Method for estimating the distance of an element from a vehicle

Abstract

The invention relates to a method for estimating the distance (D) of an element (5) from a vehicle (1) using a detection module (10). The method comprises, in particular, the steps implemented by the detection module (10): determining (E4) the standard deviation (σ) of the phase (φ) of signals reflected from the element for each distance index in a series of distance indices; determining (E5), in the order of the series, the first index (ISD) for which the standard deviation (σ) is less than a predetermined threshold (S) for at least a predetermined duration (Δt); and estimating (E6) the distance (D) of the element (5) from the detection module (10) using the determined index (ISD). The estimated distance (D) corresponds to the predetermined distance associated with the determined index (ISD). (See Figure 2 for abbreviations.)

Description

Title of the invention: Method for estimating the distance of an element from a vehicle Technical field

[0001] The present invention relates to the automotive field and more particularly concerns a method for estimating the distance of an element relative to a vehicle as well as a detection module implementing said method. Prior art

[0002] In a motor vehicle, it is known to offer functions based on the distance of the user of said vehicle, for example to unlock the openings, using a key, a badge or a smartphone.

[0003] Historically, the technology used was based either on radio frequency (RF) and low frequency (LF) communications between the vehicle and a key or badge, or on a capacitive sensor located on the door handles.

[0004] However, these technologies do not currently allow new functions related to location to be offered, particularly due to a lack of precision. In addition, capacitive sensor technology has operating defects linked to humidity, frost or electrical interference.

[0005] In order to partially overcome these drawbacks, Bluetooth® technology has been used to communicate between the vehicle and the user's smartphone.

[0006] However, Bluetooth® technology has drawbacks in terms of security and accuracy.

[0007] A simple, reliable and effective solution to at least partially remedy these drawbacks would therefore be advantageous. Statement of the invention

[0008] To this end, the invention firstly relates to a method for estimating the distance of an element relative to a vehicle from a detection module, said method comprising the steps, implemented by said detection module:

[0009] - transmitting at least one signal on an ultra-wideband channel towards said element,

[0010] - receiving at least one signal reflected on said element,

[0011] - determining the phase of the at least one reflected signal received for different distance index of a series of distance indexes, each index corresponding to a predetermined distance from the detection module or to a predetermined range of distances from the detection module,

[0012] - determining the standard deviation of the phase for each distance index of the distance index series,

[0013] - determination in the order of the series, of the first index for which the standard deviation is below a predetermined threshold for at least a predetermined duration,

[0014] - estimation of the distance of the element relative to the detection module from of the determined index, the estimated distance corresponding to the predetermined distance associated with the determined index.

[0015] In the present application, the term "ultra wide band" means UWB (Ultra Wide Band) technology known per se. The method according to the invention uses the "reflective" or "radar" mode ("reflective mode") of said UWB technology.

[0016] The use of the phase of the reflected signal makes it possible to materialize the signature of a user or of a user's movement. However, the use of the phase alone is not sufficient because the phase is measured using a phase-locked loop which can cause so-called "phase" noise due to variations in the frequency oscillator of said loop. Also, during phase changes of the signal representing the user or their movements at a given distance associated with one of the indexes, the standard deviation decreases below the predetermined threshold, thus confirming the real presence of the user at the distance corresponding to said index. The use of the phase and the standard deviation do not require significantly large computer processing capacities at the detection module, thus making the method fast, simple, reliable and efficient while limiting costs.

[0017] Preferably, the method comprises a step of filtering the phase signal in order to obtain a rectangular signal to improve the calculation of the standard deviation.

[0018] Preferably, the method comprises a step of filtering the standard deviation signal in order to obtain a rectangular signal to facilitate the determination in the order of the series, of the first index for which the standard deviation is less than a predetermined threshold for at least a predetermined duration.

[0019] Advantageously, the method comprises a step of determining the channel impulse response, the phase being determined from said channel impulse response. The use of the channel impulse response (Channel Impulse Response or CIR) makes it possible to easily determine the amplitude and phase of the at least one reflected signal received.

[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 method as presented previously.

