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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
241

Optimization-based Assistive Controllers in Teleoperation of Mobile Robotic Manipulators

Rahnamaei, Saman 10 1900 (has links)
<p>This thesis investigates two significant problems in control and coordination of complex teleoperation systems as they relate to the operation of a mobile robotic manipulator. The first part of the thesis focuses on the design of a control framework to resolve kinematic redundancy in teleoperation of a mobile robotic manipulator. Apart from the redundancy, workspace considerations for the operator and robot and asymmetry of master and slave systems pose significant design challenges in such telerobotic systems . The second part of the thesis considers psychophysical aspects of teleoperation from the operator's perspective. This part presents a method for automatic {\em optimal} positioning of a single camera for a remotely navigated mobile robot in systems with a controllable camera platform. In each part, a constrained optimization problem is formulated and solved in real time. The solution of these optimization problems are integrated seamlessly into the teleoperation control framework in order to assist the operator in accomplishing the main task. The proposed control framework in the first part allows the operator to concentrate on the manipulation task while the mobile base and arm joint configurations are automatically {\em optimized} according to the needs of the task. Autonomous control subtasks are defined to guide the base and the arms towards this optimal configuration while the operator teleoperates the end-effector(s) of the mobile arm(s). The teleoperation and autonomous control tasks have adjustable relative priorities set by the system designer. The work in the second part enables the operator to focus mainly on navigation and manipulation while the camera viewpoint is automatically adjusted. The workspace and motion limits of the camera system and the location of the obstacles are taken into consideration in camera view planning. A head tracking system enables the operator to use his/her head movements as an extra control input to guide the camera placement, if and when necessary. Both proposed controllers have been implemented and evaluated in teleoperation experiments and user studies. The results of these experiments confirm the effectiveness of these controllers and demonstrate significant improvements compared to other existing controllers from the literature included in the studies.</p> / Master of Applied Science (MASc)
242

Optimal Driver Risk Modeling

Mao, Huiying 21 August 2019 (has links)
The importance of traffic safety has prompted considerable research on predicting driver risk and evaluating the impact of risk factors. Driver risk modeling is challenging due to the rarity of motor vehicle crashes and heterogeneity in individual driver risk. Statistical modeling and analysis of such driver data are often associated with Big Data, considerable noise, and lacking informative predictors. This dissertation aims to develop several systematic techniques for traffic safety modeling, including finite sample bias correction, decision-adjusted modeling, and effective risk factor construction. Poisson and negative binomial regression models are primary statistical analysis tools for traffic safety evaluation. The regression parameter estimation could suffer from the finite sample bias when the event frequency (e.g., the total number of crashes) is low, which is commonly observed in safety research. Through comprehensive simulation and two case studies, it is found that bias adjustment can provide more accurate estimation when evaluating the impacts of crash risk factors. I also propose a decision-adjusted approach to construct an optimal kinematic-based driver risk prediction model. Decision-adjusted modeling fills the gap between conventional modeling methods and the decision-making perspective, i.e., on how the estimated model will be used. The key of the proposed method is to enable a decision-oriented objective function to properly adjust model estimation by selecting the optimal threshold for kinematic signatures and other model parameters. The decision-adjusted driver-risk prediction framework can outperform a general model selection rule such as the area under the curve (AUC), especially when predicting a small percentage of high-risk drivers. For the third part, I develop a Multi-stratum Iterative Central Composite Design (miCCD) approach to effectively search for the optimal solution of any "black box" function in high dimensional space. Here the "black box" means that the specific formulation of the objective function is unknown or is complicated. The miCCD approach has two major parts: a multi-start scheme and local optimization. The multi-start scheme finds multiple adequate points to start with using space-filling designs (e.g. Latin hypercube sampling). For each adequate starting point, iterative CCD converges to the local optimum. The miCCD is able to determine the optimal threshold of the kinematic signature as a function of the driving speed. / Doctor of Philosophy / When riding in a vehicle, it is common to have personal judgement about whether the driver is safe or risky. The drivers’ behavior may affect your opinion, for example, you may think a driver who frequently hard brakes during one trip is a risky driver, or perhaps a driver who almost took a turn too tightly may be deemed unsafe, but you do not know how much riskier these drivers are compared to an experienced driver. The goal of this dissertation is to show that it is possible to quantify driver risk using data and statistical methods. Risk quantification is not an easy task as crashes are rare and random events. The wildest driver may have no crashes involved in his/her driving history. The rareness and randomness of crash occurrence pose great challenges for driver risk modeling. The second chapter of this dissertation deals with the rare-event issue and provides more accurate estimation. Hard braking, rapid starts, and sharp turns are signs of risky driving behavior. How often these signals occur in a driver’s day-to-day driving reflects their driving habits, which is helpful in modeling driver risk. What magnitude of deceleration would be counted as a hard brake? How hard of a corner would be useful in predicting high-risk drivers? The third and fourth chapter of this dissertation attempt to find the optimal threshold and quantify how much these signals contribute to the assessment of the driver risk. In Chapter 3, I propose to choose the threshold based on the specific application scenario. In Chapter 4, I consider the threshold under different speed limit conditions. The modeling and results of this dissertation will be beneficial for driver fleet safety management, insurance services, and driver education programs.
243

