Implementation Strategy of Visible and Near-Infrared Imaging Spectrometer on Yutu-2 Rover Based on Vision Measurement Technology

Abstract

Abstract. The Chang'e-4 successfully landed on the far side of the moon in January 2019. By the 12th lunar day, its Yutu-2 rover had achieved a breakthrough travel distance of greater than 300 m. A visible and near-infrared imaging spectrometer (VNIS), consisting of a visible and near-infrared (VNIR) imaging spectrometer and a shortwave infrared (SWIR) spectrometer was used for detecting mineralogical compositions of lunar-surface materials. Because VNIS is fixed on the front of the rover, and the field-of-view (FOV) of VNIR and SWIR are small (8.5° and 3.6° respectively), approaching and accurately pointing at the specific science target depend completely on the precise control of the moving rover.In this paper, a successful method of VNIS target detection based on vision measurement is proposed. First, the accurate position of the target is calculated via navigation camera imaging. Then, the moving path is planned by considering the terrain environment, illumination, communication condition, and other constraints. After the rover moves to the designed position, the binocular imaging of the hazard-avoidance cameras are activated, the detection direction and forward distance are calculated according to the images, and the FOV trajectory of the VINS is predicted while moving. Finally, by choosing the required moving control parameters, the imaging field of the VINS accurately cover the detected targets visually.These methods have been verified many times, and the results show that they are effective and feasible. The research results based on the VNIS data have successfully revealed the material composition on the far side of the moon and have deepened human understanding of its formation and evolution.

Applications of Photogrammetry and Remote Sensing Technologies in Chang’e-4 Mission

“…Photogrammetry and remote sensing technologies have been developed by several teams and greatly supported mission operations of the rover, e.g., terrain perception, hazard detection, path planning, rover localization and navigation, etc. (Liu et al, 2020;Wang et al, 2020;Yu et al, 2020;Di et al, 2020). The technologies and derived products have also directly supported various scientific investigations of the landing site, e.g., topographic evolution, crater morphologies, mineral composition of lunar deep materials, impact melt breccia, space weathering etc.…”

“…Navcam has the FOV of 46.6º and an image size 1024×1024 pixels. Hazcam is fixed on the lower front of the rover body with a baseline of 100mm; it has a FOV of 120º and an image size of 1024×1024 pixels (Yu et al, 2020).…”

“…Along the traverse, the rover obtains Navcam stereo images at every waypoint and acquires Pancam stereo images at some waypoints. These stereo images, with better than millimeter resolutions in near-range and centimeter resolutions in middlerange, have been routinely used in detailed topographic mapping and rover localization to support surface operations of the rover (Liu et al, 2020;Wang et al, 2020;Yu et al, 2020;Di et al, 2020).…”