A new particle swarm optimization based auto-tuning of PID controller

Particle swarm optimization based auto-tuning of Proportional-Integral-Derivative (PID) controller is discussed in this paper. Relay feedback experiment is applied to identify the approximate parameters of PID controller first, although the parameters identified is not very accurate. Next we utilize particle swarm optimization algorithm to refining parameters of PID controller. The basic particle swarm optimization based auto tuning PID algorithm often fall into local optimum. To improve the performance of controller, an improved PSO method is proposed in this paper by dividing the searching process into two steps. First the parameter k_d of particles is limited in a small space then enlarged to a larger one. Our experiments confirm the method can improve the perform ance of PID controller dramatically.