Kinematic Synthesis and Analysis of Upper Limb Prosthetic Finger

The kinematics of a human finger is exceptionally designed to grasp objects of all sizes. The complexity and a large number of degrees of freedom within a small space gives it an ability to perform various gripping action. However, with the increasing number of cases of amputation, it becomes utmost necessary to design a prosthetic finger with kinematics as similar as of human hand, which is easy to design and affordable to the commons. This paper presented a simple way to design kinematics of prosthetic finger. Firstly, it explains a way to calculate the length of different links and links angles to verify as if the configuration is working as like that of a normal finger with validation from CAD tools. The designed finger can achieve complete flexion position from the fully extended position at a speed 90 degree per second. Our finger has one degree of freedom and works on the principal of the four-bar linkage mechanism. A 3d printed prototype model was tested experimentally and results are demonstrated. Secondly, With the purpose of further validation and to check the effectiveness of the mechanism, kinematic analysis based on position, velocity and acceleration of links has been carried out with respect to the time. The equation has been derived for each one of the above before the beginning of the analysis. Moreover, the trajectory of fingertip motion has been obtained from the motion simulation to observe the similarity in the action of the prosthetic finger with the human finger.