Fuzzy fractional order PID based parallel cascade control system

Parallel cascade controllers are used in process and control industries to improve the dynamic performance of a control system in the presence of disturbances. In the present work, fuzzy set point weighted Fractional Order Proportional Integral Derivative (FOPID) controller is designed for the primary loop of the parallel cascade control system. The secondary controller is designed using the internal model control (IMC) method. Also, a smith predictor based dead time compensator is designed to compensate large time delay in the process. Several case studies are considered to show the advantage of the proposed method when compared to other recently reported methods. The proposed method provides robust control performance which significantly improves the closed loop response with less settling time when compared to conventional PID controller based parallel cascade control system. © Springer International Publishing Switzerland 2014.