Fixed-Time Formation Tracking for Heterogeneous Multiagent Systems Under Actuator Faults and Directed Topologies

This article investigates the problem of fixed-time formation tracking control for a heterogeneous multiagent system composed of unmanned aerial vehicles and unmanned ground vehicles in the presence of actuator faults, model uncertainties, and external disturbances. First, two fixed-time distributed observers are proposed, one of which is applied to detail-balanced directed graph and the other is applied to general directed graph. These two observers remove the requirements of global information and control signal of leader, as well as reduce communication flow. Second, a fixed-time disturbance observer is designed for each follower to estimate lumped uncertainties. Third, a Lyapunov-based formation controller is proposed to guarantee that the fixed-time synchronized formation is achieved for heterogeneous multiagent systems using estimation and backstepping technique. Furthermore, the obtained upper bound of convergence time only depends on the observer gains and controller parameters, which facilitates the adjustment of the settling time offline regardless of initial conditions under different formation requirements. Finally, the effectiveness of the proposed fixed-time protocol is verified using numerical simulations.