A Stair-Climbing Wheelchair with Novel Spoke Wheels for Smooth Motion

With the aging population and rising demand for assistive devices, electric wheelchairs have garnered significant attention. However, existing stair-climbing wheelchairs often suffer from complex structural complexity and limited flexibility. Spoke-wheel mechanisms, known for their simple structure and strong obstacle-crossing capabilities, hold promise but experience oscillation on flat terrain. This paper proposes an improved spoke-wheel mechanism (Flexwheel), which integrates springs into the spokes. These springs compress to varying lengths under gravitational force during ground contact, while sliding grooves and pre-compression constraints regulate spoke length, ensuring a stable height. A novel selection method for the optimal spring constant is developed based on mass, spoke length, and the number of spokes. This mathematical framework is applicable to stable, smooth ground motion under varying friction conditions between the upper and lower spokes. A wheelchair prototype equipped with four Flexwheels, a self-balancing mechanism, and multi-sensor fusion technology is designed. The simulation results indicate that Flexwheel reduces the range in body height from 10.75 mm (traditional spoke wheels) to 3.39 mm on flat terrain, a 68.47% improvement. During stair climbing, Flexwheel significantly reduces body oscillation compared to traditional spoke or circular wheels. Physical experiments validate that Flexwheel exhibits a 6.28 mm height fluctuation vs. traditional spokes wheels’ 12.13 mm, a 48.28% improvement, demonstrating its effectiveness in enhancing wheelchair stability and adaptability.