EXPERIMENTS IN ROBOTIC SENSORIMOTOR CONTROL DURING GRASP

A series of experiments is presented, using a robot manipulator, which attempt to reproduce human sensorimotor control during grasping. The work utilizes a multifingered, dextrous robot hand equipped with a fin gertip force sensor to explore dynamic grasp force adjustment during m anipulation. The work is primarily concerned with the relationship bet ween the weight of an object and the grasp force required to lift it. Too weak a grasp is unstable and the object will slip from the hand. T oo strong a grasp may damage the object and/or the manipulator. An alg orithm is presented which reproduces observed human behavior during gr asp-and-lift tasks. The algorithm uses tactile information from the se nsor to dynamically adjust the grasp force during lift. It is assumed that there is no a priori knowledge about the object to be manipulated . The effects of different arm/band postures and object surfaces is ex plored. Finally, the use of sensory data to detect unexpected object m otion and to signal transitions between manipulation phases-with the c oincident triggering of new motor programs-is investigated.