Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: The In the Physiotherapy Division of the Faculty of Health Sciences on the Tygerberg
Hospital Campus of the University of Stellenbosch, the challenge arose to
develop a portable, affordable and yet accurate 3D measurement machine for the
assessment of posture in school children in their classroom environment. Currently
Division already uses a state-of-the-art VICON commercial medical measuring machine
to measure human posture in 3D in their physiotherapy clinic, but the system
is not portable and is too expensive to cart around to different places for testing.
To respond to this challenge, this Master’s thesis designed and analyzed a machine
and its supporting system through both research on stereo-vision methodologies
and empirical appraisal in the field. In the development process, the research
was required to overcome the limitations posed by small image resolutions and
lens distortions that are typical of cheap cameras. The academic challenge lay in
the development of an error prediction model through Jacobian derivation and Error
Propagation Law, to predict uncertainties of angular measurement calculated
by the system.
The research culminated in a system that is comparable in accuracy to the VICON
within 3mm, and that has 1.5mm absolute accuracy within its own system for a measurement volume radius of 2.5 m. As such, the developed error model is
an exact predictor of the angular error to within 0.02° of arc. These results, for both
system accuracy and the error model, exceed the expectations on the basis of the
initial challenge of the system.
The development of the machine was successful in providing a prototype tool
that is suitable for commercial development for use by physiotherapists in human
posture measurement and assessment.
In its current incarnation, the machine will also serve the Engineering Faculty
as the most fundamental form of a three-dimensional measuring apparatus using
only basic theories and algorithms of stereo-vision, thereby providing a basic
experimental platform from which further scientific research on the theory and application
of computer vision can be conducted. / AFRIKAANSE OPSOMMING: Die Fisioterapie Afdeling van die Fakulteit Gesondheidswetenskappe op die Tygerberg
kampus van die Universiteit van Stellenbosch gebruik ’n allernuutste VICON
kommersiële mediese meettoestel om menslike postuur in drie dimensies te
meet.
Vanuit hierdie Afdeling het die uitdaging ontstaan om ’n draagbare, bekostigbare,
maar tog akkurate, drie-dimensionele meetapparaat geskik vir die meet van
die postuur van skoolkinders in die klaskamer te ontwikkel.
In aanvaarding van hierdie uitdaging, het hierdie Magistertesis ’n toestel en
ondersteuningstels ontwerp en ontleed deur beide navorsing in stereo-visie metodiek
en terplaatse beoordeling. In die ontwikkelingsproses moes die navorsing die
beperkings wat deur klein-beeld resolusie en lens-distorsie (tipies van goedkoop
kameras) meegebring word, oorkom. Die akademiese uitdaging lê in die ontwikkeling
van ’n voorspellende foutmodel deur van die Jacobianse-afleiding en die Fout Propageringswet gebruik te maak om onsekerheid van hoeksberekening deur
die stelsel te voorspel.
Die navorsing het gelei tot ’n stelsel wat binne 3mm vergelykbaar is in akkuraatheid
met dié van die VICON en ook 1.5mm absolute interne akkuraatheid
het in ’n meet-volume radius van 2.5m radius. Die ontwikkelde foutmodel is dus
’n presiese voorspeller van hoekfout tot binne 0.02° van boog. Die resultate met
betrekking tot beide die akkuraatheid en die foutmodel het die oorspronklike verwagtinge
van die uitdaging oortref.
Die ontwikkeling was suksesvol in die skep van ’n prototipe-toestel geskik vir
kommersiële ontwikkeling, vir gebruik deur fisioterapeute in die meting en evaluering
van menslike postuur.
Die stelsel is in sy fundamentele vorm, deur die gebruik van slegs basiese teorieë
en algoritmes van stereo-visie, funksioneer as ’n drie-dimensionele meetapparaat.
In die fundamentele vorm sal die stelsel die Ingenieursfakulteit dien as ’n
basiese eksperimentele platform waarop verdere wetenskaplike navorsing in die
teorie en toepassing van rekenaar-visie gedoen kan word.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/6764 |
| Date | 03 1900 |
| Creators | Van der Westhuizen, Gareth |
| Contributors | Schreve, K., University of Stellenbosch. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 115 p. : ill. |
| Rights | University of Stellenbosch |
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