A novel sensor for dynamic tactile information

We present a novel tactile sensor, which is useful for dextrous grasping with a simple robot gripper. The novel part consists of an array of capacitive sensors, which couple to the object by means of little brushes of fibers. These sensor elements are very sensitive (with a threshold of about 5 mN) but robust enough not to be damaged during grasping. They yield two types of dynamical tactile information corresponding roughly to two types of tactile sensors in the human skin. The complete sensor consists of a foil-based static force sensor, which yields the total force and the center of the two-dimensional force distribution and is surrounded by an array of the dynamical sensor elements. One such sensor has been mounted on each of the two gripper jaws of our humanoid robot and equipped with the necessary read-out electronics and a CAN bus interface. As first applications we describe experiments to evaluate the quality of a grip using the sensor measurements and a utility that allows to guide the robot arm on a desired trajectory with negligible force.