Nonlinear feedback-based event-triggered output-feedback control for marine surface vehicles under deferred output constraints

This paper investigates the trajectory tracking control for marine surface vehicles (MSVs) in the presence of deferred output constraints, unmeasured velocities, model uncertainties, and unknown external disturbances. A dynamic event-triggered extended state observer (DET-ESO) is proposed to achieve real-time estimation for unmeasurable velocities and lumped disturbances with lower communication cost of measurement channels, and an explicit relationship between the upper bounds of estimation errors and design parameters is provided. Based on the observation results, the control design is conducted using the backstepping approach. Initially, a nonlinear feedback method is employed to empower the control scheme to be self-tuning for tracking errors, thereby improving the dynamic performance of the control system. Subsequently, an error-shifting function and a novel barrier Lyapunov function (BLF) suitable for compound features of nonlinear feedback are used to handle deferred output constraints with unknown initial tracking conditions. On this basis, a dynamic event-triggered mechanism, including dynamic variables and decreasing functions of tracking errors, is presented to evaluate control input signals to dramatically reduce the transmission load and actuator execution rate, and the development of the control scheme is accomplished. Theoretical analysis shows that with the proposed control scheme, all signals in the closed-loop system are uniformly ultimately bounded, and the output constraints violated initially are fulfilled within a preset finite time. Additionally, Zeno behavior is excluded strictly. Finally, the comparative simulation results verify the effectiveness of the scheme.