Analysis on the Propulsion Force of an Ostraciiform Fish Robot with Elastically Jointed Double Caudal Fins and Effect of Joint Position on the Propulsion Force

Abstract

A simplified linearized dynamic equation for the propulsion force generation of an Ostraciiform fish robot with elastically jointed double caudal fins is derived in this paper. The caudal fin is divided into two segments and connected using an elastic joint. The second part of the caudal fin is actuated passively via the elastic joint connection by the actuation of the first part of it. It is demonstrated that the derived equation can be utilized for the design of effective caudal fins because the equation is given as an explicit form with several physical parameters. A simple Ostraciiform fish robot was designed and fabricated using a microprocessor, a servo motor, and acrylic plastics. Through the experiment with the fish robot, it is demonstrated that the propulsion force generated in the experiment matches well with the proposed equation, and the propulsion speed can be greatly improved using the elastically jointed double fins, improving the average speed more than 80%. Through numerical simulation and frequency domain analysis of the derived dynamic equations, it is concluded that the main reason of the performance improvement is resonance between two parts of the caudal fins. . 따라서, 군사적 감시활동, 해 저탐사 [5] , 수중환경 감시, 생태학적 연구 등의 수중 임무 수행을 위한 차세대 수중 운행체 [6] 를 개발하기 위한 방 편으로 물고기 모방 로봇을 개발하기 위한 많은 연구들이 이루어지고 있다. 1994년에 개발된 MIT의 RobotTuna [7] 를 시작으로 많은 물고기 모방 로봇들이 개발되었다.RobotTuna의 뒤를 이어 RoboPike 자율 수중 운행체라고 할 수 있다 [9,10] . 이 외에도 California Institute of Technology [11] , University of California San Diego 및 Northeastern University [12] , University of California Berkley [13] , Essex University [14] , Tokai University 및 National Maritime Research Institute (NMRI) [15] , Peking University [16] , 서울대학교 [29] , 건국대학교 [17,22] , 충주대학교 [18] , Institute Technology Bandung [19] , 울산대학교 [28] 등에서 물고기 로봇 관련 연 구들이 이루어지고 있다.