Gait Planning And Walking Stability Research Of Quadruped Bionic Robot

This thesis is based on National High Technology Research and Development Program(863 Program) with the title of ‘High performance Quadruped bionic robot prototype system’. In order to improve the stability of motion, a type of quadruped bionic robot was chosen as the research target, basing on an improved kind of Central Pattern Generator(CPG), several typical gaits were planned and kinematics as well as dynamics simulation were done. For the purpose of discovering motion patterns and building effective computer aided design tools, evaluation theory of robot’s stability was put forward and the influence of mechanical parameters and gait parameters on robot’s stability were analyzed. The main works done of this thesis is listed as follows:1) A virtual prototype model of quadruped bionic robot, with the function of editable variables, was set up on the fountain of Adams and Matlab software. By the means of DH description, the kinematics equations of a bionic leg were derived and its inverse kinematics equations were obtained. To realize the maximum foot workspace of walking leg, the numerical analytical and optimized method was applied with the help of Matlab. With the inverse kinematics equations, cycloid foot trajectory was generated and testified in the Adams software.2) After analyzing the motion patterns of quadruped mammal, a foot trajectory generator was presented on the basis of CPG. Aiming at satisfying robot’s demands of gait planning, an improved net-structure CPG data address generator was created, which had more advantages than traditional direct-function method, achieving all joints driving functions at same time. The startup gait was also planned.3) In order to evaluate the property of quadruped robot, Stability Margin(SM) was founded and improved by using the instant center of mass instead of geometric center. After deducting the critical stability factors, the influence of foot duty ratio and leg allocation on SM was debated and simulated. The ways to increase SM were put forward.4) To satisfy the growing needs on virtual prototype in designing quadruped bionic robot, computer aided software was developed on the basis of Adams soft. All editable mechanical and gait parameters were embedded in this redevelop software, combined with several friendly GUIs. One example with design and analysis process was introduced at last.