| 摘要 |
A servo controller is capable of preventing downward displacement of a gravitating axis of a machine when an excitation of a servomotor (5) for driving the gravitating axis is discontinued. When a shutdown command is issued, a command for shifting a position of the gravitating axis by an offset amount in a direction opposing the gravitation is issued to a servo system. Also, a command for operating a mechanical brake (8) to apply a braking force on the gravitating axis is issued. After a predetermined time period, the excitation of the servomotor (5) is discontinued. The position of the gravitating axis is shifted upward by the offset amount within a time-lag between an issuance of the mechanical brake operating command and actual application of the braking force by the mechanical brake (8), and the braking force is applied to the gravitating axis at the shifted position. When the excitation of the servomotor (5) is discontinued, the downward displacement of the position of the gravitating axis due to a backlash of the mechanical brake (8) is compensated by the upward shifting of the gravitating axis. Thereby, movable elements connected to the gravitating axis are prevented from collision or interference with peripheral objects. |
