Obstacle detection system comprising two UWB modules, for a motor vehicle

Abstract

Obstacle detection system (10), intended to be mounted on a motor vehicle (1) and comprising: - a first UWB module (11), for emitting an ultra-wideband radio frequency signal, called the emitted signal (S1); - a second UWB module (12), for receiving an ultra-wideband radio frequency signal, called the received signal (S2), the received signal originating from the emitted signal and comprising a first contribution (S21) coming directly from the first UWB module (11), and a second contribution (S22) having been reflected off an obstacle (30) before reaching the second UWB module (12); and - at least one computer (13), configured to receive as input data relating to the received signal (S2), and to deduce from it time-of-flight values ​​and then the estimation of a distance (D) between the obstacle and the motor vehicle;each of the second UWB module (12) and the first UWB module (11) being further configured to perform a bidirectional exchange of radio frequency signals with a UWB badge (20), and to deduce therefrom a current value of distance to said UWB badge. Figure 1;

Description

Title of the invention: Obstacle detection system comprising two UWB modules, for a motor vehicle technical field

[0001] The invention relates to the field of automobiles and more particularly to an obstacle detection system intended to be mounted on a motor vehicle to detect obstacles located outside the vehicle.

[0002] This includes, for example, detecting obstacles as part of a driving assistance system or as part of a parking assistance system. Advantageously, it involves detecting obstacles that may be in the path of a vehicle opening when that opening is opened. State of the art

[0003] Obstacle detection systems for use on motor vehicles are known in the prior art. Such systems are based, for example, on ultrasonic, LIDAR, or RADAR technology. A transmitting and receiving module is configured to send an emitted signal (ultrasonic, light, or radio frequency) outwards from the vehicle and to receive a return signal resulting from the reflection of the emitted signal off an obstacle. Analysis of the return signal provides information about the obstacle, in particular its position.

[0004] An objective of the present invention is to provide an obstacle detection system for installation on a motor vehicle, offering improved detection performance compared to prior art systems, while ensuring minimal bulk on the motor vehicle. Description of the invention

[0005] This objective is achieved with an obstacle detection system, intended to be mounted on a motor vehicle to detect obstacles located outside the vehicle, and which comprises: - a first UWB module, configured to emit an ultra-wideband radio frequency signal, called the emitted signal, emitted in use towards the outside of the motor vehicle; - a second UWB module, configured to receive an ultra-wideband radio frequency signal, called the received signal, the received signal originating from the transmitted signal and comprising a first contribution and a second contribution, the first contribution being formed by a portion of the transmitted signal coming directly from the first module, and the second contribution being formed by a portion of the transmitted signal having been reflected off an obstacle before reaching the second UWB module; and - at least one computer, called the main computer, which can be an integral part of the second UWB module, and configured to receive input data relating to the received signal, and to deduce time-of-flight values ​​and then estimate a distance between the obstacle and the motor vehicle; each of the second UWB module and the first UWB module being further configured to perform a bidirectional exchange of ultra-wideband radio frequency signals with a UWB badge, and to determine a current value of distance to said UWB badge.

[0006] Throughout this text, the term UWB (for "ultra-wide band") refers to a low-energy, high-spectrum-width radio frequency signal. In particular, a UWB radio frequency signal is defined by a bandwidth-to-center-frequency ratio greater than or equal to 20%, or by a bandwidth of 250 MHz or more.

[0007] According to the invention, signal emission is performed by the first UWB module, and signal reception is performed by the second UWB module, which is separate from the first UWB module. Signal emission and reception thus occur at two distinct locations on the motor vehicle. This arrangement ensures that a sufficient amount of signal is consistently obtained from the reflection off the obstacle. In contrast, this is not necessarily the case when emission and reception occur at the same location, depending on the shape of the area of ​​the obstacle where the emitted signal arrives. The invention thus offers improved detection performance compared to prior art systems.

[0008] Advantageously, in use, the first UWB and the second UWB module are arranged spaced apart from each other, for example spaced at least 0.5 meters apart.

