Abstract
This paper is aiming at investigating the effects of flexibility and chord-wise cross section of pectoral fins on the swimming performance of the biomimetic underwater vehicle PLATYPUS by designing and making new types of pectoral fins. Experiments using a mechanical pectoral fin device BIRDFIN fixed in uniform flow verify the advantage of fin flexibility in underwater robot control. Fundamental experiments using PLATYPUS investigate the roles of both fin flexibility and chord-wise cross section in propelling underwater vehicles and iterative computation of spanwise deformation between Finite Element software and wing theory analyze the hydrodynamic characteristics of these new pectoral fins. Finally PTP control tests in still water and water currents check the different performances of each fin in carrying out specific task, and at the meantime the fuzzy control rules are revised to find the most suitable one for each fin respectively. It is found that asymmetric flexible fin (harder) behaves best in PTP control in still water but symmetric rigid fin does best in PTP control in water currents.
