US3701888A
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Time shared position feedback system for numerical control
Assignee: Bendix Corp
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Filing: 1970-08-05
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Granted: 1972-10-31
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Expires: 1990-08-05
Abstract
Abstract A numerical control system for machines having a plurality of movable elements wherein position feedback signals are generated by transforming a phase shift into a digital count indicating absolute position in either a positive or negative scale range. The respective feedback signals are time multiplexed to reduce hardware.
Inventors
- 👤 George H Mcdaniel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 02:21
CPC Classifications
G; G05; G05B; G05B19/00; G05B19/02; G05B19/18; G05B19/19; G05B19/33; G05B19/37; G05B19/371
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
123 words
A numerical control system comprising: first means for developing an alternating signal which cyclically varies in phase according to the displacement of a movable machine element; second means for determining the phase difference between said signal and a periodically occurring reference signal and generating a digital count representing said phase difference; position storage means for containing a digital position quantity; and third means for calculating from the digital count and the digital position quantity a new digital position quantity indicating both the direction and total displacement of said element relative to an arbitrarily selected zero reference point, said first means additionally comprising means responsive to a sinusoidal waveform for developing a square waveform of a phase corresponding to that of the sinusoidal waveform.
Claim 2
Dependent Claim
123 words
A numerical control system comprising: first means for developing an alternating signal which cyclically varies in phase according to the displacement of a movable machine element; second means for determining the phase difference between said signal and a periodically occurring reference signal and generating a digital count representing said phase difference; position storage means for containing a digital position quantity; and third means for calculating from the digital count and the digital position quantity a new digital position quantity indicating both the direction and total displacement of said element relative to an arbitrarily selected zero reference point, said first means additionally comprising means responsive to a sinusoidal waveform for developing a square waveform of a phase corresponding to that of the sinusoidal waveform.
Claim 3
Dependent Claim
51 words
A system as defined in claim 1 wherein said second means comprises count control means receiving said alternating signal and said reference signal and responsive to a coincidence thereof to count at a predetermined rate only when the machine element is in a positive range relative to the zero reference point.
Claim 4
Dependent Claim
41 words
A system as defined in claim 1 wherein said second means includes means for deferring a count until the first full cycle of said alternating signal whenever the machine element is in a negative range relative to the zero reference point.
Claim 5
Dependent Claim
46 words
A system as defined in claim 1 wherein the third means comprises a counter for containing said digital count, a shift register for receiving said count from said counter in parallel, the shift register being connected to transfer said count serially to said position storage means.
Claim 6
Dependent Claim
67 words
A system as defined in claim 1 wherein said digital count includes a plurality of lesser significant digits, said third means including logic for producing a carry signal to the next most significant digit in said digital position quantity whenever the digital count is less than the digital position quantity by a predetermined amount thus indicating a cycle completion in said alternating signal in a phase-increasing direction.
Claim 7
Dependent Claim
55 words
A system as defined in claim 5 wherein the third means includes logic for producing a borrow signal from the next most significant digit in said digital position quantity whenever the digital count exceeds the digital position quantity by a predetermine amount thus indicating a cycle completion in said alternating signal in a phase-decreasing direction.
Claim 8
Dependent Claim
65 words
A system as defined in claim 1 including a plurality of said first means for producing respective alternating signals representing displacement of said elemeNt in respective directions; a plurality of said position storage means for digital position quantities associated with respective directions; and multiplexer means for applying the alternating signals and the counts derived thereform to the second and third means in a time-staggered sequence.
Claim 9
Dependent Claim
85 words
A numerical control system for a machine having an element movable controllably along each of several axes comprising: means for providing position command signals for the respective devices; means for providing position feedback signals from each of said devices; an arithmetic unit for producing position error signals for each of said devices as a function of the difference between the position command signals and the position feedback signals; and multiplexer means for applying the position feedback signals to the arithmetic unit in a time-divided sequence.
Claim 10
Dependent Claim
85 words
A numerical control system for a machine having an element movable controllably along each of several axes comprising: means for providing position command signals for the respective devices; means for providing position feedback signals from each of said devices; an arithmetic unit for producing position error signals for each of said devices as a function of the difference between the position command signals and the position feedback signals; and multiplexer means for applying the position feedback signals to the arithmetic unit in a time-divided sequence.
Claim 11
Dependent Claim
76 words
A numerical control system as defined in claim 8 wherein the multiplexer means includes means responsive to substantially sinusoidal position feedback signals for generating respective square waveforms of a phase corresponding to the phase of the sinusoidal signals, said system further including means for generating a phase reference signal, and feedback counter means for determining the phase difference between the square waveforms and the reference signal and providing a digital representation thereof to the arithmetic unit.
Claim 12
Dependent Claim
40 words
A numerical control system as defined in claim 9 wherein the feedback conter includes means for indicating whether the position feedback signal for each cycle of the measurement sequence is greater or less than the signal for the succeeding cycle.
Claim 13
Dependent Claim
86 words
A numerical control system as defined in claim 9 wherein the feedback counter includes means for generating a count having no more than a predetermined number of digits, means for generating a carry signal to the next most significant digit for increasing feedback position changes, means for generating a borrow signal to the next most significant digit for decreasing feedback position changes, and means responsive to at least the next most significant digit to determine when the count passes through an arbitrarily selected absolute zero position.
References Cited (Backward Citations)
US3165680A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-10-31 | 1976-05-01 | 1976-10-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-31 | 1980-05-01 | 1980-10-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-31 | 1984-05-01 | 1984-10-31 | $7700.00 | Window Closed / Lapsed |