Optimizing the lever propelling system for manual wheelchairs

Abstract

The article concerns the optimization of manual wheelchairs with a lever propelling system. Lever-driven manual wheelchairs are a promising wheelchair group, however they still need to be improved in order to compete successfully with classic manual push rim-driven wheelchairs. Also, despite all manual wheelchairs human work efficiency during propulsion plays an important role, there is not enough research carried out that would focus on this problem regarding lever-driven wheelchairs. The research, presented in this paper, according to the authors' intention, is to make this knowledge gap smaller. The article describes an analytical optimization method for adjusting important lever-drive system parameters - levers length and its axis of rotation position - to individual human anthropometry. The method is based on experimental data regarding maximum human push capabilities acquired in another study. The optimized parameters' values were determined after assessment of maximum human expendable energy during a single work phase (pushing the levers). As a result of this study authors determined optimal levers length and their axis of rotation position for a 50 percentile French male. The carried out research shows also, that the suboptimal area for positioning the levers axis of rotation is relatively wide.