The Remote Unmanned Work System (RUWS), precursor to the Advanced Tethered Vehicle, was designed to perform a variety of work tasks at ocean depths as great as 20,000 feet (6100 m), giving it access to 98% of the ocean floor.
The work system itself included a hydraulically powered, master/slave arm with seven functions including grip. The arm was terminus-controlled: the operator moved a simple pistol grip to control the position and orientation of the remote manipulator hand. It was also bilateral, or force-feedback: weights and forces encountered by the remote arm were reproduced at a scaled-down level in the master arm and thus felt by the operator. A second four-function arm or gripper, simpler and more rugged, was used to steady RUWS with respect to the work or work site.
The system actually consisted of two vehicles. The second was a heavy Primary Cable Termination (PCT) to which the work vehicle was firmly attached during deployment and recovery, and which carried a cable reel for the 850 foot neutrally buoyant portion of tether. The functions of the PCT were to maintain tension in the primary cable, provide position-keeping capability to its bottom end, and to launch and recover the RUWS vehicle itself. In effect, the PCT was a highly sophisticated plumbob, keeping the main umbilical section vertical and isolating the RUWS from its motions.
Another vital component of the system was the Motion Compensating Deck Handling System (MCDHS), an extremely versatile combination of launch crane and cable reel. Its purpose was to launch and recover the RUWS vehicle/PCT combination and to tend the primary cable, minimizing ship-induced motion and tension therein. It was capable of operating in sea state three and recovery in sea state four.
RUWS was lost at sea in January of 1980. The cause was determined to be a design flaw in the mechanical attachment to the PCT. Search efforts proved futile due to the extremely rough scarp bottom. RUWS is currently undergoing what is termed "long-term corrosion tests" at 13,500 feet depth approximately 15 miles West of Kona, Hawaii.