On-line relay identification, assessment and tuning of PID controller

In this paper, we present an approach using relay feedback for automatic identification of the PID configuration and parameters in existing and operational closed-loop systems. During the duration of the same experiment, the control performance may be evaluated, providing an assessment of whether the current control parameter set is adequate and if re-tuning is necessary. Systematic and on-line automatic PID tuning rules are further developed and provided for common configurations of PID control. Simulation examples and a real-time experiment are provided to illustrate the practical appeal of the proposed method.