A. De Leo

Experimental Investigation of Electromagnetic Obstacle Detection for Visually Impaired Users: A Comparison With Ultrasonic Sensing

The use of electromagnetic (EM) fields for obstacle detection to aid mobility of visually impaired people is presented in this paper. The method proposed is based on the launch of EM pulses and on the measurement of the reflected signal which explores a region in front of the user of about 3 m. A laboratory system is set up, its performances (detecting the presence and the distance of obstacles) are investigated, and the measurements are compared with the data measured by an ultrasonic obstacle detection system. Results show that, with the EM system, all the obstacles tested (up to a minimum size of 3 cm × 3 cm, at a distance of 3 m) are correctly detected, as well as some specific targets (a chain, a pole, etc.) that are not visible by the ultrasonic system. The EM system has been tested in indoor and outdoor cluttered scenarios at the presence of real obstacles (single and multiple), and in all cases, it detects their presence with a signal-to-noise ratio ranging from 10 to 23 dB. Despite the use of a laboratory system, still not specifically designed for daily use, this paper demonstrates the possibility of adopting EM held pulses for obstacle detection, highlighting advantages with respect to ultrasonic systems and addressing future research activity to design an improved ad hoc EM system.

Electromagnetic travel aids for visually impaired users

This paper describes the development of an electromagnetic travel aid aiming to the improvement of the mobility of blind and visually impaired subjects in unknown environments. The paper reports the preliminary results obtained with a portable prototype. They show the feasibility of the electromagnetic “cane”, the possibility to detect the presence of obstacles not detected with ordinary cane and address further improvements.

Domestic monitoring of respiration and movement by an electromagnetic sensor

The aim of this paper is to investigate the capabilities of a novel electromagnetic technique designed for contactless monitoring of breathing activity in Ambient Assisted Living applications. The method is based on the transmission of a frequency sweep and the measurement of the reflection coefficient to determine the respiration rate of a subject. To date, the method is under optimization, but it has already shown interesting capabilities of calculating not only the respiration rate, but also additional features, as the position of the subject inside a room and his/her movements. After a brief mathematical description of the algorithm, some preliminary tests will be described concerning the monitoring of a human target inside a room. These first results clearly show the capability of the method to detect the subject, his breathing rate, position and physical activity. Of course further signal processing is required in order to distinguish between different types of movements and to classify them.

Multiparameter electromagnetic sensor for AAL indoor measurement of the respiration rate and position of a subject

In this paper, a new electro-magnetic sensing system for the indoor measurement of respiration rate and subject position is presented. The measurement system has been especially conceived for use in Ambient Assisted Living (AAL) applications; therefore, a specifically designed, radiation element has been designed and realized in order to be easily installed at home. The measurement principle is based on the measurement of the reflection coefficient S11 which is operated when a frequency sweep signal is transmitted by the radiation element placed in front of the subject. S11 values are related to the distance from the reflecting object (the subject) and can be consequently related to his/her respiration activity and position. A mathematical description of the algorithm for the extraction of the aimed information, the experimental set-up and some results, obtained in a real scenario (private apartment), are reported. These results clearly show the ability of the proposed sensing system to detect the presence of the subject, to measure the respiration rate and to determine his/her position within the observed environment. The proposed solution presents therefore most of the required features in order to be used for home monitoring and AAL applications.

The electromagnetic technology for safe mobility of visually impaired people

The aim of this paper is to present a survey of the activities carried out by the University Politecnica delle Marche concerning the safe mobility of visually impaired people in order to involve the control and automation community and present some hints for discussion. For this purpose, this contribution reports and discusses the use of electromagnetic (EM) systems as assistive technologies for mobility tasks of blind subjects also highlighting their advantages with respect to existing traditional electronic travel aids, in terms of performances, miniaturization, and wear ability. In particular, two applications of EM technologies will be discussed more in detail: a first example consists in the design and realization of a laboratory prototype of an EM sensor, able to detect the presence of obstacles, aimed to help visually impaired users during mobility tasks, possibly allowing them to walk safely and independently. The second example is the theoretical and experimental study of feasibility of an EM system, specifically addressed to visually impaired runners. Finally, some clues for discussion will be presented; the user interaction with the sensing system, the signal analysis and possible features extraction will be reviewed addressing issues requiring a multidisciplinary approach.

