US 7,397,628 B2 · Two degree of freedom position control method, two degree of freedom position control device, and medium storage device

Abstract

In a position control device based on a current observer control for performing two degree of freedom control, deterioration of the position accuracy caused by the output delay due to computation is prevented. In the two degree of freedom control system for preventing overrun, the delay of output of the two degree of freedom control (computing delay and hardware delay of drive amplifier, D/A converter, etc.) is considered, and the estimated state of Td which is advanced by the amount of delay from the sample point of time is computed, then output is computed based on this estimated state. So even if state changes during calculation from the sample point of time, the influence of the output delay can be prevented, and highly accurate position control can be performed, therefore overrun can be prevented.

Claims18

Dependent claims

A position control method for controlling a position of an object to a target position by an actuator, comprising:

a step of computing a position error based on a target position of the object and a current position of the object;
a step of correcting an estimated position in a current sample by an estimated position error between said position error and an estimated position in a current sample of a current observer;
a step of computing a difference between the corrected estimated position and a target trajectory in the current sample;
a step of computing an estimated position advanced by a predetermined time from the sample point of time based on an output value in one sample before and the difference;
a step of computing an output value to the actuator based on the advanced estimated position;
and
a step of computing an estimated position for the next output value computation based on the corrected estimated position, the output value in the current sample, and the output value in one sample before.

4 more elements

A medium storage device, comprising:

a head for at least reading data on a storage medium;
an actuator for positioning the head to a predetermined position of the storage medium;
and
a control unit for computing a position error from a target position of the head and a current position acquired from the head, and computing an output value for driving the actuator by a current observer control,
wherein the control unit corrects an estimated position in a current sample by an estimated position error between said position error and an estimated position in a current sample of the current observer, computes a difference between the corrected estimated position and a target trajectory in the current sample, computes an estimated position advanced by a predetermined time from the sample point of time based on an output value in one sample before and the difference, computes the output value to the actuator from the advanced estimated position, and computes an estimated position for the next output value computation based on the corrected estimated position, the output value in the current sample, and the output value in one sample before.

2 more elements

A position control device for controlling a position of an object to a target position by an actuator, comprising:

a block for computing a position error based on a target position of the object and a current position of the object;
and
a current observer for correcting an estimated position in a current sample by an estimated position error between the position error and an estimated position in a current sample, computing a difference between the corrected estimated position and a target trajectory in the current sample, computing an estimated position advanced by a predetermined time from the sample point of time based on an output value in one sample before and the difference, computing an output value to the actuator based on the advanced estimated position, and computing an estimated position for the next output value computation based on the corrected estimated position, the output value in the current sample, and the output value in one sample before.

Dependencies are inferred from the claim text.

Two degree of freedom position control method, two degree of freedom position control device, and medium storage device

Life of this patent

Two degree of freedom position control method, two degree of freedom position control device, and medium storage device

Life of this patent

Abstract

Claims18