Compensation of time-varying delay acting in networked control systems using adaptive Smith predictor and parallel fuzzy-PI controller

Abstract

This paper focuses on problems which arise from network controlled systems within master-slave type of Communications. Since the master and slave are connected over the network, network-induced time-varying delay has negative impact on system stability and control system performance. In order to compensate an influence of delay in NCS we proposed the improvement of two control strategies, Smith predictive and parallel fuzzy-PI controllers. Design of parallel fuzzy-PI controller has no demands for mathematical model of controlled system. Parameters of PI controller are adjusted adaptively depending on the delay. Adaptive Smith predictor is based on the adaptive loop that decreases influence of network-induced delay. It requires a mathematical model of the controlled system. Furthermore, simulations and practical experiments are given to illustrate the effectiveness and robustness of the proposed methods.