Patent US5034672A successfully refreshed from Google Patents.
US5034672A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Reference-point return method
Assignee: Fanuc Corp
•
Filing: 1989-02-15
•
Granted: 1991-07-23
•
Expires: 2009-02-15
Abstract
Abstract A reference-point return method for a numerical control system. When a return is made to a reference point, a numerical control unit (21) reads an absolute position of a motor (23) within one revolution thereof from an absolute position detector (24), obtains a distance B from a predetermined motor point (a grid point) to the absolute position that has been read, and initially sets the distance B as a command position REF n from the grid point. Thereafter, the numerical control unit (21) outputs a move command value ΔR n to a digital servo-circuit (22) every predetermined time ΔT, updates a commanded position REF n in accordance with the equation REF.sub.n +ΔR.sub.n →REF.sub.n obtains REF n after a deceleration limit switch (25) is depressed, and outputs (N-REF n ) to the digital servo-circuit (22) as a final commanded traveling distance ΔR n to return the movable element to a reference-point position set at a predetermined grid point.
Inventors
- 👤 Keiji Sakamoto
- 👤 Shunsuke Matsubara
- 👤 Kaname Matsumoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 08:06
CPC Classifications
G; G05; G05B; G05B19/00; G05B19/02; G05B19/18; G05B19/19; G05B19/21; G05B19/23; G05B19/231; G05B19/401; G05B19/4015; G05B2219/00; G05B2219/30; G05B2219/50; G05B2219/50025
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
248 words
A method for returning a movable element of a machine tool to a reference point using a motor having a grid point and driven by move commands, said method comprising the steps of: (a) receiving an absolute position of the motor; (b) calculating an initial motor position based on the absolute position and the grid point; (c) initially setting a commanded position based on a distance from the grid point to the initial motor position; (d) executing rapid-traverse processing using the move commands to gradually increase an actual velocity of the movable element towards the reference point to a rapid-traverse velocity; (e) updating the commanded position from the grid point to produce an updated commanded position based on a travelling distance occurring every predetermined time period; (f) determining if a deceleration signal requests deceleration of the movable element; (g) executing deceleration processing to gradually decrease the actual velocity of the movable element towards the reference point to a predetermined low velocity when said determining in step (f) determines that deceleration is requested by the deceleration signal; (h) determining if the deceleration signal no longer requests deceleration of the movable element; (i) updating the commanded position at a next time period of the predetermined time period after said determining in step (h) determines that deceleration is no longer requested; (j) calculating a final move command value based on the commanded position obtained in step (i); and (k) outputting the final move command and the move commands to the motor.
Claim 2
Independent Claim
248 words
A method for returning a movable element of a machine tool to a reference point using a motor having a grid point and driven by move commands, said method comprising the steps of: (a) receiving an absolute position of the motor; (b) calculating an initial motor position based on the absolute position and the grid point; (c) initially setting a commanded position based on a distance from the grid point to the initial motor position; (d) executing rapid-traverse processing using the move commands to gradually increase an actual velocity of the movable element towards the reference point to a rapid-traverse velocity; (e) updating the commanded position from the grid point to produce an updated commanded position based on a travelling distance occurring every predetermined time period; (f) determining if a deceleration signal requests deceleration of the movable element; (g) executing deceleration processing to gradually decrease the actual velocity of the movable element towards the reference point to a predetermined low velocity when said determining in step (f) determines that deceleration is requested by the deceleration signal; (h) determining if the deceleration signal no longer requests deceleration of the movable element; (i) updating the commanded position at a next time period of the predetermined time period after said determining in step (h) determines that deceleration is no longer requested; (j) calculating a final move command value based on the commanded position obtained in step (i); and (k) outputting the final move command and the move commands to the motor.
Claim 3
Dependent Claim
24 words
A method according to claim 1, wherein the absolute position received in position (a) is one of N positions of an absolute position detector.
Claim 4
Dependent Claim
25 words
A method according to claim 2, wherein steps (b)-(i) are performed by a computerized numerical control unit, and wherein the move commands are digital signals.
Claim 5
Dependent Claim
49 words
A method according to claim 3, wherein said updating in step (e) is performed every predetermined time period according to the following equation: REF.sub.n +ΔR.sub.n →REF.sub.n+1 where REF n is the commanded position, ΔR n is the move command, and REF n+1 is the commanded position after being updated.
References Cited (Backward Citations)
US4481588A
Cited
US4513234A
Cited
US4575666A
Cited
US4647827A
Cited
US4680520A
Cited
US4744022A
Cited
US4782275A
Cited
US4827203A
Cited
US4847777A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-07-22 | 1995-01-21 | 1995-07-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-07-22 | 1999-01-21 | 1999-07-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-07-22 | 2003-01-21 | 2003-07-23 | $7700.00 | Window Closed / Lapsed |