Vertical Climbing Experiment of Four-Legged Rock-Climbing Robotwith Grasping Force Compensation in Rugged Wall

Abstract

This paper presents a multi-legged rock-climbing robot for surface exploration of rugged, steep terrains, such as a cliff wall. For a robot hand toward robotic rock-climbing, passive grippers with sharp spines at the tips of their fingers have been developed. The grippers need to be locally-adaptable to micro-scale roughness of the uncertain terrain and to exert sufficient grasping forces for climbing. In this paper, we propose two grasping force compensation functions for the gripper, tracing grip and tolerance to drawing back the gripper, using a force sensor attached to the wrist part. These functions can achieve the adaptability to the grasping the uncertain rugged terrain surfaces. The effectiveness of the proposed compensation functions was verified through vertical climbing experiments of a teleoperated four-legged rock-climbing robot system, which was newly designed and developed, in a rugged wall. The results show that the developed robot system is capable of the vertical climbing in the rugged wall by re-grasping in response to the compensation based on the sensing data of the grasping state.