Multivariable gain scheduled control of four tanks system: Single scheduling variable approach

Abstract

Motivated by the special class of nonlinear systems, we introduce a scheduling technique that aims at extending the region of validity of linearization by designing an extra scheduling mechanism. Specifically, we show, how a simplification of a control problem may results in a considerably difficult scheduling procedure. In particular, the scheduling problem in the context of a nonlinear model of four tanks is addressed. The main innovation consists in the use of auxiliary scheduling variables dealing with the problem of limited number of output variables. This allows to construct a linear feedback controller at each operating point. Additionally, an integral control which ensures desired stability and performance requirements is presented. The resulting method has been integrated into the gain scheduled control design of the four tanks system and has shown a great performance through the operating range. © Springer International Publishing Switzerland 2016.