[0021] The invention also relates to a detection module for estimating the distance of an element relative to a motor vehicle, said detection module being adapted to be mounted in said vehicle and to transmit and receive signals ultra wideband, said detection module being configured to:

[0022] - transmit at least one signal on an ultra-wideband channel towards said element,

[0023] - receive at least one signal reflected on said element,

[0024] - determining the phase of the at least one reflected signal received for different indices of distance from a series of distance indices, each index corresponding to a predetermined distance from the detection module,

[0025] - determine the standard deviation of the phase for each distance index in the series distance index,

[0026] - determine in the order of the series, the first index for which the standard deviation is below a predetermined threshold for at least a predetermined duration,

[0027] - estimate the distance of the element from the detection module from the determined index, the estimated distance corresponding to the predetermined distance associated with the determined index.

[0028] Preferably, the detection module is configured to filter the phase signal to obtain a rectangular signal and / or to filter the standard deviation signal to obtain a rectangular signal.

[0029] Preferably, the detection module is configured to determine the channel impulse response and to determine the phase from said channel impulse response.

[0030] The invention also relates to a motor vehicle comprising at least one detection module as presented previously.

[0031] In one embodiment, the vehicle comprises a plurality of detection modules as presented previously and an electronic control unit, each detection module being configured to send the determined index or the estimated distance to the electronic control unit at a given time, the electronic control unit being configured to locate the element from the received indexes or the received distances. Brief description of the drawings

[0032] Other characteristics and advantages of the invention will become apparent from reading the description which follows. This is purely illustrative and must be read in conjunction with the appended drawings in which:

[0033] [Fig-1] [Fig.l] schematically illustrates one embodiment of the system according to the invention.

[0034] [Fig.2] [Fig.2] schematically illustrates an embodiment of the method according to the invention.

[0035] [Fig.3]: [Fig.3] includes six graphs representing phase q> and standard deviation o for the indices 1, 7, 9, 10, 11 and 13, for a predetermined threshold S of standard deviation o of 0.8 and for a predetermined duration At, for example 200 ms thus for each graph, the envelope of the reflected signals.. Description of the embodiments

[0036] [Fig.l] illustrates an example of vehicle 1 according to the invention.

[0037] Vehicle 1

[0038] In this example, the vehicle 1 comprises six detection modules 10 and an electronic control unit 20.

[0039] Detection module 10

[0040] Each detection module 10 allows the estimation of the distance of an element relative to the vehicle 1. This element can be a person or an object. In the example of [Fig.l], the element is a user 5 of the vehicle 1.

[0041] The detection modules 10 are mounted at different locations in the vehicle 1 so that each detection module 10 can measure the distance between itself and the user 5 according to its location around the vehicle 1 or in the vehicle 1.

[0042] Each detection module 10 is configured to transmit and receive ultra-wideband signals. In particular, each detection module 10 is configured to transmit at least one signal on an ultra-wideband channel towards the user 5 and to receive one or more signals reflected on the user 5, originating from the transmitted signals.

[0043] Each detection module 10 is configured to determine the phase of the at least one received reflected signal for different distance indices of a series of distance indices, where each index corresponds to a predetermined distance from said detection module 10 or to a predetermined range of distances.

[0044] The number of distance indices for each of which the phase and the standard deviation are determined is preferably chosen so as to limit the number of calculations by each detection module 10. For example, the calculations can be carried out for less than 64 indices, for example 16 or 32 indices. Each index can for example correspond to the “tap” index of the UWB standard which corresponds to a distance increment of 15 cm (index 1 = 15 cm, index 2 = 30 cm, index 3 = 45 cm, ..., index 10 = 150 cm, ... etc.).

[0045] Preferably, each detection module 10 is configured to determine the channel impulse response and to determine the phase from said channel impulse response.

[0046] Each detection module 10 is configured to determine the standard deviation of the phase for each distance index of the series of distance indices.

[0047] Preferably, each detection module 10 is configured to filter the phase signal in order to obtain a rectangular signal and / or to filter the standard deviation signal in order to to obtain a rectangular signal.

[0048] Each detection module 10 is configured to determine in the order of the series, the first index for which the standard deviation is less than a predetermined threshold for at least a predetermined duration. This threshold may for example be predetermined as being a fraction of the range of standard deviations measured in the absence of the user 5, for example between 0 and 50%. The predetermined duration is for example advantageously greater than 50 or 100 ms for the location of the position of a user 5 in dynamics or 1 second in the context of motion detection (for example of the leg to open the trunk).

