Research On Design And Key Technologies Of Frog-inspired Swimming Robot Actuated By Penumatic Muscles

With the development of water resources exploration and development, water detection and early warning or other scientific and military areas of demand, the underwater robot technology has been developed rapidly. Inspired by the biological in nature, the researchers have developed a variety of biomimetic underwater robots. Frog has many forms of motion, such as swimming in water, jumping on the land, and crawling on the bank. It has important practical significance to develop a frog-inspired robot which has the characteristics of three forms of motions, which can reach the area where the traditional underwater robot and legged robot cannot reach. At the present stage, the research on the underwater movement of frog is less, in this paper, we will study the bionic frog swimming robot, constantly enrich and improve the underwater propulsion technology, expand the scope of application of underwater robots, and lay the foundation for the development of an amphibious frog-inspired robot.Firstly, the physiological structure and movement characteristics of the frog were analyzed, also the skeletal structure and the characteristics of swimming process of frog were studied, then we abstracted the body and hind limb mechanism, getting a simplified model and optimized it. A joint model was established which was driven by antagonistic pneumatic muscles, relating parameters affecting the joint angle and torque were optimized, and these provided reference for the design of robot mechanism.Secondly, the hip, thigh, calf, flippers and other hind mechanism of the robot were designed. In order to realize the autonomous swimming, a small high pressure pneumatic system was designed and integrated into the trunk of the robot. The curved surface modeling of the trunk and the hind limbs of the robot was carried out to complete the design of the seal in water. Then, the design of the robot body was finally completed.Besides, based on the research of the hydrodynamic force of the robot motion, trunk and hindlimb movement resistance and flippers propulsion model was built. The mathematical model of robot dynamics was established by Lagrange equation, and inverse dynamics method was analyzed. Based on the dynamic equation and motion constraints, the trajectory planning optimization model was established, and the optimal joint trajectory was obtained. The simulation model was established in ADAMS, and the driving torque of each joint was obtained by using the optimal trajectory, and the simulation results were compared with th e Matlab simulation results to verify the correctness of the dynamic model and trajectory planning.Finally, the robot motion control strategy was analyzed and the software and hardware control system was built. Experiments of the hind limb were carried out to verify the rationality of hind limb mechanism, pneumatic system and control system. The application feasibility of the whole system of the frog swimming robot driven by pneumatic muscle was verified by the experiment of the swimming experiment in water.