Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2009. / 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.

Thesis (MScEng (Mechanical and Mechatronic Engineering))--Stellenbosch University, 2008. / This thesis is concerned with the development and testing of a non-invasive device that is unassailable, and can be placed on an aggressive psychiatric patient to monitor the vital signs of this patient. Two devices, a glove measuring oxygen saturation and another on the dorsal part (back) of the patient measuring heart rate via electrocardiography (ECG), skin temperature and respiratory rate were designed and implemented. The data is transmitted using wireless technology. Both devices connect to one central monitoring station using two separate Bluetooth connections ensuring a total wireless setup. All the hardware and software to measure these variables have been designed and implemented. A Matlab graphical user interface (GUI) was developed for signal processing and monitoring of the vital signs of the psychiatric patient. Detection algorithms were implemented to detect ECG arrhythmias such as premature ventricular contraction and atrial fibrillation. The prototype was manufactured and tested in a laboratory setting on five volunteers. Satisfactory test results were obtained and the primary objectives of the thesis were fulfilled

Thesis (MScEng)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: The focus of this thesis is on South Africa's first micro space satellite SUNSAT, and the thermal modelling thereof. Background theory with relevance to thermal management and control of satellite systems and subsystems is presented. The mission profile and subsystem makeup of SUNSAT is also briefly discussed, with emphasis placed on the physical structure, possible orbit paths, internal heat generation, and the environmental heating. The environmental heating on the satellite surfaces from the direct and reflected earth solar radiation, as well as the earth emitted infrared radiation, is determined from the developed computer program ORBIT-FLUX. This program was used in tandem with numerical programs (developed in house), as well as an outsourced program TAS (Thermal Analysis Systems) to model SUNSAT for two possible orbit paths. The resistance-capacitance formulation method was used to develop the numerical programs, which served initially to establish the validity ofTAS. The first approximated thermal model of SUNSA T's batteries was the 7 lumped-mass model that focused on the batteries since their overheating is the suspected reason for SUNSA T'S failure to complete its mission. A numerical program as well as a similar TAS model was developed, and the results showed correlation to within 3°C. A lumped-mass model of SUNSAT was also developed, both numerically and using TAS. The models were tested and the results showed that the temperatures of the models were sensitive to changes in internal heating as well as varying emissivity and absorptivity. The numerical and TAS lumped-mass model results did not correlate well, possibly due to the higher number of control volumes used in the TAS lumped-mass model. The TAS SUNSAT 2 model was developed as advancement on the lumped-mass model. The higher number of control volumes and the effect of adding solar panels gave a more realistic model of SUNSA T. The results did not show good correlation with actual SUNSA T temperature data possibly due to the fact that the solar panels were not mounted on the model body as they were on SUNSA T; but the TAS SUNSA T 2 model did set the platform for the more advanced TAS SUNSAT 3 model. This thermal model included the effects of the solar panel mountings, and had a higher number of control volumes, which gave a better physical representation of the SUNSAT subsystems. The model was tested for possible orbit paths of SUNSA T. The results showed excellent correlation to actual SUNSA T data. For the comparison of the TAS SUNSA T 3 model results with data from SUNSAT for July 1999 showed that the SUNSA T battery temperature was modelled to within 8°C. And for June 2000, this same comparison was to within 1°C. A thermal management and control case study was done on a simple system (which included a cubic box and an internal solid block with heat generation) to illustrate the effects of using various passive and active thermal control hardware to regulate temperatures. The results showed that internal surfaces painted black provide for maximum heat sharing, and lowest block temperatures. The block temperatures were found to be very sensitive to changes in the cube external optical surface properties. A slight increase in emissivity lowered the block temperature, while a slight increase in absorptivity increased the block temperature. Heat pipes were also found to lower the temperatures of the block and immediate subsystems by providing a path of low thermal resistance to the flow of heat from the block directly to the radiator. The effect of thermal insulation was also investigated. For the two materials (rubber and plastic) that were tested, it was noticed that although insulation