Distributed Switching Control to Achieve Almost Sure Safety for Leader-Follower Vehicular Networked Systems

Leader-follower formation control is a widely used distributed control strategy that requires systems to exchange their information over a wireless radio communication network to attain and maintain formations. These wireless networks are often subject to deep fades, where a severe drop in the quality of the communication link occurs. Such deep fades inevitably inject a great deal of stochastic uncertainties into the system, which significantly impact the system's performance and stability, and cause unexpected safety problems in applications like smart transportation systems. Assuming an exponentially bursty channel that varies as a function of the vehicular states, this paper proposes a distributed switching control scheme under which the local controller is reconfigured in response to the changes of channel state, to assure almost sure safety for a chain of leader-follower system. Here almost sure safety means that the likelihood of vehicular states entering a safe region asymptotically goes to one as time goes to infinity. Sufficient conditions are provided for each local vehicle to decide which controller is placed in the feedback loop to assure almost sure safety in the presence of deep fades. Simulation results of a chain of leader-follower formation are used to illustrate the findings.