Research On Dynamics Simulation Of Heavy-load Six-legged Robot Based On Vortex

NASA has just developed the All-Terrain Hex-Limbed Extra-Terrestrial Explorer“ATHLETE”, which is prepared for the exploration of moon and Mars. ATHLETE hasperfect adaptability for rough terrain, and has redundancy function driver ability with42DOF, that shows the development potential to the world. Legged robots are differentfrom the wheeled locomotive robot of traditional construction. In the complex andrigorous terrain condition, they will play an important role on traffic and planetaryexploration with their unique advantage.With regard to heavy load hexapod robot, because of its mechanical structure has agreater mass, the impact to its structure is larger under the same motion condition, therobot’s foot end trajectory largely affect the smoothness of the robot’s movement andthe service life of the mechanical structure. This thesis designs a trajectory of the footend of the robot for the purpose of reduce the impact between the robot and terrainwhen starting and stopping moving, thus the impact of force and velocity when startingand stopping moving is zero. This thesis has also chosen two gaits for the need ofstraight walking and turning on the spot, and verified the stability of the gait by themethod of solving the stability margin of the robot while moving.Compared to kinematics-based position control and speed control, the force controlbased on dynamic has better flexibility, and this feature is particularly important forheavy-duty robot, this thesis starting from the kinetic analysis, established dynamicequations of the robot using the Newton-Euler method, and also studied the controlmethod based on the dynamics model, using fuzzy PID controller.Foot-terrain interaction is the only interaction interface between the robot and theenvironment, which determines the moving features and carrying the capacity of therobot. Software of dynamics in the market solutes for contact force using the method ofrigid-body collision theory, which does not applicable to this project. This thesisestablished a mechanics model to describe the contact force between by analyzing theprocess of the contact between the robot foot and the soft terrain, and verified itscorrectness experimentally. Dynamic simulation plays an important role in the process of a robot development;and can guide the design of the robot. Based on the software of Vortex, a dynamicssimulation platform of six-legged robot was build, the contact mechanics model and thecontrol method and algorithms based on the dynamic model are added into the platform.Using the platform, simulations are played and the motion which designed former hasbeen evaluated.