A New Standard: RHIDE versus conventional techniques in evaluating wheelchair propulsion related biomechanics

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Abstract

This thesis discusses the potential of the RHIDE system, a device designed to measure
in-field wheelchair handrim push characteristics. The research question is if the RHIDE
can accurately discriminate propulsion/recovery and determine contact/release angles. This
research question is answered by determining push time (τ ), contact angle (α), release angle
(β) and push time (∆) for each push. To validate the RHIDE, these biomechanics are
measured with two different systems, one being the RHIDE and the other being the MarkerLess and Machine Learning Vision System (MLVS). Validation is conducted using data
from an experiment comprising 12 wheelchair propulsion-related tests on an ergometer, with
variations in speed (S1 and S2) and resistance (R1 and R2). For every push, τ , α, β and
∆ are extracted with both systems and the reliability of the RHIDE is calculated using an
ICC(2,1) on absolute agreement of the biomechanics for all pushes. For τ , ICC values are
0.65 for S1R1, 0.88 for S1R2, 0.98 S2R1 and 0.96 for S2R2 therefore reliability is considered
moderate, good, excellent and excellent respectively. For α, ICC values are 0.67 for S1R1,
0.59 for S1R2, 0.56 S2R1 and 0.51 for S2R2 giving moderate reliability for all tests. The
β ICC values are 0.57 for S1R1, 0.34 for S1R2, 0.35 S2R1 and 0.26 for S2R2 giving poor
reliability for all tests except S1R1. At last, ∆ ICC values are 0.17 for S1R1, 0.52 for S1R2,
0.25 S2R1 and 0.14 for S2R2, giving poor reliability for all tests except S1R2. Overall,
the RHIDE is able to accurately discriminate propulsion/recovery phases. Touch/release
angles are not reliable between systems. There are two potential causes for this. Firstly,
the RHIDE could improve its accuracy by increasing sample rate, streamline data pathways
and the introduction of a calibration protocol. Secondly, both systems measure different
contact/release angles and are therefore not comparable in this matter.
Overall, RHIDE has the potential to occupy a unique position in wheelchair propulsion
analysis by enabling the measurement of daily activities. With RHIDE, it would be feasible
to (1) provide information about propulsion technique by supplying push/release angles and
push times and (2) offer insights into daily wheelchair use over extended periods.

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