US4777603A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Controller for multiple-axis machine
Assignee: Cybermation Inc
•
Filing: 1985-03-08
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Granted: 1988-10-11
•
Expires: 2005-03-08
Abstract
Abstract Movement of a tool relative to a workpiece along each one of a plurality of axes is controlled by digitally providing a train of digital pulses to an electromechanical actuator and by digitally modulating the pulse widths (without an intervening conversion to analog form) so that electrical energy is carried in the pulse train at rates which will cause the actuator to tend to produce an intended sequence of speeds and positions.
Inventors
- 👤 Edward C. Woodman
- 👤 William F. Ellersick
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 10:42
CPC Classifications
G; G05; G05B; G05B19/00; G05B19/02; G05B19/18; G05B19/19; G05B19/21; G05B19/25; G05B19/251; G05B19/253; G05B2219/00; G05B2219/30; G05B2219/42; G05B2219/42237
Claims Analysis
Total Claims: 34
Claim 1
Independent Claim
189 words
Apparatus to control the movement of a tool relative to a workpiece along each one of a plurality of axes in accordance with a predetermined sequence of intended speeds and positions, said movement along each axis being produced by an electromechanical actuator, said apparatus comprising a digital pulse generator arranged to generate a train of periodic digital output pulses and to deliver said pulse train directly to said actuator, and a digital controller arranged to receive command signals that represent said sequence of intended speeds and positions, and to generate corresponding digital control signals for said digital pulse generator to control the widths of said digital output pulses in said pulse train so that electrical energy is carried in said pulse train at rates which will cause said actuator to tend to produce said sequence of intended speeds and positions, said digital controller being further arranged to approximate said intended positions as a hypothetical series of connected linear steps of movement, and said intended speeds as hypothetical rates at which said linear steps occur, and to base said digital control signals in part on said steps and said rates.
Claim 2
Dependent Claim
189 words
Apparatus to control the movement of a tool relative to a workpiece along each one of a plurality of axes in accordance with a predetermined sequence of intended speeds and positions, said movement along each axis being produced by an electromechanical actuator, said apparatus comprising a digital pulse generator arranged to generate a train of periodic digital output pulses and to deliver said pulse train directly to said actuator, and a digital controller arranged to receive command signals that represent said sequence of intended speeds and positions, and to generate corresponding digital control signals for said digital pulse generator to control the widths of said digital output pulses in said pulse train so that electrical energy is carried in said pulse train at rates which will cause said actuator to tend to produce said sequence of intended speeds and positions, said digital controller being further arranged to approximate said intended positions as a hypothetical series of connected linear steps of movement, and said intended speeds as hypothetical rates at which said linear steps occur, and to base said digital control signals in part on said steps and said rates.
Claim 3
Dependent Claim
52 words
The apparatus of claim 1 further comprising a digital encoder arranged to sense the position of said tool relative to said workpiece and to provide corresponding digital actual position signals, and wherein said digital controller is further arranged to base said digital control signals in part on said digital actual position signals.
Claim 4
Dependent Claim
52 words
The apparatus of claim 2 wherein said digital controller comprises a digital speed calculator arranged to provide digital actual speed signals based on a time sequence of said digital actual position signals, and wherein said digital controller is further arranged to base said digital control signals on said digital actual speed signals.
Claim 5
Dependent Claim
39 words
The apparatus of claim 3 wherein said digital controller is further arranged to base said digital control signals on a speed error gain factor times the difference between said digital actual speed signals and a current intended speed signal.
Claim 6
Dependent Claim
22 words
The apparatus of claim 4 wherein said speed error gain factor reflects a characteristic speed error of said movement of said tool.
Claim 7
Dependent Claim
38 words
The apparatus of claim 2 wherein said digital controller is further arranged to base said digital control signals on a lag gain factor times the difference between said digital actual position signals and a current intended position signal.
Claim 8
Dependent Claim
31 words
The apparatus of claim 1 wherein said pulse train has a frequency in the audible range higher than 60 hertz, preferably between 100 hertz and 5 kilohertz, most preferably 1 kilohertz.
