Dissertations / Theses on the topic 'Wheel base'

Sur une maquette à l’échelle 2/5ième équipée d’un diffuseur et de pneus Michelin. La géométrie du véhicule, basée sur le modèle ASMO, a été modifiée précédemment à ce travail afin d’obtenir un angle d’attaque de l’écoulement sur les roues avant et un équilibre du sillage réaliste en présence de quatre roues tournantes. Cette configuration a servi de référence dans le cadre de cette étude.Il a été mis en évidence que la configuration de base avec un sillage équilibré peut facilement être modifiée d’un point de vue aérodynamique en changeant l’état des roues (en rotation ou pas) et le type de pneumatique, en particulier sur l’essieu arrière. Cela provient d’un effet global et d’une sensibilité importante de l’équilibre du sillage aux changements de débit au soubassement. A contrario, lorsque le sillage du véhicule se trouve déséquilibré, il devient plus robuste par rapport à des perturbations de soubassement comme un changement d’état des roues ou une modification des pneumatiques. Si l’on supprime les quatre roues ou uniquement les deux roues avant, le débit de quantité de mouvement au soubassement est grandement augmenté. Par contre, si l’on supprime le diffuseur (changement important de la géométrie du véhicule), celui-ci s’en trouve nettement réduit. Dans ces deux configurations, le sillage est très fortement déséquilibré vers le sol et devient indépendant aux modifications apportées sur les roues.Il a également été mis en évidence un effet plus local du sillage des roues sur la portance et la traînée du véhicule.En effet, la zone de dépression dans le sillage des roues avant a un effet sur la portance alors que le sillage des roues arrière pilote en partie la pression au culot et donc la traînée. Il a ainsi été observé une augmentation importante de la traînée du véhicule lorsque le sillage des roues arrière, non fermé, venait en interaction directe avec le sillage du véhicule
The thesis aims to provide a better understanding of the wheel-vehicle interaction, via experimental investigations on a 2/5-th scale vehicle with an underbody diffuser and 2/5-th scale wheels equipped with Michelin tires. The vehicle geometry, based on ASMO model, was modified prior to the PhD work, in order to achieve a reasonable front wheel yaw angle, and a realistic wake balance with four rotating wheels. It is the baseline configuration in the scope of this work.The findings demonstrate that the well-balanced wake of the baseline configuration can be easily modified by different wheel states or tire modifications, especially at the rear axle. This results from a global effect of the underbody momentum modifications, i.e. a high wake sensitivity to the underbody flow. On the contrary, when the vehicle mean wake develops into a non-balanced topology, it is more robust towards underbody perturbations such as different wheel states or tire modifications. By eliminating four wheels or front wheels, the underbody momentum flux is vastly increased; by eliminating the underbody diffuser, which is a vehicle geometry modification, the underbody momentum flux is significantly reduced. In these two circumstances, one can observea robust downwash from the roof, independent of the wheel states or tire modifications. Besides, there is a more local effect of the wheels near wakes on the aerodynamic lift and drag of the vehicle. Low pressure regions in the underbody downstream the front wheels have an effect on vehicle lift. The rear wheels impose pressure conditions on the vehicle base, influencing the vehicle drag. Particularly, the merging of nonclosed mean wakes of the rear wheels with the vehicle wake can give rise to strong penalty in vehicle drag

This diploma thesis deals with constructional design and a calculation of one-girder bridge crane with the requested primary parametres: lifting capacity 10 000 kg, span 12 000 mm, wheel base 2 500 mm, travel height 7 000 mm. In diploma thesis, there is executed analysis of constructional designs of box girders, drawn up technical report with the analysis of the choice of the construction with important technical and physical calculations. Calculations were executed according to valid Czech state norms and literature. Drawing documentation is enclosed to this thesis.

The goal of following master thesis is to design variety of configuration and retraction options of VUT200 TwinCobra landing gear. For each option are a wheel base and a gauge set up by possibility of main landing gear retraction. Next, CS 23 demands and stress analysis are followed. There is a view of twin engine aircraft landing gear disclosed as well.

In a near future, it is imminent that passenger vehicles will soon be introduced with a new revolutionary brake by wire system which replaces all the mechanical linkages and the conventional hydraulic brake systems with complete 'dry' electrical components. One of the many potential benefits of a brake by wire system is the increased brake dynamic performances due to a more accurate and continuous operation of the EMB actuators which leads to the increased amount of possibilities for control in antilock brake system. The main focus of this thesis is on the application of a model predictive control (MPC) method to devise an antilock brake control system for a brake by wire vehicle. Unlike the traditional ABS control algorithms which are based on a trial and error method, the MPC based ABS algorithm aims to utilizes the behaviour of the model to optimize the wheel slip dynamics subject to system constraints. The final implementation of the wheel slip controller emb races decentralized control architecture to independently control the brake torque at each four wheel. Performance of the wheel slip controller is validated through Software-in-the-Loop and Hardware-in-the-Loop simulation. In order to support the high demands of the computational power and the real time constraints of the Hardware-in-the-Loop simulation, a novel multi processor real-time simulation system is developed using the reflective memory network and the off-the-shelf hardware components.

This thesis aimed to develop deformable a virtual terrain which a vehicle can move in and interact with in a realistic manner. The theory used to calculate how the terrain influences the vehicle is based on terramechanics. The terrain is divided into two separate parts, one for visualization and one for physical collisions. Deformations of the graphical layer is calculated on the GPU using compute shader programming. The result of the thesis include a tech demo with a small landscape where an alternate terrain vehicle can deform the terrain as it moves around. The method for deforming the graphical layer is made in such a way so that the computational time does not increase as the size of the terrain does, making the method applicable to actual games.

Since its introduction by Shinbrot, numerous variations of parameter identification based on the Modulating Function Technique (MFT) have been developed. Recently researches have achieved to estimate also states through this method. In this thesis, the MFT is utilized for the estimation, of both parameters and states, that lead to observe the behaviour of the vertical suspension forces on a vehicle over time. In order to deal with the frequency disturbances present by perturbations as measurement noise and vibrations, the Fourier Modulating Function (FMF) as a kernel is proposed. Furthermore, this method is implemented with the concept of sensor fusion. The estimation that results after the implementation of an adaptive observer during the present work is going to show the robustness of the studied technique.
Seit der Einführung der Modulationsfunktionstechnik (MFT) durch Shinbrot wurden zahlreiche Methoden zur Identifikation von Parametern entwickelt. Die aktuelle Forschung hat inzwischen auch das Schätzen von Zustandsgrößen mit dieser Technik erreicht. In dieser Masterarbeit wird die MFT für die Zustands- und Parameterschätzung verwendet um das dynamische Verhalten der vertikalen Federung an einem Fahrzeug zu beobachten. Um mit Störungen durch Messrauschen und Vibrationen umzugehen wird die Fouriermodulationsfunktion (FMF) als Kern vorgeschlagen. Des Weiteren wird die Methode mit dem Konzept der Sensorfusion implementiert. Das Ergebnis ist eine robuste Schätzung, wie in der vorliegenden Arbeit gezeigt wird.
Tesis

The inherited rotation in a caster wheel allows movement in any direction, but pays at the expense of reaction torques. When implemented in a mobile robot, these forces have a negative impact in its performance. One approach is to restrict rotations on the spot by attaching a filter to the output of the motion planner. However, this formulation compromises the navigation’s completion in critical scenarios, such as parking, taking curves in narrow corridors or navigating at the presence of a high density of obstacles. Therefore, in this thesis we consider the influence of caster wheels in the motion planning stage, commonly presented as local planning. This work proposes a Model Predictive Control (MPC) based local planner that integrates the caster wheel physics into the motion planning stage. A caster wheel aware term is combined with a reference tracking based navigation, which leads to the formulation of the Caster Wheel Aware Local Planner (CWAWLP). Since this method requires knowing the caster wheel’s state and there is no sensor that provides this information, a caster wheel state observer is also formulated. In order to evaluate the impact of the caster wheel aware term, CWAWLP is compared to a Caster Wheel based Agnostic Local Planner (CWAGLP) and a Caster Wheel based Agnostic Planner Local Planner with Path Filter (CWPFLP). After running simulations for three case studies in a virtual framework, two experimental case studies are conducted in an intra-logistics robot. These are evaluated according to the navigation’s quality, motor torque usage and energy consumption. According to the patterns observed in the evaluation, CWAWLP covers a longer distance than CWAGLP wihout decreasing the navigation’s quality. At the same time, its motor torques are similar to the ones of CWPFLP. Therefore, CWAWLP is capable of considering caster wheel physics without sacrificing navigation capabilities. The formulated caster wheel aware term is compatible with any MPC based navigation algorithm and inherits the derivation of an observer capable of estimating caster wheel rotation angles and rolling speeds. Even if the caster wheel awareness has been implemented in a differential driven robot, this approach is also applicable to vehicles with an alternative drivetrain, such as car-like robots.
Den ärvda rotationen i ett hjul möjliggör rörelse i vilken riktning som helst, men fås på bekostnad av reaktionsmoment. När de implementeras i en mobil robot har dessa krafter en negativ inverkan på dess prestanda. Ett tillvägagångssätt är att begränsa rotationer på plats genom att applicera ett filter på rörelseplannerns utgång. Denna formulering komprometterar dock navigeringens slutförande i kritiska scenarier, såsom parkering, kurvor i smala korridorer eller navigering i närheten av höga hinder. Därför beaktar vi i denna avhandling påverkan av hjul på hjulplaneringen, som ofta presenteras som lokal planering. Detta arbete föreslår en Model Predictive Control (MPC) -baserad lokal planerare som integrerar svängbara länkhjuls fysik i rörelseplaneringsstadiet. En kugghjulmedveten term kombineras med en referensspårningsbaserad navigering, vilket leder till formuleringen av Caster Wheel Aware Local Planner (CWAWLP). Eftersom denna metod kräver kunskap om svängbara länkhjuls tillstånd och det inte finns någon sensor som ger denna information, formuleras också en hjulhjulstillståndsobservatör. För att utvärdera effekten av det medvetna begreppet svängbara änkhjul jämförs CWAWLP med en Caster Wheel-baserad Agnostic Local Planner (CWAGLP) och en Caster Wheel-baserad Agnostic Planner Local Planner with Path Filter (CWPFLP). Efter att ha kört simuleringar för tre fallstudier i ett virtuellt ramverk genomförs två experimentella fallstudier i en intra-logistikrobot. Dessa utvärderas enligt navigeringens kvalitet, vridmomentanvändning och energiförbrukning. Enligt de mönster som observerats i utvärderingen når CWAWLP ett längre avstånd än CWAGLP utan att sänka navigeringens kvalitet. Samtidigt liknar motorns vridmoment dem som CWPFLP. Därför kan CWAWLP ta hänsyn till svängbara länkhjuls fysik utan att offra navigationsfunktionerna. Den formulerade medhjulningsmedveten termen är kompatibel med vilken MPC-baserad navigationsalgoritm som helst och ärver härledningen av en observatör som kan uppskatta hjulets rotationsvinklar och rullningshastigheter. Även om hjulhjälpmedvetenheten har implementerats i en differentierad robot, är detta tillvägagångssätt också tillämpligt på fordon med ett alternativt drivsystem, såsom billiknande robotar.

