Abstract
Tele-existence robots work in dangerous places while humans, which are operating them, are working in safe environments. In order to enable tele-existence robots to grasp or manipulate an object stably, obtaining tactile information and presenting the information to human is necessary. When a person grasps an object, the shearing strain is produced on the surface of the fingers. It is clear that the heavier the weight of the object, the larger the shearing strain becomes. To keep on grasping the object, he/she has to increase his/her grasping force according to the weight of the object. In order to make the tele-existence robot grasp something, the ability to detect the shearing strain is indispensable. As the shearing strain information is finally presented to the operator, the sensing ability of the robot needs to be as efficient as that of the operater. First, a psychophysical experiment was carried out to determine the human differential limen of shearing strain. The limen was found to be 200μm. Using this result, we designed a tactile sensor modelled after the human skin. Its sensing ability of shearing magnitude was 150μm and its shearing strain direction was 30 degree, which was superior to that of humans. The application of the sensor to a robot hand increased its effectiveness in adapting the robots grasp according to the varying weight of the object.
