Adaptive Spoke Design for Enhanced Mobility of Rimless Wheels on the Scout Rover

Abstract

Planetary exploration missions demand robust locomotion systems to traverse harsh terrain. Unlike traditional rovers, the German Aerospace Center (DLR) SCOUT rover employs rimless wheels specifically designed for extreme environments such as Martian caves, steep slopes, and rocky surfaces. This study presents a redesigned spoke geometry addressing limitations of earlier iterations, which were affected by premature fatigue and suboptimal climbing dynamics. The new design incorporates tapered, three-dimensional spokes forming an elliptical profile, intended to improve energy storage, traction, and self-righting capability, while reducing the effective footprint and protecting rover modules. Additional modifications, including an enlarged interface for the flexible feet, limit excessive bending under high loads, thereby preserving structural integrity and stability. Preliminary experiments, including an end-to-end demonstration in a lava tube, indicate that the adaptive spoke design maintains overall driving performance, while suggesting a potential improvement in spoke durability. A comprehensive test campaign will be required to confirm these findings.