Design Of An Underactuated Prosthetic Hand With Adaptive Grasping Capabilities

An ideal prosthetic hand should not only have esthetic values, but also can replace ahuman hand to move and even to feel. Currently, the prosthetic hands in the domestic andforeign laboratories, however,are far from perfect.In order to make an anthropomorphicprosthetic hand with the capability of grasping things adaptively,the study is as follows.A novel under-actuated prosthetic hand is designed, the mechanicaldetails of whichiselaborated. This prototype is compact, anthropomorphic, and easy to control. This hand has15DOF by using only3motors one of which to control the thumb,while the others, twofingers respectively. The design of under-actuated tendon-driven fingers is introduced,followed by the introduction to themechanisms driving the differences, along with a couplingof geneva wheel and crank-slider mechanisms which are used to obtain3DOF of the thumb.Finally, this thesis introduces the appearance of the hand, as well as the ADAMS kinematicssimulation.The principles and organization of the mechanical system are analyzed. Based on theDSP, the movement control system is proposed with easy configuration, short-timedevelopment, and force feedback, which is applied to drive the motion of fingers. Thehardware and software of the system is introduced.The voltage changing circuit, sensorschosen and processing circuit, servo motor and linear motor chosen and communication withthe DSP of the armare enlisted in the hardware, while the flow diagrambelongs to thesoftwareThe grasping ability and mechanical property of the prosthetic hand are tested. The resultindicates that the prosthetic hand can meet daily demands, including the cylinder grasp,envelope grasp, precision grasp and literal grasp. Based on the functionality of the prosthetichand, high mechanical property is expected. Then some experiments are undertaken toevaluate the friction coefficient, the generalized grasping force, the literal force and the distalphalanges’ force of middle finger and index finger, so as to pinpoint the mechanical propertyof the hand, and pave way for the evolution of the mechanical design.