Event-Triggered Discrete Higher-Order SMC for Networked Control System Having Network Irregularities

This article presents a discrete-time higher-order sliding mode controller for networked control system (NCS) using event-triggered approach and time-delay compensation to overcome the network abnormalities such as communication delay, congestion, and network utilization that degrade the performance of the NCS. First, a novel event-triggered sliding variable is constructed with time-delay compensation using Thiran's approximation, followed by discrete-time supertwisting algorithm in which control actions are updated based on the event generation. The event generator block in feedback channel results in an increase of communication rate efficiency and reduction in network congestion. The stability of closed-loop system is addressed using the Lyapunov technique, which guarantees the finite convergence of system states within the designed sliding band. Furthermore, the proposed controller is validated on a laboratory set up of serial flexible joint robotic manipulator. The simulation and experimental results show that the proposed controller outperforms the controller with reaching law approach.