Robust PI-PD controller design for integrating and unstable processes

Use of integral performance criteria for controller design is a well-known practice. In this work, integral of the squared error (ISE) criterion is modified, and a new objective function is proposed for controller design. The proposed objective function results in maximum sensitivity less than two which implies robust closed-loop performance. Further, a PI-PD control structure is chosen for controlling integrating and unstable processes. Optimal tuning rules are obtained by minimizing the proposed objective function with the use of Particle Swarm Optimization. Simulation results show that the proposed tuning rules exhibit improved closed-loop performance with satisfactory robustness when compared with the recent tuning strategies. Hardware validation on magnetic levitation experimental setup is also performed.