+publisher:"Stellenbosch University" +contributor:("Scheffer, C.") – OATD
You searched for +publisher:"Stellenbosch University" +contributor:("Scheffer, C."). Showing records 1 – 30 of 39 total matches.
1. Van Schalkwyk, Etienne P. Determining femoral component goodness-of-fit using computer segmentation and numerical simulation.
ENGLISH ABSTRACT: The c2 goodness-of-fit (GOF) test was used to determine which standard femoral component… (more)
ENGLISH ABSTRACT: The c2 goodness-of-fit (GOF) test was used to determine which standard femoral component would achieve the best geometrical fit for a specific patient. This was done by creating 3D models from computerized tomography scan data through computer segmentation using Materialise MIMICS. The second step was to measure the morphological dimensions of the distal femur whereof twelve were selected and compared to the dimensions of two commercial femoral prosthesis designs. Thirdly, cadaveric femurs were scanned with a 3D desktop scanner to create a database with the dimensions of healthy knees. The 3D model database of the cadaveric femurs included cartilage layer. A cartilage thickness was added to the CT knee dimensions using a self-organizing map (SOM) calculation based on the healthy knee database. The developed method calculated alignment angles with higher accuracy than presently used and determined preoperatively which size to implant. Kinematic simulations of total knee arthroplasty (TKA) knees were compared to normal knee simulations created in LifeMOD. The articulating surface was the only variable changed between the two simulations and the kinematics of different sizes were evaluated. A method was created to scale the femoral component using the standard available sizes. The completed project will be used as foundation for customization of TKA prostheses.
AFRIKAANSE OPSOMMING: Die c2 graad van passing toets metode was gebruik om te bereken watter standaard femorale komponent ’n patiënt die beste geometries pas. Dit was gedoen deur eerstens 3D modelle gemaak vanaf CT skandeer data deur rekenaar segmentasie met Materialise MIMICS. Daarna was morfologiese dimensies gemeet vanaf die distale femur, waarvan twaalf gekies en vergelyk was teen two kommersiële femorale prostesis ontwerpe. Laastens was kadawer femurs geskandeer met ‘n 3D skandeerder om ’n databasis van gesonde knieë te maak. Die 3D modelle van die kadawer bene het die kraakbeen laag bevat. Die kraakbeen dikte was by die CT knie dimensies gevoeg d.m.v. SOM en die gesonde knie databasis. Die nuwe metode bereken die belynings hoeke met hoër akkuraatheid as wat huidiglik gebruik word en bereken voor die operasie watter grote om te gebruik. Kinematiese simulasies van knie prostesis was vergelyk met ’n normale knie simulasies gemaak in LifeMOD. Die artikulêre oppervlakte was die enigste veranderlike tussen die twee simulasies en kinematika van verskillende grotes was ondersoek. ‘n Metode was geskep om die standaard femorale komponent se skaal te verander vir ’n beter passing.
Subjects/Keywords: Mechanical engineering; Knee prostheses
Van Schalkwyk, E. P. (2010). Determining femoral component goodness-of-fit using computer segmentation and numerical simulation . (Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/4320
Van Schalkwyk, Etienne P. “Determining femoral component goodness-of-fit using computer segmentation and numerical simulation.” 2010. Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/4320.
Van Schalkwyk, Etienne P. “Determining femoral component goodness-of-fit using computer segmentation and numerical simulation.” 2010. Web. 20 Feb 2019.
Van Schalkwyk EP. Determining femoral component goodness-of-fit using computer segmentation and numerical simulation. [Internet] [Thesis]. Stellenbosch University; 2010. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/4320.
Van Schalkwyk EP. Determining femoral component goodness-of-fit using computer segmentation and numerical simulation. [Thesis]. Stellenbosch University; 2010. Available from: http://hdl.handle.net/10019.1/4320
2. Christiane, Peter-John. Development of a minimally invasive robotic surgical manipulator.
Degree: MScEng, Mechanical and Mechatronic Engineering, 2009, Stellenbosch University
ENGLISH ABSTRACT: Minimal invasive surgery (MIS) enables surgeons to operate through a few small incisions made in the patient’s body. Through these incisions, long rigid… (more)
ENGLISH ABSTRACT: Minimal invasive surgery (MIS) enables surgeons to operate through a few small incisions made in the patient’s body. Through these incisions, long rigid instruments are inserted into the body and manipulated to perform the necessary surgical tasks. Conventional instruments, however, are constrained by having only five degrees of freedom (DOF), as well as having scaled and mirrored movements, thereby limiting the surgeon’s dexterity. Surgeons are also deprived of depth perception and hand-eye coordination due to only having two-dimensional visual feedback. Surgical robotics attempt to alleviate these drawbacks by increasing dexterity, eliminating the fulcrum effect and providing the surgeon with three-dimensional visualisation. This reduces the risks to the patient as well as to the surgeon. However, existing MIS systems are extremely expensive and bulky in operating rooms, preventing their more widespread adoption. In this thesis, a new, inexpensive seven-DOF primary slave manipulator (PSM) is presented. The four-DOF wrist is actuated through a tendon mechanism driven by five 12 VDC motors. A repeatability study on the wrist’s joint position was done and showed a standard deviation of 0.38 degrees. A strength test was also done and demonstrated that the manipulator is able to resist a 10 N opposing tip force and is capable of a theoretical gripping force of 15 N.
AFRIKAANSE OPSOMMING: Minimale indringende chirurgie (MIC) maak dit vir chirurge moontlik om operasies uit te voer deur ’n paar klein insnydings wat op die pasiënt se liggaam gemaak word. Deur hierdie insnydings word lang onbuigsame instrumente in die liggaam ingesit en gemanipuleer om die nodige chirurgiese take uit te voer. Konvensionele instrumente is egter beperk vanweë die feit dat hulle net vyf vryheidsgrade het, asook afgeskaalde bewegings en spieëlbewegings, en gevolglik die chirurg se handvaardigheid beperk. Chirurge word ook ontneem van dieptewaarneming en hand-oog-koördinasie, want hulle is beperk tot tweedimensionele visuele terugvoer. Chirurgiese robotika poog om hierdie nadele aan te spreek deur handvaardigheid te vermeerder, die hefboomeffek uit te skakel en die chirurg driedimensionele visualisering te bied. Dit verminder die risiko’s vir die pasiënt én vir die chirurg. Bestaande MIC-stelsels is egter uiters duur en neem baie plek op in teaters, wat verhoed dat hulle op ’n groter skaal gebruik word. In hierdie tesis word ’n nuwe, goedkoop sewevryheidsgrade- primêre slaafmanipuleerder (PSM) voorgelê. Die viervryheidsgrade-pols word beweeg deur ’n tendonmeganisme wat aangedryf word deur vyf 12 VDC-motors. ’n Herhaalbaarheidstudie is op die pols se gewrigsposisie gedoen, wat ’n standaardafwyking van 0.38 grade aangetoon het. ’n Sterktetoets is ook gedoen en het gewys dat die manipuleerder in staat is om ’n 10 N-teenkantelkrag te weerstaan en dat dit oor ’n teoretiese greepsterkte van 15 N beskik.
Advisors/Committee Members: Scheffer, C., Schreve, K., Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering..
Subjects/Keywords: Mechatronic engineering; Robotics in medicine; Endoscopic surgery
Christiane, P. (2009). Development of a minimally invasive robotic surgical manipulator . (Masters Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/4497
Christiane, Peter-John. “Development of a minimally invasive robotic surgical manipulator.” 2009. Masters Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/4497.
Christiane, Peter-John. “Development of a minimally invasive robotic surgical manipulator.” 2009. Web. 20 Feb 2019.
Christiane P. Development of a minimally invasive robotic surgical manipulator. [Internet] [Masters thesis]. Stellenbosch University; 2009. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/4497.
Christiane P. Development of a minimally invasive robotic surgical manipulator. [Masters Thesis]. Stellenbosch University; 2009. Available from: http://hdl.handle.net/10019.1/4497
3. Doll, Stefan. Development of a magnetic intra-uterine manipulator.
Doll, Stefan. “Development of a magnetic intra-uterine manipulator.” 2012. Masters Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/19935.
Doll, Stefan. “Development of a magnetic intra-uterine manipulator.” 2012. Web. 20 Feb 2019.
Doll S. Development of a magnetic intra-uterine manipulator. [Internet] [Masters thesis]. Stellenbosch University; 2012. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/19935.
4. Cloete, Garth. Non-invasive artificial pulse oximetry : development & testing.
Degree: MScEng, Mechanical, 2012, Stellenbosch University
ENGLISH ABSTRACT: The monitoring of patients in healthcare is of prime importance to ensure their efficient treatment. The monitoring of blood oxygen saturation in tissues… (more)
ENGLISH ABSTRACT: The monitoring of patients in healthcare is of prime importance to ensure their efficient treatment. The monitoring of blood oxygen saturation in tissues affected by diseases or conditions that may negatively affect the function is a field that has grown in importance in recent times. This study involved the development and testing of a highly sensitive noninvasive blood oxygen saturation device. The device can be used to continuously monitor the condition of tissue affected by diseases which affect the blood flow through the tissue, and the oxygen usage in tissue. The device’s system was designed to specifically monitor occluded tissue which has low oxygen saturations and low perfusion. With the use of the device, it is possible to monitor the status of tissue affected by diseases such as meningococcemia and diabetes mellitus or conditions such as the recovery after plastic surgery. The study delved into all aspects involved in the development of a non-invasive artificial pulse oximeter, including but not limited to that of a detailed device design, signals analysis, animal in-vivo and laboratory in-vitro system design for the calibration of the system as well as human clinical validation and testing procedures. All these aspects were compared to determine the relative accuracies of the different models. Through testing it was shown that it is possible to non-invasively measure the mixed oxygen saturation in occluded tissue. However, without accurate validation techniques and methods of obtaining both arterial and venous blood samples in occluded tissue the system could not be fully validated for determining both the arterial and venous oxygen saturations in the human invivo study. Although the system was unable to accurately measure specifically the venous oxygenation it was able to measure the mixed oxygen saturation. With further research it would be possible to validate the system for measuring both the arterial and venous oxygen saturations.
AFRIKAANSE OPSOMMING: Die monitering van pasiënte in gesondheidsorg is van uiterste belang om doeltreffende behandeling te verseker. Die monitering van bloedsuurstofversadiging in weefsels wat geaffekteer word deur siektes of toestande wat ’n negatiewe impak kan hê op die funksie daarvan is ’n gebied wat aansienlike groei getoon het in die onlangse verlede. Die studie het die ontwikkeling en toetsing van ’n hoogs sensitiewe nieindringende bloedsuurstofversadigingsensor ingesluit. Hierdie sensor kan gebruik word om deurentyd die toestand van weefsel te monitor wat geaffekteer word deur siektes wat bloedvloei deur weefsel affekteer sowel as die suurstofgebruik in die weefsel. Die stelsel is ontwerp om spesifiek die ingeslote weefsel wat lae suurstofversadiging en lae perfusie het, te monitor. Deur gebruik te maak van die toestel is dit moontlik om die toestand van die weefsel wat geaffekteer word deur siektes soos meningococcemia en diabetes mellitus of toestande soos die herstel na plastiese sjirurgie te monitor. …
Advisors/Committee Members: Scheffer, C., Stellenbosch University. Faculty of Engineering. Dept. of Mechanical & Mechatronic Engineering..
