Auto-tuned variable structure control of cleanrooms

This paper presents an approach for modelling and control of a cleanroom en vironment, and in this instance we focus on the cleanroom temperature. A mo dified relay feedback is employed as part of an automatic tuning procedure to introduce controlled perturbations into the closed-loop system. From the ensuing input-output signals, the parameters of a nonlinear physical model can be obtained using the least squares estimation algorithm. A variable s tructure controller is designed based on this model and it is able to ensur e asymptotic tracking of the reference command signals and is robust in the presence of both parametric and non-parametric uncertainties. Simulation e xamples are provided for illustration. (C) 1998 Elsevier Science Ltd. All r ights reserved.