Implement of variable sampling in multi-loop NCS

Abstract

This paper is concerned with realization of variable sampling in multi-loop NCS (Networked Control System) using variable sampling period scheduler. Considering sampling period on the influence of NCS, the strategy of variable sampling period is proposed for multi-loop of NCS. Implement of variable sampling period scheduler is designed according to network utilization and network delay. The method of online measurement of network delay is introduced. OPC technique is applied to transmit network delay, which will be used to realize prediction of network delay. Robust Kalman filter is applied to predict network delay of next period. The sampling period of next period is calculated according to the predicted value of network delay and network utilization. Sampling period is distributed to each control loop of NCS based on OPC technique. Finally, the experiment implementation demonstrates the feasibility of the proposed method.