Discrete-Time Sliding Mode Controller for NCS Having Random Type Fractional Delay and Single Packet Loss

Abstract

In Networked Control System, the behaviour of network delays generally depends on the characteristics of communication medium as well as occupancy of channel by different elements. When large number of sensors, controllers and actuators share their information through the common communication medium, then the network delays and packet losses are random in nature. In this chapter, a novel approach is presented for designing discrete-time sliding mode controller by treating random fractional delay and packet loss separately. The fractional delay that occurs within sampling period while transmitted from sensor to controller and controller to actuator channel is modelled using Poisson’s distribution function and is approximated using Thiran’s delay approximation technique for designing the discrete-time sliding mode controller. The packet loss that occurs in communication channel between sensor to controller and controller to actuator is treated with Bernoulli’s distribution function and compensated at controller end as well as actuator end. Further, Lyapunov approach is used to determine the stability of closed-loop NCSs with proposed discrete-time SMC controller. The feasibility and efficiency of the proposed control methodology is outlined through simulation and experimental results which shows a significant response even in the presence of random fractional delay, packets loss and matched uncertainties.