Self-tuning algorithm for dsp-based motion control in cnc applications

This thesis describes the development of an adaptive control algorithm for Computerized Numerical Control (CNC) machines implemented in a multi-axis motion control board based on the TMS320C31 DSP chip. The adaptive process involves two stages: Plant Modeling and Inverse Control Application. The first stage builds a non-recursive model of the CNC system (plant) using the Least-Mean-Square (LMS) algorithm. The second stage consists of the definition of a recursive structure (the controller) that implements an inverse model of the plant by using the coefficients of the model in an algorithm called Forward-Time Calculation (FTC). In this way, when the inverse controller is implemented in series with the plant, it will pre-compensate for the modification that the original plant introduces in the input signal. The performance of this solution was verified at three different levels: Software simulation, implementation in a set of isolated motor-encoder pairs and implementation in a real CNC machine. The use of the adaptive inverse controller effectively improved the step response of the system in all three levels. In the simulation, an ideal response was obtained. In the motor-encoder test, the rise time was reduced by as much as 80%, without overshoot, in some cases. Even with the larger mass of the actual CNC machine, decrease of the rise time and elimination of the overshoot were obtained in most cases. These results lead to the conclusion that the adaptive inverse controller is a viable approach to position control in CNC machinery.

LIVE-Fab – CNC-Programmierung und Montageplanung in einer virtuellen Lernfabrik. Konzepte, Grundlagen, Technik, Anwendung

Am Institut für Arbeitswissenschaft und Betriebsorganisation (ifab) Universität Karlsruhe wird zurzeit das Projekt LIVE-Fab (Lernen in der virtuellen Fabrik) gemeinsam mit der Fachhochschule Landshut, Fachbereich Maschinenbau, durchgeführt. Dieses Projekt wird vom Bundesministerium für Bildung und Forschung (BMBF) im Rahmen des Programms „Neue Medien in der Bildung“ gefördert. Das Ziel des Projektes ist die Entwicklung eines anschaulichen Lehr- und Lernmodells für eine Fabrik als funktionierendes Ganzes. Dazu soll im Rechner eine Modellfabrik mit den Bereichen Wareneingang, Fertigung, Montage und Qualitätssicherung abgebildet werden. Die Fabrik mit ihren Anlagen (Maschinen, Transportsysteme etc.) und Materialflüsse soll in einem 3D-Modell visuell erfassbar sein. Die Grundlagen zur Schaffung einer virtuell funktionierenden Produktion einschließlich Anlagenplanung, Arbeitsvorbereitung, die Mechanismen, Kundenbestellungen und Qualitätsmanagement sollen in einzelnen Fallstudien den Studierenden vermittelt werden. Den Studierenden aus den Fachbereichen Maschinenbau, Wirtschaftsingenieurwesen, Elektrotechnik und Betriebswirtschaft mit technischer Ausrichtung soll mit der virtuellen Fabrik ein Werkzeug an die Hand gegeben werden, mit dem sie die komplexen, ineinander verzahnten Vorgänge eines Produktionsprozesses besser verstehen lernen. Dies bedeutet, dass in der virtuellen Fabrik die inhaltlichen Aspekte mehrerer vorgelagerter Vorlesungen kombiniert werden und dadurch ein Verbund zum Verständnis der Produktionsprozesse geschaffen wird.(DIPF/Orig.)

Architecture for machining process and production monitoring based in open computer numerical control

This paper proposes an architecture for machining process and production monitoring to be applied in machine tools with open Computer numerical control (CNC). A brief description of the advantages of using open CNC for machining process and production monitoring is presented with an emphasis on the CNC architecture using a personal computer (PC)-based human-machine interface. The proposed architecture uses the CNC data and sensors to gather information about the machining process and production. It allows the development of different levels of monitoring systems with mininium investment, minimum need for sensor installation, and low intrusiveness to the process. Successful examples of the utilization of this architecture in a laboratory environment are briefly described. As a Conclusion, it is shown that a wide range of monitoring solutions can be implemented in production processes using the proposed architecture.

