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. 2020 Mar 12;20(6):1574.
doi: 10.3390/s20061574.

UWB/BLE Tracking System for Elderly People Monitoring

Jerzy Kolakowski  1 , Vitomir Djaja-Josko  1 , Marcin Kolakowski  1 , Katarzyna Broczek  2
Affiliations

UWB/BLE Tracking System for Elderly People Monitoring

Jerzy Kolakowski et al. Sensors (Basel). .

Abstract

Localization systems are the source of data that allows to evaluate elderly person's behaviour, to draw conclusions concerning his or her health status and wellbeing, and to detect emergency situations. The article contains a description of a system intended for elderly people tracking. Two novel solutions have been implemented in the system: a hybrid localization algorithm and a method for wireless anchor nodes synchronization. The algorithm fuses results of time difference of arrival and received signal strength measurements in ultrawideband (UWB) and Bluetooth Low Energy (BLE) radio interfaces, respectively. The system allows to change the intensity of UWB packets transmission to adapt localization accuracy and energy usage to current needs and applications. In order to simplify the system installation, communication between elements of the system infrastructure instead of wire interfaces is performed over wireless ones. The new wireless synchronization method proposed in the article consists in retransmission of UWB synchronization packets by selected anchor nodes. It allows for extension of the system coverage, which is limited by the short range of UWB transmission. The proposed solution was experimentally verified. The synchronization method was tested in a laboratory, and the whole system's performance was investigated in a typical flat. Exemplary results of the tests performed with older adult participation in their own homes are also included.

Keywords: AAL; localization systems; tracking algorithms.

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Conflict of interest statement

The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

Figures

Figure 1
Figure 1
Localization system functional architecture.
Figure 2
Figure 2
Localization system devices: the tag and the anchor node.
Figure 3
Figure 3
Data transmitted between system devices: a tag, an anchor, and a system controller.
Figure 4
Figure 4
Transmission between the particular parts of the infrastructure during wireless synchronization procedure.
Figure 5
Figure 5
Transmission scheme in the proposed wireless synchronization procedure.
Figure 6
Figure 6
Test setup for the synchronization method investigation.
Figure 7
Figure 7
Empirical cumulative distribution functions of the TDOA errors for different synchronization options.
Figure 8
Figure 8
Difference between atmospheric pressure measured by the tag and the anchor, while moving one floor down and up.
Figure 9
Figure 9
System layout during accuracy and precision tests: green shaded areas represent furniture: (a) location of test points, (b) reference movement trajectory
Figure 10
Figure 10
Results of static tag localization using hybrid algorithm with one ultrawideband (UWB) packet transmitted every two seconds.
Figure 11
Figure 11
Empirical cumulative distribution functions of (a) localization error and (b) circular error probability (CEP) for 50% of the results.
Figure 12
Figure 12
Localization of a moving person results.
Figure 13
Figure 13
Empirical cumulative distribution function for trajectory error.
Figure 14
Figure 14
Current consumption during two seconds of the tag’s operation.
Figure 15
Figure 15
Current consumption during sending of (a) a Bluetooth Low Energy (BLE) packet and (b) a UWB packet.
Figure 16
Figure 16
Maps illustrating occupancy of the house areas during three selected days (Day 1–3) of the experiment.
Figure 17
Figure 17
Number of steps taken by the older person during three selected days (Day 1–3) of the experiment.
See this image and copyright information in PMC

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