Subjects/Keywords: Mechatronic engineering
Cloete, G. (2012). Non-invasive artificial pulse oximetry : development & testing . (Masters Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/19947
Cloete, Garth. “Non-invasive artificial pulse oximetry : development & testing.” 2012. Masters Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/19947.
Cloete, Garth. “Non-invasive artificial pulse oximetry : development & testing.” 2012. Web. 20 Feb 2019.
Cloete G. Non-invasive artificial pulse oximetry : development & testing. [Internet] [Masters thesis]. Stellenbosch University; 2012. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/19947.
Cloete G. Non-invasive artificial pulse oximetry : development & testing. [Masters Thesis]. Stellenbosch University; 2012. Available from: http://hdl.handle.net/10019.1/19947
5. Cloete, Teunis. Benchmarking full-body inertial motion capture for clinical gait analysis.
Cloete, Teunis. “Benchmarking full-body inertial motion capture for clinical gait analysis.” 2009. Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/2922.
Cloete, Teunis. “Benchmarking full-body inertial motion capture for clinical gait analysis.” 2009. Web. 20 Feb 2019.
Cloete T. Benchmarking full-body inertial motion capture for clinical gait analysis. [Internet] [Thesis]. Stellenbosch University; 2009. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/2922.
6. Smit, Albert. Development of a robot for RoboCup Small Size League, utilizing a distributed control architecture for a multi-robot system development platform.
ENGLISH ABSTRACT: RoboCup promotes research in robotics and multi-robot systems (MRS). The RoboCup Small Size League (SSL), in particular, offers an entry level opportunity to… (more)
ENGLISH ABSTRACT: RoboCup promotes research in robotics and multi-robot systems (MRS). The RoboCup Small Size League (SSL), in particular, offers an entry level opportunity to take part in this field of study. This thesis presents a starting phase for research in robotics and MRS at Stellenbosch University. It includes the full documentation of the mechanical, electronic and software design of an omni-directional soccer robot for RoboCup SSL. The robot is also meant to operate as a hardware and software development platform for research in MRS. The platform was therefore designed with high-level programming language compatibility, a wide range of connectivity, and modularity in mind. The robot uses a single board computer (SBC) running a Linux operating system to accomplish these objectives. Moreover, a driver class library was written in C++ as a software application interface (API) for future development on the robot platform. The robot was also developed with a particular focus on a distributed control architecture. "Player" was implemented as the middleware, which can be used for communication between multiple robots in a distributed environment. Additionally, three tests were performed to demonstrate the functionality of the prototype: a PI speed control test, a direction accuracy test and a static communication test using the middleware. Recommendations for possible future work are also given.
AFRIKAANSE OPSOMMING: RoboCup bevorder navorsing in robotika en multi-robot-stelsels (MRS). Die RoboCup Klein Liga (KL) bied in die besonder die geleentheid om op intreevlak navorsing te doen in hierdie veld. Hierdie tesis verteenwoordig die eerste fase van navorsing in robotika en MRS by Stellenbosch Universiteit. Dit sluit die volledige dokumentasie van die meganiese, elektroniese en sagteware-ontwerp van ’n omnidireksionele sokker-robot vir die KL in. Die robot is ook veronderstel om te dien as ’n hardeware- en sagteware-ontwikkelingsplatform vir navorsing in MRS. Die platform is dus ontwerp met ’n verskeidenheid van uitbreingsmoontlikhede en modulariteit in gedagte asook die moontlikheid om gebruik te maak van ’n hoë-vlak programmeertaal. Om hierdie doelwitte te bereik, maak die robot gebruik van ’n enkel-bord-rekenaar met ’n Linux bedryfstelsel. Verder was ’n sagteware drywer in C++ geskryf om te dien as ’n sagteware-koppelvlak vir toekomstige ontwikkeling op die robot platform. Die robot is ook ontwikkel met die besondere fokus op ’n gedesentraliseerde beheerstels. Player was geïmplementeer as die middelware, wat gebruik kan word vir kommunikasie tussen verskeie robotte in ’n gedesentralliseerde beheerstelsel. Daar is drie toetse uitgevoer om die funksionaliteit van die prototipe te demonstreer, ’n PI spoed beheer toets, ’n rigting akkuraatheidstoets en ’n statiese kommunikasie toets deur van die middelware gebruik te maak. Aanbevelings vir moontlike toekomstige werk word ook verskaf.
Advisors/Committee Members: Scheffer, C., Kim, Y., Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering..
Subjects/Keywords: Mechatronic engineering; Robotics; Multi-robot systems
Smit, A. (2011). Development of a robot for RoboCup Small Size League, utilizing a distributed control architecture for a multi-robot system development platform . (Masters Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/17785
Smit, Albert. “Development of a robot for RoboCup Small Size League, utilizing a distributed control architecture for a multi-robot system development platform.” 2011. Masters Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/17785.
Smit, Albert. “Development of a robot for RoboCup Small Size League, utilizing a distributed control architecture for a multi-robot system development platform.” 2011. Web. 20 Feb 2019.
Smit A. Development of a robot for RoboCup Small Size League, utilizing a distributed control architecture for a multi-robot system development platform. [Internet] [Masters thesis]. Stellenbosch University; 2011. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/17785.
Smit A. Development of a robot for RoboCup Small Size League, utilizing a distributed control architecture for a multi-robot system development platform. [Masters Thesis]. Stellenbosch University; 2011. Available from: http://hdl.handle.net/10019.1/17785
7. Van den Heever, David Jacobus. Development of patient-specific knee joint prostheses for unicompartmental knee replacement (UKR).
Degree: PhD, Mechanical and Mechatronic Engineering, 2011, Stellenbosch University
ENGLISH ABSTRACT: The knee is the largest, most complicated and incongruent joint in the human body. It sustains very high forces and is susceptible to… (more)
ENGLISH ABSTRACT: The knee is the largest, most complicated and incongruent joint in the human body. It sustains very high forces and is susceptible to injury and disease. Osteoarthritis is a common disease prevalent among the elderly and causes softening or degradation of the cartilage and subcondral bone in the joint, which leads to a loss of function and pain. This problem can be alleviated through a surgical intervention commonly termed a “knee replacement”. The aim of a knee replacement procedure is to relieve pain and restore normal function. Ideally, the knee replacement prosthesis should have an articulating geometry similar to that of the patient’s healthy knee, and must allow for normal motion. Unfortunately, this is often problematic since knee prostheses are supplied in standard sizes from a variety of manufacturers and each one has a slightly different design. Furthermore, commercial prostheses are not always able to restore the complex geometry of an individual patient’s original articulating surfaces. This dissertation shows that there is a significant variation between knee geometries, regardless of gender and race. This research aims to resolve the problem in two parts: Firstly by presenting a method for preoperatively selecting the optimal knee prosthesis type and size for a specific patient, and secondly by presenting a design procedure for designing and manufacturing patient-specific unicompartmental knee replacements. The design procedure uses mathematical modelling and an artificial neural network to estimate the original and healthy articulating surfaces of a patient’s knee. The models are combined with medical images from the patient to create a knee prosthesis that is patient-specific. These patient-specific implants are then compared to conventional implants with respect to contact stresses and kinematics. The dissertation concludes that patient-specific implants can have characteristics that are comparable to or better than conventional prostheses. The unique design methodology presented in this dissertation introduces a significant advancement in knee replacement technology, with the potential to dramatically improve clinical outcomes of knee replacement surgery.
AFRIKAANSE OPSOMMING: Die knie is die grootste, mees komplekse en mees ongelyksoortige gewrig in die liggaam. Osteoarthritis is ’n siekte wat algemeen by bejaardes voorkom en die versagting of agteruitgang van die kraakbeen en subchondrale bene in die gewrig tot gevolg het, wat tot ’n verlies van funksionering en pyn lei. Hierdie probleem kan verlig word deur ’n chirurgiese ingryping wat algemeen as ’n “knievervanging” bekend staan. Die doel van ’n knievervangingsprosedure is om pyn te verlig en normale funksionering te herstel. Ideaal gesproke behoort die knievervangingsprostese ’n gewrigsgeometrie te hê wat soortgelyk aan die pasiënt se gesonde knie is, en normale beweging moontlik maak. Ongelukkig is dit dikwels problematies aangesien knieprosteses in standaardgroottes en deur ’n …
Subjects/Keywords: Mechatronic engineering; Atificial knee; Artificial joints
Van den Heever, D. J. (2011). Development of patient-specific knee joint prostheses for unicompartmental knee replacement (UKR) . (Doctoral Dissertation). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/17942
Van den Heever, David Jacobus. “Development of patient-specific knee joint prostheses for unicompartmental knee replacement (UKR).” 2011. Doctoral Dissertation, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/17942.
Van den Heever, David Jacobus. “Development of patient-specific knee joint prostheses for unicompartmental knee replacement (UKR).” 2011. Web. 20 Feb 2019.
Van den Heever DJ. Development of patient-specific knee joint prostheses for unicompartmental knee replacement (UKR). [Internet] [Doctoral dissertation]. Stellenbosch University; 2011. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/17942.
Van den Heever DJ. Development of patient-specific knee joint prostheses for unicompartmental knee replacement (UKR). [Doctoral Dissertation]. Stellenbosch University; 2011. Available from: http://hdl.handle.net/10019.1/17942
8. Swart, Wayne. Nystagmus and eye reflex sensor.
ENGLISH ABSTRACT: Nystagmus is an eye movement pattern that consists of a drifting gaze component, known as the slow phase, followed by a corrective quick… (more)
ENGLISH ABSTRACT: Nystagmus is an eye movement pattern that consists of a drifting gaze component, known as the slow phase, followed by a corrective quick phase component. The presence of nystagmus or the lack thereof under certain conditions can be used for various diagnostic purposes including the diagnosis of physiological, pathological and neurological conditions. The angular velocity of the quick phase can make the detection of nystagmus a challenging task for the untrained eye, since the quick phases are usually comparable with saccadic eye motions. The goal is thus to develop a fully automated diagnostic tool that can identify the presents of nystagmus in a patient’s eye motions. In this thesis, an appropriate eye tracking method was selected from a number of eye tracking methods that are commonly implemented in the literature. A video-oculography goggle concept was chosen based on criteria such as invasiveness, sampling rate, accuracy and telemedicine capability, amongst other nystagmus related necessities. A binocular video-oculography concept was chosen that satisfied the technical requirements and provided a cost-effective design. An automated analysis algorithm was developed for automatic nystagmus identification from eye motion data. The algorithm was validated by testing the performance of the algorithm on an optokinetic nystagmus signal. It proved to provide a reliable automatic identification of nystagmus beats, even in signals that contained nystagmus as well as random motion components. A statistical analysis showed that the algorithm provided a sensitivity of 91.8% and a specificity of 96.5% for pure nystagmus signals, and a sensitivity and specificity of 87.8% and 91.1% respectively for mixed signals.
