FR3090164A1 - Method for locating a device capable of transmitting Bluetooth signals and associated system - Google Patents

Abstract

The subject of the present invention is a method for locating a device, by a system comprising at least one antenna and a computer, the method comprising the implementation by the system of the steps of: continuous measurement, of the power received, by each antenna, of a Bluetooth signal emitted by a device, constitution of a history comprising a plurality of powers received measured by each antenna at different times, including at least the last power measured by one of the antennas, the history making it possible to obtain information concerning the trajectory of the device, and determination, by the computer, from the history, of a location of the device at the time when the last power is measured. Figure 1

Description

Description

Title of the invention: Method for locating a device capable of transmitting Bluetooth signals and associated system

Technical area

The present invention relates to a method of locating a device capable of transmitting Bluetooth signals and a system capable of implementing said method. State of the art

There are systems for locating devices based on the reception by one or more antennas of Bluetooth signals emitted by the device.

There are different types of systems for locating a device capable of transmitting a Bluetooth signal such as a smart phone, for example. Some devices detect the presence of the device in an area close to the transmitter when the power received by the antenna is above a predetermined power threshold. Other systems comprising several antennas oriented towards the area considered are capable of locating the device within the area covered by the antennas by triangulation for example. The distance between a receiving antenna and the transmitting device is then evaluated as a function of the attenuation calculated as a function of the power received by the antenna and the power of the signal transmitted by the device.

The localization of devices using Bluetooth signals has drawbacks. On the one hand, the attenuation of the Bluetooth signals varies according to the conditions of use or wearing of the device so that it is difficult to locate a device with precision or reliability. Indeed, the real power emitted by the device is attenuated depending on whether the wearer has the device in his hand, in one or the other pocket. In addition, the signal strength received by the antenna may vary depending on radio interference.

Statement of the invention

The invention aims in particular to overcome the drawbacks of the prior art described above.

In particular, an object of the invention is to provide a method and a system for locating a device capable of transmitting more reliable and more precise Bluetooth signals.

Another object of the invention is to provide a method and a system for locating a device capable of transmitting Bluetooth signals, the method and the system being less sensitive to radio interference and to variations in power actually emitted by the device.

In this regard, the invention relates, according to a first aspect, to a method of locating a device, by a system comprising at least one antenna and a computer, the method comprising the implementation by the system of stages of: - continuous measurement, of the power received, by each antenna, of a Bluetooth signal emitted by a device,

- constitution of a history comprising a plurality of received powers measured by each antenna at different times, including at least the last power measured by one of the antennas, the history making it possible to obtain information concerning the trajectory of the device, and

- the determination, by the computer, from the history, of a location of the device at the time when the last power is measured.

According to one embodiment, the method further comprises:

- the determination, for each of the powers in the history, of the time interval between the measurement of the power considered and the measurement of the last power measured, and

- in which the location of the device is obtained from the history of the measured powers and the associated time intervals.

According to one embodiment, the determination of the location of the device comprises the use of a model obtained by learning from a data set comprising at least a plurality of histories of measured powers, and for each history, at least one piece of information on the location of the device in connection with the moment of acquisition of one of the measured powers of the history, preferably the last.

According to one embodiment, the determination of the location of the device comprises the use of a model obtained by learning from a data set comprising a plurality of histories of measured powers, and for each history, associated time intervals and at least one location information of the device in connection with the moment of acquisition of one of the measured powers of the history.

According to one embodiment, the determination of the location of the device is a determination of an area in which the device is located among a plurality of predetermined areas, and the model used is a classification model obtained by learning from a data set comprising a plurality of histories of measured powers, and for each history, the associated time intervals and the zone in which the device is located at the time when the last power is measured.

According to one embodiment, the determination of the location of the device comprises the use of a predictive model of the position of the device at the time when the last power is measured, the predictive model being obtained by learning from a data set comprising a plurality of histories of the measured powers, and for each history, the associated time intervals and a position of the device at the time when the last power is measured.

According to one embodiment, the position of the device comprises a distance from a reference point.

According to one embodiment, the position of the device further comprises an angle relative to a reference direction.

