A positioning method of Chang´E-3 Rover in large-span states based on cylindrical projection of images

After bearing off from the Lander on December 15, 2013, the Chang´E-3 “Yutu” Rover starts its three-month exploration journey around the lunar surface. During the exploration journey, the “Yutu” Rover should acquire its own position and orientation in time so that it can reach the target to be probed and accomplish the detection tasks, which depends on high-precision positioning and navigating methods. This paper presents the technical details of positioning and navigating method of “Yutu” Rover, which is implemented by an integrated bundle adjustment system incorporating the cylindrical projection of sequential images and the calibration parameters of binocular cameras. The cylindrical projection of sequential images in the current station contains a larger overlapped region with that in the last station than a single image, and it includes more abundant feature points for the matching of large-scale transformative images. Thus, the rover in large-span states can be positioned by constructing bundle adjustment models with the matched feature points and the calibration parameters of binocular cameras. The positioning method has been successfully applied to the lunar exploration of “Yutu” Rover and has a good performance in guiding the movement of the “Yutu” Rover.