A Cascaded Heading Control Design With Motion Constraint Handling for Marine Surface Vessels

Maritime motion control systems traditionally employ proportional-integral-derivative (PID) feedback control combined with a model-based feedforward structure for heading control. However, such control designs often suffer from the widely accepted limitation that the transient response from disturbances or significant measurement steps will not comply with operational motion constraints. This can pose a risk to onboard passengers and cargo, as the control law can impose motions that violate safety regulations. To address this limitation, we present a novel and simple control design that improves constraint handling while providing feasible rejection of external disturbances. Our design is based on a cascaded structure consisting of an outer-loop heading control law and an inner-loop rate-of-turn control law. The main contribution is the nonlinear feedback design of the outer-loop control law, which uses dynamic augmentation of the heading kinematics and nested saturation functions applied to the resulting second-order kinematics. We prove that the design is input-to-state stable with respect to the rate-of-turn error. The design has similar complexity as traditional designs with respect to implementation and tuning. The feasibility of the design is showcased with a simulation case study. The results demonstrate that the control design effectively handles operational constraints while maintaining good performance. The design has significant potential for real-world application in maritime motion control systems, as it provides a simple yet effective way to ensure compliance with operational constraints on heading rate and acceleration.