ABSTRACT In this paper, a novel robust adaptive practically predefined‐time‐synchronized tracking control strategy is proposed for the trajectory tracking problem of underactuated surface vessels (SVs) with simultaneous unknown external time‐varying disturbances, unknown model parameters, and input saturation. Firstly, a coordinate transformation is constructed to handle the underactuation issue of the underactuated SVs. Then, a new predefined‐time prescribed performance function (PTPPF) is constructed, which can not only preset the time for the tracking errors to reach the steady‐state error bound, but also reduce the initial value of the control input. Furthermore, the integrated uncertainties caused by unknown external time‐varying disturbances, saturation errors, and the unknown model parameters are transformed into a linear single‐parameterized form. Building on the above, a novel practically predefined time‐synchronized robust adaptive trajectory tracking control law is designed by combining dynamic surface control technology, predefined‐time theory, and PTPPF, in which the adaptive laws online estimate the linearized single parameter and unknown control coefficients. Additionally, novel adaptive leakage terms are designed, which not only realize the predefined time control but also enhance the robustness. Theoretical analysis indicates that the proposed control scheme guarantees that the tracking errors synchronously converge to the preset steady‐state error band within a predefined time, while all closed‐loop signals remain bounded. Simulation results on a CyberShip II demonstrate the effectiveness and the superiority of the proposed control scheme.
Qin et al. (Tue,) studied this question.