Robust Stability Analysis of Filtered PI and PID Controllers for IPDT Processes

The paper discusses the stability and robustness of proportional-integral (PI), proportional-integral-derivative (PID), proportional-integral-derivative-accelerative (PIDA) controller for integral-plus-dead-time (IPDT) plants. To enable implementation measurement noise attenuation, binomial low-pass filters are added to traditional design controllers with ideal transfer functions, impact on robust circuit is studied in detail. proposed tuning, which integrates suboptimal filter design, based explicit tuning formulas derived by using multiple real dominant pole (MRDP) method. It shown that combining derivative actions possibly higher-order filters, it possible either accelerate transients or increase closed loop problem defining area should be addressed at stage determining process model. In addition, if wishing maintain unfiltered PI control, while increasing degree components, one needs filtering properties used accordingly. Simple analytical relations setting filtered PI, PID, PIDA equivalent derived.