Research Dynamics Of Hopping Kangaroo Robot With Nonlinear Joint

The kangaroo's complaisant joints and toes make it hop stable and has low Oxygen consumption. Adding complaisant mechanism into kangaroo hopping robot can improve the location and driving characters. On the base of kangaroo's biological construction, this paper developed a complaisant hopping model , than analyzed how nonlinear joint and complaisant foot work and improve the hopping capability of system.First of all, on the base of referring dozens of references of bionic robotics' motion stability home and abroad, this paper summarized the basic theory of the research on the hopping robot. After analyzing the kangaroo hopping video and the measuring reports, the characters of its gait and energetics were elucidated. The biological character of kangaroo's muscles and tendons were analyzed and showed a importance for a low rate of oxygen comsumption.Next, a kangaroo robot considering joint's nonlinear stiffness was designed based on kangaroo leg's biological architecture and hopping characteristics. Kinematics and dynamics of the model in the contact process are established. Curves that each joint angle, joint moment and nonlinear twist spring's torque with the time in the process are obtained using Matlab, and discussed contrast to linear joint. Computer simulation shows that joint's nonlinearity can not only enhance its engery storage ability, effective reduce joint's torque, but also can avoide nagative hopping, improve hopping capability, what is in favor of higher hopping velocity and longer distance. It more accords with biological characteristics.Than on the base of kangaroo hopping robot with flexible foot, a pseudo-rigid-model was kinematic and dynamic analyzed. The elastic strain energy of the flexible joints and the kinetic, potential energy of total hopping machine were calculated. How these energy were distributed and consumed, and how they translated between each other was discussed. The ankle joint torque of rigid- and pseudo-rigid-model were contrasted. Apparently the hopping mechanism benefits from elastic strain energy of flexible joints on driving. This can explain why kangaroo has a relative low rate of oxygen consumption while running with a high speed.Finally, the three functions of flexible feet in stance phase were studied:...