Most of the previous work on identification involves systems described by ordinary differential equations (ODEs). Many industrial processes and physical phenomena, however, should be modeled using partial differential...
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Most of the previous work on identification involves systems described by ordinary differential equations (ODEs). Many industrial processes and physical phenomena, however, should be modeled using partial differential equations (PDEs) which offer both spatial and temporal distributions that are simply not available with ODE models. systems described by a PDE belong to a class of system called distributedparameter system (DPS). This article presents a method for solving the problem of identification of uncertain DPSs using a differential neural network (DNN). The DPS, assumed to be described by a PDE, is approximated using the finite element method (FEM). The FEM discretizes the domain into a set of distributed and connected nodes, thereby, allowing a representation of the DPS in a finite number of ODEs. The proposed DNN follows the same interconnection structure of the FEM, thus allowing the DNN to identify the FEM approximation of the DPS in both 2D and 3D domains. Lyapunov's second method was used to derive adaptive learning laws for the proposed DNN structure. The identification algorithm, here developed in Nvidia's CUDA/C to reduce the execution time, runs mostly on the graphics processing unit (GPU). A physical experiment served to validate the 2D case. In the experiment, the DNN followed the trajectory of 57 markers that were placed on an undulating square piece of silk. The proposed DNN is compared against a method based on principal component analysis and an artificial neural network trained with group search optimization. In addition to the 2D case, a simulation validated the 3D case, where input data for the DNN was generated by solving a PDE with appropriate initial and boundary conditions over an unitary domain. Results show that the proposed FEM-based DNN approximates the dynamic behavior of both a real 2D and a simulated 3D system. (C) 2016 Elsevier B.V. All rights reserved.
This study focuses on the exact observability of a non-classical Euler-Bernoulli micro-beam equation. This non-classical model was derived based on the strain gradient elasticity theory, which is intended to explain t...
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This study focuses on the exact observability of a non-classical Euler-Bernoulli micro-beam equation. This non-classical model was derived based on the strain gradient elasticity theory, which is intended to explain the phenomenon of size effect at the micron scale. Spectral properties of the corresponding state operator are studied;an asymptotic expression for eigenvalues is calculated, and eigenfunctions are analyzed in order to check the necessary conditions for the exact observability of the system. By examining the eigenfunctions, it is shown that among non-collocated boundary outputs, only measurement of the non-classical moment at the root of the beam yields an admissible observation operator and also defines an exactly observable system. An alternative proof based on the multiplier method, which is commonly employed in the literature on the observability and controllability of infinite dimensional dynamical systems, is presented to provide a comparison between the time-and frequency-domain approaches.
Abstract This paper is concerned with designing a backstepping-based observer for a class of 1-dimensional parabolic distributed parameter systems whose output is a weighted spatial average of the state. We first show...
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Abstract This paper is concerned with designing a backstepping-based observer for a class of 1-dimensional parabolic distributed parameter systems whose output is a weighted spatial average of the state. We first show that an integral transformation converts the original system into another parabolic system with boundary observation if the weighting function satisfies a parameterized ordinary differential equation. Then the backstepping observer for the transformed system is available and an estimate of the original state is obtained through the inverse transformation. We also show that the estimation error exponentially converges to 0 in terms of the L 2 norm with arbitrary decay rate. Furthermore, a closed-form expression of the observer is provided for systems described by linear reaction-diffusion equations.
Sophisticated numerical models are created nowadays for the continuous casting of steel, partly thanks to the rapid development of information technology. These models are based on the numerical solutions of nonlinear...
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Linear infinite dimensional systems are described by a closed, densely defined linear operator that generates a continuous semigroup of bounded operators on a general Hilbert space of states and are controlled via a f...