Mechanistic approach to predict real machining time for milling free-form geometries applying high feed rate

An accurate estimate of machining time is very important for predicting delivery time, manufacturing costs, and also to help production process planning. Most commercial CAM software systems estimate the machining time in milling operations simply by dividing the entire tool path length by the programmed feed rate. This time estimate differs drastically from the real process time because the feed rate is not always constant due to machine and computer numerical controlled (CNC) limitations. This study presents a practical mechanistic method for milling time estimation when machining free-form geometries. The method considers a variable called machine response time (MRT) which characterizes the real CNC machine`s capacity to move in high feed rates in free-form geometries. MRT is a global performance feature which can be obtained for any type of CNC machine configuration by carrying out a simple test. For validating the methodology, a workpiece was used to generate NC programs for five different types of CNC machines. A practical industrial case study was also carried out to validate the method. The results indicated that MRT, and consequently, the real machining time, depends on the CNC machine`s potential: furthermore, the greater MRT, the larger the difference between predicted milling time and real milling time. The proposed method achieved an error range from 0.3% to 12% of the real machining time, whereas the CAM estimation achieved from 211% to 1244% error. The MRT-based process is also suggested as an instrument for helping in machine tool benchmarking.

Children with Cushing`s syndrome: primary pigmented nodular adrenocortical disease should always be suspected

Primary Pigmented Nodular Adrenocortical Disease (PPNAD) is a rare form of bilateral adrenocortical hyperplasia that is inherited in an autosomal dominant manner and leads to ACTH-independent Cushing`s syndrome (CS). PPNAD may be isolated or associated with Carney Complex (CNC). For the diagnosis of PPNAD and CNC, in addition to the hormonal and imaging tests, searching for PRKAR1A mutations may be recommended. The aims of the present study are to discuss the clinical and molecular findings of two Brazilian patients with ACTH-independent CS due to PPNAD and to show the diagnostic challenge CS represents in childhood. Description of two patients with CS and the many sequential steps for the diagnosis of PPNAD is provided. Sequencing analysis of all coding exons of PRKAR1A in the blood, frozen adrenal nodules (patients 1 and 2) and testicular tumor (patient 1) is performed. After several clinical and laboratory drawbacks that misled the diagnostic investigation in both patients, the diagnosis of PPNAD was finally established and confirmed through pathology and molecular studies. In patient 1, sequencing of PRKAR1A gene revealed a novel heterozygous 10-bp deletion in exon 3, present in his blood, adrenal gland and testicular tumor. The etiologic diagnosis of endogenous CS in children is a challenge that requires expertise and a multidisciplinary collaboration for its prompt and correct management. Although rare, PPNAD should always be considered among the possible etiologies of CS, due to the high prevalence of this disease in this age group.

Possible consequences of increasing life expectancy in Brazil: the perspective of a European historical demographer

Those over sixty years of age accounted for 6.6% of the total population of Brazil in 1985, in the Federal Republic of Germany this proportion was 20.3% in 1984. As early as 1950 it had been 14.5%. This proportion will not even be reached in Brazil in the year 2000 when persons aged sixty years and older are only projected to make up 8.8% of the total population. Similarly, in 1982/84 life expectancy at birth in the Federal Republic was 70.8 years for men and 77.5 for women; in Brazil the figures for 1980/85 were, by contrast, "only" 61.0 and 66.0. Against this background it is easy to understand why the discussion concerning an ageing society with its many related medical, economic, individual and social problems has been so slow in coming into its own in Brazil. As important as a more intensive consideration of these aspects may be in Brazil at present, they are, nevertheless, only one side of the story. For a European historical demographer with a long-term perspective of three of four hundred years, the other side of the story is just as important. The life expectancy which is almost ten years lower in Brazil is not a result of the fact that no one in Brazil lives to old age. In 1981 people sixty-five years and older accounted for 34.4% of all deaths! At the same time infants accounted for only 22.1% of total mortality. They are responsible, along with the "premature" deaths among youths and adults, for the low, "average" life expectancy figure. In Europe, by contrast, these "premature" deaths no longer play much of a role. In 1982/84 more than half of the women (52.8%) in the Federal Republic of Germany lived to see their eightieth birthdays and almost half of the men (47.3%) lived to see their seventy-fifth. Our biological existence is guaranteed to an extent today that would have been unthinkable a few generations ago. Then, the classic troika of "plague, hunger and war" threatened our forefathers all the time and everywhere. The radical transition from the formerly uncertain to a present-day certain lifetime, which is the result of the repression of "plague, hunger and war", led to unexpected consequences for our living together. Our forefathers were forced to live in closely knit Gemeinschaften in the interest of physical survival and to subordinate their egoistic goals to a common value, but now these pressures have, for the most part, fallen away. Correspondingly, this much more certain EGO has taken center stage. An ever greater number of us chooses to live life as single beings: the number of marriages is lower every year; the number of divorces is on the increase; in Berlin (West) more than half (sic! 52.3%) of all households are already composed on only one person. For the last dozen years the annual number of births in the Federal Republic has been insufficient to ensure population replacement. Not a population explosion but rather the opposite, a population implosion, is our problem. Human beings do not appear to be "social animals", as was axiomatically assumed for so long. They were only forced to behave as such for as long as "plague, hunger and war" forced them to do so. When these life endangering conditions no longer exist and life becomes certain even without their being integrated into a Gemeinschaft then humans suddenly show themselves more and more to be independent single beings. It is not the percentage of the population that is over sixty or sixty-five that is decisive in this context but rather how certain adults perceive their biological lives to be, since they are the ones who organize their lives, who build communities or who are ever more often willing only to enter into means-to-an-end personal unions without lasting or close ties and mutual responsibilities. There are many signs which seem to point to a development in this direction in Brazil as well. More and more adults in Brazil are caught up in the deep-seated transition from an uncertain to a certain lifetime. A third of them die after having reached their sixty-fifth birthday. It therefore seems to me to be high time that one began to give more consideration to the other side of the story in Brazil as well. And who is more suited intensively to consider the long-term perspectives than those engaged in the public health sector in whose competence, after all, such aspects, as "life certainty", "life expectancy" and "age at death" belong?

