Patent EP0260138A2 successfully refreshed from Google Patents.
EP0260138A2
Expired / Lapsed
EP
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Servo control system
Assignee: Fujitsu Ltd
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Filing: 1987-09-10
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Granted: —
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Expires: 2007-09-10
Abstract
Abstract A servo control system having a coarse control unit (2) and a fine control unit (3) wherein a differential gain is changed temporarily for a short period at an initial state of fine control to shorten a settling time and to reduce overshoot. The servo control system includes a controlled system (1) including a controlled object (12) and a drive unit (13), a unit (2) for controlling a speed of the controlled object to move and position the same to a reference position, and a unit (3) having a differential control circuit and for controlling a position of the controlled object to position the controlled object to the reference position, after the speed control unit (2) has moved the controlled object (12) to a position adjacent to the reference position. A differential gain of the differential control circuit is selected from at least two values, a first of which is used at an initial state and a second of which is used after the initial state. The servo control system is applicable to a disc system, a printer, etc.
Inventors
- 👤 Keiichi Kohno
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 20:26
CPC Classifications
G; G05; G05B; G05B11/00; G11; G11B; G11B5/00; G11B5/48; G11B5/58; G11B5/596; G11B5/59605; G11B5/59622; G05B19/00; G05B19/02; G05B19/18; G05B19/19; G05B2219/00; G05B2219/30; G05B2219/37; G05B2219/37313; G05B2219/41; G05B2219/41023; G05B2219/42; G05B2219/42032; G05B2219/42104
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
152 words
A servo control system comprising a controlled system (1) including a controlled object (12) to be position controlled and a drive unit (13) for driving the controlled object; speed control means (2) for controlling the speed of the controlled object (12) through the drive unit (13) to move and position the controlled object to a reference position; and position control means (3) for controlling the position of the controlled object (12) through the drive unit (13) to position the controlled object at the reference position, after the speed control means has moved the controlled object to a position adjacent to the reference position characterised in that the position control means includes differential control means (33) the differential gain of which can be selected from at least two values, a first of which is used during an initial state of position control and a second of which is used after the initial state.
Claim 2
Dependent Claim
152 words
A servo control system comprising a controlled system (1) including a controlled object (12) to be position controlled and a drive unit (13) for driving the controlled object; speed control means (2) for controlling the speed of the controlled object (12) through the drive unit (13) to move and position the controlled object to a reference position; and position control means (3) for controlling the position of the controlled object (12) through the drive unit (13) to position the controlled object at the reference position, after the speed control means has moved the controlled object to a position adjacent to the reference position characterised in that the position control means includes differential control means (33) the differential gain of which can be selected from at least two values, a first of which is used during an initial state of position control and a second of which is used after the initial state.
Claim 3
Dependent Claim
32 words
A servo control system according to claim 1, wherein the first differential gain is greater than the second differential gain, which is used for fine position control of the controlled object (12).
Claim 4
Dependent Claim
48 words
A servo control system according to claim 2, wherein the first differential gain is set as large as possible to shorten settling time and reduce overshoot and/or undershoot, to an extent avoiding oscillation of the controlled system (12), and is used for a short period avoiding the oscillation.
Claim 5
Dependent Claim
191 words
A servo control system according to any of the preceding claims, further comprising master control means (4), and switching means (5) operatively connected between the controlled system (12), the speed control means (2), and the position control means (3), whereby the master control means energises the switching means (5) to connect the controlled system (1) and the speed control means (2) upon receipt of a control command and the reference position and issues a moving value to the speed control means related to the difference between the reference position and the position of the controlled object, the moving value being used for generating a speed reference, issues a gain change signal for selecting the first differential gain of the position control means, and deenergises the switching means (5) to connect the controlled system (1) and the position control means (3) when the controlled object (12) reaches a position adjacent to the reference position and issues the reference position to the position control means (3), the master control means issuing another gain change signal, for selecting the second differential gain, to the position control means (3) after elapse of a certain time.
Claim 6
Dependent Claim
15 words
A servo control system according to claim 4, wherein the elapsed time is a constant.
Claim 7
Dependent Claim
26 words
A servo control system according to claim 4, wherein the elapsed time is the time for the controlled object to be positioned in a positioning range.
Claim 8
Dependent Claim
86 words
A servo control system according to any of the preceding claims, wherein the differential control means (33) has a differential circuit (33a) for differentiating a position signal indicating a position of the controlled object (12), a first amplifier circuit amplifying the differential signal, a second amplifier circuit (33c) for amplifying a current signal indicating a drive current of the drive unit (13) and the amplified differential signal and for adding the amplified current signal and the further amplified differential signal, and a gain change circuit (33b).
Claim 9
Dependent Claim
29 words
A servo control system according to claim 7, wherein the gain change circuit (33b) changes a differential coefficient of the differential circuit (33a) in response to a state change.
Claim 10
Dependent Claim
32 words
A servo control system according to claim 7 or claim 8, wherein the gain change circuit (33b) changes an amplification factor of the first amplifier circuit in response to a state change.
Claim 11
Dependent Claim
40 words
A servo control system according to claim 7 or claim 8, wherein the gain change circuit (33b) changes a differential coefficient of the differential circuit and an amplification factor of the first amplifier circuit in response to a state change.
Claim 12
Dependent Claim
31 words
A servo control system according to claim 7 or claim 8, wherein the gain change circuit changes an amplification factor of the second amplifier circuit in response to a state change.
Claim 13
Dependent Claim
120 words
A disc control system according to any of the preceding claims, wherein the controlled system comprises a head control unit including a head (12) to be position controlled and a motor (13) for driving the head, wherein the speed control means controls the speed of the head (12) through the motor (13) so as to move and position the head to a target track position; and wherein the position control means (3) controls the position of the head (12) through the motor (13) by using a servo signal sensed by the head to position the head to the target track position, after the speed control means (2) has moved the head to a position adjacent to the target track position.
Claim 14
Dependent Claim
172 words
A disc control system according to claim 12, when dependent on claim 2, wherein the master control means (4) is adapted to energise the switching means (5) to connect the head control unit (13) and the speed control means (2) upon receipt of a seek command and the target track position, to issue a moving value between the target track position and the current position of the head to the speed control means, the moving value being used for generating a speed reference, to issue a gain change signal for selecting the first differential gain of the position control means, to deenergise the switching means (5) to connect the head control unit (13) and the position control means (3) when the head reaches a position adjacent to the target track position, to output a seek completion signal when the head is positioned in a predetermined positioning range, and to output another gain change signal for selecting the second differential gain of the position control means (3) after elapse of a certain time.
Claim 15
Dependent Claim
20 words
A disc control system according to claim 12 or claim 13, comprising a magnetic disc system including a magnetic head.
Claim 16
Dependent Claim
16 words
A disc control system according to claim 12 or claim 13, comprising an optical disc system.
References Cited (Backward Citations)
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