A micro-robot fish with embedded SMA wire actuated flexible biomimetic fin

A flexible biomimetic fin propelled micro-robot fish is presented. Fish muscle and the musculature of squid/cuttlefish fin are analyzed firstly. Since the latter one is easier to be realized in the engineering field, it is emulated by biomimetic fin. Shape memory alloy (SMA) wire is selected as the most suitable actuator of biomimetic fin. Elastic energy storage and exchange mechanism is incorporated into the biomimetic fin for efficiency improvement. Furthermore the bending experiments of biomimetic fin were carried out to verify the original ideas and research concepts. Thermal analysis is also conducted to find a proper actuation strategy. Fish swimming mechanism is reviewed as the foundation of the robot fish. A radio frequency controlled micro-robot fish propelled by biomimetic fin was built. Experimental results show that the micro-robot fish can swim straight and turn at different duty ratios and frequencies. Subcarangiform- and carangiform-like swimming modes were realized. The maximum swimming speed and the minimum turning radius reached 112 mm/s and 136 mm, respectively.