Output Formation Tracking Control for Heterogeneous Multi-Agent Systems with Application to Unmanned Aerial and Ground Vehicles

Distributed output formation tracking control problem for heterogeneous multi-agent systems (HMASs) was studied in this paper. The HMASs include multi-rotor unmanned aerial vehicles (UAVs) and unmanned ground vehicles (UGVs) with nonholonomic constraints. A formation tracking protocol was proposed for the follower UAVs and UGVs to track the virtual leader's output trajectory while keeping a predefined time-varying shape. In this protocol, a distributed observer was first designed for each follower to estimate the states of the leader. Then, a local formation controller based on feedback linearization was designed for UAVs, while a nonlinear controller was presented for UGVs to tackle the nonholonomic constraints. The effectiveness of this protocol was proved by the Lyapunov stability theory. Finally, a cooperative searching experiment with two quadrotors and a wheeled vehicle was performed under the ultra wide band (UWB) positioning system, and the experiment results matched the simulation well.