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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Uppdatering av nationella höjdmodellen över begränsade områden med hjälp av UAS

Hedqvist, Emma, Jakobsson, Daniel January 2016 (has links)
I det här examensarbetet undersöks möjligheten att använda UAS över begränsade områden när den nationella höjdmodellen skapad av Lantmäteriet ska uppdateras. Ämnet var ett förslag från Lantmäteriet och huvudsyftet var att testa om UAS kan användas som komplettering till traditionell flygfotografering. Det blir allt vanligare att använda UAS inom till exempel geomatiken, eftersom det är ett bra verktyg när ett snabbt och effektivt resultat krävs. Lantmäteriet använder flygburen laserskanning vid genereringen av nationella höjdmodellen och den uppdateras med traditionell flygfotografering. Andra aspekter som undersökts i detta examensarbete var vilken mätosäkerhet kan uppnås med UAS vid framställandet av en DHM, vilken skillnad i lägesosäkerhet finns mellan studiens punktmoln jämfört med nationella höjdmodellen, samt mot punktmolnet genererat från traditionell flygfotografering och den ekonomiska aspekten vid användning av UAS. Detta utfördes genom att samla in data med hjälp av UAS över Furuvik, Gävle. Flyghöjden var 88 m över ett område på ca 1 ha. Därefter skapades en höjdmodell som kontrollerades enligt den tekniska specifikationen SIS-TS 21144:2013. I examensarbetet jämfördes punktmolnet som genererades från flygfoton tagna med UAS mot nationella höjdmodellen. Osäkerheten för den genererade höjdmodellen vid användandet av UAS visade ett bra resultat i höjd med en standardosäkerhet på 0,015 m. Punktmolnet genererat från Lantmäteriets bildmatchning låg 0,315-0,392 m under studiens punktmoln medan punktmolnet från laserskanningen låg 0,014-0,155 m över. Resultatet visade att användning av UAS är väldigt kostnadseffektivt när den nationella höjdmodellen över begränsade områden ska uppdateras. Det rekommenderas därför för Lantmäteriet att använda UAS för detta ändamål. Det blir mer än väl godkänt resultat och kostnaden är liten med tanke på resultatet, d.v.s. en metod för att verkligen kunna ajourhålla nationella höjdmodellen och komplettera traditionell flygfotografering över begränsade områden. Med denna metod slipper de vänta på att den traditionella flygfotograferingen ska ske. Tekniken går hela tiden framåt och inom en snar framtid kommer även laserskanning kunna ske med UAS. Det skulle vara intressant att se resultat av den metoden. Intressant skulle även vara att se om det i framtiden går att utesluta flygsignalering och verkligen kunna använda direkt georeferering för att spara tid ute i fält. / In this thesis we are going to investigate possibility of using UAS, over small areas, for updating national elevation model produced by the National Land Survey of Sweden. The subject of the thesis was proposed by the National Land Survey of Sweden. One of the main objectives of the study was to test if UAS can be used as a complement to traditional aerial photo. The use of UAS has increased over the years within for example geomatics, because it is a great tool when quick and effective results are required. The National Land Survey of Sweden uses airborne laser scanning to generate the national elevation model. The elevation model is then updated by traditional aerial photogrammetry. Other objectives that have been investigated in this study are what uncertainty can be expected with UAS when generating a DEM, the differences in uncertainty between the point cloud generated in this study to the national height model and to the point cloud generated from the traditional photogrammetry and the economic aspects when using UAS. For this purpose data was collected by UAS in Furuvik, Gävle. The flight height was 88 m over the area of about 1 ha. Then a DEM was created and controlled according to the technical specification SIS-TS 21144:2013. In this thesis a comparison between the point cloud generated in this study and the national elevation model has been performed. Uncertainty of the produced DEM using UAS showed very good result in height with a standard deviation of 0.015 m. The point cloud generated from the traditional photogrammetry was 0.315-0.392 m below the point cloud generated in this study, while the point cloud from laser scanning was 0.014-0.155 m above. The results showed that using UAS are very cost-effective to update the national elevation model. It is advisable for the National Land Survey of Sweden to update the national height model over small areas with this method. There will be more than efficient and the costs are small considering the result. In other word this method is to recommend when updating the national elevation model and can be used as a complement to traditional photogrammetry within limited areas. With this method, they will not have to wait for the traditional aerial photography to take place. The technology is constantly moving forward and in the near future laser scanning with UAS will occur. It would be interesting to see the results of that method. It would also be interesting to see if it is possible to exclude the ground control points, and really be able to use direct georeferencing to save time in the field.
2

