Estimation based approximating control for wireless networked control systems

The control design and system analysis of wireless networked control systems with unknown round-trip delay characteristics are investigated. An estimation based approximating control strategy is proposed to stabilize the systems by using delay characteristics in a practically feasible way. The strategy first uses a delay transition probability estimator to obtain the delay characteristics estimation by measuring delay data online, and then uses an approximating controller to take advantage of the estimation. On this basis, a packet delay variation detector is designed, making the strategy adaptive to the variation of delay characteristics. The sufficient conditions to ensure the closed-loop system being mean-square uniformly ultimately bounded are given, with also the controller gain design method. The effectiveness of the proposed approach is verified numerically.