The issue of low adhesion between the wheel and the rail has been a problem for the design and operation of the railway vehicles. The level of adhesion can be influenced by many different factors, such as contamination, climate, and vegetation, and it is extremely difficult to predict with certainty. Changes in the adhesion conditions can be rapid and short-lived, and values can differ from position to position along a route, depending on the type and degree of contamination. All these factors present a significant scientific challenge to effectively design a suitable technique to tackle this problem. This thesis presents the development of a unique, vehicle based technique for the real-time estimation of the contact conditions using multiple models to represent variations in the adhesion level and different contact conditions. The proposed solution exploits the fact that the dynamic behaviour of a railway vehicle is strongly affected by the nonlinearities and the variations in creep characteristics. The purpose of the proposed scheme is to interpret these variations in the dynamic response of the wheelset, developing useful contact condition information. The proposed system involves the use of a number of carefully selected mathematical models (or estimators) of a rail vehicle to mimic train dynamic behaviours in response to different track conditions. Each of the estimators is tuned to match one particular track condition to give the best results at the specific design point. Increased estimation errors are expected if the contact condition is not at or near the chosen operating point. The level of matches/mismatches is reflected in the estimation errors (or residuals) of the models concerned when compared with the real vehicle (through the measurement output of vehicle mounted inertial sensors). The output residuals from all the models are then assessed using an artificial intelligence decision-making approach to determine which of the models provides a best match to the present operating condition and, thus, provide real-time information about track conditions.

In recent years many companies have investigated the use of hybrid technology due to the potential of increasing the driveline’s efficiency and thus reducing fuel consumption. Previous studies show that hydraulic hybrid technology can be favourable to use in construction machinery such as wheel loaders, which often operate in repetitive drive cycles and have high transient power demands. Parallel as well as Series hybrid configurations are both found suitable for wheel loader applications as the hybrid configurations can decrease the dependency on the torque converter. This project has investigated a novel hydraulic hybrid concept which utilizes the wheel loaders auxiliary pump as a supplement to enable both Series and Parallel hybrid operation. Impact of accumulator sizes has also been investigated, for which smaller accumulator sizes resembles a hydrostatic transmission. The hybrid concept has been evaluated by developing a wheel loader simulation model and a control system based on a rule-based energy management strategy. Simulation results indicate improved energy efficiency of up to 18.80 % for the Combined hybrid. Moreover, the accumulator sizes prove to have less impact on the energy efficiency. A hybrid system with decreased accumulator sizes shows improved energy efficiency of up to 16.40 %.

O uso de tintas à base de solventes tem acarretado problemas ambientais, gerando a necessidade de pesquisas para o desenvolvimento de materiais com baixo teor de compostos orgânicos voláteis (VOC) para redução do impacto ao meio ambiente. Os efeitos do VOC ao meio ambiente motivaram este estudo, que tem como objetivos desenvolver uma nova tinta de base aquosa para a aplicação na fabricação de volantes automotivos. O presente trabalho tem como objetivo estudar o desempenho por meio de medição de camada de tinta, resistência aos reagentes químicos, combustibilidade e resistência ao desgaste da pintura obtida com tintas baseadas em 1) solventes orgânicos e 2) água, aplicadas em volantes automotivos constituídos de poliuretano (PU). Os resultados demonstram que a pintura à base de água possui uma espessura de camada maior e menor velocidade de combustão em relação à pintura à base de solventes orgânicos, porém apresenta um menor desempenho no ensaio de resistência à abrasão e aos reagentes químicos em relação à tinta à base de solventes orgânicos.
The use of solvent-based paints has caused environmental problems, creating the need for research to develop materials with low volatile organic compound (VOC) to reduce the environmental impact. The effect of volatile organic compound (VOC) to the environment motivated this study, which aims to develop a new water-based paint for application in the manufacture of automotive steering wheels. The present work aim to study the performance by measuring the layer thickness, resistance to chemical reagents, combustibility and wear resistance obtained with paints based on 1) organic solvents and 2) water, applied in automotive steering wheels made of polyurethane (PU). The results has showed that water-based paint has a layer thickness greater and lower burning rate than solvent-based paint, but it has a lower performance in the test for resistance to abrasion and resistance to chemical reagents in relation to organic solvent-based paint.

Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009.
Committee Chair: Howard, Ayanna; Committee Member: Egerstedt, Magnus; Committee Member: Vela, Patricio. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Two new coordination polymers, DUT-82 and DUT-83 (DUT – Dresden University of Technology), were synthesized by a solvothermal reaction in methanol of rhodium(II) acetate and the tricarboxylic acid H₃btc (btc – benzene-1,3,5-tricarboxylate) or H₃btb (btb – benzene-1,3,5-tribenzoate), respectively. After drying using supercritical carbon dioxide, aerogels with specific surface areas of up to 1150 m² gˉ¹ and pore volumes of up to 2.26 cm³ gˉ¹ were obtained. Although there is no long range order in the materials, the presence of rhodium paddle-wheel units and thus a local order was proven by X-ray absorption spectroscopy measurements. DUT-82 shows good performance in the adsorption of hydrogen and a high affinity for carbon monoxide, which is rarely observed for metal–organic frameworks. Catalytic investigations demonstrate the activity of DUT-82 in the heterogeneous hydrogenation of styrene as a model system. DUT-82 can be recycled for at least ten cycles underlining the stability during the course of reaction.

Ett av flera huvudsyften med ett gränssnitt mellan hjärna och datorer är att förbättralivskvaliteten för förlamade personer. I tidigare studier har betydande ansträngningar gjorts föratt känna igen en användares avsikter. Dock finns inga tidigare studier som visar varför detta ärviktigt. De system som idag ligger i framkant gällande gränssnittet mellan hjärna och dator hardessvärre låg bandbredd vilket leder till en hög kognitiv belastning på användaren. Ett gränssnittmellan hjärna och dator som är designat med dynamisk anpassning kan minska ansträngningensom krävs av användaren för att använda systemet samt ge denna en förkroppsligande känsla.Utgående för detta försöker denna rapport att utveckla ett intelligent system för gränssnittetmellan hjärna och användare. Detta system baseras på lärandet av en användares beteende samtatt förutspå användarens intention när det kommer till att navigera en semiautonom robot. Vidarehar arbete lagts på att modellera en användare samt att bygga en robot för att träna denutvecklade algoritmen. Simulerade tester av den utvecklade algoritmen bekräftar möjligheternaatt använda ett sådant användare anpassat system för interaktionen mellan hjärna och dator.Även med en adaptiv gränssnitt mellan hjärna och dator så är systemet utsatt för fel på grund avfelaktig klassificering av användarens avsikt. Detta fel kan leda till felaktigt beteende hos enrobot eller felaktig förflyttning av en rullstol för en funktionshindrad person. Flera fysiologiskastudier har visat att fel-relaterade potentialer framkallas i hjärnan när ett fel begås av ett systemsom agerar som gränssnitt mellan människa och maskin. Erkännande av fel-relaterade potentialeri de inspelade elektroencefalografi data kan utnyttjas för att förhindra felfortplantning tillgenomförande och därmed fungera som en kontrollmekanism för att känna igen användarensintention. Således i den sista delen fokuserar denna uppsats på att utveckla en klassificerare fördetektering av fel-relaterade potentialer genom användning av Support Vector Machine ochresultatet visar jämförbar klassificerings prestanda för Support Vector Machine som för de bästaGauss klassificerare.
Among several, one of the main goals of Brain-computer interface (BCI) system is to improvethe quality of life for paralyzed persons. While significant effort has been made to recognize userintention, the necessity of predicting user intention in the context of BCI for navigational tasks todesign a dynamic interface, has not been addressed yet. State-of-the-art BCI system has lowbandwidth because of which the user is subjected to much cognitive or interaction load. Howevera BCI system designed with dynamic customization feature to adapt as per individual user,would indeed reduce the interaction load and provide embodiment feeling to the user. Thereforethis thesis attempts to develop an intelligent BCI system based on reinforcement learningapproach to learn the user behaviour and predict the intentions in the context of a semiautonomousrobotic navigational task.In addition, an effort has also been made towards modeling a user or to build an agent, in orderto train the developed algorithm. Simulated testing of the developed algorithm confirms thepotential of using such a user adapted brain-computer interface system.Even with an adaptive brain-computer interface, the system is prone to errors due tomisclassification of the user's intention. Propagation of this classification error could lead towrong execution of a robotic avatar or movement of a wheel-chair in use by a paralyzed person.Several physiological studies have shown that error-related potentials are elicited in the brainwhen an error is committed by the BCI system. Recognition of error-related potentials in theElectroencephalography recorded data could be exploited to prevent error propagation tillexecution and hence act as a verification mechanism for the classifier devoted for recognizinguser intention in the context of BCIs. Thus in the last part, this thesis focuses on developing aclassifier for detection of error-related potentials using Support Vector Machine and the resultshows comparable classification performance of Support Vector Machine to that of state-of-theartclassifiers such as Gaussian classifier and Bayesian filter method.

