Papers by Roberto Rinaldo
Dual channel Electrodermal activity sensor for motion artifact removal in car drivers’ stress detection
2019 IEEE Sensors Applications Symposium (SAS), 2019
In this paper we present a dual channel sensor for electrodermal activity measurement, with parti... more In this paper we present a dual channel sensor for electrodermal activity measurement, with particular attention to the drivers’ stress detection. The sensor captures the elec-trodermal signals that are present on the hands of the driver, transmits them via WiFi to a laptop and then the data are processed. In particular, we developed a novel algorithm for the removal of motion artifacts that arise when the driver moves the hands on the steering wheel. We performed several kinds of tests: first in laboratory, then on a professional driving simulator and finally in a real car in city traffic. The algorithm has been compared to several well known algorithms for signal separation. We identified, as an indicator of performances, the spectral flatness of the outputs. In this application, the proposed method outperformed the benchmark algorithms.
Positioning Indoors with LTE Communications Signals of Different Bandwidth
2019 International Conference on Indoor Positioning and Indoor Navigation (IPIN), 2019
This paper describes the use of standard LTE communications signals to perform positioning indoor... more This paper describes the use of standard LTE communications signals to perform positioning indoors, despite the difficult propagation conditions in such environments that require a number of strong signals and a wide measurement bandwidth. Experiments show that the CRS transmissions embedded in normal LTE downlink signals from multiple network operators’ base stations can together be used to perform horizontal localization indoors around a building, with an accuracy of around 15m for full bandwidth LTE signals. A reference unit (LMU) is required. Alternatively and with more reference measurement units, 3D positioning can be performed using the uplink signals transmitted by the target LTE modem, and it is shown that a set of DM-RS transmissions embedded within normal uplink communications traffic to its base station can be combined to also give measurements of signals with a wide effective bandwidth.
Stress Detection Through Electrodermal Activity (EDA) and Electrocardiogram (ECG) Analysis in Car Drivers
2019 27th European Signal Processing Conference (EUSIPCO), 2019
The stress in a driver, happening during unforeseen events or taxing situations, is linked to a s... more The stress in a driver, happening during unforeseen events or taxing situations, is linked to a subject’s sympathetic system response. We present a system which detects the stress presence in car drivers through the analysis of an endosomatic Electrodermal Activity (EDA) signal, namely, Skin Potential Response (SPR), coupled with the analysis of the Electrocardiogram (ECG) signal. To log these signals we utilize a device which records the SPR from each hand of the driver, and the ECG from the chest. In the case of the SPR signal, since the hands movement injects motion artifacts, we also utilize an algorithm that dynamically selects the smoother signal coming from the two hands, and is thus able to output a clean SPR signal. Statistical features are then derived from the ECG and SPR signals, allowing their classification using a Supervised Machine Learning Algorithm. Various subjects were tested in an environment set in a company which develops professional driving simulators, both in hardware and software, and consisted in a motorized platform, a cockpit and a 180° projection screen. The test encompassed driving through a highway, with some unforeseen events happening at some positions. In the end we get a Balanced Accuracy in stress detection of 77.59 % for the considered events.
Spike Detection in EEG by a Multiresolution Approach
LTE Uplink TOA Opportunistic Measurement Based on DM-RS
This paper studies the possibility of performing radio localization by measuring the time-differe... more This paper studies the possibility of performing radio localization by measuring the time-difference-of-arrival (UTDOA) using the uplink demodulation reference signal (DM-RS) in 4G Long Term Evolution (LTE) cellular networks. The main problem of the Global Navigation Satellite System (GNSS) is the poor performance in indoor and urban canyon environments, which suffer from high signal attenuation and severe multipath propagation. With the increase of services based on the accurate location of the user, new techniques that cooperate with GNSS are necessary. The current release of the 3rd Generation Partnership Project (3GPP) LTE specification supports a UTDOA localization technique based on the Sounding Reference Signal (SRS). A Local Measurement Unit (LMU) uses knowledge of the SRS to perform the time difference measure. In this paper, an UTDOA technique that uses the DM-RS is proposed. We point out the advantages of our proposal and evaluate its feasibility by means of simulations.
Identificazione di eventi negli EEG
Multi-view videogrammetry for the measurement of plate flexural vibration
Journal of Physics: Conference Series, 2021
This paper describes a simulation study of the measurement of the flexural deflection of a thin p... more This paper describes a simulation study of the measurement of the flexural deflection of a thin plate, excited by a transverse force at the fundamental frequency of the resonance modes, using an optical system consisting of multiple cameras. The estimate of the amplitude of the vibration is obtained starting from two or more sequences of images taken by the cameras, by means of triangulation. In this paper, we assume that the system is calibrated, and we focus on the error resulting from pixellisation. The simplified optical model is used to simulate how the accuracy of the measurements varies with respect to: the distance of the cameras from the structure; the opening angle between pairs of cameras; the resolution of the cameras and their number. The aim of the work is to evaluate the influence of the cameras arrangement on the measurement quality, and in particular if the use of a number greater than 2 cameras can allow a reduction of the measurement error, allowing a favorable compromise between spatial and temporal resolution of the cameras. As an example, the average error of the reconstruction of the first flexural deflection shape falls from 12% to 4%, when the measurement setup passes from 2 cameras to 12 cameras in the considered setup.