Wheel movement during braking

Klaps, J., Day, Andrew J. January 2002 (has links)
Yes / An experimental study of wheel movement arising from compliance in the front suspension and steering system of a passenger car during braking is presented. Using a Kinematic and Compliance (K&C) test rig, movement of the front wheels and the suspension sub-frame, together with corresponding changes in suspension / steering geometry under simulated braking conditions, were measured and compared with dynamic measurements of the centre points of the front wheels. The resulting knowledge of front wheel deflections has enabled the causes and effects of steering drift during braking to be better understood in the design of front suspension systems for vehicle stability.
244

Emplacement of the Santa Rita Flat pluton and kinematic analysis of cross cutting shear zones, eastern California

Vines, John Ashley 05 January 2000 (has links)
This study documents the deformation history of the Santa Rita Flat pluton, eastern California, from the time of emplacement to post-emplacement transpressional shearing, and consists of manuscripts that make up three chapters. The first chapter addresses the emplacement of the Santa Rita Flat pluton using anisotropy of magnetic susceptibility (AMS). The second chapter describes the kinematic analysis of cross-cutting shear zones within the western margin of the pluton. The third chapter is an informal paper on the U/Pb dating of two sheared felsic dikes from the pluton. AMS of the Santa Rita Flat pluton indicates that the paramagnetic and ferromagnetic minerals define a foliation which is arched into an antiformal structure in the central to southern parts of the pluton. The northern part of the pluton displays an east-west striking magnetic foliation which lacks a fold-like geometry. Previously published field mapping and petrologic surveys of the pluton and surrounding wall rocks indicate that the southern margin and northern part of the Santa Rita Flat pluton represents the roof and core of the pluton, respectively. Integration of our analysis of the internal structure of the pluton with previously published work on the regional structure of the surrounding metasedimentary wall rocks, suggests that the pluton may have initially been intruded as a sill-like or "saddle reef" structure along a stratigraphically controlled mechanical discontinuity in the hinge zone of an enveloping regional-scale synform. Subsequent vertical inflation of this sill resulted in local upward doming of the overlying pluton roof and formation of the antiformal structure now observed at the current erosion level in the central-southern part of the pluton and overlying locally preserved roof rocks. No corresponding fold structure is indicated by AMS analysis in the northern part of the pluton, which is exposed at a deeper level, and represents a section closer to the pluton core. Emplacement of the Santa Rita Flat pluton at 164 Ma overlaps in time with regional deformation at ~185 - ~148 Ma (Middle - Late Jurassic) recognized in the southern Inyo Mountains. Northwest trending folds are pervasive along the western flank of the Inyo and White Mountains, and may have accommodated strains at the lateral tips of thrust faults which crop out in the southern Inyo Mountains. We speculate that space for initial emplacement of the Santa Rita Flat pluton may have been produced by layer-parallel slip and hinge-zone dilation, accompanied by axis-parallel slip during formation of a regional scale thrust-related synform. The Santa Rita shear system (SRSS) is composed of a series of discrete NW-SE striking steeply dipping shear zones that cut and plastically deform granitic rocks of the Santa Rita Flat pluton. The shear zones exhibit a domainal distribution of gently and steeply plunging stretching lineations, and are located at planar mechanical discontinuities between the granite and a series of felsic/mafic dikes which intrude the pluton. Mylonitized dikes within the shear zones contain syntectonic mineral assemblages not observed in dikes outside the shear zones, indicating that the dikes were intruded prior to shear zone development. Correlation with geometrically similar shear zones in the Sierra Nevada batholith to the west, suggests that the SRSS probably nucleated from a regional stress field in Cretaceous times (~90-78 Ma). Strain is heterogeneous within the shear zones, with local development of protomylonite, mylonite, ultramylonite and phyllonite. Strain heterogeneity within the granite is attributed to fluid infiltration and chemical reaction and alteration of feldspar to fine-grained mica. These deformation-induced mineral changes would have resulted in progressive mechanical weakening over time of rocks within the SRSS. The phyllonites occur predominantly within steeply lineated shear zones and contain mylonitized foliation-parallel quartz veins. The pattern of c-axis preferred orientation in these quartz veins indicates that deformation within the shear zones occurred under plane strain conditions. Locally, quartz veins also cut the foliation planes, reflecting high pore fluid pressures during evolution of the SRSS. These cross-cutting quartz veins are also plastically deformed, and their c-axis patterns indicate weak constrictional strains. The orientation of the shear zones, together with their strain paths, are used to develop a transpressional kinematic model for development of the SRSS within a progressively rotating stress field. / Master of Science
245