Defected wheel are one the major reasons endangered state of railroad vehicles safety statue, due to vehicle derailment and worsen the quality of freight and passenger transportation. Therefore, timely defect detection for monitoring and detecting the state of defects is highly critical. This thesis presents a passive non-contact acoustic structural health monitoring approach using ultrasonic acoustic emissions (UAE) to detect certain defects on different structures, as well as, classifying the type of the defect on them. The acoustic emission signals used in this study are in the ultrasonic range (18-120 kHz), which is significantly higher than the majority of the research in this area thus far. For the proposed method, an impulse excitation, such as a hammer strike, is applied to the structure. In addition, ultrasound techniques have higher sensitivity to both surface and subsurface defects, which make the defect detection more accurate. Three structures considered for this study are: 1) a longitudinal beam, 2) a lifting weight, 3) an actual rail-wheel. A longitudinal beam was used at the first step for a better understanding of physics of the ultrasound propagation from the defect, as well, develop a method for extracting the signature response of the defect. Besides, the inherent directionality of the ultrasound microphone increases the signal to noise ratio (SNR) and could be useful in the noisy areas. Next, by considering the ultimate goal of the project, lifting weight was chosen, due to its similarity to the ultimate goal of this project that is a rail-wheel. A detection method and metric were developed by using the lifting weight and two type of synthetic defects were classified on this structure. Also, by using same extracted features, the same types of defects were detected and classified on an actual rail-wheel.
Master of Science

Grinding is a complex material removal process with a large number of parameters influencing each other. In the process, the grinding wheel surface contacts the workpiece at high speed and under high pressure. The complexity of the process lies in the multiple microscopic interaction modes in the wheel-workpiece contact zone, including cutting, plowing, sliding, chip/workpiece friction, chip/bond friction, and bond/workpiece friction. Any subtle changes of the microscopic modes could result in a dramatic variation in the process. To capture the minute microscopic changes in the process and acquire better understanding of the mechanism, a physics-based model is necessary to quantify the microscopic interactions, through which the process output can be correlated with the input parameters. In the dissertation, the grinding process is regarded as an integration of all microscopic interactions, and a methodology is established for the physics based modeling. To determine the engagement condition for all micro-modes quantitatively, a virtual grinding wheel model is developed based on wheel fabrication procedure analysis and a kinematics simulation is conducted according to the operational parameters of the grinding process. A Finite Element Analysis (FEA) is carried out to study the single grain cutting under different conditions to characterize and quantify the grain-workpiece interface. Given the engagement condition on each individual grain with the workpiece from the physics-based simulation, the force, chip generation, and material plastic flow can be determined through the simulation results. Therefore, the microscopic output on each discrete point in the wheel-workpiece contact zone can be derived, and the grinding process technical output is the integrated product of all microscopic interaction output. From the perspective of process prediction and optimization, the simulation can provide the output value including the tangential force and surface texture. In terms of the microscopic analysis for mechanism study, the simulation is able to estimate the number of cutting and plowing grains, cutting and plowing force, probability of loading occurrence, which can be used as evidence for process diagnosis and improvement. A series of experiments are carried out to verify the simulation results. The simulation results are consistent with the experimental results in terms of the tangential force and surface roughness Ra for dry grinding of hardened D2 steel. The methodology enables the description of the 'inside story' in grinding processes from a microscopic point of view, which also helps explain and predict the time dependent behavior in grinding. Furthermore, the process model can be used for grinding force (or power) estimation for multiple-stage grinding cycles which includes rough, semi-finish, finish, and spark out. Therefore, the grinding process design can be carried out proactively while eliminating 'trial and error'. In addition, the grinding wheel model itself can be used to guide the recipe development and optimization of grinding wheels. While the single grain micro-cutting model can be used to study the mechanism of single grit cutting under various complex conditions, it can also be used to derive the optimal parameters for specific grains or process conditions.

Older adults are living longer than ever before. By 2060, the U.S. population aged 65 or older is projected to reach 98 million. As adults age, the prevalence of chronic diseases and disabilities increases. The need for Meals on Wheels (MOW) services is growing alongside the aging population. Yet, little is known about the geographic variation of services. Little is documented about the organizational capacity of MOW organizations in terms of geography. The current policies supporting home-and community-based services, including MOW, may be insufficient to support all older adults in all types of communities. An analysis of the More Than a Meal® Comprehensive Network Study was conducted to determine geographic variation in services delivered through MOW programs and to document organizational capacity by geography. Chi-squared analyses were performed to identify relationships between twenty services offered through MOW organizations and categorial offerings within nutrition, in-home safety, socialization, and community connections categories. Spidergrams were created to document organizational capacity holistically and for three individual organizations for each of the geographic areas: Rural Only, Partial Rural, and Non-rural Service Areas. Using these findings, a policy analysis was conducted to determine policy recommendations to inclusively support rural older adults. Older adults living in rural areas access the full complement of services provided by MOW programs differently than do their non-rural counterparts. Specifically, a statistically significant relationship was found between the stratified component of in-home safety for rural, partial rural and non-rural service areas. When evaluated on the individual service offering level, statistically significant relationships between rurality and congregate meals, nutrition education, nutrition assessment, coordination of USDA food assistance programs, and telephone reassurance were seen. Spidergram documentation of capacity created visual representations of geographic similarities and differences. The policy analysis produced three potentially viable policy additions for the Older Americans Act around a provision for innovation programs, a report on in-home safety, and business acumen provisions. This work lays the foundation for further analysis of existing data with a lens of geographic specificity, as well as articulates the importance of looking at organizational capacity as a part of policy recommendations for understanding rural community-based organizations.

During the last 10 years solar cooling systems attracted more and more interest not only in the research area but also on a private and commercial level. Several demonstration plants have been installed in different European countries and first companies started to commercialise also small scale absorption cooling machines. However, not all of the installed systems operate efficiently and some are, from the primary energy point of view, even worse than conventional systems with a compression chiller. The main reason for this is a poor system design combined with suboptimal control. Often several non optimised components, each separately controlled, are put together to form a ‘cooling system’. To overcome these drawbacks several attempts are made within IEA task 38 (International Energy Agency Solar Heating and Cooling Programme) to improve the system design through optimised design guidelines which are supported by simulation based design tools. Furthermore, guidelines for an optimised control of different systems are developed. In parallel several companies like the SolarNext AG in Rimsting, Germany started the development of solar cooling kits with optimised components and optimised system controllers. To support this process the following contributions are made within the present work: - For the design and dimensioning of solar driven absorption cooling systems a detailed and structured simulation based analysis highlights the main influencing factors on the required solar system size to reach a defined solar fraction on the overall heating energy demand of the chiller. These results offer useful guidelines for an energy and cost efficient system design. - Detailed system simulations of an installed solar cooling system focus on the influence of the system configuration, control strategy and system component control on the overall primary energy efficiency. From the results found a detailed set of clear recommendations for highly energy efficient system configurations and control of solar driven absorption cooling systems is provided. - For optimised control of open desiccant evaporative cooling systems (DEC) an innovative model based system controller is developed and presented. This controller consists of an electricity optimised sequence controller which is assisted by a primary energy optimisation tool. The optimisation tool is based on simplified simulation models and is intended to be operated as an online tool which evaluates continuously the optimum operation mode of the DEC system to ensure high primary energy efficiency of the system. Tests of the controller in the simulation environment showed that compared to a system with energy optimised standard control the innovative model based system controller can further improve the primary energy efficiency by 19 %.

The current state-of-the-art tyre models tend to be demanding in parameterisation terms, typically requiring extensive and expensive testing, and computational power. Consequently, an alternative parameterisation approach, which also allows for the separation of model fidelity from computational demand, is essential. Based on the above, a tyre model is introduced in this work. Tyre motion is separated into two components, the first being the non-linear global motion of the tyre as a rigid body and the second being the linear local deformation of each node. The resulting system of differential equations of motion consists of a reduced number of equations, depending on the number of rigid and elastic modes considered rather than the degrees of freedom. These equations are populated by the eigenvectors and the eigenvalues of the elastic tyre modes, the eigenvectors corresponding to the rigid tyre modes and the inertia properties of the tyre. The contact sub-model consists of bristles attached to each belt node. Shear forces generated in the contact area are calculated by a distributed LuGre friction model while vertical tread dynamics are obtained by the vertical motion of the contact nodes and the corresponding bristle stiffness and damping characteristics. To populate the abovementioned system of differential equations, the modal properties of the rigid and the elastic belt modes are required. In the context of the present work, rigid belt modes are calculated analytically, while in-plane and out-of-plane elastic belt modes are identified experimentally by performing modal testing on the physical tyre. To this end, the eigenvalue of any particular mode is obtained by fitting a rational fraction polynomial expression to frequency response data surrounding that mode. The eigenvector calculation requires a different approach as typically modes located in the vicinity of the examined mode have an effect on the apparent residue. Consequently, an alternative method has been developed which takes into account the out-of-band modes leading to identified residues representing only the modes of interest. The validation of the proposed modelling approach is performed by comparing simulation results to experimental data and trends found in the literature. In terms of vertical stiffness, correlation with experimental data is achieved for a limited vertical load range, due to the nature of the identified modal properties. Moreover, the tyre model response to transient lateral slip is investigated for a range of longitudinal speeds and vertical loads, and the resulting relaxation length trends are compared with the relevant literature.

