IMPROVING THE LOCALIZATION IN THE DOCKING PROBLEM OF THE VIBOT-2 MOBILE ROBOT

Abstract

This article presents a positioning solution for a mobile robot system, the Vibot-2 robot, in the docking problem where the robot must move backwards precisely to the charging position or the location to pick up the delivery cart (or return the cart) during the execution tasks. The localization system needs to calculate the robot's posture (including position coordinates and heading angle) in a fixed coordinate system attached to a fixed station with an accuracy within an allowable limit. The solution to build a positioning module for the Vibot-2 robot uses a stereo camera in combination with AprilTags mounted on a locator plate fixed at the station. Compared with the previous positioning solution applied to the Vibot-2 system, the proposed solution in this article changes the camera type and fiducial tag layout. Experimental results show that the new solution helps to increase the field of view of the positioning module by 30%, increase the measurement accuracy by more than 4 times in term of the average error in the horizontal axis, and at the same time, reduce the rate of measurements with errors outside the allowable limit in term of position by more than 1.5 times and in term of heading angle by more than 2 times.