Mechanism Design And Simulation Of Wheel-leg Hybrid Quadruped Robot

In modern times, natural disasters such as earthquakes, volcano and ect frequently occur, the threat of nuclear pollution aggravates and regional military conflicts increase. Therefore, there is an urgent demand of intelligent robots to replace human to complete the tasks in these high-risk situations. Wheel-leg hybrid robot is receiving sustained attention of research institutions from each nation and gradually becoming the hotspot and trend in this field with its outstanding obstacle crossing ability and great adaptability. In this study, combing the advantages and disadvantages of the existing wheel-leg hybrid robots, the innovative series-parallel leg mechanism is designed and solves the problems such as poor bearing capacity and low flexibility that are general among the robot system.First of all, the intense demand of the wheel-leg hybrid quadruped robot and a thoughtful overview are studied. Then an innovative wheel-leg hybrid quadruped robot is proposed based on the analysis of robot’s movement performance requirement and bionics.The design process is introduced in detail. The mathematical model is established ignoring its complex geometrical shape and solves the degrees of freedom both of the single leg and of the whole machine in different gait using screw theory. Besides, the optimization of the series-parallel mechanism is conducted based on velocity and force performances and a group of optimal parameters obtained based on genetic algorithm. A new trajectory of the foot and gait planning is proposed which guaranty the efficiency and stability in the leg mode of the robot. The stability of the wheel mode is also analyzed. At last, using the 3D model of the Solid Worksthe simulation and analysis is carried out in accordance with the planed gait and trajectory in the multibody system kinematics simulation software Recur Dyn, the curves of each joint are obtained.The serial-parallel mechanism meeting the movement requirements is applied in the leg structure for the first time in this kind of study and creatively solves the problem of poor flexibility and low bearing capacity that exist in this kind of robots at present. Also, the separate frame fully absorbs the shock force from the ground robot in the high-speed motion, greatly improving the energy utilization efficiency. Moreover, the combination of the leg structure and wheel mechanism compromises the advantages of these two institutions perfectly without mutual interference and interaction. The complete simulation prove the rationality of the mechanism and the stability of the robot.The wheel-leg hybrid serial-parallel mechanism quadruped robot is studied for the first time. It has valuable theory and significant influence to the future development of prototype.