Method of controlling a servo motor

Abstract

To control a servo motor, after the sign of a shift command is inverted, a first offset amount Vmo is added to a speed command during a period the motor rotates by the amount of "a" so that inversion of sign of an integral value of the speed loop is made to occur earlier, thereby accelerating the reversal of the direction of the motor. Then, after the motor has rotated by an amount "b", a second offset amount Vto is added to the speed command, thereby causing the motor to generate a torque that is large enough for an object connected to the motor to start moving to overcome the frictional force. The first offset amount is determined based on a value of an integrator in the speed loop at the time the direction of the shift command is inverted so that the servo motor is reversed by the correct amount. The second offset value is reversed determined based on the acceleration at the moment of inversion, so that its value is optimized corresponding to the frictional force. As a result, the delay of motion at the time of reversion is small, and it becomes possible to reduce a protrusion occurring on a cut surface in the transition of machining from one quadrant to another quadrant.

Dependencies are inferred from the claim text.