Dynamics Simulation For Hexapod Robot Based On Modeling Of Foot-terrain Interaction

NASA has just developed the All-Terrain Hex-Limbed Extra-TerrestrialExplorer “ATHLETE”, which is prepared for the exploration of moon and Mars.ATHLETE has perfect adaptability for rough terrain, and has redundancy functiondriver ability with42DOF, that shows the development potential to the world.Legged robots are different from the wheeled locomotive robot of traditionalconstruction. In the complex and rigorous terrain condition, they will play animportant role on traffic and planetary exploration with their unique advantage.Foot-terrain interaction is the only interaction interface between robot and theenvironment, which determines the moving features and carrying capacity of therobot. This paper conducted the study on the foot-terrain interaction model, anddeveloped dynamics co-simulation research based on the foot-terrain interactionmodel.This paper studied the foot-terrain model on the rigid environment. Whileestablishing the nonlinear stiffness-damping model between flexible feet and rigidground, the paper improved the Coulomb model on the tangential direction. Theparameter identification scheme was proposed and identification program wasfulfilled.This project also designed the experiment leg with flexible foot. With thesix-axis force/torque sensor, linear displacement sensor and data processing system,the paper built a testing platform for foot-terrain model. Taking advantage of thetesting platform, the paper completed the research of foot-terrain model andparameter identification.Based on the stress distribution theory in terramechanics, this paper deducedthe stress integral model in loosen geology. It proposed the compound nonlinearstiffness-damping model, and established the relationship between stress integralmodel and the compound nonlinear stiffness-damping model. Parameteridentification was accomplished utilizing the testing platform, and the completeanalytical expression was founded.Upon the foot-terrain model researched above, this paper wrote the secondarydevelopment program for the foot-terrain model with Fortran. The work created thedynamic link library for ADAMS. It also founded the co-simulation platformmaking use of Matlab/Simulink and ADAMS. With the simulation platform, thispaper achieved the dynamic simulation analysis for the hexapod robot based on thefoot-terrain model established above. Depending on the project research, this paper founded the complete foot-terraininteraction in rigid and loosen geological environment. Co-simulation platformoffered reference to structural design based on the foot-terrain interaction model,and provided a virtual verification platform for the multi-legged robot controlalgorithm with redundant actuation of multiple degrees of freedom.