Design And Control Of Autonomous Biomimetic Robotic Fish

Nowdays, research of biomimetic robotic fish is one of the hot spots, and the imitation of fish propulsion is the future development direction of underwater robot propulsion mode. We studied the fish propulsion principles, designed and established the multi-joint robotic fish platform that costed less but possessed more value, and then carried out some experiments on auto-swimming and intelligent control of robotic fish.According to the research on fish locomotion mechanism of bionics, we established three-dimensional model of four-joint carangidae robotic fish with moon-shape caudal fin, simulated and analyzed its structural strength and whole fish swimming resistance. By adopting the method of mathematical modeling, swimming fish’s cruise model and C-type quick turn model were established based on Lighthill equation.After analyzed and summarized up the key problems(for example, weight, seal, tail simulation scheme, fin shapes and parameters) in the process of design of robotic fish, we developed the general steps of design of robotic fish, from part planning to overall coordination.The robotic fish physical research platform consisted of three modules was built. One is the perception module based on kinds of sensors, one is the decision-making module based on ARM micro-processors and Linux system and another one is the execution module based on servos and their controller.The robotic fish’s three-layer control strategy was firstly proposed, from low to high respectively was swimming style layer, swimming behavior layer and intelligent learning layer. The robotic fish’s obstacle-avoiding strategy-- "security zone method" was put forward. Based on the two strategies, the autonomous robotic fish’s swimming algorithm was developed.To verify the correctness and reliability of the control algorithm and the performance of the robotic fish, many underwater dynamic experiments were carried out, and we measured the related parameters of the evaluation of robotic fish such as speed, acceleration, turning time and radius. Analyzed the influence of parameters of the robotic fish’s swimming, for example, the relationship between tail propelled robotic fish’s swimming speed and amplitude and frequency of tail movements. These experiments showed that the robotic fish can successfully swimming freely like a real fish underwater. They also proved the validity of this platform’s design methods and the effectiveness of three-layer control strategy and the " security zone method ".