LORIS: A Lightweight Free-Climbing Robot for Extreme Terrain Exploration

Climbing robots can investigate scientifically valuable sites that conventional rovers cannot access due to steep terrain features. Robots equipped with microspine grippers are particularly well-suited to ascending rocky cliff faces, but most existing designs are either large and slow or limited to relatively flat surfaces such as walls. We present a novel free-climbing robot to bridge this gap through innovations in gripper design and force control. Fully passive grippers and wrist joints allow secure grasping while reducing mass and complexity. Forces are distributed among the robot’s grippers using an optimization-based control strategy to minimize the risk of unexpected detachment. The robot prototype has demonstrated vertical climbing on both flat cinder block walls and uneven rock surfaces in full Earth gravity.

I. Introduction

Climbing robots have the potential to explore steep cliff faces, caves, and microgravity environments of scientific interest throughout the solar system [1] –[4]. While wheeled rovers are typically limited to shallow slopes, robots equipped with microspine grippers (summarized in Table I) are capable of ascending steep rock faces using arrays of sharp hooks that catch on small asperities in the surface [5], [6]. The earliest microspine grippers were fully passive, relying on the weight of the robot to provide the necessary engagement force, and robots equipped with these grippers were designed to traverse relatively flat surfaces such as the walls of buildings [7] –[9].