It is generally known that stability of vehicles under certain driving conditions may be improved by forcing the wheels to turn at the same speed and angle regardless of the available traction under individual wheels. For conventional all-terrain vehicles or sport-utility vehicles, this function can be achieved by locking the mechanical differential system. In this thesis, we propose an innovative approach for locking the electrical differential system (EDS) of electric vehicles (EV) with independent brushless DC (BLDC) machine-based wheel drives. The proposed method locks the active wheels of the vehicle as if they were operating on a common “virtual” shaft. The locking algorithm is implemented by processing the Hall sensor signals of the considered motors and driving them with a single set of “averaged” Hall signals, thereby operating the motors at the same speed and angle. A detailed switch-level model of EDS embedded with the proposed Sync-Lock Control (SLC) along with the BLDC propulsion motors has been developed and compared against measurements for the considered BLDC propulsion motors. The proposed technique is shown to achieve better results compared to a conventional speed control loop as the considered motors are locked directly through the corresponding magnetic fields. An efficient realization of the proposed controller is presented that makes it possible to be potentially programmed inside existing motor controllers or implemented in a stand-alone microcontroller which can be packaged into a dongle circuit. The proposed SLC is implemented digitally using a programmable integrated circuit microcontroller. First, the Hall signals undergo a layer of filtering to mitigate the errors that are common due to Hall sensor misalignment in low-cost BLDC motors. Then, the locking algorithm is implemented by averaging the filtered Hall sensor signals. The SLC prototype is implemented in form of a standalone dongle-circuit that can be easily placed between the original Hall-sensors and the BLDC motor driver. Operation of typical industrial BLDC motors with the proposed controller is shown to outperform conventional controllers and lock both speed and angle of the motors.

An investigation of the electronic structure of some transition metal clusters comprising anti-ferromagnetically coupled, heterometallic arrays of eight metal ions that are wheel-shaped, is reported. The compounds were synthesized and provided by Dr. Grigore Timco of The University of Manchester and are formulated by their metal content as Cr7M, where M = a divalent 3d metal. Two families of wheels are the subject of this research, defined ‘green’ and ‘purple’ from their physical appearance. Within each family, the compounds are all isostructural. From simulation using a single Hamiltonian for Cr7M-purple compounds, where M = Zn, Mn, or Ni, it is shown that with only two exchange parameters, one JCr-Cr and one JCr-M, data from bulk magnetization, neutron scattering, Electron Paramagnetic Resonance (EPR) spectroscopy at multiple frequencies and specific heat measurements can be modelled and that there is transferability of parameters. Preliminary attempts to measure electron spin relaxation times for two of the purple wheels have shown values of T1 and T2 that are comparable with those of the more extensively studied green wheels and hence further studies in this area are warranted. Variable temperature Q- and W-band EPR spectra for a series of nine heterodimers comprising one green and one purple wheel, M=Zn, Mn or Ni in each case, are reported. For Cr7Zn-purple there is no magnetic exchange detected, whereas weak and quantifiable exchange is required to interpret the spectra from the other six dimers. EPR studies of three trimers of the form purple-green-purple are reported and the presence of magnetic exchange is identified by comparison with the spectra of the component single and double wheel compounds, although this is not quantified because of the numerical size of the simulations that are required. The process of comparing simulated to experimental spectra is a complex problem and one which is central to the work reported in this thesis. The problem of fitting has been investigated and two novel solutions, one based upon pixel mapping and the other based on wavelet transformation are proposed.

Two trigonal tritopic ligands with different conformational degree of freedom: conformationally labile H3tcbpa (tris((4-carboxyl)phenylduryl)amine) and conformationally obstructed H3hmbqa (4,4′,4′′-(4,4,8,8,12,12-hexamethyl-8,12-dihydro-4H-benzo[9,1]quino-lizino[3,4,5,6,7-defg]acridine-2,6,10-triyl)tribenzoic acid) are assembled with square-planar paddle-wheel nodes with the aim of selective engineering of the frameworks with tbo and pto underlying net topologies. In the case of H3tcbpa, both topological types were obtained forming non-interpenetrated MOFs namely DUT-63 (tbo) and DUT-64 (pto). Whereas synthesis of DUT-63 proceeds under typical conditions, formation of DUT-64 requires an additional topology directing reagent (topological modifier). Solvothermal treatment of the conformationally hindered H3hmbqa ligand with the Cu-salt results exclusively in DUT-77 material, based on the single pto net. The possibility to insert the salen based metallated pillar ligand into networks with pto topology post-synthetically results in DUT-78 and DUT-79 materials (both ith-d) and opens new horizons for post-synthetic insertion of catalytically active metals within the above-mentioned topological type of frameworks.

Two trigonal tritopic ligands with different conformational degree of freedom: conformationally labile H3tcbpa (tris((4-carboxyl)phenylduryl)amine) and conformationally obstructed H3hmbqa (4,4′,4′′-(4,4,8,8,12,12-hexamethyl-8,12-dihydro-4H-benzo[9,1]quino-lizino[3,4,5,6,7-defg]acridine-2,6,10-triyl)tribenzoic acid) are assembled with square-planar paddle-wheel nodes with the aim of selective engineering of the frameworks with tbo and pto underlying net topologies. In the case of H3tcbpa, both topological types were obtained forming non-interpenetrated MOFs namely DUT-63 (tbo) and DUT-64 (pto). Whereas synthesis of DUT-63 proceeds under typical conditions, formation of DUT-64 requires an additional topology directing reagent (topological modifier). Solvothermal treatment of the conformationally hindered H3hmbqa ligand with the Cu-salt results exclusively in DUT-77 material, based on the single pto net. The possibility to insert the salen based metallated pillar ligand into networks with pto topology post-synthetically results in DUT-78 and DUT-79 materials (both ith-d) and opens new horizons for post-synthetic insertion of catalytically active metals within the above-mentioned topological type of frameworks.

Early detection of rail defects is necessary for preventing derailments and costly damage to the train and railway infrastructure. A rail surface flaw can quickly propagate from a small fracture to a broken rail after only a few train cars have passed over it. Rail defect detection is typically performed by using an instrumented car or a separate railway monitoring vehicle. Rail surface irregularities can be measured using accelerometers mounted to the bogie side frames or wheel axles. Typical signal processing algorithms for detecting defects within a vertical acceleration signal use a simple thresholding routine that considers only the amplitude of the signal. As a result, rail surface defects that produce low amplitude acceleration signatures may not be detected, and special track components that produce high amplitude acceleration signatures may be flagged as defects. The focus of this research is to develop an intelligent signal processing algorithm capable of detecting and classifying various rail surface irregularities, including defects and special track components. Three algorithms are proposed and validated using data collected from an instrumented freight car. For the first two algorithms, one uses a windowed Fourier Transform while the other uses the Wavelet Transform for feature extraction. Both of these algorithms use an artificial neural network for feature classification. The third algorithm uses the Wavelet Transform to perform a regularity analysis on the signal. The algorithms are validated with the collected data and shown to out-perform the threshold-based algorithm for the same data set. Proper training of the defect detection algorithm requires a large data set consisting of operating conditions and physical parameters. To generate this training data, a dynamic wheel-rail interaction model was developed that relates defect geometry to the side frame vertical acceleration signature. The model was generated by using combined systems dynamic modeling, and the system was solved with a developed combined lumped and distributed parameter system numerical approximation. The broken rail model was validated with real data collected from an instrumented freight car. The model was then used to train and validate the defect detection methodologies for various train and rail physical parameters and operating conditions.
Ph. D.

The main objective of the present thesis focuses on the integration of the in-wheel electric motors into the conception and control of road vehicles. The present thesis is the subject of the grant 186-654 (2010-2013) between the Laboratory of Signals and Systems (L2S-CNRS) and the French Institute of Petrol and New Energies (IFPEN). The thesis work has originally started from a vehicular electrification project, equipped with in-wheel electric motors at the rear axle, to obtain a full electric urban use and a standard extra-urban use with energy recovery at the rear axle in braking phases. The standard internal combustion engines have the disadvantage that complex estimation techniques are necessary to compute the instantaneous engine torque. At the same time, the actuators that control the braking system have some delays due to the hydraulic and mechanical circuits. These aspects represent the primary motivation for the introduction and study of the integration of the electric motor as unique propelling source for the vehicle. The advantages brought by the use of the electric motor are revealed and new techniques of control are set up to maximize its novelty. Control laws are constructed starting from the key feature of the electric motor, which is the fact that the torque transmitted at the wheel can be measured, depending on the current that passes through the motor. Another important feature of the electric motor is its response time, the independent control, as well as the fact that it can produce negative torques, in generator mode, to help decelerate the vehicle and store energy at the same time. Therefore, the novelty of the present work is that the in-wheel electric motor is considered to be the only control actuator signal in acceleration and deceleration phases, simplifying the architecture of the design of the vehicle and of the control laws. The control laws are focused on simplicity and rapidity in order to generate the torques which are transmitted at the wheels. To compute the adequate torques, estimation strategies are set up to produce reliable maximum friction estimation. Function of this maximum adherence available at the contact between the road and the tires, an adequate torque will be computed in order to achieve a stable wheel behavior in acceleration as well as in deceleration phases. The critical issue that was studied in this work was the non-linearity of the tire-road interaction characteristics and its complexity to estimate when it varies. The estimation strategy will have to detect all changes in the road-surface adherence and the computed control law should maintain the stability of the wheel even when the maximum friction changes. Perturbations and noise are also treated in order to test the robustness of the proposed estimation and control approaches.

