2-UPS/RR parallel mechanism used in human hip joint power assist and kinematic performance

To help patients with impaired hip joint walking exercise, a 2-UPS/RR parallel mechanism was presented, which is suitable for hip joint assisting. It meets the requirements of hip movement for flexion/extension adduction/abduction, pronation/supination, and its mechanism centres of rotations accurately match different patient's hip. The mobility of the mechanism was calculated, inverse kinematics was solved by using the analytical method, and the velocity Jacobian matrix was established. By demarcating the driving parameters, the work space of the mechanism was coped with. Finally, in view of the Jacobian matrix, the kinematics performance of the mechanism was analyzed when driving mobile deputy and two axes of Hooke deputy, respectively. Results show that the mechanism is of favourable operability, flexibility and stiffness characteristics within the specified workspace. Compared wtih some existing hip joint power assist robots, the mechanism in simple structure can effectively avoid unnecessary interference between branches and significantly reduce the occupancy volume of the entire unit, absolutely with more advantages. Therefore, the designed mechanism is suitable for hip assist training.