Os objetivos desta pesquisa foram levantar os benefícios auferidos pela aplicação de melhorias na ergonomia dos postos de trabalho e no abastecimento planejado de peças em uma linha de montagem automotiva, bem como identificar e verificar até que ponto pode-se gerar vantagens competitivas na redução do tempo de montagem do veículo, com a aplicação de investimentos tecnológicos em ergonomia na área de manufatura. A metodologia Methods Time Measurement (MTM), foi escolhida para mensurar as diferenças de tempos de processo, e para coleta e identificação de dados. Foram observadas duas linhas de montagem: a primeira denominada de inovadora, construída há três anos com investimentos em soluções ergonômicas, tanto no abastecimento quanto no processo, e outra, tradicional, construída há 20 anos, com poucos investimentos na área. De posse dos dados necessários dos sistemas estudados e com o uso da tecnologia MTM, a pesquisa avalia e propõe meios de mensurar os ganhos com a redução de atividades que não agregam valor ao produto, com o intuito de viabilizar investimentos em ergonomia em postos de trabalho padronizados, manipuladores, instalações mais modernas e até possuir um time de planejamento de processos de produção mais robusto. Neste trabalho, analisa-se também a influência da ergonomia no custo do produto final, qualidade, retrabalhos, afastamentos médicos e absenteísmo entre outros. / The objectives of this research were raise the benefits gained for the application of improvements in the ergonomics of the workstation in the planned supplying of parts in the automotive assembly line. As well as identifying and verifying until the point that can generate competitive advantages in the assembly time reduction of the vehicle, with the application of technological investments in ergonomics in the area of manufacture. The methodology Methods Time Measurement (MTM) was chosen to measure the differences of times of process, and for collection and identification of data. Two assembly lines were observed, the first called innovator, built three years ago with investments in ergonomic solutions, as much in the supplying as in the process, and another traditional one built 20 years ago, with few investments in the area. Using all necessary data of the studied systems and with the use of MTM technology, the research evaluates and recommends ways to measure the profits with the reduction of activities that not add value to the product. With the intention to make possible investments in ergonomics standardized workstation, manipulators, more modern installations and until have a planning process production team more robust. This work, also analyze the medical influence of the ergonomics in the cost of the final product, quality, rework, medical dismissal and absenteeism among others.

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Low back problems are among the most common nonfatal occupational injuries reported in the United States, and account for substantial healthcare expenditures (e.g., medical care costs) and losses to worker productivity. A strong association has been well-documented between occupational exposure to repetitive trunk motion and low back problems, particularly among workers performing manual material handling (i.e., lifting) activities. A feature of repetitive motion believed important to the development of work-related musculoskeletal disorders (MSDs), including low back problems, is a lack of within-individual, between-cycle variation of physical exposure summary measures, e.g., when observed visually, the cycle-to-cycle motion pattern appears consistent. An active literature has emerged using concepts of motor control to improve ergonomists’ understanding of physical exposure variation (i.e., motor variability) arising from individual-level mechanisms during repetitive work. Fundamentally, for any particular individual, the onset of exposure to a repetitive physical activity (i.e., task training) involves a learning process during which motor control strategies are developed to accomplish the task effectively. The cycle-to-cycle variability of motor learning metrics, such as postural and task performance summary measures, has been observed to exponentially decay during task training. From an ergonomics perspective, a temporal reduction in postural variability may lead to greater cumulative loading and physiological fatiguing of the underlying muscle tissues (due to more consistent cycle-to-cycle movements), thus increasing MSD risk over time. However, it is not known if, or to what extent, physical task characteristics (e.g., work pace) modify the temporal behavior of motor variability during training of a repetitive occupational activity. Moreover, the relationships between motor variability, task performance, and muscle fatigue during occupational task training are not well understood. The goal of this dissertation was to present new information concerning occupationally relevant metrics of motor learning during training of a laboratory-simulated, repetitive lifting activity. In this study, participants performed 100 repetitions (i.e., cycles) of the lifting task in each of four experimental sessions (i.e., visits) at different combinations of box load (low or high) and work pace (slow or fast). Three main observations were discussed in this dissertation: (i) participants exhibited a greater temporal reduction in the cycle-to-cycle variability of trunk postural summary measures during training of a heavier-weighted and faster-paced lifting activity (Chapter 3), which may have facilitated increases in the efficiency and repeatability of box movements (Chapter 4), (ii) the cycle-to-cycle variability of the erector spinae (back) muscle activity summary measures increased, but the variability of the multifidus muscle activity summary measures decreased, over time during faster-paced lifting (Chapter 3), and (iii) a greater temporal increase in trunk postural variability (i.e., a more “flexible” trunk movement strategy) was generally associated with lesser electromyographic back muscle fatigue during training of the lifting task (Chapter 5). Collectively, these research findings may open pathways to the development of new task design criteria and ergonomic guidelines to promote motor variability in the workplace and, ultimately, improve workers’ musculoskeletal health.

