PID controller design based on second order model approximation by using stability boundary locus fitting

This study presents a model reduction method based on stability boundary locus (SBL) fitting for PID controller design problems. SBL analysis was commonly applied for controller stabilization problems. However, we use SBL analysis for the reduction of high order linear time invariant system models to second-order approximate models to facilitate analytical design of closed loop PID control systems. The PID design is implemented by a multiple pole placement strategy which enforces the control system had real poles with a desired time constant specification. Illustrative design examples are presented for the analytical PID design of high-order plant models by means of second-order SBL model approximations.