Transmissive optical pretouch sensing for robotic grasping

Robotic grasping has been hindered by the inability of robots to perceive unstructured environments. Because these environments can be complex or dynamic, it is important to obtain additional and precise sensing information just before grasping. This paper expands upon the pretouch modality by introducing a transmissive optical sensor. It can unambiguously indicate the presence or lack of objects in close proximity. A wide variety of items that other sensors fail to sense, such as extremely soft or shiny objects, can be detected by the proposed sensor. The sensor is also fully integrated into the fingertips of the PR2 robotic platform and manufactured with inexpensive, commercially-available components. Several experiments are conducted to verify its utility in both environment perception and robotic grasping. It is shown that the perception information supplied by the sensor facilitates effective robotic grasping.