on pectoral fin motion simulation of a Biomimetic Autonomous Underwater Vehicle

• Main Authors: chi-kang chen, 陳紀綱
• Other Authors: chiu forng-chen
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/32983255896182900854

碩士 === 國立臺灣大學 === 工程科學與海洋工程學系 === 91 === For predicting the dynamic characteristics of a fishlike AUV tested, we developed a practical method to simulate the undulatory locomotion of a flexible slender body. when the flexible slender body which is divided into a number of segments undulates, the wave passes from the nose to the tail, the reaction forces due to momentum change, friction as well as cross flow drag acting on each segment are taken into account. Equation of motion described by the body-fixed coordinate are obtained by taking the summation of the longitudinal force, lateral force and yaw moment acting on all the segment, respectively. Equation of motion are solved step by step in time axis and the velocity is transferred to spaced-fixed coordinated. Then the trajectory of the flexible body can be obtained easily just by time integration of the transferred velocity. We also developed a practical mathematical model to evaluate the hydrodynamic forces of a pectoral fin rowing. Basically assumptions of Blade element theory are followed and the fin is treated as a number of moving blade element. The lift, cross flow drag and added inertia acting on each blade are evaluated as a two dimensional oscillating thin foil and they are described in the fin-fixed coordinate. These forces are transferred to the fuselage-fixed coordinate and integrated to obtain the total forces acting on a pectoral fin. The calculated results of the research are compared with the model tests and calculation carried out by Kato. The agreement confirmed that the presented mathematical model is a practical tool for simulating the locomotion and maneuvering motion of a fishlike AUV in pectoral fin rowing motion. In numerical simulation, digital filtering technique is applied to avoid drifting in sway and yaw motions, and can be obtained the steady state solution.