Robust PID controller and its application

PID controllers have been widely used in many industrial processes because they have only three control parameters, and we can easily understand their physical meanings. However, it is difficult to tune their parameters in the case where the control system has uncertainties, for example, modeling errors, system fluctuation, and so on. Therefore, we propose a design scheme of robust PID controllers. First, we design a PID controller based on the generalized minimum variance control (GMVC) scheme which is a self-tuning control strategy. Next, we present a method for the design of a weighting factor included in the cost function of GMVC from the viewpoint of robust stabilities. Finally, we discuss the application for an experimental air pressure control system