AFRIKAANSE OPSOMMING: Nystagmus is ’n oogbewegingspatroon wat bestaan uit ’n dwalende tuurkomponent, wat die stadige fase genoem word, gevolg deur ’n vinnige korrigereringsbeweging wat bekend staan as die vinnige fase. Die teenwoordigheid van nystagmus, of afwesigheid daarvan in sekere gevalle, kan gebruik word in ’n verskeidenheid diagnostiese toepassings, onder andere die diagnose van fisiologiese-, patalogiese- en neurologiese kwale. Die hoeksnelheid van die vinnige fase lei daartoe dat nystagmus dikwels moeilik is om te bespeur vir ongeöefende oë, aangesien dit vergelykbaar is met saccade bewegings. Die doel van hierdie navorsing is dus die ontwikkeling van ’n stelsel wat ’n volledige automatiese identifisering van nystagmus kan behartig. ’n Gepaste oogvolgtegniek was gekies vanuit ’n aantal verskillende oogvolgmetodes wat dikwels in die praktyk gebruik word. Die finale keuse was ’n skermbril, video-oogvolgmetode wat gekies was op grond van kriteria soos onder andere, invallendheid, meetfrekwensie, akkuraatheid en geskiktheid vir telemedisyne toepassings. Die ontwikkelde brilkonsep bied ’n koste-effektiewe oplossing, met die moontlikheid om albei oë te volg en bevredig al die bogenoemde tegniese spesifikasies. ’n Geoutomatiseerde nystagmus…
Subjects/Keywords: Mechatronic engineering; Eye motion – Measurement
Swart, W. (2011). Nystagmus and eye reflex sensor . (Masters Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/18019
Swart, Wayne. “Nystagmus and eye reflex sensor.” 2011. Masters Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/18019.
Swart, Wayne. “Nystagmus and eye reflex sensor.” 2011. Web. 20 Feb 2019.
Swart W. Nystagmus and eye reflex sensor. [Internet] [Masters thesis]. Stellenbosch University; 2011. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/18019.
Swart W. Nystagmus and eye reflex sensor. [Masters Thesis]. Stellenbosch University; 2011. Available from: http://hdl.handle.net/10019.1/18019
9. Botha, J. S. F. Autonomous auscultation of the human heart.
ENGLISH ABSTRACT: The research presented in this thesis serves to provide a tool to autonomously… (more)
ENGLISH ABSTRACT: The research presented in this thesis serves to provide a tool to autonomously screen for cardiovascular disease in the rural areas of Africa. Vital information thus obtained from patients can be communicated to advanced medical centres by Telemedicine. Cardiovascular disease is then detected in its initial stages, which is essential to its effective treatment. The system developed in this study uses recorded heart sounds and electrocardiogram signals to distinguish between normal and abnormal heart conditions. This system improves on standard diagnostic tools in that it does not require cumbersome and expensive imaging equipment or a highly trained operator. Heart sound- and electrocardiogram signals from 62 volunteers were recorded with the prototype Precordialcardiogram device as part of a clinical study to aid in the development of the autonomous auscultation software and to screen patients for cardiovascular disease. These volunteers consisted of 28 patients of Tygerberg Hospital with cardiovascular disease and, for control purposes, 34 persons with normal heart conditions. The autonomous auscultation system developed during this study, interprets data obtained with the Precordialcardiogram device to autonomously acquire a normal or abnormal diagnosis. The system employs wavelet soft thresholding to denoise the recorded signals, followed by the segmentation of heart sound by identifying peaks in the electrocardiogram. Novel frequency spectral information was extracted as features from the heart sounds, by means of ensemble empirical mode decomposition and auto regressive modelling. These features proved to be particularly significant and played a major role in the screening capability of the system. New time domain based features were identified, established on the specific characteristics of the various cardiovascular diseases encountered during the study. These features were extracted via the energy ratios between different parts of ventricular systole and diastole of each recorded cardiac cycle. The respective features were classified to characterise typical heart diseases as well as healthy hearts with an ensemble artificial neural network. Herein the decisions of all the members were combined to obtain a final diagnosis. The performance of the autonomous auscultation system used in concert with the Precordialcardiogram device prototype, as determined through the leave-one-out crossvalidation method, had a sensitivity rating of 82% and a specificity rating of 88%. These results demonstrate the potential benefit of the Precordialcardiogram device and the developed autonomous auscultation software in a Telemedicine environment.
AFRIKAANSE OPSOMMING: Hierdie tesis beskryf die navorsing van 'n outonome toetsing en sifting stelsel vir kardiovaskulêre siektes in landelike dele van Afrika, vanwaar mediese inligting per telefoon versend kan word. Die apparaat maak…
Subjects/Keywords: Mechatronic engineering; Auscultation; Cardiovascular system – Diseases – Diagnosis
Botha, J. S. F. (2010). Autonomous auscultation of the human heart . (Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/4239
Botha, J S F. “Autonomous auscultation of the human heart.” 2010. Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/4239.
Botha, J S F. “Autonomous auscultation of the human heart.” 2010. Web. 20 Feb 2019.
Botha JSF. Autonomous auscultation of the human heart. [Internet] [Thesis]. Stellenbosch University; 2010. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/4239.
Botha JSF. Autonomous auscultation of the human heart. [Thesis]. Stellenbosch University; 2010. Available from: http://hdl.handle.net/10019.1/4239
10. Muller, Jacobus Hendrik. Modelling subject-specific patellofemoral joint dynamics.
Thesis (PhD (Mechanical and Mechatronic Engineering)) – University of Stellenbosch, 2010.
ENGLISH ABSTRACT: A methodology to facilitate analysis of dynamic subject-specific patellofemoral function is presented. An… (more)
ENGLISH ABSTRACT: A methodology to facilitate analysis of dynamic subject-specific patellofemoral function is presented. An enhanced understanding of patellofemoral biomechanics will enable orthopaedic surgeons to identify the mechanisms responsible for imbalances in the joint stabilisers, while also providing objective information on which to base treatment methods. Dynamic patellofemoral function of three volunteers was simulated with a musculoskeletal computational model. The individuals underwent scans from which three-dimensional models of their patellofemoral joints were constructed. Skeletal muscles and soft tissue stabilisers were added to the skeletal models, after which subject-specific motion was simulated. After trochlear engagement, the patellae of the volunteers followed a lateral path, whereas patella tilt was subject-specific. Comparison of the predicted tilt and mediolateral position values at 30 degrees knee flexion to in-vivo MRI values showed a mean accuracy of 62.1 % and 96.9 % respectively. The patellofemoral contact load . quadriceps tendon load ratio varied between 0.7 and 1.3, whereas the mediolateral load component . resultant load ratio ranged between 0 and 0.4. Both parameters. values were similar to previous findings. The medial patellofemoral ligament tension decreased with knee flexion, while the patellar tendon-quadriceps tendon ratio followed a similar trend to that of previous findings (varied between 0.4 and 1.2). After induction of a tubercle osteotomy in the coronal plane, Volunteer One.s patella engaged the trochlear groove at an earlier knee flexion angle, while the patella of Volunteer Two only underwent a small medial displacement. Finite element analyses were employed to investigate the influence of the osteotomy on the patellofemoral pressure distribution. The mean pressure in Volunteer One.s patellofemoral joint was alleviated (17 % smaller) at all angles of flexion with the exception of 60 degrees (12 % greater). Pressure in Volunteer Two.s joint was alleviated at 30 and 45 degrees knee flexion (6 % smaller), while it was elevated (9.1 % greater) at other angles of flexion. Two commercial patellofemoral prostheses were tested on the three Volunteers. joints in the virtual environment. Prosthesis Two delivered patella shift and tilt patterns similar to the baseline values. Patellar tendon tension was slightly greater after resurfacing, with the tensions elevated most with Prosthesis Two. Medial patellofemoral ligament tension was reduced most with Prosthesis Two, while lateral retinaculum tension was increased slightly. Prosthesis Two was the best candidate to reproduce patella kinematics, while the patellofemoral kinetics was largely independent from the type of prosthesis used. The prostheses performed worse for Volunteer Three, supporting the need for the development of patient-specific prostheses. Three validated subject-specific musculoskeletal models facilitated the…
Advisors/Committee Members: Scheffer, C., Elvin, A., University of Stellenbosch. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering..
Subjects/Keywords: Mechanical engineering; Biomechanics; Patellofemoral prostheses
Muller, J. H. (2010). Modelling subject-specific patellofemoral joint dynamics . (Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/5306
Muller, Jacobus Hendrik. “Modelling subject-specific patellofemoral joint dynamics.” 2010. Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/5306.
Muller, Jacobus Hendrik. “Modelling subject-specific patellofemoral joint dynamics.” 2010. Web. 20 Feb 2019.
Muller JH. Modelling subject-specific patellofemoral joint dynamics. [Internet] [Thesis]. Stellenbosch University; 2010. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/5306.
Muller JH. Modelling subject-specific patellofemoral joint dynamics. [Thesis]. Stellenbosch University; 2010. Available from: http://hdl.handle.net/10019.1/5306
11. Worst, Siebert Christo. Development of a low cost secondary slave manipulator for a minimally invasive robotic surgical system.
ENGLISH ABSTRACT: Minimally Invasive Surgery (MIS) in human beings is performed by making small incisions in the abdominal region of the patient and inflating the… (more)
ENGLISH ABSTRACT: Minimally Invasive Surgery (MIS) in human beings is performed by making small incisions in the abdominal region of the patient and inflating the abdominal cavity with CO2. This procedure enables the surgeon to manipulate long rigid surgical instruments inside the patient in order to perform the surgery. Unfortunately the current methods of insertion and assembly of MIS instruments limit the surgeon to only five (of a possible seven) Degrees of Freedom (DOF). Along with this, the surgeon’s movements are mirrored (called the Fulcrum effect) and scaled around the point of incision. Minimally invasive surgical robots attempt to alleviate these drawbacks by eliminating the Fulcrum effect, as well as improving dexterity and accuracy. These robots’ abilities to improve the surgeon’s hand-eye coordination, enables the surgeon to perform surgeries using their natural movements with reduced fatigue. As a result of this, the risk to both patient and surgeon is reduced. Existing MIS robotic systems are extremely expensive and large, and as a result they are not widely used. In this thesis a new, lower cost, seven DOF robotic manipulator is further developed. The thesis focuses on the external three DOF Secondary Slave Manipulator (SSM) and combines it with the Primary Slave Manipulator (PSM) that was developed by a previous Masters student. Tests done on the SSM showed that the manipulator has a minimum resolution of 0.7 ± 0.2 mm (mean ± standard deviation) on the shoulder joint’s yaw rotation and 0.5 ± 0.2 mm in pitch rotation. The linear actuator used for insertion has a minimum resolution of 0.2 ± 0.2 mm. A strength test was also conducted and showed that the manipulator is easily capable of producing a 10 N actuation force as required during Minimally Invasive Robotic Surgery (MIRS) procedures. In conclusion the complete system has potential as a viable alternative to the existing systems due to its accuracy and lower cost. Future work will include the development of a user interface and control system for the complete robot.
