Classical robotic grasping approaches employ static behaviors: First the hand is maneuvered to the object, then the fingers are closed, and finally the hand is retracted from the scene with the grasped object. On the other hand, humans execute wrist movements concurrently with the fingers closure. They also demonstrate higher performance in terms of stability. I therefore hypothesize that this coordination of wrist and hand would enable robust robotic grasping.
Description of Work
To evaluate this hypothesis, I conducted an experiment with seven human subjects grasping a set of seven objects using a robotic hand. The subjects guided the robotic hand with a handle and closed the fingers at will. I used a compliant robotic arm to limit the subjects’ control of wrist movement to different extents in five experimental conditions.
I observed that with increasing impairment, success rates decrease and less objects can be grasped reliably. This result supports the hypothesis that robust robotic grasping depends on coordination. To evaluate the role of wrist movement, I categorized the coordination patterns based on object types. Interestingly, thereby was found that exploitation of environmental constraints is capable of relaxing coordination requirements.
Finally, I demonstrate the transferability of the findings to robotic applications by implementing one of the observed coordination patterns on the robot. With this strategy, I was able to extend the robot’s capabilities in comparison to a simple top down grasp.