Rover navigation using stereo ego-motion

• Published in: Robotics and autonomous systems 2003-06, Vol.43 (4), p.215-229
• Main Authors: Olson, Clark F., Matthies, Larry H., Schoppers, Marcel, Maimone, Mark W.
• Format: Article
• Language: English
• Subjects: Mars rovers; Motion estimation; Robot navigation; Stereo vision
• ISSN: 0921-8890; 1872-793X
• DOI: 10.1016/S0921-8890(03)00004-6

Robust navigation for mobile robots over long distances requires an accurate method for tracking the robot position in the environment. Promising techniques for position estimation by determining the camera ego-motion from monocular or stereo sequences have been previously described. However, long-distance navigation requires both a high level of robustness and a low rate of error growth. In this paper, we describe a methodology for long-distance rover navigation that meets these goals using robust estimation of ego-motion. The basic method is a maximum-likelihood ego-motion algorithm that models the error in stereo matching as a normal distribution elongated along the (parallel) camera viewing axes. Several mechanisms are described for improving navigation robustness in the context of this methodology. In addition, we show that a system based on only camera ego-motion estimates will accumulate errors with super-linear growth in the distance traveled, owing to increasing orientation errors. When an absolute orientation sensor is incorporated, the error growth can be reduced to a linear function of the distance traveled. We have tested these techniques using both extensive simulation and hundreds of real rover images and have achieved a low, linear rate of error growth. This method has been implemented to run on-board a prototype Mars rover.