938 resultados para Micro electro Mechanical System
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首先介绍了月表采样的新特点与存在的困难;根据月表环境、月表样品的特点以及嫦娥三期工程中对月表采样的要求,合理地选择了采样方式,研制出了一台六自由度机器人化月表采样器,并且对采样器的采样原理,机械系统和运动原理做了详细的分析;最后在石灰粉上做了采样实验,验证了多功能的机器人化月表采样器的基本功能与可行性。
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文章提出了一种基于五自由度机电系统的测控系统设计方法,并从机械系统构成、测控系统结构及软硬件设计方面论述了系统实现技术。针对系统特定的功能要求,文章详细介绍了位姿组合测量和各位姿自由度控制的测控方法,并应用模块化设计和数据流分析方法进行软硬件设计。通过实验进行系统特性分析,得到运行参数指标。实验证明这种设计方法和实现技术合理可行。
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轮式移动宜人机器人项目研究的主要目的是开发自主式仿人机器人样机 ,探索先进的机器人理论和技术。轮式移动宜人机器人由正交轮式移动平台、腰部、躯干及头部和双臂组成 ,共 2 1个自由度。整体结构包括 :电源系统、机械系统、控制系统和传感系统。电源系统采用车载电池供电。机械系统包括变刚度结构 ,提高了机器人与人交互作业的安全性。控制系统分为中央协调层和执行层结构。传感系统主要实现关节位置检测、姿态检测、力检测和视觉。文章讨论了此机器人的研究进展。
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微制作机器人技术是MEMS技术的一个重要分支,也是当前机器人研究领域的一个热点。本文分析了微操作机器人集成系统的特点,并针对微制作机器人系统研制中涉及的一些关键技术,如驱动、定位、检测和控制等技术进行了论述。
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针对远距离声源发射的水声信号微弱、水声接收设备电源能量有限的特点,提出一种功耗小、对无源元件误差灵敏度低、高增益放大的微弱水声信号通用放大电路。系统采用场效应管共源单调谐放大器为前置放大级,由四级级联低功耗运放构成带通滤波放大电路,省去传统的R、C低通网络,实现了对微弱水声信号的高增益放大和海洋背景噪声的归一化处理。通过计算电路网络传递函数极点证明了电路系统的稳定性。海上使用表明系统具有精度高、适应性强、电路稳定性好、功耗小等优点。
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通过对光纤微缆的受力分析,结合光纤微缆的特点设计并实现了光纤微缆收放系统.该系统采用恒张力控制收放光纤微缆,使光纤微缆随着水下机器人的运动释放和回收,减小了光纤微缆对水下机器人运动的影响,避免了光纤微缆的缠绕和损伤.
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为了使机器人跟踪给定的期望轨线,提出了一种新的基于机器人运动重复性的学习控制法.在这种方法中机器人通过重复试验得到期望运动,这种控制法的优点:一是对于在期望运动附近非线性机器人动力学的近似表达式的线性时变机械系统产生期望运动的输入力矩可不由估计机器人动力学的物理参数形成;二是可以适当的选择位置、速度和加速度反馈增益矩阵,从而加快误差收敛速度;三是加入了加速度反馈,减少了速度反馈,减少了重复试验的次数.这是因为在每次试验的初始时刻不存在位置和速度误差,但存在加速度误差.另外,这种控制法的有效性通过PUMA562机器人的前三个关节的计算机仿真结果得到验证。
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在基因芯片分析系统中,基因芯片荧光靶点图像的正确检测识别是基因特异性表达信息提取的必要前提。在荧光靶点检测识别过程中,由于沾污、瑕疵、离焦等因素的影响,荧光靶点图像的信噪比很低,很容易将污点、基片瑕疵等噪声点误识别为荧光靶点,而将沾污的荧光靶点误识别为噪声点。在原算法基础上,为进一步降低误识别率和提高检测精度,提出基于靶点分割图像重心和目标背景面积比的改进的荧光靶点检测识别算法。实验结果表明,与原算法相比,采用新算法将正确识别率提高到90%以上。
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Today most of the IC and board designs are undertaken using two-dimensional graphics tools and rule checks. System-in-package is driving three-dimensional design concepts and this is posing a number of challenges for electronic design automation (EDA) software vendors. System-in-package requires three-dimensional EDA tools and design collaboration systems with appropriate manufacturing and assembly rules for these expanding technologies. Simulation and Analysis tools today focus on one aspect of the design requirement, for example, thermal, electrical or mechanical. System-in-Package requires analysis and simulation tools that can easily capture the complex three dimensional structures and provided integrated fast solutions to issues such as thermal management, reliability, electromagnetic interference, etc. This paper discusses some of the challenges faced by the design and analysis community in providing appropriate tools to engineers for System-in-Package design
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Three experiments examined children’s and adults’ abilities to use statistical and temporal information to distinguish between common cause and causal chain structures. In Experiment 1, participants were provided with conditional probability information and/or temporal information and asked to infer the causal structure of a three-variable mechanical system that operated probabilistically. Participants of all ages preferentially relied on the temporal pattern of events in their inferences, even if this conflicted with statistical information. In Experiments 2 and 3, participants observed a series of interventions on the system, which in these experiments operated deterministically. In Experiment 2, participants found it easier to use temporal pattern information than statistical information provided as a result of interventions. In Experiment 3, in which no temporal pattern information was provided, children from 6-7 years, but not younger children, were able to use intervention information to make causal chain judgments, although they had difficulty when the structure was a common cause. The findings suggest that participants, and children in particular, may find it more difficult to use statistical information than temporal pattern information because of its demands on information processing resources. However, there may also be an inherent preference for temporal information.