[0009] Furthermore, according to the invention, signal transmission and reception are performed using two UWB modules, which also communicate with a UWB tag to identify and locate it. Such modules are commonly deployed on motor vehicles for safe distance measurement applications. In other words, the invention reuses, by adapting them, UWB modules that are, in any case, commonly found on motor vehicles. The invention thus guarantees minimal bulk for the obstacle detection system when installed on the motor vehicle. Put another way, the invention combines two functions in one with UWB modules: a "classic" UWB function for locating a tag, in particular a smartphone, and an obstacle detection function.

[0010] Preferably, the first UWB module and the second UWB module are configured to establish bidirectional communication together, and to exchange timestamp data relating to times of transmission and / or reception of signal, and the main computer is configured to use said timestamp data to obtain said time-of-flight values.

[0011] In particular, each of the first UWB module and the second UWB module is configured to: - generate and store timestamp data relating to timestamps of signal reception and / or transmission; - to incorporate such data into a signal that it emits; and - to extract such data from a signal it receives.

[0012] The main computer is configured to calculate flight time values ​​using timestamp data generated directly at the second UWB module, but also using timestamp data generated at the first UWB module and communicated to the second UWB module. The timestamp data can relate to at least one time interval between the reception of a signal by one UWB module and the return transmission of a signal by the other UWB module. It is thus possible to accurately determine a flight time between the two UWB modules, even if their respective clocks are not perfectly synchronized.

[0013] Preferably, the first UWB module and the second UWB module are configured to establish bidirectional communication together, and to exchange timestamp data relating to times of signal transmission and / or reception, and the main computer is configured to use said timestamp data to obtain said time-of-flight values.

[0014] Advantageously, the emitted signal consists of a plurality of pulses, each pulse of the emitted signal corresponding to two respective pulses of the received signal, associated respectively with the first contribution and the second contribution, the main computer being configured to: - for each pulse of the received signal, calculate a respective time-of-flight value; - distribute the flight time values ​​into a plurality of classes, where each class is associated with a predetermined range of flight time values; and - estimate the distance between the obstacle and the motor vehicle using said distribution of flight time values.

[0015] The main computer can be configured to: - on the said distribution of flight time values, identify two populations associated respectively with the first contribution and the second contribution; - determine the time difference between the two flight time populations; and - estimate the distance between the obstacle and the motor vehicle using said time difference.

[0016] Preferably, the system includes a memory, storing a first table linking together values ​​relating to flight times and values ​​of distance between the obstacle and the motor vehicle, and the main computer is configured to estimate the distance between the obstacle and the motor vehicle using said first table.

[0017] Advantageously, the main computer is further configured to: - calculate a temporal spread of the population associated with the second contribution; - estimate the size of the obstacle, using the calculated time spread.

[0018] The system may include a memory, storing a second table linking together time spread values ​​and obstacle size values, and the main computer is configured to estimate the obstacle size using said second table.

[0019] Advantageously, the second UWB module includes an antenna array, and the main computer is configured to: - determine at least one arrival angle of the received signal, using a time offset between instants of signal reception by the different antennas of the antenna matrix; - using at least one angle of arrival of the received signal, and the estimated distance between the obstacle and the motor vehicle, determine a position of the obstacle relative to the motor vehicle.

[0020] Advantageously, the emitted signal consists of a plurality of pulses, each pulse of the emitted signal corresponding to two respective pulses of the received signal, associated respectively with the first and second contributions, the main computer being configured to: - for each pulse of the received signal, calculate a respective value of arrival angle, called elementary value of arrival angle; - distribute the elementary values ​​of the angle of arrival into a plurality of classes, where each class is associated with a predetermined interval of elementary values ​​of the angle of arrival; and - estimate an arrival angle of the second contribution of the received signal, using said distribution of elementary arrival angle values.