[0049] Each detection module 10 is configured to estimate the distance of the user 5 relative to the detection module 10 from the determined index. The estimated distance then corresponds to the predetermined distance or the predetermined range of distances (for example its median or average) associated with the determined index.

[0050] Preferably, each detection module 10 is configured to send the index determined at a given instant or the distance estimated at a given instant to the electronic control unit 20.

[0051] Each detection module 10 comprises a processor or a microcontroller capable of implementing a set of instructions making it possible to carry out these functions.

[0052] Electronic control unit 20

[0053] The electronic control unit 20 is configured to locate the user 5 from the received indexes or the received distances, sent by several detection modules 10.

[0054] Example of implementation

[0055] In this example, with reference to [Fig.l], the user 5 is located close to the vehicle 1 by being within the range of the signals of three of the detection modules 10. Still in this non-limiting example, with reference to [Fig.3], the number of indexes II,.. .,116 of distance for each of which the phase and the standard deviation are determined is chosen to be equal to 16.

[0056] Still with reference to [Fig.2], each detection module 10 emits in a step E1 a signal on an ultra-wideband channel around itself, in particular in the direction of the user 5. Preferably, the channels are the same for all the detection modules 10 and the signals are sent sequentially (in turn following). As for the emission in UWB reflective mode, the frequency is the same but the format of the frame is different (the preamble for example). In UWB reflective mode, the detection module 10 immediately switches to reception mode with its own emitted signal as a filter (mask).

[0057] Some of the signals emitted by the receiving modules are reflected on the user 5 then return directly or indirectly to the receiving modules. detection 10 which emitted them.

[0058] In this example, three reception modules 10 receive in a step E2 the signals reflected on the user 5.

[0059] Each reception module 10 having received at least one signal reflected on the user 5 then determines in a step E3 the phase q> of the at least one reflected signal received for the different distance indices II,.. .,116 of the series of distance indices 11,...,116, i.e. for 16 index values ​​11,...,116 in this example.

[0060] Each reception module 10 having determined the phase q> then determines in a step E4 the standard deviation o of the phase for each index II,.. .,116 of the series. An optional filtering step can be carried out on the phase signal and / or on the standard deviation signal in order to improve the determination of the index in the following step E5.

[0061] Each reception module 10 having determined the standard deviation o then determines in a step E5, in the order of the series, the first index ISD for which said standard deviation o is lower than the predetermined threshold for at least the predetermined duration At.

[0062] [Fig.3] illustrates six graphs of phase q> and standard deviation o for indices 1, 7, 9, 10, 11 and 13, for a predetermined threshold S of standard deviation o of 0.8 and for a predetermined duration At, for example 200 ms. Each graph also includes the envelope of the reflected signals. For the sake of clarity in the figures, it was not possible to represent each reflected signal.

[0063] In this example, for the first index II, the phase q> seems to materialize user 5 or a movement of user 5 (series of peaks), however the standard deviation o does not fall below the predetermined threshold S of 0.8. The same applies to indices 12 to 16 (not shown).

[0064] However, for index 17, the phase q> seems to materialize user 5 or a movement of user 5 (series of peaks) and the standard deviation o falls below the predetermined threshold S of 0.8 for a duration dt greater than the predetermined duration At of 200 ms.

[0065] Index 17 is therefore the first ISD index of the series fulfilling the conditions for detecting user 5. It will be noted that for indexes 19 and 110, the detection is confirmed, thus making it possible to determine the thickness of user 5. On the other hand, the detection conditions (standard deviation o falls below the predetermined threshold S of 0.8 for a duration dt greater than the predetermined duration At of 200 ms) are no longer met for the following indexes from index 111 onwards.

[0066] Each reception module 10 then estimates in a step E6 the distance D of the user 5 with respect to said detection module 10 from the ISD index determined by said detection module 10, the estimated distance D corresponding to the predetermined distance associated with the determined ISD index. In the example of [Fig.3], the difference between each index being 15 cm, index 17 corresponding to a distance of 105 cm, which thus corresponds to the estimated distance D.

[0067] Then, in the implementation example, each reception module 10 then sends in a step E7 either the determined index ISD or the estimated distance D to the electronic control unit 20. In the example of [Fig.l], the three detection modules 10 having received signals reflected on the user 5 involve the estimation of three distances D1, D2, D3 relative to each of them.

