Path-following control of hydrogen-powered unmanned surface vehicles with input-delay constrains

Objectives Aiming at the input delay problem of underactuated unmanned surface vehicles (USVs) powered by hydrogen fuel cells, the study is conducted to propose a feasible path-following control method to improve the control performance of such USVs under input delay constraints. Methods First, the surge-guided line-of-sight (SGLOS) guidance algorithm was introduced to synchronously plan the surge speed and yaw angle at the kinematic level, so as to realize the asymptotic convergence of path-following errors. Second, a second-order auxiliary dynamic system was constructed to transform the USV model with 1-3 s input delay into a delay-free nonlinear dynamic system. Then, the backstepping method combined with coordinate transformation was adopted to design the longitudinal and heading feedback controllers respectively, and the auxiliary system-based path following control (AS-PFC) scheme was constructed. Finally, comparative simulations were carried out on the Cybership Ⅰ platform, in which the SGLOS algorithm was compared with ILOS and ALOS algorithms, and the AS-PFC scheme was compared with the robust path-following control scheme without delay compensation. Results The SGLOS algorithm showed better performance in convergence speed, tracking smoothness and steady-state error than ILOS and ALOS algorithms at the kinematic level. The AS-PFC scheme effectively compensated the 1-3 s input delay, which realized faster and smoother path-following convergence, reduced steady-state error, and generated control inputs with smaller amplitude and smoother variation; the state variables of the auxiliary system converged rapidly, and all signals of the closed-loop system kept uniformly ultimately bounded. Conclusions The SGLOS guidance algorithm can effectively improve the kinematic path-following performance of underactuated USVs. The second-order auxiliary dynamic system can well compensate the input delay caused by hydrogen fuel cell systems, and the designed AS-PFC scheme significantly improves the path-following accuracy, response speed and robustness of hydrogen-powered USVs under input delay constraints, providing an effective technical solution for the path-following control of such USVs.