WO2020012144A1

WO2020012144A1 - Determining presence of a person

Info

Publication number: WO2020012144A1
Application number: PCT/GB2018/051990
Authority: WO
Inventors: Loong Yen Johann SIAU; Michael James GODFREY
Original assignee: Source to Site Accessories Limited
Priority date: 2018-07-12
Filing date: 2018-07-12
Publication date: 2020-01-16

Abstract

A system for indicating presence of a person in a region has a plurality of electrical accessories arranged around the region. Each electrical accessory comprises a wireless transmitter configured to transmit a wireless signal and a wireless receiver configured to receive a wireless signal transmitted by another electrical accessory of the plurality of electrical accessories. A processor is configured to indicate presence of the person based on the wireless signals transmitted and received between at least some of the plurality of electrical accessories.

Description

Determining Presence of a Person

Field of the Invention

The invention relates to a system for determining presence of a person (for example, the presence or location of a person in a building).

Background of the Invention

It can be useful to be able to detect and monitor the location of a person. For example, to check on the welfare of an elderly occupant and raise an alarm if they have not moved from a particular position for a significant period of time, to detect and locate intruders, or to optimise the operation of electrical devices for the location of people in a building (such as, turning lights off when nobody is in a room or in the vicinity of a light to save energy).

Passive infrared sensors are often used to trigger intruder alarms or to detect that somebody is in a room to turn on a light. However, passive infrared sensors tend to rely on detecting motion which means that they can be fooled if a person is not moving much or at all, for example, resulting in lights being turned off if somebody is sat still in a room.

The Global Positioning System (GPS) provides an accurate way of locating a person outside, but rarely works successfully indoors without the installation of dedicated indoor positioning infrastructure (such as radio beacons or lidar) and requires each person to remember to carry a mobile device to triangulate the position between the indoor positioning infrastructure and their mobile device. Systems which rely on a user remembering to carry a mobile device are inconvenient because people may forget, or decide not to carry, their mobile device.

Existing methods for monitoring the welfare of an elderly or vulnerable person require them to wear an alarm which they must activate manually when they need help, or which have a tilt switch which activates the alarm automatically when they fall over. The alarm sends a signal over a communication network to a monitoring station where an operator arranges assistance to be sent. However, these alarms usually have no way to report the specific location of the person, and they rely on the person remembering to wear the alarm, whereas elderly and vulnerable people may frequently forget or refuse to wear their alarm. It has been proposed to use an existing Wi-Fi access point in a house to locate the presence of a wireless device that is being carried by a person, by measuring the signal strength between the Wi-Fi access point and the wireless device. However, this still has the disadvantages that the person must remember to carry a wireless device for their location to be known and most houses only have one Wi-Fi access point installed meaning that it may only be possible to detect that the wireless device is in the house, but not the specific location of the wireless device within the house. Even in buildings, such as offices, with multiple Wi-Fi access points, the number and distribution of these Wi-Fi access points may be too sparse for accurate locating and a person still needs to carry a wireless device.

Cameras can be used to locate and track people, but people are understandably not keen to have all of their movements recorded on camera, particularly in their own homes.

It would, therefore, be desirable to find a way to locate people which overcomes at least some of these disadvantages.

Summary of the Invention

According to a first aspect of the invention, there is provided a system for indicating presence and/or location of a person (e.g., in a building). The system comprises a plurality of electrical accessories arranged around a region (e.g., around a building). Each electrical accessory comprises a wireless transmitter configured to transmit a wireless signal and a wireless receiver configured to receive a wireless signal transmitted by another electrical accessory of the plurality of electrical accessories. A processor is configured to indicate presence and/or location of the person based on the wireless signals transmitted and received between at least some (for example, two or more, or all) of the plurality of electrical accessories.

This system takes advantage of the fact that "smart" electrical accessories (such as smart electrical outlets and smart light switches) have a built-in wireless transceiver and will be fixed in known locations (eg, in known fixed locations around a building) to also determine the presence and/or the location of a person using the wireless signals transmitted and received by this network of "smart" electrical accessories. In this way, presence and/or location detection can be built into existing smart electrical accessories, removing the cost and complexity of installing dedicated sensors. There are no privacy issues, unlike cameras, and the presence and/or location of the person can be determined without the person having to carry any kind of mobile device or tag. The electrical accessories may include any "smart" electronic devices with a wireless transceiver capable of reporting received signal strength (RSSI). Some of the electrical accessories may be located in a known fixed locations (such as coupled to a wall, floor or ceiling of a building) and directly connected to an electrical network (for example, hardwired into a building's electrical network during construction) such as light switch and electrical sockets. Some of the electrical accessories could be plugged-in to conventional electrical sockets, to extend the system into areas without smart electrical outlets, for example. Any of the electrical accessories may include an electrical socket, an electrical switch, a light switch, a heating control, a control panel, a touch screen, a wireless access point, a device gateway, and a smoke, heat or fire detector.

A change in signal strength between the transmitted and received wireless signals over time may indicate presence of a person (eg, in the building). The processor may send a control signal to control an electrical device or an electrical accessory when presence is indicated.