Development of a Next-generation Experimental Robotic Vehicle (NERV) that Supports Intelligent and Autonomous Systems Research

Baity, Sean Marshall 06 January 2006 (has links)
Recent advances in technology have enabled the development of truly autonomous ground vehicles capable of performing complex navigation tasks. As a result, the demand for practical unmanned ground vehicle (UGV) systems has increased dramatically in recent years. Central to these developments is maturation of emerging mobile robotic intelligent and autonomous capability. While the progress UGV technology has been substantial, there are many challenges that still face unmanned vehicle system developers. Foremost is the improvement of perception hardware and intelligent software that supports the evolution of UGV capability. The development of a Next-generation Experimentation Robotic Vehicle (NERV) serves to provide a small UGV baseline platform supporting experimentation focused on progression of the state-of-the-art in unmanned systems. Supporting research and user feedback highlight the needs that provide justification for an advanced small UGV research platform. Primarily, such a vehicle must be based upon open and technology independent system architecture while exhibiting improved mobility over relatively structured terrain. To this end, a theoretical kinematic model is presented for a novel two-body multi degree-of-freedom, four-wheel drive, small UGV platform. The efficacy of the theoretical kinematic model was validated through computer simulation and experimentation on a full-scale proof-of-concept mobile robotic platform. The kinematic model provides the foundation for autonomous multi-body control. Further, a modular system level design based upon the concepts of the Joint Architecture for Unmanned Systems (JAUS) is offered as an open architecture model providing a scalable system integration solution. Together these elements provide a blueprint for the development of a small UGV capable of supporting the needs of a wide range of leading-edge intelligent system research initiatives. / Master of Science
246

Modélisation couplée tectonique et processus de surface de l'extension et l'inversion dans les Pyrénées / Spatial and temporal coupling between tectonics and surface processes during lithosphere inversion of the Pyrenean-Cantabrian Mountain belt : contraints from exhumation histories and surface process modelling

