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Modélisation thermomécanique 3D en fraisage / 3D thermomechanical modeling in millingYousfi, Wadii 01 December 2015 (has links)
Cette thèse porte sur la modélisation thermomécanique 3D en configuration de fraisage. Afin de déterminer, pour chaque orientation de la plaquette et à chaque position angulaire de l’outil, le torseur d’action complet (efforts et moments) trois grandes parties ont été développées dans ce manuscrit.En se basant sur les lignes de glissement dans les trois zones de coupe, un modèle de coupe orthogonale a été développé. Le rayon d’acuité est intégré dans la modélisation et les résultats du modèle sont sensibles à ce paramètre. Le modèle a été validé par une confrontation avec des essais de rabotage.Pour deux types de plaquette, à arêtes droite et ronde, l’étude cinématique le long de l’arête de coupe a menée à la détermination du torseur cinématique instantanée en chaque point. Cette partie a permis de définir une nouvelle composante de vitesse de coupe dépendante de la position angulaire de l’outil. L’inclinaison de l’arête génère une vitesse parallèle à l’arête de coupe (perpendiculaire au plan de coupe en configuration orthogonale) qui participe au comportement cinématique de la matière dans les zones de cisaillement primaire et secondaire.Une modélisation volumique 3D dans les deux zones de coupe primaire et secondaire a permis de définir la cartographie de déformation et de vitesse de déformation. Cette approche a été basée sur les données cinématiques et les conditions aux limites appropriées. Les gradients de contraintes et de vitesses trouvés sont à l’origine de l’apparition des moments de coupe. / This thesis is focused on 3D thermomechanical modeling in milling configuration. In order to determine, for each insert orientation and each tool angular position, the complete actions torsor (forces and moments) three parts have been developed in this work.Based on the slip lines in the three cutting areas, an orthogonal cutting model was developed. The tool edge radius is built in modeling and model results are sensitive to this parameter. The model was validated by comparison with experimental tests.For two types of insert, with straight and round edge, the kinematic study along the cutting edge allowed to determine the instantaneous kinematic torsor at each point. This part has defined a new cutting velocity component dependent of tool angular position. The inclination of the edge generates a parallel velocity to the cutting edge (perpendicular to the cutting plane in orthogonal configuration) that participates in the kinematic behavior of the material in the primary and secondary shear zones.A 3D solid modeling in the primary and secondary cutting zones helped to define the cartography of strain and strain rate. This approach was based on kinematic data and appropriate boundary conditions. The gradients of stresses and velocities are the source of the appearance of the cutting moments.
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Gait knee kinematics of patients with ACL rupture : a 3D assessment before and after the reconstruction / Analyse cinématique de la marche chez des patients avec rupture du LCA : une évaluation 3D avant et après la reconstructionShabani, Bujar 25 February 2015 (has links)
La rupture du ligament croisé antérieure (LCA) conduit à une instabilité et à des modifications biomécaniques du genou. Actuellement, les patients présentant une lésion du LCA bénéficient généralement une reconstruction du LCA. L'analyse cinématique quantitative est un outil important pour acquérir une compréhension approfondie de la fonction articulaire du genou normal et pathologique au cours de la locomotion humaine. Ce travail est axé sur l'évaluation in vivo de la cinématique du genou chez les patients avec rupture du LCA, avant et après la reconstruction du LCA au cours de toutes les phases de la marche, en utilisant un nouvel outil d'évaluation 3D, quasi-rigide, en temps réel (KneeKGTM). Dans la première étude, des modifications cinématiques significatives ont été identifiées dans les genoux avec une rupture du LCA. Ces changements cinématiques pourraient mener à des contacts fémoro-tibiaux anormaux du cartilage pendant les activités quotidiennes, représentant potentiellement un mécanisme biomécanique de l'usure des articulations après une lésion du LCA. Dans la seconde étude, l'analyse 3D in vivo du mouvement a révélé que les genoux avec LCA reconstruits améliorent significativement leur extension par rapport aux genoux avec LCA déficient, mais il y avait encore une différence par rapport au groupe témoin sain. Dans le plan axial, le tibia reste en position interne significative par rapport à un groupe témoin, tandis qu'il n'y avait pas de différences significatives en translation antéro-postérieur et dans le plan coronal. Ces changements cinématiques pourraient conduire à une charge anormale dans l'articulation du genou et initier le processus d'atteinte dégénérative cartilagineuse à venir. Toutefois, les données cinématiques post-opératoires ont été collectées 10 mois après la chirurgie, ainsi un suivi plus long serait nécessaire pour évaluer si ces changements cinématiques persistent dans le temps, et leurs effets sur l'articulation / Because of the role of the ACL in knee joint’s biomechanics, it is essential to quantify the kinematics of ACL deficient and ACL reconstructed knee. In-vitro models bare the handicap of limited muscle simulation, while static, one-dimensional testing cannot predict the behavior of these groups of patients under realistic loading