Model-Based Control of Travelling Wave Type Ultrasonic Motors

Abstract. This paper gives a review of research activities at the Institute for Power Electronics and Electrical Drives in Paderborn to the control of rotary travelling wave type ultrasonic motors. Based on a special designed hardware environment an advanced control scheme for inverter-fed travelling wave type ultrasonic motors is presented. After several modelling steps, including an averaged model for the controller design, a speed control scheme is implemented on a prototype drive. It is realized as an outer control loop of an underlaid voltage and travelling bending wave vector controller. The novel speed control is using an inverse contact model by a neural network, in order to compensate the nonlinear torque generation of the motor. The so equipped ultrasonic motor-drive meets requirements for applications in the field of servo-drives e.g. robotics. Since the reference values of the bending wave control are calculated from the desired torque value by the neural network, open loop control of the drive ́s torque is feasible, too.