Approche temporelle de la simulation et de la caractérisation des transducteurs ultrasonores capacitifs micro-usinés / Temporal approach of the simulation and the characterization of capacitive micromachined ultrasonic transducers (CMUTS)

Sénégond, Nicolas 17 December 2010 (has links)
Les transducteurs ultrasonores capacitifs micro-usinés sont aujourd'hui une nouvelle alternative à la transduction d'ondes ultrasonores. En comparaison avec la technologie piézo-électrique, ils offrent des potentialités en termes de production, de miniaturisation et d'intégration d'une électronique associée mais aussi en termes de performances. Néanmoins,leur mise en œuvre n'en est encore qu'à ces balbutiements et la compréhension de leurs comportements nécessite d'être approfondie. C'est dans ce cadre que s'inscrit le présent travail de thèse. Nous proposons, dans un premier temps, à l'aide d'un modèle numérique basé sur une mécanique linéaire de plaques multicouches, d'étudier l'effet des contraintes initiales sur le comportement statique. Dans un second temps, l'impact de la non-linéarité de la dynamique d'une cellule, puis d'un réseau de cellules, est étudiée en s'appuyant à la fois sur des mesures d'interférométrie et sur un modèle temporel intégrant les effets du fluide. Enfin, nous proposons une optimisation de l'excitation et l'utilisation de ces dispositifs en régime forcée pour la génération d'onde basse fréquence dans l'air et dans l'eau. / Capacitive tvIicromachined Ultrasound Transducers (cMUTs) are today a new alternative for the generation of ultrasonic waves. Compared lo the piezoelectric technology, theyoffer some potentialities in terms of reliability, production, miniaturization and electronicintegration but also in term of acoustic performance. Nevertheless, their implementationis relatively new and the understanding of their static and dynamic behaviors needs to bestudied further. This is in this context that this PhD is developed. We propose, in a firsttime, with the help of a numeric model based on the linear mechanic theory of multilayeredplates, to study the impact of initial stresses on the static behavior. In a second time, the impact of the nonlinearity on the dynamic of the cell first, and a cell array next, is studiedwith the help of a temporal model and measurements made by laser interferometry both.Finally, thanks to this dynamic study, a new operation mode of cMUTs is identified andverified. This one is based on the use of forced regime in air and water of these device togenerate low frequencies ultrasonic waves.
3

[en] DIGITAL HUMAN MODELS: CONCEPT, APPLICABILITY AND TECHNOLOGIES / [pt] DIGITAL HUMAN MODELS: CONCEITO, APLICABILIDADE E TECNOLOGIAS

JOSE LUIS AMARAL DE CARVALHO DE OLIVEIRA 16 January 2015 (has links)
[pt] A presente pesquisa tem como objetivo explorar as diferentes possibilidades de aplicação de Digital Human Models em projetos para as áreas do Design, Arquitetura, Arte e Engenharia. A partir da construção de um panorama temporal das culturas antigas, com a redescoberta de valores o período do Renascimento e culminando na Revolução Industrial, seguindo com o fator humano sendo agregado aos requisitos de projeto na Revolução Industrial. Do contexto histórico da curiosidade humana por replicar sua imagem até a implementação da representação da forma humana como parâmetro projetual para o setor produtivo. Espera-se com a pesquisa um melhor entendimento dos Digital Human Models como ferramenta para o desenvolvimento de projetos, sua aplicabilidade e perspectivas futuras, possibilitando assim a consequente disseminação de seu uso e maior acessibilidade ao usuário final, bem como um mapeamento das etapas e tecnologias de criação dos modelos. / [en] The present research intends to explore the different possibilities on the application of Digital Human Models on projects for Design, Architecture, Arts and Engineering. Building a panorama over the time starting on ancient cultures, rediscovering values from the antiquity on the period of Renascence, and culminating on the Industrial Revolution, following with the human factor been adopted as a project requirement during the Industrial Revolution. From a historical panorama of the human curiosity for replicating its own image until the implementation of human representation as project parameters into the productive sector. The main goal of this research is to obtain a better understanding of Digital Human Models as a tool to be used on projects development, its applicability and future perspectives, allowing with it a consequent dissemination of its use and a bigger accessibility to the final user, as well as a mapping of the stages and technologies on creating those models.
4

