Optimal-tuning PID controller design for a rotary hydraulic system

A new PID controller design scheme which uses optimisation in the frequency domain is proposed for industrial process control. The optimal PID controller is designed to satisfy a set of frequency-domain performance requirements: gain margin, phase margin, crossover frequency and steady-state error. Using an estimated process frequency response, the method can provide optimal PID parameters even in the case where the process dynamics are time variant. This scheme is demonstrated through its application to a rotary hydraulic system.