Design and Multi-Modal Locomotion Control of a Compound Leg-Wheel Robot

Abstract

To harness the terrain adaptability of legged systems and the high-speed efficiency of wheeled platforms, this paper presents the design of a novel leg-wheel hybrid mobile platform intended for enhanced obstacle negotiation. The proposed system comprises six identical leg-wheel modules, each integrating a closed-chain mechanical leg with an independently driven wheel mounted at the tip. The platform operates in two distinct modalities: a pure leg mode and a leg-wheel composite mode. In the leg mode, locomotion is driven by crank motors, providing exceptional mobility across uneven terrain. Conversely, the composite mode utilizes both crank and pitch link motors to facilitate obstacle surmounting, while hub motors ensure high-efficiency propulsion. Comprehensive gait planning for both modes is conducted, accompanied by a detailed analysis of the platform’s obstacle-negotiation capabilities. Kinematic analysis and gait simulations validate the platform’s superior mobility and efficient obstacle-crossing performance under the dual-mode strategy. Prototype experiments further confirm the feasibility of the mechanical design, demonstrating significant proficiency in traversing obstacles. This research contributes a novel design exploration by serially combining a closed-chain leg mechanism with an actuated wheel. The adopted closed-chain architecture offers the distinct advantages of high foot clearance and a single degree of freedom (DoF), which are critical for achieving reliable and effective obstacle-surmounting capabilities.