[0021] The main computer can be configured to: - on the said distribution of elementary values ​​of angle of arrival, identify two populations associated respectively with the first contribution and the second contribution; - determine the angular difference between the two populations of elementary values ​​of angle of arrival; and - estimate the angle of arrival of the second contribution of the received signal, using said angular deviation.

[0022] The first UWB module and the second UWB module can be interchangeable, each forming a UWB transceiver module. "Interchangeable" means that they have the same technical characteristics and functions, and differ substantially only in their location on the vehicle. In some variations, the system according to the invention comprises more than two UWB transceiver modules, for example, four.

[0023] The system may include a central computer, separate from or combined with the main computer, and configured to: - receive, from each respective of the first UWB module and the second UWB module, a current value of distance to the UWB badge; - calculate, using the aforementioned current distance values, a current position of the UWB badge relative to said motor vehicle; and - to command a locking and / or unlocking of at least one opening of the motor vehicle, depending in particular on at least one current position of the UWB badge relative to said motor vehicle.

[0024] The invention also covers a vehicle comprising a system according to the invention.

[0025] The invention also covers an obstacle detection method, implemented in an obstacle detection system according to the invention, the method comprising the following steps: - emission of the signal emitted by the first UWB module and towards the outside of the motor vehicle; - reception of the received signal, by the second UWB module, the received signal comprising a first contribution formed by a part of the emitted signal coming directly from the first UWB module, and a second contribution formed by a part of the emitted signal having been reflected on an obstacle before reaching the second UWB module; - using the main computer, calculation of time-of-flight values ​​associated with the received signal, and estimation of a distance between the obstacle and the motor vehicle from said time-of-flight values; the process further comprising the following steps, implemented within each of the second UWB module and the first UWB module: - bidirectional exchanges between a UWB badge and said first UWB module, respectively receiver; - determination of a current value of distance between the UWB badge and said first UWB module, respectively receiver. Description of the figures

[0026] 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:

[0027] [Fig-1] Fig. 1 schematically illustrates an obstacle detection system according to a first embodiment of the invention, mounted on a motor vehicle;

[0028] [Fig.2] Fig.2 schematically illustrates a distribution of flight times associated with the signal received by the second UWB module, in the system of [Fig.1];

[0029] [Fig.3A] [Fig.3A] schematically illustrates a system according to a variant of [Fig.1], in use with a small obstacle;

[0030] [Fig.3B] [Fig.3B] schematically illustrates the distribution of flight times, obtained in the use illustrated in [Fig.3A];

[0031] [Fig.4A] Fig.4A schematically illustrates the system of Fig.3A, in use with a large obstacle;

[0032] [Fig.4B] [Fig.4B] schematically illustrates the distribution of flight times, obtained in the use illustrated in [Fig.4A];

[0033] [Fig.5A] [Fig.5A] schematically illustrates a system according to a variant of [Fig.1], in use with a first angle of inclination of the axis connecting the second UWB module and the obstacle;

[0034] [Fig.5B] [Fig.5B] schematically illustrates the distribution of arrival angles, obtained in the use illustrated in [Fig.5A];

[0035] [Fig.6A] Fig.6A schematically illustrates the system of Fig.5A, in use with a second angle of inclination of the axis connecting the second UWB module and the obstacle;

[0036] [Fig.6B] [Fig.6B] schematically illustrates the distribution of arrival angles, obtained in the use illustrated in [Fig.6A];

[0037] [Fig.7] Figure [Fig.7] schematically illustrates an obstacle detection system according to a second embodiment of the invention, mounted on a motor vehicle.

[0038] Detailed description of at least one embodiment

[0039] Fig. 1 schematically illustrates an obstacle detection system 10 according to the invention, shown in use, installed on a motor vehicle 1.

[0040] In [Fig. 1], an obstacle 30 is also schematically represented. Here, but not exclusively, the obstacle 30 is located in front of a side door of the motor vehicle 1. It is an obstacle that could impede the opening of the side door if its distance from the motor vehicle 30 is too great. weak.

[0041] The obstacle detection system 10 comprises at least two UWB modules, including a first UWB module 11, and a second UWB module 12.

