Feedforward control method for servomotors

Abstract

A feedforward control method having an improved follow-up characteristic with respect to commands in a servo system and capable of a servomotor to operate smoothly and stably, is applied to a servo system in which a position/speed loop process is executed a plurality of times within one move command distribution period of an upper-level control device. A provisional speed command, which is the product of a gain (Kp) and a deviation (e) between an actual amount (Pf) of rotation of the motor and a move command (a) for each position and speed loop processing period, is corrected by a position feedforward quantity, which is the product of a coefficient (.alpha.1) and a mean value of move commands including the move command for each processing period and those before and after the present processing period calculated by a smoothing circuit to obtain a speed command. A provisional torque command obtained in a speed loop having an integral term and a proportional term is corrected by a speed feedforward quantity, which is the product of a coefficient (.alpha.2) and a differential value obtained by subjecting the mean value of the move commands to a lead compensation in a lead compensation element by a time period equal to a predetermined number of times the processing period to obtain a torque command for driving a servomotor.

Dependencies are inferred from the claim text.