Method for determining the distance between a vehicle and equipment worn by a user
The method addresses inaccuracy in signal reflection environments by using BLE channel impulse response and eigenvalue separation with quality indicators to reliably estimate distance, enhancing accuracy and safety in vehicle-user equipment interactions.
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-09-19
- Publication Date
- 2026-03-20
AI Technical Summary
Existing methods for determining the distance between a vehicle and user equipment, such as keys or phones, using Bluetooth Low Energy (BLE) and Ultra Wide Band (UWB) protocols, are inaccurate in environments with signal reflections, leading to potential safety issues and high costs.
A method involving bidirectional channel impulse response on BLE channels, eigenvalue separation, and quality indicator calculation to determine the most probable signal path and accurately estimate distance, using a combination of quality indicators to enhance reliability.
The method provides reliable and efficient distance determination between a vehicle and user equipment, minimizing errors and ensuring accurate vehicle function activation.
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Abstract
Description
Title of the invention: Method for determining the distance between a vehicle and equipment worn by a user. Technical field
[0001] The present invention relates to the automotive field and more particularly concerns a method for determining the distance between a vehicle and equipment worn by a user, as well as a vehicle implementing said method. Previous technique
[0002] It is known to determine the distance between a vehicle and equipment carried by a user, for example a key, a badge or a phone, when said user approaches said vehicle in order in particular to trigger vehicle functions such as unlocking the doors or a personalized welcome.
[0003] In one known solution, the distance can be determined by measuring the power of the signals exchanged with the user equipment. In another known solution, the distance can be determined by calculating fast Fourier transforms on the signals exchanged with the user equipment. In both cases, these solutions are not efficient in environments where the signals are reflected multiple times, such as, for example, garages or dense urban environments.
[0004] In a known solution based on the Ultra Wide Band (UWB) protocol, the time of flight of the signals is used to estimate the distance. However, here again, the accuracy drops as soon as the signals are reflected multiple times. Furthermore, equipment implementing the UWB protocol remains quite expensive.
[0005] In order to remedy at least some of these drawbacks, a known solution uses the Bluetooth Low Energy (BLE) protocol and is based on an algorithm called MUSIC for "Multiple Signal Classification".
[0006] In this algorithm, each vehicle communication module capable of communicating with the user equipment at any given time first performs a bidirectional channel impulse response on the BLE band channels with the user equipment in order to collect the phase variations of the signals. Next, a covariance matrix is calculated from the channel impulse response, and then the eigenvectors and eigenvalues of said covariance matrix, which correspond to the signal paths on the BLE channels, are determined.
[0007] The pseudo-spectrum of the covariance matrix is calculated from the eigenvectors and eigenvalues of the matrix, then the peak exhibiting the maximum amplitude is selected, this maximum corresponding to the signal whose path is most probable, which is then used to calculate the distance, the pseudo-spectrum being a function of the distance in a way known in itself.
[0008] A problem arises when another high-amplitude peak precedes the maximum. This peak, lower than the maximum, may actually correspond to the real path rather than the maximum, which may have undergone one or more reflections, thus increasing its amplitude. In this case, the calculated distance may be significantly inaccurate, preventing the vehicle's functions from activating correctly. This can lead to safety issues, particularly when user equipment is detected in an area close to the vehicle, triggering, for example, the unlocking of the doors and windows, when in reality it is further away.
[0009] A simple, reliable and effective solution that would at least partially remedy these drawbacks would therefore be particularly advantageous. Description of the invention
[0010] To this end, the invention first relates to a method for determining the distance between a communication module of a motor vehicle and a user device, said vehicle comprising a plurality of communication modules each configured to communicate with said user device, said method comprising the steps of:
[0011] - for each vehicle communication module capable of communicating with user equipment at a given time: performing a bidirectional channel impulse response on the BLE band channels with the user equipment in order to collect the phase variations of the signals, calculating a covariance matrix from the performed channel impulse response, determining the eigenvalues of said covariance matrix corresponding to the signal paths performed on the BLE channels, separating the eigenvalues into a signal group, comprising the eigenvalues whose attenuation is less than a predetermined threshold, and a noise group, comprising the eigenvalues whose attenuation is greater than said predetermined threshold, determining one or more quality indicators each characterizing the signal group with respect to the noise group,
[0012] - determination of the communication module presenting the best indicator of quality or the best combination of quality indicators,
[0013] - estimation of the distance between the determined communication module and the user equipment from the power of signals exchanged between said determined communication module and said user equipment.
