US3906324A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Positional servo system having three phase speed, numerical control
Assignee: Alfred Herbert Ltd
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Filing: 1973-05-03
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Granted: 1975-09-16
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Expires: 1993-05-03
Abstract
Abstract A machine tool control system is disclosed incorporating a digital computer responsive to a microprogram. Also disclosed is a closed loop servo control system for controlling a variable, in which the error between the demanded and actual values of the variable is monitored and compared with a reference limit to produce a warning signal when the monitored error exceeds the reference limit. The reference limit is varied automatically in dependence on the rate of change of the demanded value of the variable. Further disclosed is a servo control system in which a controlled variable is adjusted towards a demanded value at a speed which initially increases at a predetermined rate and is then held constant. The total required change in the controlled variable is initially stored and, in response to each incremental change in the controlled variable towards the demanded value, the stored value is decremented by a corresponding amount if the variable is changing at the constant speed and by twice the corresponding amount if the variable is changing at the increasing speed. When the stored value has been completely offset, the speed at which the controlled variable changes is reduced to zero at the same rate as the predetermined rate at which it was initially increased towards the constant speed.
Inventors
- 👤 Ian W Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 23:49
CPC Classifications
G; G05; G05B; G05B19/00; G05B19/02; G05B19/18; G05B19/19; G05B19/27; G05B2219/00; G05B2219/30; G05B2219/34; G05B2219/34465; G05B2219/41; G05B2219/41363
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
110 words
In a closed loop machine tool control system incorporating a digital computer for producing a demand signal indicating a desired machine tool control setting, transducing means responsive to the machine tool to produce a feedback signal indicative of the actual machine tool setting, comparing means controlled by the digital computer for comparing the demand and feedback signals to produce an error signal dependent on the difference therebetween, and servo means connected to the machine tool and responsive to the error signal to adjust the machine tool setting in a direction tending to reduce the error signal to zero, the improvement wherein the digital computer functions under control of a micro-program.
Claim 2
Dependent Claim
110 words
In a closed loop machine tool control system incorporating a digital computer for producing a demand signal indicating a desired machine tool control setting, transducing means responsive to the machine tool to produce a feedback signal indicative of the actual machine tool setting, comparing means controlled by the digital computer for comparing the demand and feedback signals to produce an error signal dependent on the difference therebetween, and servo means connected to the machine tool and responsive to the error signal to adjust the machine tool setting in a direction tending to reduce the error signal to zero, the improvement wherein the digital computer functions under control of a micro-program.
Claim 3
Dependent Claim
154 words
In a method of controlling the value of a controlled variable in which, in response to a demanded value of the controlled variable, the controlled variable is caused to change towards the desired value at a speed which initially increases at a predetermined rate from an initial value and is then held constant, the improvement comprising the steps of: summing the incremental changes in the controlled variable towards the demanded value, each such incremental change which takes place while the speed of the controlled variable is increasing at the said rate being counted twice, comparing the sum so formed with the total difference between the demanded and initial values of the controlled variable, and causing the speed of the controlled variable to reduce at a rate equal in value to the said predetermined rate, when the said sum becomes equal to the total difference between the demanded and initial values of the controlled variable.
Claim 4
Dependent Claim
154 words
In a method of controlling the value of a controlled variable in which, in response to a demanded value of the controlled variable, the controlled variable is caused to change towards the desired value at a speed which initially increases at a predetermined rate from an initial value and is then held constant, the improvement comprising the steps of: summing the incremental changes in the controlled variable towards the demanded value, each such incremental change which takes place while the speed of the controlled variable is increasing at the said rate being counted twice, comparing the sum so formed with the total difference between the demanded and initial values of the controlled variable, and causing the speed of the controlled variable to reduce at a rate equal in value to the said predetermined rate, when the said sum becomes equal to the total difference between the demanded and initial values of the controlled variable.
Claim 5
Dependent Claim
13 words
A method according to claim 2, in which the controlled variable is position.
Claim 6
Dependent Claim
43 words
A method according to claim 2, in which the steps of summing the incremental changes in the controlled variable, and causing the speed of the controlled variable to reduce at the said rate, are performed by a digital computer working to a microprogram.
Claim 7
Dependent Claim
148 words
A servo control system, comprising servo means responsive to a demanded value of a controlled variable to alter the actual value of the controlled variable towards the demanded value at a speed which initially increases at a predetermined rate and is then held constant, storage means for storing the value of the total demanded change in the controlled variable, signal generating means responsive to each incremental change in the actual value of the controlled variable towards the demanded value to offset the stored value by a corresponding amount when the controlled variable is changing at the constant speed and by twice the corresponding amount when the controlled variable is changing at the increasing speed, and means operative when the stored value has been completely offset to cause the speed at which the controlled variable changes to reduce to zero at a rate equal to the said predetermined rate.
Claim 8
Dependent Claim
148 words
A servo control system, comprising servo means responsive to a demanded value of a controlled variable to alter the actual value of the controlled variable towards the demanded value at a speed which initially increases at a predetermined rate and is then held constant, storage means for storing the value of the total demanded change in the controlled variable, signal generating means responsive to each incremental change in the actual value of the controlled variable towards the demanded value to offset the stored value by a corresponding amount when the controlled variable is changing at the constant speed and by twice the corresponding amount when the controlled variable is changing at the increasing speed, and means operative when the stored value has been completely offset to cause the speed at which the controlled variable changes to reduce to zero at a rate equal to the said predetermined rate.
Claim 9
Dependent Claim
82 words
A system according to claim 5, where the controlled variable is the position of a controlled member and the controlled member has to move in two or more dimensions to reach the demanded value, and in which the said stored value is the sum of the movements required in each dimension, and in which the said signal generating means comprises means responsive to each incremental change in each of the said dimensions to offset the stored value by the said corresponding amount.
Claim 10
Dependent Claim
194 words
A system according to claim 5, in which the said storage means comprises a digital counter and means responsive to the initial error between the demanded and actual values of the controlled variable to set a number in the counter corresponding to the total number of incremental changes, each of predetermined size, between the demanded and actual values of the controlled variable, and in which the said signal generating means comprises a transducer arranged to monitor the actual value of the controlled variable and to produce a digital signal in response to each said incremental change thereof, means operative when the controlled variable is changing at the said constant rate to change the count of the counter towards zero by a count of one in response to each said digital signal, means operative when the controlled variable is changing at the increasing rate to change the count of the counter towards zero by a count of two in response to the said digital signal, and means operative when the count of the counter reaches zero to cause the rate of change of the controlled variable to reduce to zero at the said predetermined rate.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-15 | 1979-03-17 | 1979-09-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-15 | 1983-03-17 | 1983-09-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-15 | 1987-03-17 | 1987-09-16 | $7700.00 | Window Closed / Lapsed |