The Dynamic Analysis And Control Of Pectoral-fin Propelled Bionic Robotic Fish With Two Degrees Of Freedom

As the high-tech tool of sea detection, underwater robots plays an important role in developing and utilizing oceans, which is the most realistic space for the survival of human beings in the future. Since fish has the outstanding ability under the water, they are the most suitable prototypes for the design of underwater robot. Many biomimetic robotic fish, which have the advantage of high efficiency, high maneuverability, low noise, and the low disturbance to the environment, have been designed by employing the propulsion mechanism of fish and widely used in the fields of ocean biological observation, military reconnaissance, underwater archaeology, underwater pipeline detection, water environmental condition monitoring, etc.. Taken the cowfish papaya as a prototype, this dissertation designs a biomimetic robotic fish that is propelled by two degrees of freedom pectoral fins and a single joint caudal fin. Meanwhile, its swimming modes are analyzed including straight swimming, turning and stop mode. The main contents are as follows.(1) The propulsion mechanism of biomimetic robotic fish is designed. By analyzing the existed rigid pectoral fin propulsion mechanism and summing up the typical mechanism which can achieve the flapping or rowing, a pectoral fin propulsion mechanism with two degrees of freedom is designed that can achieve the flapping, rowing and their compound movement. Furthermore, the shell of biomimetic robotic fish is designed according to the requirement of shape bionics and the hydrodynamics of fish. Finally, the caudal fin propulsion mechanism with single joint are designed, too.(2) The propulsion mechanism of the proposed biomimetic robotic fish is analyzed. Firstly, the hydrodynamics models of pectoral fin and caudal fin are proposed by using the fluid mechanics theory. Then, the propulsion mechanism is analyzed including straight swimming, backward swimming, turning and stop mode. Based on this, the dynamics model of each swimming mode is established and the performance parameters of them are determined. The obtained results provide theoretical basis for physical experiment.(3) The theoretical results are verified by experiment. The prototype of the proposed biomimetic robotic fish is manufactured and its control systems are also designed and debugged. Then, the experimental platform is established and the theoretical results are verified by experiment. Combined with the results of theoretical analysis and experiment, the final modes of the proposed robotic fish are determined.