Path Following of Autonomous Underactuated Ships: A Translation–Rotation Cascade Control Approach

In this paper, a novel translation-rotation cascade control (TRCC) scheme is developed for path following of an autonomous underactuated ship suffering from unknown sideslip and complex disturbances. Salient contributions are as follows: 1) finite-time observers are devised to exactly estimate lumped unknowns including sideslip, disturbances, and virtual yaw acceleration; 2) complex unknowns are compositely compensated with finite-time convergence such that exact path following with accurate unknown rejection is achieved; 3) in lieu of detached guidance-control design in previous works, the TRCC facilitates integrated guidance-control (IGC) system in a cascade manner; 4) combining cascade analysis with Lyapunov approach, the entire IGC system is ensured to be globally uniformly asymptotically stable. Both simulation and experimental results are provided to validate the superiority of the proposed TRCC scheme.