conditions. Currently, the most widely accepted method for assessing joint movement patterns is gait analysis. Respectively, 3D motion analysis is necessary to provide high reliability movement analysis. The purpose of the study was in-vivo evaluation of the behavior of the anterior cruciate ligament deficient (ACLD) and anterior cruciate ligament reconstructed (ACLR) knees during walking, using 3D, real-time assessment tool. Significant alterations of joint kinematics in the ACLD knee were revealed in this study by manifesting a higher flexion gait strategy and excessive internal tibial rotation during walking that could result in a more rapid cartilage thinning throughout the knee. In the other hand, even though ACLR knees showed some improvements in sagittal plane compared to ACLD knees, in axial plane there still exists difference compared to healthy control knees. These kinematic changes could lead to abnormal loading in knee joint and initiate the process for future chondral degeneration. However, the post-operative kinematic data were collected 10 months after surgery, so a longer follow-up is needed to evaluate if these kinematic changes persist in time, and their effects in joint degeneration
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Kinematická geometrie v rovině / Kinematic Geometry in the PlaneJavorská, Zdeňka January 2016 (has links)
Diploma thesis is divided into three chapters. In first chapter are explained elementary ideas of kinematic geometry in the plane included not just images but also dynamic files made in software GeoGebra. Second chapter is about specific motions in the plane. It describes construstion of the curves in synthetic and analytic way. Every motion has its own file with animation of that motion. Last chapter devoted to history of some curves and also to aplication of kinematic geometry in real life. This thesis is useful for university students of descriptive geometry, but it also may help as motivation for high school students, mainly students of technical schools.
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Error Calibration on Five-axis Machine Tools by Relative Displacement Measurement between Spindle and Work Table / 主軸・テーブル間の相対変位の測定に基づく5軸制御工作機械の誤差キャリブレーション法Hong, Cefu 26 March 2012 (has links)
Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第16841号 / 工博第3562号 / 新制||工||1538(附属図書館) / 29516 / 京都大学大学院工学研究科マイクロエンジニアリング専攻 / (主査)教授 松原 厚, 教授 松久 寛, 教授 西脇 眞二 / 学位規則第4条第1項該当
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Differential Evolution Based Interceptor Guidance LawRaghunathan, T 07 1900 (has links) (PDF)
Kinematics based guidance laws like the proportional navigation (PN) and many other linear optimal guidance laws perform well in near-collision course conditions. These have been studied thoroughly in the literature from all aspects, ranging from optimality to capturability, for planar or two dimensional interceptor-target engagements, and to a lesser extent, for three dimensional engagements. But guidance in widely off-collision course conditions like high initial heading errors has been relatively less studied. This is probably due to the inherently high nonlinearity of the problem, which makes it a far more difficult problem to solve. However, with increasing speed and agility of interceptors and targets, solutions of such problems have acquired an increased urgency, as has been reflected in the recent literature.
This thesis proposes a guidance law based on differential evolution (DE), a member of the evolutionary algorithms (EA) family. While EAs have been applied extensively to static optimization problems, they have been considered unsuitable for solving dynamic optimization or optimal control problems, due to their computationally intensive nature, and their consequent inability to produce solutions online in real-time, except for systems with very slow dynamics. This thesis proposes an online-implementable optimal control for interceptor guidance, a problem with inherently fast dynamics.
The proposed law is applicable to all initial geometries including those that involve high to very high heading errors. While interception by itself is a challenging task in the presence of high heading errors, an additional requirement of optimality is also imposed. The first part of the thesis considers only the 2-D kinematic model with high heading errors. In the second part, a 3-D realistic dynamic model, which includes a time-varying interceptor speed, thrust, drag and mass, besides gravity in the vertical plane of motion, and upper bound on the lateral acceleration, is considered, in addition to high heading errors. It is shown that the same structure of the law that is proposed for the 2-D kinematic model can also be used for the 3-D realistic model, if the rest of the complexities of moving from 2-D space to 3-D space, and from kinematics to dynamics is duly addressed.
The guidance law proposed does not require time-to-go, the estimation of which can be a difficult problem in high heading error scenarios in which the closing velocity can be negative. Easy to compute and simple to implement in practice, the proposed law does not need any of the techniques or methods from classical optimal control theory, which are complicated and suffer from several limitations. The empirical pure PN (PPN) law is augmented with a term that is a polynomial function of the heading error. The values of the coefficients of the polynomial are found by using the DE. The computational effort required for this low dimensional polynomial optimization problem is shown to be low enough to enable online implementation in real-time.