A Geometric Framework For Vision Modeling In Digital Human Models Using 3D Tessellated Head Scans

Vinayak, * 01 1900 (has links) (PDF)
The present work deals with the development of a computational geometric framework for vision modeling for performing visibility and legibility analyses in Digital Human Modeling (DHM) using the field-of-view (FoV), estimated geometrically from 3D tessellated head scans. DHM is an inter-disciplinary area of research with the prime objective of evaluating a product, job or environment for intended users through computer-based simulations. Vision modeling in the existing DHM’s has been primarily addressed through FoV modeling using right circular cones (RCC). Perimetry literature establishes that the human FoV is asymmetric due to unrestricted zygomatic vision and restrictions on the nasal side of the face. This observation is neither captured by the simplistic RCC models in DHM, nor rigorously studied in vision literature. Thus, the RCC models for FoV are inadequate for rigorous simulations and the accurate modeling of FoV is required in DHM. The computational framework developed in this work considers three broad components namely, the geometric estimation and representation of FoV, visibility and statistical visibility, and legibility of objects in a given environment. A computational geometric method for estimating FoV from 3D laser-scanned models of the human head is presented in this work. The strong one-to-one similarity between computed and clinically perimetry maps establishes that the FoV can be geometrically computed using tessellated head models, without necessarily going through the conventional interaction based clinical procedures. The algorithm for FoV computation is extended to model the effect of gaze-direction on the FoV resulting in binocular FoV. A novel unit-cube scheme is presented for robust, efficient and accurate modeling of FoV. This scheme is subsequently used to determine the visibility of 3D tessellated objects for a given FoV. In order to carry out population based visibility studies, the statistical modeling FoV and generation of percentile-based FoV curves are introduced for a given population of FoV curves. The percentile data thus generated was not available in the current ergonomics or perimetry literature. Advanced vision analysis involving character-legibility is demonstrated using the unit-cube with an improved measure to incorporate the effect of character-thickness on its legibility.
5

Användning av digitala tekniker för att utvärdera fysisk ergonomi : Användandet av IPS IMMA för analys samt förbättring av monteringslinjers ergonomi / Use of digital technology to assess physical ergonomics : The use of IPS-IMMA for analysis and improvement of assembly line ergonomics

Nyström, Sandra January 2021 (has links)
Bad worker health leads to an unnecessary increase of absent days and loss of money, particularly the more physically demanding jobs as in industry. This can be seen in both a broader perspective and also in the suffering of the individual. In order to stop this trend and lower the work injuries connected to bad ergonomics good, reliable, and preferably digital, methods have to be generated and evaluated. The aim of this master’s thesis is to investigate how Digital Human Modelling (DHM) tools can beused to evaluate physical ergonomics by building a real-life workstation in the DHM tool IPS IMMA. The workstation used here is based on a newly installed station at a large company placed in Skövde. This station was developed in collaboration of both technical specialists but also ergonomist consulting from the company Feelgood. The goal has therefore been to examine where in the process a DHM tool could be used and if it would contribute to the process. The methods chosen to investigate the use of DHM tools were to build a final model in IPS IMMA, which is based of four different versions of the workstation. By building four different versions of the workstation the process has simultaneously been analyzed and documented in order to compare the findings made in the program to the ones made in real life. The results have also been made in combination to finding the opportunities, challenges, and disadvantages with using DHM tools. The needed improvements within the DHM field have also been noted and discussed.
6

Analysis of vehicle ergonomics using a driving test routine in the DHM tool IPS IMMA

