Development of a Bioinspired Underwater Robot Using a Single Actuator

Abstract

Abstract We propose a novel propulsion mechanism for an underwater robot inspired by the pectoral fins of a fish. This device is referred to as the “flipper.” The flipper is connected to a rotational motor, and its shape is similar to that of the real fish's fins. The flipper using the propulsion mechanism proposed in this study has 1 degree of freedom. We can control the test robot during forward motion as well as its direction-changing operation. The experimental test robot is composed of a flipper at the front of the robot's head, together with a body and a tail/vertical fin. The electronic components are installed into the body. The tail functions to maintain the horizontal/vertical balance of the robot. Forward propulsion is achieved through the rotation of the flipper. The robot's direction can be changed by repeated oscillation of the flipper in a direction opposite to that of the desired angle. Several experiments were performed to measure the thrust force of the experimental robot and its motion characteristics in a test water pool. The experimental results show that the proposed propulsion method is viable.<def-list> Nomenclature <def-item> <term> F T </term> <def> = Thrust </def> </def-item> <def-item> <term> F I </term> <def> = Inertia force </def> </def-item> <def-item> <term> F B </term> <def> = Buoyancy </def> </def-item> <def-item> <term> B V </term> <def> = Platform volume </def> </def-item> <def-item> <term> V target </term> <def> = Target speed </def> </def-item> <def-item> <term> ρ </term> <def> = Water density </def> </def-item> <def-item> <term> P </term> <def> = Flipper pitch </def> </def-item> <def-item> <term> D </term> <def> = Drag force </def> </def-item> <def-item> <term> C D </term> <def> = Drag coefficient </def> </def-item> <def-item> <term> A </term> <def> = Projection of the frontal area </def> </def-item> <def-item> <term> T </term> <def> = Effective power </def> </def-item> <def-item> <term> P m </term> <def> = Propeller power </def> </def-item> <def-item> <term> C M </term> <def> = Center of total body mass </def> </def-item> <def-item> <term> C B </term> <def> = Center of buoyancy </def> </def-item> <def-item> <term> C F </term> <def> = Center of flipper mass </def> </def-item> <def-item> <term> F DS </term> <def> = Restoring force </def> </def-item> <def-item> <term> g </term> <def> = Gravity </def> </def-item> <def-item> <term> Q </term> <def> = Motor torque at maximum revolutions per minute </def> </def-item> <def-item> <term> rps reasonable </term> <def> = Reasonable revolutions per second </def> </def-item> </def-list>