Remotely operated underwater vehicles (ROVs) are the common accepted name for tethered underwater robots in the offshore industry. ROVs are unoccupied, highly maneuverable and operated by a person aboard a vessel. They are linked to the ship by a tether, like the one scene in Figure 2. A tether is a group of cables that carry electrical power, video, and data signals back and forth between the operator and the vehicle. High power applications will often use hydraulics in addition to electrical cabling. Most ROVs are equipped with at least a video camera and lights. Additional equipment is commonly added to expand the vehicle’s capabilities. These may include sonar, magnetometers, a still camera, a manipulator or cutting arm, water samplers, and instruments that measure water clarity, light penetration and temperature
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(Figure 1) (Figure 2)
ROVs range in size from that of a bread box to a small truck. Deployment and recovery operations range from simply dropping the ROV over the side of a small boat to complex deck operations involving large winches for lifting and A-frames to swing the ROV back onto the deck. Some even have “garages” that are lowered to the bottom. The cabled ROV then leaves the garage to explore, returning when the mission is completed. In most cases, however, ROV operations are simpler and safer to conduct than any type of occupied-submersible or diving operation.
Conventional ROVs are constructed with a large flotation pack on top of a steel or alloy chassis, to provide the necessary buoyancy. Syntactic foam is often used for the flotation. A tool sled may be fitted at the bottom of the system and can accommodate a variety of sensors. By placing the light components on the top and the heavy components on the bottom, the overall system has a large separation between the center of buoyancy and the center of gravity; this provides stability and the stiffness to do work underwater. Electrical cables may be run inside oil-filled tubing to protect them from corrosion in seawater. Thrusters are usually located in all three axes to provide full control. Cameras, lights and manipulators are on the front of the ROV or occasionally in the rear for assistance in maneuvering.
(Figure 3)
The disadvantages of using an ROV include the fact that the human presence is lost, making visual surveys and evaluations more difficult, and the lack of freedom from the surface due to the ROV’s cabled connection to the ship. An ROV operator controls the vehicle from a system on board the ship. Using a joystick, a camera control, and a video monitor, the operator moves the vehicle and the camera to desired locations; the operator’s eyes essentially “become” the camera lens.
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(Figure 1) (Figure 2)
ROVs range in size from that of a bread box to a small truck. Deployment and recovery operations range from simply dropping the ROV over the side of a small boat to complex deck operations involving large winches for lifting and A-frames to swing the ROV back onto the deck. Some even have “garages” that are lowered to the bottom. The cabled ROV then leaves the garage to explore, returning when the mission is completed. In most cases, however, ROV operations are simpler and safer to conduct than any type of occupied-submersible or diving operation.
Conventional ROVs are constructed with a large flotation pack on top of a steel or alloy chassis, to provide the necessary buoyancy. Syntactic foam is often used for the flotation. A tool sled may be fitted at the bottom of the system and can accommodate a variety of sensors. By placing the light components on the top and the heavy components on the bottom, the overall system has a large separation between the center of buoyancy and the center of gravity; this provides stability and the stiffness to do work underwater. Electrical cables may be run inside oil-filled tubing to protect them from corrosion in seawater. Thrusters are usually located in all three axes to provide full control. Cameras, lights and manipulators are on the front of the ROV or occasionally in the rear for assistance in maneuvering.
(Figure 3)
The disadvantages of using an ROV include the fact that the human presence is lost, making visual surveys and evaluations more difficult, and the lack of freedom from the surface due to the ROV’s cabled connection to the ship. An ROV operator controls the vehicle from a system on board the ship. Using a joystick, a camera control, and a video monitor, the operator moves the vehicle and the camera to desired locations; the operator’s eyes essentially “become” the camera lens.
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