A background signal strength may be recorded. The background signal strength may correspond to the signal strength between each wireless transmitter and wireless receiver in the region (such as a building) without occupants. The signal strength between some or all of the wireless transmitters and wireless receivers may be compared with the background signal strength. A difference in the signal strength between some or all of the wireless transmitters and wireless receivers and the background signal strength may indicate that a person is present in the region. A change in the difference over time may indicate that the person is moving.

Presence of the person may be determined based on the average signal strength between some or all of the wireless transmitters and wireless receivers and the average signal strength of the background signal strength. Where the difference between the average signal strength of some or all of the wireless transmitters and wireless receivers and the average signal strength of the background signal strength exceeds a threshold, this may indicate presence of a person. The threshold may be selected based on typical fluctuations in the wireless signal strength. Comparing averages in this way does not allow the precise location of the person to be determined, but provides a computationally efficient way to determine that the person is present before proceeding to the computationally more demanding step of determining the precise location of the person.

The processor may be further configured to determine a location of the person (e.g., in a building). The server may only determine the location in response to determining that the person may be present. The server determines the location of the person by comparing the signal strength between some or all of the wireless transmitters and wireless receivers with fingerprints. Each of the fingerprints comprise signal strengths between each wireless transmitter and wireless receiver for the person standing in a particular position around the region (e.g., around a building).

The processor may send a control signal to control an electrical device or an electrical accessory based on the location of the person. For example, the control signal may turn lights on/off depending on whether the user is near to the light. As the person will disturb the wireless signals transmitted and received regardless of whether or not the person is moving, unlike a passive infrared sensor the lights will not be turned off just because the person is sat still for a period of time.

Processing may take place at a central server or in a microcontroller located in one or more of the electrical accessories.

The electrical accessories may be arranged in multiple zones, such as multiple rooms of a building. Location accuracy may be improved by incorporating the wireless signals transmitted and received by more electrical accessories, even if they are separated in another zone or room and the signal is somewhat attenuated.

The invention is particularly applicable to determining the presence and/or location of a person in a building (such as a dwelling, industrial, commercial, healthcare, government or similar premises). However, the invention is also applicable to determining the presence and/or location of a person in other areas, such as an outdoor arena, sports pitch and garden.

Brief Description of the Drawings

The invention shall now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 illustrates a plan view of a building incorporating a system for determining the location of a person in the building using a plurality of smart electrical accessories; and

Figure 2 illustrates an example of a smart electrical accessory. Detailed Description

Figure 1 illustrates a building 110 with a network of smart electrical accessories such as electrical outlet 140 and light switches 150 fixed around the walls 111 of the building 110 in known locations connected to the building's electrical network. The electrical accessories are "smart" electrical accessories because they contain a wireless transceiver which allows each electrical accessory to be remotely controlled.

Figure 2 shows an example of a smart electrical accessory, in this case a smart electrical outlet 140. The smart electrical outlet 140 has a wireless transceiver 147 with a wireless transmitter 149 for sending wireless signals and a wireless receiver 148 for receiving wireless signals. The electrical outlet 140 has an electrical socket 142 for attaching an electrical device. The electrical socket 142 is connected to the mains electricity supply 141 of the building 110 via switch 144 which controls the supply of electricity to the electrical socket 142. The switch 144 is controlled by the processor 146, which can turn the switch on and off in response to instructions received from the wireless receiver 148. This allows the electrical socket 142 to be controlled remotely, for example, by an application running on a smartphone. The wireless transmitter 149 allows the electrical outlet 140 to send information, such as the on/off status of the electrical socket 142 to a smartphone. The skilled person will appreciate that other smart electrical accessories would be configured similarly, for example, in a smart light switch 150 the electrical socket 142 would simply be replaced by a direct electrical connection to a light bulb.

The invention makes use of the wireless transceiver 147 in smart electrical accessories to find out whether a person 130 is present in the building and, if they are, to find out their specific location, by examining the way the person 130 affects the strength of the wireless signal between some or all of the smart electrical accessories.

As well as employing smart electrical accessories that are hardwired into the building's electrical network, such as smart light switches 150 and smart electrical outlets 140, the smart electrical accessories could be any other smart electrical device (such as a smart TV, smart refrigerator, and Wi-Fi access point) that can be plugged into a conventional electrical outlet and can report the received signal strength from a wireless transmitter 149 on request.

As well as using the signal strength between smart electrical accessories in the same room to the room in which the person 130 is located, the signal strength between a smart electrical accessory in the same room and one in an adjacent room can be used to improve the accuracy of position determination, particularly when the room in which the person 130 is located contains few smart electrical accessories.

A method for determining the position of person 130 based on the strength of the wireless signal between some or all of the smart electrical accessories in a building 110 shall now be described.

A background signal strength is recorded for the building 110 without occupants when the system is installed, or when changes are made to the arrangement of wireless accessories or significant changes are made to the layout of the building 110. The signal strength between each wireless transmitter 149 and wireless receiver 148 is recorded for a wireless transmission of known power in the absence of person 130. The wireless signal transmitted from each wireless transmitter 149 includes an identifier which allows a wireless receiver 148 in another smart electrical accessory to identify which wireless transmitter 149 and wireless receiver 148 pair the signal strength relates to. This signal strength information is transmitted to server 135 which stores it as the background signal strength.

