Cooperative output tracking of a network of non-minimum phase systems

This paper develops a solution to the cooperative output tracking problem of a network of non-minimum phase (NMP) vehicles under a direct and time-varying communication topology. The desired trajectory is generated by a linear exo-system and accessible to partial vehicles. The solution consists of three modules: a distributed observer network (DON), a causal stable inversion (CSI), and a state trajectory tracker (LSTT), where DON generates an estimate of the desired trajectory for each vehicle and CSI gives a bounded state reference for LSTT. The solution is applicable to a wide range of situations where the vehicles may be homogeneous or heterogenous, minimum phase or NMP. In particular, for a network of N linear heterogenous NMP vehicles, we develop some conditions on the modules, present a specific realization and show the convergence of tracking errors and the boundedness of vehicles' internal states, and finally verify the realization by simulation.