AFRIKAANSE OPSOMMING: Minimaal Indringende Chirurgie (MIC) op mense word uitgevoer deur klein insnydings in die pasiënt se buik te maak en dan die abdominale holte met CO2 te vul. Dit stel die chirurg in staat om lang, onbuigbare instrumente binne die pasiënt te manipuleer om sodoende die operasie uit te voer. Die manier waarop die MIC instrument ontwerp is en die pasiënt binnegaan, laat egter slegs vyf vryheidsgrade toe, terwyl die chirurg self sewe vryheidsgrade in sy handbewegings het. Verder veroorsaak hierdie instrumente ook dat die chirurg se aksies in spieëlbeeld vertolk word (Fulcrum effek) en geskaleer is. Chirurgiese robotika poog om hierdie nadele teen te werk deur die Fulcrum effek te verwyder, en ook om handvaardigheid en akkuraatheid te bevorder. Die robot se potensiaal om die chirurg se hand-oog koӧrdinasie te verbeter, maak dit moontlik vir die chirurg om op ’n meer natuurlike en gemaklike manier te werk te gaan en bring minder vermoeienis mee. Dit verminder die…
Subjects/Keywords: Mechatronic engineering; Surgical robots – Movements
Worst, S. C. (2012). Development of a low cost secondary slave manipulator for a minimally invasive robotic surgical system . (Masters Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/71618
Worst, Siebert Christo. “Development of a low cost secondary slave manipulator for a minimally invasive robotic surgical system.” 2012. Masters Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/71618.
Worst, Siebert Christo. “Development of a low cost secondary slave manipulator for a minimally invasive robotic surgical system.” 2012. Web. 20 Feb 2019.
Worst SC. Development of a low cost secondary slave manipulator for a minimally invasive robotic surgical system. [Internet] [Masters thesis]. Stellenbosch University; 2012. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/71618.
Worst SC. Development of a low cost secondary slave manipulator for a minimally invasive robotic surgical system. [Masters Thesis]. Stellenbosch University; 2012. Available from: http://hdl.handle.net/10019.1/71618
12. Garth-Davis, Bryan. A needle positioning system for percutaneous procedures.
ENGLISH ABSTRACT: In percutaneous procedures, where the surgeon inserts a needle into a target in the patient, it is challenging to access the target at… (more)
ENGLISH ABSTRACT: In percutaneous procedures, where the surgeon inserts a needle into a target in the patient, it is challenging to access the target at the rst attempt. Repeated needle insertion attempts are highly undesirable, as they lead to increased theatre time, patient haemorrhage and radiation exposure. The proposal of this thesis was to develop a low-cost system to aid surgeons with the process of positioning and orientating the needle prior to insertion. The proposed system uses a stereo pair of images produced by a standard C-arm uoroscope. By applying computer vision techniques, such as triangulation, the desired needle position and orientation are determined from the set of images. An articulated manipulator is used to position and orientate the needle. The surgeon makes selections on the images, via a graphical user interface (GUI), to indicate the desired position and orientation of the needle. Following these selections, an algorithm determines the necessary angles for the manipulator. The surgeon then positions the manipulator accordingly. Results from tests on a phantom showed the system to be repeatable and accurate to 2 mm. This is less accurate than similar, existing systems which, reported accuracies of 0:25 and 1:21 mm. However, 2 mm accuracy is considered adequate as it allows a range of percutaneous procedures to be performed such as needle biopsy, regional anaesthesia, brachytherapy and percutaneous nephrolithotomy (PCNL). Tests on both a phantom kidney and a porcine kidney indicated that the system can function in a real percutaneous procedure and with an anatomical target. The total cost to develop the prototype system was R15 000. The accuracy of the proposed system and the time to gain access to the target indicate that the system can be a bene cial aid to surgeons when performing percutaneous procedures. As minimal X-ray imaging is required, patients will also be spared excessive radiation exposure and theatre time.
AFRIKAANSE OPSOMMING: In perkutane prosedures, waar die chirurg 'n naald in 'n teiken op die pasiënt invoeg, is dit moeilik om met die eerste probeerslag toegang tot die teiken te bekom. Herhaalde pogings om die naald in te voeg is hoogs ongewens, aangesien dit tot verlengde teatertyd, bloeding by pasinte sowel as stralingsblootstelling lei. 'n Laekostestelsel is ontwikkel om chirurge by te staan met die proses om die naald voor invoeging te plaas en te oriënteer. Die stelsel gebruik 'n paar stereobeelde wat deur 'n standaard-C-arm- uoroskoop voortgebring word. Met behulp van rekenaarsigtegnieke, soos triangulasie, word die gewenste naaldposisie en -oriëntasie uit die stel beelde bepaal. 'n Geartikuleerde manipuleerder word gebruik om die naald te plaas en te oriënteer. Die chirurg voer die vereiste invoerdata deur middel van 'n gra ese gebruikerskoppelvlak (GGK) in, waarna 'n algoritme die vereiste hoeke vir die manipuleerder bepaal. Die chirurg plaas dan die manipuleerder dienooreenkomstig. Die resultate van toetse op 'n fantoom…
Subjects/Keywords: Mechatronic engineering; Surgery – Computer vision techniques
Garth-Davis, B. (2012). A needle positioning system for percutaneous procedures . (Masters Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/71626
Garth-Davis, Bryan. “A needle positioning system for percutaneous procedures.” 2012. Masters Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/71626.
Garth-Davis, Bryan. “A needle positioning system for percutaneous procedures.” 2012. Web. 20 Feb 2019.
Garth-Davis B. A needle positioning system for percutaneous procedures. [Internet] [Masters thesis]. Stellenbosch University; 2012. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/71626.
Garth-Davis B. A needle positioning system for percutaneous procedures. [Masters Thesis]. Stellenbosch University; 2012. Available from: http://hdl.handle.net/10019.1/71626
13. Kemp, Iain Henry. Development,testing and fluid interaction simulation of a bioprosthetic valve for transcatheter aortic valve implantation.
ENGLISH ABSTRACT: Bioprosthetic heart valves (BHVs) for transcatheter aortic valve implantation (TAVI) have been rapidly developing over the last decade since the first valve replacement… (more)
ENGLISH ABSTRACT: Bioprosthetic heart valves (BHVs) for transcatheter aortic valve implantation (TAVI) have been rapidly developing over the last decade since the first valve replacement using the TAVI technique. TAVI is a minimally invasive valve replacement procedure offering lifesaving treatment to patients who are denied open heart surgery. The biomedical engineering research group at Stellenbosch University designed a 19 mm balloon expandable BHV for TAVI in 2007/8 for testing in animal trials. In the current study the valve was enlarged to 23 mm and 26 mm diameters. A finite element analysis was performed to aid in the design of the stents. New stencils were designed and manufactured for the leaflets using Thubrikar‟s equations as a guide. The 23 mm valve was manufactured and successfully implanted into two sheep. Fluid structure interaction (FSI) simulations constitute a large portion of this thesis and are being recognized as an important tool in the design of BHVs. Furthermore, they provide insight into the interaction of the blood with the valve, the leaflet dynamics and valve hemodynamic performance. The complex material properties, pulsating flow, large deformations and coupling of the fluid and the physical structure make this one of the most complicated and difficult research areas within the body. The FSI simulations, of the current valve design, were performed using a commercial programme called MSC.Dytran. A validation study was performed using data collected from a cardiac pulse duplicator. The FSI model was validated using leaflet dynamics visualisation and transvalvular pressure gradient comparison. Further comparison studies were performed to determine the material model to be used and the effect of leaflet free edge length and valve diameter on valve performance. The results from the validation study correlated well, considering the limitations that were experienced. However, further research is required to achieve a thorough validation. The comparative studies indicated that the linear isotropic material model was the most stable material model which could be used to simulate the leaflet behaviour. The free edge length of the leaflet affects the leaflet dynamics but does not greatly hinder its performance. The hemodynamic performance of the valve improves with an increase in diameter and the leaflet dynamics perform well considering the increased surface area and length. Many limitations in the software prevented more accurate material models and flow initiation to be implemented. These limitations significantly restricted the research and confidence in the results. Further investigation regarding the implementation of FSI simulations of a heart valve using the commercial software is recommended.
AFRIKAANSE OPSOMMING: Bio-prostetiese hartkleppe (Bioprosthetic Heart Valves - BHVs) wat gebruik word vir transkateter aortaklep-inplantings (Transcatheter Aortic Valve Implantation - TAVI) het geweldig vinnige ontwikkeling getoon in die afgelope tien jaar sedert die eerste klepvervanging wat…
Advisors/Committee Members: Scheffer, C., Blaine, D. C., Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering..
Subjects/Keywords: Mechanical engineering; Bioprosthetic heart valves; Valve hemodynamic performance.
Kemp, I. H. (2012). Development,testing and fluid interaction simulation of a bioprosthetic valve for transcatheter aortic valve implantation . (Masters Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/71710
Kemp, Iain Henry. “Development,testing and fluid interaction simulation of a bioprosthetic valve for transcatheter aortic valve implantation.” 2012. Masters Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/71710.
Kemp, Iain Henry. “Development,testing and fluid interaction simulation of a bioprosthetic valve for transcatheter aortic valve implantation.” 2012. Web. 20 Feb 2019.
Kemp IH. Development,testing and fluid interaction simulation of a bioprosthetic valve for transcatheter aortic valve implantation. [Internet] [Masters thesis]. Stellenbosch University; 2012. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/71710.
