Tuning of PID Controller Based on Foraging Strategy for Pneumatic Position Control System*


Abstract:Pneumatic servo system has been applied in many industry fields. The system has many advantages, such as high speed, high flexibility and low price. However, the application of the system is restricted because the physical parameters have strong nonlinearity, inaccuracy and uncertainty, so that it is very difficult to find an optimal controller by means of traditional control theory. Proportional integral derivative (PID) control is one of the earlier control strategies; it has a simple control structure and can be easily tuned. Optimization of PID controller parameters is one of the recent control solutions; especially when the system is of high complexity. In this paper foraging strategy has been adopted to optimize the gains of PID controller for positioning control of a pneumatic system. The foraging theory is based on the assumption that animals search for nutrients in a way that maximize their energy intake per unit time spent for foraging. The bacterial foraging algorithm is a non-gradient and stochastical optimization technique; as no need for measurement and analytical description. In the work, the optimization model of E. coli bacterial foraging has been used and the performance index (cost) is based on Integral Square Error (ISE) for obtaining sub-optimal values of controller parameters. The behavior of bacteria (solutions) over their lifetime has been simulated and the effect of foraging parameters on cost function has been studied.