ROBUST CLOSED LOOP LOG MODULUS DESIGN OF SISO SMITH PREDICTORS FOR A SPECIAL CLASS OF PROCESSES

Abstract

Linear open loop stable or prestabilized SISO processes with uncertain or changing time delays are controlled via a Smith Predictor. The processes under consideration have no other nonminimum phase characteristics than the time delay. Further, the process models have an inherent integration constant of zero or one. A controller design procedure is presented which guarantees a robust closed loop system, where the major tuning parameter of the controller is a nonlinear function of the maximum closed loop Log Modulus and the model-plant mismatch.

KEYWORDS:

• Process control
• Smith predictor
• Robust tuning
• Dead time systems