SUBJECT: Ph.D. Dissertation Defense
BY: Morris Huang
TIME: Thursday, September 21, 2017, 11:00 a.m.
PLACE: EBB, 5029
COMMITTEE: Dr. Stephen H. Sprigle, Chair (ME)
Dr. Aldo A. Ferri (ME)
Dr. Jun Ueda (ME)
Dr. Young-Hui Chang (BS)
Dr. Maysam Ghovanloo (ECE)
Dr. Mark Greig (Sunrise Medical)


The current approach to manual wheelchair design lacks a sound and objective connection to metrics for wheelchair performance. Wheelchair performance directly impacts propulsion effort, which is a strong determinant of user health and mobility. The objective of this thesis is 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. To this end, this defense presents the development of 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. Using this collection of devices, I demonstrate the variance manifested in the resistive properties of 8 casters and 4 drive wheels, and the impact 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, I define two empirical models linking system propulsion cost to component resistive properties. The outcomes of this research empower clinicians and users to make a more informed choice in wheelchair selection by means of a standard, scientifically-motivated performance metric. Furthermore, the empirical models offer manufacturers a basis by which to optimize their future wheelchair designs, thus motivating a better product for all wheelchair stakeholders.