Chase, No Straighter: COLREG Compliant Anti-collision Manoeuvres for Crossing Situations

The interaction between autonomous vessels and humans is a problem which has not clearly been addressed. One solution for this is that autonomous vessels implement rules and algorithms that mimics the behaviour of trained seafarers that acts in accordance with the International Maritime Collision Regulations (COLREGS). We suggest a simple algorithm that ’chases’ the tangent point of the Circle of Rejection that is set outside other vessels. The algorithm utilises the same information that would be used by a human navigator—and it uses this information to guide an autonomous vessel in a way that will satisfy COLREG Rule 8 which requires anti-collision manoeuvres to be positive, timely and with regard to good seamanship.