Swarm control of USVs based on adaptive backstepping combined with sliding mode Hu Jianzhang，Tang Guoyuan，Wang Jianjun，

Hu Jianzhang，Tang Guoyuan*，Wang Jianjun，Xie De School of Naval Architecture and Ocean Engineering，Huazhong University of Science and Technology， Wuhan 430074，China Abstract：［Objectives］ In view of the problem about the control of the swarm system composed of several underactuated Unmanned Surface Vehicles（USVs），the control strategy of virtual structure method is studied. ［Methods］ In this paper，the problem about the swarm control was transformed into a problem about the stabilization of the position tracking error between the USVs and the virtual structure. The formation transformation of USV swarm was realized based on the changed geometry of the virtual structure. The design of the swarm controller was divided into two parts，i.e. kinematics and dynamics. With adequate consideration of the uncertainty disturbance，the underactuated USV swarm controller was proposed based on adaptive backstepping techniques combined with the sliding-mode control method. The stability of the closed loop system was demonstrated by the Lyapunov theory. The simulation test of straight and curve course running and swarm formation transformation were carried out.［Results］The simulation results show that the synergy of the USV swarm is remarkable，the formation transformation is smooth，and the UAV swarm can adapt to various uncertain disturbances. ［Conclusions］ The swarm system shows strong robustness and flexibility which lays a theoretical foundation for subsequent USV swarm tests. Key words：swarm control underactuated USV； virtual structure； self-adaption； backstepping； ； sliding-mode control