The following work focuses on the kinematic and dynamic study of a four-wheeled robot, which is equipped with omnidirectional Mecanum wheels. The main objective of the thesis is to obtain a mathematical model from which both the kinematics and kinetics of the robot can be analyzed. Furthermore, the study presents a methodology to optimize the torques (and subsequent associated voltages) provided by each of the motors on the robot for a given trajectory. A system in which a non-powered trailer pulled by the robot is also analyzed at a kinematic level. In this stage, four different cases are considered. The construction of the trailer is also described on this work. In the first chapter, the global state of the art on analysis and control of omnidirectional robots (with focus on robots with Mecanum wheels) is presented. In the second chapter, the physical considerations for the general movement of the robot are analyzed, in order to derive the kinematic constrain equations of the locomotion system. The differential equation of motion is then derived using Lagrange-equations with multipliers. This chapter presents as well the kinematic analysis for a robot-trailer system. The third chapter describes the general process on the design of the trailer, including the rejected ideas for its construction. The fourth chapter focuses on verifying the final results of the design process, as well as tests to check the mobility of the system. Conclusions and future work are analyzed on the final part of the document, as well as the references and the acknowledgments to all the people involved in the project.
Tesis

The construction equipment industry is developing at a fast pace, increasing the expectation on the next-generation machines. Wheel loaders and backhoe loaders are part of this evolution and all subsystems in those machines need to be developed to meet the high demands in energy eciency and productivity. One of the most important parts of the wheel loader is the loading unit. This is traditionally designed using highly experienced engineers and CAD software. To simplify the early stages of this process was an optimization tool developed to generate a design outlay. The optimization will minimize the mass of the linkage since unnecessary weight will lower the eciency. The minimum can be found by moving the joints and adjusting the shape of the device. The optimization will also include constraints to assure the correct performance of the linkage. Since there are a high number of design variables, a gradient-based optimization method was used. A finite element solver was also implemented to calculate the forces and stresses in the linkage. The linkages studied in this report are one from a typical wheel loader and one from a backhoe loader. Since these machines are extremely versatile, and used formany diferent tasks, two sets of constraints are compiled. One of the constraint sets yields a linkage suitable for machines only equipped with bucket, while the other results in an all-round linkage suitable for most tools and applications. The optimized linkages are compared to existing devices. The results show that there are some improvements possible and that the software could be used to help designers. However, the optimization problem is hard to solve due to non-smooth constraints functions and numerical instabilities. This issue could be overcome by diferent means, like using automatic diferentiation, a non-gradient based optimization method, decreasing the number of constraints or decreasing the number of design variables.
Utvecklingen av anlaggningsmaskiner sker i snabb takt och detta ökar förväntningarna på framtidens maskiner. En stor andel av alla anläggningsmaskiner är hjullastare och traktorgrävare och alla delsystem på dessa maskiner måste följa med i utvecklingen. En av de viktigaste delarna pa en hjullastare ar lastaggregatet. Det designas traditionellt med hjälp av CAD mjukvara och mycket erfarna konstruktörer. För att underlätta denna process har en optimeringsrutin utvecklats, som generarar ett designförslag. Optimeringen minskar länkagets massa genom att fytta lagringspositioner och ändra delarnas dimensioner. Detta ökar efektiviteten hos maskinen eftersom den slipper köra runt på onödig vikt. Optimeringen innehåller även villkor för att säkerställa god prestanda hos det optimerade aggregatet. Eftersom det ingår väldigt många designvariabler i optimeringen används en gradientbaserad metod. En finita element approximation används for att beräkna krafter och spänningar i länkaget. De länkage som undersöks i detta projekt är ett typsikt hjullastaraggregat och ett typiskt traktorgrävaraggregat. Eftersom dessa maskiner ar väldigt mångsidiga sammanställdes två olika uppsättningar av villkor. Den ena uppsättningen används för att optimera ett aggregat som endast ska användas med skopa, medan den andra uppsättningen används för att ta fram ett mer mångsidigt aggregat avsätt for att kunna klara av de flesta situationer och verktyg. De optimerade lastaggregaten är jämförda med produktionsaggregat och det visar sig att vissa förbättringar är möjliga. Slutsattsen är att optimeringsrutinen kan bli ett bra hjälpmedel for konstruktörer men att den behöver lite mer veriering. Villkorsfunktionen som optimeringen måste lösa är inte helt slät vilket är ett problem för en gradientbaserade metod och dessutom finns vissa numeriska instabiliteter. Dessa svårigheter kan undkommas pa olika sätt, t.ex. genom att använda automatisk derivering,byta optimeringsalgoritm, minska antalet villkor eller minska antalet variabler.

In many products a compromise between ground clearance and the required space to store the product has to be made. This problem attracted the attention of the authors of this thesis.The objective of this project is to develop a functioning solution to a foldable wheel. The solution should be applicable to several types of product groups. A limitation for this work has been made so that the work only covers solutions for lighter vehicles.The purpose is to drive this project forward, so that a solution can be found. Furthermore the purpose of the report is to clarify how the authors proceeded to design and construct the wheel according to a fixed specification. The authors of this project also wishes to develop their knowledge within the field of product development.Set-Based Concurrent Engineering (SBCE) has been used as the underlying method on which this work was based. The work started with a preliminary study. Relevant specifications was established using the results from the study. The specifications was given a rang by the use of pairwise weighting, then a QFD was made using said requirements.The wheel was divided into three different areas. Solutions was developed to problems within each area, independently of one another. The project underwent three concept stages and three screening stages. During the third screening a final concept was chosen for further development.Strength simulations was performed in Solid Works, by using the results from the simulations adjustments to the design could be made.The authors succeeded in developing a wheel capable of a volume reduction by 70 %. When the wheel is dimensioned to fit an ordinary bike it weighs about 2.5kg and can take a radial load of over 1 000N. The final concept is called Arcas and is made up of four sections of a specially developed flexible arc-solution. The arc-solution enables the wheels curved surfaces to be straightened out when the wheel is about be stored.The authors consider that they have developed the knowledge in product development and also improved their ability to handle loose defined projects. It should be possible to further reduce the volume up to levels around 80 %. A detailed FEM analysis of the components should be of use.
Hos många produkter måste en kompromiss göras mellan markfrigång och krävt förvaringsutrymme. Detta problem uppmärksammades av författarna till denna uppsats.Målet med detta projekt är att är att ta fram en fungerande hjullösning på ett hoppfällbart hjul. Lösningen ska gå att applicera inom olika produktgrupper, dock har arbetet begränsats till att endast omfatta lösningar till lättare fordon.Syftet är att driva projektet framåt så att en lösning på problemet hittas. Vidare är syftet med rapporten att redogöra för hur författarna gått tillväga för att designa och konstruera hjulet enligt satta kriterier. Författarna vill även fördjupa sina kunskaper inom produktutveckling.Set-Based Concurrent Engineering (SBCE) har använts som övergripande metod i detta arbete. Arbetsprocessen började med en förstudie. Relevanta krav på produkten upprättades baserade på genomförd förstudie. Kraven viktades genom parvis viktning och en QFD upprättades med dessa krav. Hjulet delades upp i tre olika områden. Lösningar togs fram på problem inom de tre områdena oberoende av varandra. Projektet genomgick tre stycken konceptfaser och tre stycken sållningar. Vid den tredje sållningen valdes ett slutkoncept att arbeta vidare emot.Hållfasthetssimuleringar utfördes sedan i Solid Works, med hjälp av resultaten på dessa kunde justeringar av designen utföras.Författarna lyckades att ta fram ett hjul kapabelt av en volymminskning med 70 %. Då hjulet är dimensionerat för att passa en vanlig cykel väger det ca 2.5kg och klarar av en radiell last på över 1 000N. Det slutgiltiga konceptet heter Arcas och består av fyra sektioner av en speciellt utvecklad flexibel båglösning. Båglösningen tillåter hjulets krökta ytor att rätas ut när hjulet skall förvaras.Författarna anser sig ha fördjupat sina kunskaper inom produktutveckling och framförallt förbättrat förmågan att hantera projekt med lösa ramar. Det borde vara möjligt att öka graden av hoppfällning så att volymminskningen kommer upp i nivåer kring 80 %. En ingående FEM-analys på ingående komponenter skulle vara användbar.

