METHOD FOR CLOSED-LOOP MOTION CONTROL OF AN ULTRASONIC MOTOR

摘要

The invention relates to a method for closed-loop motion control of an ultrasonic motor, said ultrasonic motor comprising at least one actuator with a friction means, with at least one excitation electrode and with at least one common electrode, and with the ultrasonic motor further comprising an element to be driven, a controller and at least one electrical generator for generating at least a first excitation voltage U 1 and a second excitation voltage U 2 to be applied to the electrodes of the actuator and thereby generating vibration of the actuator, wherein the friction means of the actuator, due to its vibration, intermittently comes into contact with the element to be driven and thereby generating a driving force on the element to be driven, wherein the method comprises the step of providing said at least two excitation voltages U 1 and U 2 with different frequencies, the frequency of U 1 corresponding to a first resonance frequency of the actuator and the frequency of U 2 corresponding to a second resonance frequency of the actuator and with the frequency difference between U 1 and U 2 deviating from a servo sampling frequency of the controller by 5 kHz at the most, and applying said at least two excitation voltages U 1 and U 2 to the electrodes of the actuator.