Design and realization of a wideband antenna for non-contact respiration monitoring in AAL application

This contribution is part of a wider research project whose final aim is the realization of a small EM sensing system for non-contact monitoring of respiration activity in indoor environments. The paper presents the design of an optimized radiating element that satisfies challenging requirements: good impedance matching over a wide frequency bandwidth (3-5 GHz), directive radiation pattern, small dimensions (in order to reduce its invasiveness) and low cost for realization. In detail, an antenna model already existing in literature has been optimized and adapted to this specific application using a full wave numerical simulator. Finally a first antenna prototype has been realized and experimentally tested to compare the measured parameters with the simulated results.

Ambient assisted living electromagnetic sensor for continuous breathing monitoring applied to movement analysis: a preliminary study

The aim of this paper is to investigate the capabilities of a novel electromagnetic technique designed for contactless monitoring of breathing activity in Ambient Assisted Living applications. The method is based on the transmission of a frequency sweep and the measurement of the reflection coefficient to determine the respiration rate of a subject. To date, the method is under optimization, but it has already shown interesting capabilities for calculating not only the respiration rate, but also additional features, as the position of the subject inside a room and his/her movements. After a brief mathematical introduction of the algorithm, some preliminary tests are presented concerning the monitoring of a human target inside a room. These first results clearly show the capability of the method to detect the subject, his breathing rate, position and physical activity. Of course further signal processing is required in order to distinguish between different types of movements and to classify them.

Theoretical Model for Remote Heartbeat Detection Using Radiofrequency Waves

Recently there is an increasing demand for contactless and unobtrusive techniques able to ensure a complete, comfortable and unobtrusive monitoring of human vital signs even in critical situations, such as burn victims and newly born infants, or when a long time monitoring is needed. This paper describes a preliminary theoretical investigation about the possibility of using an electromagnetic approach, already successfully tested for respiration monitoring, to detect the heart activity of a human subject in indoor environments. In particular, the electromagnetic model presented has been implemented to investigate the physical mechanism of interaction between the heart movement and an electromagnetic wave impinging on the human chest and to find out what is possible to observe from the outside without any electrodes.

Analytical prediction of common mode noise in a source stirred reverberation chamber

A multiple antenna source stirring technique is analytically studied and adopted to compute the common mode voltage induced across a cable terminal impedance. Sixty-two monopoles are distributed on the chamber walls. Chamber realizations are enhanced by feeding two antennas at a time so achieving a total of 1891 combinations. A cable loaded by a common mode impedance is inserted as device under test (DUT) inside the chamber. Both high frequency and low frequency cases are considered comparing the maximum values of the induced common mode voltage. In the model, all mutual coupling among the transmitting antennas and the DUT are accounted for. In the lower frequency range, undermoded condition, the technique takes benefit from the adoption of an out-of-phase feeding of each active couple of antennas. The electric field direction can be forced by a proper choice of the two active antennas.

Electromagnetic Technologies as Travel Aids for Visually Impaired Subjects

The aim of this paper is to present the electromagnetic (EM) technology as possible assistive technology for the mobility tasks of visually impaired subjects. The paper will present their characteristics, discussing pros and cons of their use with respect to the existing traditional technologies and electronic travel aids, in terms of performances, miniaturization and wearing comfort. In particular, two applications of EM technologies will be presented more in detail: a first example consists in the design and realization of a laboratory prototype of an EM system able to detect the presence of obstacles along the walking path of visually impaired users and hence to assist them during their mobility tasks, possibly allowing them to walk safely and independently. The second example is the theoretical and experimental study of feasibility of an EM system specifically addressed to visually impaired runners. In conclusion, some hints for discussion will be presented; the user interaction with the sensing system, the signal analysis and possible features extraction will be reviewed addressing issues requiring a multidisciplinary approach.