Parallel guidance and event-triggered robust fuzzy control for path following of autonomous wing-sailed catamaran

This paper addresses the path following of the autonomous wing-sailed catamaran from two aspects, i.e. guidance and control. Through the real-time access to weather information and kinestates, we develop a parallel guidance algorithm for the sailboat, which comprises two modes, namely tracking of waypoints and course keeping along the reference path. In the first mode, the characteristic tacking and gybing maneuvers of the sailboat are addressed by setting lanes. In the second mode, the Serret-Frenet frame is established to acquire the desired heading angle, and the line-of-sight (LOS) based modification mechanism is designed to prevent the large deviation from the reference path. The proposed guidance is acceptable to the parameterized smooth reference path with arbitrary shapes. In coherence with the guidance, we further design a practical control scheme for the wing-sailed catamaran. With the fuzzy logic systems (FLSs) accounting for uncertainties, the robust damping technique is adopted to reduce the algorithmic complexity. The saturation nonlinearities of actuators are approximated by the sigmoid functions, such that the backstepping approach can be applied. To circumvent the frequent acting of actuators, the ideology of event-triggered control (ETC) is introduced in the control scheme, and the separate triggering conditions are designed for the wing and the rudder respectively, The proposed control scheme can ensure all the errors in the closed-loop system to be semi-global uniformly ultimate bounded (SGUUB). Besides, the existence of minimum inter-event times is proven. Finally, numerical experiments are conducted to verify the feasibility of the proposed scheme.