A Study on Terrain Slope Estimation using an Infrared Camera for Planetary Exploration Rovers

Abstract

In recent years, planetary surface exploration missions by rovers have been actively performed. Rovers are required to recognize the surrounding environment autonomously for an efficient and safe exploration. Above all, terrain slope estimation is one of the essential techniques, which is conventionally performed with stereo cameras or shape-from-shading techniques. However, those schemes have problems such as the degraded accuracy in low-textured terrain and the heavy computational cost. Therefore, this paper proposes a new method that uses the difference of surface temperatures between at and slanted surfaces. It is known that the difference of solar radiation generates the gap in surface temperatures, which can be remotely detected with an infrared camera. The proposed method estimates terrain tilt angles using the energy balance equation and a single thermal image from the infrared camera. The method is validated with a field experiment in Izu-Oshima island. The developed thermal-based technique potentially increases the applicability to various terrain types regardless of the terrain appearance.