A design method for hybrid event-based control systems

Abstract

This paper investigates control systems, where the controller influences the plant through two control input signals with different characteristics. A continuous control input is used to attenuate disturbances and force the plant to follow a reference trajectory, whereas the operation point of the plant is adjusted by an event-based component of the controller, determining a discrete-valued input signal. Systems of this type are called hybrid event-based control (HEBC) systems. They have typical characteristics of hybrid dynamical systems, because the behaviour of the control loop includes state jumps and switches of the dynamics. In applications, these hybrid phenomena have been neglected and the controllers have been tuned by heuristic rules.To open the way for a systematic control design, this paper clarifies the structure of HEBC systems and introduces a specific model. Based on the model, a design method is proposed for a special class of hybrid event-based controllers, that mimic the behaviour of a purely continuous reference system. The performance of the closed-loop system is investigated by establishing an upper bound on the deviation between the closed loop and the continuous reference system. An application example illustrates the design method and the behaviour of hybrid event-based control loops.