Abstract
It is considered that a person grasps an object efficiently by utilizing a critical force such that the object does not slip in the hand, and that regulation of the ‘grasp force’ based on slip information is useful for grasp control. Various slip sensors have been proposed for grasp control. Because many of the slip sensors and force sensors used in robots have analogue outputs, they are prone to being affected by electrical noise. Therefore they often require amplifiers, low pass filters and A-D converters. On the other hand, a force sensor using quartz resonators is robust to electrical noise since the output in this case is a frequency shift. This type of force sensor also has quick response time, high sensitivity, high resolution and wide bandwidth. Information on the grasp force, grasp position and slip and its direction is important for grasp control. Detection of grasp force and grasp position was reported in my previous paper. In this paper, a method of detecting slip and its direction by quartz resonators is reported. A principle for detecting slip and its direction, the results of changes in frictional force under various contact forces and slip speeds, and slip direction derived from two components of a frictional force are shown. It is demonstrated that an individual slip and its direction can be detected using quartz resonators, and that quartz resonators are useful in constructing a robot sensor.