Reconhecimento, mensuração e divulgação na contabilização dos contratos plurianuais de construção: divergências entre o IASB, o FASB e o normativo português: a aplicação prática das normas nas empresas construtoras portuguesas.

Mestrado em Auditoria

Metodologia para a selecção de funções de maquinagem em sistemas CAD/CAM, para operações de fresagem multi-eixos

O presente trabalho aborda a construção de protótipos utilizando um centro de maquinagem CNC multi-eixos. É feita também uma abordagem ao novo formato que se encontra em desenvolvimento para a transferência de dados entre os softwares de CAD/CAM e os controladores CNC. Este novo formato de dados conhecido por STEP-NC tem como objectivo principal a comunicação directa entre os controladores CNC e os softwares de CAD/CAM, o que actualmente não é possível, uma vez que existe a necessidade de recorrer sempre a um pós-processador de dados para converter as trajectórias de maquinagem criadas pelos softwares de CAD/CAM em linguagem ISO específica para cada controlador CNC. A inovação introduzida com a elaboração deste trabalho consiste na obtenção de protótipos num centro de maquinagem CNC utilizando um único aperto do bruto de maquinagem. Para isso recorreu-se à fixação do bruto de maquinagem directamente à bucha do eixo rotativo (4º Eixo), permitindo assim que este rode quando existe a necessidade de maquinar uma outra face do protótipo, evitando desta forma a criação de novas fixações e a presença de um operador junto da máquina. A utilização deste novo método permite-nos ainda uma grande aproximação entre os centros de maquinagem CNC e as máquinas de prototipagem rápida (por adição de camadas) dado que em ambas se podem obter protótipos sem a intervenção do operador durante a totalidade da sua construção. Os testes práticos foram realizados no Instituto Superior de Engenharia de Lisboa (ISEL), e a peça utilizada como protótipo para a realização dos ensaios foi facultada por uma empresa especializada na construção de componentes aeronáuticos (LAUAK Portuguesa).

O modelo das demonstrações financeiras de acordo com o SNC

Neste trabalho, discutimos e analisamos as Demonstrações Financeiras (DF) elaboradas de acordo com a proposta do Sistema de Normalização Contabilística (SNC), apresentada pela Comissão de Normalização Contabilística (CNC), comparativamente com as DF preparadas de acordo com o Plano Oficial de Contabilidade (POC), em vigor em Portugal por imposição do Decreto-Lei n.º 410/89, de 21 de Novembro. Assim, marcamos separadamente os aspectos normativos que norteiam a execução dessas DF com referências comparativas entre elas, não com intuito de subjugar umas em detrimento de outras, mas de mostrar as suas diferenças em relação à essência, forma e finalidade. In this work, we discuss and analyze the Financial Reports (FR) made in accordance with the essay of Sistema de Normalização Contabilística (SNC) and presented by Comissão de Normalização Contabilística (CNC). In addition, we made a comparison with the FR prepared following the Plano Oficial de Contabilidade (POC) that is in use in Portugal by legal origin (Decreto-Lei n.º 410/89, de 21 de Novembro). Therefore, we emphasize the normative issues that drive FR construction with systematic comparisons between both. We do not aim to determine which one is the best normative, but to examine their differences related with essence, methods and goals.