The performance of the proposed law in nominal and off-nominal conditions is validated through several simulations for the 2-D kinematic model, and the 3-D realistic dynamic model. The results are compared with the PPN, augmented PPN and the all-aspect proportional navigation (AAPN) laws in the literature, as per several criteria like optimality, peak latax required and robustness to off-nominal conditions. A successful online implementation of the proposed law for application in practice is also demonstrated.
An obvious limitation of optimization by soft computation methods like differential evolution is that no rigorous proof of either convergence or optimality exists for such methods. A fallback option in the form of a conventional guidance law is included in the scheme in case of failure of convergence, and an indirect proof of optimality is provided in the third and final part of the thesis. The same guidance problem is solved by direct multiple shooting method, and it is shown that the numerical results of the two methods compare favourably. The solution by the shooting method is optimal, but computationally far more intensive and takes a computation time of an order of magnitude that is at least one or two times that of the simulation time of the plant. It also needs a good initial guess solution that lies within the region of convergence, which can be a difficult task by itself. Moreover, the shooting method solution is only open loop, and hence applicable for the given model and initial conditions only. Whereas, the simplicity of the method proposed in the thesis makes the solution or guidance law computable in a fraction of the flight time of the engagement, thereby making it online implementable. Equally important, is the fact that it is closed loop, and hence robust to off-nominal conditions like variations in the plant model and parameters assumed in its design.
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Georeferering av ortofoto med UAV : En jämförelsestudie mellan direkt och indirekt georefereringAbdi, Joan, Joel, Johansson January 2020 (has links)
UAV (Unmanned Aircraft Vehicle) har revolutiontionerat ortofotoframställningen med sitt bidrag till ökad säkerhet, lägre kostnader samt effektivare arbetsgång vid framställning av ortofoton. Den traditionella flygfotogrammetrin med flygplan och utplacering av flygsignaler har varit den givna metoden i många år. Att flyga med UAV istället för flygplan sparar tid och pengar däremot är utplacering och inmätning av flygsignaler fortfarande tidskrävande och därför kostsamt. Företaget DJI har tagit fram en ny UAV med namnet DJI Phantom 4 RTK vilken stödjer möjligheten att använda satellitbaserad positionering för direkt georeferering. Den här studien har jämfört två olika georefereringsmetoder för framställning av ortofoton med UAV: direkt georeferering med NRTK (satellitbaserad positionering och nätverks-RTK) samt indirekt georeferering med olika antal markstödspunkter. Studien utfördes vid Högskolan i Gävle på en yta av åtta hektar. En undersökning av avvikelser i plan och höjd resulterade i acceptabla värden enligt de riktlinjer som följdes i HMK – Ortofoto (2017) samt de kontroller som genomfördes enligt SIS-TS 21144:2016. RMS-värdet i plan för den indirekta georefereringsmetoden ligger på 0,0102m. För den direkta georefereringsmetoden ligger RMS-värdet i plan vid användning av markstödpunkter mellan 0,0132 och 0,0148 m. Slutligen för den direkta georefereringsmetoden utan markstödpunkter är RMS-värdet i plan på 0,0136 m. RMS i höjd ligger inom intervallet 0,008-0,025 m. Det som redovisas i studien visar att en accepterad kvalitet av ortofoton går att erhålla baserat på de RMS-värden i plan och höjd med samtliga georefereringsmetoder som testats. Efter genomförda kontroller och utvärdering av de resultat kan det konstateras att de olika georefereringsmetoderna skiljer inte mycket åt varandra kvalitetsmässigt.Dock är den direkta georefereringsmetoden utan markstödpunkter mycket effektivare ur ett tidsperspektiv. Phantom 4 RTK är ny på marknaden och det behöver utföras mer forskning för att få en större insikt av dess potential. Dock krävs det mer forskning kring direkt georeferering för utvärdering av orotofotons kvalitet. / UAV (Unmanned Aircraft Vehicle) has revolutionized the creation of orthophotos with its contribution to increased safety, lower costs and more effective ways when making orthophotos. The traditional aerial photogrammetry with airplanes and placement of flight signals has been the standard method for years. To fly with UAV instead of an airplane is cheaper and saves time, however, the placement and measurements of flight signals is still time consuming and therefore expensive. The company DJI has developed a new UAV called Phantom 4 RTK that supports satellite based technology for direct georeferercing. This study compared two different measuring methods when producing orthophotos with UAV: direct georeferencing with NRTK (Network Real Time Kinematic) and indirect georeferencing when using different number of Ground Control Points (GCP). The study was conducted at the University of Gävle over an area of eight hectares. An investigation of the deviation in plane and height resulted in acceptable units based on the guidelines that were followed in HMK – Ortofoto and the controls that were followed from SIS- TS 21144:2016. The RMS value in plane for the indirect georeferencing method is 0,0102 m. For the direct georeferencing method the RMS value in plane when using ground control points is between 0,0132 and 0,0148 m. At last the RMS value for the direct georeferencing method without ground control points is 0,0136m. The RMS value in height is between the intervals 0,008-0,025 m. The data presented in this study show that an accepted quality in the orthophotos can be acquired based on the RMS values in plane and height for every georeferencing that was tested. After accomplished controls and evaluation the results show that the different georeferencing methods doesn´t differantiate too much from each other based on their quality. However, the direct georeferencing method with ground control points is more effective from a time perspective. Phantom 4 RTK is new on the market and more research is necessary in order to understand the potential of this technology and its posibility to integrate into society. More research is recquired for the direct georeferencing method in order to evaluate the quality of orthophotos.