Kemp IH. Development,testing and fluid interaction simulation of a bioprosthetic valve for transcatheter aortic valve implantation. [Masters Thesis]. Stellenbosch University; 2012. Available from: http://hdl.handle.net/10019.1/71710
14. Heunis, Jacobus Stephanus. A user interface for a seven degree of freedom surgical robot.
ENGLISH ABSTRACT: This thesis describes the process of developing a user interface for a seven degree of freedom (DOF), minimally invasive surgical robot. For the… (more)
ENGLISH ABSTRACT: This thesis describes the process of developing a user interface for a seven degree of freedom (DOF), minimally invasive surgical robot. For the first two main stages of the overall project, completed by previous students, a primary slave manipulator (PSM) and a secondary slave manipulator (SSM) were developed. The stage in this thesis concentrates on creating a joystick that can control the combined movement of the PSM and SSM. Background information on the field of robotic surgery, with specific reference to current systems’ user interfaces, is given and the technical aspects of the PSM and SSM are determined. This is followed by the motivation and main objectives of the thesis. Objectives were divided into the main categories of mechanical design, electronic design, control system design and testing. The mechanical design of the joystick progresses through a concept development stage, before a final seven DOF articulated arm design is presented and evaluated based on engineering specifications. Aluminium is used as the construction material; electromagnetic brakes are specified for each joint, leading to the final assembly, which is a constructed joystick fulfilling all requirements. The electronic design implements magnetic rotary encoders for the joystick’s position and orientation tracking as well as designs of the necessary power and control circuitry to enable correct joystick functioning. The interfacing of the PSM and SSM had to enable successful communication capabilities between the master and the slave. Several necessary adjustments were therefore made to the slave system, after which the joystick and robot were electronically interfaced to provide a direct serial communication line. For control system design, the joystick and robot were modelled according to the Denavit-Hartenberg principle, which allows direct relation between the position and orientation of the respective end effectors on the joystick and robot sides. Forward kinematic equations were then applied to the joystick; the desired position and orientation of the robot end effector were determined, and inverse kinematic equations were applied to these data to establish the robot’s joint variables. This stage ended with the development of two operational modes: one where only the SSM motors are controlled in order for the slave to follow the master’s movements, and the other where the PSM’s motors are controlled separately. The simultaneous control of all robot motors could not be demonstrated due to fundamental mechanical flaws in the PSM and SSM designs. Finally, testing was undertaken to demonstrate movement control of the robot by the joystick. The intuitiveness of the product was also tested successfully. The study ends with the presentation of the conclusions, the main conclusions being the successful development and testing of a joystick that controls the movement of a surgical robot, as well as the achievement of all main thesis objectives.
AFRIKAANSE OPSOMMING: Hierdie tesis…
Subjects/Keywords: Mechatronic engineering; Robotic surgery – Control systems
Heunis, J. S. (2012). A user interface for a seven degree of freedom surgical robot . (Masters Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/71833
Heunis, Jacobus Stephanus. “A user interface for a seven degree of freedom surgical robot.” 2012. Masters Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/71833.
Heunis, Jacobus Stephanus. “A user interface for a seven degree of freedom surgical robot.” 2012. Web. 20 Feb 2019.
Heunis JS. A user interface for a seven degree of freedom surgical robot. [Internet] [Masters thesis]. Stellenbosch University; 2012. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/71833.
Heunis JS. A user interface for a seven degree of freedom surgical robot. [Masters Thesis]. Stellenbosch University; 2012. Available from: http://hdl.handle.net/10019.1/71833
15. Cockcroft, Stephen John. An evaluation of inertial motion capture technology for use in the analysis and optimization of road cycling kinematics.
ENGLISH ABSTRACT: Optical motion capture (Mocap) systems measure 3D human kinematics accurately and at high… (more)
ENGLISH ABSTRACT: Optical motion capture (Mocap) systems measure 3D human kinematics accurately and at high sample rates. One of the limitations of these systems is that they can only be used indoors. However, advances in inertial sensing have led to the development of inertial Mocap technology (IMCT). IMCT measures kinematics using inertial measurement units (IMUs) attached to a subject's body without the need for external sensors. It is thus completely portable which opens up new horizons for clinical Mocap. This study evaluates the use of IMCT for improving road cycling kinematics. Ten male sub-elite cyclists were recorded with an IMCT system for one minute while cycling at 2, 3.5 and 5.5 W.kg-1 on a stretch of road and on a stationary trainer. A benchmark test was also done where cycling kinematics was measured simultaneously with the IMCT and a gold-standard Vicon optical system. The first goal was to assess the feasibility of conducting field measurements of cycling kinematics. Magnetic analysis results showed that the IMUs near the pedals and handlebars experienced significant magnetic interference (up to 50% deviation in intensity) from ferrous materials in the road bicycles, causing significant errors in kinematic measurement. Therefore, it was found that the IMCT cannot measure accurate full-body kinematics with the subject on a road bicycle. However, the results of the benchmark test with the Vicon showed that the IMCT can still measure accurate hip (root mean square error (RMSE) < 1°), knee (RMSE < 3.5°) and ankle (RMSE < 3°) flexion using its Kinematic Coupling algorithm. The second goal was to determine whether there is a significant difference between road cycling kinematics captured on the road and in a laboratory. The outdoor flexion results were significantly different to the indoor results, especially for minimum flexion (P < 0.05 for all joints). Changes in rider kinematics between high and low power were also found to have significantly more variability on the road (R2 = 0.36, 0.61, 0.08) than on the trainer (R2 = 0.93, 0.89, 0.56) for the hip, knee and ankle joints respectively. These results bring into question the ecological validity of laboratory cycling. Lastly, applications of IMCT for optimizing cycling performance were to be identified. Several aspects of kinematic analysis and performance optimization using the IMCT were evaluated. It was determined that IMCT is most suited for use as a dynamic bicycle fitting tool for analysis of biomechanical efficiency, bilateral asymmetry and prevention of overuse injuries. Recommendations for future work include the elimination of the magnetic interference and integration of the IMCT data with kinetic measurements to develop an outdoor dynamic fitting protocol.
AFRIKAANSE OPSOMMING: Optiese bewegingswaarnemingstelsels (BWS) meet drie-dimensionele menslike kinematika met hoë akkuraatheid en teen hoë monstertempo's. Een van die nadele van BWS is dat hulle…
Subjects/Keywords: Mechatronic engineering; Biomechanical efficiency
Cockcroft, S. J. (2011). An evaluation of inertial motion capture technology for use in the analysis and optimization of road cycling kinematics . (Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/6760
Cockcroft, Stephen John. “An evaluation of inertial motion capture technology for use in the analysis and optimization of road cycling kinematics.” 2011. Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/6760.
Cockcroft, Stephen John. “An evaluation of inertial motion capture technology for use in the analysis and optimization of road cycling kinematics.” 2011. Web. 20 Feb 2019.
Cockcroft SJ. An evaluation of inertial motion capture technology for use in the analysis and optimization of road cycling kinematics. [Internet] [Thesis]. Stellenbosch University; 2011. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/6760.
Cockcroft SJ. An evaluation of inertial motion capture technology for use in the analysis and optimization of road cycling kinematics. [Thesis]. Stellenbosch University; 2011. Available from: http://hdl.handle.net/10019.1/6760
16. Wucher, Tim. The development of a new orthodontic appliance using non-conventional electromechanical methods.
ENGLISH ABSTRACT: Orthodontics is the eld of dentistry concerned with the treatment of maloc- clusion and anomalies of the dento-facial complex. This thesis is concerned… (more)
ENGLISH ABSTRACT: Orthodontics is the eld of dentistry concerned with the treatment of maloc- clusion and anomalies of the dento-facial complex. This thesis is concerned with studying the underlying biomechanical principles of orthodontic tooth movement. It aims to develop a novel treatment approach and an orthodontic appliance to facilitate said approach by employing advanced technologies. A thorough review of the literature is used to form a comprehensive knowledge base pertaining to the factors a ecting orthodontic tooth movement. It is hypothesised that an electromechanical orthodontic appliance could improve treatment by characterising orthodontic cases based on the relationship be- tween the applied mechanical stimulus and the resulting changes to the af- fected structures, which can then be sensed by the appliance. A prototype is built using electronically controllable linear actuators and a custom built force transducer system for measuring orthodontic forces. Electronic circuits are de- veloped to connect the appliance to a USB port and allow it to be controlled from a graphical user interface (GUI). This further facilitates real-time viewing of important orthodontic parameters. Experiments are carried out to evaluate the appliance functionality with regard to the proposed hypothesis. To con- clude, the relevance of the results to the orthodontic eld is highlighted and recommendations for further development of an electromechanical orthodontic appliance are provided.
AFRIKAANSE OPSOMMING: Ortodonsie is die vakgebied in tandheelkunde gemoeid met die behandeling van wanpassing en abnormaliteit van die tand- en gesig-area. Hierdie tesis bestudeer die onderliggende biomeganiese beginsels van ortodontiese tandbeweging om sodoende 'n nuwe benadering sowel as 'n ortodontiese apparaat te ontwikkel om die genoemde benadering te fasiliteer deur gebruik te maak van gevorderde tegnologie. 'n Deeglike oorsig van die literatuur word gebruik om 'n omvattende kennisbasis op te bou rondom die faktore wat ortodontiese tandbeweging a ekteer. Die hipotese word gestel dat 'n elektromeganiese ortodontiese apparaat behandeling kan verbeter deur ortodontiese gevalle te identi seer/- karakteriseer gebaseer op die verhouding tussen die toegepaste meganiese stimulus en die gevolglike veranderinge aan die gea ekteerde strukture wat deur die apparaat aangevoel word. Elektronies-beheerbare lineêre aandrywers en 'n pasgemaakte krag-oordraerstelsel vir die meet van ortodontiese kragte word gebruik om 'n prototipe te vervaardig. Elektroniese stroombane word ontwikkel om die apparaat te koppel aan 'n USB poort sodat dit beheer kan word d.m.v. 'n gra ese gebruikerskoppelvlak. Eksperimente poog om die apparaat funksioneel te evalueer volgens die voorgestelde hipotese. Ter afsluiting: die toepaslikheid van die verwerfde resultate in die ortodontiese vakgebied word beklemtoon en aanbevelings word gemaak vir toekomstige/verdere ontwikkelings m.b.t. 'n elektromeganiese ortodontiese apparaat.
Subjects/Keywords: Mechatronic engineering; Dissertations – Mechatronic engineering
Wucher, T. (2013). The development of a new orthodontic appliance using non-conventional electromechanical methods . (Masters Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/80041
Wucher, Tim. “The development of a new orthodontic appliance using non-conventional electromechanical methods.” 2013. Masters Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/80041.
Wucher, Tim. “The development of a new orthodontic appliance using non-conventional electromechanical methods.” 2013. Web. 20 Feb 2019.
Wucher T. The development of a new orthodontic appliance using non-conventional electromechanical methods. [Internet] [Masters thesis]. Stellenbosch University; 2013. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/80041.
Wucher T. The development of a new orthodontic appliance using non-conventional electromechanical methods. [Masters Thesis]. Stellenbosch University; 2013. Available from: http://hdl.handle.net/10019.1/80041
17. Schwartz, Paul. Design of an impedance guided intra-arterial catheter.
ENGLISH ABSTRACT: This thesis entails the stages of the development of an arterial catheter capable of being guided by the impedance of human tissue. Such… (more)
ENGLISH ABSTRACT: This thesis entails the stages of the development of an arterial catheter capable of being guided by the impedance of human tissue. Such a device would be desired in cases where it is not possible to locate the artery of a patient using anatomical landmarks. This design thus aims to improve the accuracy of first time placement of arterial catheters. The thesis entails the literature study done in order to initiate the development of said device, followed by preliminary concept design and evaluation. The thesis also contains a description of all experimental phases, done on in vitro tissue samples, in vivo samples in living porcine subjects and in vivo samples in living human patients. Experiments were performed to determine if any repeatable noticeable difference in tissue impedance could be identified and utilized in the hope of guiding this device using acquired differences in tissue impedance. The different stages of development for the prototype used in these tests are also described in detail. In addition, the results of the different tests are presented, which prove that there is a significant difference between blood tissue impedance and the surrounding tissue types encountered, allowing for guidance of the proximal tip of the arterial catheter, based on the tissue impedance measured. Finally, the thesis entails a description of further work which could be performed if this concept were to be considered as a marketable product.