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ISBN:
(纸本)9780791858264
Linear infinite dimensional systems are described by a closed, densely defined linear operator that generates a continuous semigroup of bounded operators on a general Hilbert space of states and are controlled via a finite number of actuators and sensors. Many distributed applications are included in this formulation, such as large flexible aerospace structures, adaptive optics, diffusion reactions, smart electric power grids, and quantum information systems. We have developed the following stability result: an infinite dimensional linear system is Almost Strictly Dissipative (ASD) if and only if its high frequency gain CB is symmetric and positive definite and the open loop system is minimum phase, i.e. its transmission zeros are all exponentially stable. In this paper, we focus on infinite dimensional linear systems for which a fixed gain linear infinite or finite dimensional controller is already in place. It is usually true that fixed gain controllers are designed for particular applications but these controllers may not be able to stabilize the plant under all variations in the operating domain. Therefore we propose to augment this fixed gain controller with a relatively simple direct adaptive controller that will maintain stability of the full closed loop system over a much larger domain of operation. This can ensure that a flexible structure controller based on a reduced order model will still maintain closed-loop stability in the presence of unmodeled system dynamics. The augmentation approach is also valuable to reduce risk in loss of control situations. First we show that the transmission zeros of the augmented infinite dimensional system are the open loop plant transmission zeros and the eigenvalues (or poles) of the fixed gain controller. So when the open-loop plant transmission zeros are exponentially stable, the addition of any stable fixed gain controller does not alter the stability of the transmission zeros. Therefore the combined plant plus control
In this paper, boundary control schemes are designed for a flexible aerial refueling hose subject to input deadzone, output constraint and external disturbances, based on partial differential equations (PDEs). Firstly...
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Abstract Proper orthogonal decomposition and subsequent Galerkin-projection is a common technique to obtain low-dimensional models for distributed parameter systems. In this paper a transformation of boundary conditio...
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Abstract Proper orthogonal decomposition and subsequent Galerkin-projection is a common technique to obtain low-dimensional models for distributed parameter systems. In this paper a transformation of boundary conditions into equivalent source terms for linear partial differential equations is used to set up such reduced-order models. This approach provides the means to consider boundary actuation in Galerkin-models, which is essential for the design of feedback controllers. Using the example of a one-dimensional convection-diffusion equation, the transient dynamics between the non-actuated and actuated steady state are described with such a reduced-order-model. Dynamic range and model accuracy are investigated in connection with the employed number of POD modes and the dynamics of actuation.
Abstract The present study focuses on boundary control of nonlinear distributed parameter systems and deals with Dirichlet actuation. Thus, a design approach of a geometric control law that enforces stability and outp...
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Abstract The present study focuses on boundary control of nonlinear distributed parameter systems and deals with Dirichlet actuation. Thus, a design approach of a geometric control law that enforces stability and output tracking of a given punctual output is developed based on the notion of the characteristic index. The control performance of the proposed strategy is evaluated through numerical simulation by considering two control problems. The former concerns the control of the temperature of a thin metal rod modelled by a heat equation with a nonlinear source, and the later concerns the control of concentration of a dye in liquid medium modeled by Fick law with nonconstant diffusivity.
This paper presents an observer-based motion control scheme for a single mobile robot to track and monitor a dynamic pollutant plume propagation in m-dimensional space. The spatiotemporal dynamics of the pollutant plu...
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ISBN:
(纸本)9781538635247
This paper presents an observer-based motion control scheme for a single mobile robot to track and monitor a dynamic pollutant plume propagation in m-dimensional space. The spatiotemporal dynamics of the pollutant plume is modeled by an advection-diffusion partial differential equation (PDE), and the plume front is described by a level set with a pre-specified threshold value. In the suggested control scheme, a Luenberger-type PDE observer using the local area concentration measurement taken from the onboard concentration sensor is first constructed to derive the concentration field knowledge over the entire spatial domain. Then, a motion control law is constructed based on the observer equation to drive the robot to track and patrol on the plume front. Rigorous convergence analysis of the suggested control algorithm is provided by the set stability concept and Lyapunov's direct method. Numerical simulations of planar pollutant plume front tracking and monitoring are demonstrated for the effectiveness of the proposed control scheme.
In this paper there are considered some applications arising from power engineering and involving hyperbolic equations of conservation laws. Focusing on the control of the flow in open channels, there is considered th...
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ISBN:
(纸本)9781538638422
In this paper there are considered some applications arising from power engineering and involving hyperbolic equations of conservation laws. Focusing on the control of the flow in open channels, there is considered the linearized model and a Lyapunov functional is associated. A linear multivariable controller with saturation is synthesized to make the Lyapunov functional exponentially decreasing along the solutions of the closed loop system. By integrating the Riemann invariants along the characteristics there is associated a linear system of difference equations. On this system the basic theory is constructed and the stability verified. Finally a research program for analyzing nonlinear cases is sketched.
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