An Energy Scavenging Autonomous Surface Vehicle for Littoral Surveillance

A prototype energy scavenging autonomous marine surface vehicle for littoral water surveillance has been developed and experimentally tested. The basic vehicle chassis is a heavily modified Stiletto Catamaran with the center structure removed and replaced with an aluminum box beam supporting a carbon fiber stub mast. A carbon fiber rigid wing, 10.7 meters tall and with a 3 meter chord is suspended on bearings about the stub mast and able to rotate freely in azimuth. Controlled by flying tails attached on booms at mid-span, the wing flies at a constant angle of attack to the relative wind (the vector sum of the true wind and vehicle velocity). Equipped with two 7KW electric motors, and independent battery banks to power them, the vehicle can be propelled either electrically, or via wind power, or both. A simple hybrid drive results from the operation of two independent control systems linked through GPS velocity. Off shore tests have shown the vehicle to be capable of tracking patrol segments to better than 2 meters, with line acquisition and segment transitions taking 50-100 meters to complete. The control system for the wing automatically tacks and jibes the wing as appropriate in order to produce forward thrust.