We study integral delay systems with exponential kernel. The computation of the Lyapunov matrix is shown to reduce to an auxiliary system of differential equations with boundary conditions of mixed type. We prove that...
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We study integral delay systems with exponential kernel. The computation of the Lyapunov matrix is shown to reduce to an auxiliary system of differential equations with boundary conditions of mixed type. We prove that the solution of the auxiliary system exist and is unique if the integral delay system satisfies the Lyapunov condition. Copyright (C) 2019. The Authors. Published by Elsevier Ltd. All rights reserved.
Various applications use high-pressure pumps for waterjet machining. A cutting head generates the waterjet, which is capable to cut hard and brittle materials. These cutting heads induce pressure fluctuations with res...
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Various applications use high-pressure pumps for waterjet machining. A cutting head generates the waterjet, which is capable to cut hard and brittle materials. These cutting heads induce pressure fluctuations with respect to an a priori unknown switching pattern. This paper applies a graph-based modelling methodology on complex high-pressure networks representing different waterjet facilities. For that, network sections are assigned to homogeneous segments, each representing a local pressure state. Segments are subsequently interconnected along their fluid flow paths, resulting in a lumped parameter model. In this way, the graph-based methodology offers a flexible modelling to cope with various network topologies. The resulting mathematical models of different waterjet facilities have been verified for specific cutting head switching patterns. Measurements on a test bench show that a desired accuracy is obtained over a wide operating range from 0 to 2.45 1/min, even for a fast switching period of 0.5 seconds. (C) 2019, ifac (International Federation of Automatic control) Hosting by Elsevier Ltd. All rights reserved.
The paper investigates the newly designed zinc-airflow battery cells and aims to build a mathematical model for such energy storage systems. The work builds on the electro-chemical characterization performed in a prev...
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The paper investigates the newly designed zinc-airflow battery cells and aims to build a mathematical model for such energy storage systems. The work builds on the electro-chemical characterization performed in a previous study and aims to move the focus towards a modelling framework suitable for battery management/control/supervision. In this endeavour, the internal process is abstracted in order to obtain a behavioural mathematical model which concentrates the parameters in a representative input-state-output model. Ideally, the result will replicate the behaviour and allow to simulate the real cell functioning and thus to represent a meaningful tool for design techniques which are using model-based predictions. Copyright (C) 2019. The Authors. Published by Elsevier Ltd. All rights reserved.
The paper treats the control of the jumping robot during the stance phase using the fractal model of the system. Considering an actuation system based on the Electro-Rheologic (ER) fluid controller, a fractal model is...
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The paper treats the control of the jumping robot during the stance phase using the fractal model of the system. Considering an actuation system based on the Electro-Rheologic (ER) fluid controller, a fractal model is inferred. The linearized model and nonlinear models are studied and control frequential laws are proposed using YKP criterions. Observer models are proposed for linear and nonlinear systems and the global stability for "system-observer" is studied by Lyapunov techniques. Numerical simulations are presented. Copyright (C) 2019. The Authors. Published by Elsevier Ltd. All rights reserved.
The connectedness of region of asymptotic stability of time-delay systems is proved. We apply this to prove one important property of optimal control of a time-delay system. Namely, we have established that the region...
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The connectedness of region of asymptotic stability of time-delay systems is proved. We apply this to prove one important property of optimal control of a time-delay system. Namely, we have established that the region of asymptotic stability, which corresponds to the optimal control with respect to a functional of a certain type, will be wider than the region of asymptotic stability, corresponding to any admissible control. Copyright (C) 2019. The Authors. Published by Elsevier Ltd. All rights reserved.
In this work, a dynamic model of a twin screw feeder, for continuous tablet manufacturing, has been developed. In particular, a First Order Plus Dead Time (FOPDT) model has been suggested. The delayed dynamics depends...
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In this work, a dynamic model of a twin screw feeder, for continuous tablet manufacturing, has been developed. In particular, a First Order Plus Dead Time (FOPDT) model has been suggested. The delayed dynamics depends on operating conditions, equipment design and physical properties of the bulk solid. Model parameters are estimated by fitting the model to experimental data. Due to the nonlinear input-output relationships and the time delays involved, a Nonlinear Model Predictive control (NMPC) is investigated to maintain an accurate mass flow rate, with the ultimate goal to improve product homogeneity in an inherently complex process. The performance of the designed control system is found to be satisfactory in a wide operating range and its potential use in a continuous manufacturing process is worth being investigated in the future. Copyright (C) 2019. The Authors. Published by Elsevier Ltd. All rights reserved.
In this work, a transit network design problem is presented. The problem is identified as a typical large-scale complex system. Subsequently, it is decomposed into its sub-components. The first two sub-components, whi...
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In this work, a transit network design problem is presented. The problem is identified as a typical large-scale complex system. Subsequently, it is decomposed into its sub-components. The first two sub-components, which encompass the network design and frequency setting problems, are then tackled by means of an innovative solution framework that combines a genetic algorithm with agent-based travel demand modelling. An analysis of results obtained from applying the proposed method to different testing scenarios shows that it is capable of designing transit networks that address the individual and collective perspectives of different stakeholders. Hence it can be used as a viable decision support tool for policy makers in the transportation network sector. (C) 2019, ifac (International Federation of Automatic control) Hosting by Elsevier Ltd. All rights reserved.
Nonminimum phase systems are presented in many industrial processes bringing some difficulties in their control scheme. In this paper we propose a methodology to tune multi-input-multi output proportional-integral-der...
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Nonminimum phase systems are presented in many industrial processes bringing some difficulties in their control scheme. In this paper we propose a methodology to tune multi-input-multi output proportional-integral-derivative controllers that deals this particularity. The controller design employed here is based in an attainable trajectory determination, for the nonminimum phase system, that considers performance and robustness metrics. Based on that, two different tuning procedures are proposed: an optimization problem, in the frequency domain, that involves nonconvex quadratic matrix inequalities with a linear matrix inequality restriction and a time domain optimization of the simulated system. The methods are an alternative for tuning this kind of system leading the process to the best operational scenario presenting stability, robustness and limited control actions. (C) 2019, ifac (International Federation of Automatic control) Hosting by Elsevier Ltd. All rights reserved.
In the classic controlsystems analysis a known difficulty is to determine a transient output response when non-zero (discontinuous) initial conditions are present. This difficulty is overcome by means of the presente...
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In the classic controlsystems analysis a known difficulty is to determine a transient output response when non-zero (discontinuous) initial conditions are present. This difficulty is overcome by means of the presented input-output jump relations. For a system with order n and relative degree r = n - m, these relations relate the jump discontinuities of the input and its derivatives up to the order m - 1 to the jump discontinuities of the output and its derivatives up to the order n - 1. A simplified behavior theory is used in deducing these straightforward relations. A simple, complete solution to the initial conditions problem that uses neither generalized derivatives nor ad hoc assumptions is then presented. A detailed example illustrating this solution is included. Copyright (C) 2019. The Authors. Published by Elsevier Ltd. All rights reserved.
This paper investigates tracking performances attainable in iterative learning control of linear discrete-time systems with unknown parameters in the presence of observation noise. The transient and steady-state perfo...
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This paper investigates tracking performances attainable in iterative learning control of linear discrete-time systems with unknown parameters in the presence of observation noise. The transient and steady-state performances are measured by the decay rate and the magnitude of tracking error, respectively. A trade-off relation between these performances is represented by the product of the direct terms of the plant and the learning law. Numerical simulations are conducted to observe the trade-off behaviors. Copyright (C) 2019. The Authors. Published by Elsevier Ltd. All rights reserved.
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