Design of Networked Control System with Discrete-Time State Predictor over WSN

Abstract

 Abstract—We design a networked control system (NCS) with discrete-time state predictor where the communication between the controller output and the plant input takes place over a wireless sensor network (WSN). In order to measure time delays between the controller output and the plant input in real time, we design an algorithm to measure round trip time (RTT) between WSN nodes, and implement it into TinyOS of WSN. By using the measured time delays, we construct the discrete-time state predictor to compensate the time delays between the controller output and the plant input in real-time. For the real time experiment, we simulate the dynamic plant model, the controller, and WSN interface using Real-Time Windows Target provided in MATLAB. The WSN interface in the Simulink model consists of serial ports, which connect the controller output and the plant input with WSN nodes. The experiment results show that the time delays between the controller output and the plant input are precisely measured in real time; the discrete-time state predictor appropriately compensates the time delays; and the stability is achieved in the closed-loop of the NCS. In this paper, we design an NCS with discrete-time state predictor where the communication between the controller output and the plant input takes place over WSNs. In order to measure time delays between the controller output and the plant input in real time, we design an algorithm to measure round trip time (RTT) between WSN nodes, and implement it into TinyOS of WSN. By using the measured time delays as a parameter, we construct the discrete-time state predictor (6), (7) to compensate the time delays between the controller output and the plant input in real time. The discrete-time state predictor suitably compensates measured time delays in the feedback loop. The experiment results show that the time delays between the controller output and the plant input are precisely measured in real time; the discrete-time state predictor appropriately compensates the time delays; and the closed-loop of the NCS is made to be stable.