Tendon-based Gripper

The pin hub shown above in light-gray houses three sets of radial locking pins and cam follower pins along with a compression spring that constantly applies a force radially outward. These radial pins engage with the holes in the center pulley (light-blue), rotating the entire assembly. As the assembly rotates, the torsion spring leg is displaced from its start position, adding tension to the torsion spring. Once the torsion spring leg reaches the end position after ~95°, the cam followers encounter the lobes of the face cam plates, retracing the radial pins inwards and disengaging the center pulley from the pin hub. The center pulley and pin hub are both press fit on a radial bearing, allowing the pulley to quickly rotate the back to the start position when disengaged. The pin hub only needs to rotate another ~25° before the pins re-engage with the center pulley, allowing the finger extension and retraction cycle to be repeatable.