| 摘要 |
PROBLEM TO BE SOLVED: To decrease the influence of an error between output pulse intervals of an encoder which detects the speed of a servo motor, improve accuracy of speed control by estimated speed, and prevent such a condition as the servo motor continues to stop when a command speed is not 0 in an estimated speed control. SOLUTION: The detected speed of a servo motor 1 is calculated from the output pulse of an encoder 2 by a speed calculating part 4, and estimated load torque is calculated from the detected speed and motor current detected with a current detector 11 by an estimated load torque calculating part 6 each time an output pulse occurs. Average estimated load torque is calculated and updated by averaging the estimated load torque (n) times by a n-time averaging part 12 each time the output pulse occurs. A speed control part 9 makes speed control so that the detected speed may be a command speed in a prescribes control cycle, and if the detected speed cannot be calculated in a zone of the speed control cycle, the estimated speed is calculated from the average estimated load torque and the motor current by an estimated speed calculating part 7, thus making speed control so that the estimated speed may be the command speed. |
