US3794814A
Expired / Lapsed
US
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Continuous dynamic error monitoring device for numerically controlled machines
Assignee: United States Atomic Energy Commission
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Filing: 1973-02-15
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Granted: 1974-02-26
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Expires: 1993-02-15
Abstract
Abstract A dynamic error monitoring system has been provided which measures the instantaneous value of a positionable machine member by direct, instantaneous and continuous comparison between movement command pulses of a discrete value with pulses of the same discrete value from an independent distance measuring device such as command pulses from a numerical control unit and pulses from an interferometer indicative of the positionable member movement from a reference position. Command pulses from the numerical control unit are compared with the laserinterferometer-derived pulses in a bidirectional counter following suitable scaling, steering, and anticoincidence testing. The net count output of the counter representing the dynamic error is converted to an analog signal that is displayed on a recorder. The system gives a continuous record of the dynamic machine tool position over the entire length of the positionable member travel as well as the static positioning error.
Inventors
- 👤 T Davidson
- 👤 C Lay
- 👤 J Burkhardt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 06:21
CPC Classifications
H; H03; H03K; H03K21/00; H03K21/02; G; G05; G05B; G05B19/00; G05B19/02; G05B19/18; G05B19/406; G05B19/4063; G05B2219/00; G05B2219/30; G05B2219/37; G05B2219/37275; G05B2219/37619
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
375 words
A position error monitoring system for a numerically controlled machine having a positionable member driven by a drive means when command pulses from a numerical control unit are fed to said drive means for commanding movement of said pOsitionable member along a commanded direction path, comprising: a bidirectional counter having an up count and down count input and digital output; a digital-to-analog converter connected to the digital output of said counter to produce an analog signal at an output thereof proportional to the count in said counter; means responsive to increments of movement of said positionable member for generating feedback pulses at a first output corresponding to the increments of movement in the commanded direction and at a second output corresponding to the increments of movement in the direction opposite said commanded direction; an anticoincidence circuit including a clock pulse generator, a first flip-flop having at least set and reset outputs and a toggle input connected to the output of said clock pulse generator so that said set and reset outputs are alternately activated at a frequency of one-half the clock frequency, first, second and third bistable storage means operable to be set, respectively, in response to randomly generated pulses from said numerical control unit, said first output of said feedback generating means and said second output of said feedback generating means, first and second normally disabled bistable switching means each having a toggle input connected, respectively, to said set and reset outputs of said first flipflop for alternately resetting said first bistable storage means and said second and third bistable storage means responsive to the set condition of a corresponding one of said first, second and third bistable storage means, a first output circuit means responsive to the resetting of said first or third bistable storage means for applying a pulse to the up count input of said counter, and a second output circuit means responsive to the resetting of said second bistable storage means for applying a pulse to the down count input of said counter; and analog recording means responsive to the output of said digitalto-analog converter for recording said analog signal, thereby recording the position error of said positionable member moved along the commanded direction path by said numerical control unit.
Claim 2
Dependent Claim
375 words
A position error monitoring system for a numerically controlled machine having a positionable member driven by a drive means when command pulses from a numerical control unit are fed to said drive means for commanding movement of said pOsitionable member along a commanded direction path, comprising: a bidirectional counter having an up count and down count input and digital output; a digital-to-analog converter connected to the digital output of said counter to produce an analog signal at an output thereof proportional to the count in said counter; means responsive to increments of movement of said positionable member for generating feedback pulses at a first output corresponding to the increments of movement in the commanded direction and at a second output corresponding to the increments of movement in the direction opposite said commanded direction; an anticoincidence circuit including a clock pulse generator, a first flip-flop having at least set and reset outputs and a toggle input connected to the output of said clock pulse generator so that said set and reset outputs are alternately activated at a frequency of one-half the clock frequency, first, second and third bistable storage means operable to be set, respectively, in response to randomly generated pulses from said numerical control unit, said first output of said feedback generating means and said second output of said feedback generating means, first and second normally disabled bistable switching means each having a toggle input connected, respectively, to said set and reset outputs of said first flipflop for alternately resetting said first bistable storage means and said second and third bistable storage means responsive to the set condition of a corresponding one of said first, second and third bistable storage means, a first output circuit means responsive to the resetting of said first or third bistable storage means for applying a pulse to the up count input of said counter, and a second output circuit means responsive to the resetting of said second bistable storage means for applying a pulse to the down count input of said counter; and analog recording means responsive to the output of said digitalto-analog converter for recording said analog signal, thereby recording the position error of said positionable member moved along the commanded direction path by said numerical control unit.
Claim 3
Dependent Claim
115 words
The error monitoring system as set forth in claim 1 wherein said first, second, and third bistable storage means are corresponding first, second and third R/D flip-flops each having set and reset inputs and at least a set output, said set inputs being connected, respectively, to receive the command pulses, feedback pulses from said first output of said feedback pulse generating means, and feedback pulses from said second output of said feedback generating means, and wherein said first and second normally disabled bistable switching means are corresponding first and second J-K flip-flops connected to be set by the first pulse applied from said first-named flip-flop following the application of one of said randomly generated pulses.
Claim 4
Dependent Claim
114 words
The error monitoring system as set forth in claim 2 wherein said first output circuit means includes a first one-shot multivibrator connected to the set output of said first R/S flip-flop, a second one-shot multivibrator connected to the set output of said set output of said third R/S flip-flop and an OR gate having first and second inputs connected, respectively, to the outputs of said first and second one-shots and an output connected to said up count input of said counter and wherein said second output circuit means includes a third one-shot multivibrator connected to the output of said second R/S flip-flop and an output connected to the down count input of said counter.
Claim 5
Dependent Claim
27 words
The error monitoring system as set forth in claim 3 wherein said feedback pulse generating means includes an interferometer for monitoring the movement of said positionable member.
Claim 6
Dependent Claim
33 words
The error monitoring system as set forth in claim 4 further including scaling means for scaling the feedback pulses from said interferometer to correspond to the incremental movement represented by said command pulses.
Claim 7
Dependent Claim
55 words
The error monitoring system as set forth in claim 5 wherein said feedback pulse generating means includes means responsive to a direction command from said numerical control unit for reversing the first and second outputs of said feedback pulse generating means in response to a change in the commanded direction path of said positionable member.
Claim 8
Dependent Claim
19 words
The error monitoring system as set forth in claim 6 wherein said analog recording means is a strip-chart recorder.
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) | 1977-02-25 | 1977-08-27 | 1978-02-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-25 | 1981-08-27 | 1982-02-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-25 | 1985-08-27 | 1986-02-26 | $7700.00 | Window Closed / Lapsed |