Auto-tuned variable structure control of cleanrooms

This paper presents an approach for modelling and control of a cleanroom environment, and in this instance we focus on the cleanroom temperature. A modified 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 structure controller is designed based on this model and it is able to ensure asymptotic tracking of the reference command signals and is robust in the presence of both parametric and non-parametric uncertainties. Simulation examples are provided for illustration.