I Jornadas de contabilidade e fiscalidade do ISCAP: a apresentação das demonstrações financeiras de acordo com o SNC

Jornadas de Contabilidade e Fiscalidade promovidas pelo Instituto Superior de Contabilidade e Administração do Porto, em Abril de 2009

NCRF 9 – locações: implicações fiscais e de auditoria

Dissertação apresentada ao Instituto Superior de Contabilidade e Administração do Porto para a obtenção do Grau de Mestre em Auditoria ORIENTAÇÃO: DR. JOÃO COSTA

Produção de PCB recorrendo a tecnologia Laser

O elevado nível de integração e miniaturização dos componentes existente nos dias de hoje, criam novos desafios na concepção de circuitos impressos. Neste trabalho são apresentados métodos para interligação entre componentes, em circuitos impressos com elevado número de ligações, recorrendo a tecnologia laser. Foi desenvolvida uma máquina CNC de três eixos, para posicionamento de um laser, mantendo o suporte para as operações tradicionais com ferramentas. O sistema foi concebido para a produção de circuitos impressos por laser (fresagem e furação), no entanto a compatibilidade com outras ferramentas e acessórios presentes, possibilitam a execução de outros processos no mesmo equipamento, como remoção da máscara de solda, soldadura de componentes, colocação de pasta de solda, gravação, inspecção visual, entre outros. Com este trabalho, demonstra-se a importância dos circuitos impressos na evolução da electrónica, assim como se apresentam soluções para a sua concepção.

Cutting forces and wear analysis of Si3N4 diamond coated tools in high speed machining

Si3N4 tools were coated with a thin diamond film using a Hot-Filament Chemical Vapour Deposition (HFCVD) reactor, in order to machining a grey cast iron. Wear behaviour of these tools in high speed machining was the main subject of this work. Turning tests were performed with a combination of cutting speeds of 500, 700 and 900 m min−1, and feed rates of 0.1, 0.25 and 0.4 mm rot−1, remaining constant the depth of cut of 1 mm. In order to evaluate the tool behaviour during the turning tests, cutting forces were analyzed being verified a significant increase with feed rate. Diamond film removal occurred for the most severe set of cutting parameters. It was also observed the adhesion of iron and manganese from the workpiece to the tool. Tests were performed on a CNC lathe provided with a 3-axis dynamometer. Results were collected and registered by homemade software. Tool wear analysis was achieved by a Scanning Electron Microscope (SEM) provided with an X-ray Energy Dispersive Spectroscopy (EDS) system. Surface analysis was performed by a profilometer.

A cellulosic liquid crystal pool for cellulose nanocrystals: structure and molecular dynamics at high shear rates

Cellulose and its derivatives, such as hydroxypropylcellulose (HPC) have been studied for a long time but they are still not well understood particularly in liquid crystalline solutions. These systems can be at the origin of networks with properties similar to liquid crystalline (LC) elastomers. The films produced from LC solutions can be manipulated by the action of moisture allowing for instance the development of a soft motor (Geng et al., 2013) driven by humidity. Cellulose nanocrystals (CNC), which combine cellulose properties with the specific characteristics of nanoscale materials, have been mainly studied for their potential as a reinforcing agent. Suspensions of CNC can also self-order originating a liquid-crystalline chiral nematic phases. Considering the liquid crystalline features that both LC-HPC and CNC can acquire, we prepared LC-HPC/CNC solutions with different CNC contents (1,2 and 5 wt.%). The effect of the CNC into the LC-HPC matrix was determined by coupling rheology and NMR spectroscopy - Rheo-NMR a technique tailored to analyse orientational order in sheared systems. (C) 2015 Elsevier Ltd. All rights reserved.