[0014] The method according to the invention makes it possible to determine the most probable path of signals from the user equipment with high reliability and thus to determine the distance between the vehicle and the user equipment quickly, accurately, efficiently, and reliably. Reliability is achieved by using one or, preferably, several quality indices calculated from the signal group and the noise group of the eigenvalues.
[0015] In one embodiment, the communication module is determined from the best combination of quality indicators, said best combination of quality indicators being an average, preferably weighted, of the differences, for each type of calculated quality indicator, between the calculated quality indicator for a first communication module and the calculated quality indicator for a second communication module, the first communication module and the second communication module being the communication modules whose received signals from the user equipment are the least attenuated.
[0016] In one embodiment, the communication module is determined from the best combination of quality indicators, said best combination of quality indicators being a cumulative average, preferably weighted, of the differences, for each type of calculated quality indicator, between the calculated quality indicator for a first communication module and the calculated quality indicator for a second communication module, the first communication module and the second communication module being the communication modules whose received signals from the user equipment are the least attenuated, the average being cumulative per step between a reference point located at a detection distance, at which the user equipment was detected at a distance from the vehicle, and the vehicle.
[0017] Advantageously, a first quality indicator is equal to the difference between the lowest signal power among the signals corresponding to the eigenvalues of the signal group and the highest signal power among the signals corresponding to the eigenvalues of the noise group.
[0018] Advantageously still, a second quality indicator is equal to the ratio of the average of the powers of the signals corresponding to the eigenvalues of the signal group to the average of the powers of the signals corresponding to the eigenvalues of the noise group.
[0019] Advantageously still, a third quality indicator is equal to the ratio of the slope of the linear regression line of the powers of the signals corresponding to the eigenvalues of the signal group and the slope of the linear regression line of the powers of the signals corresponding to the eigenvalues of the noise group.
[0020] The invention also relates to a computer program product characterized in that it comprises a set of program code instructions which, when executed by one or more processors, configure the processor(s) to implement a process as described above.
[0021] The invention also relates to a motor vehicle comprising an electronic control unit and a plurality of communication modules, each configured to communicate with said user equipment, each communication module being configured to perform a bidirectional channel impulse response on the BLE band channels with the user equipment in order to collect the phase variations of the signals, the vehicle being configured to:
[0022] - calculate a covariance matrix from the channel impulse response completed
[0023] - determine the eigenvalues of said covariance matrix corresponding to signal paths taken on BLE channels,
[0024] - separate the eigenvalues into a signal group, comprising the values eigenvalues whose attenuation is below a predetermined threshold, and a noise group, comprising eigenvalues whose attenuation is above said predetermined threshold,
[0025] - determine one or more quality indicators, each characterizing the signal group versus noise group,
[0026] - determine the communication module with the best quality indicator or the best combination of quality indicators,
[0027] - estimate the distance between the determined communication module and the equipment user based on the power of signals exchanged between said specified communication module and said user equipment.
[0028] In one embodiment, the electronic control unit is configured to determine the communication module from the best combination of quality indicators, said best combination of quality indicators being an average, preferably weighted, of the differences, for each type of calculated quality indicator, between the calculated quality indicator for a first communication module and the calculated quality indicator for a second communication module, the first communication module and the second communication module being the communication modules whose received signals from the user equipment are the least attenuated.
[0029] In one embodiment, the electronic control unit is configured to determine the communication module from the best combination of quality indicators, said best combination of quality indicators being a cumulative average, preferably weighted, of the differences, for each type of calculated quality indicator, between the calculated quality indicator for a first communication module and the calculated quality indicator for a second communication module, the first communication module and the second communication module being the communication modules whose received signals from the user equipment are least attenuated, the average being cumulative per step between a reference point located at a detection distance, at which the user equipment was detected at a distance from the vehicle, and the vehicle. Brief description of the drawings
[0030] Other features and advantages of the invention will become apparent from the following description. This description is purely illustrative and should be read in conjunction with the accompanying drawings, in which:
[0031] [Fig-1] Fig. 1 schematically illustrates one embodiment of the system according to the invention.
[0032] [Fig.2] Fig.2 schematically illustrates one embodiment of the process according to the invention.
[0033] [Fig.3] Fig.3 illustrates an example of a first quality indicator.
[0034] [Fig.4] Fig.4 illustrates an example of a second quality indicator.
[0035] [Fig.5] Fig.5 illustrates an example of a third quality indicator.
