US3555252A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Learning control of actuators in control systems
Assignee: Leeds and Northrup Co
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Filing: 1967-05-11
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Granted: 1971-01-12
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Expires: 1987-05-11
Abstract
Abstract A learning control technique which learns the characteristics of actuators, such as electric drive units, and provides actuator signals based on them. The command signal, which is related to the actuator characteristic, and from which the actuator signal is derived, is stored in the computer memory and is modified by an amount related to a function of the error between the actual movement and the desired movement of the actuator. A specific application of learning control to both electric drive units and pneumatic actuators is described.
Inventors
- 👤 Murray Garden
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 16:49
CPC Classifications
G; G05; G05B; G05B13/00; G05B13/02; G05B13/0265
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
211 words
A control system for controlling a controlled variable to produce an actuator signal for controlling an actuator, said system operating in a plurality of control cycles, said system being responsive to a desired correction signal, said desired correction signal being derived from the actual controlled variable and the desired value of the controlled variable, said controlled variable of said system being responsive to said actuator, said system comprising: storage means for storing a command signal, and a desired correction signal; means for deriving an actuator signal from said stored command signal; an actuator, said actuator signal being applied to said actuator; means for generating an actual correction signal representative of the actual change in the value of said controlled variable subsequent to the application of said actuator signal to said actuator; means for generating an error signal which is a function of said desired correction signal and said actual correction signal in each cycle; and means for modifying said command signal in accordance with said error signal for reducing said error signal in a subsequent control cycle, whereby the modified command signal approaches a value such that the actuator signal derived from the command signal in a subsequent cycle produces an actual change in controlled variable that approaches the desired correction.
Claim 2
Dependent Claim
211 words
A control system for controlling a controlled variable to produce an actuator signal for controlling an actuator, said system operating in a plurality of control cycles, said system being responsive to a desired correction signal, said desired correction signal being derived from the actual controlled variable and the desired value of the controlled variable, said controlled variable of said system being responsive to said actuator, said system comprising: storage means for storing a command signal, and a desired correction signal; means for deriving an actuator signal from said stored command signal; an actuator, said actuator signal being applied to said actuator; means for generating an actual correction signal representative of the actual change in the value of said controlled variable subsequent to the application of said actuator signal to said actuator; means for generating an error signal which is a function of said desired correction signal and said actual correction signal in each cycle; and means for modifying said command signal in accordance with said error signal for reducing said error signal in a subsequent control cycle, whereby the modified command signal approaches a value such that the actuator signal derived from the command signal in a subsequent cycle produces an actual change in controlled variable that approaches the desired correction.
Claim 3
Dependent Claim
37 words
The system recited in claim 1 further including: means responsive to said desired correction signal for changing the operation of said means for modifying said command signal in accordance with the magnitude of said desired correction signal.
Claim 4
Dependent Claim
53 words
The system recited in claim 1 wherein said storage means stores a plurality of command signals, said system further comprising: selection means responsive to said desired correction signal for selecting a command signal representative of a particular segment of an actuator characteristic, said actuator characteristic relating the desired correction and the actuator signal.
Claim 5
Dependent Claim
200 words
The system recited in claim 1 wherein a first group of command signals represents values which will produce the desired correction when said desired correction signal is below a predetermined value, and wherein a second group of said command signals represents values which, when multiplied by said desired correction signal, will produce the desired correction when said desired correction signal is above said predetermined value, said system further including: a comparator for comparing said desired correction signal to said predetermined value to determine the group from which the command signal was selected; selection means responsive to said comparator for selecting one of said first group of command signals when said desired correction signal is below said predetermined value, said selection means being responsive to said comparator for selecting one of said second group of command signals when said desired correction signal is above said predetermined value; and means for multiplying said desired correction signal by a selected one of said second group of said command signals, the output of said means for multiplying being applied to said means for deriving said actuator signal, the selected command signal of said first group of command signals being applied to said deriving means.
Claim 6
Dependent Claim
96 words
The system recited in claim 4 wherein said means for modifying said command signal further includes: divider means, said desired correction signal and said actual correction signal being applied to said divider means to produce an error factor signal representing the quotient of desired correction to actual correction; a multiplier, said error factor signal being applied to said multiplier; and means responsive to said comparator for applying a selected one of said second group of command signals to said multiplier when said desired correction signal is above said predetermined value to produce said modified command signal.
Claim 7
Dependent Claim
140 words
The system recited in claim 5 further including: a comparator for comparing said actual correction signal to said predetermined value; a difference circuit, said actual correction signal and said desired correction signal being applied to said difference circuit to produce an error signal at the output thereof; a multiplier, said error signal being applied to said multiplier and a signal representing a constant being applied to said multiplier to produce a command correction signal at the output thereof; and means responsive to the comparison of said desired correction signal and said actual correction signal to said predetermined value to modify the selected command signal from said second group of command signals by a function of said command correction signal when said desired correction signal is above said predetermined value but said actual correction signal is less than said predetermined value.
Claim 8
Dependent Claim
114 words
The system recited in claim 4 wherein said means for modifying said command signal further includes: a difference circuit, said actual correction signal and said desired correction signal being applied to said difference circuit to produce an error signal at the output thereof; a multiplier, said error signal being applied to said multiplier and a signal representing a constant being applied to said multiplier to produce a command correction signal at the output thereof; An adder, said command correction signal being applied to said adder; and means responsive to said comparator for applying one of said first group of command signals to said adder when said desired correction signal is below said predetermined value.