Remanufacturing is an environmentally sound material recovery option which is essential to compete for sustainable manufacturing. The aim with remanufacturing at a majority of companies is to prolong physical product performance by delivering the same or betterthan-original product quality. In general, remanufacturing is an industrial process that brings used products back to useful life by requiring less effort than is demanded by the initial production process. Consequently, from a product life-cycle perspective, remanufacturing generates great product value. Remanufacturers lag behind manufacturers since they often face complex and unpredictable material and information flows. Based on a review of remanufacturing research, remanufacturing challenges in material and information flows can be classified into three groups: insufficient product quality, long and unstable process lead times, and an unpredictable level of inventory. While some remanufacturing researchers state that manufacturing and remanufacturing are significantly different, they have more in common than many other processes operations. Therefore, to sustain competitive remanufacturing, companies investigate an opportunity for improvement through the employment of lean production that generates significant benefits for manufacturers. In order to investigate the potential to address remanufacturing challenges by lean production, a Minimum time for material and information flow analysis (MiniMifa) method was developed. This method originates from the value stream mapping (VSM) method, broadly practiced to bring lean to manufacturing companies. The focus of MiniMifa was to collect empirical data on the identified groups of remanufacturing challenges from the remanufacturing perspective, and to provide a basis for the development of improvements originating from lean principles. Lean production was selected for this research due to its system perspective on material and information flows. Among the defined lean principles in remanufacturing, a pull principle was investigated at the case companies. The suggested principle demonstrated a reduction in lead time, followed by improvements in inventory level and product quality. However, in order to become lean, remanufacturers have to overcome three levels of lean remanufacturing challenges: external and internal challenges as well as lean wastes. Finally, this research reduces the gap between academia and industry by contributing with a possible solution to the identified remanufacturing challenges in material and information flows.

Les déficients visuels rencontrent de nombreuses difficultés lors de leur navigation web avec un lecteur d’écran, d’autant plus que les interfaces web deviennent de plus enplus riches de par leurs interactions et leur densité et diversité informationnelles. Cette thèse confronte ainsi 2 approches de l’accessibilité : l’approche dite « exhaustive » quivise à assurer l’accessibilité normative - garantissant l’accès à l’information par l’application de normes - et l’approche dite « holistique » qui vise à assurer l’accessibiliténormative mais également l’accessibilité effective - garantissant l’utilisabilité de l’interface - par la prise en compte du contexte d’utilisation des utilisateurs.Les 2 premières études ont analysé l’activité des utilisateurs déficients visuels qui a donné lieu à un modèle de la navigation web de ces utilisateurs. Ce modèle permet deconcevoir une interface suivant l’approche holistique par la prise en compte de leurs besoins, notamment celui de filtrage des informations non pertinentes et redondantes. Lorsde 3 expérimentations, les déficients visuels ont été confrontés à l'approche exhaustive par la retranscription exhaustive des informations et à l'approche holistique par l’accèsdirect au contenu associé à l’action réalisée. Les résultats montrent le bénéfice substantiel apporté par la version holistique concernant l’allègement de la charge cognitive etl’utilisabilité de l’interface selon les 3 critères : efficacité, efficience et satisfaction. Ainsi, cette thèse fournit des arguments probants pour promouvoir l’approche holistique pourguider la conception d’interfaces et l’élaboration de solutions d’assistance pour cette population. / Visually impaired people face many difficulties when navigating on the web with a screen reader, especially as web interfaces become increasingly rich because of theirdynamic interactions and their informational density and diversity. This thesis compares two approaches to accessibility: the current approach called "exhaustive" which aims toensure normative accessibility - guaranteeing access to information through the application of standards - and the approach called "holistic" which aims to ensure bothnormative and effective accessibility - guaranteeing the usability of the interface - by taking into account the context of its use (difficulties, strategies, needs, etc.).The first 2 studies analysed the activity of visually impaired users resulted in a model of the web navigation of these users. This model allows for designing interfaces followingthe holistic approach by taking into account their needs, especially the filtering of irrelevant and redundant information. In 3 experiments, visually impaired users performedtasks in two versions of websites: a version based on the holistic approach that gives access directly to content associated with the user’s action and a version using theexhaustive approach that transcribes exhaustively all the information present on the screen. The results show substantial benefit provided by the holistic version as regards thecognitive load and the usability of the interface according to 3 criteria: effectiveness, efficiency and satisfaction. Thus, this thesis provides cogent arguments promoting theholistic approach in order to guide the design of interfaces and the development of assistance solutions for screen reader users.