AFRIKAANSE OPSOMMING: Hierdie tesis behels die verskillende stappe in die ontwerp van 'n kateter wat deur middel van die verskillende impedansie vlakke van biologiese weefsel gelei kan word in die menslikke liggaam. Sò ‘n toestel sal behulpsaam wees in gevalle waar plasing nie gedoen kan word met die behulp van anatomiese landmerke nie. Hierdie ontwerp mik dus om die akkuraatheid van die plasing van kateters te verbeter. Die tesis behels die literatuur studies benodig om sò 'n toestel te ontwerp, gevolg deur voorlopige konsep ontwerpe en die evaluasie van hierdie konsepte. Die tesis behels ook die verskillende eksperimentele fases van die projek; eksperimente op in vitro weefsel monsters, in vivo diere toetse en in vivo kliniese toetse op menslike weefsel. Al hierdie eksperimente is gedoen om te bepaal of enige herhaalbare, waarneembare verskil in weefsel impedansie geidentifiseer kan word en dus gebruik word met die hoop om diè teoretiese kateter te lei met behulp van diè verskil in weefsel impedansie. Die verskillende stappe van die ontwerp van die prototipes gebruik in hierdie eksperimente word ook in detail beskryf. Die resultate van die verskillende eksperimente word ook aangebied, wat bewys dat daar 'n beduidende verskil is tussen die impedansie van bloed weefsel en die impedansie van die aanliggende weefsel tipes, wat dus impliseer dat die proksimale punt van die kateter gelei kan word deur die gemete impedansie by die punt van die toestel, gebaseer op die resultate wat gevind is. Laastens behels die tesis ook 'n…
Schwartz, P. (2013). Design of an impedance guided intra-arterial catheter . (Masters Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/80103
Schwartz, Paul. “Design of an impedance guided intra-arterial catheter.” 2013. Masters Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/80103.
Schwartz, Paul. “Design of an impedance guided intra-arterial catheter.” 2013. Web. 20 Feb 2019.
Schwartz P. Design of an impedance guided intra-arterial catheter. [Internet] [Masters thesis]. Stellenbosch University; 2013. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/80103.
Schwartz P. Design of an impedance guided intra-arterial catheter. [Masters Thesis]. Stellenbosch University; 2013. Available from: http://hdl.handle.net/10019.1/80103
18. Cho, Kyung Jin. Quantification of the normal patellofemoral shape and its clinical applications.
ENGLISH ABSTRACT: The shape of the knee’s trochlear groove is a very important factor in the overall stability of the knee. However, a quantitative description… (more)
ENGLISH ABSTRACT: The shape of the knee’s trochlear groove is a very important factor in the overall stability of the knee. However, a quantitative description of the normal three-dimensional geometry of the trochlea is not available in the literature. This is also reflected in the poor outcomes of patellofemoral arthroplasty (PFA). In this study, a standardised method for femoral parameter measurements on three-dimensional femur models was established. Using software tools, virtual femur models were aligned with the mechanical and the posterior condylar planes and this framework was used to measure the femoral parameters in a repeatable way. An artificial neural network (ANN), incorporating the femoral parameter measurements and classifications done by experienced surgeons, was used to classify knees into normal and abnormal categories. As a result, 15 knees in the database were classified by the ANN as being normal. Furthermore, the geometry of the normal knees was analysed by fitting B-spline curves and circular arcs on their sagittal surface curves to prove and reconfirm that the groove has a circular shape on a sagittal plane. Self-organising maps (SOM), which is a type of ANN, was trained with the acquired data of the normal knees and in this way the normal trochlear geometry could be predicted. The prediction of the anterior-posterior (AP) distance and the trochlear heights showed an average agreement of 97 % between the actual and the predicted normal geometries. A case study was conducted on four types of trochlear dysplasia to determine a normal geometry for these knees, and a virtual surface reconstruction was performed on them. The study showed that the trochlea was deepened after the surface reconstruction, having an average trochlea depth of 5.5 mm compared to the original average value of 2.9 mm. In summary, this research proposed a quantitative method for describing and predicting the normal geometry of a knee by making use of ANN and the femoral parameters that are unaffected by trochlear dysplasia.
AFRIKAANSE OPSOMMING: Die vorm van die trogleêre keep is ’n belangrike faktor in patella-stabiliteit. Tog is ’n kwantitatiewe beskrywing van die normale driedimensionele geometrie van die troglea nog nie beskikbaar nie, wat duidelik blyk uit die swak uitkomste van patellofemorale artroplastie (PFA). In hierdie studie is ’n gestandaardiseerde metode vir die meting van femorale parameters op grond van driedimensionele femurmodelle ontwikkel. Die femurmodel is in lyn gebring met die meganiese en posterior kondilêre vlak, welke raamwerk gebruik is om die femorale parameters op ’n herhaalbare wyse te meet. Die normale knieë is geklassifiseer met ’n kunsmatige neurale netwerk (ANN), wat die femorale parameter-mate sowel as die chirurgiese klassifikasie ingesluit het, en 15 knieë is gevolglik as normaal aangewys. Die normaleknie-geometrie is ontleed deur B-latkrommes en sirkelboë op die sagittale oppervlak-kurwes aan te bring om te bewys en te herbevestig dat die keep uit ’n sirkelvorm op ’n sagittale vlak…
Advisors/Committee Members: Muller, J. H., Scheffer, C., Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering..
Subjects/Keywords: Mechanical engineering; Dissertations – Mechanical engineering
Cho, K. J. (2013). Quantification of the normal patellofemoral shape and its clinical applications . (Masters Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/80285
Cho, Kyung Jin. “Quantification of the normal patellofemoral shape and its clinical applications.” 2013. Masters Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/80285.
Cho, Kyung Jin. “Quantification of the normal patellofemoral shape and its clinical applications.” 2013. Web. 20 Feb 2019.
Cho KJ. Quantification of the normal patellofemoral shape and its clinical applications. [Internet] [Masters thesis]. Stellenbosch University; 2013. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/80285.
Cho KJ. Quantification of the normal patellofemoral shape and its clinical applications. [Masters Thesis]. Stellenbosch University; 2013. Available from: http://hdl.handle.net/10019.1/80285
19. Elson, Wesley De Vere. Development of an intravenous oxygenator.
Elson, Wesley De Vere. “Development of an intravenous oxygenator.” 2014. Masters Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/86494.
Elson, Wesley De Vere. “Development of an intravenous oxygenator.” 2014. Web. 20 Feb 2019.
Elson WDV. Development of an intravenous oxygenator. [Internet] [Masters thesis]. Stellenbosch University; 2014. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/86494.
20. Koegelenberg, Suretha. Application of laser doppler vibrocardiography for human heart auscultation.
Koegelenberg, Suretha. “Application of laser doppler vibrocardiography for human heart auscultation.” 2014. Masters Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/86649.
Koegelenberg, Suretha. “Application of laser doppler vibrocardiography for human heart auscultation.” 2014. Web. 20 Feb 2019.
Koegelenberg S. Application of laser doppler vibrocardiography for human heart auscultation. [Internet] [Masters thesis]. Stellenbosch University; 2014. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/86649.
21. Visser, Cobus. A micro approach to quantitative dehydration sensor development.
Visser, Cobus. “A micro approach to quantitative dehydration sensor development.” 2015. Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/97137.
Visser, Cobus. “A micro approach to quantitative dehydration sensor development.” 2015. Web. 20 Feb 2019.
Visser C. A micro approach to quantitative dehydration sensor development. [Internet] [Thesis]. Stellenbosch University; 2015. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/97137.
22. Van der Merwe, Johan. Continued development of a joint-type knee wear simulator.
ENGLISH ABSTRACT: This thesis is concerned with the continued development of the Stellenbosch University joint-type knee wear simulator. Initially, information regarding simulators from the literature… (more)
ENGLISH ABSTRACT: This thesis is concerned with the continued development of the Stellenbosch University joint-type knee wear simulator. Initially, information regarding simulators from the literature and commercial entities was collected to provide a knowledge base for current and future work. To further the design of the simulator itself, electronic hardware and software subsystems was developed and evaluated during experimental testing procedures. National Instruments’ cDAQ 9174 data acquisition unit was deemed inadequate for real-time inputoutput control, though proved sufficient for signal capturing purposes in conjunction with LabView software. Furthermore, the various servo-pneumatic sub-circuits’ individual ability to conform to the ISO 14243 series standards’ protocol led to the estimation of measurable performance criteria and the application to a single circuit for illustration. The anterior/posterior actuation circuit in question demonstrated adequate performance for the cases where the piston’s rod was respectively fixed and free to move. In-silico modelling and identification of the relevant servo-pneumatic components then commenced, with the valve and cylinder chamber models yielding adequate estimates of the recorded data. The identified quasi-static friction model proved sensitive to transient effects present within the system, resulting in performance deterioration of the integrated model. Sufficiently accounting for these effects would result in the emergence of the sub-circuit’s model as an invaluable tool in terms of control system development, prediction of the simulator’s behaviour and subsequent design recommendations. Future work therefore concerns improvement, identification and integration of the various sub-circuit models to fully exploit the aforementioned advantages.
AFRIKAANSE OPSOMMING: Hierdie tesis handel oor die voortgesette ontwikkeling van Universiteit Stellenbosch se gewrigstipe knie-afslytingsimulator. Aanvanklik is inligting versamel vanaf literatuur en kommersiële entiteite om sodoende ’n kennisbasis te verskaf vir huidige en toekomstige werk. Elektroniese hardeware en sagteware stelsels is ontwerp en geëvalueer tydens toetsprosedures om die ontwerp van die simuleerder self te verbeter. National Instruments se cDAQ 9174 dataversamelaarseenheid word onvoldoende geag vir intydse inset-uitset beheer, maar wel vir dataversamelingsdoeleindes tesame met LabView sagteware. Die nodigheid om die verskeie servo-pneumatiese sub-stroombane se individuele vermoë om aan te pas by die ISO 14243-reeks se protokol-standaarde te ondersoek, het gelei tot die beraming van meetbare werkverrigtingskriteria en die toepassing daarvan ter illustrasie. Die anterior/posterior stroombaan het voldoende werksverrigting getoon vir studies waar die suier se stang onderskeidelik vas en los was. In-silico modellering en die identifisering van servo-pneumatiese komponente het hierna begin. Die klep en silinderkamer modelle het voldoende skattings gelewer van die gemete…
Advisors/Committee Members: Scheffer, C., Muller, C., Stellenbosch University. Faculty of Engineering. Dept. of Mechanical & Mechatronic Engineering..
Van der Merwe, J. (2012). Continued development of a joint-type knee wear simulator . (Masters Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/19953
Van der Merwe, Johan. “Continued development of a joint-type knee wear simulator.” 2012. Masters Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/19953.
Van der Merwe, Johan. “Continued development of a joint-type knee wear simulator.” 2012. Web. 20 Feb 2019.
