Development of component and system level test methods to characterize manual wheelchair propulsion cost

Abstract

The current approach to manual wheelchair design lacks a sound and objective connection to metrics for wheelchair performance. The objective of this research was three-fold: 1) to characterize the inertial and resistive properties of different wheelchair components and configurations, 2) to characterize the systems-level wheelchair propulsion cost, and 3) to model wheelchair propulsion cost as a function of measured component and configuration properties. Scientific tools developed include 1) a series of instruments and methodologies to evaluate the rotational inertia, rolling resistance, and scrub torque of wheelchair casters and drive wheels on various surface types, and 2) a wheelchair-propelling robot capable of measuring propulsion cost across a collection of maneuvers representative of everyday wheelchair mobility. This suite of tools were used to demonstrate the variance manifested in the resistive properties of 8 casters and 4 drive wheels, and the impact/tradeoffs of these components (as well as mass and weight distribution) on system-level wheelchair propulsion cost. Coupling these findings with a theoretical framework describing wheelchair dynamics resulted in two empirical models linking system propulsion cost to component resistive properties. The outcomes of this research empower clinicians and users to make more informed wheelchair selections, as well as offer manufacturers a basis by which to optimize their wheelchair designs.