Research On Parameter-tuning Of PID Controllers With Bacterial Foraging Optimization Algorithm

PID controllers are by far the most popular in process control. With the development of the computer technology and the industrial manufactures, the traditional parameter-tuning methods can not easily get the satisfactory performance for non-linear, multi-dimensional and uncertain complex industrial processes. It is one of the effective methods to introduce intelligent optimization methods to design control systems.Recently, bacterial foraging optimization (BFO) algorithm comes forth as a new evolutionary computation intelligent technique. It is simple with the algorithm fast convergence, requiring few priori knowledge. The optimal parameter-tuning of PID controllers are studied based on BFO algorithm. The main contributions of this thesis are as follows:(1) The integrator plus time delay process is common in the process control. But the optimal tuning of the PID controller for this plant has been a hot issue in the control system design. By combining the bacterial foraging optimization (BFO) algorithm and the strategy of control system optimization design, a novel method was proposed to optimize the parameters of the PID controller. The simulation results show that the optimal PID controller based on BFO is better in set time and robustness than other several PID controllers. The tuning formulas were proposed through a lot of simulation results.(2) It is difficult for a conventional PID controller to get the optimal dynamic performance of responses to both set point and load disturbance. The case is changed when the two-degree-of-freedom (2-DOF) PID controller is used. BFO algorithm can easily figure out the optimum parameters of two-degree-of-freedom (2-DOF) PID controllers. The simulation results show that 2-DOF PID controllers designed by BFO algorithm provides satisfactory performance.(3) Because the BFO algorithm lacks in adaptation according to the operating condition, a fuzzy bacterial foraging optimization algorithm is proposed bycombining BFO with fuzzy logic. Then FBFO algorithm is applied to optimize the PID controller parameters. Simulation results show that satisfactory performance is achieved.