Experimental Verification of Lifting Force of Underwater Robot with Thrusters Using Passive Posture Maintenance

Abstract

An underwater robot is developed that can be used for environmental protection work in the sea near Okinawa (e.g., removing crown-of-thorns starfish). When a submerged object is raised with the aid of an underwater robot, the conventional method of using fixed thrusters presents difficulties in raising the object straight upward because of the change in the robot’s attitude. Therefore, we propose “thrusters that employ a passive posture maintenance mechanism.” By using this mechanism, the vertical thrusters are able to maintain an upward posture, and the underwater robot is able to raise a submerged object straight upward relatively easily. Moreover, the attitude stability of an underwater robot and the work efficiency of its thrusters are important in water. Hence, we examine the attitude stability and the efficiency of the lifting force of an underwater robot using our proposed passive fixed mechanism for thrusters. We describe the design and fabrication of the proposedmechanismand experimentally verify the effectiveness of our proposed mechanism.