Research On Prosthetic Wrist Based On Movement Function Repetition

Human hands are important for everyday life,both to feel the environment and to change the environment.The wrist plays an important role in the hand movement space and dexterity for adjusting hands position and posture.In order to meet the development of the prosthetic hands and the demands of its dexterity from amputees,supported in part by the National Basic Research Program(973 Program)of China(Grant No.2011CB013306),this paper launch a research on prosthetic wrist mechanism based on the method of humanoid movement function repetition.First of all,start the research on human wrist from the aspect of physiology,determine the wrist active range of motion and daily life range of motion,and put forward a wrist movement classification tree.In order to guide the subsequent design work,study prosthetic wrist movement function repetition and its realization,then the repetition rate of wrist function to daily life activities and the quantification of movement space coincidence based on HIT-IV prosthetic hand are proposed.Repetition rate is used to evaluate the retrieval ability of different wrist repetition pattern to daily activities,contributing to the comprehensive consideration of wrist function in wrist mechanism design.Movement space coincidence quantification can to some extent,reflect the personification of prosthetic hand and wrist mechanism,used to guide the wrist mechanism motion range design.Secondly,design the wrist mechanism,which includes a quick change interface between wrist and hand and a locking mechanism,based on the above method of movement function retrieval.The design idea and design criteria of the prosthetic wrist are proposed.Detailed design the wrist mechanism according to the design criteria,and puts forward 2.5 DOF configuration,this is rotation and flexion/extension is active degree while radial/ulnar deviation is a passive degree.Design the quick change interface between hand and wrist,it has stable mechanical properties and electrical connections,and can achieve rapid install or uninstall of different prosthetic hand.Design the locking mechanism,its overall size is small,and can achieve stable lock of wrist rotation and flexion/extension,and can bear large passive torque.Finally,set up a hand-wrist system experimental platform based on HIT-IV hand,and test the mechanical properties,movement properties,and practicability of the wrist mechanism.Validate the wrist mechanism locking performance,extreme movement range and hysteresis error.Verify the rotation and flexion/extension ability to complete independence action or compound action based on the proposed wrist movement classification tree.HIT-IV hand grasping ability of small and big object with wrist mechanism or not is carried on the experiment.The experimental results show that,the wrist mechanism designed in this task is feasible,the technical parameters meet the design requirements,can largely recover humanoid movement function.