[ES] El ruido de rodadura es un fenómeno producido debido a la interacción entre la rueda y el carril e inducido por las pequeñas irregularidades existentes en la superficie de ambos. Dichas irregularidades, conocidas como "rugosidad", provocan que se genere una vibración tanto en la rueda como el carril cuando el tren circula a una cierta velocidad, lo que consecuentemente lleva a la aparición de radiación acústica. Esto conforma una de las fuentes de molestias más relevantes y principal origen de la contaminación acústica producida por los trenes al circular por regiones urbanas densamente pobladas. Así, el objetivo de esta Tesis es el desarrollo de una metodología integral para la obtención de diseños de rueda viables mediante el uso de Algoritmos Genéticos (AG) con la finalidad de minimizar el ruido de rodadura asociado. Al desarrollar los mencionados algoritmos de optimización, el Método de Elementos Finitos (MEF) se combina con la parametrización geométrica de las diferentes tipologías de diseño de rueda analizadas, descritas en función de aquellos parámetros más relevantes para la presente investigación. Se hace uso de modelos linealizados en el dominio de la frecuencia, capaces de resolver la dinámica completa del sistema a partir de las correspondientes mallas de la sección transversal. La obtención de la potencia acústica radiada se lleva a cabo mediante el empleo de una formulación semi-analítica para el cálculo de la eficiencia acústica de la rueda y al uso de un Modelo de Fuentes Equivalentes (MFE) en el carril. El desarrollo teórico, además, es validado con el software comercial de referencia en el campo de investigación, TWINS, en el cual se basa. A lo largo de los procedimientos de optimización, se realiza un análisis de fatiga en cada diseño de rueda considerado con el fin de asegurar su viabilidad estructural, lo que actúa como una restricción de "pena de muerte" en el algoritmo. Además, se desarrolla un procedimiento de identificación modal que permite caracterizar los modos de vibración y clasificarlos según su número de diámetros y circunferencias nodales. Seguidamente, se exploran dos formulaciones diferentes de la función objetivo: una centrada en reducir directamente el ruido radiado, llamada LA;W -min; i otra centrada en disminuir el ruido de rodadura maximizando la media de las frecuencias naturales de los modos de vibración, conocida como NF-max. En la metodología LA;W -min, se minimiza la suma en energía del nivel de potencia acústica expresado en dB(A). Para el caso de NF-max, se desplazan las frecuencias naturales a regiones de frecuencia donde la amplitud de rugosidad es menor. Se consideran diversas aproximaciones: la inclusión de esquemas de perforación y la modificación de la forma de su sección transversal. Además, también se ha estudiado la influencia en el ruido de la variación de las propiedades geométricas del carril y viscoelásticas de la vía. Como resultado de esta Tesis se han conseguido diversos modelos más silenciosos de rueda ferroviaria, con reducciones en el ruido de rodadura de hasta 5 dB(A). Cuando se considera el sistema ferroviario completo,se siguen consiguiendo mejoras en la potencia acústica radiada con los diseños de rueda resultantes. Además, se analizan las correlaciones entre la maximización de las frecuencias naturales y la atenuación del nivel de potencia acústica, estableciendo NF-max como una metodología adecuada para los casos en que se priorice la eficiencia computacional. La sensibilidad del problema a los espacios de diseño seleccionados y la adecuación del uso de AG se estudian también con la obtención de Superficies de Respuesta. Adicionalmente, se han establecido relaciones entre la variación de los parámetros geométricos y la disminución en la radiación acústica asociada, así como se ha propuesto la reubicación de los modos de vibración a lo largo del espectro en frecuencia com
[CA] El soroll de rodament és un fenomen causat per la interacció entre la roda i el carril i induït per les xicotetes irregularitats presents a les seues superfícies. Aquestes irregularitats, conegudes amb el nom de "rugositat", provoquen que es genere una vibració tant a la roda com al carril en circular el tren a una certa velocitat, el que conseqüentment du a l'aparició de radiació acústica. Açò conforma una de les fonts de molèsties més rellevants i el principal origen de la contaminació acústica generada pels trens al seu pas per regions urbanes densament poblades. Així, l'objectiu d'aquesta Tesi és el desenvolupament d'una metodologia integral per a l'obtenció de dissenys de roda viables mitjançant l'ús d'Algoritmes Genètics (AG) amb la inalitat de minimitzar el soroll de rodament associat. Al desenvolupar els esmentats algoritmes d'optimització, el Mètode d'Elements Finits (MEF) es combina amb la parametrització geomètrica de les diferents tipologies de disseny de roda analitzades, descrites en funció d'aquells paràmetres més rellevants per a aquesta investigació. Es fa ús de models linealitzats en el domini de la freqüència, capaços de resoldre la dinàmica completa del sistema a partir les corresponents malles de secció transversal. La obtenció de la potència acústica radiada es du a terme mitjançant la utilització d'una formulació semi-analítica per al càlcul de l'eficiència acústica de la roda i l'ús d'un Model de Fonts Equivalents (MFE) amb el carril. El desenvolupament teòric s'ha validat amb el software comercial de referència al camp d'investigació, TWINS, en el qual es basa. Al llarg dels procediments d'optimització, es realitza una anàlisi de fatiga a cada disseny de roda considerat amb la finalitat d'assegurar la seua viabilitat estructural. S'ha desenvolupat un procediment d'identificació modal que permet caracteritzar els modes de vibració i classificar-los d'acord al seu número de diàmetres i circumferències nodals. També, s'exploren dos formulacions diferents de la funció objectiu: una centrada en reduir directament el soroll radiat, anomenada LA;W -min; i altra centrada en disminuir el soroll de rodament maximitzant la mitja de les freqüències naturals dels modes de vibració, coneguda com NF-max. D'aquesta manera, en la metodologia LA;W -min, es minimitza la suma en energia del nivell de potència acústica expressat en dB(A). Per al cas de NF-max, es desplacen les freqüències naturals a regions de freqüència on l'amplitud de rugositat és menor. Es consideren diverses aproximacions: la inclusió d'esquemes de perforació i la modificació de la forma de la seua secció transversal, establint el radi com un valor fixe en un cas i utilitzant-lo com un paràmetre d'optimització més en l'altre. A més a més, s'ha estudiat la influència en el soroll de la variació de les propietats geomètriques del carril i viscoelàstiques de la via. Com a resultat d'aquesta Tesi s'han aconseguit diversos models de roda ferroviària més silenciosos, amb reduccions en el soroll de rodament de fins a 5 dB(A). Quan es considera el sistema ferroviari complet amb tots els seus components, es segueixen aconseguint millores en la potencia acústica radiada amb els dissenys de roda resultants. A més a més, 'analitzen les correlacions entre la maximització de les freqüències naturals i l'atenuació del nivell de potencia acústica, establint NF-max com una metodologia adequada pels casos en que es prioritza l'eficiència computacional. La sensibilitat del problema als espais de disseny escollits i l'adequació de l'ús de AG s'estudia també mitjançant l'obtenció de Superfícies de Resposta (SRs) per als paràmetres geomètrics utilitzats. Addicionalment, s'han establert relacions entre la variació dels paràmetres geomètrics i la disminució en la radiació acústica associada, així com s'ha proposat la reubicació dels modes de vibració al voltant de
[EN] Rolling noise phenomenon is produced due to the wheel/track interaction and induced by the small unevenness present in their surfaces. Such unevenness, known as "roughness", causes that vibrations arise in both the wheel and track when the train passes by with a certain speed, that consequently leads to the appearance of acoustic radiation. This kind of noise is one of the most relevant sources of annoyance and the principal focus of the railway acoustic pollution produced by trains operating through highly populated urban regions. Thus, the main goal of the present Thesis is the development of a comprehensive methodology to achieve suitable railway wheel designs through the use of Genetic Algorithms (GAs) with the aim of minimizing the associated rolling noise. When developing the aforementioned optimization algorithms, the Finite Element Method (FEM) is combined with the geometric parametrization of the different wheel design typologies analysed, described as a function of those parameters most relevant for the current research. In order to describe the dynamic behaviour of each component involved in the wheel/track interaction, use is made of linearised models in the frequency domain capable of solving the whole coupled dynamic response from the corresponding cross-section meshes. Subsequent derivation of the radiated sound power from the dynamic information is carried out by applying a semi-analytical formulation that allows for the wheel acoustic efficiency computation, on one hand, and by making use of an Equivalent Sources Model (ESM) in the track, on the other hand. Besides, such theoretical development is validated with the reference commercial software in the field, TWINS, on which it is based. Throughout the optimization procedures, a fatigue analysis is performed on every wheel design considered to assure structural feasibility, that acts as a "death penalty" constraint in the algorithm. Furthermore, a modal identification procedure is developed, which allows to characterize modeshapes and to classify them according to their number of nodal diameters and circumferences. Then, two different formulations of the objective function are explored: one focused on directly reducing radiated noise, named LA;W-min; and another centred on decreasing rolling noise by maximizing the average natural frequency of the modeshapes, called NF-max. Hence, in the LA;W -min methodology, the sum in energy of the wheel Sound poWer Level (SWL) expressed in dB(A) is minimized. For the NF-max case, natural frequencies are shifted to frequency regions where the roughness amplitude content is lower. Different approaches are considered: the inclusion of perforation schemes in the wheel and the variation of its cross-sectional shape, setting the radius as a constant value in one case and using it as an optimization parameter in another. Moreover, the influence on the noise of changing the rail geometric and track viscoelastic properties is also studied. As a result of the present Thesis, several quieter models of railway wheels have been achieved, with rolling noise reductions of up to 5 dB(A). When the whole railway system with all the components is considered, improvements in the radiated sound power remain achieved with the resulting wheel designs. Besides, correlations between maximization of natural frequencies and SWL mitigation are analysed, establishing the NF-max as a suitable methodology for cases when computational efficiency is prioritized. The sensitivity of the problem to selected design domains and the suitability of the use of GAs are also studied with the obtention of Response Surfaces (RSs) for the geometric parameters used. Additionally, correlations are established between the variation of the geometric parameters and the decrease in the associated acoustic radiation, while the shifting of the modeshapes along the frequency domain is proposed as a physical mechanism responsible of the observed sound power decrease.
This thesis has been supported by the Agencia Estatal de Investigación and the European Regional Development Fund (projects TRA2013-45596-C2-1-R and TRA2017-84701-R).
Garcia Andrés, X. (2021). Development of innovative methodologies to reduce railway rolling noise through Genetic Algorithm-based shape optimization techniques [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/164194
TESIS

The roads in our society are in a state of constant degradation. The reasons for this are many, and therefore constructed to have a certain lifetime before being reconstructed. To minimize the cost of maintaining the important transport road network high quality prediction models are needed. This report presents new models for flexible pavement structures for initiation and propagation of fatigue cracks in the bound layers and rutting for the whole structure. The models are based on observations from the Swedish Long Term Pavement Performance (LTPP) database. The intention is to use them for planning maintenance as part of a pavement management system (PMS). A statistical approach is used for the modeling, where both cracking and rutting are related to traffic data, climate conditions, and the subgrade characteristics as well as the pavement structure.

