A Radar-Based Smart Sensor for Unobtrusive Elderly Monitoring in Ambient Assisted Living Applications

Abstract

Continuous in-home monitoring of older adults living alone aims to improve their quality of life and independence, by detecting early signs of illness and functional decline or emergency conditions. To meet requirements for technology acceptance by seniors (unobtrusiveness, non-intrusiveness, and privacy-preservation), this study presents and discusses a new smart sensor system for the detection of abnormalities during daily activities, based on ultra-wideband radar providing rich, not privacy-sensitive, information useful for sensing both cardiorespiratory and body movements, regardless of ambient lighting conditions and physical obstructions (through-wall sensing). The radar sensing is a very promising technology, enabling the measurement of vital signs and body movements at a distance, and thus meeting both requirements of unobtrusiveness and accuracy. In particular, impulse-radio ultra-wideband radar has attracted considerable attention in recent years thanks to many properties that make it useful for assisted living purposes. The proposed sensing system, evaluated in meaningful assisted living scenarios by involving 30 participants, exhibited the ability to detect vital signs, to discriminate among dangerous situations and activities of daily living, and to accommodate individual physical characteristics and habits. The reported results show that vital signs can be detected also while carrying out daily activities or after a fall event (post-fall phase), with accuracy varying according to the level of movements, reaching up to 95% and 91% in detecting respiration and heart rates, respectively. Similarly, good results were achieved in fall detection by using the micro-motion signature and unsupervised learning, with sensitivity and specificity greater than 97% and 90%, respectively.

Determining the Position of the Moving Personsin 3D Space by UWB Sensors using Taylor Series Based Localization Method

“…The group of the linear equations written in the matrix form (7) is repeatedly solved by the least-squares method at each iteration to refind a new estimate of the target coordinates denoted as Tn = (xn, yn, zn) by equation (8). For the updated estimate of the person position its new coordinates are refined according to T n x n y n z n δ δ δ δ    express a localization error in the nth iteration.…”

“…For the updated estimate of the person position its new coordinates are refined according to T n x n y n z n δ δ δ δ    express a localization error in the nth iteration. It is obtained as the least-squares solution of (7) by (8). Here, it is used to control the iteration process of solution (2) as follows: δδ   and n δε  , the iterating process is convergent.…”

“…by using the least-square algorithm, the least-square solution of δ estimations of the target coordinates [x0 y0 z0] T , the unknown values of location errors δ can be determined by(8). Then the estimations of the target coordinates are updated according to the expression the target coordinates [x0 y0 z0] T according to(9) is repeated until δ is sufficiently small, i.e.…”

Unobtrusive Sensing for Home-Based Post-Stroke Rehabilitation

“…This includes a proposed cost-effective integrated Radar system which can operate at millimetre wave frequencies. Diraco et al, (2017) discussed home-based monitoring of elderly patients using a Radar-based smart sensor to detect abnormalities in ADLs. This was based on the information provided by an ultrawideband Radar sensor on locomotive and the cardiorespiratory functions of the body irrespective of physical obstruction and lighting conditions (Diraco et al, 2017).…”

3D Printed Radar Lenses with Anti-Reflective Structures

“…The research, development and application of radar with respect to the consumer market has greatly expanded over the last 10 years [1]. This is a step change from radar traditionally being a costly technology area best suited to military, aerospace, nautical and scientific measurement areas to now being applied, more and more, to autonomous vehicles [2], smart cities [3] and personal health monitoring devices [4]. Radar is now a key technology for these areas, and the maximization of signal strength is paramount to the correct and optimal operation of devices, with sub-optimal operation potentially resulting in incorrect measurement, mis-information and safety failures.…”