SE2250669A1

SE2250669A1 - HVAC control using mobile devices

Info

Publication number: SE2250669A1
Application number: SE2250669A
Authority: SE
Inventors: Björn Nord
Original assignee: Ecoclime Group AB
Priority date: 2022-06-02
Filing date: 2022-06-02
Publication date: 2023-05-12

Abstract

There is provided a method for controlling a HVAC device in a building, the method involving at least three registration devices configured to receive an electromagnetic signal from a mobile device, said electromagnetic signal providing an identity, where the position of each the registration devices in the building is known, the method comprising the steps of, a) the at least three the registration devices determining the signal strength for at least a first signal providing a first identity and second signal providing a second identity, where the determination is carried out within a time frame, b) using the signal strength to determine, by multilateration, the positions in the building from which each of the first and the second identities was provided, c) determining, if the positions from which the first and the second identity differs with a distance less than a threshold distance, that the first identity and the second identity has been provided from the same mobile device, d) using the information from step c) to control a HVAC system.

Description

HVAC control using mobile devices Field of the invention This invention relates to control of HVAC (Heat Ventilation and Air Conditioning) systems by tallying the number of persons by detecting their mobile devices.

Background Because of raising energy prices and carbon footprints, there is a need to make the use of HVAC systems more efficient. lt would for example be very useful if HVAC system can be controlled based on the number of persons in a building or in a room. Many different strat- egies for this have been proposed, such as using IR detectors to detect individuals.

Mobile phones repeatedly broadcast their identity and one person typically carries one mo- bile phone. The use of tallying persons by detecting their mobile phones, and using the in- formation to control HVAC systems, has been suggested for example by EP 3 237 811.

However, detecting mobile phones has become more complex since mobile phone produc- ers such as Apple and Samsung began configuring their phones such that the MAC addresses of the phones are dynamic and therefore changes frequently. The MAC addresses pre- sented by mobile phones are random and very difficult to track. MAC address dynamics is used both on the software level and the hardware level. This makes determining the num- ber of persons using MAC addresses very difficult as the number of persons may be grossly overestimated, sometimes with a factor of up to twenty.

Summary of the invention ln a first aspect of the invention there is provided a method for controlling a HVAC device in a building, the method involving at least three registration devices configured to receive an electromagnetic signal from a mobile device, said electromagnetic signal providing an identity, where the position of each the registration devices in the building is known, the method comprising the steps of, a) the at least three the registration devices determining the signal strength for at least a first signal providing a first identity and second signal providing a second identity, where the determination is carried out within a time frame, b) using the signal strength to determine, by multilateration, the positions in the building from which each of the first and the second identities was provided, c) determining, if the positions from which the first and the second identity dif- fers with a distance less than a threshold distance, that the first identity and the second identity has been provided from the same mobile device, d) using the information from step c) to control a HVAC system.

The method makes it possible to tally persons in a building even if the mobile devices use dynamic identities.

The method may comprise the step of before determining the signal strength in step a), carrying out the initial step of the plurality of registration devices detecting a plurality of identities during a predetermined time. The predetermined time may be at least 10 sec- onds. The initial step may comprise determining the signal the signal strength for each iden- tity.

The identity may be provided from the mobile device in response to an interrogation sig- nal from one registration device. The registration device which sends the interrogation sig- nal may be selected based on the signal strength determined in the initial step. ln a preferred embodiment the identities are MAC addresses, and the signal strength in step a) is determined by a registration device sending a Request to Send signal and receiv- ing a Clear to Send signal, where the signal strength ofthe Clear to Send signal is deter- mined and used in step b).

