Kinematic transmission property of a novel mechanical humanoid leg

JI Shi-ming， LIU Yi， LI Yan-biao， LI Jing-min
（Key Laboratory of Special Purpose Equipment and Advanced Processing Technology，
Zhejiang University of Technology， Hangzhou 310032， China）

Abstract： Aiming at the problems of high moment inertia，low bearing capacity and can't meet the requirements of motion characteristics of humanoid robot of serial mechanism used in the current mechanical humanoid legs，a novel parallel mechanical humanoid leg was proposed，and the layout feature of a parallel humanoid mechanical leg was described. The inverse position equation of this mechanism was established. Based on this equation，the analytic expressions for the linear and angular velocity of the Jacobian matrix were derived by using the Vector method. Condition number and maneuverability of the two matrices were defined as the kinematics performance index to evaluate the kinematic transmission. At last，the distribution of the evaluation index was drawn out on the workspace respectively. The results indicate that kinematics performance of the foot is almost not affected by the movement of keen joint. The structure has three degrees of freedom and has the motion function of the ankle joint and keen joint. Simulation results meet the requirements of joint mechanics in human walking，which can provide a new configuration for the study of humanoid mechanical leg.
Key words： humanoid robot； parallel mechanical leg； kinematics performance index； workspace