material does give more thermal control and predictability over a subsystem by thermally isolating it from its environment, it can cause a subsystem that has heat generation to become too hot. Recommendations were made relating to future micro satellite thermal management and control with regard to; thermal modelling techniques, acquisition of tried software, positioning of temperature sensors for optimisation of thermal data, and the verification of optical surface properties by physical measurement. / AFRIKAANSE OPSOMMING: Hierdie tesis fokus op Suid-Afrika se eerste mikro ruimte satelliet, SUNSAT, en die termiese ontwikkeling daarvan. Agtergrond teorie met betrekking tot die termiese bestuur en kontrole van die satelliet-sisteme en subsisteme word aangebied. Die missie-profiel en die samestelling van die subsisteme word ook kortliks bespreek met die klem op die fisiese strukture, moontlike wentelbane, interne hitte-opwekking, en die omgewingsverhitting. Die omgewingsverhitting op die oppervlaktes van die satelliet, veroorsaak deur direkte en weerkaatste aardlson bestraling, sowel as deur infrarooi bestraling afkomstig van die aarde, word bepaal deur die ontwikkelde rekenaarprogram ORBIT-FLUX. Hierdie program word gebruik in tandem met numeriese programme (intern ontwikkel), so weI as 'n uitgekontrakteerde program TAS (Termiese Analiese Sisteme) om SUNS AT vir twee moontlike wentelbane te modelleer. Die weerstandskapasitansie formuleringsmetode is gebruik om die numeriese programme te ontwikkel. Hierdie programme is oorspronklik gebruik om die validiteit van TAS vas te stel. Die eerste benaderde termiese model van SUNSAT se batterye was die 7 gekonsentreerdemassa model wat gefokus het op die batterye aangesien daar vermoed is dat oorverhitting van die batterye die rede is waarom SUNSAT nie sy missie voltooi het nie. 'n Numeriese program so weI as 'n gelyksoortige TAS model is ontwikkel en die resultate korreleer tot binne 3°C. 'n Gekonsentreerde-massa model van SUNSA T is ook ontwikkel, numeries en met gebruik van TAS. Die modelle is getoets en die resultate toon dat die temperature van die modelle gevoelig is vir veranderinge in interne hitte sowel as vir wissellende uitstralingsvermoe en absorpsievermoe, Die numeriese- en die TAS gekonsentreerde-massa model resultate het nie goed met mekaar korrelleer nie, moontlik weens die hoe aantal kontrole volumes wat in die TAS gekonsentreerde-massa model gebruik is. Die TAS SUNSA T 2 model is 'n verdere ontwikkeling van die gekonsentreerde-massa model. Die hoer aantal kontrole volumes en die byvoeging van solarpanele het tot gevolg gehad dat hierdie 'n meer realistiese model van SUNSA T is. Die resultate het nie goed gekorrelleer met die temperatuurdata van die werklike SUNSAT nie, moontlik weens die feit dat die solarpanele nie op die bakwerk monteer is, soos in die geval van SUNSA T nie. Nietemin het het die TAS SUNSAT 2 model gelei tot die meer gevorderde TAS SUNSAT 3 model. Hierdie termiese model het die solarpaneel montuur ingesluit en het 'n hoer aantal kontrole volumes gehad, wat 'n beter fisiese weergawe van die SUNSAT subsisteme tot gevolg gehad het. Die model is getoets vir moontlike wentelbane van SUNSAT. Die resultate het 'n hoe korrellasie getoon met die data van die werklike SUNSAT. 'n Vergelyking van die TAS SUNSAT 3 model resultate met data van SUNSAT vir Julie 1999 wys dat die SUNSAT battery temperatuur dieselfde is tot binne 8°C. Vergelyk met die resultate vir Junie 2000 was dit binne 1°C. 'n Termiese bestuurs- en kontrolestudie is gedoen op 'n eenvoudige sisteem (insluitende 'n kubieke boks en 'n interne soliede blok met hitte opwekking) om die uitwerking van die gebruik van passiewe en aktiewe termiese kontrole hardeware wat temperature reguleer, te illustreer. Die resultate toon dat interne oppervlaktes wat swart geverf is, lei tot die maksimum hitte-deling, en die laagste bloktemperature. Daar is gevind dat bloktemperature baie gevoelig is vir veranderinge in die eienskappe van die kubus se eksterne optiese oppervlaktes. 'n Effense vermedering van uitstralingsvermoe verlaag die bloktemperatuur, terwyl 'n effense vermedering van absorpsievermoe die bloktemperatuur verhoog. Daar is ook gevind dat hittepype die temperatuur van die blok en onmiddelike subsisteme verlaag deur om 'n pad van lae termiese weerstand teen die vloei van hitte vanaf die blok, direk na die verkoeler te verskaf. Die uitwerking van termiese isolasie is ook ondersoek. In die geval van die twee materiale (rubber en plastiek) wat getoets is, is daar opgemerk dat, alhoewel isolasie materiaal meer termiese beheer oor die subsisteem en voorspelbaarheid tot gevolg gehad het deurdat die subsisteem termies van die omgewing isoleer is, kan dit veroorsaak dat die subsisteem te warm word. Aanbevelings is gemaak met betrekking tot toekomstige mikro satelliet bestuur en kontrole en wel in verband met die volgende: termiese modelleringstegnieke, die aanskaffing van getoetste sagteware, die plasing van temperatuut sensors vir die beste termiese data, en die verifikasie van die eienskappe van optiese oppervlaktes deur fisiese meting.

