Design and Control of a Hexapod Robot RENS H3 for Lateral Walking on Unknown Rugged Terrains

Abstract

Legged robots provide an efficient alternative for navigation in complex terrains. However, few studies have explored dynamic locomotion for hexapod robots navigating unknown, rugged terrains. In this paper, the design, control, and implementation of a hexapod robot, RENS H3, inspired by the lateral movement of crabs, are presented with a focus on its adaptability in unknown, uneven terrains. The robot's structural design is introduced, and a hardware control framework for hexapod robots is developed. Additionally, a hierarchical control framework based on model predictive control is proposed, integrating terrain-adaptive control and foot-end Cartesian space force compensation based on posture adjustment into the control architecture to enhance the robot's robustness and terrain adaptability on slopes and unstructured terrains. The proposed method's robustness, adaptability, and energy efficiency were demonstrated through a series of experiments conducted on various outdoor slope terrains, unstructured terrains, and the multi-terrain testbed. Comparative experimental tests further validated the advantages of the approach in unknown rugged terrains.