Erdös, Zoltan 26 September 2014 (has links)
Orogenic belts are fundamental features of plate tectonics. The crustal structure of orogens around the world shows a wide range of deformation styles from narrow, asymmetric wedges like the Pyrenees to wide, plateau-like orogens such as the Zagros or the Himalaya. The primary controlling factor on the size and structure of an orogen is the amount of convergence between the colliding plates. However, there are important additional factors providing major controls on the structural development of orogens. Among the potential parameters that can affect the style of deformation are the crustal strength, inherited weaknesses, and the surface processes. These parameters have been studied extensively in the past but their relative importance remains unclear. The aim of this thesis is to improve our understanding of: (1) How surface processes affect mountain building, with a special focus on the relationship between thin-skinned foreland and thick-skinned internal deformation of orogens. (2) How inherited extensional structures affect mountain building. The study was carried out using the Pyrenees as a special reference case. To answer our research questions we have used a wide range of state-of-the-art numerical modelling tools. In paper 1 we present a new method where we couple a structural-kinematic model and a thermo-kinematic model to evaluate the consistency of existing balanced section reconstructions with independent thermochronology data. In papers 2 and 3 we use 2D lithospheric scale thermo-mechanical models with surface process algorithms. Using the above toolset, we demonstrate that syntectonic sedimentation results in longer basement thrust sheets as well as longer thin-skinned thrust sheets and a generally wider orogen. Conversely erosion tends to narrow the wedge and reduce the orogenic loading of the colliding plates, limiting the space available for deposition in the flexural foreland deeps. We also demonstrate that inherited extensional structures play a crucial role in mountain building as they facilitate the migration of deformation into the undeformed basement of the overriding plate. Moreover, a significant amount of lower-crustal/mantle-lithospheric material is preserved at shallow depths only in the presence of extensional inheritance, but significant erosion is needed in order to bring this material to the surface. Our models also show that thin-skinned thrust sheets are generally rooted in the footwall of basement thrusts as they form outward-propagating sequences. As soon as a new basement thrust forms, the thin-skinned sequence situated on top of the new basement thrust-sheet is abandoned in favour of starting a new sequence in the footwall of the new thrust. Regarding our case study, it was possible to reproduce the section restoration using a structural-kinematic model with high accuracy up to the 36-Ma time slice and with limited accuracy up to the 50-Ma time slice. The thermochronometric ages predicted by the thermo-kinematic modelling are generally in good agreement with both the high- and low-temperature thermochronology data available in the Central Pyrenees; hence we conclude that the restoration is to a first order consistent with these datasets. The predicted thermochronological ages approximate the available low-temperature thermochronology data better by taking into account the late-stage burial and re-excavation scenario affecting the southern flank of the Pyrenean wedge presented by Coney et al. (1996), and quantified by Fillon and van der Beek (2012). In conclusion, our model experiments suggest, that extensional inheritance played a prime role in the structural evolution of the Pyrenees, with the major characteristics of the North Pyrenean Unit, including the presence of steep, inverted normal faults, the relative tectonic quiescence of the area after the early inversion and the presence of a lower-crustal body at shallow depth below the unit, best recaptured by our accordion models. / Orogenic belts are fundamental features of plate tectonics. The crustal structure of orogens around the world shows a wide range of deformation styles from narrow, asymmetric wedges like the Pyrenees to wide, plateau-like orogens such as the Zagros or the Himalaya. The primary controlling factor on the size and structure of an orogen is the amount of convergence between the colliding plates. However, there are important additional factors providing major controls on the structural development of orogens. Among the potential parameters that can affect the style of deformation are the crustal strength, inherited weaknesses, and the surface processes. These parameters have been studied extensively in the past but their relative importance remains unclear. The aim of this thesis is to improve our understanding of: (1) How surface processes affect mountain building, with a special focus on the relationship between thin-skinned foreland and thick-skinned internal deformation of orogens. (2) How inherited extensional structures affect mountain building. The study was carried out using the Pyrenees as a special reference case. To answer our research questions we have used a wide range of state-of-the-art numerical modelling tools. In paper 1 we present a new method where we couple a structural-kinematic model and a thermo-kinematic model to evaluate the consistency of existing balanced section reconstructions with independent thermochronology data. In papers 2 and 3 we use 2D lithospheric scale thermo-mechanical models with surface process algorithms. Using the above toolset, we demonstrate that syntectonic sedimentation results in longer basement thrust sheets as well as longer thin-skinned thrust sheets and a generally wider orogen. Conversely erosion tends to narrow the wedge and reduce the orogenic loading of the colliding plates, limiting the space available for deposition in the flexural foreland deeps. We also demonstrate that inherited extensional structures play a crucial role in mountain building as they facilitate the migration of deformation into the undeformed basement of the overriding plate. Moreover, a significant amount of lower-crustal/mantle-lithospheric material is preserved at shallow depths only in the presence of extensional inheritance, but significant erosion is needed in order to bring this material to the surface. Our models also show that thin-skinned thrust sheets are generally rooted in the footwall of basement thrusts as they form outward-propagating sequences. As soon as a new basement thrust forms, the thin-skinned sequence situated on top of the new basement thrust-sheet is abandoned in favour of starting a new sequence in the footwall of the new thrust. Regarding our case study, it was possible to reproduce the section restoration using a structural-kinematic model with high accuracy up to the 36-Ma time slice and with limited accuracy up to the 50-Ma time slice. The thermochronometric ages predicted by the thermo-kinematic modelling are generally in good agreement with both the high- and low-temperature thermochronology data available in the Central Pyrenees; hence we conclude that the restoration is to a first order consistent with these datasets. The predicted thermochronological ages approximate the available low-temperature thermochronology data better by taking into account the late-stage burial and re-excavation scenario affecting the southern flank of the Pyrenean wedge presented by Coney et al. (1996), and quantified by Fillon and van der Beek (2012). In conclusion, our model experiments suggest, that extensional inheritance played a prime role in the structural evolution of the Pyrenees, with the major characteristics of the North Pyrenean Unit, including the presence of steep, inverted normal faults, the relative tectonic quiescence of the area after the early inversion and the presence of a lower-crustal body at shallow depth below the unit, best recaptured by our accordion models.
247

