Abstract In order to reduce tension on a cable and process movability, a deep sea remotely operated vehicle (ROV) is designed to reduce its weight. However, a lightweight ROV is apt to wheelie when running by means of a crawler system. To run stably in counterpoise, the combination of the center of gravity and the center of buoyancy should be in an adequate area called the “stable area,” which by theory can be obtained as corresponding to the weight and the buoyancy. The stable area becomes small as the weight is light. The combination of the center of gravity and the center of buoyancy is designed to be in the stable area. However, it is important for the ROV to run forward and backward, which results in changing the discrimination of the stable area. This sometimes causes the center of gravity and the center of buoyancy to be outside the stable area. Thus, it is advantageous to increase the weight only when running by crawler system and to change the center of gravity meaningfully. Furthermore, the flipper-type crawler system is advantageous when running on the sea floor with inclination or undulation. This paper proposes a method to virtually increase the weight and to change the center of gravity by using thrusters. This paper also describes the flipper-type crawler system that improves movability when running on the sea floor with inclination or undulation. Furthermore, we conducted preliminary experiments in a water tank using a small-size ROV having four thrusters and a crawler system, a normal-type crawler, and a flipper-type crawler system, to confirm the advantages.
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