Romera Orengo, Javier January 2020 (has links)
The objective of this project is to develop a driving test using a Digital Human Modeling tool (DHM), specifically IPS IMMA, which will allow the evaluation of the ergonomics of the interior of vehicles as currently demanded by the automotive companies. Thus, improving both the design and the design process. This will involve a study of the driving and the tasks carried out by a real person to end up programming them in the DHM software. Based on this study an interface is suggested that guides engineers or ergonomists to design their own driving tests and enable them to evaluate their own designs without a high specialization in DHM tools and software. Taking into account the already present autonomous cars and their future development, the conceptual design of a two positions steering wheel (autonomous/manual driving) will be introduced as an example to be added in the driving test. This example is intended to show how DHM tools can be used to evaluate different designs solutions in early stages of the product development process. This project will be a contribution to one of the sections of the ADOPTIVE project carried out at the University of Skövde and in collaboration with Swedish automotive companies.
7

Optimization of a welding gun use case by using a time-based ergonomics evaluation method

Mora Quiles, Elia January 2022 (has links)
Nowadays virtual simulations are commonly used to solve problems regarding worker well-being or productivity in manufacturing companies. However, when it comes to finding a solution to one of these two objectives, the other usually tends to be secondary. In order to solve this problem, the Ergonomics in Production Platform (EPP) has been developed within research efforts at University of Skövde, which through the use of optimizations is able to obtain solutions where both objectives are taken into account. In turn, in order to address worker well-being, EPP makes use of the digital human modelling (DHM) tool. DHM tools are often used to evaluate simulations focused on studying human-machine interaction. However, as these software evolve and start to be able to reproduce complete motions, before they were only considering frames, new methods are needed to be able to assess risk factors such as time and prevent the occurrence of musculoskeletal disorders (MSDs). In order to assist in the development of EPP optimizations for simulations carried out in DHM tools, the time-based observational method RAMP was implemented, specifically the posture-related criteria of RAMP II. Using the Design and Creation research methodology, a welding gun case study located in China offered by Volvo Cars was used to evaluate the results of the optimizations carried out with EPP. For the evaluation of this case study, a manikin family of 10 members representing key cases of the Asian population was created for this task. Later, this task was recreated in IPS IMMA, where the 10 cases interacted with 3 welding guns to weld different spots on a piece. The analysis of this case study consisted of two distinct phases where the results of RAMP II implemented in EPP could be evaluated. The first phase focused on analyzing initial results of three different trajectories for all members of the family. The second phase consisted of optimizing one of the trajectories analyzed in the previous phase in such a way as to find the best welding angle of the gun to improve the results of the worst case in the first analysis. Three different factors were evaluated in this phase: RAMP II results versus the new angle, RAMP II results versus the results of other methods and the effect of productivity versus worker well-being. The results showed that welding angles of 116º and 80º were able to improve the values of the RAMP II criteria for the most disadvantaged manikin in the welding task. At the same time, it was observed that the higher the percentage of value added time, the higher the risk obtained in the analysis, worsening the worker's well-being.
8

A visualization approach for improved interpretation and evaluation of assembly line balancing solutions