Claim 9
Dependent Claim
47 words
The apparatus of claim 1 wherein said digital pulse generator is further arranged to generate said pulses with a first polarity for motion in one direction along said axis and with the opposite polarity from said first polarity for motion in the opposite direction along said axis.
Claim 10
Dependent Claim
41 words
The apparatus of claim 1 wherein said digital controller further comprises a dithering control for causing said digital pulse generator to deliver digital output pulses that maintain said actuator in a warmed-up condition, but do not cause movement along said axis.
Claim 11
Dependent Claim
36 words
The apparatus of claim 9 wherein said dithering controller causes said digital generator to deliver alternate digital output pulses of a first polarity and intervening digital output pulses of a polarity opposite to said first polarity.
Claim 12
Dependent Claim
52 words
The apparatus of claim 8 wherein said digital pulse generator is further arranged to be capable of delivering no output pulses and hence no energy to said actuator, and said digital controller comprises a shut off control which causes said digital generator to deliver no output pulses during periods of signal interference.
Claim 13
Dependent Claim
39 words
The apparatus of claim 1 wherein said digital pulse generator comprises a pulse width modulator which generates digital logic pulses, and a digital switching amplifier which receives and amplifies said logic pulses to form said digital output pulse train.
Claim 14
Dependent Claim
49 words
The apparatus of claim 1 wherein said digital pulse generator generates said pulse train at a characteristic modulation frequency, and said digital controller is further arranged to update said digital control signals at an update rate which is at least an order of magnitude slower than said modulation frequency.
Claim 15
Dependent Claim
12 words
The apparatus of claim 13 wherein said update rate is 100 hertz.
Claim 16
Dependent Claim
40 words
The apparatus of claim 1 wherein said digital controller comprises a step generator which operates in a succession of cycles and in each cycle counts a number of steps corresponding to a current intended position and a current intended speed.
Claim 17
Dependent Claim
35 words
The apparatus of claim 15 wherein the size of each said step is sufficiently small relative to the inertia characterizing the movement of said tool so that the hypothetical steps result in smooth tool movement.
Claim 18
Dependent Claim
11 words
The apparatus of claim 16 wherein each said step is 0.0005".
Claim 19
Dependent Claim
24 words
The apparatus of claim 16 wherein said digital controller further comprises a step generator to generate said steps by a step-wise linear interpolation algorithm.
Claim 20
Dependent Claim
37 words
The apparatus of claim 1 wherein said digital controller comprises a speed/accuracy control which governs the speed and accuracy of said movement based on a selectable speed/accuracy parameter by adjusting the rates at which said steps occur.
Claim 21
Dependent Claim
38 words
The apparatus of claim 19 wherein for a given said speed/accuracy parameter said speed can be varied over a range by adjusting the widths of said pulses, and said range can be varied by adjusting said speed/accuracy parameter.
Claim 22
Dependent Claim
17 words
The apparatus of claim 19 wherein said speed can be as high as 90,000 inches per minute.
Claim 23
Dependent Claim
32 words
The apparatus of claim 1 wherein said digital controller comprises an acceleration/deceleration control which triggers changes in said rates at which said steps occur to cause desired changes in said intended speeds.
Claim 24
Dependent Claim
14 words
The apparatus of claim 1 wherein said actuator is a linear torque DC motor.
Claim 25
Dependent Claim
11 words
The apparatus of claim 1 wherein there are two said axes.
Claim 26
Dependent Claim
11 words
The apparatus of claim 1 wherein there are three said axes.
Claim 27
Dependent Claim
27 words
The apparatus of claim 1 wherein said tool comprises a torch and said workpiece comprises a sheet of metal from which a part is to be cut.
Claim 28
Dependent Claim
13 words
The apparatus of claim 1 wherein said digital controller comprises a programmed microprocessor.
Claim 29
Dependent Claim
41 words
The apparatus of claim 1 wherein said digital controller further comprises a dithering control for causing said digital pulse generator to deliver digital output pulses that maintain said actuator in a warmed-up condition, but do not cause movement along said axis.
Claim 30
Dependent Claim
36 words
The apparatus of claim 28 wherein said dithering controller causes said digital generator to deliver alternate digital output pulses of a first polarity and intervening digital output pulses of a polarity opposite to said first polarity.