According to one embodiment, each antenna comprises several reception channels, the reception channels corresponding to a different frequency and polarization, and:

- for an antenna, the continuous measurement of the power received from a Bluetooth signal emitted by the device comprises a power measurement on a plurality of channels, and

- the constitution of the history includes, for each antenna, the selection of the last power measured by the antenna among the powers measured on each channel of the antenna.

According to one embodiment, the system is integrated into a vehicle comprising at least one door and the system is further configured to control the locking and unlocking of each door according to the location information of the device.

In addition, the invention relates, according to a second aspect, to a computer program product comprising code instructions for implementing a method comprising the following steps:

- reception of data from at least one antenna measuring powers received by each antenna of a Bluetooth signal emitted by a device,

- constitution of a history comprising a plurality of received power measured by each antenna at different times including at least the last received power measured by one of the antennas, the history making it possible to obtain information concerning the trajectory of the device, and

- determination, from the history, of a location of the device when the last power received is measured, when it is implemented by a computer.

In addition, the invention relates, according to a third aspect, to a system suitable for implementing a method for locating a device as described above, comprising:

- at least one antenna configured to measure the power received from a signal

Bluetooth emitted by a device,

- a computer configured for:

• constitute a history comprising a plurality of received powers measured by each antenna at different times including at least the last power measured by one of the antennas, the history making it possible to obtain information concerning the trajectory of the device, • to determine, at from the history, a location of the device at the time when the last power is measured.

The present invention also relates, according to a fourth aspect, a motor vehicle comprising a system adapted for the implementation of a method of locating a device as described above.

The present invention makes it possible to make reliable and more precisely determine the location of a device capable of transmitting Bluetooth signals, in particular through the use of the history of the received powers measured by each antenna at different times. For example, the history of the received powers makes it possible to take into account an increase or a decrease in the signal detected by each antenna and thus to take into account the trajectory of the device. The location of the device is thus less sensitive to radio interference and to the wearing conditions of the device. In addition, taking into account the time interval between each power in the history and the last power measured makes it possible to know whether the powers received have been measured or not for one or more antennas for a determined period. This information refines the determination of the location of the device. In addition, the use of models obtained by learning makes it possible to take into account a larger amount of data and to further improve the reliability and accuracy of localization.

Description of the drawings

The drawings and the description below essentially contain elements of a certain nature. They can therefore not only serve to better understand the present invention, but also contribute to its definition, if necessary.

[Fig.l]

FIG. 1 represents a method of locating a device by a system comprising at least two antennas and a computer, according to one embodiment.

[Fig.2]

FIG. 2 schematically represents a vehicle equipped with a system according to the invention, according to one embodiment.

Description of the embodiments

Figure 1 shows a method of locating a device capable of transmitting Bluetooth signals by a system comprising at least one antenna 31, 32, 33, 34 capable of receiving Bluetooth signals, a computer and a memory, according an embodiment.

The location method comprises a step S100 of continuous measurement of the power received by each antenna of a Bluetooth signal emitted by the device, a step S200 of constitution of a history comprising a plurality of measured received powers by each antenna at different times, an optional step S300 of determining, for each of the powers of the history, the time interval between the measurement of the power considered and the last power of the history, and a step S400 of determination, by the computer, from at least the history of the measured powers, of a location of the device at the time when the last power is measured.

The history of the received powers makes it possible to take into account the trajectory of the device and to determine the location of the device with more reliability. For example, the history of the powers received makes it possible to take into account an increase or a decrease in the signal detected by one or more antennas. Depending on the evolution of the power of the received signals, it is possible to assess whether the device is approaching or moving away from one or more antennas and thus to take into account the trajectory of the device. The location is therefore more precise and less sensitive to the variations in power actually emitted by the device, the power actually emitted can vary depending on the position of the device on the carrier and reflections of the Bluetooth signal on elements of the environment.

The determination of the location can also take into account, when step S300 is implemented, the time interval between each power of the history and the last power measured. Thus, the determination of the location also takes into account information according to which the powers received have been measured or not for one or more antennas for a determined period.

