Event-Based Control of Mobile Objects over an Unreliable Network

This paper extends an event-based method for the cooperative control of two mobile objects to cope with unknown signal delays induced by the communication network and the computation times of the controllers. The objects are locally controlled and move autonomously along their planned trajectories. The first object called the stand-on object can freely change its trajectory at any time. The second object named the give-way object has to adapt its trajectory to avoid collisions by invoking communication at event time instants. It is provided with an event-based control unit introduced in a previous paper. Whereas the signal delays were neglected in earlier publications, in this paper these delays are considered and the event generation is improved accordingly. An event-based delay estimator generates an estimate of the signal delays, which is utilised for the event generation by using a two-state Markov model that represents the properties of the network. The event-based approach is derived by combining methods from communication technology and control theory. A simulation study with two quadrotors shows the benefits of the method.