Lineární jednotka s elektrickým pohonem pro robot s paralelní kinematickou strukturou / AC electric linear drive for paralell kinematics structures of robots

Nejedlý, Petr January 2011 (has links)
Design of linear actuator for parallel kinematic structure is described in this master´s thesis. The parallel kinematic structure is described in the first part. Open kinematics structure and close kinematics structure are compared. Their benefits and disadvantages are also mentioned. Construction of some parallel robots is illustrated. Linear actuators of different company are described. Mechanical parameters and construction of linear actuator are compared. Design of linear actuator is described in practical part of master´s thesis. A few variation of linear actuator are introduced. Individual variants are evaluated by Multicriteria Decisional Analysis and a final conception is selected. Final conception of linear actuator is elaborated. Reasons for selection of every part of linear actuator are given and basic mechanical calculation design part is made. FEA analysis of the structural part of linear actuator is made. Design of linear actuator is evaluated in the final part.
248

Synthesis of the Complete Inverse Kinematic Model of Non-Redundant Open-Chain Robotic Systems using Groebner Basis Theory

Guzmán Giménez, José 03 March 2022 (has links)
[ES] Uno de los elementos más importantes en el sistema de control de un robot es su Modelo Cinemático Inverso (IKM, por sus siglas en inglés), el cual calcula las referencias de posición y velocidad requeridas para que dicho robot pueda seguir una trayectoria. Los métodos más comúnmente empleados para la síntesis del IKM de sistemas robotizados de cadena cinemática abierta dependen fuertemente de la geometría del robot, por lo que no son procedimientos sistemáticos que puedan ser aplicados uniformemente en todas las situaciones. Este proyecto presenta el desarrollo de un procedimiento sistemático para la síntesis del IKM completo de sistemas robotizados no redundantes de cadena cinemática abierta usando la teoría de Bases de Groebner, el cual no depende de la geometría del robot. Las entradas del procedimiento desarrollado son los parámetros de Denavit-Hartenberg del robot y el rango de movimiento de sus actuadores, mientras que la salida es el IKM sintetizado, listo para ser usado en el sistema de control del robot o en una simulación de su funcionamiento. El desempeño del procedimiento desarrollado fue demostrado sintetizando los IKMs de un manipulador PUMA y un hexápodo caminante. Los tiempos de ejecución de ambos IKMs son comparables con los requeridos por los modelos cinemáticos calculados por procedimientos tradicionales, y los errores de las referencias que ofrecen como salida son totalmente despreciables. Los IKMs sintetizados son completos, porque no sólo ofrecen las referencias de posición para todos los actuadores del robot, sino que también calculan las correspondientes referencias de velocidades y aceleraciones de dichos actuadores, por lo que el procedimiento desarrollado puede ser empleado en una amplia variedad de sistemas robotizados. / [CA] Un dels elements més importants en el sistema de control d'un robot és el seu Model Cinemàtic Invers (IKM, per les seues sigles en anglés), el qual calcula les referències de posició i velocitat requerides perquè aquest robot puga seguir una trajectòria. Els mètodes més comunament emprats per a la síntesi del IKM de sistemes robotitzats de cadena cinemàtica oberta depenen fortament de la geometria del robot analitzat, per la qual cosa no són procediments sistemàtics que puguen ser aplicats uniformement en totes les situacions. Aquest projecte presenta el desenvolupament d'un procediment sistemàtic per a la síntesi del IKM complet de sistemes robotitzats no redundants de cadena cinemàtica oberta usant la teoria de Bases de Groebner, el qual no depén de la geometria del robot. Les entrades del procediment desenvolupat són els paràmetres de Denavit-Hartenberg del robot i el rang de moviment dels seus actuadors, mentre que l'eixida és el IKM sintetitzat, llest per a ser usat en el sistema de control del robot o en una simulació del seu funcionament. L'acompliment del procediment desenvolupat va ser demostrat sintetitzant els IKMs d'un manipulador PUMA i un robot caminante. Els temps d'execució de tots dos IKMs són comparables amb els requerits pels models cinemàtics calculats per procediments tradicionals, i els errors de les referències que ofereixen com a eixida són totalment menyspreables. Els IKMs sintetitzats són complets, perquè no sols ofereixen les referències de posició per a tots els actuadors