【Prosthetic Hands】03 First Generation - MCP Movement

    The dexterous finger movement enables humans to grasp various objects. Such dexterity originates from the coordination of multiple tendons under the skin. In many prosthetic hand projects, the movement of the DIP, PIP, and MCP are interconnected, but it is actually quite common for humans to independently move the MCP joint. Thus, to better mimic human hands, I attempted to add one more active degree of freedom to the MCP joint.

    I used linkages to move the MCP joint. Frankly speaking, I did not figure out which combination of linkages generated largest torque output. Instead, I simply drew linkages with different length and tried to find a feasible one through the CAD simulation. 

    This design yielded a problem. Because I used wire to drive the phalanges, to prevent the movement of MCP joint affecting the movement of the wire, I had to let the wire pass exactly the rotation axis of the MCP joint. Thee result, combined with the servo motor, is demonstrated above.