Abstract:

This paper develops further the network reference governor, which is a predictive algorithm for modifying commands sent to the remote system to satisfy state and control constraints. Due to the network communication, the governor must account for a delay that can be time-varying and unknown. The paper summarizes the results on network reference governor theory, and demonstrate its operation on a case study of a attitude control of a spacecraft with a very flexible appendage, where the commands are transmitted remotely over a network to the spacecraft, and hence delayed by a bounded, unknown delay. In this case study, the reference governor ensures that the elastic deflections of the appendage and the control signal satisfy the imposed limits while the spacecraft performs a reorientation maneuver. The paper then presents the novel theoretical construction of a less conservative network reference governor for the case when the delay is long but only slowly time-varying, with known bounds on the rate of change. A spacecraft relative motion control example with constraints on thrust and Line Of Sight (LoS) cone positioning is considered to illustrate these theoretical developments.