Development of Variable Wheels for Wheelchairs and Evaluation of Their Step-climbing Performance Using a Wheel Traction Device

Abstract

Abstract In 2021, the percentage of the population aged 65 years and higher was 9.6% of the total population, and this ageing population is expected to increase globally. According to Sustainable Development Goal 11, barrier-free urban areas are expected to increase as braille blocks and roadside boundary blocks are widely used. However, this may cause discomfort to wheelchair users or become an obstacle to running wheelchairs. In this study, we focused on improving the wheel-type mechanism of climbing steps, which exhibits the highest performance when driving on flat terrain, to ensure the smooth and safe movement of wheelchairs. Although a step-climbing robot with a wheel-type mechanism can climb high steps, it has a large body and involves complicated control. The large size of the machine renders its attachment to wheelchairs difficult, reducing the mobility and safety of existing wheelchairs. Therefore, we developed a wheel to maintain the advantages of existing wheelchairs and improve their step-climbing performance. The developed wheel comprises a ‘normal mode’ for running on flat ground and an ‘expand mode’ for climbing steps. The diameter of the wheel in the expand mode is larger than that in the normal mode to improve the performance when climbing steps. Additionally, a spring was attached to the ‘foot’, which was installed to widen the diameter for enhanced driving stability. The step-climbing performance of the developed wheels was experimentally evaluated. A device was fabricated to pull the wheel using manual power and a motor. The motor-driven experimental apparatus maintained a constant traction force, facilitating a quantitative evaluation. The experiment further indicated that the contact position between the step and foot affected the step-climbing performance. Therefore, the study findings provide insights into the enhancement of the wheel-type mechanism for its efficient implementation in wheelchairs, which can contribute to their ease of use.