Thesis (MScEng)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: Measurements on air-cooled reflux steam condensers or dephlegmators at different power plants have shown that sections of these units do not transfer heat effectively over a range of operating conditions. The ineffective sections may be due to flooding in the finned tubes although entrainment of condensate in certain steam inlet manifolds is usually the main reason for the poor performance. In this dissertation factors that limit effective dephlegmator operation are discussed and the influence of two inlet manifold designs on dephlegmator operation is investigated. Laboratory experiments are conducted to show under which conditions liquid entrainment occurs and to visualize the flow distribution within the respective manifolds. An alternative, essentially horizontal arrangement of the dephlegmator is proposed. In order to evaluate the performance of such a system, the heat transfer and pressure drop on the steam-side is determined experimentally in an air-cooled finned tube. No flooding was observed during tests conducted at zero and negative tube angles to the horizontal. / AFRIKAANSE OPSOMMING: Toetse op lugverkoelde stoom terugvloeikondensors, of deflegmators, by verskeie kragstasies het getoon dat sekere dele van hierdie eenhede onder verskeie werkstoestande nie warmte effektief oordra nie. Hierdie oneffektiewe dele kan deur vloeding van die vinbuise veroorsaak word alhoewel die meesleur van kondensaat in sekere stoom inlaatspruitstukke gewoonlik die hoof oorsaak is. In hierdie dissertasie word faktore wat effektiewe deflegmator werksverrigting beinvloed bespreek en die invloed van twee inlaatspruitstukontwerpe op deflegmator werksverrigting ondersoek. Eksperimente is in 'n laboratorium uitgevoer om aan te toon onder watter werkstoestande vloeistof samesleping voorkom en om vloeiverdeling binne die onderskeie inlaatspruitstukke te visualiseer. 'n Altematiewe, wesenlike horisontale deflegmator opstelling word voorgestel. Die werksverrigting van hierdie voorstelling is ondersoek deur die warmteoordrag en stoorn-kant drukval eksperimenteel te bepaal in 'n lugverkoelde vinbuis. Geen vloeding is opgemerk vir toetsgevalle waar klein negatiewe of zero hoeke tot die horisontaal ondersoek is nie.

Thesis (MScEng)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: Flotation was introduced early in the zo" century as a separation process for extracting valuable minerals from grinded ore. Today flotation is a dominant mineral concentration method and is used for almost all sulphide minerals and also for nonsulphide metallic minerals, industrial minerals, and coal. Automation and control has become a basic requirement in flotation plants. Effective control of pulp levels plays a very important role in stabilising the flotation process and therefore requires careful attention. This thesis presents a de-coupled level controller that has been developed for the control of levels in cascaded flow processes, including multi-tank cascaded flotation processes. The controller was developed on a two tank cascaded pilot plant using water as a flow medium. A simulation model was constructed for the cascaded flow process. The simulation model made it possible to develop and evaluate a decoupled level controller in a simulation environment. Finally independent loop PIO control and integrated PIO control loops with feed-forward de-coupling were compared through simulation, as control strategies for the pilot plant. / AFRIKAANSE OPSOMMING: Flotasie is vroeg in die 20ste eeu bekend gestel as 'n skeidingsproses om waardevolle minerale te onttrek uit fyngemaalde erts. Vandag is flotasie die dominante proses om minerale te konsentrasie en word gebruik vir byna aile sulfied minerale sowel as nie-sulfied metaal minerale, industriele minerale and steenkool. Outomatisasie en beheer het 'n basiese vereiste geword in flotasie aanlegte. Die effektiewe beheer van pulpvlakke speel 'n baie belangrike rol in die stabilisering van die flotasie proses en verdien om hierdie rede deeglike aandag. Hierdie tesis stel 'n ontkoppelde vlakbeheerstelsel voor wat ontwikkel is vir die beheer van vlakke in kaskade vloei prosesse byvoorbeeld multi-tenk flotasie prosesse. Die beheerstelsel is ontwikkel op 'n twee-tenk kaskade toetsaanleg met water as vloeimedium. 'n Volledige simulasiemodel is ontwikkel wat dit moontlik gemaak het om die vlakbeheerstelsel te ontwerp, toets en verfyn in 'n simulasie omgewing. Verder is die verskil tussen onafhanklike enkellus PID beheerders en ontkoppelde PID beheerlusse ondersoek en word in die tesis geillustreer.

