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「世大智科/天才家居」-我們創業囉
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Authors: C.-Y. Huang, K.-W. Chang, C.-Y. Tai, W.-T. Chen, Y.-L. Hsu (2017-06-12); recommended Yeh-Liang Hsu (2017-08-14).
Note: This paper was published in 2017 IEEE International Conference on Consumer Electronics - Taiwan (ICCE-TW).

Development of a smart living platform based on a motion sensing carpet

ABSTRACT

Localization and mobility monitoring are fundamental functions for constructing a smart living space. This paper presents a smart living platform based on motion sensing carpets. It is developed in the form of 50×50cm ‘puzzle floor mat’ units, which allows the users to assemble by themselves according to their desired shape and area. From the pressure data collected by motion sensing carpets, functions such as location tracking, mobility monitoring and fall detection can be achieved. This platform has been installed in Zhulun Apartment for field trial.

INTRODUCTION

Changes in mobility level for older adults are highly related to the transition from relatively independent living to ill and declined functional health status [1][2]. In addition, wandering behavior is significantly more prevalent in patients with dementia. It is important to provide objective and accurate approaches for localization, walking trajectory and long-term mobility level assessment in the elderly care environment. Considering user acceptance, the technology in elderly care environment has to be unobtrusive, easy to use, low cost, considerate for privacy and be a natural part of the home environment [3]. As a result, the floor sensor is a more suitable approach than cameras and wearable devices. This paper presents the development and implementation of WhizCarpet, a motion sensing carpet for tele-monitoring of indoor locations, walking trajectory, mobility level and fall events in an unobtrusive way for older adults in the elderly care environment.

METHOD

The motion sensing carpet WhizCarpet is developed in the form of 50×50cm ‘puzzle floor mat’ units, which allows the users to assemble by themselves according to their desired shape and area (Figure 1). The auto mapping firmware identifies relative positions of all units after assembly. The working principle is similar to that of a membrane switch. Once a WhizCarpet unit is under pressure, the top and bottom layers make contact with each other. Different pressure will create different contact quality and therefore generates different resistance (Figure 2). I2C bus is used for data transmission between units. The WhizCarpet is designed as an Internet of Thing (IoT) device and follows the Message Queuing Telemetry Transport (MQTT) protocol. It collects data from sensor units, perform the analysis and publish events to the ‘‘broker’’. Other IoT devices such as mobile devices of the caregivers can receive events by subscribing specific topic, and displays the location and fall events on the App.

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Fig.1 WhizCarpet allows the users to assemble the units by themselves according to their desired shape and area

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Fig.2 Different pressure will create different contact quality and therefore generates different resistance

Information structure

WhizCarpet is designed as an IoT device. There are two possible information structures, depending on the environments. Figure 3 shows the information structure for household environment. ESP8266 is used as the controller for WhizCarpet, which collects data from sensor units and perform fundamental analysis. It is also a “publisher” in the IoT structure, which publishes “events” such as location and fall events to the Raspberry pi.

Raspberry pi is the IoT “broker” which receives events published by ESP8266, stores them and performs further analysis. In the home environment, Raspberry pi also works as a publisher, which publishes events to a cloud broker. Mobile devices subscribing the specific topic will receive notification of the events.

In hospitals and nursing homes, data is often not allowed to transmitted outside. As shown in Figure 4, in this case only mobile devices in the same intranet can subscribe specific topic and receive events notifications. Figure 5 shows the App receives and displays a possible fall event.

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Fig.3 Information structure for household environment

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Fig.4 Information architecture for Hospital and Nursing home environment

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Fig.5 App receives and displays a possible fall event

Results & Discussion

The smart living platform based on motion sensing WhizCarpet has been developed and implemented in Zhulun Apartment for healthy older adults (Figure 6). Reliability of the information structure, user acceptance, as well as other practical design issues were observed and verified in this field trial. In general, older adults seemed to like the WhizCarpet and requested to install in more rooms. Issues observed in this field trial include as follows:

Ÿ   The indicator LED light is too bright for older adults at night.

Ÿ   High friction between the chair and the WhizCarpet cause difficulties when the older adult pulls out the chair.

Ÿ   How WhizCarpet can be cleaned.

Ÿ   The pins of the connector are too easy to bend when user assembles WhizCarpet.

Ÿ   Wi-Fi signal is sometimes unstable.

Ÿ   Some data packages were lost when a large amount of data is sent at the same time, resulting in incorrect display of current status.

Ÿ   Some adjustments were made to solve these problems encountered in the field trial:

Ÿ   The color of controller box was changed to black.

Ÿ   Sponge foam caps were added to the chair legs to decrease friction.

Ÿ   WhizCarpet was designed as water repellent. The surface also receives antifouling treatment for easy maintenance.

Ÿ   The connector has been redesigned into pogo pin for easier assembly. Plastic clasp is added to make it more stable.

Ÿ   ESP8266 PCB has been redesigned to add an auto restart mode, and a stronger antenna was added.

Ÿ   ESP8266 was set to refresh the current status of WhizCarpet sensor every 20 second.

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Fig.6 WhizCarepet has been developed and implemented in Zhulun apartment

REFERENCES

[1]       Celler, B. G., Hesketh, T., Earnshaw, W., Ilsar, E. (1994). An instrumentation system for the remote monitoring of changes in functional status of the elderly at home. Proceedings of the 16th Annual International Conference of the IEEE EMBS, Vol. 2, pp. 908-909.

[2]       Kaushik A.R., Celler B.G. (2006) Characterization of Passive Infrared Sensors For Monitoring Occupancy Pattern. in 28th Annual International Conference of the IEEE Engineering in Medicine and Biology Society.

[3]       Leusmann, C. Mollering, L. Klack, Kai Kasugai, M. Ziefle, B. Rumpe (2011). Your Floor Knows Where You Are: Sensing and Acquisition of Movement Data. Proceedings of the 2011 IEEE 12th International Conference on Mobile Data Management, Vol. 2, pp. 61-66.