Motion Control of a Hybrid Self-Reconfigurable Wheel-Legged Dual-Arm Robot

Current wheeled bipedal robots face significant mobility challenges when traversing discontinuous terrain such as gaps and step-like obstacles, and suffer from substantial dynamic inefficiencies. This paper presents a hybrid self-reconfigurable wheel-legged dual-arm robot equipped with an active docking mechanism, enabling transitions between wheeled bipedal and multi-wheel-legged configurations. Based on a self-developed robotic platform, this work addresses key control challenges in articulated multi-wheel-legged mode and proposes a novel distributed operation paradigm for wheeled bipedal robots. Each module utilizes its manipulators for stable grasping of elevated objects and collaborative tasks, while the multi-unit system achieves efficient, high-load, and stable locomotion. To manage the control complexities in multimodal operation, we develop a unified modular control architecture integrating Virtual Model Control (VMC) and Linear Quadratic Regulator (LQR). For the articulated multi-wheel-legged mode, a body-posture controller regulates global body configuration, and a turning controller adjusts the wheelbase and roll angle via distributed actuation to manage the passive degrees of freedom (DoF) at the articulation points. Experimental validation using a physical prototype confirms the effectiveness and practicality of the proposed approach.