Utilizing Sensed Incipient Slip Signals for Grasp Force Control
STANFORD UNIV CA CENTER FOR DESIGN RESEARCH
Pagination or Media Count:
We present a scheme by which a manipulator can identify when it is about to lose hold of a grasped object so that it can take preventive measures to maintain the grasp before slipping occurs. By detecting localized slips which precede gross slip between the gripping surface and a grasped object, a controller can reliably modify the grasp force and prevent the object from slipping. The motivation behind our sensor design comes from current physiological research which reveals the importance of a textured gripping surface in detecting these localized, or incipient, slips and provides us with insight into human grasping and manipulation strategies. By using our sensor as an active gripping surface on a simple manipulator and modeling our control strategy after humans, we are able to dynamically control the amount of force used to grasp objects, while preventing them from slipping. Our results show that the sensor is no greatly affected by variations in the material properties of the grasped object and indicate that the force control strategy is adequately immune to mechanical vibrations in the manipulator.