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Parallel robot (PR) is a mechanical system that utilized multiple computer-controlled limbs to support one common platform or end effector. Comparing to a serial robot, a PR generally has higher precision and dynamic performance and, therefore, can be applied to many applications. The PR research has attracted a lot of attention in the last three decades, but there are still many challenging issues to be solved before achieving PRs’ full potential. This chapter introduces the state-of-the-art PRs in the aspects of synthesis, design, analysis, and control. The future directions will also be discussed at the end.
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Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Civil na Área de Especialização em Edificações
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A dependência energética das grandes economias mundiais, alertaram o mundo para a necessidade de mudar o comportamento relativo ao consumo de energia. O sector dos edifícios representa 40% dos consumos globais de energia na União Europeia, já no panorama nacional, o sector dos edifícios representa 28% dos consumos globais da energia, constituindo uma parte significativa no consumo global de energia, sendo portanto, essencial avaliar o desempenho energético dos edifícios, no sentido de promover a sua eficiência energética e beneficiar do grande potencial de economia de energia. Portugal à luz das linhas de orientação da União Europeia com o objectivo de instigar o aumento da eficiência energética nos edifícios, lançou o programa nacional para a eficiência energética nos Edifícios (P3E). Posteriormente, da transposição da Directiva 2002/91/CE para a ordem jurídica nacional surgiu o SCE, o RCCTE e o RSECE. Já em 2013, com a necessidade de transpor para a ordem da jurídica nacional a Directiva n.º 2010/31/EU, surge o Decreto-Lei n.º 118/2013, reunindo num só diploma o SCE, o REH e o RECS, promovendo uma revisão da legislação nacional, garantindo e promovendo a melhoria do desempenho energético dos edifícios. Através da presente dissertação, pretende-se avaliar o desempenho energético de uma pequena fracção de serviços existente tendo por base a metodologia regulamentar revogada do RSECE e a vigente metodologia regulamentar do RECS. Após apresentação dos dois regulamentos e da identificação das principais diferenças entre as duas metodologias regulamentares, procedeu-se ao enquadramento da fracção em estudo no âmbito de aplicação do RSECE e do RECS. Segundo os dois regulamentos a fracção não está sujeita a requisitos mínimos de qualidade térmica, nem a quaisquer requisitos energéticos e de eficiência dos sistemas técnicos, ao tratar-se de uma pequena fracção de serviços existente. Recorrendo ao software DesignBuilder, gerou-se o modelo da fracção em estudo, que através da simulação dinâmica multizona permitiu obter os consumos de energia anuais e a sua desagregação por utilização final. A partir dos consumos energia, determinaram-se os indicadores de eficiência energética de acordo com as duas metodologias, permitindo deste modo, proceder à classificação energética da fracção em estudo. De acordo com o RSECE a fracção em estudo obteve a classificação D, já segundo o RECS alcançou a classe C. Para aumentar a eficiência energética da fracção e consequentemente diminuir o consumo energético, foi proposto proceder à substituição das lâmpadas existentes por lâmpadas tubulares de tecnologia LED e à substituição do sistema de ventilação mecânico por um sistema de ventilação dimensionado para os novos valores de caudal de ar novo regulamentares. Com a implementação destas duas medidas a fracção em estudo melhoraria a sua classificação energética, exigindo um investimento baixo e apresentando um período de retorno de 1 ano e 5 meses. Segundo o RSECE passaria para a classe B, e aplicando a metodologia regulamentar do RECS alcançaria a classe B-.