[0036] [Fig.6] Fig.6 illustrates a first configuration of a user device in relation to the vehicle.
[0037] [Fig.7] Fig.7 illustrates the evolution of the first quality indicator, the second quality indicator and third quality indicator as a function of distance for the configuration of [Fig.6].
[0038] [Fig.8] Figure [Fig.8] illustrates on the left the evolution of the mean and the mean cumulative of the first quality indicator, the second quality indicator and the third quality indicator as a function of distance for the configuration of [Fig.6] and on the right the error as a function of distance.
[0039] [Fig.9] Figure [Fig.9] illustrates a second configuration of a user device in relation to the vehicle.
[0040] [Fig. 10] Figure 10 illustrates the evolution of the first quality indicator, the second quality indicator and third quality indicator as a function of distance for the configuration of [Fig.9].
[0041] [Fig. 11] Figure 11 illustrates on the left the evolution of the mean and the mean cumulative of the first quality indicator, the second quality indicator and the third quality indicator as a function of distance for the configuration of [Fig.9] and on the right the error as a function of distance.
[0042] [Fig. 12] The [Fig. 12] illustrates a third configuration of a user equipment in relation to the vehicle.
[0043] [Fig. 13] The [Fig. 13] illustrates the evolution of the first quality indicator, the second quality indicator and the third quality indicator as a function of distance for the configuration of the [Fig. 12].
[0044] [Fig. 14] The [Fig. 14] illustrates on the left the evolution of the mean and the cumulative mean of the first quality indicator, the second quality indicator and the third quality indicator as a function of distance for the configuration of the [Fig. 12] and on the right the error as a function of distance.
[0045] [Fig. 15] The [Fig. 15] illustrates a fourth configuration of a user equipment in relation to the vehicle.
[0046] [Fig. 16] The [Fig. 16] illustrates the evolution of the first quality indicator, the second quality indicator and the third quality indicator as a function of distance for the configuration of the [Fig. 15].
[0047] [Fig. 17] The [Fig. 17] illustrates on the left the evolution of the mean and the cumulative mean of the first quality indicator, the second quality indicator and the third quality indicator as a function of distance for the configuration of the [Fig. 15] and on the right the error as a function of distance.
[0048] [Fig. 18] The [Fig. 18] illustrates a fifth configuration of a user equipment in relation to the vehicle.
[0049] [Fig. 19] The [Fig. 19] illustrates the evolution of the first quality indicator, the second quality indicator and the third quality indicator as a function of distance for the configuration of the [Fig. 18].
[0050] [Fig.20] Figure [Fig.20] illustrates on the left the evolution of the mean and the mean cumulative of the first quality indicator, the second quality indicator and the third quality indicator as a function of distance for the configuration of [Fig. 18] and on the right the error as a function of distance.
[0051] [Fig.21] Fig.21 illustrates a sixth configuration of a user device in relation to the vehicle.
[0052] [Fig.22] Figure [Fig.22] illustrates the evolution of the first quality indicator, of the second quality indicator and third quality indicator as a function of distance for the configuration of [Fig.21].
[0053] [Fig.23] Figure [Fig.23] illustrates on the left the evolution of the mean and the mean cumulative of the first quality indicator, the second quality indicator and the third quality indicator as a function of distance for the configuration of [Fig.21] and on the right the error as a function of distance. Description of the implementation methods
[0054] Fig. 1 illustrates an example of a motor vehicle 1 according to the invention and a user device 2 worn by a user 3 and located at a distance D from the vehicle 1.
[0055] The vehicle 1 comprises an electronic control unit 10 and a plurality of communication modules 20, for example five communication modules 20 arranged in the corners of the vehicle 1 and in its middle, in a manner known per se.
[0056] Each communication module 20 includes a transmit-receive antenna and is configured to communicate with the user equipment 2 over a Bluetooth Low Energy (BLE) wireless communication link. BLE communication is carried out on 80 channels in a frequency band between 2.4 GHz and 2.4835 GHz.
[0057] Each communication module 20 is configured to perform, for example on command from the electronic control unit 10, a bidirectional channel impulse response on the channels of the BLE band with the user equipment 2. Such a bidirectional channel impulse response consists, on each channel of the BLE band, of transmitting signals to the user equipment 2 and receiving the signals sent in response by the user equipment 2 and then determining the phase variations between said transmitted signals and said received signals.
[0058] Each communication module 20 is configured to calculate a covariance matrix from the channel impulse response achieved by said communication module 20. Alternatively, the electronic control unit 10 can be configured, for each of the communication modules 20, to calculate a covariance matrix from the channel impulse response achieved by said communication module 20.
