Quadruped Robot Kinematics And Dynamics Research

Quadruped robots, which have low requirement on working environment, possesssuch advantages as good environment adaptability, good mobility, good stability andlarge load capacity, etc. Structure design, kinematics model and dynamics model forquadruped robots are studied deeply and systematically in this thesis, research resultsare of great significance for increasing moving velocity, enhancing stability andenvironment adaptability of quadruped robots.Mechanism model of quadruped robot with sixteen actuating degrees of freedom,four passive degrees of freedom is designed, on basis of workspace analysis ofquadruped robot, the structure of the hydraulically actuated quadruped robot, in whicheach leg possesses three active degrees of freedom, is designed.By defining the coordinate systems and related parameters, analysis model of thequadruped robot mechanism is established. The forward kinematics analysis and inversekinematics analysis for supporting legs and swinging legs are conducted usinghomogeneous coordinate transformation method, and velocity analysis and accelerationanalysis for swinging legs are also conducted using Jacobian matrix.Aiming at trotting gaits of quadruped robot, using virtual legs to replace a pair ofdiagonal legs of quadruped robot, the trotting gaits are converted into one-foot gaits,and movement between legs of quadruped robot is decoupled. By using elastic legs ofvirtual spring loaded inverted pendulum (SLIP) models to replace massive articulatedlegs, influence of the movement of swinging legs on the dynamics model of quadrupedrobot is analyzed, movement of swinging legs and movement of body can be consideredas decoupled when the quadruped robot is in flight phase, movement of swinging legs,movement of body and movement of supporting legs can be considered as decoupled aswell when the quadruped robot is in stance phase, and simplified dynamics models offlight phase and stance phase of quadruped robot are established. According to themotion characteristics of quadruped robot under trotting gaits, through equivalentmotion substitution, combination body model is presented to further simplify thedynamics model of stance phase. Based on the simplified dynamics model of quadruped robot, dynamics equations of flight phase and stance phase are established based onLagrange’s equation.Simulation model of quadruped robot is established on Adams desktop, controlmodel is also established in Matlab/Simulink environment by applying controlalgorithm of quadruped robot with trotting gaits, and Matlab-Adams union simulation isconducted. Simulation results coincide with the results of dynamics analysis, and therationality and validity of the simplified dynamics model of quadruped robot areverified.