[0042] The obstacle detection system 10 further comprises a control unit 13, referred to as the main control unit. Here, the main control unit 13 is shown as an integral part of the second UWB module 12. Alternatively, the main control unit 13 can be arranged remotely relative to the first UWB module 11 and the second UWB module 13. For example, the main control unit 13 is part of a central module managing other vehicle functions, such as unlocking the doors and windows.

[0043] Each of the first UWB module 11 and the second UWB module 12 is configured to communicate with a UWB badge 20. This communication is bidirectional, each UWB module 11, respectively 12, being capable of both transmitting a signal towards the UWB badge 20 and receiving a signal generated by the UWB badge 20. The signals exchanged are UWB radio frequency signals. In [Fig. 1], the bidirectional communications between the UWB badge and the UWB module 11, respectively 12, are represented by arrows 21.

[0044] In use, the UWB 20 badge is worn by a user wishing to access the motor vehicle 1. It includes a memory storing an authentication code. The UWB 20 badge can be a dedicated device, or be trained by a smartphone with a dedicated application.

[0045] Bidirectional communication with the UWB 20 module allows the UWB 11 and 12 modules to identify and locate the UWB badge. In particular, each UWB 11 and 12 module is configured to calculate its current distance to the UWB 20 badge.

[0046] Combining the different distances to the UWB badge then allows, by triangulation, the determination of the position of the UWB badge 20 relative to the motor vehicle 1. The triangulation calculation is advantageously performed within a remote computer, not shown in [Fig. 1]. Each of the first and second UWB modules 11 and 12 therefore includes a communication interface (not shown), allowing data to be exchanged, preferably via a wired connection, with the remote computer.

[0047] According to the invention, the first UWB module 11 is configured to emit an emitted signal SI, represented in [Fig. 1] by a series of dashed arrows. The emitted signal SI is emitted along a cone with a wide angular opening. It is a UWB-type radio frequency signal, emitted when used outside the motor vehicle 1.

[0048] Of the rays of the emitted signal, only a portion reaches the second UWB module 12, and forms the received signal S2. The received signal S2 is therefore also a ra- UWB type difrequency.

[0049] The received signal S2 includes, at least, a first contribution S2b which corresponds to a portion of the emitted signal SI which propagated directly from the first UWB module 11 to the second UWB module 12, without passing through the obstacle 30.

[0050] In the presence of an obstacle 30, the received signal S2 also includes a second contribution S22, which corresponds to a portion of the emitted signal SI that has propagated from the first UWB module 11 to the second UWB module 12, passing through the obstacle 30.

[0051] The received signal S2 is therefore a signal partly resulting from a retroreflection on the obstacle 30. It is not a signal generated by the obstacle 30 itself, unlike signals received from the UWB badge 20.

[0052] The main computer 13 is configured to receive as input data relating to the received signal S2. This data can be formed simply by an electrical signal, resulting from the conversion of the radio frequency signal into an electrical signal.

[0053] The main computer 13 is configured to calculate time-of-flight values ​​from the input data. A time of flight refers to the time required for a radio frequency signal to propagate between two points, in particular between the first UWB 11 and the second UWB module 12, passing through the obstacle. Further details on this calculation of time-of-flight values ​​are given below.

[0054] The main computer 13 is further configured to estimate a distance D between the obstacle 30 and the motor vehicle 1 from said time-of-flight values, the notions of distance and propagation time being linked by the speed of radio frequency waves in air.

[0055] The distance estimation can be based on a distance calculation, based on an assumption regarding the position of obstacle 30 (for example, obstacle 30 forms an isosceles triangle with UWB modules 11 and 12). Alternatively, the speed estimation is based on the use of a table, relating flight time values ​​and distance values ​​D

[0056] Thus, the invention proposes adapting a system dedicated to the identification and location of a UWB badge to perform an additional obstacle detection function. The additional cost and size associated with adding this obstacle detection function are therefore minimized.