In one embodiment, each antenna comprises several reception channels, each of the reception channels corresponding to a different frequency and polarization. The polarization corresponds to the spatial directivity of the antenna for the reception of Bluetooth signals on the associated channel. Step S100 therefore comprises here the continuous measurement of the power received on a plurality of channels, each measurement of the received power being time-stamped using a clock signal common to all the antennas of the system.

The step S200 of constitution of the history comprising a plurality of powers received measured by each antenna at different times then comprises, a sub-step S210 for selecting, for each antenna, the last power measured from the powers measured on each antenna channel. Step S200 also includes a sub-step S220 for storing the value of the last received power measured for each antenna. Optionally, the sub-step S220 can include the storage of Γ time stamp corresponding to the received power stored.

When the received power measured by the antennas is a RSSI power ("Received Signal Strength Indication" in English) expressed in dB, the method can include a step of converting the value of the received RSSI power into a power of value linear in mW. This conversion makes it possible to gain precision when determining the location of the device during the implementation of step S400. This step can be carried out at different times before the implementation of step S400.

The sub-steps S210 and S220 are repeated periodically in order to constitute a history of the powers received measured by each antenna and of the corresponding time stamps. The history is preferably of predetermined length. The history preferably includes at least the last ten values of the received powers measured by each antenna.

In another embodiment, step S100 comprises the continuous measurement, for each antenna, of the power received on a single channel. In this case, step S200 does not include the sub-step S210 and only step S220 is repeated periodically in order to constitute the history.

In the embodiment described here, the method comprises step S300 of determining, for each of the powers of the history, the time interval between the measurement of the power considered and the measurement of the last power considered and step S400 is a step of determining, by the computer, from the history of the powers measured and the associated time intervals, of a location of the device at the time when the last power is measured. The location of the device can be a position of the device in a reference point or relative to a determined point or an area in which the device is located.

In one embodiment, step S400 comprises a step S410 of using a model obtained by learning from a data set comprising a plurality of histories of measured powers, and for each history, associated time intervals and at least one location information of the device in connection with the moment of acquisition of one of the measured powers of the history. In one embodiment, the location information of the device is linked to the last measured power in the history.

In one embodiment, the model of step S410 is a classification model obtained by learning from a data set comprising a plurality of histories of measured powers, and for each history, the intervals of associated times and the zone in which the device is located at the time when the last power is measured. The learning classification model can be a neural network, or a forest of decision trees for example or any other learning classification model known to those skilled in the art. Step S400 is then a step of determining an area in which the device is located among a plurality of predetermined areas. The predetermined zones can correspond to opening zones, authorized or automatic, of one or more doors depending on the extent of the zone considered. One of the predetermined zones can correspond to a door locking zone or a door opening non-authorization zone for example. The use of a neural network makes it possible in particular to take into account the differences in power received by different antennas and to do triangulation to determine the area in which the device is located.

In one embodiment, the model of step S410 is a predictive model of the position of the device at the time when the last power is measured, the predictive model being obtained by learning from a data set comprising a plurality of histories of the measured powers, and for each history, the associated time intervals and a position of the device at the time when the last power is measured. The predictive model obtained by learning can be a regression model such as a neural network, a forest of decision trees or any other regression model known to those skilled in the art. The position of the device can be a position in a coordinate system or a position relative to a reference point.

In one embodiment, the position of the device includes a distance from a reference point. This reference point can for example be a reference point inside the passenger compartment of a vehicle or correspond to the location of a system antenna for example. The application of a threshold on the distance makes it possible to indirectly define a zone of proximity to the vehicle in which it is possible to open the vehicle.

In one embodiment, the position of the device also includes an angle relative to a reference direction. It is thus possible to define, depending on the angle, several zones or sub-zones in a zone close to the vehicle for example. Each zone or sub-zone can for example define an opening zone, authorized or automatic, of a particular door, of a vehicle for example.

FIG. 2 illustrates an example of application of the method for locating a device for controlling the opening of the doors of a vehicle. In the example described here, the device is a smart phone with a Bluetooth communication interface. It could also be a badge, a watch or a headset with a Bluetooth communication interface for example.