Structural vibration measurement with multiple synchronous cameras
Mechanical Systems and Signal Processing, 2021
Abstract This paper presents a simulation and experimental study on the measurement with multiple... more Abstract This paper presents a simulation and experimental study on the measurement with multiple, i.e. more than 2, synchronous cameras of the flexural deflection shape of a beam excited by a transverse force at the fundamental resonance frequency, which gives a good estimate of the first flexural natural mode shape. The first part of the paper presents the simplified optical model employed to simulate how the accuracy of the measurements varies with respect to: a) the distance of the cameras from the structure; b) the opening angle between pairs of cameras, which is analysed with respect to the azimuthal and elevation spherical coordinates, c) the resolution of cameras and d) the number of cameras. The second part of the paper provides experimental results taken on a beam rig and camera setup assembled using off-the-shelf devices. The study shows that the accuracy of the measurements significantly rises as the setup is equipped with an increasingly larger number of cameras, which should be arranged close to the vibrating structure with large opening angles between pairs of cameras characterized by large azimuthal and small elevation spherical coordinates. For instance, the average error of the measured flexural deflection shape falls from 15% to 3% when a setup with cameras arranged along a circumference oriented parallel the beam surface, with a small offset from the beam, passes from 2 cameras to 12 cameras.
Analysis of some simple stabilizers for physically obfuscated keys
International Journal of Information Security, 2019
Physically Obfuscated Keys (POK) are used to embed in chips secret bit-strings to be used in cryp... more Physically Obfuscated Keys (POK) are used to embed in chips secret bit-strings to be used in cryptographic protocols. Usually a POK is built as an array of elementary 1-bit POKs (cells). In order to guarantee that the same secret bit-string is generated at every turn-on, stabilizer circuits are required, which are typically based on possibly expensive error-correction circuitry. In this paper we propose a stabilizer scheme that is not based on error-correction codes, but rather forces to zero the cells that are too unreliable and compensate for the disabled cells by means of a mixing stage.
Matched Filtering for Heart Rate Estimation on Compressive Sensing ECG Measurements
IEEE Transactions on Biomedical Engineering, 2017
Compressive sensing (CS) has recently been applied as a low-complexity compression framework for ... more Compressive sensing (CS) has recently been applied as a low-complexity compression framework for long-term monitoring of electrocardiogram (ECG) signals using wireless body sensor networks. Long-term recording of ECG signals can be useful for diagnostic purposes and to monitor the evolution of several widespread diseases. In particular, beat-to-beat intervals provide important clinical information, and these can be derived from the ECG signal by computing the distance between QRS complexes (R-peaks). Numerous methods for R-peak detection are available for uncompressed ECG. However, in the case of compressed sensed data, signal reconstruction can be performed with relatively complex optimization algorithms, which may require significant energy consumption. This paper addresses the problem of heart rate estimation from CS ECG recordings, avoiding the reconstruction of the entire signal. We consider a framework, where the ECG signals are represented under the form of CS linear measurements. The QRS locations are estimated in the compressed domain by computing the correlation of the compressed ECG and a known QRS template. Experiments on actual ECG signals show that our novel solution is competitive with methods applied to the reconstructed signals. Avoiding the reconstruction procedure, the proposed method proves to be very convenient for real-time low-power applications.
Making random permutations from physically unclonable constants
International Journal of Information Security, 2016
The recent availability of reliable schemes for physically unclonable constants (PUC) opens inter... more The recent availability of reliable schemes for physically unclonable constants (PUC) opens interesting possibilities in the field of security. In this paper, we explore the possibility of using PUCs to embed in a chip random permutations to be used, for example, as building blocks in cryptographic constructions such as sponge functions, substitution–permutation networks, and so on. We show that the most difficult part is the generation of random integers using as the only randomness source the bit-string produced by the PUC. In order to solve the integer generation problem, we propose a partial rejection method that allows the designer to trade-off between entropy and efficiency. The results show that the proposed schemes can be implemented with reasonable complexity.
Separation and Analysis of Fetal-ECG Signals From Compressed Sensed Abdominal ECG Recordings
IEEE Transactions on Biomedical Engineering, 2016
Analysis of fetal electrocardiogram (f- ECG) waveforms, as well as fetal heart-rate (fHR) evaluat... more Analysis of fetal electrocardiogram (f- ECG) waveforms, as well as fetal heart-rate (fHR) evaluation, provide important information about the condition of the fetus during pregnancy. A continuous monitoring of f-ECG, for example using the technologies already applied for adults ECG tele-monitoring (e.g., Wireless Body Sensor Networks, WBSNs), may increase early detection of fetal arrhythmias. In this work, we propose a novel framework, based on Compressive Sensing (CS) theory, for the compression and joint detection/classification of mother and fetal heart beats. Our scheme is based on the sparse representation of the components derived from Independent Component Analysis (ICA), which we propose to apply directly in the compressed domain. Detection and classification is based on the activated atoms in a specifically designed reconstruction dictionary. Validation of the proposed compression and detection framework has been done on two publicly available datasets, showing promising results (sensitivity S=92.5%, P+=92%, F1=92.2% for the Silesia dataset and S=78%, P+=77%, F1=77.5% for the Challenge dataset A, with average reconstruction quality PRD=8.5% and PRD=7.5%, respectively). The experiments confirm that the proposed framework may be used for compression of abdominal f-ECG and to obtain real time information of the fetal heart rate, providing a suitable solution for real-time, very low power f-ECG monitoring. To the authors' knowledge, this is the first time that a framework for the low-power CS compression of fetal abdominal ECG is proposed combined with a beat detector for fHR estimation.
