AUTOMATIC CONTROL DEVICE

• US 20170212497A1
• Filed: 09/29/2014
• Published: 07/27/2017
• Est. Priority Date: 09/29/2014
• Status: Active Grant

• Current Assignee: Fuji Company Limited
• Original Assignee: Fuji Machine Manufacturing Company Limited
• Inventors: KUMAZAWA, Hideyuki, MIZUNO, Mitsuhiro
• Granted Patent: US 10,345,787 B2
• Time in Patent Office: Days
• CPC Class Codes: G05B 11/32 with inputs from more than one sensing element; with outputs to more than one correcting element
• CPC Class Codes: G05B 19/05 Programmable logic controllers, e.g. simulating logic interconnections of signals according to ladder diagrams or function charts
• CPC Class Codes: G05B 19/406 characterised by monitoring or safety G05B19/19 takes precedence
• CPC Class Codes: G05B 2219/41025 Detect oscillation, unstability of servo and change gain to stabilize again
• CPC Class Codes: G05B 2219/41116 Compensation for instability
• CPC Class Codes: G05B 2219/41423 Noise filter as function of rate of displacement, speed, for stabilisation

Abstract

Automatic control device controls servo motor. Automatic control device is provided with control section that calculates operation amount of servo motor based on the difference between current value and target value of a control amount of servo motor. Automatic control device is also provided with first filter that outputs first output value after using a first filter coefficient or a second filter coefficient to perform filtering of operation amount calculated by control section. Automatic control device is also provided with second filter, arranged in parallel with first filter, that outputs second output value after using a third filter coefficient to perform filtering of operation amount calculated by control section. Automatic control device is also provided with switching section that switches between first output value of first filter and second output value of second filter and sends one of the output values to servo motor.

Claims

1. An automatic control device for controlling a control target, comprising:

a control section that calculates an operation amount of the control target based on a difference between a current value and a target value of the control amount of the control target;

a first filter that outputs a first output value after using a specified filter coefficient to perform filtering of the operation amount calculated by the control section,

a second filter, arranged in parallel with the first filter, that outputs a second output value after using a specified filter coefficient different to the filter coefficient of the first filter to perform filtering of the operation amount calculated by the control section; and

a switching section that switches to and from the first output value of the first filter and the second output value of the second filter and sends one of the output values to the control target.

2. The automatic control device according to claim 1, wherein,

a first filter coefficient or a second coefficient may be input to the first filter,

a third filter coefficient may be input to the second filter, and

a time constant of the first output value of the first filter when the first filter coefficient or the second filter coefficient is input to the first filter is larger than a time constant of the second output value of the second filter when the third filter coefficient is input to the second filter.

3. The automatic control device according to claim 2, wherein

in a case in which the filter coefficient input to the first filter is switched from the first filter coefficient to the second filter coefficient, or switched from second filter coefficient to the first filter coefficient, in a state with the first output value of the first filter being sent to the control target, the switching section switches to a state in which the second output value of the second filter is being sent to the control target before switching the filter coefficient of the first filter and switches to a state in which the first output value of the first filter is being sent to the control target after the filter coefficient to be input has been switched to the first filter.

4. The automatic control device according to claim 3, wherein

the switching section decides the timing of switching from a state in which the second output value of the second filter is being sent to the control target to a state in which the first output value of the first filter is being sent to the control target based on the change of the first output value of the first filter measured during the state in which the second output value of the second filter is being sent to the control target.

5. The automatic control device according to claim 1, wherein the control target is a servo motor.