Cooperative trajectory tracking control of MUSVs with periodic relative threshold event-triggered mechanism and safe distance

This paper addresses the problem of cooperative trajectory tracking control problem for multiple unmanned surface vehicles (MUSVs) with event-triggered mechanism and safe distance, proposes a novel event-triggered adaptive sliding mode control strategy via nonlinear tracking differentiators (NTD) and periodic relative threshold event-triggered mechanism (PRTETM). Firstly, the formation autonomous navigation system is constructed by multiple leader–follower cooperative structure to establish via the synchronization scheme that guarantee the safe distance each others. Next, a novel adaptive sliding mode control with the square root form of position error is introduced to prevent the oscillation or divergence of the system caused by the larger position error. Then, a concise adaptive control strategy to compensate for dynamic model uncertainties and external environmental disturbances. Meanwhile, the NTD is used to quickly track the differential signal and achieve filter performance. Besides, to obtain smaller update frequency and less energy consumption, the PRTETM without Zero behavior and input saturation are introduced to facilitate the triggering of control inputs and avoid the actuator physical constraints. Theoretical analysis proves that the proposed cooperative control system is uniformly ultimately bounded. Finally, numerical simulations and comparisons consolidate that the effectiveness of the above control scheme and superior in the fixed threshold scheme.