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Měření pozice pohybujících se objektů pomocí robotické totální stanice / Position measurement of moving objects using a robotic total stationHoreličan, Tomáš January 2021 (has links)
Práca sa zaoberá objavujúcim sa nekonvenčným využitím moderných teodolitov, tiež známych ako Robotické Totálne Stanice (RTS), ako sledovací a navádzací systém, určením presnej pozície dynamicky sa pohybujúceho objektu. To sa týka najmä situácií, kde nie je možné využiť konvenčné polohovacie systémy akým je napríklad GNSS. Kinematicky určená poloha objektu kontinuálne sledujúcou RTS môže byť následne v reálnom čase využitá pre autonómnu navigáciu malých bezpilotných leteckých prostriedkov (UAV) poskytnutím referenčného súradnicového systému a okamžitej polohy v ňom. Podstatná časť práce je venovaná návrhu a realizácii vhodných experimentov, ktoré overia spoľahlivosť určovania presnej polohy objektu v presnom časovom okamžiku. Boli preverené stanice série S7 a S9 od spoločnosti Trimble a stanica S9 HP, ktorá disponuje frekvenciou kontinuálneho merania až do 10 Hz bola napokon využitá pre experimenty. Lokálny čas ovládacieho panelu TSC7, ktorý zabezpečuje komunikáciu so stanicou bol pomocou protokolu PTP synchronizovaný s lokálnym časom mini-počítača Raspberry Pi, ktorý následne poskytoval referenčné meranie skutočnej polohy objektu v čase. V závere sú zhrnuté výsledky experimentov.
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Design of a 5 Degree of Freedom Kinematic Stage for the Dual Crystal Backlighter Imager DiagnosticNguyen, Nicholas 01 June 2020 (has links)
The National Ignition Facility (NIF) is home to the world’s most energetic laser. The facility is one of the leading centers in inertial confinement fusion (ICF) experiments to research and understand sustainable fusion energy. To fully document and understand the physics occurring during experiments, precise diagnostics are used for a wide range of purposes. One diagnostic, the crystal backlighter imager (CBI), allows for X-ray imaging of the target at late stages of its implosion.
The aim of this project was to increase the current capabilities of the CBI diagnostic with the addition of a second crystal. This thesis focuses on the design development of the 5 degrees of freedom precision stages used to align each of the crystals. The motivations for the addition of a second crystal are covered in the introduction. A ray tracing model was generated to explore the required range of travel for both crystals, as well as explore potential effects of transitioning to a two-crystal system. The requirements of the precision stage are outlined based on the flaws of the current stage and areas with desired improvements. A dynamic analysis was performed on modified supporting hardware for CBI, to determine areas of interest in redesigning components for the two-crystal system. Further research is performed on commercial and literature methods used to design precision optomechanical stages. Finally, the design development is documented outlining the considered options, modifications to the existing system, and the proposed design solution. A design is proposed that meets the project requirements set at the beginning of design development.
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Modelování a řízení mobilních kolových robotů / Modelling and control of wheeled mobile robotsJonszta, David January 2008 (has links)
The thesis deals with modelling and control of wheeled mobile robots. The thesis introduces the mathematical models of diferentially driven mobile robot, robot with Ackerman steering and a skid steered robot. The thesis describes open-loop and feedback control. Feedback control is divided into point-to-point control, path following and trajectory tracking.
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Stanovení viskozity pro různé typy splaškových vod / Determination of the viscosity of various types of wastewaterGlombová, Pavla January 2015 (has links)
The aim of this diploma thesis is a description of viscosity as a physical characteristic of liquids, next a description of projecting different types of sewer systems (pressure sewer system, vacuum sewer system and gravity sewer system). There was a range of density and viscosity of wastewater experimentally determined. These values were compared with ordinary values used in practice. The practical part of this work consists of sampling wastewater from different types of sewer systems and various localities. Chemical-biological analysis was realized on those samples with defined density, then dynamic viscosity was measured by the rotary viscometer for various temperatures. Measured data are evaluated. Finally, a calculation related to the design of sewers was made.
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