del robot, sinó que també calculen les corresponents referències de velocitats i acceleracions d'aquests actuadors, per la qual cosa el procediment desenvolupat pot ser emprat en una àmplia varietat de sistemes robotitzats. / [EN] One of the most important elements of a robot's control system is its Inverse Kinematic Model (IKM), which calculates the position and velocity references required by the robot's actuators to follow a trajectory. The methods that are commonly used to synthesize the IKM of open-chain robotic systems strongly depend on the geometry of the analyzed robot, so they are not systematic procedures that can be applied equally in all situations. This project presents the development of a systematic procedure to synthesize the complete IKM of non-redundant open-chain robotic systems using Groebner Basis theory, which does not depend on the robot's geometry. The inputs to the developed procedure are the robot's Denavit-Hartenberg parameters and the movement range of its actuators, while the output is the IKM, ready to be used in the robot's control system or in a simulation of its behavior. This procedure's performance was proved synthesizing the IKMs of a PUMA manipulator and a walking hexapod robot. The computation times of both IKMs are comparable to those required by the kinematic models calculated by traditional methods, while the errors of their computed references were absolutely negligible. The synthesized IKMs are complete in the sense that they not only supply the position reference for all the robot's actuators, but also the corresponding references for their velocities and accelerations, so the developed procedure can be used in a wide range of robotic systems. / Guzmán Giménez, J. (2022). Synthesis of the Complete Inverse Kinematic Model of Non-Redundant Open-Chain Robotic Systems using Groebner Basis Theory [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/181632 / TESIS
249

A study for the development of a laser tracking system utilizing multilateration for high accuracy dimensional metrology

Greeff, Gabriel Pieter 03 1900 (has links)
MScEng / Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Accurate dimensional measurement devices are critical for international industrial competitiveness for South Africa. An overview of all the necessary components of a laser tracking system using a multilateration technique for very accurate dimensional metrology is presented. A prototype laser tracker station was built to further investigate this type of system. The prototype successfully tracks a target within a volume of at least 200 200 200 mm3, approximately 300 mm away from the tracker. This system includes the mechanical design of a prototype tracker station, electronic implementation of ampli cation and motor control circuits, a tracking control algorithm, microcontroller programming and interfacing, as well as a user interface. Kinematic modelling along with Monte Carlo analyses nd the main error source of such a tracker as the beam steering mechanism gimbal axes misalignment. Multilateration is also motivated by the results found by the analysis. Furthermore, an initial sequential multilateration algorithm is developed and tested. The results of these tests are promising and motivate the use of multilateration over a single beam laser tracking system. / AFRIKAANSE OPSOMMING: Dit is van kritieke belang dat Suid-Afrika akkurate dimensionele metingstoestelle ontwikkel vir internasionale industriële medinging. 'n Oorsig van al die nodige komponente vir 'n Laser-Volgsisteem, wat slegs van multilaterasie gebruik maak om baie akkurate drie dimensionele metings te kan neem, word in hierdie projek voorgestel. 'n Prototipe Laser-Volgsisteem-stasie word gebou om so 'n sisteem verder te ondersoek. Die prototipe slaag wel daarin om 'n teiken, binne 'n volume van 200 200 200 mm3 op 'n afstand van omtrent 300 mm te volg. Die sisteem sluit die meganiese ontwerp van die sodanige stasie, elektroniese seinversterking, motorbeheer, 'n volgingsbeheer algoritme, mikroverwerker programeering en intergrasie, asook 'n gebruikerskoppelvlak program in. Kinematiese modelering, tesame met Monte Carlo simulasies, toon aan dat die hoof oorsaak van metingsfoute by so 'n stasie by die rotasie-asse van die laserstraal-stuurmeganisme, wat nie haaks is nie, lê. Die multilaterasie metode word ook verder ondersteun deur dié modelering. 'n Algoritme wat sekwensiële multilateratsie toepas word boonop ontwikkel en getoets. Die resultate van die toetse dui daarop dat die algoritme funksioneer en dat daar voordele daarin kan wees om so 'n metode in plaas van 'n Enkelstraal-Volgsisteem te gebruik.
250

