Parameters Analysis And Optimization Of Quadruped Robot With Bounding Gait

Among legged robots, Quadruped robot is good at static stability and has low redundancy and complexity on mechanism. The characteristics such as flexibility and isolated footholds provide quadrupeds better mobility on irregular, unknown environments. Therefore, the design of quadrupeds becomes the research hotspots recently. However, the theory on this has not been adequately studied and the impact of parameters on the robot performance needs to be investigated systematically which would benefits the design and optimization. Overall, the research of quadrupeds parameters'impact has practical significance in the design and control of robots.This thesis is supported by National Hi-tech Research and Development Program of China (863 Program, Grant No. 2011AA0403837002), National Natural Science Foundation of China (No. 61005076), Self-Planned Task (NO.SKLR2008011B) of State Key Laboratory of Robotics and System (HIT). In paper, based on the mechanisms of bionics and numerical simulation methods, we carried out the research about the relation between parameters such as spring stiffness and performance such as speed, stability for bounding gait. Frstly, analyzed the characteristics of typical tetrapod gaits, identified bounding gait as the research object and then established models with a progressive relationship. based on equivalent model method, proposed search strategy of fixed points, sovled the problems such as the critier of stability, the selection of step length and direction. besides, the gait of quadruped robot plane model is discussed.Secondly, use dimensional analysis to determine the dimensionless parameters of the model, greatly improving the simulation efficiency. As to Spring Loaded Inverted Pendulum model, analyzed the height mapping, pointed out the classification, distribution and the performance of speed and pitch of fixed points, studied the impact on system by the mass, spring stiffness and so on. As to plannar model, carried out the analysis of the distribution of fixed points on different energy levels, found the bifurcation and chaotic phenomena of the gait, identified the specific method of gait adjustment and its applications were discussed. Analyzed the distribution of speed and height, developed the strategy of speed adjustment, pointed out the relationship between the moment of inertia, the robot morphology and stiffness characteristics with the robot performance. Finally, designed the simulation platform for quadruped bounding robot, established the control strategy based on the low of fixed points mapping, simulated the start progress of the robot, found the mechanism to improve the performance by non-symmetrical arrangement, for example, making the center of mass preposed and front legs decreased. completed the simulation experiments of speed and gait adjustment, verify the results of the theoretical analysis.