The Design And Dynamic Analysis Of A Pectoral-fin Propelled Bionic Robotic Fish With Two Free Degrees

In recently years, the research on efficient underwater vehicles, which takes the fish as abionic object, has attracted many researchers in robotic field. Until now, many works arefocused on Body and/or caudal fin (BCF) propulsion modal and a little consider the Medianand/or paired fin (MPF) propulsion modal. Especially, the works on MPF mainly consider themechanism with one free degree. Here, a robotic fish driven by pectoral fin with two freedegrees is designed by taken Trachidermus Fasciatus as bionic object. The main contents areas follows:Firstly, a new propulsion mechanism is designed for a bionic robotic fish with twodegrees of freedom pectoral fin. Taken the trachidermus fasciatus’s appearance characters asreference, a new propulsion mechanism is proposed such that the pectoral fin of robotic fishhas two degrees of freedom. The proposed mechanism not only can carry out the lead-lagmotion and feathering motion respectively but also can achieve the compound movement ofthese two basic motions. Thus, the proposed robotic fish has more rich movement mode thanthe former.Secondly, the structural parameters of propulsion mechanism are optimized such that thevolume of robotic fish is minimized. The results of optimization show that the structure of thepropulsion mechanism not only can be installed in a small space but also obtain a lightweightrobotic fish. Meanwhile, the robotic fish’s swimming performance has been improved.Thirdly, the model of rigid pectoral fins is first established. The movement modal,dynamic and dynamic balance of robotic fish is analyzed by using ADAMS. The obtainedresults include three aspects:①the conditions are established based on D-H method suchthat the robotic fish can swim in a straight style or turning.②Three ways of the straightswimming, including the backward swimming, and turning movement, are given.③Thedynamic balance of bionic mechanism is analyzed and the results reveal that the certain ofmechanism changed can be eliminated by adding clump weight or using light material, thevalidity of the design is verified.