[0057] In practice, obstacle detection can be used: - during vehicle operation, to provide driving assistance; - during a vehicle maneuvering phase, to provide assistance with the maneuver, in particular a maneuver to park the vehicle; or - during the opening phase of an opening (door, or trunk), to anticipate any risk of collision between the opening and an obstacle.

[0058] The system according to the invention can be configured to emit a warning signal when the estimated position of the obstacle implies a risk of collision with the vehicle. In addition, or alternatively, the system according to the invention can be configured to issue a pilot command, adapted to avoid such a collision. For example, the pilot command is a command to stop the opening of the door after a predetermined opening angle. These additional functions are advantageously implemented by the main control unit 13, or by a separate control unit.

[0059] According to the invention, the signal detected by the second UWB module comprises two contributions S2b and S22, corresponding respectively to a signal originating directly from the first UWB module and to a signal that has first been reflected off an obstacle. The presence of these two contributions improves the accuracy and robustness of the distance estimation, as described in more detail below.

[0060] According to the invention, the first UWB module 11 and the second UWB module 12 are separate from each other and arranged in two different locations on the motor vehicle 1. They are advantageously positioned far apart, for example, at the front and rear of the vehicle. This arrangement, combined with signal transmission over a wide angular range, makes it possible to receive the signal regardless of the shape of the obstacle. In particular, even if the transmitted signal intercepts the obstacle at a corner, part of the transmitted signal is reflected back towards the second UWB module 12. This is not the case when a single UWB module (or radar) performs both the signal transmission and reception functions.

[0061] In practice, each of the first UWB 11 module and the second UWB 12 module advantageously comprises: - a transmitting and receiving unit, configured to transmit and / or receive an ultra-wideband radio frequency signal; - a timestamping unit, configured to generate and store timestamp data relating to times of signal transmission and reception by said transmission and reception unit; and - a signal processing unit, configured at least to calculate current time-of-flight values, in particular from said timestamp data.

[0062] Said signal processing unit can be further configured to calculate a current value of distance to the UWB 20 badge, from at least one current value of flight time.

[0063] Said signal processing unit may be separate from or in common with the main computer 13, for example depending on whether the main computer 13 is remote from or not the second UWB module 12.

[0064] Advantageously, the exchange of signals between the first UWB module 11 The second UWB 12 module is bidirectional. For example, the second UWB 12 module can be configured to: - send a request signal to the first UWB 11 module, intended to generate the sending of the signal emitted by the first UWB 11 module; and - receive the received signal, from said emitted signal.

[0065] According to other variants, three signals are exchanged, first between the first and second UWB modules, then between the second and first UWB modules, and then again between the first and second UWB modules.

[0066] Advantageously, each UWB module is then configured to: - generate and store timestamp data, relating to timestamps at which it emits and / or receives signals (distinguishing each pulse of the signal where appropriate, see below); - to incorporate such data into a signal that it emits; and - to extract such data from a signal it receives.

[0067] The calculation of a flight time then takes into account different timestamp data, generated at the level of the first UWB module and the second UWB module.

[0068] This timestamp data advantageously relates to at least one time interval between the reception of a signal by one UWB module and the sending of a response signal to the other UWB module. This makes it possible to determine time-of-flight values ​​accurately, even when the respective clocks of the two UWB modules are not perfectly synchronized.

[0069] In practice, the emitted signal S1 advantageously takes the form of pulse trains. In other words, the emitted signal SI advantageously consists of a plurality of pulses.

[0070] Each pulse II of the emitted signal SI corresponds to two pulses in the received signal S2: - a pulse I2i corresponding to the portion of pulse II that propagated directly from the first module UWB 11 to the second module UWB 12, without passing through obstacle 30; and - an I22 pulse corresponding to the portion of the II pulse that propagated from the first UWB 11 module to the second UWB 12 module, passing through obstacle 30.

[0071] The impulse I2i is part of the first contribution S2i as mentioned above. The impulse I22 is part of the second contribution S22 as mentioned above.