Heavy backpacks have been suggested to have a pathogenic role in experience of low back pain among children. We have conducted a repeated-measure study to investigate the backpack-induced changes in lumbo-pelvic coordination of forty gender-balanced college age students when they walked and jogged on a treadmill with two different types of backpacks: normal and ergonomically modified. The backpack-induced changes in lumbo-pelvic coordination were larger when carrying an ergonomically modified vs. a normal backpack as well as when jogging versus walking. The larger changes in lumbo-pelvic coordination when carrying an ergonomically modified backpack were likely due to kinematic restraints imposed by rigidity and enhanced attachments devised in the backpack for increased comfort. Given the role of lower back biomechanics in low back pain, the effects of such larger mechanical abnormalities in the lower back when carrying an ergonomically-modified backpack on risk of low back pain among children requires further investigation.

In recent decades, the development of computer-controlled manufacturing by adding materiallayer by layer, called Additive Manufacturing (AM), has developed at a rapid pace. The technologyadds possibilities to the manufacturing of geometries that are not possible, or at leastnot economically feasible, to manufacture by more conventional manufacturing methods. AMcomes with the idea that complexity is free, meaning that complex geometries are as expensiveto manufacture as simple geometries. This is partly true, but there remain several design rulesthat needs to be considered before manufacturing. The research field Design for Additive Manufacturing(DfAM) consists of research that aims to take advantage of the possibilities of AMwhile considering the limitations of the technique. Computer Aided technologies (CAx) is the name of the usage of methods and software thataim to support a digital product development process. CAx includes software and methodsfor design, the evaluation of designs, manufacturing support, and other things. The commongoal with all CAx disciplines is to achieve better products at a lower cost and with a shorterdevelopment time. The work presented in this thesis bridges DfAM with CAx with the aim of achieving designautomation for AM. The work reviews the current DfAM process and proposes a new integratedDfAM process that considers the functionality and manufacturing of components. Selectedparts of the proposed process are implemented in a case study in order to evaluate theproposed process. In addition, a tool that supports part of the design process is developed. The proposed design process implements Multidisciplinary Design Optimization (MDO) witha parametric CAD model that is evaluated from functional and manufacturing perspectives. Inthe implementation, a structural component is designed using the MDO framework, which includesComputer Aided Engineering (CAE) models for structural evaluation, the calculation ofweight, and how much support material that needs to be added during manufacturing. Thecomponent is optimized for the reduction of weight and minimization of support material,while the stress levels in the component are constrained. The developed tool uses methodsfor high level Parametric CAD modelling to simplify the creation of parametric CAD modelsbased on Topology Optimization (TO) results. The work concludes that the implementation of CAx technologies in the DfAM process enablesa more automated design process with less manual design iterations than traditional DfAM processes.It also discusses and presents directions for further research to achieve a fully automateddesign process for Additive Manufacturing. / AddMan