2005 Digest of Technical Papers. International Conference on Consumer Electronics, 2005. ICCE., 2005
We propose a robust and scalable transmission scheme based on Multiple Description (MD) coding. E... more We propose a robust and scalable transmission scheme based on Multiple Description (MD) coding. Each description is encoded using a standard video codec such as MPEG-2 or H.264. This scheme provides equal or better robustness with respect to other solutions such as Forward Error Correction (FEC), at lower system complexity; also, it provides scalability by selectively dropping descriptions. 1
Video streaming over lossy/variable bandwidth . networks by means of multiple description
IEEE 6th Workshop on Multimedia Signal Processing, 2004.
In this paper we propose a system based on Multiple Description coding (MD) to stream video over ... more In this paper we propose a system based on Multiple Description coding (MD) to stream video over lossy or variable bandwidth networks. MD coding can be integrated in several ways into existing state-of-the-art video codecs, as MPEG or the new H.264. The proposed scheme ...
Media-agnostic congestion control in peer-to-peer multimedia streaming networks
2012 5th International Symposium on Communications, Control and Signal Processing, 2012
Rate control for multimedia streaming has been the subject of many recent research activities. In... more Rate control for multimedia streaming has been the subject of many recent research activities. In this paper we propose a simple, but optimal technique for rate control that does not require the knowledge of the type of the multimedia data, but only needs that every packet is labeled with a “priority value” that represents the relative importance of the packet. This makes it possible to implement the proposed technique at the transport level, nicely separated from the application level.
Comparison of lossy to lossless compression techniques for digital cinema
2004 International Conference on Image Processing, 2004. ICIP '04.
Abstract This paper presents the investigation carried out for the MetaVision project in the area... more Abstract This paper presents the investigation carried out for the MetaVision project in the area of lossless compression for digital cinema. The goal of this investigation was to identify, among the many approaches, the one that is most suited to the MetaVision requirements. An extensive simulation campaign has thus identified JPEG-2000 as the best compromise between efficiency, standardization and lossy-to-lossless performance. This result was hardly predictable, especially because of the peculiar kind of material to be coded.
Relations between thek-dimensional unconstrained and linear phase FIR Wiener filters
Multidimensional Systems and Signal Processing, 1995
In this note, we show that thek-dimensional linear phase FIR Wiener filter can be obtained from t... more In this note, we show that thek-dimensional linear phase FIR Wiener filter can be obtained from the unconstrained filter with a simple “reverse and add” operation. The relation between the linear phase and unconstrained phase filters is obtained also in the case of a multichannelk-dimensional system. In this case, the properties of the autocorrelation matrix do not allow the simplifications noted for the single channel case.
Demystifying Lie Group Methods for Signal Processing: A Tutorial
IEEE Signal Processing Magazine, 2021
Many problems in signal processing [e.g., filter bank design, independent component analysis (ICA... more Many problems in signal processing [e.g., filter bank design, independent component analysis (ICA), beamforming design, and neural network training] can be formulated as optimization over groups of transformations that depend continuously on real parameters (Lie groups). Such problems are usually tackled in two ways: using a constrained optimization procedure or using some parameterization to transform them into unconstrained problems.
Indoor Path Loss Statistical Characterization and Modeling for the Broad VHF–UHF Band
IEEE Antennas and Wireless Propagation Letters, 2020
In this letter, an investigation of the very high frequency–ultrahigh frequency (VHF–UHF) wireles... more In this letter, an investigation of the very high frequency–ultrahigh frequency (VHF–UHF) wireless broadband indoor channel is carried out. In particular, a wireless channel measurement campaign in an indoor environment has been made, in order to characterize the path loss in a broad set of frequencies. The wireless channel is sounded by using a set of discone wideband antennas and a vector network analyzer set to sweep the transmitted signal in the considered band. The measurement results lead to the derivation of a well specified indoor path loss exponent statistical model that takes into account the frequency dependence as well as the distance between the antennas. Three different statistical model refinements are presented, and each of them shows an enhanced ability to predict the path loss.
In this paper we consider the deployment of impulse modulation for powerline multiuser communicat... more In this paper we consider the deployment of impulse modulation for powerline multiuser communications combined with either time hopping, or direct sequence CDMA. We focus on the synchronization and channel estimation problem in the presence of multipath propagation and impulse noise.
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Papers by Roberto Rinaldo