Azamfirei, Victor January 2018 (has links)
Future manufacturing will be characterized by the complementarity between humans and automation (human-robot collaboration). This requires new methods and tools for the design and operation of optimized manufacturing workplaces in terms of ergonomics, safety, efficiency, complexity management and work satisfaction. There have been some efforts in the recent years to propose a tool for determining optimal human-automation levels for load balancing. Although the topic is quite new, it shares some similarities with some of the existing research in the area of robotic assembly line balancing. Therefore, it is crucial to review the existing literature and find the most similar models and methods to facilitate the development of new optimization models and algorithms. One of the two contributions that this thesis gives to the research world in the RALBP context is a literature review that involves high quality articles from 1993 to beginning 2018. This literature review includes visual and comprehensive tables—and a label system— where previous research patterns and trends are highlighted. Visualization of data and results obtained by assembly line optimization tools is a very important topic that has rarely been studied. Data visualization would provide a: 1. better comprehension of patterns, trends and qualitative data 2. more constructive information absorption 3. better visualization of relationships and patterns between operations, and 4. better contribution to data manipulation and interaction. The second contribution to research found in this thesis is the use of a human modelling (DHM) tool (called IPS), which is proposed as an assessment to the ergonomic risk that a robotic assembly line may involve. This kind of studies are necessary in order to reduce one of the most frequent reasons of work absence in our today society i.e. musculoskeletal disorders (MSDs). MSDs are often the result of poor work environments and they lead to reduced productivity and quality losses at companies. In view of the above, IPS was used in order to resolve the load handling problem between human and robot, depending on their skills and availability, while fulfilling essential ISO standards i.e. 15066 and 10218:1 and :2. The literature review made it possible to select highly useful documents in developing assumptions for the experiment and contributed to consider real features detected in the industry. Results show that even though IPS is not capable of calculating an entire robotic assembly with human-robot collaboration, it is able to simulate a workstation constituted of one robot and one human. Finite and assembly motions for both human and robot are expected to be implemented in future versions of the software. Finally, the main advantages of using DHM tools in assessing ergonomic risks in RALB can be extracted from the results of this thesis. This advantages include 1. ergonomic evaluation for assembly motions 2. ergonomic evaluation for a full working day (available in future version) and 3. essential ISO standard testing (available in future version).
9

A Geometric Approach for Discrete and Statistical Reach Analysis for a DHM with Mutable Supports

Reddi, Sarath January 2013 (has links) (PDF)
Conventional ergonomics analysis involves building physical mockups and conducting simulated operations, such that the constraints experienced by the human subjects can be directly observed. The limitations of this approach are that, they are resource intensive, less flexible for testing design variability and difficult to involve large number of subjects to account for population variability and thus, it is a reactive approach. With the advent of computer aided techniques, efforts are on to support ergonomics analysis processes for proactive design approaches. To achieve this, real scenarios are being simulated in virtual environments which include induction of representative human subjects into such envi-ronments and are termed as Digital Human Models (DHMs). The main challenge in the simulation of humans is to obtain the naturalness that is perceived in human interaction with the environment. This naturalness can be achieved by synergetically modeling the physical performance and cognitive aspects of humans in such a way that one aspect caters the requirements posed from the other. But in current DHMs, the various elements in the physical performance aspect are not in line with the requirements of higher level behav¬ioral/cogntive aspects. Towards meeting this objective, the influence of physical performance aspects of humans on achieving naturalness when DHM interacts with the virtual environment has been studied. In this work, the task of ’reach’ has been chosen for studying the influence of kinematic structure, posture modeling and stability aspects on achieving naturalness for both discrete and statistical humans. Also, a framework has been developed to give instructions based on relations between the segments of the body and objects in the environment. Kinematic structure is modeled to simulate the humans with varied dimensions taking care of the change of link fixations necessary for various tasks. The conventional techniques used to define kinematic structures have limitations in resolving the issues that arise due to change in link fixations. In this work a new scheme is developed to effectively handle precedence relationship sand change of configuration of the existing posture whenever link fixations change. The advantage with this new approach is that complex maneuvers which involve different link fixations and multiple fixations at a time can be managed automati¬cally without the user’s intervention. Posture prediction involves estimation of the whole body posture which a human operator is likely to assume while performing a task. It involves finding a configuration satisfy¬ing the constraints like placing the body-segments in preferred locations of the task space and satisfying the relations specified between body segments. There are two main chal¬lenges in this regard; one is achieving naturalness in the predicted postures and the other is minimizing the mathematical complexity involved in finding the real time solutions. A human-specific posture prediction framework is developed which can handle a variety of constraints and realize the natural behavior. The approach is completely geometry based and unlike numerical methods, the solutions involve no matrix inversions. Digital human models (DHMs), both as avatars and agents, need to be controlled to make them manipulate the objects in the virtual world. A relations based description scheme is developed to instruct the DHM to perform the tasks. The descriptions as a set of relations and postures involve simple triplets and quadruplets. As the descriptions constitute only the relations between actors, incorporating different behavior models while executing the relations is feasible through this framework. Static balancing is one of the crucial factors influencing the posture of humans. The stim¬ulus for the static balancing is the body’s self weight and is governed by the location of its point of application, namely the center of mass (COM). The main focus is on determin¬ing suitable locations for COM to infer about the mobility of the segments which supports the human structure in slow motion scenarios. Various geometric conditions necessary for support retaining, altering are deduced and developed strategies for posture transitions for effective task performance while maintaining stability. These conditions are useful in de¬termining the posture transition required to shift the COM from one region to the other and thus the behaviors realized while accomplishing the tasks are realistic. These behaviors are simulated through statically stable walking and sit to stand posture transition. One of the advantages of employing DHMs in virtual simulations is the feasibility of creat¬ing human models with varied dimensions. A comparative study is conducted on different methods based on probabilistic and statistic theory as an alternative to the percentile based approach with a view to answer the questions like ’what percentage of people can success-fully accomplish a certain task’ and ’how well can people perform when they reach a point in the operational space’. The case study is done assuming upper and lower arms of hu¬mans as a two link planar manipulator and their link lengths as random variables. Making use of statistical DHMs, the concept of task dependent boundary manikins is introduced to geometrically characterize the extreme individuals in the given population who would ac-complish the task. Simulations with these manikins would help designers to visualize how differently the extreme individuals would perform the task. All these different aspects of DHM discussed are incorporated in our native DHM developed named ’MAYAMANAV’. Finally this thesis will end with conclusions and future work discussing how these different aspects of DHM discussed can be combined with behavioral models to simulate the human error.
10

