The Theseus autonomous underwater vehicle. A Canadian success story

International submarine Engineering Research and the Esquimalt Defence Research Detachment of the Defence Research Establishment Atlantic have worked together to develop a large autonomous underwater vehicle, named Theseus, for laying optical fiber cables in ice-covered waters. It was able to lay a fiber optic cable in a completely autonomous mode for a distance of 200 km under Arctic sea-fee and then return to the launch station for recovery. It operates in either depth-keeping mode or bottom-following mode, was designed to operate at a maximum depth of 1000 m, and has operated at a depth of 425 m. The vehicle is equipped with an inertial navigation unit and Doppler sonar speed sensor for autonomous navigation, a forward-looking obstacle avoidance sonar, an acoustic homing system, and acoustic transponders for use with surface tracking stations. An acoustic telemetry system enables communication with Theseus from surface stations, and an optical telemetry system is used for system monitoring while Theseus is laying optical fiber cable. All sub-systems are controlled by an MC68030 based sensor integration and control computer. Theseus' qualities of covertness, long endurance and precise navigation make possible such tasks as long base-line oceanographic data collection, remote route surveys, remote mine hunting, the rapid deployment of acoustic and non-acoustic surveillance systems, and even the towing of mobile sensor arrays. The paper describes the vehicle and presents the results of the evaluation trials and its first cable laying mission.