Variable Gain PID Control of Ultrasonic Motor using Novel Hybrid PSO with Improved Searching Ability

The ultrasonic motor (USM) is a type of actuator driven by frictional force. At present, because of their excellent features, USMs are used in a range of applications, such as for autofocus of cameras and in actuators for devices in MRI environments and microrobots. However, because the dynamic characteristics of USMs vary according to temperature, humidity, and load conditions, their mathematical modeling is difficult. Thus, PID control has conventionally been used for the control of USMs. However, conventional PID control with fixed gains cannot compensate for the non-linear characteristic variation of a USM. In this research, we propose a novel hybrid particle swarm optimization (PSO) system for USM control. The proposed method uses PSO to automatically tune the optimized PID gains. The experiments demonstrated that optimized gains in USM control can be obtained in real time, and high accuracy.