The Design Of Quadruped Robot With Series-parallel Connection Leg

This paper puts forward a new kind of design scheme of quadruped robot what is usingthe new type of string and compound structure as a robot leg mechanism. The quadrupedrobot has some advantage, such as the movement speed, strong load capacity, good stabilityand fast response speed, high degree of modularity and so on.Based on five-bar linkage and four-bar linkage, the paper proposes a new type of parallelmechanism, as the leg mechanism of quadruped robot. Structure model of quadruped robothas been established, and configuration of this mechanism is described in detail. The inverseand positive kinematics is built and validated the positive solutions of position and theinverse solution. Based on the inverse solutions, the implicit function derivation method isbeen used to solve the speed transmission Jacobin matrix, and then analyses the singularityof the leg mechanism. Using the geometric method under the condition of length limits, thethree-dimensional map of workspace and the graphs of cross section are got. At the sametime, the diagrams of the workspace-size influenced by structure parameters are got. Thatdiagrams will direct the parameter selection of the mechanism.Based on the speed transmission Jacobin matrix, force Jacobin matrix is deduced. Definesthe isotropic performance index, the output speed performance index and the load abilityperformance indicators. And draws out the multiple sets of evaluation index in theworkspace of different cross section distribution. Defines the organization’s comprehensiveperformance evaluation index，and draws out the curves of these evaluation index influencedby structure parameters. That curves will provide reference for the selection of structureparameters.Aiming at the factors influencing the walking stability of quadruped robot, the center ofgravity and ZMP equation are exported, which reflects static stability and dynamic stability.After the stable walking condition formulated, the state of stable walking gait isprogrammed. Combined with the analysis and planning, According to the characteristics ofthe horse foot in step process, this paper plans a robot walking gait, and simulates thewalking gait and finally gets the corresponding input curve of motor and the stress of themotion pairs. The conclusion provides some reference for the following research.