Relationship between Force Modulation and Sensory Evaluation at Cylinder Grasp.

In order to clarify the grasping mechanism of tools and handles, we investigated, essentially, the finger joint pressures against cylindrical object and discussed the relatioship between the pressure change and sensory evaluation in grasping cylinder depending on load and diameter. During the grasp, finger joint pressures increased, transiently, immediately after loading and then decreased gradually to the stable pressure for 10 sec and after. The pressure at stable period was larger than the pressure at which the cylinder slipped down from the hand. The decline of finger joint pressures were slight during grasping the cylinder with high value sensory evaluation. But the tendency was weak during grasp with high load. The present results suggest that the mechanism under grasping depends on the load and the diameter of cylinder object. And the force modulation is consider to be influenced by the sensory evaluation for grasping.