Slip Estimation in Planetary Rovers Using a Single-Wheel Testbed and Optical Flow Sensing

Planetary rovers play a crucial role in extraterrestrial exploration, enabling scientific investigations of planetary surfaces and subsurface materials. However, mobility on loose and deformable terrains, such as lunar regolith and Martian soil, poses significant challenges due to excessive wheel slip, which can lead to navigation errors, inefficient energy consumption, and potential entrapment. Accurate slip estimation is essential for enhancing rover autonomy and ensuring reliable traversal across diverse terrains. This paper presents a single-wheel testbed developed for slip estimation and analysis in planetary rovers. The testbed integrates multiple sensors, including encoders, load cells, and optical flow-based velocity measurement, to accurately quantify slip and study wheel-terrain interactions. Further, we demonstrate a slip estimation algorithm that identifies disparities in data from the wheel encoder and the on-board camera to accurately quantify slip. The algorithm is tested at different inclinations of the testbed to simulate slip conditions at higher inclinations. Our findings enhance slip estimation and compensation models, supporting future studies on machine learning-based slip prediction, adaptive control, and optimized wheel designs. This work advances planetary exploration by improving rover mobility and ensuring mission success on challenging terrains.