Event-Triggered Sliding Mode Control Strategies for a Class of Nonlinear Uncertain Systems

This chapter presents novel Sliding Mode Control (SMC) strategies of Event-Triggered (ET) type for a class of nonlinear systems affected by uncertainties and external disturbances. By virtue of its ET nature, the proposed control strategies are particularly appropriate for Networked Control Systems (NCSs), i.e., feedback systems including communication networks. The objective of the proposed control schemes is indeed to reduce the number of data transmissions over the communication network, in order to avoid problems typically due to the network congestion such as jitter and packet loss. In particular, an ET-SMC scheme and an ET Second Order SMC (ET-SOSMC) scheme are designed for a class of nonlinear uncertain NCSs, guaranteeing satisfactory performance of the controlled system even in presence of delayed transmissions. The proposed control schemes are theoretically analyzed in this chapter, showing their capability of enforcing the robust ultimate boundedness of the sliding variable associated with the controlled system, and also of its first time derivative in case of ET-SOSMC. Moreover, in order to guarantee the avoidance of the notorious Zeno behaviour, the existence of a lower bound for the time elapsed between consecutive triggering events is proven.