SERVO MOTOR CONTROLLING METHOD

• US 20080012520A1
• Filed: 03/23/2007
• Published: 01/17/2008
• Est. Priority Date: 03/24/2006
• Status: Active Grant

• Current Assignee: Toshiba Kikai Kabushiki Kaisha (Toshiba Machine Company Limited)
• Original Assignee: Toshiba Kikai Kabushiki Kaisha (Toshiba Machine Company Limited)
• Inventors: Fujita, Jun, Matsumoto, Ichiro, Hamamura, Minoru
• Granted Patent: US 7,659,682 B2
• Time in Patent Office: Days
• US Class Current: 318/630
• CPC Class Codes: G05B 19/41 characterised by interpolation, e.g. the computation of intermediate points between programmed end points to define the path to be followed and the rate of travel along that path G05B19/25, G05B19/31, G05B19/37, G05B19/39, G05B19/40 take precedence
• CPC Class Codes: H02P 23/06 Controlling the motor in four quadrants

Abstract

A servo motor controlling method includes: directly or indirectly detecting a position of a moving body which performs a circular-arc interpolation feeding motion by a servo motor; performing a feedback control for enabling the position of the moving body to comply with a position command; and at a quadrant changing time when a moving direction of the moving body is changed, performing torque correction on a torque command value according to a distance from a position where the moving direction is changed. By this method, a quadrant protrusion and a torque change with respect to a friction caused from a free zone at a time of reversion of a ball screw can be appropriately corrected. Especially, by performing a first torque correction for a static friction at the position where the moving direction is changed, and by performing a second torque correction for a moving friction after movement by the distance corresponding to the free zone, more appropriate correction can be obtained.

Claims

1. A servo motor controlling method comprising;

directly or indirectly detecting a position of a moving body which performs a circular-arc interpolation feeding motion by a servo motor; and

performing a feedback control for enabling the position of the moving body to comply with a position command;

wherein at a quadrant changing time when a moving direction of the moving body is changed, performing torque correction on a torque command value according to a distance from a position where the moving direction is changed.

2. The servo motor controlling method according to claim 1, wherein the torque correction for a static friction is performed at the position where the moving direction is changed.

3. The servo motor controlling method according to claim 2, wherein the torque correction for the static friction is applied in a forms of a one-time pulse.

4. The servo motor controlling method according to claim 1, wherein the torque correction is not performed within a distance corresponding to a free zone from the position where the moving direction is change.

5. The servo motor controlling method according to claim 4, wherein the torque correction for a moving friction is performed after movement by the distance corresponding to the free zone.

6. The servo motor controlling method according to claim 5, wherein, the torque correction amount for the moving friction decreases in time.

7. The servo motor controlling method according to claim 1,

wherein the moving body has no free zone, and the torque correction for a moving friction is performed according to the distance from the position where the moving direction is changed.

8. The servo motor controlling method according to claim 7, wherein the torque correction amount for the moving friction decreases in time.

9. A servo motor controlling method comprising:

directly or indirectly detecting a position of a moving body which performs a circular-arc interpolation feeding motion by a servo motor; and

performing a feedback control for enabling the position of the moving body to comply with a position command;

wherein a first torque correction for a static friction is performed at the position where the moving direction is changed, and a second torque correction for a moving friction after movement by the distance corresponding to the free zone.