Van der Merwe J. Continued development of a joint-type knee wear simulator. [Internet] [Masters thesis]. Stellenbosch University; 2012. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/19953.
Van der Merwe J. Continued development of a joint-type knee wear simulator. [Masters Thesis]. Stellenbosch University; 2012. Available from: http://hdl.handle.net/10019.1/19953
23. Rauch, Hanz Frederick. The development of a system that emulates percussion to detect the borders of the liver.
Percussion is a centuries old bedside diagnostic technique that is used to diagnose various conditions… (more)
Percussion is a centuries old bedside diagnostic technique that is used to diagnose various conditions of the thorax and abdomen, among these, abnormalities of the liver. The physician taps the patient’s skin in the area of interest to determine the qualities or presence of the underlying tissue or organ, by listening to the generated sound. The research contained in this thesis views percussion as a system identification method which uses an impulse response to identify the underlying system. A design employing an electromagnetic actuator as input pulse generator and accelerometer as impulse response recorder was motivated and built. Tests were performed on volunteers and the recorded signals were analysed to find methods of identifying the presence of the liver from these signals. The analyses matched signals to models or simply extracted signal features and matched these model parameters or signal features to the presence of the liver. Matching was done using statistical pattern recognition methods and the true presence of the liver was established using MR images. Features extracted from test data could not be matched to the presence of the liver with sufficient confidence which led to the conclusion that either the test, apparatus or analysis was flawed. The lack of success compelled a further test on a mock-up of the problem – a silicone model with an anomaly representing the organ under test. Results from these tests showed that signals should be measured further from the actuator and the approach followed during this test could lead to the successful location of the anomaly and discrimination between subtle differences in the consistency thereof. It is concluded that further research should aim to first validate percussion as performed by the physician and increase complexity in a phased manner, validating results and apparatus at each step. The approach followed was perhaps too bold in light of the lack of fundamental understanding of percussion and the underlying mechanisms.
Advisors/Committee Members: Scheffer, C., Van Rooyen, G-J., University of Stellenbosch. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering..
Subjects/Keywords: Mechatronic engineering; Liver – Diseases – Diagnosis; Actuators
Rauch, H. F. (2009). The development of a system that emulates percussion to detect the borders of the liver . (Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/2331
Rauch, Hanz Frederick. “The development of a system that emulates percussion to detect the borders of the liver.” 2009. Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/2331.
Rauch, Hanz Frederick. “The development of a system that emulates percussion to detect the borders of the liver.” 2009. Web. 20 Feb 2019.
Rauch HF. The development of a system that emulates percussion to detect the borders of the liver. [Internet] [Thesis]. Stellenbosch University; 2009. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/2331.
Rauch HF. The development of a system that emulates percussion to detect the borders of the liver. [Thesis]. Stellenbosch University; 2009. Available from: http://hdl.handle.net/10019.1/2331
24. Esterhuyse, Anton. Structural design of a stent for a percutaneous aortic heart valve.
Elderly patients suffering from aortic valvular dysfunction are often denied aortic valve replacement due to… (more)
Elderly patients suffering from aortic valvular dysfunction are often denied aortic valve replacement due to the fact that they are classified as too old and fragile to handle the physical stress of open-heart surgery and cardio-pulmonary bypass. There exists a need for an alternative solution which places less physical stress on the body. The development of a percutaneous aortic heart valve (PAHV), which may be implanted through a minimally invasive procedure, will provide a solution to old and fragile patients who otherwise have a very limited life expectancy. The development of such a device entails a costly and time-consuming process which involves a number of phases, including a prototype development phase, an in-vitro testing phase, an animal trial phase and a human trial phase. This thesis focuses on the design and analysis of the stent component for a PAHV, suitable for implantation in sheep (animal trial phase). The process of developing a first prototype, involved an analysis of the stent design requirements. This analysis was followed by a concept generation phase as well as comprehensive finite element (FE) analyses of the most promising concepts. The objective of the FE analyses was to determine the effects of a variation in strut width on the performance characteristics of the concepts. Based on the results of the FE analyses, final geometries were selected for each of the two most promising concepts. Subsequent to the selection of the final geometries, a number of prototypes were manufactured. The prototypes were subjected to an electro-polishing process. An experimental analysis was also conducted on the prototypes to evaluate the accuracy of the (FE) simulations as well as the actual performance of the stent prototypes. The results of the FE analyses and experimental analyses indicated that strut width had a substantial influence on the parameters that were defined to characterise stent performance. The results of the analyses also highlighted the advantages and disadvantages of each concept and aided in identifying the concept that would be most suitable for the required application. Limitations of the study were identified and recommendations were made to assist the continued research and development of the device.
Advisors/Committee Members: Scheffer, C., Van der Westhuizen, K., University of Stellenbosch. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering..
Subjects/Keywords: Mechanical engineering; Heart – Surgery; Stents (Surgery); Aortic valve; Mechanical and Mechatronic Engineering
Esterhuyse, A. (2009). Structural design of a stent for a percutaneous aortic heart valve . (Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/2706
Esterhuyse, Anton. “Structural design of a stent for a percutaneous aortic heart valve.” 2009. Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/2706.
Esterhuyse, Anton. “Structural design of a stent for a percutaneous aortic heart valve.” 2009. Web. 20 Feb 2019.
Esterhuyse A. Structural design of a stent for a percutaneous aortic heart valve. [Internet] [Thesis]. Stellenbosch University; 2009. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/2706.
Esterhuyse A. Structural design of a stent for a percutaneous aortic heart valve. [Thesis]. Stellenbosch University; 2009. Available from: http://hdl.handle.net/10019.1/2706
25. Becker, Konrad Wilhelm. Research into adventitious lung sound signals originating from pulmonary tuberculosis using electronic auscultation.
Pulmonary tuberculosis is a common and potentially deadly infectious disease, commonly affecting the respiratory area.… (more)
Pulmonary tuberculosis is a common and potentially deadly infectious disease, commonly affecting the respiratory area. Over one-third of the world’s population is infected with the tuberculosis bacterium. Since pulmonary tuberculosis damages the respiratory area, the sound properties of infected lungs differ from those of non-infected lungs. However, auscultation is often ruled out as a reliable diagnostic technique due to the random position and severity of damage to the lungs as well as requiring the personal and trained judgment of an experienced medical practitioner. This project investigates a possible improvement in the pulmonary diagnostic and treatment field by applying electronic and computer-aided sound analysis techniques to analyze respiratory actions beyond human audible judgment. Respiratory sounds of both healthy subjects and subjects who were infected with pulmonary tuberculosis were recorded from seven locations per lung on both the posterior and anterior chest walls, using self-designed hardware. Adaptive filtering signal and analysis techniques yielded a wide range of signal features. This included analysis for time, frequency and both wheeze and crackle adventitious respiratory sounds. Following the analysis, statistical methods identified the most attractive signal measurements capable of separating the recordings of healthy and unhealthy respiratory sounds. Selected signal features were used with neural network optimization to obtain a successful implementation for the semi-automated identification of healthy and unhealthy respiratory sounds originating from pulmonary tuberculosis, with a performance of over 80% for sensitivity, specificity and accuracy. The success of categorizing the recordings justifies the capabilities of the digital analysis of respiratory sounds and supports an argument for further research and refinement into the assessment of pulmonary tuberculosis by electronic auscultation. Further research is recommended, with improvements justified and highlighted in this report.
Advisors/Committee Members: Scheffer, C., Blanckenberg, M. M., University of Stellenbosch. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering..
Subjects/Keywords: Mechatronic engineering; Tuberculosis; Auscultation
Becker, K. W. (2009). Research into adventitious lung sound signals originating from pulmonary tuberculosis using electronic auscultation . (Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/1556
Becker, Konrad Wilhelm. “Research into adventitious lung sound signals originating from pulmonary tuberculosis using electronic auscultation.” 2009. Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/1556.
Becker, Konrad Wilhelm. “Research into adventitious lung sound signals originating from pulmonary tuberculosis using electronic auscultation.” 2009. Web. 20 Feb 2019.
Becker KW. Research into adventitious lung sound signals originating from pulmonary tuberculosis using electronic auscultation. [Internet] [Thesis]. Stellenbosch University; 2009. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/1556.
Becker KW. Research into adventitious lung sound signals originating from pulmonary tuberculosis using electronic auscultation. [Thesis]. Stellenbosch University; 2009. Available from: http://hdl.handle.net/10019.1/1556
26. Smuts, Adriaan Nicolaas. Design of tissue leaflets for a percutaneous aortic valve.
Smuts, Adriaan Nicolaas. “Design of tissue leaflets for a percutaneous aortic valve.” 2009. Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/1625.
Smuts, Adriaan Nicolaas. “Design of tissue leaflets for a percutaneous aortic valve.” 2009. Web. 20 Feb 2019.
Smuts AN. Design of tissue leaflets for a percutaneous aortic valve. [Internet] [Thesis]. Stellenbosch University; 2009. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/1625.
27. De Beer, Neal. Development of a process chain for digital design and manufacture of patient-specific intervertebral disc implants with matching endplate geometries.
De Beer, Neal. “Development of a process chain for digital design and manufacture of patient-specific intervertebral disc implants with matching endplate geometries.” 2011. Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/6564.
De Beer, Neal. “Development of a process chain for digital design and manufacture of patient-specific intervertebral disc implants with matching endplate geometries.” 2011. Web. 20 Feb 2019.
De Beer N. Development of a process chain for digital design and manufacture of patient-specific intervertebral disc implants with matching endplate geometries. [Internet] [Thesis]. Stellenbosch University; 2011. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/6564.
28. Delport, Sven. The optimal patient-specific placement of the reverse total shoulder component.
Degree: MSc, Mechanical and Mechatronic Engineering, 2015, Stellenbosch University
ENGLISH ABSTRACT: Reverse total shoulder arthroplasty is used as the treatment for arthritic rotator cuff deficient shoulders. Some of the most common complications of a… (more)
ENGLISH ABSTRACT: Reverse total shoulder arthroplasty is used as the treatment for arthritic rotator cuff deficient shoulders. Some of the most common complications of a reverse shoulder arthroplasty are scapular notching, glenoid dissociations, glenohumeral dislocation, loosening or dissociation of the humeral component and nerve injury. Clinical outcomes are dependent on the preoperative diagnosis, the function of the deltoid and remaining rotator cuff muscles, biomechanical design of the prosthesis, and the orientation and placement of the reverse shoulder component. This study aims to optimize the patient-specific placement of a reverse shoulder component. A simulation software package was developed that can be used to determine the optimal placement of the reverse shoulder prosthesis for a specific patient. This is achieved by maximizing the humerothoracic range of motion and minimizing the adduction deficit. The motion of the simulation model is driven by shoulder complex motion equations adjusted for each patient. This data was obtained from literature with the motion of the arm fixed to the coronal, scapular and sagittal elevation planes. The influence of the various components of the Tornier Aequalis® - Reversed II system, together with changing the glenoid component inclination and humeral component retroversion, was investigated. This allowed the simulation software to be verified and validated, as well as applying the insight and knowledge gained to a case study. Further simulations evaluated a design change of the humeral component neck-shaft angle from the standard 155 ° to 145 ° or 165 °. The reverse shoulder simulation software provides accurate patient-specific Three Dimensional (3D) pre-operative planning and shoulder complex motion simulation.