The signal strength information may be associated with a timestamp. The time frame in step a) may be at most 0.1 seconds. ln one embodiment at least four different identities are detected and clustering their posi- tions is used to group the identities in at least two groups in step c). ln a second aspect of the invention there is provided a system for controlling a HVAC de- vice the system comprising a plurality of registration devices configured to receive an elec- tromagnetic signal providing an identity of a mobile device, where the position of each the registration devices in a building is known, the system further comprising a control device where the registration devices are configured to: determining the signal strength for at least a first and a second identity, where the determination is carried out within a time frame, and configured to provide the signal strengths associated with the identities to the control device, the control device being configured to use the signal strength to deter- mine, by multilateration, the position in the building for each of the first and the second identities and being configured to determining, if the position for the first and the second identity differs with a distance less than a threshold distance, that the first identity and the second identity has been provided from the same mobile device, and configured to use the information to control the HVAC system. ln a third aspect ofthe invention there is provided a ceiling element comprising a surface configured to be arranged as a horizontal part of a ceiling, a HVAC device configured to be controlled by a control device, a registration device configured to periodically detect MAC addresses during a predetermined time and to provide the MAC addresses to the control device, and configured to, in response to a control signal from the control device, said control signal comprising a MAC address, send a Request to Transmit signal to a MAC ad- dress, and in response thereto, receive a Clear to Send signal, and further configured to determine the strength ofthe Clear to Send signal, and to provide the signal strength in- formation for the MAC address to the control device, the registration device further con- figured to receive a control signal for the HVAC device from the control device and provide the control signal to the HVAC device.

The ceiling element provides a convenient manner to provide a HVAC device and a registra- tion device for a drop ceiling.

Drawings The accompanying drawings form a part of the specification and schematically illustrate preferred embodiments of the invention, and serve to illustrate the principles of the inven- tion.

Fig. 1 is a schematic drawing of a system.

Fig. 2 is a schematic drawing of a system in a space in a building.

Fig. 3 shows various communication steps in a method.

Fig. 4 is a flowchart that shows a method.

Fig. 5 is a schematic drawing of a space in a building seen from above.

Fig. 6 is a schematic drawing of a ceiling element as seen from below.

Fig. 7 is a schematic drawing of a ceiling element as seen from the side.

Fig. 8 is a schematic drawing of software modules of a control device.

Detailed description With reference to Figs 1 2, system 20 comprises at least one HVAC device 1 such as a venti- lation device, a heating device, a room controller, a Variable Air Volume (VAV) controller, or an air conditioning (A/C) device. The HVAC device 1 provides heating, ventilation or A/C to the space 4. The HVAC device 1 is controlled by a control device 2. The control device 2 is in communication with a plurality, preferably at least three, registration devices 3abc. The registration devices 3abc are arranged in a building, more preferably in a space 4, such as a room. For example, the registration devices 3abc may be attached to the ceiling 5 or inte- grated into a drop ceiling. The registration devices 3abc may be arranged in the space be- tween a ceiling and a drop ceiling. The registration devices 3abc are preferably arranged in the space 4 where the HVAC device 1 is arra nged to provide for example heating, ventilation or A/C. The HVAC device 1 being controlled may be located in the space 4 or outside the space 4.

System 20 is able to detect the number of persons in the space 4 by detecting mobile de- vices carried by persons 6 in the room and to control the HVAC device 1 in response to the number of persons detected in the room.

The control device 2 is able to control the HVAC device 1 as is known in the art. The control device 2 is able to determine the number of persons in the space 4 as detected herein and use that information to provide a control signal to the HVAC device 1. For example, if the control device 2 detects that the number of persons in space 4 increases, the control device 2 may provide a signal to HVAC device 1 that is a ventilation device to increase ventilation. Hence the control device 2 is able to provide a control signal to HVAC device 1. The control device 2 may for example increase or decrease flow in a heating device or may change a set point in a heating or cooling device, in order to provide more or less heating or cooling to space 4. The HVAC device 1 may be located in the space 4, adjacent to space 4 or at a dis- tance from space 4. The control signal may be provided to the HVAC device 1 in any suitable manner, for example wireless or by wire. ln some embodiments the control signal from the communication device 2 to the HVAC device 1 is provided via a registration device 3. For example, a control device 2 may provide a signal to registration device 3 using a Wi-Fi net- work. The registration device 3 may the provide the control signal to the HVAC device 1. ln some embodiments the registration device 3 provides the control signal to the HVAC device 1 in a wire bound manner.

