Distributed fixed-time sliding mode formation control for unmanned aerial-ground vehicle (UAV-UGV) heterogeneous system

This study proposes a distributed fixed-time sliding mode formation control (FTSMFC) method to address formation control problem for unmanned aerial-ground vehicle (UAV-UGV) heterogeneous system under the directed topology and subject to external disturbances. First, a distributed fixed-time state observer (FTSO) is introduced to provide state estimation of the leader UAV, which overcomes the limitation of partial information availability among followers. Then, a novel fixed-time disturbance observer (FTDO) is presented to enhance the system's anti-disturbance ability by estimating and compensating external disturbances within a fixed time. Furthermore, by integrating sliding mode techniques and the information from the FTSO and FTDO, a distributed FTSMFC is developed to enforce the system to achieve predefined formation configuration within a fixed time independent of initial states of the system. Finally, a simulation comparison with the other controllers is carried out to show the validity and superiority of the proposed formation control law.