Natural Hand Based Interaction Simulation using a Digital Hand

Vipin, J S January 2013 (has links) (PDF)
The focus of the present work is natural human like grasping, for realistic performance simulations in digital human modelling (DHM) environment. The performance simulation for grasping in DHM is typically done through high level commands to the digital human models (DHMs). This calls for a natural and unambiguous scheme to describe a grasp which would implicitly accommodate variations due to the hand form, object form and hand kinematics. A novel relational description scheme is developed towards this purpose. The grasp is modelled as a spatio-temporal relationship between the patches (a closed region on the surface) in the hand and the object. The task dependency of the grasp affects only the choice of the relevant patches. Thus, the present scheme of grasp description enables a human like grasp description possible. Grasping can be simulated either in an interactive command mode as discussed above or in an autonomous mode. In the autonomous mode the patches have to be computed. It is done using a psychological concept, of affordance. This scheme is employed to select a tool from a set of tools. Various types of grasps a user may adopt while grasping a spanner for manipulating a nut is simulated. Grasping of objects by human evolves through distinct naturally occurring phases, such as re-oreintation, transport and preshape. Hand is taken to the object ballpark using a novel concept of virtual object. Before contact establishment hand achieves the shape similar to the global shape of the object, called preshaping. Various hand preshape strategies are simulating using an optimization scheme. Since the focus of the present work is human like grasping, the mechanism which drives the DHMs should also be anatomically pertinent. A methodology is developed wherein the hand-object contact establishment is done based on the anatomical observation of logarithmic spiral pattern during finger flexion. The effect of slip in presence of friction has been studied for 2D and 3D object grasping endeavours and a computational generation of the slip locus is done. The in-grasp slip studies are also done which simulates the finger and object response to slip. It is desirable that the grasping performance simulations be validated for diverse hands that people have. In the absence of an available database of articulated bio-fidelic digital hands, this work develops a semi-automatic methodology for developing subject specific hand models from a single pose 3D laser scan of the subject's hand. The methodology is based on the clinical evidence that creases and joint locations on human hand are strongly correlated. The hand scan is segmented into palm, wrist and phalanges, both manually and computationally. The computational segmentation is based on the crease markings in the hand scan, which is identified by explicitly painting them using a mesh processing software by the user. Joint locations are computed on this segmented hand. A 24 dof kinematic structure is automatically embedded into the hand scan. The joint axes are computed using a novel palm plane normal concept. The computed joint axes are rectified using the convergence, and intra-finger constraints. The methodology is significantly tolerant to the noise in the scan and the pose of the hand. With the proposed methodology articulated, realistic, custom hand models can be generated. Thus, the reported work presents a geometric framework for comprehensive simulation of grasping performance in a DHM environment.

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