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.

The vast capabilities of autonomous underwater vehicles (AUVs)-such as in assisting scientific research, conducting military tasks, and repairing oil pipelines-are limited by high operating costs and the relative inaccessibility of power in the open ocean. Wave powered AUV charging stations may address these issues. With projected increases in usage of AUVs globally in the next five years, AUV charging stations can enable less expensive and longer AUV missions. This paper summarizes the design process and investigates the feasibility of a wave powered, mobile AUV charging station, including the choice of a wave energy converter and AUV docking station as well as the ability to integrate the charging station with an autonomous surface vehicle. The charging station proposed in this paper meets many different commercial, scientific, and defense needs, including continuous power availability, data transmission capabilities, and mobility. It will be positioned as a hub for AUV operations, enabling missions to run autonomously with no support ship. The potential market for this design is very promising, with an estimated $1.64 million market size just for AUV technologies by 2025.

Abstract-This study is to develop prosthetic flippers for an injured sea turtle named "Yu" from the viewpoint of 3D (three-dimensional) hydrodynamic analysis of sea turtles' forelimb propulsion. Firstly template matching method is used to compare the 3D movements of fore flippers in three cases respectively: those of a healthy turtle, those of Yu with and without prosthetic flippers. Secondly 3D hydrodynamic analyses for three cases based on quasi-steady wing element theory are carried out to investigate the hydrodynamic effects of prosthetic flippers on the swimming performance of sea turtles. Finally the hydrodynamic effects are clarified and some remarks for designing new prosthetic flippers in future are given.Index Terms-forelimb propulsion of sea turtle, prosthetic flipper, template matching method, wing element theory