Line-of-Sight Guidance Strategy for Collaborative Berthing of Autonomous Tugs

It is challenging and hazardous for large ships to achieve berthing from open sea to a port. The development of autonomous tugs (ATs) offers a chance to assist large ships in berthing operations via the application of multiple contact-connected ATs. This paper proposes a line-of-sight (LOS) guidance based collaborative control scheme for a multiple AT pushing system to assist berthing subject to intervehicle collision avoidance. In this framework, the dynamic collaborative decision mechanism relies on the relative positions of two adjacent ATs. The controllers for collaborative berthing are developed based on constructing a quadratic programming problem subject to contact force constraint, actuator constraints, and payload constraints caused by large ships. Simulation results demonstrate that the proposed control scheme is able to assist large ships in berthing.