[0059] Each communication module 20 is configured to determine the eigenvalues VP, with reference to Figures 3 to 5, of said covariance matrix corresponding to the signal paths carried out on the BLE channels. Alternatively, the electronic control unit 10 can be configured to determine, for each of the communication modules 20, the eigenvalues VP of said covariance matrix corresponding to the signal paths carried out on the BLE channels. The determination of the eigenvalues VP is a process known per se to those skilled in the art.
[0060] Each communication module 20 is configured to separate the eigenvalues VP into a signal group GS, comprising the eigenvalues VP whose attenuation is below a predetermined threshold, and a noise group GB, comprising the eigenvalues VP whose attenuation is above said predetermined threshold. Alternatively, the electronic control unit 10 can be configured for each communication modules 20, separate the eigenvalues VP into, on the one hand, a signal group GS, comprising the eigenvalues VP whose attenuation is less than a predetermined threshold, and, on the other hand, a noise group GB, comprising the eigenvalues VP whose attenuation is greater than said predetermined threshold.
[0061] The eigenvalues VP of signal group GS correspond to the signal paths between a communication module 20 and the user equipment 2 that are most probable because their power has been only slightly attenuated during the round trip, for example because the path is direct (without reflection from an object or person) or involves few reflections from an object or person, for example, one or two reflections at most. The eigenvalues VP of noise group GB correspond to signal paths that have undergone numerous reflections, for example, more than two, or originate from third-party sources, so that the signal power has been significantly attenuated (i.e., below the predetermined threshold) and these paths are therefore not representative of the actual distance between the communication module 20 and the user equipment 2 due to the long distance they have traveled.
[0062] Each communication module 20 is configured to determine one or more quality indicators IQ1, IQ2, IQ3, each characterizing the signal group with respect to the noise group. Alternatively, the electronic control unit 10 can be configured, for each of the communication modules 20, to determine one or more quality indicators IQ1, IQ2, IQ3, each characterizing the signal group GS with respect to the noise group GB.
[0063] Figures 3 to 5 represent three examples of energy E in dB of eigenvalues VP (limited to 50 for clarity) to determine three given quality indicators IQ1, IQ2, IQ3.
[0064] A first quality indicator IQ1, an example of which is given in [Fig.3], corresponds to the difference between the lowest signal power among the signals corresponding to the eigenvalues VP of the signal group GS and the highest signal power among the signals corresponding to the eigenvalues VP of the noise group GB.
[0065] A second quality indicator IQ2, an example of which is given in [Fig.4], corresponds to the ratio of the average of the powers of the signals corresponding to the eigenvalues VP of the signal group GS to the average of the powers of the signals corresponding to the eigenvalues VP of the noise group GB.
[0066] A third quality indicator IQ3, an example of which is given in [Fig.5], corresponds to the ratio of the slope of the linear regression line of the powers of the signals corresponding to the eigenvalues VP of the signal group GS and the slope of the linear regression line of the powers of the signals corresponding to the eigenvalues VP of the noise group GB.
[0067] The electronic control unit 10 is configured to determine the communication module 20 exhibiting the best quality indicator IQ1, IQ2, IQ3 or the best combination of quality indicators IQ1, IQ2, IQ3 and to estimate the distance D between the determined communication module 20 and the user equipment 2 from the signal power exchanged between said determined communication module 20 and said user equipment 2.
[0068] Preferably, a combination of the three quality indicators IQ1, IQ2, IQ3 is used. Alternatively, a single quality indicator IQ1, IQ2, IQ3 could be used, preferably one of the first quality indicator IQ1, the second quality indicator IQ2, or the third quality indicator IQ3.
[0069] The combination of quality indicators IQ1, IQ2, IQ3 may be an average of the differences, in particular weighted according to the best performance of these quality indicators (extracted from the different characterizations in different environments), for each type of quality indicator IQ1, IQ2, IQ3 calculated, between the quality indicator IQ1, IQ2, IQ3 calculated for a first communication module 20 and the quality indicator IQ1, IQ2, IQ3 calculated for a second communication module 20, the first communication module 20 and the second communication module 20 being the communication modules 20 whose signals received from user equipment 2 are the least attenuated.