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2011. / 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 slegs binnenshuis gebruik kan word. Onlangse ontwikkelings in sensor tegnologie het egter gelei na die beskikbaarheid van traagheids-BWS-tegnologie (TBT). TBT gebruik traagheidsmetingseenhede (TMEs) wat aan 'n persoon se liggaam aangeheg kan word om die kinematika te verkry sonder enige eksterne sensore. TBT is dus volkome draagbaar, wat nuwe geleenthede skep vir kliniese bewingsanalises. Hierdie projek evalueer die gebruik van TBT vir die verbetering van fietsry kinematika. Tien kompeterende fietsryers (manlik) was getoets met 'n TBT terwyl hulle teen 2, 3.5 and 5.5 W.kg-1 gery het op 'n pad, en op 'n stilstaande oefenfietsraam. 'n Maatstaftoets was ook uitgevoer waar fietsry-kinematika gelyktydig met die TBT en die Vicon optiese BWS opgeneem was. Die eerste doel van die navorsing was om die moontlikheid te ondersoek of fietsryer kinematika op die pad gemeet kan word. Die resultate toon dat die ferro-magnetiese materiale wat in meeste padfietse voorkom, 'n beduidende magnetiese steuring (tot 50% afwyking in intensiteit) op die TMEs naby die pedale en handvatsels veroorsaak, wat lei tot aansienlike foute in die kinematiese metings. Gevolglik was dit gevind dat die TBT nie volle-liggaam kinematika op 'n fiets kan meet nie. Nogtans, het die resultate van die Vicon maatstaftoets bewys dat die TBT nog steeds akkurate heup (wortel van die gemiddelde kwadraad fout (WGKF) < 1°), knie (WGKF < 4°) en enkel (WGKF < 3°) fleksie kan meet met die “Kinematiese Koppeling” algoritme. Die tweede doel was om te bepaal of daar 'n beduidende verskil tussen die laboratorium en pad fietsry-kinematika is. Die buitelug fleksie data het beduidend verskil van die binnenshuise resultate, veral vir minimum fleksie (P < 0.05 vir alle gewrigte). Veranderinge in fietsryer kinematika tussen hoë en lae krag het ook beduidend meer variasie op die pad (R2 = 0.36, 0.61, 0.08) as op die oefenfietsraam (R2 = 0.93, 0.89, 0.56) vir die heup, knie en enkel gewrigte, onderskeidelik, gehad. Hierdie resultate bevraagteken die ekologiese geldigheid van kinematiese toetse op fietsryers in 'n laboratorium. 'n Laaste doel was om die toepassings van TBT vir die optimering van fietsry kinematika te ondersoek. 'n Verskeidenheid aspekte van die analise en verbetering van fietsry kinematika met die TBT word bespreek. Die gevolgtrekking is dat TBT geskik is vir gebruik as 'n dinamiese instrument vir die analise van biomeganiese doetreffendheid, bilaterale asimmetrie en die voorkoming van beserings. Aanbevelings vir toekomstige werk, sluit in die uitskakeling van die magnetiese inmenging, asook die integrasie van die TBT data met kinetiese metings.

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: This thesis gives a cost model for the manufacture of bipolar plates in South Africa. The methods for the manufacture considered are machining, using a micro-milling machine, and compression moulding. The focus of this thesis is on compression moulding. Details of the work done towards developing and validating the models are described, and then the cost models are discussed in detail. The results of the analysis done using the cost model is given with attention paid to the effect of changing design parameters, such as channel size and flow field area, and of the cost of production for both methods over various production volumes. The thesis concludes that compression moulding becomes the better option for production volumes greater than 324 bipolar plates, with a cost that eventually reaches close to R140 per plate for high enough production volumes (over 5000). The cost to produce 1000 plates using compression moulding is estimated at R294 per plate. An increase of the channel size gives a small reduction in the total cost, while the increase in cost with an increase in flow field area is large. / AFRIKAANSE OPSOMMING: Hierdie tesis gee 'n koste-model vir die vervaardiging van bipolêre plate in Suid- Afrika. Die vervaardigingsmetodes wat oorweeg word, is masjinering deur 'n mikro-freesmasjien en persvorming. Die fokus van hierdie tesis is op persvorming. Die besonderhede van die ontwikkeling en validering van die modelle word beskryf, en daarna word die modelle in besonderhede beskryf. Die resultate van 'n analise wat met die koste-model gedoen is, word daarna gegee, met die oorweging van die verandering van ontwerp-parameters soos die vloeikanaalgrootte en vloeiveld-area, en van die koste van vervaardiging vir beide metodes vir verskeie produksievolumes. Die tesis kom tot die slotsom dat persvorming die voorkeurproses is vir produksievolumes groter as 324 bipolêre plate, met 'n koste wat tot naastenby R140 per plaat daal vir hoë produksievolumes (meer as 5000). Die koste om 1000 plate met persvorming te maak, word op R294 per plaat beraam. 'n Toename in kanaalgrootte gee 'n klein vermindering in die totale koste, terwyl die toename in koste groot is wanneer die vloeiveld-area toeneem.

