Mechanical structure design and locomotion control framework for a wheeled hexapod rescue device

This paper presents the mechanical design and hierarchical locomotion control framework of a wheeled hexapod rescue device for disaster-rescue applications. Each wheel-leg adopts a Stewart-structured hybrid mechanism that integrates electric actuation with passive pneumatic transmission, providing multi-degree-of-freedom adjustment for terrain adaptation while supporting payloads with reduced energy demand. A compound power system and an onboard mechanical arm are further integrated to support long-duration operation and rescue manipulation tasks. For wheel-leg motion, a force-position hybrid controller with an admittance outer loop is developed to achieve compliant interaction and accurate trajectory tracking. For whole-body stability, an adaptive model predictive control strategy is established for body-attitude regulation based on rigid-body dynamic analysis and state-dependent reference generation. The mechanical arm is controlled through kinematic modeling and constrained optimization. Experimental results, including energy-efficiency evaluation, terrain-adaptation tests, terrain-traversal trials, teleoperation experiments, and field applications, demonstrate the effectiveness of the proposed system in rescue-oriented locomotion and manipulation tasks.