent upon an analog voltage representative of a quantity, a gate to which the signal so provided is applied, and means for opening the gate for a predetermined time to give a frequency count representative of the quantity.
Claim 14
Dependent Claim
16 words
Apparatus according to claim 12 including a plurality of actuators, each actuator comprising an induction motor.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-02-14 | 1975-08-16 | 1976-02-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-02-14 | 1979-08-16 | 1980-02-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-02-14 | 1983-08-16 | 1984-02-15 | $7700.00 | Window Closed / Lapsed |