Development of a Visual Odometry System for a Wheeled Robot on Loose Soil using a Telecentric Camera

In this paper, the development of a 3-dimensional odometry system for wheeled robots on loose soil in an application of planetary exploration is described. When a wheeled robot operates in a slippery environment, visual odometry, which is used to obtain flow-images of the ground with a CCD camera, is effective for the measurement of motion because it is a non-contact method. However, in the target condition, a measurement result with a conventional camera is not reliable with this method because the viewing area of the ground varies as a result of the changing distance between the camera and the ground as a result of the wheels sinking in loose soil. To solve this problem, we used a telecentric camera for visual odometry whose lens keeps the same field of view with a change of distance between the camera and the ground. Using the camera, we developed a 3-dimensional odometry system for our mobile robot to enable its positioning and navigation, and we validated the system with several experiments. In this paper, a structure and a performance test of the developed system is described. After that, the results of experiments in indoor (sandbox) and outdoor (seashore) environments are introduced. keywords: mobile robot positioning, visual odometry, telecentric camera