Thesis (MScEng)--Stellenbosch University, 2012. / 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 beskryf die proses vir die ontwikkeling van ’n gebruikerskoppelvlak vir ’n sewevryheidsgraad-, minimaal indringende chirurgiese robot. In die eerste twee hoofstadia van die algehele projek, voltooi deur ander studente, is ’n primêre slaafmanipuleerder (PSM) en ’n sekondêre slaafmanipuleerder (SSM) ontwikkel. Die stadium in hierdie tesis konsentreer op die skep van ’n stuurstok waarmee die gekombineerde beweging van die PSM en SSM beheer kan word. Agtergrondinligting oor die gebied van robotiese chirurgie word verskaf, met spesifieke verwysing na die gebruikerskoppelvlakke van huidige stelsels, en die spesifikasies van die PSM en SSM word vasgestel. Daarna volg die beweegrede sowel as die belangrikste oogmerke van die projek. Die oogmerke is in die hoofafdelings van meganiese ontwerp, elektroniese ontwerp, beheerstelselontwerp en toetsing verdeel. Die meganiese ontwerp van die stuurstok behels ’n konsepontwikkelingstadium, wat uitloop op ’n finale sewevryheidsgraad-ontwerp, wat dan op grond van ingenieurspesifikasies aangebied en beoordeel word. Aluminium word as boumateriaal gebruik; elektromagnetiese remme word vir elke koppeling gespesifiseer, en die finale samestel is ’n gekonstrueerde stuurstok wat aan alle vereistes voldoen. Die elektroniese ontwerp behels die gebruik van magnetiese draaikodeerders om die stuurstok se posisie en oriëntasie te bepaal, sowel as meganismes met die nodige krag- en beheerstroombaanwerk om die stuurstok reg te laat funksioneer. ’n Koppelvlak tussen die PSM en die SSM moes suksesvolle kommunikasie tussen die meester en die slaaf bewerkstellig. Verskeie nodige aanpassings is dus aan die slaafstelsel aangebring, waarna die stuurstok en robot elektronies gekoppel is om ’n direkte reekskommunikasielyn te skep. Vir beheerstelselontwerp is die stuurstok en robot volgens die Denavit- Hartenberg-beginsel gemodelleer, wat ’n direkte verhouding tussen die posisie en oriëntasie van die onderskeie eindpunt-effektors aan die stuurstok- en robotkant daarstel. Voorwaartse kinematiese vergelykings is daarna op die stuurstok toegepas; die gewenste posisie en oriëntasie van die robotiese eindpunt-effektor is bepaal, waarna terugwaartse kinematiese vergelykings op hierdie data toegepas is om die robot se koppelingveranderlikes te bepaal. Hierdie afdeling word afgesluit met die ontwikkeling van twee bedryfsmodusse: een waar slegs die SSM-motore beheer word sodat die slaaf die meester se bewegings kan navolg, en die ander waar die PSM se motore afsonderlik beheer word. Die gelyktydige beheer van al die robotmotore kon nie getoon word nie weens fundamentele meganiese tekortkominge in die PSM- en SSM-ontwerp. Laastens is ’n toets uitgevoer om die bewegingsbeheer van die robot deur die stuurstok te toon. Die intuïtiwiteit van die produk is ook suksesvol getoets. Die studie sluit af met die projekgevolgtrekkings, waarvan die belangrikste die suksesvolle ontwikkeling en toetsing van ’n stuurstok is wat daarin slaag om die beweging van ’n chirurgiese robot te beheer, sowel as die verwesenliking van alle hoofprojekoogmerke.

Thesis (MScEng)--Stellenbosch University, 2013. / 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.

Thesis (MScEng)--Stellenbosch University, 2013. / 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 beskrywing van toekomstige werk wat gedoen kan word indien die konsep ontwikkel word tot 'n bemarkbare produk.