(Georgia Institute of Technology, 2020-12-06)
Misch, Jacob P.
The current manual wheelchair design process lacks consistent and objective connection to performance-based metrics. The goal of this research was to empirically assess over-ground manual wheelchair performances and identify important design trade-offs through the use of a robotic apparatus with a novel cyclic propulsion control method. This research had four specific aims: 1) to design, implement, and validate torque-based propulsion to emulate the intermittent human propulsion cycle with an existing robotic wheelchair tester, 2) to investigate the influence of incremental mass additions to the wheelchair frame on over-ground propulsion characteristics, 3) to demonstrably improve the performance of a representative high-strength lightweight wheelchair by leveraging existing component-level test results, and 4) to characterize the mechanical performances of representative folding and rigid ultra-lightweight wheelchair frames. The outcomes of this research include an objective, repeatable, and validated test method to assess over-ground performances of manual wheelchairs in realistic contexts of use, as well as insight on the mechanics of the system that were previously under-studied or confounded by variabilities within human subject testing. Controlled propulsion tests are used to identify differences between wheelchair configurations. The outcome variable of propulsion cost represents the energetic requirements of propelling each chair a given distance and has direct relevance to manufacturers, clinicians, and wheelchair users alike. Ultimately, these outcomes will inform clinicians and manufacturers about how configuration choices influence propulsive efforts, which can be used in turn to improve their classification techniques and existing design processes. This knowledge will additionally empower wheelchair users to make informed choices during the wheelchair selection process based on objective mechanical performance metrics.
(Georgia Institute of Technology, 2017-11-10)
Huang, Morris
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.