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- Factory automation using OSI technologies: process automation in a transformers manufacturing plantPublication . Tovar, Eduardo; Oliveira, José Luís; Alves, Mário; Azevedo, Rui; Carvalho, Adriano; Sousa, Mário; Portugal, Paulo; Carvalho, José AugustoThis paper presents the work carried out in order to improve one of the areas of a factory plant, integrating it within the factory using different communication standards. The implementation described satisfies a set of data flow requirements and claims to be an example of different vendors and technologies integration. Distribution transformers have always been dried within ovens heated for the effect. This drying process has several drawbacks: a low efficiency dependence on the transformer volume and requiring a long time to complete. The new approach, presented in this paper, eliminates all those constraints.
- A framework for dependability evaluation of PROFIBUS networksPublication . Carvalho, José Augusto; Carvalho, Adriano; Portugal, PauloFieldbus networks have been assuming a high acceptance in the industrial environment, replacing the old centralized control architectures. Due to time critical nature of the tasks involved in these environments, the fulfillment of dependability attributes is usually required. Therefore the dependability is an important parameter on system design, which should be evaluated. Several factors can affect system dependability. The environmental ones are the most common and due to the particularity of the industrial environment this susceptibility is increased. In this paper it is proposed a framework based on fault injection techniques, supported by a hardware platform which emulates a fault set, representative of industrial environment scenarios, intending to disturb data communications on a PROFIBUS network. From these fault injection experiments, relevant data is gathered and a further analysis is carried out to evaluate dependability attributes.
- Modular data acquisition architecture for thin-film sensors surfacesPublication . Rodrigues, Nelson; Lima, José; Rodrigues, Pedro João; Carvalho, José Augusto; Laranjeira, Jorge; Maidana, Wellington; Leitão, PauloThin-film sensors surfaces are becoming popular to collect data in several specific and complex processes, namely plastic injection or metal stamping, allowing the digitization of such processes through the use of Internet of Things technologies. A particular challenge in such thin-film sensors surfaces is the data acquisition and signal conditioning system, which implementation is complex due to the characteristics of these sensors (e.g., low amplitude and noisy signals), but even more complex when implemented in real industrial processes, which are subject to harsh conditions, namely noise, dirt and aggressive elements. This work describes a modular data acquisition and signals conditioning system for thin-film sensors surfaces, meeting the requirements of scalability, robustness and low-cost, meaning that it can be easily expanded according to the number of sensors required for the application scenario.
- A data logger for educational purposes of a laboratory chemical reactor: an IoT approachPublication . Lima, José; Brito, Thadeu; Ferreira, Olga; Afonso, Maria João A.P.S.; Pinto, Vítor H.; Carvalho, José Augusto; Costa, Paulo Gomes daThis paper presents the development of an acquisition system and data logger from an existing set of three continuous stirred-tank reactors in series. The reactors are currently used in chemical engineering educational laboratories to perform kinetic and tracer experiments. In this sense, to accomplish the store data process, the volumetric flow rate and the concentration of tracer, reactants and/or products of the reaction must be acquired as a function of time. In the original experimental setup, only the signal conditioning system was operational, while the acquisition, visualization, and control systems were obsolete and damaged. Thus, a new system composed of an interface and real-time acquisition data is proposed alongside preserving the main reactor structure. A graphical user interface and the automation of the various actuators were developed based on worldwide usage and low cost, respectively. This system, based on a common 8-bit microcontroller and an application developed in Lazarus, allows the storage of the acquired data in a timeseries database. In this way, students can analyze the results later or in real time. Moreover, remote access allows controlling the reactor and getting data by the Internet of Things (IoT) resources. Additionally, the proposed system using IoT allows data to be shared with the community as a dataset.
- Experimental analysis of outage times for PROFIBUS networksPublication . Carvalho, José Augusto; Carvalho, Adriano; Portugal, PauloDistributed control systems operation strongly depends on the communication system performance. Therefore, their analysis becomes an important aspect to be considered, particularly in situations where communications have real-time constrains and the network operates on faulty environments. In this paper the behavior of PROFIBUS network in the pres-ence of faults is analyzed. This analysis is performed in an expe-rimental base supported by a real network. The network opera-tion is disturbed through a set of fault injection experiments from which performance metrics related with PROFIBUS out-age times are evaluated.