Claim 9
Dependent Claim
80 words
The system recited in claim 1 wherein a set point signal representing the set point of said controlled variable is applied to the input of said system, said system further comprising: means responsive to said set point signal and to a signal representing said controlled variable for producing a difference signal representing the difference between said set point and said controlled variable; and a controller, said difference signal being applied to said controller, said controller producing said desired correction signal.
Claim 10
Dependent Claim
31 words
The system recited in claim 1 further including: a valve, said actuator controlling said valve; and means sensing the position of said valve for producing a signal representing said controlled variable.
Claim 11
Dependent Claim
32 words
The system recited in claim 1 wherein said desired correction signal, actual correction signal, error signal and command signal are analogue signals and wherein said means for generating comprise analogue computing devices.
Claim 12
Dependent Claim
183 words
A direct digital computer control system operating in a plurality of control cycles for controlling an actuator for a control element having output characteristics which vary as a function of actuator signal and which vary with environmental conditions, including: means for generatinG during each cycle a signal representing the actual position of said actuator; means for generating the desired correction for said actuator for each cycle; means for storing a plurality of command signals from which actuator signals are derived to produce a given output from a particular segment of said characteristics; means responsive to said desired correction outputs for selecting a command signal corresponding with the desired correction; means for deriving an actuator signal from the selected command signal; means for moving the control element in response to an actuator signal derived from the selected command signal; the improvement comprising: means for producing an error signal in each control cycle in response to the desired position of the control element and the final position of the control element; and means for modifying the selected command signal in accordance with said error signal.
Claim 13
Dependent Claim
183 words
A direct digital computer control system operating in a plurality of control cycles for controlling an actuator for a control element having output characteristics which vary as a function of actuator signal and which vary with environmental conditions, including: means for generatinG during each cycle a signal representing the actual position of said actuator; means for generating the desired correction for said actuator for each cycle; means for storing a plurality of command signals from which actuator signals are derived to produce a given output from a particular segment of said characteristics; means responsive to said desired correction outputs for selecting a command signal corresponding with the desired correction; means for deriving an actuator signal from the selected command signal; means for moving the control element in response to an actuator signal derived from the selected command signal; the improvement comprising: means for producing an error signal in each control cycle in response to the desired position of the control element and the final position of the control element; and means for modifying the selected command signal in accordance with said error signal.
Claim 14
Independent Claim
193 words
The method of operating a computer in a control system for controlling a controlled variable to produce an actuator signal for controlling an actuator, said system operating in a plurality of control cycles, said system being responsive to a desired correction signal, said controlled variable of said system being responsive to said actuator, said method comprising: storing a desired correction signal; storing a command signal; deriving from said stored command signal an actuator signal; applying said actuator signal to said actuator; positioning said actuator in response to said actuator signal; generating an actual correction signal representative of the actual change in value of said controlled variable subsequent to the application of said actuator signal to said actuator; generating an error signal which is a function of said desired correction signal and said actual correction signal in each cycle; and modifying said command signal in accordance with said error signal for reducing said error signal in a subsequent control cycle, whereby the modified command signal approaches a value such that the actuator signal derived from the command signal in a subsequent cycle produces an actual change in controlled variable that approaches the desired correction.
Claim 15
Independent Claim
193 words
The method of operating a computer in a control system for controlling a controlled variable to produce an actuator signal for controlling an actuator, said system operating in a plurality of control cycles, said system being responsive to a desired correction signal, said controlled variable of said system being responsive to said actuator, said method comprising: storing a desired correction signal; storing a command signal; deriving from said stored command signal an actuator signal; applying said actuator signal to said actuator; positioning said actuator in response to said actuator signal; generating an actual correction signal representative of the actual change in value of said controlled variable subsequent to the application of said actuator signal to said actuator; generating an error signal which is a function of said desired correction signal and said actual correction signal in each cycle; and modifying said command signal in accordance with said error signal for reducing said error signal in a subsequent control cycle, whereby the modified command signal approaches a value such that the actuator signal derived from the command signal in a subsequent cycle produces an actual change in controlled variable that approaches the desired correction.
Claim 16
Dependent Claim
87 words
The method recited in claim 12 wherein said actuator has hysteresis characteristics such that the response of said actuator to a particular actuator signal will vary depending upon the direction of the previous motion, and wherein there is a stored hysteresis command signal, said method further comprising: producing an output when the actuator signal calls for motion of said actuator in a direction different from that caused in the previous cycle; and responsive to said last-named output, adding said hysteresis command signal to said stored command signal.
Claim 17
Dependent Claim
42 words
The system recited in claim 13, further comprising: producing an output when the actuator signal in the previous cycle does not cause motion of said actuator; and responsive to said last-named output, adding said hysteresis command signal to the stored command signal.
Claim 18
Dependent Claim
62 words
The method recited in claim 12 wherein said actuator has hysteresis characteristics such that the response of said actuator to a particular actuator signal will vary depending upon the direction of the previous motion, and wherein a hysteresis command signal is stored, said method further comprising: producing an output when the actuator signal calls for motion of said actuator in a direction.
Claim 19
Dependent Claim
31 words
The method recited in claim 12 further comprising: responsive to said desired correction signal, changing the modification of said command signal in accordance with the magnitude of said desired correction signal.
Claim 20
Dependent Claim
48 words
The method recited in claim 12 wherein a plurality of command signals are stored, said method further comprising: responsive to said desired correction signal, selecting a command signal representative of a particular segment of an actuator characteristic, saId actuator characteristic relating the desired correction and the actuator signal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-01-11 | 1974-07-13 | 1975-01-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-01-11 | 1978-07-13 | 1979-01-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-01-11 | 1982-07-13 | 1983-01-12 | $7700.00 | Window Closed / Lapsed |