Running up a wall: the role and challenges of dynamic climbing in enhancing multi-modal legged systems.

Animals have demonstrated the ability to move through, across and over some of the most daunting environments on earth. This versatility and adaptability stems from their capacity to alter their locomotion dynamics and employ disparate locomotion modalities to suit the terrain at hand. As with modalities such as running, flying and swimming, dynamic climbing is commonly employed by legged animals, allowing for rapid and robust locomotion on vertical and near-vertical substrates. While recent robotic platforms have proven effective at anchoring reduced-order, dynamic climbing models, its adoption as a common modality for multi-modal, legged platforms remains nascent. In this work, we explore several of the open questions related to the physical implementation of dynamic climbing, including investigation of substrate inclinations for which dynamic climbing is suited, mitigation of destabilizing out-of-plane dynamics and improvement of attachment reliability in the presence of dynamic effects. The results from these inquiries provide several mechanisms and approaches for increasing the reliability and versatility of dynamic climbing as a dynamic legged modality. With these and other developments into legged locomotion modalities, future multi-modal platforms will begin to approach the expertise of biological creatures at moving through a complex and challenging world.