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The goal of the present work was assess the feasibility of using a pseudo-inverse and null-space optimization approach in the modeling of the shoulder biomechanics. The method was applied to a simplified musculoskeletal shoulder model. The mechanical system consisted in the arm, and the external forces were the arm weight, 6 scapulo-humeral muscles and the reaction at the glenohumeral joint, which was considered as a spherical joint. The muscle wrapping was considered around the humeral head assumed spherical. The dynamical equations were solved in a Lagrangian approach. The mathematical redundancy of the mechanical system was solved in two steps: a pseudo-inverse optimization to minimize the square of the muscle stress and a null-space optimization to restrict the muscle force to physiological limits. Several movements were simulated. The mathematical and numerical aspects of the constrained redundancy problem were efficiently solved by the proposed method. The prediction of muscle moment arms was consistent with cadaveric measurements and the joint reaction force was consistent with in vivo measurements. This preliminary work demonstrated that the developed algorithm has a great potential for more complex musculoskeletal modeling of the shoulder joint. In particular it could be further applied to a non-spherical joint model, allowing for the natural translation of the humeral head in the glenoid fossa.
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Competitive sports participation in youth is becoming increasingly more common in the Western world. It is widely accepted that sports participation, specifically endurance training, is beneficial for physical, psychomotor, and social development of children. The research on the effect of endurance training in children has focused mainly on healthrelated benefits and physiological adaptations, particularly on maximal oxygen uptake. However, corresponding research on neuromuscular adaptations to endurance training and the latter's possible effects on muscle strength in youth is lacking. In children and adults, resistance training can enhance strength and mcrease muscle activation. However, data on the effect of endurance training on strength and neuromuscular adaptations are limited. While some evidence exists demonstrating increased muscle activation and possibly increased strength in endurance athletes compared with untrained adults, the neuromuscular adaptations to endurance training in children have not been examined. Thus, the purpose of this study was to examine maximal isometric torque and rate of torque development (RID), along with the pattern of muscle activation during elbow and knee flexion and extension in muscle-endurancetrained and untrained men and boys. Subjects included 65 males: untrained boys (n=18), endurance-trained boys (n=12), untrained men (n=20) and endurance-trained men (n=15). Maximal isometric torque and rate of torque development were measured using an isokinetic dynamometer (Biodex III), and neuromuscular activation was assessed using surface electromyography (SEMG). Muscle strength and activation were assessed in the dominant arm and leg, in a cross-balanced fashion during elbow and knee flexion and extension. The main variables included peak torque (T), RTD, rate of muscle activation (Q30), Electro-mechanical delay (EMD), time to peak RTD and co-activation index. Age differences in T, RTD, electro-mechanical delay (EMD) and rate of muscle activation (Q30) were consistently observed in the four contractions tested. Additionally, Q30, nonnalized for peak EMG amplitude, was consistently higher in the endurancetrained men compared with untrained men. Co-activation index was generally low in all contractions. For example, during maximal voluntary isometric knee extension, men were stronger, had higher RTD and Q30, whether absolute or nonnalized values were used. Moreover, boys exhibited longer EMD (64.8 ± 18.5 ms vs. 56.6 ± 15.3 ms, for boys and men respectively) and time to peak RTD (112.4 ± 33.4 ms vs. 100.8 ± 39.1 ms for boys and men, respectively). In addition, endurance-trained men had lower T compared with untrained men, yet they also exhibited significantly higher nonnalized Q30 (1.9 ± 1.2 vs. 1.1 ± 0.7 for endurance-trained men and untrained men, respectively). No training effect was apparent in the boys. In conclusion, the findings demonstrate muscle strength and activation to be lower in children compared with adults, regardless of training status. The higher Q30 of the endurance-trained men suggests neural adaptations, similar to those expected in response to resistance training. The lower peak torque may su9gest a higher relative involvement oftype I muscle fibres in the endurance-trained athletes. Future research is required to better understand the effect of growth and development on muscle strength and activation patterns during dynamic and sub-maximal isometric contractions. Furthennore, training intervention studies could reveal the effects of endurance training during different developmental stages, as well as in different muscle groups.