Browsing by Author "Ricco, Rodrigo Augusto"

Now showing 1 - 8 of 8
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    Applied sensor fusion : tuning parameters of CF and KF by means of evolution strategies.
    (2020) Santos, Talysson Manoel de Oliveira; Barroso, Márcio Falcão Santos; Ricco, Rodrigo Augusto
    From the point of view of metrology, inertial sensors acting separately present undesirable performance in the measurement of angular position. In order to provide measurements with greater precision and accuracy, the measures of each of these sensors are typically fused by means of filters. The performance parameters of these filters are hard to tune and several works have been using exhaustive search algorithm or manual experimental tests to tuning these parameters. However, the exhaustive search algorithm usually requires a large computational effort and adjusting parameters manually does not guarantee that the estimated parameters are optimized. In this work, it has been proposed the tuning of the Complementary Filter (CF) and the Kalman Filter (KF) through the heuristic method Evolutionary Strategies. Experimental results have shown that our method is a useful tool that considerably reduces the time to find the tuning of the FC and the FK. In addition, the use of the tuned FC and FK improved significantly metrological characteristics of the system. The use of Bland and Altman’s statistical method show that the measurements of the angular position have a good agreement with the actual angular position of a servo motor.
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    A circuit for automatic measurement of bifurcation diagram in nonlinear electronic oscillators.
    (2016) Ricco, Rodrigo Augusto; Verly, Anny; Amaral, Gleison Fransoares Vasconcelos
    Experimental bifurcation diagram is very helpful to describe the global behaviour of nonlinear electronic oscillators. The diagram allows insight gain of the oscillators behaviour for a parameter variation. However, when the bifurcation parameter is a resistance, experimental bifurcation diagrams are hard to achieve. In this case, if the potentiometer resistance has been used to change the gain, it is possible to replace the potentiometer by an alternative circuit using operational transconductance amplifier. This kind of circuit is presented in this work and experimental results are provided to piecewise affine Rössler electronic oscillator. The results obtained show a very good matching with the theoretical diagram. Then, if the bifurcation parameter is a resistance, voltage or current, we have implemented a circuit to extract the experimental bifurcation diagram of all nonlinear electronic oscillators.
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    Least-squares parameter estimation for statespace models with state equality constraints.
    (2021) Ricco, Rodrigo Augusto; Teixeira, Bruno Otávio Soares
    If a dynamic system has active constraints on the state vector and they are known, then taking them into account during modeling is often advantageous. Unfortunately, in the constrained discrete-time state-space estimation, the state equality constraint is defined for a parameter matrix and not on a parameter vector as commonly found in regression problems. To address this problem, firstly, we show how to rewrite the state equality constraints as equality constraints on the state matrices to be estimated. Then, we vectorise the matricial least squares problem defined for modeling statespace systems such that any method from the equality-constrained least squares framework may be employed. Both time-invariant and time-varying cases are considered as well as the case where the state equality constraint is not exactly known.
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    A low-cost wireless system of inertial sensors to postural analysis during human movement.
    (2019) Santos, Talysson Manoel de Oliveira; Barroso, Márcio Falcão Santos; Ricco, Rodrigo Augusto; Nepomuceno, Erivelton Geraldo; Alvarenga, Érika Lorena Fonseca Costa de; Penoni, Álvaro C. O.; Santos, Ana F.
    The dynamics of the human body has generated considerable recent research interest among scientist devoted to reducing the number of injuries and for performance improvement. In these studies, the investigation is usually addressed by means of commercial devices based on video recordings. However, these systems based on video recordings are usually expensive and require suitable laboratories for their use, which makes it unfeasible to collect data for activities outside controlled environments. In this work, we have shown that it is possible to present similar results with a much lower sampling rate, focusing on the evaluation of minimum and maximum values of the gait. As a result, it has been possible to develop a wearable, compact, portable, low-cost, wireless and embedded system to simultaneously analyze the three-dimensional angular position in eight points. This technology can be used in many sorts of environments. It is also possible to access information in real time with reliable and accurate measurements by means of simple modelling for the use of fusion techniques implemented in the microcontroller. Tests were conducted to evaluate the metrological characteristics of the system using the Complementary Filter (CF) and the Kalman Filter (KF). An algorithm of evolutionary strategies tuned both filters, providing errors of less than 5% for static situations in the measurement of the angular position over the entire system utilization range. Our results have been compared with the commercial system Qualisys Motion-Capture. The statistical method elaborated by Bland and Altman has been used. We have found our method yields a motion analyses in good agreement with results using post-processed video.
