PID controller tuning based on Smith-type compensator for second-order processes with inverse response and time delay

Processes exhibiting dynamic behaviors of inverse response and time delay make the control system design more difficult. This paper presents the deign concepts and tuning rules for PID controller for processes with inverse response and time delay. The control system design is based on a Smith-type compensator for non-minimum phase dynamics, which aims to remove these elements from the feedback loop. In this control scheme, it is necessary to factorize the process model into minimum phase and non-minimum phase parts. Different factorization methods are thus investigated and compared, and it turns out that the system resulted from direct factorization method can achieve better tradeoff between control performance and system robustness. Then, the equivalent feedback controller for the proposed control configuration is approximated as a classical PID controller by the Maclaurin-series approach. The analytical tuning rule for PID parameters is developed, and the robust stability analysis is provided. Simulation examples demonstrate the superiority of the proposed design method.