## Overview Research Topics

The long term objective of the department is the realization of the IMMI project (Interpretation by Measuring, Modelling and Identification), since 1989. Beside this main project, which covers a broad spectrum of several related activities, also some other independent research topics are at stake.

### Decoupling noisy multivariate polynomials in nonlinear system identification

In the field of system identification, one special type of nonlinear models are the so-called block-oriented models, and more specifically the Wiener-Hammerstein models. When identifying parallel Wiener-Hammer-stein systems, a multiple-input-multiple-output polynomial should be decoupled, that...

### Identifying parallel Wiener-Hammerstein systems by decomposing Volterra kernels

To capture the nonlinear effects of the real world, the focus of system identification is shifting from linear to nonlinear dynamical models. Every nonlinear dynamic system with fading memory can be approximated with arbitrary precision by its Volterra kernel description, which generalizes the...

### BLA-based Design and Analysis of VCO-based Sigma-Delta Modulator

Nonlinear system theory is involved. The available theoretical frameworks depend on the assumed system properties and the applied signals. An example is the Volterra theory framework which uses a series expansion of the system’s behaviour around an operating point. This operating point can be...

### Measuring nonlinear distortions: from test case to an F-16 Fighter

What are the similarities and differences between the behavior of a small vibrating test system and an F-16 fighter? To find it out, we compare measurements of the test system to measurements from the bolted connection of the wing and the missile of a F-16 Fighter Falcon from the Belgian air...

### Identification methods for low-power sensors

The Internet of Things (IoT) will soon result in a huge number of smart devices with actuators, sensors, network connectivity and signal processing. The scientific objective is to extend the current state-of-the-art frequency identification methods to enable their use within low-cost, low power...

### Linear parameter-varying modeling and decentralized fault diagnosis for large sets of interacting subsystem

Fault Detection and Isolation (FDI) systems aim at the early detection and localization of faults. They are the key for the establishment of condition-based maintenance on industrial processes, which allows for cost reduction, and a safer and more reliable operation. The research on FDI has been...

### Frequency Response Matrix Estimation From Partially Missing Data – for Periodic Inputs

Time-variant dynamics are present in quite some engineering applications. Think of, for example, pit corrosion of metals where the time-variation is induced by the changing surface; thermal drift in power electronics and lithium-ion batteries whose characteristics are temperature and charge...

### Data driven fast measurements

Measurement techniques have fundamental speed and accuracy limitations. The speed and precision of a measurement device used in monitoring and control tasks determines the quality of the available data, which in turn limits the accuracy of models derived from the data. In this project, we...

### Identification of multiple reflections in high frequency structures

Necessity of identifying reflections is not only an interest for engineers working at high frequencies. Engineers from other societies such as geophysics, mine-field detections and civil engineering are also concerned about the reflections. While in these fields mainly identifying the positions...

### Integration of the Linear Parameter-Varying framework in the design of supply modulated high frequent power amplifiers

Modern power amplifier designs attempt to trade off the power efficiency and the nonlinear distortion of the amplifier. This leads to complex amplifier structures, such as supply modulated amplifies, where the drain supply of the transistor device is modulated in function of the envelope of the...

### Model driven design of high performance microwave filters

Microwave filters are steadily evolving towards the use of more complex transmission line structures as building blocks. This is needed to cope with the highly demanding specifications of modern telecommunication equipment.

### Estimation of respiratory impedance at low frequencies using the forced oscillation technique

The forced oscillation technique (FOT) is a non-invasive measurement technique to characterize the impedance of a respiratory system (Zrs). Zrs is defined as a frequency dependent ratio of pressure at the airway opening (pao) to air flow (qe) induced by Zrs.

### Decoupling Multivariate Nonlinearities in System Identification

Nonlinear system identification often makes use of coupled multiple-input-multiple-output static nonlinear functions to represent nonlinearities [5, 6]. For the sake of model interpretability and to limit the rapid increase of parameters it is desirable to find a parsimonious description. A...