QC 20130325

Deviations from the design track geometry are called track irregularities, which are a main excitation mechanism in the track–vehicle dynamic system, and very important to monitor and maintain to have trac on a line run safely and comfortably. Especially during vehicle acceptance testing, it is important that a new vehicle behaves close to design predictions and within limit values, thus it is important to be able to describe track irregularities in a consistent way. There are several methods which quantify the eects track irregularities have on a vehicle while running along the track. Most common is analyse standard deviations and percentiles and maximum values over sections with pre-defined length. However, these quantities do not correlate well with the vehicle dynamic response, e.g. two track sections with similar maxima and standard deviations can result in very dierent response of the vehicle. To improve the correlation between track irregularities and vehicle re- sponse measures, it is recommended by past research to use multiple regres- sion analysis to take e.g. vehicle speed and track curvature into account as well. Other methods range from derivatives of track irregularities, via trans- fer functions and vehicle filters to neural networks. Common for all these methods are that there is either still slight inconsistencies in the results or that they are tailored for certain vehicle types on specific lines. As a result, the preferred method to evaluate track irregularities is still to use standard deviations. In this thesis, data from three vehicles in two measurement campaigns is evaluated using a single degree of freedom model as inspiration to break down the path from track to vehicle into several steps. A weak link in these steps is identified, which shows significantly lower correlation coecients than the other steps. The weak link is the step from vertical track irregularity second spatial derivative to vertical axle box acceleration divided by the squared vehicle speed. A variable wavelength range Dx is introduced, as an alternative to the common D1 (3–25 m), D2 (25–70 m) and D3 (70–150 m) wavelength ranges. Its wavelength range corresponds to the vehicle response band-pass filter frequencies and is thus speed dependent. Simulations are also carried out to investigate the weak link and for the possibility to vary parameters that cannot be changed during on-track mea- surements. A multi-body system model of the passenger coach Bim 547.5 is used, together with recorded track data and vehicle speed from the on-track measurements. The varied parameters have rather low sensitivity and aect results to a small extent. Most impact has the randomly varying vertical track stiness which aects the vertical wheel–rail forces and axle box accelerations. In future work, it should be explored if it is possible – and in such case how – to separate the eects of varying track stiness from the track irreg- ularities. This to better understand when a vehicle response is linked more to the track irregularities or to the track flexibility. The weak link identified in the steps from track to vehicle should also be further explored, perhaps by extending the underlying model or evaluate a dierent set of measurements.
Spårlägesfel är avvikelser från den nominella spårgeometrin. De är en vik- tig excitationsmekanism i det dynamiska system som bana och fordon utgör och är viktiga att övervaka och åtgärda för att trafiken ska kunna flyta sä- kert och komfortabelt. Eftersom det vid mätningar för typgodkännande av fordon är viktigt att fordonet beter sig som förväntat och inom gränsvärden, är det viktigt att kunna beskriva spårlägesfel på ett sätt som är konsekvent och motsvarar hur fordonet ”känner av” dem. Det finns ett flertal olika metoder som kvantifierar de eekter spårläges- fel har på ett fordon som rör sig längs ett spår. Vanligast är att använda standardavvikelser, percentiler och maxvärden från spårsektioner med för- definierad längd. Dessa storheter korrelerar dock inte väl med den dynamiska fordonsresponsen, till exempel kan två spårsektioner med liknande maxvärden och standardavvikelse resultera i väldigt olika fordonsrespons. För att förbättra korrelationen mellan storheter för spårlägesfel och for- donsrespons rekommenderar tidigare forskning att använda multipel regres- sionsanalys för att även ta hänsyn till till exempel fordonets hastighet eller spårets kurvatur. Det finns flera alternativa metoder, till exempel derivator av spårlägesfel, överföringsfunktioner och fordonsfilter eller neurala nätverk. Generellt ger dock dessa metoder antingen fortfarande en viss osäkerhet i resultaten, eller så är de anpassade för vissa fordonstyper på enstaka järn- vägslinjer. Sammantaget är resultatet att den metod som föredras för att utvärdera spårlägesfel, fortfarande baseras på standardavvikelser. I den här avhandlingen används en enfrihetsgradsmodell som inspiration för att bryta ner excitationsvägen från spår till fordon i ett antal steg, som sedan undersöks genom att utvärdera mätdata från tre fordon i två forsk- ningsprojekt. En svag länk bland stegen identifieras, vilken visar signifikant lägre korrelationsvärde än övriga steg. Den svaga länken är steget från spatial andraderivata av spårlägesfel till axelboxacceleration dividerat med fordons- hastigheten i kvadrat. Ett variabelt våglängdsområde Dx introduceras som ett alternativ till de vanligt förekommande D1 (3–25 m), D2 (25–70 m) och D3 (70–150 m). Det variabla våglängdsområdet motsvarar de frekvenser som används för utvärdering av fordonsrespons och är därmed hastighetsberoende. Vidare används simuleringar för att undersöka den svaga länken och för möjligheten till parametervariationer. En flerkroppsmodell (MBS-modell) av passagerarvagnen Bim 547.5 används tillsammans med uppmätta data för spår och fordonshastighet. De parametrar som varieras visar sig ha låg käns- lighet och påverkar resultaten i liten utsträckning. Störst inverkan har den slumpmässigt varierande vertikala spårstyvheten, vilken påverkar de vertikala hjul–rälkrafterna och axelboxaccelerationerna. Fortsatt forskning bör undersöka om det är möjligt att – och i så fall hur – separera eekten av varierande spårstyvhet och spårlägesfel. Detta kan ge bättre förståelse för om fordonsrespons kopplar mer till spårlägesfelen eller till spårflexibiliteten. Den svaga länken som identifierats bör också undersö- kas ytterligare, förslagsvis genom att utöka den bakomliggande modellen eller analysera annan mätdata.

QC 20180517

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
This research aimed to understand the process of social innovation of the practice of street food on wheels in the city of João Pessoa-PB. For this, the notion of practice and social innovation developed by Shove, Pantzar and Watson (2012) was used, who understand the practice as an entity or performance constituted of interdependent elements (competences, materials and meanings) that combined become order it and reproduce it, and social innovation as the process from which practice emerges, persists, changes and disappears, when the connections between these three types of element are made, sustained, or broken. As for nature, it is a qualitative research in which the approach to practices for access the field was used, also known as Practice-Based Studies (EBP) (NICOLINI; GHERARDI; YANOW, 2003). Based on this approach, the methods of shadowing (CZARNIWASKA, 2014) and the interview to the double (NICOLINI, 2009a) were used, which together made it possible to capture more reliable data in the field of study. Associated with the mentioned methods, the technique of zooming in and zooming out (NICOLINI, 2009b) was also used. The following instruments were used to collect the data: participant observation techniques, informal conversations, semi-structured interviews, photo and video analysis, and field diary. The unit of analysis considered in this study was street food on wheels as a practice. For the analysis of the data and consequent elaboration of the results, the interpretation was used in light of the approach of Shove, Pantzar and Watson (2012), who were inspired by the EBPs. The results indicate that there is strong evidence that street food on wheels is undergoing the process of social innovation, since the material elements, skills and meanings have changed and are still in the process of change, it is already possible to identify differences between practice traditionally developed and the "new" practice. The first change identified in the "new" practice was with regard to gourmetization, the second was the structure and layout of the vehicle used, the third was the form of communication, mainly through the use of social networks via smartphones, the fourth was the management form and the fifth the use of spaces. In addition, a new understanding about the practice of street food on wheels has emerged and is expanding because of the transformations that have occurred in the practice.
Esta pesquisa teve como objetivo compreender a inovação social da comida de rua sobre rodas como prática na cidade de João Pessoa - PB. Para isso, foi utilizada a noção de prática e de inovação social desenvolvida por Shove, Pantzar e Watson (2012), que entendem a prática como uma entidade ou performance constituída de elementos interdependentes (competências, materiais e significados) que, combinados, passam a ordená-la e a reproduzi-la, e a inovação social como o processo do qual a prática emerge, persiste, muda e desaparece, quando as conexões entre esses três tipos de elemento são feitos, sustentados ou quebrados. Quanto à natureza, trata-se de uma pesquisa qualitativa, em que foi utilizada a abordagem das práticas para acesso ao campo, também conhecida como Estudos Baseados em Prática (EBP) (NICOLINI; GHERARDI; YANOW, 2003). Com base nessa abordagem, foram utilizados os métodos de shadowing (CZARNIWASKA, 2014) e o interview to the doble (NICOLINI, 2009a) que, juntos, possibilitaram a captura de dados mais fidedignos ao campo de estudo. Associadas aos métodos citados, também foi empregada a técnica de zooming in e zooming out (NICOLINI, 2009b). Para a coleta dos dados, recorreu-se aos seguintes instrumentos: técnicas de observação participante, conversas informais, entrevistas semiestruturadas, análise de fotografia e de vídeos, assim como o diário de campo. A unidade de análise considerada neste estudo foi a comida de rua sobre rodas como uma prática. Para a análise dos dados e consequente elaboração dos resultados, foi utilizada a interpretação à luz da abordagem de Shove, Pantzar e Watson (2012), que se inspiraram nos EBPs. Os resultados indicam que há fortes indícios de que a comida de rua sobre rodas esteja passando pelo processo de inovação social, pois os elementos materiais, as competências e os significados mudaram e ainda estão em processo de mudança, já que é possível identificar diferenças entre a prática desenvolvida tradicionalmente e a “nova” prática. A primeira mudança identificada na “nova” prática foi com relação à gourmetização, a segunda diz respeito à estrutura e layout do veículo utilizado, a terceira foi a forma de comunicação, principalmente, pelo uso das redes sociais via smartphones, a quarta foi a forma de gestão e a quinta o uso dos espaços. Além disso, um novo entendimento sobre a prática de comida de rua sobre rodas surgiu e está em expansão devido às transformações ocorridas na prática.