Registration devices 3abc are arranged in the space 4 at known locations in the space 4. Registration devices 3abc may be able to mimic the behavior of a wireless access points for a mobile device 11 (such as a Wi-Fi access point) to a certain extent but do typically not provide a wide area network connections such as internet access for a mobile device 11. The control device 2 is able to communicate with the registration devices 3 or the HVAC device 1 using any suitable wireless or wired network technology, of which a wireless tech- nology, in particular Wi-Fi is preferred. The network for communication in system 20 is pref- erably the same which is used by registration devices 3abc to receive and track identities of mobile devices 11, as described below, which preferably is Wi-Fi. Wi-Fi is a wireless network standard as defined by for example IEEE 802.11.

Figs. 2 shows examples of a space 4 which is a room with registration devices 3abc, and a person 6 carrying a mobile device 11. Registration devices 3abc are arranged in known lo- cations with respect to the horizontal plane. The vertical location of registration devices 3 in respect of space 4 may also be known. However, typically registration devices 3 will be located at approximately the same height in relation to the ceiling 5. ln some embodiments a registration device 3 may be comprised in a control device 2.

Registration devices 3abc primary serve to detect mobile devices 11 in order to tally them. Registration devices may be able to participate in some aspects of wireless networking with mobile devices 11 using suitable protocols, such as for example Wi-fi. Hence, registration devices may be able to mimic the actions of wireless access points in some aspects. Regis- tration devices 3abc may also be able to participate in a wireless network, such as a Wi-Fi network, in particular for communication with control device 2 and HVAC device 1.

I\/|obile device 11 is able to participate in a wireless network, such as a Wi-Fi network by using an identity, which in the case of a Wi-Fi network is a MAC address. The identity may be a unique identity. The identity may for example be any suitable combination of letters and numbers. The identity may be stored in the mobile device 11 in a digital format and may be provided in a digital format. The identity is typically dynamic so that it changes in a manner configured in the mobile device 11, typically in the operating system ofthe mobile device 11. The mobile device 11 may use more than one identity. The way the identity changes is configured in the mobile device 11 and differs between manufacturers of mobile devices such as Apple and Samsung.

I\/|obile device 11 typically provide its network identities by transmitting them using an elec- tromagnetic signal. This may be done using a so-called probe request. This may occur at different intervals, depending on the use or configuration of the mobile device 11. For ex- ample, some mobile devices 11 are configured to provide their identities with a lower fre- quency when the mobile device is not moving. ln that case, minutes may elapse between probe requests.

Registration devices 3abc are able to determine the signal strength of the electromagnetic signal that provides the identity which is received from a mobile device 11. This information may for example be determined as Received Signal Strength lndicator (RSSI).

A method will now be described with reference to Figs. 2-5.

A number of mobile devices 11 may be present and may come and leave space 4, as they are carried by persons 6 visiting the space 4. These mobile devices 11 transmit their identi- ties, for example MAC addresses, for example as so-called probe requests. ln step 100 a plurality of registration devices 3abc detects identities of mobile devices 11, such as for example MAC addresses (signal 200). This is preferably carried out for a predetermined time which may be from 10 seconds to 10 minutes, more preferably for from 30 seconds to 5 minutes. The predetermined time may be at least 10 seconds or more preferably at least 60 seconds. Optionally, the signal strength of the signal 200 that provides the identity is also detected by the registration device 3abc at this step. Hence, during step 100 the system 20 collects identities of mobile devices 11 that are present in space 4. ln step 101, the identities and the signal strength information are provided to the control device 2 (signal 201). This may be done continuously during step 100 or in a batch after step 100 has been concluded. The control device 2 stores the identities and the signal strength information, for example in a list. Control device 2 may comprise a registration device con- trol module 30 for timing and communication with registration devices 3 and storing of identities. Step 101 and the following steps are prefera bly carried out immediately after the end ofthe predetermined time in step 100.

The list of identities may be managed in any suitable manner. ln one embodiment, a identity may be deleted from the list unless it has been provided from a registration device within a predetermined time. The predetermined time may be for example from 1 minute to 10 minutes.