[0068] More generally, when the electronic control unit 20 receives indices II,.. .,116, it can itself estimate the distance D between each detection module 10 and the user 5, for example using a correspondence table.

[0069] When the electronic control unit 20 knows the distance (determined or received) between each detection module 10 (having sent an index or a distance) and the user 5, the electronic control unit 20 determines in a step E8 the location L of the user 5 by crossing the estimated distances D.

[0070] In other words, each distance D estimated by each detection module 10 defines a circle around said detection module 10, the user 5 being located at the intersection of said circles (for at least three detection modules 10 as in the example of [Fig.l]) or at one of the two intersections of said circles (for two detection modules 10).

[0071] The use of the standard deviation o to determine the index II,.. .,116 is inexpensive in terms of computer processing resources. Thus, the invention therefore makes it possible to precisely, quickly, efficiently and reliably locate an element around or in the vehicle 1.

Claims

Claims

1. Method for estimating the distance (D) of an element (5) relative to a vehicle (1) from a detection module (10), said method comprising the steps, implemented by said detection module (10): - transmitting (El) at least one signal on an ultra-wideband channel towards said element (5), - receiving (E2) at least one signal reflected on said element (5), - determining (E3) the phase (q>) of the at least one reflected signal received for different distance indices (II,.. .,116) of a series of distance indices (11,...,116), each index (11,...,116) corresponding to a predetermined distance relative to the detection module (10), - determining (E4) the standard deviation (o) of the phase (q>) for each distance index (11,...,116) of the series of indices (11,...,116) of distance, - of determination (E5) in the order of the series, of first index (ISD) for which the standard deviation (o) is less than a predetermined threshold (S) for at least a predetermined duration (At), - of estimation (E6) of the distance (D) of the element (5) relative to the detection module (10) from the determined index (ISD), the estimated distance (D) corresponding to the predetermined distance associated with the determined index (ISD).

2. A method according to claim 1, comprising a step of filtering the phase signal (q>) in order to obtain a rectangular signal.

3. A method according to any preceding claim, comprising a step of filtering the standard deviation signal (o) to obtain a rectangular signal.

4. A method according to any preceding claim, further comprising a step of determining the channel impulse response, the phase (q>) being determined from said channel impulse response.

5. 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 method according to any one of the preceding claims.

6. Detection module (10) for estimating the distance (D) of an element (5) relative to a motor vehicle (1), said module detection module (10) being adapted to be mounted in said vehicle (1) and to transmit and receive ultra-wideband signals, said detection module (10) being configured to: - transmit at least one signal on an ultra-wideband channel towards said element (5), - receive at least one signal reflected on said element (5), - determine the phase (q>) of the at least one reflected signal received for different distance indexes (11,...,116) of a series of distance indexes (11,...,116), each index (II,...,116) corresponding to a predetermined distance from the detection module (10), - determine the standard deviation (o) of the phase (q>) for each distance index (11,...,116) of the series of indexes (11,...,116) of distance, - determining in the order of the series, the first index (ISD) for which the standard deviation (o) is less than a predetermined threshold (S) for at least a predetermined duration (At), - estimating the distance (D) of the element (5) relative to the detection module (10) from the determined index (ISD), the estimated distance (D) corresponding to the predetermined distance associated with the determined index (ISD).

7. Detection module (10) according to the preceding claim, said detection module (10) being configured to filter the phase signal (q>) in order to obtain a rectangular signal and / or to filter the standard deviation signal (o) in order to obtain a rectangular signal.

8. A detection module (10) according to any one of claims 6 or 7, said detection module (10) being configured to determine the channel impulse response and to determine the phase (q>) from said channel impulse response.

9. Motor vehicle (1) comprising at least one detection module (10) according to the preceding claim.

10. Vehicle (1) according to the preceding claim, said vehicle (1) comprising a plurality of detection modules (10) according to any one of claims 6 to 8 and an electronic control unit (20), each detection module (10) being configured to send the determined index (ISD) or the estimated distance (D) to the electronic control unit (20) at a given time, the electronic control unit (20) being configured to locate the element (5) from the received indices (11,...,116) or the received distances (D).

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