Collision Avoidance System

For the ASV to obey the rules-of-the-road during when encountering other manned and/or unmanned vehicles, and perform the correct and predictable actions in haz- ardous situations the CAS needs to be COLREGS compliant. From the Mission Planner the CAS receives a desired course and speed based on a sequence of waypoints. These waypoint could for instance be generated by a human operator in Neptus. Meanwhile, the Sensor System composed of e.g. Radar, AIS, Lidar, etc. continually provides naviga- tional measurements, measured obstacle positions and predicted trajectories. Based on this information the CAS module searches for a COLREGs compliant and collision-free trajectories through a series of simulations with a finite set of offsets to the nominal course. The offset associated with the lowest cost while producing a collision-free and COLREGs compliant trajectory is selected as the new modified course reference and is passed on to the autopilot. If there is no obstacles in the vicinity the desired course and speed from the Mission Planner are sent to the Autopilot, composed of a Heading and a Speed Controller. Consequently, the ASV’s Autopilot and Steering and Propulsion System will apply these (modified) steering and propulsion commands, ensuring a COLREGs compliant trajectory associated with the lowest collision risk as possible. When the original desired course and trajectory no longer contains any possible potential collisions, the ASV would return to the desired nominal path and proceed towards the target destination.