Force and proximity fingertip sensor to enhance grasping perception

It is well known that tactile information can be used to enhance the quality of grasping. Therefore, new technological solutions for sensing in grasping are needed. This paper presents an optical based fingertip sensor that measures both interaction forces and proximity between fingertip and environment. The combination of multiple sensing modalities in the tip of a finger can significantly improve grasping and manipulation capabilities. In this work we present the design and the required calibration of individual sensing elements, and of the integrated fingertip sensor developed for a 3-fingered metamorphic robotic hand. Emulated grasping experiments, using a pinch grip, were performed to illustrate the concept and validate the performance of the developed sensing system. As a result, it was possible to determine the sensor position with respect to an object during approach, contact and grasp.