[0070] The combination of quality indicators IQ1, IQ2, IQ3 being a cumulative average of the differences, in particular weighted according to the best performance of these quality indicators (extracted from the different characterizations in different environments), for each type of quality indicator IQ1, IQ2, IQ3 calculated, between the calculated quality indicator IQ1, IQ2, IQ3 for a first communication module 20 and the calculated quality indicator IQ1, IQ2, IQ3 for a second communication module 20, the first communication module 20 and the second communication module 20 being the communication modules 20 whose signals received from user equipment 2 are the least attenuated, the average being cumulative by step between a reference point located at a detection distance, at which user equipment 2 was detected at a distance from vehicle 1, and vehicle 1.
[0071] User equipment 2 includes a processor configured to implement a set of instructions to perform the functions mentioned.
[0072] Similarly, each communication module 20 includes a processor configured to implement a set of instructions to perform the aforementioned functions.
[0073] Similarly, the electronic control unit 10 includes a processor configured to implement a set of instructions to perform the aforementioned functions.
[0074] Implementation examples
[0075] With reference to [Fig.2], in a step El1, each communication module 20 able to communicate with the user equipment 2 at a given time, i.e. being in the BLE coverage of said user equipment 20, performs a bidirectional RIC channel impulse response on the channels of the BLE band with said user equipment 2 in order to collect the phase variations of the signals.
[0076] In a step E2, each communication module 20 calculates a covariance matrix MC from the channel impulse response RIC performed and then determines in a step E3 the eigenvalues VP of said covariance matrix MC corresponding to the signal paths performed on the BLE channels.
[0077] Then, in a step E4, each communication module 20 separates the eigenvalues VP into a signal group GS, comprising the eigenvalues VP whose attenuation is less than a predetermined threshold, and a noise group GB, comprising the eigenvalues VP whose attenuation is greater than said predetermined threshold.
[0078] Then, in a step E5, each communication module 20 determines an indicator IQ1, IQ2, IQ3, or several quality indicators IQ1, IQ2, IQ3, each characterizing the signal group GS against the noise group GB.
[0079] Figure 3 illustrates an example of eigenvalue energy (in dB) as a function of said eigenvalues. In this example, a first quality indicator IQ1 corresponds to the difference between the lowest signal power among the signals corresponding to the eigenvalues VP of the signal group GS and the highest signal power among the signals corresponding to the eigenvalues VP of the noise group GB.
[0080] Figure 4 illustrates an example of eigenvalue energy as a function of said eigenvalues. In this example, a second quality indicator IQ2 corresponds to the ratio of the average Avg_1 of the powers of the signals corresponding to the eigenvalues VP of the signal group GS to the average Avg_2 of the powers of the signals corresponding to the eigenvalues VP of the noise group GB.
[0081] Figure 5 illustrates an example of eigenvalue energy as a function of said eigenvalues. In this example, a third quality indicator IQ3 corresponds to the ratio of the slope SI of the linear regression line of the powers of the signals corresponding to the eigenvalues VP of the signal group GS and the slope S2 of the linear regression line of the powers of the signals corresponding to the eigenvalues VP of the noise group GB.
[0082] Once the steps E1 to E5 have been carried out for each communication module 20 that can communicate with the user equipment 2, the electronic control unit 10 determines in a step E6 the communication module 20 that has the best quality indicator IQ1, IQ2, IQ3 or the best combination of quality indicators IQ1, IQ2, IQ3.
[0083] For example, a Comb_QI combination of quality indicators IQ1, IQ2, IQ3 can be the average of the quality indicators IQ1, IQ2, IQ3 for a given distance:
[0084] [Math.l] (.U Comb_IQ =------3--------—
[0085] where a=[3=y=l for example (or any other suitable values, for example determined empirically based on the best performance of these quality indicators, in particular extracted from the different characterizations in different environments).
[0086] For example, a Cumul_Sum combination of quality indicators IQ1, IQ2, IQ3 can be the sum of the means of the quality indicators IQ1, IQ2, IQ3 for discrete distance values in a given distance range around vehicle 1, for example between 0 and 5 m with a step of 0.5 m:
[0087] [Math.2] Cumul Sum^),, „--------------
[0088] where a=[3=y=l for example (or any other suitable values, for example determined empirically based on the best performance of these quality indicators, in particular extracted from the different characterizations in different environments).
[0089] The electronic control unit 10 finally estimates, in a step E7, the distance D between the determined communication module 20 and the user equipment 2 from the power of the signals exchanged between said determined communication module 20 and said user equipment 2. This determination being known in itself to the person skilled in the art, it will not be detailed further here.
