Study of the stability with long time delay in networked control systems

This paper analyses the characteristics of network delay in Internet-based networked control systems by experiments firstly. As for the location of the controller in Internet-based networked control systems is variable, so it will worsen system performance or arouse system unstable. For solving the problem, a kind of networked controller with adaptive active varying sampling period is proposed in this paper. A math model of varying sampling period networked system with long delay is built. Then by means of Lyapunov functional approach, sufficient condition of stability is given. The experiments with networked inverted-pendulum shown that the new networked controller with adaptive active varying sampling period is better than controller with fixed sampling period and parameters.