Decentralized control of nonlinear systems using selftuning controllers

Abstract

This contribution presents a usage of Self-Tuning Controllers Simulink Library (STCSL) for control of the nonlinear systems using decentralized approach. The STCSL was created for design, simulation verification and especially real-time implementation of single-input/single-output (SISO) digital self-tuning controllers (STC). The proposed self-tuning controllers what are included in the library can be divided into three groups. The first group covers self-tuning PID controllers, the second group of described controllers is based on the polynomial approach and the third group contains the controllers derived on the other approaches (minimum variance control etc.). This paper is focused on decentralized control of multi-input/multi-output (MIMO) nonlinear systems in real time applications. The aim is to investigate simple discrete STC with respect to their usage in real-time decentralized control. A supervisory logic block is used in the control scheme to increase the stability of the recursive identification process by ensuring that just one of the controllers is in adaptive mode at a particular time. The logical supervisor is purposed as a simple and reliable technique for designing the supervisory system. The basic idea of the logical supervisor is based on assigning priorities to individual outputs of controlled multivariable system and on-line evaluation of criterions for each subsystem. The usage of this approach has been tested in real-time conditions for control of two-input/two-output (TITO) laboratory models. The STCLS is available free of charge at Internet site -http://www.utb.cz/stctool/.