Biologically Inspired Grasp Primitives for a Dexterous Robotic Hand to Catch and Lift a Sphere

Joint motion profiles from nine human test subjects were recorded while catching and lifting a sphere. Significant differences between the two tasks presented themselves consistently across all test subjects. In general, larger abductions and hyperextensions of the metacarpophalangeal joints were observed. The joint motions of the test subjects were simulated in Simulink with a skeletal structure of the human hand. From the recorded motions, cubic polynomials were fit to the joint angle data to form two distinct grasp primitives. Simulations of these primitives were performed in Simulink with a skeletal structure of the Shadow Hand. These primitives were subsequently used on the physical system by a human operator who was able to pick up and catch a sphere with the Shadow Hand. An electromyogram signal measured from the forearm of the test subject was used as the input to the Shadow Hand controller. The sphere was successfully caught on five out of seven attempts with no prior practice with the system. The sphere was successfully lifted in seven of twelve attempts.