To determine whether person 130 might be present in the building 110, each electrical accessory transmits wireless signals at a known power from the wireless transmitter 149 and records the signal strength received by its wireless receiver 148 from wireless transmitters 149 in some or all of the other electrical accessories. The wireless signal strengths recorded between each pair of wireless transmitters 149 and wireless receivers 148 are transmitted to the server 135. The server 135 calculates the difference between the average signal strength between some or all of the electrical accessories and the average signal strength between the same electrical accessories recorded for the background signal strength. If the difference is above a threshold, this indicates that there has been a change in signal strength that might be indicative of the person 130 being present in the building 110. The server 135 monitors for changes in the difference over time which may indicate that the person 130 is moving around the building 110. The threshold is selected to avoid false readings caused by normal fluctuations in signal strength. If the transmitted power differs from the transmitted power used for the background signal strength measurements, appropriate adjustments are made before calculating the difference.

Whenever the server 135 notes a difference, or a change in the difference, above the threshold, the server 135 may proceed to calculate the actual location of the person 130.

To help pinpoint the location of the person 130, the server 135 may store signal strength "fingerprints". Each fingerprint contains the signal strength between each of the electrical accessories when the person 130 is standing in a particular location in the building 110. The fingerprints are generated when the system is installed, or when changes are made to the arrangement of wireless accessories or significant changes are made to the layout of the building 110. To generate the fingerprints, the person 130 is directed to stand in multiple positions around the building 110, for example, by instructions received on a portable electronic device. For each position, the signal strength between each wireless transmitter 149 and wireless receiver 148 pair is measured and recorded as a fingerprint on the server 135, along with the known position the person 130 was standing in at the time the fingerprint was recorded.

To determine the location of the person 130 in an unknown position, the measured signal strength between some or all wireless transmitter 149 and wireless receiver 148 pairs is compared against the fingerprints to find the closest match, or to interpolate between individual fingerprints in the case that the position of the person 130 is between fingerprints.

The server 135 can use the location of the person 130 to control other electrical devices or electrical accessories. For example, the server 135 can send a control signal to light switches 150a close to the person's location to turn the light switch 150a on, while sending a control signal to light switches 150b away from the person's location to turn the light switch 150b off to save power.

Although the invention has been described in terms of certain examples, the skilled person will appreciate that modifications can be made, various features combined with other features, or certain features omitted, without departing from the scope of the appended claims.

Although the system has been described as determining the position of the person 130 in a building 110, the system may determine the position of the person 130 in only a part of the building 110, such as an individual room, by using only the electrical accessories in and/or around that room.

The invention has been described in terms of determining the presence and/or location of a person in a building. Examples of buildings include dwellings, industrial, commercial, healthcare, government and similar premises. However, the invention is equally applicable to determining the presence and/or location of a person in other areas, such as an outdoor arena, sports pitch and garden.

Claims

1. A system for indicating presence of a person in a region, the system comprising :

a plurality of electrical accessories arranged around the region, wherein each electrical accessory comprises:

a wireless transmitter configured to transmit a wireless signal; and a wireless receiver configured to receive a wireless signal transmitted by another electrical accessory of the plurality of electrical accessories; and

a processor configured to indicate presence of the person based on the wireless signals transmitted and received between at least some of the plurality of electrical accessories.

2. The system of claim 1, wherein each electrical accessory is capable of reporting received signal strength.

3. The system of either of claims 1 or 2, wherein one or more of the electrical accessories is one of: an electrical socket, an electrical switch, a light switch, a heating control, a control panel, a touch screen, a wireless access point, a device gateway, and a smoke, heat or fire detector.

4. The system of any preceding claim, wherein each electrical accessory is arranged in association with : a wall, floor or ceiling of a building.

5. The system of any preceding claim, wherein presence is indicated based on change in signal strength between the transmitted and received wireless signals over time.

6. The system of any preceding claim, further comprising a memory storing a background signal strength corresponding to the signal strength between each wireless transmitter and wireless receiver for the region without occupants.

7. The system of claim 6, wherein presence is indicated by comparing the signal strength between each wireless transmitter and wireless receiver with the background signal strength.

8. The system of any preceding claim, wherein the processor sends a control signal to control an electrical device or an electrical accessory when presence is indicated.

9. The system of any preceding claim, wherein the processor is further configured to determine a location of the person in the region by comparing the signal strength between each wireless transmitter and wireless receiver with fingerprints.

10. The system of claim 9, wherein each of the fingerprints comprise signal strengths between each wireless transmitter and wireless receiver for the person standing in a particular position around the region.

11. The system of either of claims 9 or 10, wherein the processor sends a control signal to control an electrical device or an electrical accessory based on the location of the person.

12. The system of any preceding claim, wherein processing takes place at a server in communication with each of the electrical accessories or in a microcontroller located in one or more of the electrical accessories.

13. The system of any preceding claim, wherein the electrical accessories are arranged in multiple rooms around a building.