Optimize undulating motion of robotic fish

• Main Author: Petrus Ricky Handojo.
• Other Authors: Low Kin Huat
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Mechanical engineering::Robots
• Online Access: http://hdl.handle.net/10356/17113
• Institution: Nanyang Technological University

Nature has been showing us the most effective way of roaming in this world. Be it in land, water or air, nature has the best answer of how to move and interact in these different mediums. This facts lead to innovative mechanical designs to mimic the way of nature. And thus the multidisciplinary subject, the “Biomimetics”, is born as the result of human desire to improve the way man-made system interacts with this world. In NTU School of Mechanical and Aerospace Engineering, several robotic fish have been developed during the last couple years. They implement the MPF (Median and/or Paired Fin) locomotion. While these robots have an undisputed good performance, room for improvement will always be there. This final year project report addresses the issue of optimizing the undulating motion of the existing robotic fish by means of biological observation process supported by thorough literature search and followed by a series of parametric studies which reveal the relation between various undulatory and morphological parameters with the velocity attained by the robotic fish. The actual fin profile of the black ghost knife fish (Apteronotus albifrons) is derived through the biological observation process. From this profile it is observed that the profile exhibits asymmetry in the wave-form and thus the effect of this wave form asymmetry is further explored in the parametric studies. To support these parametric studies, a new prototype with oscillating fin-rays capable of implementing inclined fin-rays configuration is designed and built. This prototype, which utilize flexible membrane fin is observed to perform better than the old prototype in term of velocities. Finally, a series of parametric studies on the effect of undulation frequency - f, wave amplitude – a, fin-rays inclination angle – β, wave asymmetry coefficient – k and the wave amplitude envelope is carried out. The resultants data are plotted and further discussed.