Hybrid strategy for improving PSO and its application for self-tuning PID controller on position control of ultrasonic motor

In this paper, a soft intelligent computation for determining the optimal gains of PID controller of an ultrasonic motor servo system using the modified particle swarm optimization (MPSO) is presented. The proposed method is to improve the performance of PSO by using the combination of two different inertia weight strategies, namely adaptive inertia weight (AIW) and random inertia weight (RIW). This hybrid strategy, we called as APSO-RIW, is introduced, which is motivated by the benefits of the PSO-AIW or APSO and PSO-RIW. It is used as self-tuning scheme of PID controller to overcome the nonlinearity and characteristic changes of ultrasonic motor. Experimental results show that the proposed hybrid strategy can greatly enhance the performance of PSO in term of convergence speed and position accuracy of ultrasonic motor.