Anomaly detection method and motor control device

• US 7,439,693 B2
• Filed: 06/29/2005
• Issued: 10/21/2008
• Est. Priority Date: 06/29/2004
• Status: Active Grant

• Current Assignee: THK Company Limited
• Original Assignee: THK Company Limited
• Inventors: Shoda, Kazuo, Nomura, Yuki, Nagato, Yoshifumi
• Primary Examiner(s): Masih; Karen
• Application Number:
  US11/631,005
• Publication Number:
  US 20070188117A1
• Time in Patent Office: 1,210 Days
• Field of Search: 318/135, 318/71, 318/560, 318/568.22, 318/611, 318/616, 318/650, 318/254, 318/138, 318/439, 318/715, 318/798, 318/802, 318/717
• US Class Current: 318/135
• CPC Class Codes: H02H 7/0856 characterised by the protection measure taken
• CPC Class Codes: H02P 25/06 Linear motors

Abstract

A control unit of a motor driver performs feedback control to supply current to a linear motor based on a detection value of a linear encoder. An anomaly detection unit monitors the supply current to the linear motor, and the anomaly detection unit detects anomaly of a linear motion apparatus based on a waveform of the supply current. In the case where the anomaly is detected, a user is notified of warning by means of a lamp, a buzzer, an e-mail, and the like. Therefore, the anomaly of the linear motion apparatus can be detected early and accurately.

Claims

1. A linear motion apparatus anomaly detection method, wherein a motor control device of a motor which drives a movable body of a linear motion apparatus, executes the steps of:

detecting a position or a speed of the movable body;

performing feedback control to supply current or supply voltage to the motor based on the detection result; and

detecting an anomaly of the linear motion apparatus based on an abnormal signal component included in a waveform of the supply current or the supply voltage.

2. A linear motion apparatus anomaly detection method according to claim 1, wherein the motor control device further executes the steps of:

extracting the abnormal signal component which is superposed on a normal signal from the waveform of the supply current or supply voltage; and

judging that the anomaly is generated in the linear motion apparatus when the abnormal signal component satisfies a predetermined condition.

5. A linear motion apparatus anomaly detection method according to claim 2, wherein the extracted abnormal signal component is a high-frequency component of the waveform of the supply current or supply voltage.

3. A motor control device that controls a motor for driving a movable body of a linear motion apparatus, the motor control device comprising:

position detection means for detecting a position or a speed of the movable body;

control means for performing feedback control to supply current or supply voltage to the motor based on the result detected by the position detection means;

anomaly detection means for detecting an anomaly of the linear motion apparatus based on an abnormal signal component included in a waveform of the supply current or supply voltage.

4. A motor control device according to claim 3, wherein the anomaly detection means includes:

a sensor that performs waveform input of the supply current or supply voltage;

a filter circuit that extracts the abnormal signal component from the inputted waveform; and

a comparison circuit that compares the extracted abnormal signal component and a predetermined condition.

6. A motor control device according to claim 3, further comprising extracting means for extracting the abnormal signal component which is superposed on a normal signal from the waveform of the supply current or supply voltage, wherein the anomaly detection means detects the anomaly in the linear motion apparatus when the abnormal signal component satisfies a predetermined condition.

7. A motor control device according to claim 4, wherein the filter circuit extracts a high-frequency component of the wave form of the supply current or supply voltage as the abnormal signal component.