Identifying the underlying structure of a network from observed data is an important problem across various disciplines. Given the general ill-posed nature of the problem, since in many cases, multiple plausible netwo...
详细信息
Identifying the underlying structure of a network from observed data is an important problem across various disciplines. Given the general ill-posed nature of the problem, since in many cases, multiple plausible network models can explain the data, this article concentrates on characterizing classes of models providing possible explanations. Specifically, we explore linear models that can account for observed data in the form of wide-sense stationary processes accommodating the potential presence of feedback loops and direct feedthroughs. To achieve this, we leverage key insights from the theory of graphical models. In particular, we extensively employ Pearl-Verma Theorem in causal discovery which allows one to recover all minimal network structures compatible with the observed data. We adapt such a result to deal with stochastic processes and reinterpret it as a Gram-Schmidt orthogonalization procedure in a suitable Hilbert space. This reinterpretation allows us to characterize all minimal networks explaining a set of data, which have the property of not having any algebraic loops. Copyright (C) 2024 The Authors. This is an open access article under the CC BY-NC-ND license (https://***/licenses/by-nc-nd/4.0)
The main contribution of this paper is a model structure for the identification of affine quasi linear parameter-varying (qLPV) models in state-space (SS) form. The special case where the state is unknown and part of ...
详细信息
ISBN:
(数字)9781665467469
ISBN:
(纸本)9781665467469
The main contribution of this paper is a model structure for the identification of affine quasi linear parameter-varying (qLPV) models in state-space (SS) form. The special case where the state is unknown and part of the scheduling vector is considered. In this case the model is always recurrent in the states which demands for an internal dynamics approach, e.g. a Recurrent Neural Network (RNN). The proposed approach is based on a structured RNN developed by Lachhab et al. [1], but extends the original model via so-called gates, neural network structures which are responsible for the recent success of RNNs on various areas of application in Machine Learning, such as the Long short-term memory (LSTM) network and the Gated Recurrent Unit (GRU). The use of gates has multiple advantages: The complexity of the models scheduling map and hence its approximation capabilities are increased, while preserving its affine quasi-LPV structure and the applicability of the results on global asymptotic stability (GAS) by Lachhab et al. [1] at the same time. The performance of the proposed approach is demonstrated by comparison with two other RNN-based approaches on two nonlinear systemidentification benchmark problems.
Turntable servo systems are important experimental equipment used for semi-physical simulation and testing of aircraft, which have very strict requirements for tracking performance. To achieve high-precision servo per...
详细信息
In this work, the reachability analysis of a multirotor aircraft is developed using a zonotopic reachability algorithm, and the results are compared to a Monte Carlo simulation approach. To illustrate this study, a Pa...
详细信息
ISBN:
(纸本)9781665414968
In this work, the reachability analysis of a multirotor aircraft is developed using a zonotopic reachability algorithm, and the results are compared to a Monte Carlo simulation approach. To illustrate this study, a Parrot Mambo minidrone is considered, for which a complete nonlinear Simulink model is available. To achieve the reachability analysis, the closed-loop system can be approximated by a linear invariant system that can easily be exploited. In this way, forward and backward reachable sets can be evaluated and intersected. We determine that only the short-term analysis is necessary as the system is closed-loop and stabilized. For the Monte Carlo simulation analysis, on the other hand, both the original nonlinear model or its linear approximation can be used and we show equivalent results. This study is a preliminary step towards the analysis of upset flight conditions of multirotor aircrafts.
ANNs (Artificial Neural Networks) have been used successfully in various systemidentification applications. However, in general, the ANN-based identification is primarily non-parametric in nature, as the system infor...
详细信息
ISBN:
(纸本)9781728108995
ANNs (Artificial Neural Networks) have been used successfully in various systemidentification applications. However, in general, the ANN-based identification is primarily non-parametric in nature, as the system information is hidden within the neural network architecture, which is not transparent enough to be modeled explicitly. In this paper, a series parallel neural network architecture has been proposed for parametric systemidentification, whose weights are optimized using adaptive learning through training data, collected from unknown nonlinear system. The optimized weights of the proposed ANN structure are then directly utilized to model the unknown system, in terms of an equivalent discrete transfer function model. The estimated model using proposed technique can be effectively utilized to analyze, test and control the unknown system dynamics. Simulation examples with measurement noise are used to test the effectiveness of proposed identification technique.
暂无评论