High-Speed and Intelligent Pre-Grasp Motion by a Robotic Hand Equipped with Hierarchical Proximity Sensors

Abstract

Quickness, preciseness and robustness are required in manipulation tasks of robotic hands for automation of manufacturing sites. Previous researches have found that sensing from fingertips equipped with proximity sensors is available for the requirements, because it complements blind areas of vision sensors. In this paper, we develop a novel optical proximity sensor for robot fingertips which provides two levels of proximity information with different purposes, sampling rates, information quantity and quality. The lower-level information from the sensor is for high-speed feedback control of a robotic hand, and the higher-level information is for recognizing the shape and size of an object. A prototype of the sensor with 5 × 5 matrix of photo detectors is presented, and its availability is shown through basic characteristic tests. A motion experiment using a robotic hand equipped with the prototype sensors is also conducted. The result confirms that the robotic hand can adjust the position and orientation of the fingertips to various objects and then correct the grasping form according to the object size within 1s.