[0090] Examples of simulations
[0091] Figures 6, 9, 12, 15, 18 and 21 illustrate six different arrangements of a user 2 equipment with respect to user 3 and vehicle 1.
[0092] In the first configuration illustrated in [Fig. 6], the user equipment 2 is held in the hand of the user 3 in the so-called "surfing" position (i.e., substantially horizontal) and is positioned at approximately 45° relative to a communication module numbered 2 and called "anchor 2", vehicle 1 comprising a communication module numbered 3 and called "anchor 3" located opposite.
[0093] With reference to [Fig.7], it appears that the first quality indicator IQ1, the second quality indicator IQ2 and the third quality indicator IQ3 are higher for anchor 2 than for anchor 3 with a precision of 100%, 100% and 88.89% respectively.
[0094] With reference to [Fig. 8], it appears that the combination Comb_QI of quality indicators IQ1, IQ2, IQ3 is positive regardless of the distance, and that the combination Cumul_Sum of quality indicators IQ1, IQ2, IQ3 increases with distance. This confirms that anchor 2 is in direct line of sight with respect to anchor 3 and should therefore be used to calculate the distance D between vehicle 1 and user equipment 2, with an accuracy of 100% and 100% respectively. Furthermore, it can be seen that the error is greater on anchor 3 than on anchor 2 ([Fig. 8], right-hand graph).
[0095] In the second configuration illustrated in [Fig.9], the user equipment 2 is held in the hand of the user 3 in the so-called "surf" position (i.e. substantially horizontal) and is positioned at approximately 90° to a communication module numbered 2 and called "anchor 2", the vehicle 1 comprising a communication module numbered 3 and called "anchor 3" located on the opposite left.
[0096] With reference to [Fig. 10], it appears that the first quality indicator IQ1, the second quality indicator IQ2 and the third quality indicator IQ3 appear to be higher for anchor 2 than for anchor 3 but with inversions of curves and a precision of 68%, 52% and 52% respectively.
[0097] With reference to [Fig. 11], it appears that the combination Comb_QI of quality indicators IQ1, IQ2, IQ3 is positive and then oscillates around zero as the distance increases, while the combination Cumul_Sum of quality indicators IQ1, IQ2, IQ3 increases with distance. This confirms that anchor 2 is in direct line of sight with respect to anchor 3 and should therefore be used to calculate the distance D between vehicle 1 and user equipment 2, with an accuracy of 60% and 100%, respectively. Furthermore, it can be seen that the MUSIC Error ([Fig. 11], right-hand graph) is greater on anchor 3 than on anchor 2 when the distance is small, and that the error on anchor 2 and the error on anchor 3 are similar at larger distances.
[0098] In the third configuration illustrated in [Fig.12], the user equipment 2 is held in the hand of the user 3 in the so-called "surf" position (i.e. substantially horizontal) and is positioned at approximately 180° relative to the anchor 2, with the anchor 3 located to the left.
[0099] With reference to [Fig. 13], it appears that the first quality indicator IQ1, the second quality indicator IQ2 and the third quality indicator IQ3 appear higher for anchor 3 than for anchor 2 except at short distances and with an accuracy of 80%, 80% and 80% respectively.
[0100] With reference to [Fig. 14], it appears that the Comb_QI combination of quality indicators IQ1, IQ2, IQ3 is negative and then positive as the distance increases, and that the Cumul_Sum combination of quality indicators IQ1, IQ2, IQ3 decreases with distance and then increases while remaining below the Comb_QI combination of quality indicators IQ1, IQ2, IQ3. This confirms that anchor 3 is in direct line of sight with respect to anchor 2 and should therefore be used to calculate the distance D between vehicle 1 and user equipment 2, with an accuracy of 80% and 100% respectively. Furthermore, the MUSIC Error is greater on anchor 2 than on anchor 3 ([Fig. 14], right-hand graph).
[0101] In the fourth configuration illustrated in [Fig.15], user equipment 2 is placed in the back pocket of user 3 and is positioned at approximately 45° to anchor 2, with anchor 3 located opposite it.
[0102] With reference to [Fig. 16], it appears that the first quality indicator IQ1, the second quality indicator IQ2 and the third quality indicator IQ3 are higher for anchor 2 than for anchor 3 with a precision of 80%, 100% and 100% respectively.
