Abstract: The composition, scheme and principle of the stereo vision hazard avoidance technology for Tianwen 1 are introduced. Automatic selection of safe landing sites during the landing has been finished by image disturbance recognition and stereo terrain perception. High resolution stereo matching and sub pixel interpolation are used to improve the accuracy of long range stereo measurement. And limited by the computing resource, the FPGA is chosen as a hardware acceleration platform, and the speed of calculating parallax as well as 3D information are improved by the parallelization and pipeline design of the function module. To overcome the changes of parameters caused by the harsh environment on orbit, self calibration method is designed to update the stereo correction parameter table. The algorithm verification and on orbit applications have been carried out and the effectiveness of this technology has been verified. The 2K×2K high resolution dense stereo matching is realized by taking 1 s and the accuracy of 3D topographic survey and slope recognition reaches up to 6.7 cm@70 m and 0.5°, respectively. The system has successfully finished the on orbit self calibration, and the on orbit images can effectively restore the 3D terrain of the landing area.

Key words: Tianwen 1 lander, Stereo vision hazard avoidance system, FPGA, Stereo matching