Tiny range image sensors using multiple laser lights for short distance measurement

Abstract

This paper presents very compact range image sensors for short distance measurement, which is suitable for robot hands, etc. Robot manipulation such as grasping is one of the applications that require a range image sensor to obtain threedimensional (3D) information of the target object. For such applications, it is necessary to avoid the occlusion by a robot manipulator or a robot hand while measurement, and it is effective to attach a sensor to the robot hand for the avoidance. For this aim, a range sensor that is small enough and can measure at the short distance is required. Two sensors are constructed in this paper: one uses a multi-slit laser projector and the other uses a multi-spot laser projector. A small laser projector and a small camera is combined and range images are obtained in real time using the principle of active stereo. Appropriate methods to obtain range image are proposed for both sensors, and especially for the one with a multislit laser projector, a method to use both disparity and the intensity of laser light image is presented. The effectiveness of the proposed sensors is verified through short-range object measurement experiments.