AFRIKAANSE OPSOMMING: Omgekeerde volledige skouerartoplastie word as behandeling van ontsteking in gewrigsomhulsel-aangetaste skouers gebruik. Onder die algemeenste komplikasies van 'n omgekeerde skouergewrig-operasie is kepe in die skouerblad (skapulier), lostrekkings of onthegting van die gewrigskom (glenoïede), ontwrigting van die boarm/skouergewrig, die loskom of onthegting van die boarmbeen en beskadiging van senuwees. Mediese resultate is afhanklik van diagnose voor die operasie, die werking van die driehoekspier (deltoïede) en oorblywende draaispiere, die biomeganiese ontwerp van die prostese en die oriëntasie en plasing van die omgekeerde skouerkomponent. Hierdie studie is gemik op die beste pasiënt-spesifieke plasing van die omgekeerde skouerkomponent. Die simulasie-sagtewarepakket wat ontwikkel is, kan gebruik word om die optimale plasing van die omgekeerde skouerprostese in die geval van 'n spesifieke pasiënt te bepaal. Dit word gedoen deur die bewegingsvermoë van die bo-armbeen te maksimaliseer en die gebrekkige werking van die trekspiere te minimaliseer. Die werking van die simulasiemodel word gedryf deur die beweging van skouerkomponente te vergelyk, aangepas vir elke pasiënt. Hierdie data is verkry uit…
Subjects/Keywords: Reverse shoulder component; Arthritic rotator cuff deficient shoulder – Treatment
…Stellenbosch University https://scholar.sun.ac.za Contents Declaration i Abstract ii… …1 1 2 2 3 5 5 5 7 9 14 14 15 15 16 16 Stellenbosch University https… …44 45 45 46 46 46 46 48 48 49 49 49 Stellenbosch University https://scholar.sun.ac.za… …82 91 91 91 Stellenbosch University https://scholar.sun.ac.za List of Figures 2.1 2.2… …32 32 33 34 35 36 38 40 41 Stellenbosch University https://scholar.sun.ac.za LIST OF…
Delport, S. (2015). The optimal patient-specific placement of the reverse total shoulder component . (Masters Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/97141
Delport, Sven. “The optimal patient-specific placement of the reverse total shoulder component.” 2015. Masters Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/97141.
Delport, Sven. “The optimal patient-specific placement of the reverse total shoulder component.” 2015. Web. 20 Feb 2019.
Delport S. The optimal patient-specific placement of the reverse total shoulder component. [Internet] [Masters thesis]. Stellenbosch University; 2015. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/97141.
Delport S. The optimal patient-specific placement of the reverse total shoulder component. [Masters Thesis]. Stellenbosch University; 2015. Available from: http://hdl.handle.net/10019.1/97141
29. Minai Zaiem, Hamed. Evaluation of active acoustic methodology in diagnosis of pleural effusion.
ENGLISH ABSTRACT: Pleural effusion is a common respiratory condition that is characterized by an abnormal collection of fluid in the lung cavity. In this study,… (more)
ENGLISH ABSTRACT: Pleural effusion is a common respiratory condition that is characterized by an abnormal collection of fluid in the lung cavity. In this study, an innovation using the transmission of sound into the respiratory system as a novel tool to detect fluid in the lung was developed. First, the method was evaluated on a phantom model of a lung. Based on the results of this test model, the appropriate technique was used in a clinical study. This method has several advantages, such as that is non-invasive, low cost, and easy for clinical review. Two techniques, including analysis of the frequency response of the model and the transient time of transmitted sound in the lung, were evaluated in the phantom models of the human lung. Two phantom models with similar geometry to the human lung, including a healthy model (without fluid in the model) and a pleural effusion model (with bulk of fluid in the model) were developed. These models have acoustical properties similar to the lung parenchyma. To obtain the frequency responses of the model, a sine sweep signal was transmitted into the model and the frequency response of the model was then calculated using the fast Fourier transform. The transient time of the transmitted sound was calculated using a cross correlation method. The results show that the locations of fluid in the model were detectable using both techniques. However, the transient time technique is better than the frequency response technique because it is simple, fast, and has potential for use in a clinical enviorment. Based on the results obtained from the phantoms, the transient time method was performed on both 22 healthy participants and four patients diagnosed with pleural effusion. To perform this technique on human subjects, a data acquisition system was developed. Two types of sound, including a complex chirp sound and a polyphonic sound, were transmitted into the respiratory systems of the participants. The time delay between a reference microphone, located on the trachea of the subject, and eight microphones attached to the chest was computed using a cross correlation method, and the effect of inhalation and lung size on the transient time of transmitted sound on the healthy subject was evaluated. The results show that using transmission of sound in the lung is a promising technique in the diagnosis of pleural effusion.
AFRIKAANSE OPSOMMING: Pleurale effusie is 'n algemene respiratoriese toestand wat gekenmerk word deur 'n abnormale versameling van vloeistof in die longholte. In hierdie studie is 'n innoverende manier ontwikkel om vloeistof in die long met behulp van die transmissie van klank te bespeur. Die metode is eers op 'n fantoommodel van 'n long geëvalueer. Op grond van die resultate van hierdie toetsmodel is die geskikte tegniek in 'n kliniese studie gebruik. Hierdie metode het verskeie voordele, soos dat dit ingreepsvry is, nie duur is nie en kliniese evaluering moontlik maak. Twee tegnieke, naamlik ontleding van die frekwensierespons van die model en die oorgangstyd van…
…Stellenbosch University http://scholar.sun.ac.za 3. Evaluation of active acoustic… …66 viii Stellenbosch University http://scholar.sun.ac.za 4.6 Results and discussion… …108 ix Stellenbosch University http://scholar.sun.ac.za List of figures Figure 1… …44 x Stellenbosch University http://scholar.sun.ac.za Figure 33. (a)… …Stellenbosch University http://scholar.sun.ac.za Figure 61. Frequency response of the healthy model…
Minai Zaiem, H. (2013). Evaluation of active acoustic methodology in diagnosis of pleural effusion . (Masters Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/80252
Minai Zaiem, Hamed. “Evaluation of active acoustic methodology in diagnosis of pleural effusion.” 2013. Masters Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/80252.
Minai Zaiem, Hamed. “Evaluation of active acoustic methodology in diagnosis of pleural effusion.” 2013. Web. 20 Feb 2019.
Minai Zaiem H. Evaluation of active acoustic methodology in diagnosis of pleural effusion. [Internet] [Masters thesis]. Stellenbosch University; 2013. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/80252.
Minai Zaiem H. Evaluation of active acoustic methodology in diagnosis of pleural effusion. [Masters Thesis]. Stellenbosch University; 2013. Available from: http://hdl.handle.net/10019.1/80252
30. Frew, David Anthony. The design, development and vibration analysis of a high-speed aerostatic bearing.
Thesis presented in partial fulfilment of the requirements for the degree of Master of Engineering… (more)
Thesis presented in partial fulfilment of the requirements for the degree of Master of Engineering Science (Mechanical) at the University of Stellenbosch.
ENGLISH ABSTRACT: This thesis examines the development of a specialized, high-speed bearing in order to reduce vibration levels, reduce cutting times and increase blade stability during diamond sawing. The sawing process is required to be smooth, straight and unhindered – a task which is made difficult by the extreme hardness of the diamond as well as unseen grains which could potentially ruin the cut by deflecting the blade. This has an adverse effect on the quality of the cut and the yield obtained from the stone. The current equipment used for diamond sawing is very basic and a significant improvement can be made in terms of quality and sawing speed with the addition of an improved bearing. An aerostatic bearing was designed in order to achieve lower vibration levels and increased spindle speeds. A speed of 18 500 rpm was achieved with this bearing. A numerical model of the bearing was built with the aim of predicting the bearing’s dynamic behaviour. A finite element method (FEM) analysis was done to confirm the rigid body assumption made. Experimental modal analysis (EMA) was done to determine the frequencies and damping ratios of the natural modes of the rotor. The model was seen to predict the frequencies of the modes to within 6%. This model would be used for future design work to ensure that the frequencies of these modes are designed outside of the operating speed range of the aerostatic bearing. Tests were done to compare the vibration levels between the conventional machine and the aerostatic machine during sawing. The overall RMS acceleration was reduced by 70% on the housing of the aerostatic machine and by 50% on the diamond clamp.
AFRIKAANSE OPSOMMING: Hierdie tesis ondersoek die ontwikkeling van ‘n gespesialeerde, hoë-spoed laer om vibrasie en sny tye te verminder, asook om lem stabilitiet te verhoog in die diamant sny proses. Die sny proses moet glad, reguit en akkuraat wees, maar dit is nie altyd moontlik nie as gevolg van die variasie in hardheid van die diamant asook die naat in die daimant wat die lem maklik kan laat afwyk. Hierdie het ‘n negative effek op die kwalitiet van die snit. Die konvensionele diamant saag masjien is baie eenvoudig en ‘n groot verbetering in die snit kwalitiet en lemspoed is moontlik as ‘n nuwe laer ontwerp en implementeer kan word. ‘n Aerostatiese laer en rotor is ontwikkel om die vibrasie te verminder en die lemspoed to verhoog. ‘n Lemspoed van 18 500 rpm was verkry met die nuwe laer. ‘n Numeriese model is ontiwkkel om die beweging van die rotor dinamies te bereken. Die Eindige Element Metode (EEM) is gebruik om te bepaal of die aanname dat die rotor rigied is, wel aanvaarbaar is. Eksperimentele Modale Analise (EMA) is gebuik om die natuurlike frekwensies en die dempingsverhoudings vir die rotor te bepaal. Die…
Subjects/Keywords: Diamond cutting; Aerostatic bearing; Aerostatic bearing vibration; Bearing vibration; Mechanical and Mechatronic Engineering
Frew, D. A. (2007). The design, development and vibration analysis of a high-speed aerostatic bearing . (Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/4484
Frew, David Anthony. “The design, development and vibration analysis of a high-speed aerostatic bearing.” 2007. Thesis, Stellenbosch University. Accessed February 20, 2019. http://hdl.handle.net/10019.1/4484.
Frew, David Anthony. “The design, development and vibration analysis of a high-speed aerostatic bearing.” 2007. Web. 20 Feb 2019.
Frew DA. The design, development and vibration analysis of a high-speed aerostatic bearing. [Internet] [Thesis]. Stellenbosch University; 2007. [cited 2019 Feb 20]. Available from: http://hdl.handle.net/10019.1/4484.
Frew DA. The design, development and vibration analysis of a high-speed aerostatic bearing. [Thesis]. Stellenbosch University; 2007. Available from: http://hdl.handle.net/10019.1/4484