H∞ control of networked control systems with time delay and packet disordering

The article is concerned with the design of H∞ controller for networked control systems (NCSs) with both time delay and packet disordering. Analyzing and establishing the relation between time delay and packet disordering, the NCS with both time delay and packet disordering is transformed into the model with multi-step time delays. Given the time delays, we can easily obtain the action time of the control signals without calculating the disorder number. Moreover, a new notion of effective value of transmission packets (EVTP) is proposed in this paper to better study the phenomenon of packet disordering. The bigger the EVTP, the better the NCS will be stabilized, that is, the less negative influence is resulted from packet disordering. By Lyapunov functional method and linear matrix inequality approach, a sufficient criterion for robust stability of NCSs is presented. Finally, numerical examples and simulations are used to illustrate the effectiveness and validity of the proposed method.