Claim 31
Dependent Claim
184 words
Apparatus to control the movement of a tool relative to a workpiece along each one of a plurality of axes in accordance with a predetermined sequence of intended speeds and positions, said movement along each axis being produced by an electromechanical actuator, said apparatus comprising a digital pulse generator arranged to generate a train of periodic digital output pulses and to deliver said pulse train directly to said actuator, and a digital controller arranged to receive command signals that represent said sequence of intended speeds and positions, and to generate corresponding digital control signals for said digital pulse generator to control the widths of said digital output pulses in said pulse train so that electrical energy is carried in said pulse train at rates which will cause said actuator to tend to produce said sequence of intended speeds and positions, said digital pulse generator being further arranged to be capable of delivering no output pulses and hence no energy to said actuator, said digital controller comprising a shut-off control which causes said digital generator to deliver no output pulses during periods of signal interference.
Claim 32
Dependent Claim
184 words
Apparatus to control the movement of a tool relative to a workpiece along each one of a plurality of axes in accordance with a predetermined sequence of intended speeds and positions, said movement along each axis being produced by an electromechanical actuator, said apparatus comprising a digital pulse generator arranged to generate a train of periodic digital output pulses and to deliver said pulse train directly to said actuator, and a digital controller arranged to receive command signals that represent said sequence of intended speeds and positions, and to generate corresponding digital control signals for said digital pulse generator to control the widths of said digital output pulses in said pulse train so that electrical energy is carried in said pulse train at rates which will cause said actuator to tend to produce said sequence of intended speeds and positions, said digital pulse generator being further arranged to be capable of delivering no output pulses and hence no energy to said actuator, said digital controller comprising a shut-off control which causes said digital generator to deliver no output pulses during periods of signal interference.
Claim 33
Independent Claim
170 words
A method of controlling the movement of a tool relative to a workpiece along each one of a plurality of axes in accordance with a predetermined sequence of intended speeds and positions, said movement along each axis being produced by an electromechanical actuator, said method comprising generating a train of periodic digital output pulses and delivering said pulse train directly to said actuator, approximating said intended positions as a hypothetical series of connected linear steps of movement, and said intended speeds as hypothetical rates at which said linear steps occur, and basing said digital control signals in part on said steps and said rates, and in response to command signals that represent said sequence of intended speeds and positions, generating corresponding digital control signals for said digital pulse generator to control the widths of said digital output pulses in said pulse train so that electrical energy is carried in said pulse train at rates which will cause said actuator to tend to produce said sequence of intended speeds and positions.
Claim 34
Independent Claim
170 words
A method of controlling the movement of a tool relative to a workpiece along each one of a plurality of axes in accordance with a predetermined sequence of intended speeds and positions, said movement along each axis being produced by an electromechanical actuator, said method comprising generating a train of periodic digital output pulses and delivering said pulse train directly to said actuator, approximating said intended positions as a hypothetical series of connected linear steps of movement, and said intended speeds as hypothetical rates at which said linear steps occur, and basing said digital control signals in part on said steps and said rates, and in response to command signals that represent said sequence of intended speeds and positions, generating corresponding digital control signals for said digital pulse generator to control the widths of said digital output pulses in said pulse train so that electrical energy is carried in said pulse train at rates which will cause said actuator to tend to produce said sequence of intended speeds and positions.
References Cited (Backward Citations)
US3887796A
Cited
US3857025A
Cited
US3812474A
Cited
US4396976A
Cited
US3797320A
Cited
US3878983A
Cited
US4164693A
Cited
US4060851A
Cited
US4068297A
Cited
US4135239A
Cited
US4059746A
Cited
US4041287A
Cited
US4138632A
Cited
US4225928A
Cited
US4259626A
Cited
US4270868A
Cited
US4404507A
Cited
US4376970A
Cited
US4571530A
Cited
US4588936A
Cited
US4562393A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-10-11 | 1992-04-11 | 1992-10-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-10-11 | 1996-04-11 | 1996-10-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-10-11 | 2000-04-11 | 2000-10-11 | $7700.00 | Window Closed / Lapsed |