Over the last decade, Unmanned Aerial Vehicles (UAVs) have experienced an accelerated growth, and nowadays they are being deployed in a variety of missions that have traditionally been covered by manned aircraft. This unprecedented market expansion has created new and unforeseen challenges for the manufacturing industry which is now called to further reduce the idea-to-market times while simultaneously delivering designs of even higher performance. In this environment of uncertainty and risk, it is without a doubt crucial for the involved actors to find ways to secure their strategic advantage, and hence, implementing the latest design tools has become a critical consideration in every Product Development Process (PDP). To this end, a method that has been frequently applied in the PDP and has shown many successful results in the development of complex engineering products is Multidisciplinary Design Optimization (MDO). In general, MDO can bring additional knowledge regarding the best-suited designs much earlier in the process, and in this respect, it can lead to significant cost and time savings by reducing the total number of refinement iterations. Nevertheless, the organizational and cultural integration of MDO has been often overlooked, while at the same time, several technical aspects of the method for UAV design are still at an elementary level. On the whole, research on MDO is showing a slow progress, and to this date, there are many limitations in both the disciplinary models and the available analysis capabilities. In light of the above, this thesis focuses on the particulars of the MDO methodology, and more specifically, on how it can be best adapted and evolved in order to enhance the development process of UAVs. The primary objective is to study the current trends and gaps of the MDO practices in UAV applications, and subsequently to build upon that and explore how these can be included in a roadmap that will be able to serve a guide for newcomers in the field. Compared to other studies, the problem is herein approached from both a technical as well as organizational perspective, and thus, this research not only aims to propose techniques that can lead to better designs but also solutions that will be meaningful to the PDP. Having established the above foundation, this work shows that the traditional MDO frameworks for UAV design have been neglecting several important features, and it elaborates on how those novel elements can be modeled in order to enable a better integration of MDO into the organizational functions. Overall, this thesis presents quantitative and qualitative data which illustrate the effectiveness of the new framework enhancements in the development process of UAVs, and concludes with discussions on the possible improvement directions towards achieving more and better MDO capabilities.

As time goes by, people are no longer limited with the basic demands of survival, which started in the primitive society, and try to search for the satisfaction of spirit and comfortable sensation. At this time, furniture becomes to be the spiritualization carrier: they could contain the history and culture; they could make people relax and bring belongingness; they could show the preference of the designers. The furniture, or all kind of design, can be more than passionless implements. That is the subject I want to explore. Because of my educational background in interior design and architecture, I usually search a way to balance between technology and people's emotions, and try to keep the function together with physical contact of design at the same time. Due to the awareness of `people-oriented' concept, I researched and designed the Cocktail furniture series. The purpose of this thesis is to analysis this furniture set, which includes a chair, a coatrack and a table. The main theme of design is to create a relaxing area with soft curved lines and round shapes, and use as few pieces as possible to reduce the weight and waste of material. I used the computer graphics, algorithms and ergonomics, Thermal Forming and Computer Numerical Control techniques together to produce the building-block combination furniture with sustainable plywood and HDPE plastic. Furthermore the use of Ergonomic, such as replaceable pieces, applies the humanistic care in the furniture. Within the consideration of function and aesthetic demands, I want to create the kind of design that can bring the joy and comfort for customers.

Highly repetitive motion is associated with upper extremity musculoskeletal disorders among industrial workers.Current methods of estimating occupational exposure to "repetitiveness" provide information about the repetitiveness of joint motion, but fail to provide complete information about the repetitiveness of muscular exertion, a more biomechanically meaningful measure of repetition. This thesis introduces an innovative digital signal processing method, from which muscular exertion frequency was estimated. Specifically, time series recordings of muscle activity obtained with surface electromyography (sEMG) were processed with standard root-mean-square (RMS) amplitude calculations and then transformed from the time domain into the frequency domain. The mean power frequencies of the RMS-processed sEMG signals (MPF EMG) were then calculated to estimate muscular exertion frequency. In a laboratory-based validation study involving repetitive isometric hand gripping exertions, MPF EMG was compared to measures of muscular exertion frequency and joint motion frequency across a range of known exertion frequencies, intensities, and durations. Strong linear relationships were observed between MPF EMG and external measures of muscular exertion frequency. However, performance of MPF EMG as a measure of muscular exertion frequency may be improved with an increase of the signal to noise ratio in the sEMG data. Signal processing parameters were therefore investigated. Alternative processing parameters were suggested to minimize difference between MPF EMG and established methods of muscular exertion frequency. A second laboratory-based validation study compared MPF EMG to a measure of muscular exertion frequency and a measure of joint movement frequency during a simulated industrial task. Although a stronger linear relationship was observed between metrics of joint motion frequency and established measures of muscular exertion, the differences between measures were not meaningful and the relationship between MPF EMG and established measures was moderate-to-strong. The final phase of this thesis explored the application of the proposed techniques to field-based data collected during a study of ironworkers involved in construction stud-welding tasks. Limitations in data collection limited the analysis of MPF EMG in this study. The research presented in this thesis introduces a novel metric based on the frequency analysis of RMS processed sEMG data, and presents evidence that MPF EMG has potential to be a valuable assessment technique of exposure to repetitive muscular exertion.