[0103] With reference to [Fig. 17], it appears that the combination Comb_QI of quality indicators IQ1, IQ2, IQ3 is positive regardless of the distance and that the combination Cumul_Sum of quality indicators IQ1, IQ2, IQ3 increases with distance, which confirms that anchor 2 is in direct line of sight with respect to anchor 3 and that it must therefore be used to calculate the distance D between vehicle 1 and user equipment 2, with an accuracy of 100% and 100% respectively. It can also be seen that the error is greater on anchor 3 than on anchor 2 ([Fig. 17], right-hand graph).
[0104] In the fifth configuration illustrated in [Fig. 18], user equipment 2 is placed in the back pocket of user 3 and is positioned at approximately 90° to anchor 2, anchor 3 is located on the opposite left.
[0105] With reference to [Fig. 19], it appears that the first quality indicator IQ1, the second quality indicator IQ2 and the third quality indicator IQ3 appear to be higher for anchor 2 than for anchor 3 but with inversions of curves and an accuracy of 92.86%, 92.86% and 78.57% respectively.
[0106] With reference to [Fig. 20], it appears that the combination Comb_QI of quality indicators IQ1, IQ2, IQ3 is positive and then oscillates around zero as the distance increases, and that the combination Cumul_Sum of quality indicators IQ1, IQ2, IQ3 increases as the distance decreases, which confirms that anchor 2 is in direct line of sight with respect to anchor 3 and should therefore be used to calculate the distance D between vehicle 1 and user equipment 2, with an accuracy of 78.6% respectively. and 100%. We also see that the error is greater on anchor 3 than on anchor 2 when the distance is small, then that the error on anchor 2 and the error on anchor 3 are similar at larger distances ([Fig.20], right graph).
[0107] In the sixth configuration illustrated in [Fig.21], user equipment 2 is placed in the back pocket of user 3 and is positioned at approximately 180° relative to anchor 2, with anchor 3 located to the left.
[0108] With reference to [Fig.22], it appears that the first quality indicator IQ1, the second quality indicator IQ2 and the third quality indicator IQ3 appear to be higher for anchor 3 than for anchor 2 except at short distances and with an accuracy of 100%, 100% and 100% respectively.
[0109] With reference to [Fig. 23], it appears that the combination Comb_QI of quality indicators IQ1, IQ2, IQ3 is negative as the distance increases, and that the combination Cumul_Sum of quality indicators IQ1, IQ2, IQ3 decreases with distance and then increases while remaining negative. This confirms that anchor 3 is in direct line of sight with respect to anchor 2 and should therefore be used to calculate the distance D between vehicle 1 and user equipment 2, with an accuracy of 100% and 100% respectively. Furthermore, it can be seen that the error is greater on anchor 2 than on anchor 3 ([Fig. 23], right-hand graph).
Claims
Demands
1. A method for determining the distance (D) between a communication module (20) of a motor vehicle (1) and a user device (2), said vehicle (1) comprising a plurality of communication modules (20) each configured to communicate with said user device (2), said method comprising the steps of: - for each communication module (20) of the vehicle capable of communicating with the user device (2) at a given time: - realization (E1) of a bidirectional channel impulse response (CIR) on the BLE band channels with the user device (2) in order to collect the phase variations of the signals, - calculation (E2) of a covariance matrix (CM) from the realized channel impulse response, - determination (E3) of the eigenvalues (VP) of said covariance matrix (CM) corresponding to the signal paths realized on the BLE channels,- separation (E4) of the eigenvalues (VP) into a signal group (GS), comprising the eigenvalues (VP) whose attenuation is below a predetermined threshold, and a noise group (GB), comprising the eigenvalues (VP) whose attenuation is above said predetermined threshold, - determination (E5) of one or more quality indicators (IQ1, IQ2, IQ3) each characterizing the signal group (GS) with respect to the noise group (GB), - determination (E6) of the communication module (20) exhibiting the best quality indicator (IQ1, IQ2, IQ3) or the best combination of quality indicators (IQ1, IQ2, IQ3), - estimation (E7) of the distance (D) between the determined communication module (20) and the user equipment (2) from the signal power exchanged between said determined communication module (20) and said user equipment (2).
2. A method according to claim 1, wherein the communication module (20) is determined from the best combination of quality indicators (IQ1, IQ2, IQ3), said best combination of quality indicators (IQ1, IQ2, IQ3) being an average (Comb_QI) of the differences, for each type of quality indicator (IQ1, IQ2, IQ3) calculated, between the quality indicator (IQ1) calculated for a first communication module (20) and the quality indicator (IQ2) calculated for a second communication module (20), the first communication module (20) and the second communication module (20) being the communication modules (20) whose signals received from the user equipment (2) are the least attenuated.
