ROPOS, is a remotely operated vehicle designed to carry out a wide range of scientific explorations at depths of up to 5,000 meters. ROPOS weighs 6,000 lbs. and measures 5 ft wide x 9 ft long x 7 ft high. The vehicle operates in two modes - deep and shallow water. For missions in deep water (350 - 5000 m depth), ROPOS is lowered to its target depth nestled inside a large steel cage weighing 11,000 lbs. When the cage arrives at the dive target, ROPOS exits the cage and operates freely on 300 ft of tether. For deep-water operations, ROPOS requires a vessel with an A-frame or crane capable of lowering and hoisting 14 tons or more; this is the combined weight of ROPOS, its cage, and the 5,500 m of electrical-optical cable tethering the entire system to its support ship. When deployed in shallow water (<350 m), ROPOS operates without its cage. Over the years, the ROPOS system has logged over 3,500 operating hours in its 1400+ dives.
ROPOS recovering a hydrophone near Vancouver BC, Aug 2012. Click image for larger view.
Schematic image of ROV deployment and support equipment (drawing is not to scale). Click image for larger view.
While oceanographic exploration is, by its very nature, an expensive undertaking, the costs associated with deploying a deep diving submersible and providing for its support vessel are enormous. This was a major consideration for the engineers who designed the ROPOS; thus, the vehicle was built to maximize its research effectiveness on each and every dive. ROPOS carries a suite of "core" observation tools. These include two digital video cameras (one mounted on the vehicle, another mounted on the cage); two manipulator arms, each capable of lifting up to 600 lbs, that can be fitted with different sampling tools, such as stainless steel jaws, manipulator feedback sensors, rope cutters, snap hooks, and core tubes; a variable-speed suction sampler and rotating sampling tray; sonar; and a telemetry system. ROPOS can also be outfitted with up to eight additional custom-designed observation tools specific to each mission. This equipment can be installed in any one of its eight available hydraulic power packs. Examples of custom-designed tools include a hot-fluid sampler, chemical scanner, tubeworm stainer, rock-coring drill, rock-cutting chainsaw, laser-illuminated, range gated camera, and downward-looking digital scanning sonar. ROPOS’ ability to carry such a wide variety of observation tools on each dive provides scientists with exceptional flexibility, as they can quickly respond to new and unexpected discoveries on the sea floor.
All data collected by ROPOS are simultaneously transmitted to the vehicle’s pilot, a bank of video recorders, and a data-management recorder. The data-management recorder logs all of the observational and navigational data collected during a dive, and keeps the pilot apprised with a continuously updated readout of the ship, cage, and vehicle positions. While ROPOS is designed to be relatively easy to operate, the amount of information dispatched during a "typical" dive requires at least four people (and sometimes more) to be present in the control room. These four individuals are the "Hot Seat" scientist, pilot, manipulator operator, and data/event logger.
The scientist provides ultimate direction to the pilot and manipulator operator through a series of successive data-collection tasks during each dive. The scientist also provides audio commentary for the video archive via the data/event logger. The manipulator operator must be proficient in operating all of ROPOS’ observational tools, cueing off the scientist’s instructions. The data logger must accurately note significant events that occur during the dive. Logging events in real time during the dive can save researchers literally hundreds of hours of laboriously poring over videotape and spreadsheets.
While all of these individuals aid in increasing the efficiency of a multi-disciplinary expedition, no one’s position is more critical than the pilot’s. ROPOS’ pilot must be acutely aware of the full range of scientific and navigational data that the vehicle is transmitting topside, while, at the same time, focusing on the instructions of the scientist and the actions of the manipulator operator. If the pilot miscalculates ROPOS’ speed, position, or orientation, it could become entangled or damaged, compromising the mission, or the vehicle itself.
To prevent entanglements and position miscalculations, ROPOS and its cage are navigated with a sonar-based tracking system aided by a global positioning system (GPS). The vehicle is powered by a 40-horsepower electric motor when operating in shallow-water mode. In deep-water mode, the motor generates 30-horsepower for ROPOS itself, and 10 for the cage.
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