New study of controller design for networked control systems

Recently there is a great research interest in networked control systems (NCSs). The intended contributions of this study, in the order of they are presented, are (a) to point out a major limitation of current studies on NCSs: many theoretical results - although important and have some significant technical merit cannot be applied to distributed control systems and therefore have little application value; (b) in contrast to that simple numerical examples - often linear systems - are widely used to demonstrate some theoretical results. The authors study the NCS controller design for a non-linear unstable system, which has been historically used for the study of large-scale system control; (c) application of a new design approach: it is suggested that the NCS controller design problem, where data packet time delay, loss or out-of-order need to be addressed, is equivalent to a design problem where the system is point-to-point connected but has delayed and unreliable measurement subsystems; (d) a theorem for the asymptotic stability of a class of non-linear time-delay systems and (e) the stability theorem and the proposed new design approach are applied to the controller design for a model of a network-connected non-linear unstable system stated in (b). Extensive simulation results presented here have demonstrated the effectiveness of the proposed new design approach and the stability theorem