Driving method of multiple ultrasonic motors using common line signal input

As the demand for multi degrees of freedom (DOF) system increases, it becomes more important for engineers to select an appropriate actuator. An ultrasonic motor is one of the promising actuators for multi-DOF system because of its advantages as direct drivability, high stationary holding torque, noiseless and quick response against input signal, however, the complexity of input wiring could be one of the problems for practical use. So this study proposes a novel driving method for multiple ultrasonic motors using a common line signal input. The method uses a superimposed signal, which has frequency components corresponding to the driving frequency of each ultrasonic motor. Because ultrasonic motors are driven by the natural vibration of stators, each motor only drives according to the corresponding frequency component of the common superimposed signal input. First we confirm the influence of the proposed method on the rotational speed of each ultrasonic motor. Then we controlled the rotational speed of each motor using the proportional controller, which operates the superimposed signal commonly inputted to each motor.