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    Mapping prior information onto LMI eigenvalue-regions for discrete-time subspace identification.
    (2020) Ricco, Rodrigo Augusto; Teixeira, Bruno Otávio Soares
    In subspace identification, prior information can be used to constrain the eigenvalues of the estimated state-space model by defining corresponding linear matrix inequality (LMI) regions. In this study, first the authors argue on what kind of practical information can be extracted from historical data or step-response experiments to possibly improve the dynamical properties of the corresponding model and, also, on how to mitigate the effect of the uncertainty on such information. For instance, prior knowledge regarding the overshoot, the period between damped oscillations and settling time may be useful to constrain the possible locations of the eigenvalues of the discrete-time model. Then, they show how to map the prior information onto LMI regions and, when the obtaining regions are non-convex, to obtain convex approximations.
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    MASLAB : um software interativo de simulação para apoio no ensino de modelagem e análise de sistemas lineares.
    (2022) Aguiar, Italo Almeida; Ribeiro, Rodrigo Geraldo; Ricco, Rodrigo Augusto; Ribeiro, Rodrigo Geraldo; Ricco, Rodrigo Augusto; Silva, Saul Emanuel Delabrida; Reis, Leonardo Vieira dos Santos
    Simulações aplicadas no contexto educacional são capazes de prover um considerável apoio no processo de aprendizado de determinada área de conhecimento. Este traba- lho propõe o desenvolvimento de um software de simulação interativo, gratuito e de código aberto para uso educacional no contexto da disciplina de Modelagem e Análise de Sistemas Lineares, nomeado MASLAB. Dentro do escopo da disciplina, MASLAB é capaz de compor e simular graficamente, dentro do escopo da disciplina, variações de cenários definidos pelos usuários, seja por visualização em tempo real ou por visuali- zação de um instante específico. Como forma se de testar as saídas do simulador, a metodologia de validação se propôs a replicar um experimento real por meio de dados previamente amostrados, de modo a se buscar uma proximidade relativa aos dados do experimento original. Por fim, são apresentados os resultados obtidos na replicação vir- tual do experimento real e a análise da proximidade esperada dos resultados obtidos no simulador.
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    Projeto de controladores PI robusto para processos de moagem empregando desigualdades matriciais lineares.
    (2020) Castro, Felipe Fuscaldi de; Braga, Marcio Feliciano; Euzébio, Thiago Antonio Melo; Braga, Marcio Feliciano; Euzébio, Thiago Antonio Melo; Campos, Victor Costa da Silva; Ricco, Rodrigo Augusto; Cota, Luciano Perdigão
    Controladores PI e PID são amplamente utilizados na indústria. Propõe-se para essa dissertação a comparação entre sintonias clássicas e robustas para controladores PI em processos de moagem na mineração. Inicialmente, é apresentado um modelo de sistema em cascata, cuja malha interna é composta por quatro malhas (do inglês, Single-Input Single-Output), e compara-se a utilização de controladores PI utilizando sintonia robusta em contraste com controladores que utilizam sintonias clássicas. Por fim, para circuitos de moagem fortemente acoplados e multivariáveis, estuda-se a implementação de desacopladores que tornem o controle do processo descentralizado e possibilitem a comparação de controladores PI robustos com controladores PI clássicos. A principal vantagem do uso de controladores robustos é permitir que uma mesma sintonia garanta a estabilidade para o processo ainda que ocorram incertezas no processo ou na modelagem do processo. Essas estratégias são testadas e avaliadas por meio de programas de simulação de processo e controle. Conclui-se que os controladores robustos resultam em desempenho melhor que os controladores clássicos e sua implementação melhora significativamente o desempenho do processo de moagem.
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    Subspace identification of linear systems with partial eigenvalue constraints.
    (2019) Ricco, Rodrigo Augusto; Verly, Anny; Paula, Marcus Vinicius de; Teixeira, Bruno Otávio Soares
    For subspace identification methods with eigenvalue constraints, the constraints are enforced by means of an optimization problem subject to LMI constraints. First principals or step response tests could be used as a source of auxiliary information in order to build LMI regions. In these cases, all the eigenvalues of the identified state-space model are subject to the same constraints. However, it often happens that the non-dominant eigenvalues have larger real part or larger natural frequencies. In this paper, we propose a two-step method in order to constrain the dominant dynamics of SISO models into LMI regions. In virtue of this result, in addition, the model eigenvalues could be constrained into disjoint LMI regions. Numerical examples illustrate the effectiveness of our proposed method.