When developing three-phase drives for Electric Vehicles (EVs), it is essential to verify the controller design. This will help in understanding how fast and accurately the torque of the motor can be controlled. In order to do this, it is always better to test the controller using the software version of the motor or vehicle drivetrain than using actual hardware as it could lead to component damage when replicating extreme physical behavior. In this thesis, plant modelling of Permanent Magnet Synchronous Machine (PMSM) and vehicle drivetrain in MATLAB/Simulink for Model Based Design (MBD) is presented. MBD is an effective method for controller design that, if adopted can lead to cost savings of 25%-30% and time savings of 35%-40% (according to a global study by Altran Technologies, the chair of software and systems engineering and the chair of Information Management of the University of Technology in Munich) [1]. The PMSM plant models take effects like magnetic saturation, cross- coupling, spatial harmonics and temperature into account. Two PMSM models in d-q frame based on flux and inductance principles were implemented. Flux, torque maps from Finite Element Analysis (FEA) and apparent inductance from datasheets were used as inputs to the flux- and inductance-based models, respectively. The FEA of PMSM was done using COMSOL Multiphysics. The PMSM model results were compared with corresponding FEA simulated results for verification. A comparison of these PMSM models with conventional low fidelity models has also been done to highlight the impact of inclusion of temperature and spatial harmonics. These motor models can be combined with an inverter plant model and a controller can be developed for the complete model. Low frequency oscillations of drivetrain in EVs lead to vibrations which can cause discomfort and torsional stresses. In order to control these oscillations, an active oscillation damping controller can be implemented. For implementation of this control, a three-mass mechanical plant model of drivetrain with an ABS (Anti-lock Braking System) wheel speed sensor has been developed in this thesis. Analysis of the model transfer function to obtain the pole zero maps was performed. This was used to observe and verify presence of low frequency oscillations in the drivetrain. In order to include the effects of ABS wheel speed sensor and CAN communication, a model was developed for the sensor.
Testning av regulatorernas inställningar med hänsyn till snabbhet och noggrannhet i momentreglering är avgörande i trefasiga drivsystem för elektriska fordon. Oftast är det bättre att simulera i stället för att utföra experimentella tester där komponenter kan skadas på grund av fysisk stress. Detta kallas för Model Based Design (MBD). MBD är an effektiv metod för utformningen av styrningen som kan leda till kostnadsbesparingar på 25%-30% och tidsbesparingar på 35%-40% enligt en studie från Altran Technologies i samarbete med Tekniska universitet i München, TUM. Detta examensarbete behandlar en modell för en synkronmaskin med permanentmagneter (PMSM) samt en modell för drivlinan utvecklad i Matlab/Simulink för MBD. PMSMs modellen inkluderar magnetisk mättnad och tvärkoppling, MMF övervågor och temperatur. Två PMSM modeller har utvecklats. Den första baseras på magnetiskt flöde som erhålls från finita element beräkningar i COMSOL Multiphysics medan den andra bygger på induktanser givna från datablad. En jämförelse av dessa PMSM-modeller med konventionella low fidelity-modeller har också gjorts för att illustrera påverkan temperaturberoende och MMF övervågor. Modellerna kan kombineras med en växelriktarmodell för att utveckla en hel styrenhet. Lågfrekventa oscillationer i drivlinan leder till vibrationer som kan orsaka vridspänningar och försämra komforten i elfordonet. En aktiv dämpningsregulator kan implementeras för att kontrollera spänningarna men en mekanisk drivlinemodell med tre massor och en ABS (anti-lock braking system) hastighetssensor behövs. Den mekaniska modellen har implementerats och analyserats även beaktande en modell för en CAN kommunikationskanal. Oscillationer med låg frekvens kunde observeras i modellen.

碩士
國立交通大學
機械工程系所
104
The aim of this thesis is to design and analyze the body base of three-wheeled electric car, according to the specifications of 24th National Universities Super-mileage Competition organized by SAE International Taipei Section 2016 rule book. The work focuses on the important design parameters of the car and mechanical parameters, using the information and relevant approximations. In this study, a delta form body base of three-wheeled vehicle with two wheels in the rear axle (1F2R) is designed, analyzed and constructed with the specification respects to the requirement and regulation. The steering model which affects the frame design is chosen and calculated to get the best steering geometry. The driver’s seat and body shell are also designed with the best ergonomic posture and driving comfortably of the driver. The Solidworks software’s program is used to design the body base. Based on the design part, deformation on the chassis frame at load condition and stress distribution along each element can be determined. Finite element analysis (FEA) and computational fluid dynamics (CFD) of ANSYS program are utilized to simulate and analyze the static stability and fluid dynamics factor parameters which are evaluated with respect to various conditions to result a high suitable size of chassis frame and drag coefficient of body shell. In regard to the simulation, FEA and CFD are performed to find the value of safety factor (SF) rating of the frame and drag coefficient of the body shell. Other parts and equipment are also designed and fabricated by following the rule, regulation and requirements.

Loaded wheel tester (LWT) is a common testing equipment usually used to test the permanent deformation and moisture susceptibility of asphalt mixtures by applying moving wheel loads on asphalt mixture specimens. It has been widely used in the United States since 1980s and practically each Department of Transportation or highway agency owns one or more LWT(s). Compared to other testing methods for pavement materials, LWT features movable wheel loads that allow more realistic situations existing on the actual pavement to be simulated in the laboratory. Due to its potential of creating a condition of repetitive loading, the concept of using LWT for characterizing the properties of pavement materials were promoted through four innovative or modified tests in this study. (1) The first test focuses on evaluating the effect of geogrids in reinforcing pavement base courses. In this test, a base course specimen compacted in a testing box with or without geogrids reinforced was tested under cyclic loading provided by LWT. The results showed that LWT test was able to characterize the improvement of the pavement base courses with geogrids reinforcement. In addition, the results from this study were repeatable and generally in agreement with the results from another independent study conducted by the University of Kansas with similar testing method and base materials. (2) A simple and efficient abrasion test was developed for characterizing the abrasion resistance of pervious concrete utilizing LWT. According to the abrading mechanisms for pervious concrete, some modifications were made to the loading system of LWT to achieve better simulations of the spalling/raveling actions on pervious concrete pavements. By comparing the results from LWT abrasion tests to Cantabro abrasion tests, LWT abrasion test was proved effective to differentiate the abrasion resistances for various pervious concretes. (3) Two innovative LWT tests were developed for characterizing the viscoelastic and fatigue properties of asphalt mixtures in this study. In the test, asphalt beam specimens are subjected to the cyclic loads supplied by the moving wheels of LWT, and the tensile deformations of the beam specimens are measured by the LVDTs mounted on the bottom. According to the stress and strain, the parameters associated to the viscoelastic and fatigue properties of the asphalt mixture can be obtained through theoretical analyses. In order to validate the concepts associated with the above mentioned tests, corresponding conventional tests have also been conducted to the same materials in the study. According to the comparisons between the conventional and the LWT tests, the LWT tests proposed in this study provided satisfactory repeatability and efficiency.

Robots have growing potential to enter the daily lives of people at home, at work, and in cities, for a variety of service, care, and entertainment tasks. However, several challenges currently prevent widespread production and use of such human-centered robots. The goal of this thesis was first to help overcome one of these broad challenges: the lack of basic safety in human-robot physical interactions. Whole-body compliant control algorithms had been previously simulated that could allow safer movement of complex robots, such as humanoids, but no such robots had yet been documented to actually implement these algorithms. Therefore a wheeled humanoid robot "Dreamer" was developed to implement the algorithms and explore additional concepts in human-safe robotics. The lower mobile base part of Dreamer, dubbed "Trikey," is the focus of this work. Trikey was iteratively developed, undergoing cycles of concept generation, design, modeling, fabrication, integration, testing, and refinement. Test results showed that Trikey and Dreamer safely performed movements under whole-body compliant control, which is a novel achievement. Dreamer will be a platform for future research and education in new human-friendly traits and behaviors. Finally, this thesis attempts to address a second broad challenge to advancing the field: the lack of standard design methodology for human-centered robots. Based on the experience of building Trikey and Dreamer, a set of consistent design guidelines and metrics for the field are suggested. They account for the complex nature of such systems, which must address safety, performance, user-friendliness, and the capability for intelligent behavior.
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