Figure 2 shows a vehicle 1 seen from above. The vehicle 1 has four side doors 21, 22, 23, 24 and a rear trunk door 25.

The vehicle 1 also includes a plurality of Bluetooth antennas, here five antennas 30, 31, 32, 33, 34, each antenna comprising a computer and an integrated memory. The vehicle 1 also includes a computer 4 configured to control the locking and unlocking of at least one door.

In the example given here, a zone ZI of proximity to the vehicle defines a zone for opening all the doors of the vehicle, either automatically when the presence of the device in this zone is detected, or manually , when the wearer of the device actuates one of the doors.

Furthermore, a zone Z0, outside the zone Z0, defines a zone for locking the doors for example or for not opening the doors.

In one embodiment, the location of the device in one of these areas can be determined either directly using a classification model, or indirectly, when the position of the device is determined by using the predictive model as described above with reference to steps S400 and S410 in particular. It will be noted that, in this example, to determine whether the device is in one of the two zones ZI or Z0 which can be defined as a function of the distance from a reference point, an antenna is sufficient. By using multiple antennas, it is possible to improve accuracy or define more complex areas.

In one embodiment, the location of the device can be obtained without using a model obtained by learning. For example, in the simple case in which the system comprises a single antenna, an a / R ² type regression function modeling the attenuation of the Bluetooth signal power as a function of the distance R of the device can be determined from the history of the powers received. It is then possible to deduce therefrom the distance of the device relative to the antenna and therefore the location of the device.

In one embodiment, the zone ZI comprises a plurality of sub-zones near each of the doors, so that each of the doors can only be opened when the device and therefore the wearer of the device is nearby from one of these doors. In this embodiment, a plurality of antennas are then necessary and the location of the device is preferably obtained using a model obtained by learning as described above.

In the example described here, the central antenna 30 is located in the passenger compartment of the vehicle and the peripheral antennas 31, 32, 33, 34 are located at the four corners of the vehicle. It is therefore possible to determine whether the device is in one of the zones ZI or Z0 or in a sub-zone near each of the doors for example.

In the embodiment described here, each of the peripheral antennas 31, 32, 33, 34 is used to measure the power received from Bluetooth signals emitted by a device such as a mobile phone equipped with a Bluetooth communication interface for example . The antenna 30 is used to detect the presence of an authorized device, for example the mobile phone of the owner of the vehicle with an authorized identifier, to establish a connection with this and to ask the device to continue to send signals comprising its identifier . The antenna 30 is also configured to activate the secondary antennas 31, 32, 33, 34 so that these measure the power received from the signals emitted by the identified mobile telephone. Each of the antennas 31, 32, 33, 34 is therefore able to communicate with the central antenna 30.

It will be noted that the antennas 31, 32, 33, 34 each include computers and that these computers can be configured to carry out some of the steps previously described, in particular steps S100 of continuous measurement of the power received on one or one plurality of channels and optionally step S210 of selecting, for each antenna, the last power measured from the powers measured on each channel of the antenna when the antenna measures the power received on a plurality of channels of a Bluetooth signal emitted by the device.

Alternatively, each antenna 31, 32, 33, 34 can send to the antenna computer 30 periodically the powers received measured on the plurality of channels and step S210 can be implemented in the computer of l antenna 30.

In the example described here, the computer of the central antenna 30 implements at least steps S220, S300 and S400 described above with reference to FIG. 1. After determining the location of the device, the computer the central antenna 30 sends location information of the device to the computer 4.

Depending on the location information received, the computer 4 can determine, either directly or indirectly as described above, whether the device is in an opening area of at least one door of the vehicle. Depending on the identified area, the computer 4 then generates a door opening command, either automatically depending on the detected area, or indirectly, when the computer also receives information according to which the or the one of the corresponding doors is activated by the wearer of the device.

Similarly, the computer 4 can determine whether the device is in a locking zone of the device and possibly generate a door closing command, if it detects the passage from an opening zone to a zone lock.

In the example described here, the computer 4 corresponds to the computer of a central controller for the openings and the starting of the vehicle.

