Compliant Footpads Enable Terrain‐Adaptive Hopping in a Monopedal Robot

Monopedal hopping robots offer exceptional mobility over discontinuous terrain but require consistent foot‐ground contact to maintain stance‐phase dynamics and prevent instability. This work presents a lightweight, compliant footpad that enhances the terrain adaptability of a hopping robot. The design combines a planar foot supported by a compliant spherical joint for self‐alignment with embedded spines to improve traction on uneven or slippery surfaces. Controlled drop tests demonstrate that the footpad preserves stance‐phase dynamics while reducing slipping and entrapment across rigid, granular, and soft terrains. Indoor trajectory tracking and outdoor experiments validate reliable hopping on grass, rocky trails, sand, and frozen ground, demonstrating that a simple yet effective compliant‐spined design can significantly expand the operational envelope of hopping robots in unstructured environments.