Dynamic Analysis and Performance Verification of a Novel Hip Prosthetic Mechanism

To assist an amputee in regaining his or her daily quality of life, based on analysis of the motion characteristics of the human hip, a 2-UPR/URR parallel mechanism with a passive limb was designed. The inverse kinematics of this mechanism was analyzed based on a closed-loop vector method. The constrained Jacobian matrix and kinematic Jacobian matrix of each limb were then analyzed, and a 6x6 fully Jacobian matrix was constructed. Based on this, kinematic performances were analyzed and summarized. Finally, the dynamic model of the mechanism was constructed based on the virtual work principle, and its theoretical solution was compared with the numerical results, which were obtained in a simulation environment. Results showed that the prosthetic mechanism had a larger rotating workspace and better mechanical performance, which accorded a range of motion and bearing capacity similar to that of the human hip in multiple gait modes. Moreover, the validity of the dynamic model and inverse kinematics were verified by comparing the theoretical and simulation results. Furthermore, with flexion and extension, the torque change in the hip prosthetic mechanism was similar to that of the human hip, which demonstrated the feasibility of the hip prosthetic mechanism and its good dynamic performance.