The control device 2 in step 102 may provide a control signal 202 to the registration devices 3abc which causes the registration device 3a which receives control signal 202 to provide an interrogation signal 203, such as a RTS (Request to Transmit) signal. Control signal 202 may comprise the identities to which the selected registration device 3a should provide the interrogation signal 203. Control signal 202 may typically comprise a plurality of identities which should be interrogated. The control signal 202 for a certain identity is preferably pro- vided to a subset ofthe registration devices 3abc, preferably one ofthe registration devices 3a, which may be the registration device 3a with the recorded the strongest signal strength from the identity in step 100. Hence interrogation signal 203 will be sent from one registra- tion device 3a which may be the registration device 3a which is likely to be closest to the mobile device 11. Control signal 202 may also be provided to a plurality of registration de- vices 3abc, for example all registration devices 3abc which has detected the identity in step 100. Preferably all control signals 202 at this step are provided within a short time window, which may be from 1 ms to 50 ms. This provides synchronization of the replies from the mobile devices 11 (step 204). ln step 103 the registration devices 3a provides an interrogation signal 203 (for example a RTS signal) to the mobile devices 11 with the identities provided from control device 2. ln- terrogation signals 203 may be provided to more than one mobile device 11. The interroga- tion signal 203 makes the device 11 with the corresponding identity provide a reply signal 204 which comprise the identity ofthe mobile device 11. The reply signal may be a Clear to Send (CTS) signal. This is preferably carried out in a synchronized manner or almost synchro- nized manner so that the reply signal 204 is provided simultaneously or almost simultane- ously from the various mobile devices 11. Wi-Fi systems and many other systems for wire- less network communication including mobile devices 11 are configured with very short response times. When one mobile device 11 provides a first and a second reply signal 204 the signals are preferably provided within at most 500 ms, more preferably at most 300 ms more preferably at most 100 ms and most preferably within 20 ms. ln step 104 reply signal 204 (which may be a CTS signal) is detected by a plurality of regis- tration devices 3abc, preferably at least three registration devices 3abc. The signal strength of reply signal 204 is determined by each of the registration devices 3abc. This provides signal strength information. This signal strength information is stored together with a time point, such as a time stamp.

Steps 102-104 is carried out for at least a first identity and a second identity. Hence each of registration devices 3abc will receive signal strength information for at least two different identities. The signal strength information is provided from registration devices 3abc to the control device 2 in signals 205abc in step 105. The signal strength information is provided together with the identities of the mobile device 11, as determined in step 104. ln step 106 the control device 2 uses multilateration (for example trilateration) to determine the position of the mobile device 11 that has sent the first identity in step 204 and the mo- bile device 11 which has sent the second identity in step 204, using the signal strength in- formation. Control device 2 may comprise multilateration software 32 for carrying out this step. Because the relative position of each ofthe registration devices in the space 4 is known (Fig. 5) the position from which the first identity is sent and the position from which the second identity is sent can be determined. Hence signal strength values 3aA, 3bA and 3cA is used to determine the position from which a first identity A is sent and signal strength values 3aB, 3bB and 3cB are used to determine the position from which second identity B is sent. The distance 13 between the positions A and B is then determined. ln some embodiments, the space 4 is considered as a horizontal plane, hence the vertical position ofthe mobile device 11 may be disregarded in some embodiments.

Preferably each of the registration devices 3a, 3b, 3b stores a time point for receiving the reply signal 204. For example, a time stamp can be used. The time stamp may be used to make sure that signal strength data that is collected within the predetermined time frame. The registration devices 3a, 3b and 3c each provide the identities, the signal strength and the time points to the control device 2 in step 105. lt is preferably determined by control device 2 in step 107 that the signals 204 from the first identity and the second identity have been received by each of the three registration de- vices 3a, 3b and 3c within a predetermined time frame. This step may be carried out by device tracking software 33 of control device 2. The time frame is selected such that a per- son should not be able to move more than the threshold distance during the time frame. The time frame may for example be less than 500 ms, more preferably less than 300 ms and more preferably less than 100 ms and most preferably less than 20 ms. ln some embodi- ments it is assumed that the used network protocol and the hardware used carries out the steps within this time frame. Hence the mobile device 11 is preferably carried by a person 6 who is a pedestrian (and not for example in a car). The threshold distance 13 may be for example 30 cm or less, more preferably 20 cm or less, more preferably 10 cm or less and most preferably 1 cm or less. lf the distance between positions for the mobile phone 11 from which the first and second identities have been provided in step 204 differ from each other by less than the threshold distance and received within a predetermined time frame, the two identities are deemed to emanate from the same mobile device 11. lf the distance is more than the threshold distance, it is deemed that there are two different mobile devices 11.

