[Objective]This paper investigates the synchronization control problem for supply and supplied ships during underway replenishment in a constantly time-varying ocean environment while considering the ocean environmental disturbances induced by wind,waves and currents,and the interaction effects between ships and their soft connections.It then proposes an event-triggered synchronization anti-disturbance control method based on disturbance estimation and compensation.[Method]The first-order Markov process is used to describe the ocean environmental disturbances induced by waves,wind and currents that affect the sup-ply ship,as well as the unmodeled dynamics.The interaction effects between the ships and their soft connec-tions are included in the unmodeled dynamics.The online disturbance observer estimates time-varying un-known bounded disturbances which are compensated for in the control design using disturbance estimates.The auxiliary dynamic system helps to reduce the control saturation effects on anti-disturbance control.The event-triggered mechanism reduces the execution frequencies of control signals to avoid the excessive wear of the thrusters.[Results]A simulation of a supply ship using the event-triggered control method shows the exist-ence of a minimum sampling interval greater than 0 and the inability to trigger infinitely in a finite time.The controller can achieve synchronous navigation between supply and supplied ships while ensuring the global uniform ultimate boundedness of all closed-loop control signals.[Conclusion]The simulation results valid-ate the effectiveness of the proposed event-triggered disturbance estimation and compensation control method.
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