The design, kinematics and error modelling of a novel micro-CMM parallel manipulator

Rugbani, Ali Milud 04 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The research presented in this dissertation establishes a micro-CMM parallel manipulator as a viable positioning device for three degree of freedom micro measurement applications. The machine offers the advantages associated with parallel kinematic manipulators, such as light carrying weight, high stiffness and no accumulation of errors, while avoiding some of the traditional disadvantages of parallel manipulators such as the associated effects of angular errors (Abbé error), singularity problems, work space limitation and the extensive use of spherical joints. In this dissertation, the direct position kinematic solution is developed analytically and the solution of the inverse position kinematic is solved numerically. A workspace analysis has been performed. A fully functional prototype demonstrator is fabricated to demonstrate this machine. While the demonstrator was not intended to achieve submicron accuracy, it was intended to validate the error models. Computer controlled measurement is developed and used to position the probe and to record measurements. A reliable kinematic error model based on the theory of error propagation is derived analytically. A numerical method is used to verify the analytical results. Comparison shows that the results of the error model, both analytical and numerical, represent a very good match and follow the same trend. The kinematic position model is validated using a conventional CMM. Results show that an average difference of less than 0.5 mm over a set of 30 points is achieved. This result of the micro-CMM demonstrator measurements falls within the error budget of approximately 0.75 mm estimated by the proposed analytical error model. / AFRIKAANSE OPSOMMING: Die navorsing in hierdie tesis vestig ‘n mikro-CMM parallelle manipuleerder as ‘n lewensvatbare posisioneringstoestel vir drie vryheidsgraad-mikrometing toepassings. Die masjien bied voordele geassosieer met parallelle kinematiese manipuleerders, bv. ligte dra-gewig, hoë styfheid en geen ophoping van foute nie. Die tradisionele nadele van parallelle manipuleerders soos die geassosieerde gevolge van hoekfoute (Abbé fout), enkelvoudigheidsprobleme, werkspasiebeperking en die uitgebreide gebruik van sferiese koppelings word vermy. In hierdie tesis word die direkte posisie kinematiese oplossing analities ontwikkel en die oplossing van die omgekeerde posisie kinematies word numeries opgelos. ‘n Werkspasie analise is uitgevoer. ‘n Ten volle funksionele prototipe demonstrasie-model is vervaardig om hierdie masjien te demonstreer. Die model is nie vervaardig om submikron akkuraatheid te bereik nie, maar eerder om foutmodelle geldig te verklaar. Rekenaar-beheerde metings is ontwerp en gebruik om die toetspen te posisioneer en om metings te neem. ‘n Betroubare kinematiese foutmodel gebaseer op die teorie van foutvoortplanting is analities afgelei. ‘n Numeriese metode word gebruik om die analitiese resultate te bevestig. Vergelyking toon aan dat die resultate van die foutmodel, beide analities en numeries, goeie pasmaats is en dieselfde tendens volg. Die kinematiese posisie model word geldig verklaar deur gebruik te maak van ‘n konvensionele CMM. Resultate wys dat daar ‘n gemiddelde verskil van minder as 0.5 mm oor ‘n stel van 30 punte behaal word. Die resultate van die mikro-CMM model se metings val binne die foutbegroting van ongeveer 0.75 mm geskat by die voorgestelde analitiese foutmodel.

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