A PRECISE VISUAL LOCALISATION METHOD FOR THE CHINESE CHANG’E-4 YUTU-2 ROVER

摘要

Precise localisation of the Yutu-2 moon rover plays an important role in path planning, obstacle avoidance and navigating to target features. To provide high-precision localisation information, a stereo bundle adjustment method using the theory of the unit quaternions is presented for the first time. To improve the precision and robustness of the proposed method, the rover's pose, from a visual odometry technique assisted by an inertial measurement unit and the rotation angles of the mast mechanism, is viewed as a pseudo-observation. A reasonable weighting strategy and a rational geometric constraint condition of the stereo cameras is also invoked. Experimental results demonstrate that the proposed method provides more accurate localisation results than either a bundle adjustment alone or a weighted total least-squares method. The proposed method has been successfully used in Chang'e-4 mission operations.