After the registration devices 3abc have provided the identities to the control device 2, sys- tem 20 may again begin carrying out step 100. Preferably the method of Figs. 3 and 4 is carried out repeatedly. Preferably the identity collection step 100 is carried out for a 11 comparatively long time compared to the other steps. Whereas step 100 preferably is car- ried out for a predetermined time which may be from 10 seconds to 10 minutes, the other steps preferably take less than 1 second to complete.

The information from step 107 may be used by the control device 2 to tally the number of persons in the space 4 and to control the HVAC device 1.

When at least four identities have been positioned in step 106, clustering of the position may be used to assign the identity to groups. For example, k-means clustering may be used.

Figs. 6 and 7 shows a ceiling element 50. The ceiling element 50 may comprise an essentially flat surface 51 arranged to form a part of a ceiling such as a drop ceiling. Neighboring stand- ard drop ceiling tiles are indicated with 53a and 53b. The surface 51 is intended to form horizontal part of a ceiling. Surface 51 is arranged to be facing downwards. Ceiling element 50 may be arranged to be received by a drop ceiling holder such as drop ceiling grid. The ceiling element 50 may be dimensioned to fit in a standard drop ceiling. For example, the surface 51 may be square and have dimensions of for example 600 mm x 600 mm or 1200 mm x 600 mm, although any suitable dimensions may be used. For example, in the US, standard drop ceiling sizes are 2'x 2' and 2'x 4'. Hence the ceiling element 50 is arranged to be used as a drop ceiling tile.

The ceiling element 50 also comprises a HVAC device 1 arranged to be controlled by a HVAC control signal. The control signal may for example control a valve of HVAC device 1, in order to open or close the valve. The HVAC device 1 may for example be a VAV-controller. Surface 51 may have openings 52 for letting in our out air, such as ventilation air, cooled air or heated air from the HVAC device 1 of the ceiling element 50, which openings 52 may be distributed across a part or whole of the flat surface 51. The HVAC device 1 may comprise an air duct, which may be in fluid connection with the openings 52.

The ceiling element 50 further comprises a registration device 3 arranged to receive a wire- less HVAC control signal, preferably using Wi-Fi, for the HVAC device 1 from a control device 12 2 and provide the HVAC control signal in a wire bound manner or wireless manner to the HVAC device 1. ln a preferred embodiment the control signal is provided from registration device 3 to HVAC device 1 via wire element 54.

The registration device 3 is further configured to periodically detect identities of mobile devices 11 during a predetermined time and to provide the identities to the control device 2 as described herein with reference to Fig. 3 and 4. Hence, the registration device 3 may be configured to, in response to a control signal 202 from the control device 2, send a inter- rogation signal 203, and in response thereto receive a reply signal 204 from a mobile device, to determine the signal strength of the reply signal 204 and to provide the signal strength information for the identity to the control device 2. The registration device 3 prefera bly uses a Wi-Fi protocol to carry out the method as described above with reference to Figs. 3-4. Hence, the identity is preferably a MAC address, the interrogation signal is preferably a RTS signal and the reply signal is preferably a CTS signal.

Hence ceiling element 50 may form part of system 20 together with at least two other reg- istration devices 3 and a control device 2. By using ceiling element 50 a HVAC device 1, and a registration device 3 may installed in a space 4 in a convenient manner. I\/|oreover, in some embodiments, ceiling element 50 may be provided with a control device 2. lt is understood that the present methods and system is computer-implemented, using dig- ital computer equipment. The various embodiments and components described herein such as HVAC device 1, control device 2 and registration devices 3abc and communication be- tween these components uses digital computer technology for storing and handling digital information and signals as well as suitable hardware and software, including for example suitable digital processors, digital memories, input means, output means, buses and com- munications interfaces. A user may be able to make input using for example a keyboard, a mouse or a touch screen. Output may be provided on for example a display. ln general, each of registration device 3abc, control device 2 and HVAC device 1 may com- prise a memory, a processor and a bus, and a communication interface. The memory of 13 registration device 3abc comprises software for participating in a wireless network, such as Wi-Fi and for commutation with control device 2. The memory of control device 2 may comprise network software 30, registration device control module 31, multilateration soft- ware 32 and tracking software 33. The tracking software 33 may be able to provide infor- mation about the number of persons to a HVAC control module 34, which may be able to provide a control signal to HVAC device 1 (Fig 8).

