Tuning of a robust PID controller-application to heating process inextruder

摘要

In this paper different methods are compared for tuning a robustnPID controller for a heating process in an extruder. These tuningnmethods are internal model control, Clarke method, and Cohen & Coonnmethod. Robustness is needed because the process is nonlinear. By usingnprocess model uncertainty the robust stability theorem is employed tonassure that the feedback loop with the nonlinear process and the linearnPID controller will be stable at all operating points. The modelnuncertainty is approximated with the help of a nonlinear physical model,nwhich is based on heat balance equations. The controller parameters arenselected to satisfy the requirement of the robust stability under modelnuncertainties