MOBIUS: A Multi-Modal Bipedal Robot that can Walk, Crawl, Climb, and Roll

This paper presents the MOBIUS platform, a bipedal robot capable of walking, crawling, climbing, and rolling.MOBIUS features four limbs, two 6-DoF arms with two-finger grippers for manipulation and climbing, and two 4-DoF legs for locomotion-enabling smooth transitions across diverse terrains without reconfiguration.A hybrid control architecture combines reinforcement learning for locomotion and admittance control enhanced for safety by a Reference Governor and auto-tuning toward compliant contact interactions during manipulation.A high-level MIQCP planner autonomously selects locomotion modes to balance stability and energy efficiency.Hardware experiments demonstrate robust gait transitions, dynamic climbing, and full-body load support via pinch grasp.Overall, MOBIUS demonstrates the importance of tight integration between morphology, high-level planning, and control to enable mobile locomanipulation and grasping, substantially expanding its interaction capabilities, workspace, and traversability.