Research ArticlePID controller auto-tuning based on process step response and damping optimum criterion

- FOPDT model may not accurately describe process dynamics for PID controller tuning purposes.
- PID controller tuning is based on PTn process model and damping optimum criterion.
- Proposed tuning method results in straightforward adjustment of closed-loop damping and response speed, also being relatively robust to process parameter variations.
- PTn model on-line identification is based on single integration of process step response.
- Process model identification and related PID controller auto-tuning are verified by extensive simulations.

This paper presents a novel method of PID controller tuning suitable for higher-order aperiodic processes and aimed at step response-based auto-tuning applications. The PID controller tuning is based on the identification of so-called n-th order lag (PTn) process model and application of damping optimum criterion, thus facilitating straightforward algebraic rules for the adjustment of both the closed-loop response speed and damping. The PTn model identification is based on the process step response, wherein the PTn model parameters are evaluated in a novel manner from the process step response equivalent dead-time and lag time constant. The effectiveness of the proposed PTn model parameter estimation procedure and the related damping optimum-based PID controller auto-tuning have been verified by means of extensive computer simulations.