AN INDOOR LOCALIZATION METHOD FOR MOBILE ROBOT USING CEILING MOUNTED APRILTAGS

Abstract

Localization is one of the most important functions for autonomous mobile robots (AMRs). For indoor applications, the localization problem faces some difficulties such as lightning variation, dynamic objects or highly reflective surfaces that generate measurement noises for the perceptive sensor systems. Recently, tags-based pose estimation has become a popular and efficient solution for AMRs. In this article, we also ultilize ceiling mounted AprilTags for our AMR application in indoor environment. The advantage of AprilTags is their invariance to uncertainty of the environment such as lightning conditions, providing robust pose measurements with a fairly large range of measuring distances from the camera to fiducial markers. By integrating AprilTags in the SLAM package, we have solved several problems such as robot pose-recovery problem and improving the accuracy of the robot localization. Experiments with an AMR robotic system, the Vibot-2 robot, are carried out in two cases: under day-light condition and night-time condition to verify the accuracy of the method. In addition, we also discuss our solution of tag positioning in order to increase the stability of the robot navigation in global map. Experiment results show that the accuracy in pose estimation is less than 20 cm in terms of position and less than 5° in terms of heading angle. Furthermore, the pose measurements from the camera are quite stable under different lightning conditions.