Simple off-line Odometry Calibration of Differential Drive Mobile Robots

Abstract

Odometry is a widely used method for estimation of the momentary pose of a mobile robot with respect to its starting pose. It provides easily accessible real-time pose information between periodic absolute pose measurements or between pose corrections using additional sensors. Odometric localization accumulates errors in an unbounded fashion with quadratic increase of error variance with traversed distance. Odometry errors consist of systematic and non-systematic parts. While non-systematic errors cannot be predicted and therefore compensated, systematic errors can be compensated by means of calibration, which can be off-line and on-line. This paper describes an approach to off-line odometry calibration for differential drive mobile robots, which is based on simple experiments combined with optimization methods. Two variants of the proposed calibration method are examined: one with 3 calibration parameters and other one with 2 calibration parameters. Experimental results obtained using Pioneer 2 DX differential drive mobile robot show that both methods significantly increase accuracy of the pose estimation. Due to simplicity and suitability for later on-line adaptation, calibration method with two parameters is preferred.