Definition of detection and reaction boundaries for autonomous marine vessels

Abstract

Definition of Detection and Reaction Boundaries for Autonomous Marine Vessels investigates the possibility of using a time-based self-separation method for safely navigating a controlled vessel with oncoming vessels and obstacles, which may or may not adhere to the appropriate guidelines for encounter navigation with another vessel. The simulation uses a validated model of a test vessel in order to accurately describe vessel dynamics when operating at a given desired speed, with an identical oncoming vessel. The simulation is used to calculate the last possible time before a collision would occur that the controlled vessel must begin manoeuvring in order to maintain a desired amount of separation with the intruder, regardless of whether the vessel is navigating properly or not. The algorithm was also tested in varying environmental conditions through a Monte Carlo simulation in order to confirm the results in non-calm water situations. All results presented are with both the controlled vessel and intruding vessel travelling at 10 knots with a fixed maximum turn rate. There is a desired separation boundary of twice the length of the vessel from the centre point of the vessel, in all directions. The effects of changing the speed and size of the separation boundary were analyzed, and it was found that increasing the size of the separation boundary results in the vessel requiring more time to manoeuvre, while increasing the speed decreases the time required. Each of these relations between the time required to safely manoeuvre and the changing parameters are approximately linear. From the simulations, it was determined that the test vessel in a head-on encounter scenario must begin manoeuvring approximately 3 minutes with a non-compliant intruder and slightly more than 2 minutes for a compliant intruder. For a crossing scenario, the controlled vessel must begin to manoeuvre at least approximately 8 minutes prior to the closest point of approach for the intruder in order to maintain the desired separation. Lastly, for an overtaking scenario, with the intruder travelling at 80% of the speed of the controlled vessel, the controlled vessel must begin to manoeuvre once again, approximately 8 minutes prior to the closest point of approach. Note that in certain environmental conditions, more time may be required to manoeuvre effectively.