3. A method according to claim 1, wherein the communication module (20) is determined from the best combination of quality indicators (IQ1, IQ2, IQ3), said best combination of quality indicators (IQ1, IQ2, IQ3) being a cumulative average (Cumul_Sum) of the differences, for each type of calculated quality indicator (IQ1, IQ2, IQ3), between the calculated quality indicator (IQ1, IQ2, IQ3) for a first communication module (20) and the calculated quality indicator (IQ1, IQ2, IQ3) for a second communication module (20), the first and second communication modules (20) being the communication modules (20) whose received signals from the user equipment (2) are the least attenuated, the average (Cumul_Sum) being cumulative in steps between a reference point located at a detection distance, to which the user equipment (2) was detected remotely from the vehicle, and the vehicle.
4. A method according to any one of the preceding claims, wherein a first quality indicator (IQ1) is equal to the difference between the lowest signal power among the signals corresponding to the eigenvalues (VP) of the signal group (GS) and the highest signal power among the signals corresponding to the eigenvalues (VP) of the noise group (GB).
5. A method according to any one of the preceding claims, wherein a second quality indicator (IQ2) is equal to the ratio of the average of the powers of the signals corresponding to the eigenvalues (VP) of the signal group (GS) to the average of the powers of the signals corresponding to the eigenvalues (VP) of the noise group (GB).
6. A method according to any one of the preceding claims, wherein a third quality indicator (IQ3) is equal to the ratio of the slope of the linear regression line of the powers of the signals corresponding to the eigenvalues (VP) of the signal group (GS) and the slope of the linear regression line of the powers of the signals corresponding to the eigenvalues (VP) of the noise group (GB).
7. Computer program product characterized in that it comprises a set of program code instructions which, when executed by one or more processors, configure the processor(s) to implement a process according to any one of the preceding claims.
8. A motor vehicle (1) comprising an electronic control unit (10) and a plurality of communication modules (20) each configured to communicate with said user equipment (2), each communication module (20) being configured to perform a bidirectional channel impulse response (CIR) on the BLE band channels with the user equipment (2) in order to collect the phase variations of the signals, the vehicle (1) being configured to: - calculate a covariance matrix (CM) from the performed channel impulse response (CIR), - determine the eigenvalues (VP) of said covariance matrix (CM) corresponding to the signal paths performed on the BLE channels, - separate the eigenvalues (VP) into a signal group (SG), comprising the eigenvalues (VP) whose attenuation is less than a predetermined threshold, and a noise group (NG),including the eigenvalues (VP) whose attenuation is greater than the predetermined threshold, - determine one or more quality indicators (IQ1, IQ2, IQ3) each characterizing the signal group (GS) relative to the noise group (GB), - determine the communication module (20) exhibiting the best quality indicator (IQ1, IQ2, IQ3) or the best combination of quality indicators (IQ1, IQ2, IQ3), - estimate the distance (D) between the determined communication module (20) and the user equipment (2) from the signal power exchanged between said determined communication module (20) and said user equipment (2).
9. Vehicle (1) according to claim 9, wherein the electronic control unit (10) is configured to determine the communication module (20) from the best combination of quality indicators (IQ1, IQ2, IQ3), said best combination of quality indicators (IQ1, IQ2, IQ3) being an average (Comb_IQ) of the differences, for each type of calculated quality indicator (IQ1, IQ2, IQ3), between the calculated quality indicator (IQ1, IQ2, IQ3) for a first communication module (20) and the calculated quality indicator (IQ1, IQ2, IQ3) for a second communication module (20), the first communication module (20) and the second communication module (20) being the communication modules (20) whose signals received from the user equipment (2) are the least attenuated.
10. A vehicle (1) according to claim 9, wherein the electronic control unit (10) is configured to determine the communication module (20) from the best combination of quality indicators (IQ1, IQ2, IQ3), said best combination of quality indicators (IQ1, IQ2, IQ3) being a cumulative average (Cumul_Sum) of the differences, for each type of calculated quality indicator (IQ1, IQ2, IQ3), between the calculated quality indicator (IQ1, IQ2, IQ3) for a first communication module (20) and the calculated quality indicator (IQ1, IQ2, IQ3) for a second communication module (20), the first and second communication modules (20) being the communication modules (20) whose received signals from the user equipment (2) are the least attenuated, the average (Cumul_Sum) being cumulative by step between a reference point located at a detection distance,to which the user equipment (2) was detected remotely from the vehicle (1), and the vehicle (1).
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