- Data acquisition, conditioning and processing system for a wearable-based biostimulationPublication . Oliveira, Leonardo Sestrem de; Kaizer, Raul; Gonçalves, João; Leitão, Paulo; Teixeira, João Paulo; Lima, José; Franco, Tiago; Carvalho, José AugustoData acquisition by electromyography, as well as the muscle stimulation, has become more accessible with the new developments in the wearable technology and medicine. In fact, for treatments, games or sports, it is possible to find examples of the use of muscle signals to analyse specific aspects related, e.g., to disease, injuries or movement impulses. However, these systems are usually expensive, does not integrate data acquisition with the muscle stimulation and does not exhibit an adaptive control behaviour that consider the pathology and the patient response. This paper presents a wearable system that integrates the signal acquisition and the electrostimulation using dry thin-film titanium-based electrodes. The acquired data is transmitted to a mobile application running on a smartphone by using Bluetooth Low Energy (BLE) technology, where it is analysed by employing artificial intelligence algorithms to provide customised treatments for each patient profile and type of pathology, and taking into consideration the feedback of the acquired electromyography signal. The acquired patient’s data is also stored in a secure cloud database to support the physician to analyse and follow-up the clinical results from the rehabilitation process.
- Avaliação do desempenho de redes PROFIBUS-DP suportada em técnicas de injecção de faltasPublication . Carvalho, José AugustoLimitações de natureza tecnológica condicionaram o desenvolvimento dos sistemas de controlo a uma abordagem que conduziu à centralização da sua estrutura. Com a evolução da tecnologia esta abordagem alterou-se e actualmente muitas das estruturas de controlo assentam sobre o paradigma da distribuição de tarefas. Neste contexto, as redes de comunicação desempenham um papel fundamental na estrutura e na operação do sistema de controlo. Nos níveis inferiores de controlo a comunicação é estabelecida através de redes de campo que fazem a interligação entre pequenos controladores sensores e actuadores, num processo tipicamente caracterizado pela troca de pequenas mensagens muitas das vezes de natureza cíclica, e usualmente com restrições temporais críticas. Dado o papel das redes de campo nos sistemas controlo, e fruto do aumento de complexidade, custos de desenvolvimento dos sistemas e sua exploração, e também do tipo de tarefas que desempenham, tornaram importante a consideração de aspectos relacionados com o efeito da operação da rede na disponibilidade do sistema, na segurança de pessoas, ou mesmo de impactos no ambiente em que se inserem. Assim, de uma forma genérica importa avaliar modos de operação das redes que potencialmente contribuam para uma diminuição da confiança no funcionamento dos sistemas que suportam. Neste contexto, a avaliação do funcionamento das redes de campo na presença de faltas, assume relevância na identificação das principais fontes de degradação de desempenho, que no limite possam levar o sistema a falhar a função para que foi especificado. No domínio da avaliação e da validação de sistemas os métodos experimentais são ferramentas poderosas, que podem ser utilizadas para alterar as normais condições de operação de um sistema e avaliar como desempenha nestas condições A técnica de injecção de faltas inclui-se nesta classe de métodos e permite introduzir de forma intencional e controlada erros no sistema. Assim, constitui uma solução eficaz na avaliação de sistemas complexos, para os quais a aplicação de outras técnicas é difícil, ou por vezes falha. Nesta dissertação pretende-se contribuir para a caracterização do funcionamento de uma das redes de campo mais difundidas em aplicações de automação industrial — o PROFIBUS-DP. A caracterização é centrada no seu funcionamento em modo degradado, designadamente quando a operação é perturbada por interferências de natureza electromagnética Este padrão de perturbação é susceptível de conduzir a rede para modos de operação que têm potenciais impactos na disponibilidade da rede e na sua capacidade de garantir o cumprimento de restrições temporais em aplicação de tempo-real. A área da avaliação do funcionamento na presença de faltas é uma área onde existe pouco trabalho publicado relativo ao comportamento do PROFIBUS~DP, e o que existe é manifestamente insuficiente para fornecer uma caracterização sólida do seu