Rate limited reference governor for network controlled systems

Controllers that communicate with sensors and actuators via networks are becoming increasingly common. The networks introduce flexibility, reconfigurability, and simplify maintenance and design, but may degrade the closed-loop performance, due to phenomena such as delays and data losses. These may result in loss of stability and constraints violation. In this paper we propose a control architecture based on reference governor for dealing with network-induced time-varying delays. By modelling the closed-loop as a sampled-data system, the effect of the delay results in an input-variation dependent disturbance, so that the time delay acts as a limit on the rate of change of the command. For the case of delay smaller than the sampling period, control strategies are proposed for full and partial state measurement cases, guaranteeing robust constraints satisfaction and convergence to the setpoint. The results are used for the case where longer than sampling period (and possibly unbounded) delays occur, and a strategy that guarantees convergence using probabilistic arguments is derived.