Publicaties

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Applying polynomial decoupling methods to the polynomial NARX model Vrije Universiteit Brussel

Kiana Karami, David Westwick, Joannes Schoukens
System identification uses measurements of a dynamic system’s input and output to reconstruct a mathematical model for that system. These can be mechanical, electrical, physiological, among others. Since most of the systems around us exhibit some form of nonlinearbehavior, nonlinear system identification techniques are the tools that will help us gain abetter understanding of our surroundings and potentially let us improve their performance. One ...

User-friendly nonlinear nonparametric estimation framework for vibro-acoustic industrial measurements with multiple inputs Vrije Universiteit Brussel

Péter Zoltán Csurcsia, Bart Peeters, Joannes Schoukens

This paper introduces a user-friendly estimation framework for industrial measurements of vibro-acoustic systems with multiple inputs. Many mechanical structures are inherently nonlinear and there is no unique solution for modeling nonlinear systems. This is especially true when multiple-input, multiple-output (MIMO) systems are considered. This paper addresses the questions related to the user-friendly semi-automatic processing of MIMO ...

A1.5-bit DFT Analyzer Vrije Universiteit Brussel

Paolo Carbone, Joannes Schoukens, Alessio De Angelis, Antonio Moschitta
In this article, it is shown how to estimate thefrequency response function of a linear system using a three-leveldigital-to-analog converter (DAC) and a 1-bit analog-to-digitalconverter (ADC). Estimation requires the usage of a three-levelperiodic stimulus signal and a sinewave, used as a dither signalto improve the effective resolution of the 1-bit ADC. By asuitable choice of the source sequence, ...

Estimating a nonparametric data-driven model of the lift on a pitching wing Vrije Universiteit Brussel

Muhammad Faheem Siddiqui, Péter Zoltán Csurcsia, Jan Rik Decuyper, Tim De Troyer, Joannes Schoukens, Mark Runacres

In aerodynamics, as in many engineering applications, a parametrised mathematical model is used for design and control. Often, such models are directly estimated from experimental data. However, in some cases, it is better to first identify a so-called nonparametric model, before moving to a parametric model. Especially when nonlinear effects are present, a lot of information can be gained from the nonparametric model and the resulting ...

A nonlinear model of vortex-induced forces on an oscillating cylinder in a fluid flow Vrije Universiteit Brussel

Jan Rik Decuyper, Tim De Troyer, Koen Tiels, Joannes Schoukens, Mark Runacres

A nonlinear model relating the imposed motion of a circular cylinder, submerged in a fluid flow, to the transverse force coefficient is presented. The nonlinear fluid system, featuring vortex shedding patterns, limit cycle oscillations and synchronisation, is studied both for swept sine and multisine excitation. A nonparametric nonlinear distortion analysis (FAST) is used to distinguish odd from even nonlinear behaviour. The information which ...

Frequency and Amplitude Domain DAC-ADC Co-Testing Using Ternary Signals Vrije Universiteit Brussel

Paolo Carbone, Joannes Schoukens, Alessio De Angelis, Antonio Moschitta
The parametric estimation of devices in a signal chain, including the cascade of a digital-to-analog converter (DAC), a low-pass filter, and an analog-to-digital converter (ADC), is considered in this article. Frequency- and amplitude-domain procedures are presented for the estimation of the DAC output levels and ADC transition levels connected in a loopback configuration, including a low-pass filter in-between. A special class of source signals ...

Frequency Response Measurements With Local Parametric Modeling Vrije Universiteit Brussel

Dieter Toon M Verbeke, Joannes Schoukens
The concept of local parametric modeling has drawn renewed attention to frequency response function (FRF) measurements. Essentially, these approaches assume a particular parametric structure and approximate the FRF and the leakage errors in a small-frequency band around the frequency of interest. Following the successful application of the idea in the local polynomial method (LPM), the local rational method (LRM) was developed, replacing ...

Extending the Best Linear Approximation Framework to the Process Noise Case Vrije Universiteit Brussel

Maarten Schoukens, Rik Pintelon, Tadeusz Dobrowiecki, Joannes Schoukens
The best linear approximation (BLA) framework has already proven to be a valuable tool to analyze nonlinear systems and to start the nonlinear modeling process. The existing BLA framework is limited to systems with additive (colored) noise at the output. Such a noise framework is a simplified representation of reality. Process noise can play an important role in many real-life applications. This paper generalizes the best linear approximation ...

Quick Estimation of Periodic Signal Parameters From 1-Bit Measurements Vrije Universiteit Brussel

Paolo Carbone, Joannes Schoukens, Antonio Moschitta
Estimation of periodic signals, based on quantized data, is a topic of general interest in the area of instrumentation and measurement. Although several methods are available, new applications require low-power, low-complexity, and adequate estimation accuracy. In this paper, we consider the simplest possible quantization, that is, binary quantization, and describe a technique to estimate the parameters of a sampled periodic signal, using a fast ...