Constrained trajectory planning for automatic berthing of maritime autonomous surface ships based on input-to-state safe zeroing high order control barrier functions

This paper addresses the trajectory planning of maritime autonomous surface ships (MASSs) for automatic berthing moving in a restrictive harbor subject to multiple port shorelines. A trajectory planning method is proposed for the automatic berthing of an MASS with collision-free behavior. First, a line-of-sight guidance method is utilized to obtain a sequence of surge velocity, sway velocity, and yaw rate signals such that a nominal trajectory is generated for the MASS to reach the final berthing position with a desired heading angle. Next, a sequence of surge force and sway force signals are generated by using the estimated disturbance information obtained from extend state observer. Then, input-to-state safe zeroing high order control barrier functions (ISSf-ZHOCBFs) are introduced to encode the port shorelines as multiple safety constraints. Finally, the encoded safety constraints are further resorted to formulate a quadratic program problem for obtaining optimized yaw rate, surge force, and sway force signals such that a safety trajectory for automatic berthing is obtained. Simulation results verify that the effectiveness of the proposed ISSf-ZHOCBF-based trajectory planning method for collision-free automatic berthing.