Research On Control System Of Under-Actuated Prosthetic Hand

Human hand could provide a variety of motion functions, which is one of the most effective tools in our daily lives. However, diseases and accidents have caused a large number of people with hand amputations, who cannot live and work normally. A functional, safe and reliable prosthetic hand is an effective way to solve this problem. In this thesis, we design a kind of control system and strategy of an under-actuated prosthetic hand(X-hand), aiming to provide a prosthetic hand for the amputees. The main contributions of this thesis include:(1) By analyzing the motion law of the X-Hand, the general design scheme of the control system of the prosthetic hand was put forward. Then the precise model of the servo control system was established, which laid the theoretical foundation for grasping posture control and compliance control of the prosthetic hand.(2) The control strategy of the prosthetic hand was designed. The trajectory of the prosthetic hand in free space was generated from the actual movements of human hand joints. And the force based impedance control was introduced to achieve the stiffness control of the prosthetic hand in actuation space, such that the prosthetic hand is compliant when grasping objects.(3) An embedded control system was developed. The control and drive circuits were designed, and a PCB with high degree of integration was made, which made the hand self-contained. The development of embedded software was also completed.(4) In the developed prosthetic hand control system, the motor servo control experiment and grasp experiment were carried out respectively, and the results showed that the designed control system of the prosthetic hand meet the application requirements.