In other embodiments, the computer 4 may correspond to the computer of the central antenna 30 and send the vehicle opening and starting signals to the central controller of the vehicle opening and closing control signals.

It will be noted that the central antenna 30 can also be used to measure the power received from a Bluetooth signal emitted by the device and to implement steps S100 and possibly S210. Furthermore, another antenna than the central antenna 30 could be used to establish a communication with the Bluetooth device considered, ask the latter to continue sending signals by which the power received by each antenna and communicate with the other antennas , especially.

Furthermore, steps S220, S300 and S400 implemented by the antenna computer 30 could also be implemented by any of the antennas 31, 32, 33, 34 or by another computer of the vehicle.

Claims (1)

Claims [Claim 1] Method for locating a device, by a system comprising at least one antenna and one computer, the method comprising the implementation by the system of the steps of: at. continuous measurement of the power received by each antenna of a Bluetooth signal emitted by a device, b. constitution of a history comprising a plurality of received powers measured by each antenna at different times, including at least the last power measured by one of the antennas, the history making it possible to obtain information concerning the trajectory of the device, and vs. determination, by the computer, from the history, of a location of the device at the time when the last power is measured. [Claim 2] The method of claim 1, further comprising: at. the determination, for each of the powers in the history, the time interval between the measurement of the power considered and the measurement of the last power measured, and b. in which the location of the device is obtained from the history of the measured powers and the associated time intervals. [Claim 3] Method according to claim 2, in which the determination of the location of the device comprises the use of a model obtained by learning from a data set comprising a plurality of histories of measured powers, and for each history, associated time intervals and at least one location information of the device in connection with the moment of acquisition of one of the measured powers of the history. [Claim 4] The method of claim 3, wherein at. determining the location of the device is a mination of an area in which the device is located among a plurality of predetermined areas, and b. the model used is a classification model obtained by ap- learning from a dataset including a plurality of histories of measured powers, and for each history, the associated time intervals and the zone in which the device is located at the time when the last power is measured. [Claim 5] The method of claim 3, wherein determining the location of the device comprises using a predictive model of the position of the device at the time when the last power is measured, the predictive model being obtained by learning from a data set comprising a plurality of histories of the measured powers, and for each history, the associated time intervals and a position of the device at the time when the last power is measured. [Claim 6] The method of claim 5, wherein the position of the device includes a distance from a reference point. [Claim 7] The method of claim 6, wherein the position of the device further includes an angle to a reference direction. [Claim 8] Method according to any one of the preceding claims, in which each antenna comprises several reception channels and in which: at. for an antenna, the continuous measurement of the received power of a Bluetooth signal emitted by the device comprises a power measurement on a plurality of channels, and b. the constitution of the history includes, for each antenna, selecting the last power measured by the antenna from among the powers measured on each antenna channel. [Claim 9] Method according to one of the preceding claims, in which the system is integrated into a vehicle comprising at least one door, the system being further configured to control the locking and unlocking of each door according to the location information of the device. . [Claim 10] Computer program product comprising code instructions for implementing a method comprising the following steps: at. reception of data from at least one antenna measuring powers received by each antenna of a [Claim 11] [Claim 12] [Claim 13] Bluetooth signal from a device, b. constitution of a history comprising a plurality of received power measured by each antenna at different times including at least the last received power measured by one of the antennas, the history making it possible to obtain information concerning the trajectory of the device, and vs. determination, from the history, of a location of the device at the time when the last power received is measured, when it is implemented by a computer. System adapted for implementing a method for locating a device according to any one of claims 1 to 9, comprising: at. at least one antenna configured to measure the power received from a Bluetooth signal emitted by a device, b. a computer configured for: i. constitute a history comprising a plurality of received powers measured by each antenna at different times including at least the last power measured by one of the antennas, the history making it possible to obtain information concerning the trajectory of the device, ii. determine, from the history, a location of the device at the time when the last power is measured. Motor vehicle comprising a system according to the preceding claim. Motor vehicle according to the preceding claim, in which the system further comprises a computer configured to control the locking and unlocking of at least one door as a function of the location information of the device.