desempenho nestas condições de operação. Para suportar a avaliação da rede foi desenvolvido um ambiente de injecção constituído por uma infra-estrutura de injecção de faltas na qual se inclui uma rede PROFIBUSDP. A infra-estrutura de injecção implementa a técnica de injecção física de faltas, capaz de injectar faltas num ambiente distribuído de acordo com um processo estocástico. O hardware do módulo de injecção foi desenvolvido de forma a apresentar uma elevada controlabilidade do processo de injecção, assim como, de uma elevada resolução das faltas injectadas, permitindo injectar com precisão, faltas de um só bit e mais que um bit no barramento de comunicação. Os nós de comunicação foram desenvolvidos de acordo com a norma do PROFIBUS-DP. A estrutura do software e do hardware dos nós de comunicação permitem o acesso à camada de ligação de dados, e assim obter informação relevante relativa aos estados de operação do protocolo. A avaliação foi efectuada de forma a identificar eventos que afectem a organização das estações no anel lógico da rede PROFIBUSDP tendo sido identificados seis eventos com impactos importantes ao nível do desempenho da rede. Três destes relacionados com perdas de token, e os restantes associados a saídas não intencionais de estações do anel. A sua probabilidade foi inferida para diferentes cenários de faltas, assim como, foi avaliada a forma como os mecanismos de recuperação dos eventos identificados desempenham em condições de faltas. As experiências incidiram igualmente sobre a questão da resposta da rede nestas condições de operação. Neste contexto, quando a rede opera na configuração multi-mestre foram observados impactos significativos quer resposta temporal da rede, quer no tempo de recuperação dos mecanismos de tolerância a faltas. Este comportamento deixa antever uma má resposta da configuração multi-master em cenários de faltas.
- A modular cell controller architecture for a flexible manufacturing systemPublication . Carvalho, José Augusto; Carvalho, AdrianoThe need to optimize manufacturing systems operation has originated continuous effort in the developmeut of control system architectures. These have been freed from original rigid centralized structures evolving in such a way that attribute more autonomy to each control subsystem. The subsystems have then become specialized in the different tasks needed to control each manufacturing process. In the present work, an architecture for a cdl controller, composed of modules with a significant degree of autonomy, is presented.
- Real cockpit proposal for flight simulation with airbus A32x models: an overview descriptionPublication . Carvalho, José Augusto; Mendes, Andre C.; Brito, Thadeu; Lima, JoséThis paper describes the several steps to build an elaborate flight simulator cockpit, where the hardware is designed based on Mechatronic principles and the proposed software was developed using agile methodologies to create a Cyber-Physical System (CPS). Furthermore, this research attempts to simulate the real environment from an aircraft as close as possible with a real scale developed cockpit. Based on this, the presented paper contributions include: (1) The implementation of a complex dynamic system such as a CPS, where the Mechatronic system is part of it; (2) The deployment of a scale model of an Airbus A32x aircraft (one of the most used), integrating into a mathematical model adapted to the operation of an aircraft flight simulation system, regarding the physical forces involved. This project is also used to captivate the students’ motivation to the areas of technology such as electronics and programming and permits its development as a student project and thesis. Results allow validating the proposed cockpit.
- Real airplane cockpit development applied to engineering education: a project based learning approachPublication . Carvalho, José Augusto; Mendes, Andre C.; Brito, Thadeu; Lima, JoséEngineering education, the process of teaching knowledge and principles to the professional practice of engineering, can be done by resorting to several methodologies. Project Based Learning is a teaching method that allows students to get knowledge and skills by developing and solving complex problems or challenges, supported by a supervisor. In the presented work, a real airplane cockpit development is used as a case study for Mechanical, Mechatronics, Electrical, and Computer Science courses. Students are encouraged to develop modules to be applied in the cockpit and further integrated with other ones.