The methods herein may be implemented with any suitable combination of software and hardware. Any suitable programming language may be used for the software units and methods described.

The system and methods have been primarily described using embodiments using Wi-Fi technology. However, any other useful wireless technology may be used such as Bluetooth or 5G, CDMA or similar network. Various communication steps between the components, except where a mobile device 11 is involved, may comprise wired communication such as Ethernet. Data communication in system 20 may be encrypted. Information may be ex- changed over a wide area net such as internet.

While the invention has been described with reference to specific exemplary embodiments, the description is in general only intended to illustrate the inventive concept and should not be taken as limiting the scope of the invention. The invention is generally defined by the claims.

Claims

1. A method for controlling a HVAC device in a building, the method involving at least three registration devices configured to receive an electromagnetic signal from a mobile device, said electromagnetic signal providing an identity, where the posi- tion of each the registration devices in the building is known, the method compris- ing the steps of, a) the at least three the registration devices determining the signal strength for at least a first signal providing a first identity and second signal providing a second identity, where the determination is carried out within a time frame, b) using the signal strength to determine, by multilateration, the positions in the building from which each of the first and the second identities was provided, c) determining, if the positions from which the first and the second identity dif- fers with a distance less than a threshold distance, that the first identity and the second identity has been provided from the same mobile device, d) using the information from step c) to control a HVAC system.

2. The method of claim 1 comprising, before determining the signal strength in step a), carrying out the initial step of the plurality of registration devices detecting a plurality of identities during a predetermined time.

3. The method of claim 2 where the predetermined time is at least 10 seconds.

4. The method of claim 2 or 3 where the signal strength for each identity is detected during the initial step.

5. The method of any one of claims 1 to 4 where the identity is provided from the mobile device in response to an interrogation signal from one registration device. The method of claim 4 and 5 where the registration device which sends the inter- rogation signal is selected based on the signal strength determined in the initial step. The method of any one of claims 1 to 6, where the identities are MAC addresses, and the signal strength in step a) is determined by a registration device sending a Request to Send signal and receiving a Clear to Send signal, where the signal strength ofthe Clear to Send signal is determined and used in step b). The method of any one of claims 1 to 7 where the signal strength information is as- sociated with a timestamp. The method of any one of claims 1 to 8 where the time frame in step a) is at most 0.1 seconds. The method of claims 1 to 9 where at least four different identities are detected and clustering their positions is used to group the identities in at least two groups in step c). A system for controlling a HVAC device the system comprising a plurality of regis- tration devices configured to receive an electromagnetic signal providing an iden- tity of a mobile device, where the position of each the registration devices in a building is known, the system further comprising a control device where the regis- tration devices are configured to: determining the signal strength for at least a first and a second identity, where the determination is carried out within a time frame, and configured to provide the signal strengths associated with the identities to the control device, the control device being configured to use the signal strength to de- termine, by multilateration, the position in the building for each ofthe first and the second identities and being configured to determining, if the position for the first and the second identity differs with a distance less than a threshold distance, thatthe first identity and the second identity has been provided from the same mobile device, and configured to use the information to control the HVAC system. A ceiling element comprising a surface configured to be arranged as a horizontal part of a ceiling, a HVAC device configured to be controlled by a control device, a registration device configured to periodically detect MAC addresses during a pre- determined time and to provide the MAC addresses to the control device, and con- figured to, in response to a control signal from the control device, said control sig- nal comprising a MAC address, send a Request to Transmit signal to a MAC ad- dress, and in response thereto, receive a Clear to Send signal, and further config- ured to determine the strength of the Clear to Send signal, and to provide the sig- nal strength information for the MAC address to the control device, the registra- tion device further configured to receive a control signal for the HVAC device from the control device and provide the control signal to the HVAC device.