[0072] Advantageously, the main computer 13 is configured to implement the following processes: - for each pulse I2i and I22 of the received signal S2, calculate a respective time-of-flight value; - distribute the flight time values ​​into a plurality of classes, where each class is associated with a predetermined range of flight time values; and - estimate the distance D between obstacle 30 and motor vehicle 1 using said distribution of flight time values.

[0073] As detailed above, the calculation of a time of flight takes into account various timestamp data, generated at the level of the first and second UWB modules. These timestamp data are advantageously each associated with a particular pulse, at least with regard to the pulses of the received signal, received at the end of the process by the second UWB module. Other timestamp data do not necessarily distinguish the pulses from one another, and do not necessarily take into account a portion of the signal that was first reflected off an obstacle.

[0074] Figure 2 illustrates a graphical representation of the distribution of flight time values ​​in the form of a histogram. The x-axis represents flight time in units of time. The y-axis represents the cumulative number of occurrences for all received I2i and I22 pulses (normalized number). In this example, each class corresponds to an interval of one unit of time. In any case, the different classes do not overlap, even partially.

[0075] The estimation of the distance D can be based on the use of a table, linking values ​​of distance D and values ​​of flight time, and stored in a memory which is accessed by the main computer 13. The table can be obtained during a preliminary calibration step, using obstacles located at known distances.

[0076] As illustrated in [Fig.2], the distribution of flight time values ​​comprises two distinct populations PI and P2.

[0077] The PI population groups together a first set of flight times associated with the first S2i contribution as mentioned above.

[0078] The P2 population includes a second set of flight times associated with the second contribution S22 as mentioned above.

[0079] In practice, groups of flight time values ​​are sought in order to identify the two populations PI and P2.

[0080] In a first embodiment of the invention, the main computer 13 is configured to estimate the distance D, based solely on the flight times of the population P2. For example, the distance D is defined from an average value of flight time on the population P2, or a median value of flight time on the population P2, or a value of flight time associated with a maximum number of occurrences on the population P2, etc.

[0081] In a second, more advanced variant, the main computer also takes into account the flight times of the PI population to estimate the distance D.

[0082] In particular, the main computer 13 is advantageously configured to determine the time gap AT between the populations PI and P2, and to estimate the distance D on the basis of this time gap AT.

[0083] The time gap AT is equal to a difference between a first reference flight time Atl, associated with the population PI, and a second reference flight time At2, associated with the population P2.

[0084] The first and second reference flight times can each be: - a flight time associated with a maximum number of occurrences in the population considered; or - an average value of flight time over the population considered; - a median value of flight time over the population considered; etc.

[0085] Estimating the distance D based on the time difference AT is advantageously based on the use of a table, stored in memory accessed by the main computer 13, which links together values ​​of the time difference AT and values ​​of the distance D between the obstacle and the motor vehicle. The table can be obtained during a preliminary calibration step, using obstacles located at known distances.

[0086] In this second variant, the distance estimation is therefore carried out on the basis of a time difference between: - the time required for the radio frequency signal to propagate directly from the first UWB module 11 to the second UWB module 12 without passing through obstacle 30 (first S2i contribution); and - the time required for the radio frequency signal to propagate from the first UWB 11 module to the second UWB 12 module through obstacle 30 (second contribution S22).

[0087] This second variant thus makes it possible, by design, to eliminate a bias in the flight time measurements. In other words, a differential measurement is performed, making it possible to eliminate the errors inherent in the flight time measurement.

[0088] Figure 3A illustrates a system 10' according to the invention, which differs from the system in Figure 1 only in that the main computer is further configured to: - calculate a temporal spread of the population P2 associated with the second contribution; - estimate the size of the obstacle, using the calculated time spread E.

[0089] The size of the obstacle here refers to its dimension along an axis parallel to the axis connecting the UWM transmitter module and the second UWB module, in the system according to the invention.

[0090] Here again, the estimation can be based on the use of a table, linking obstacle size values ​​and time spread values, and stored in memory accessed by the main computer. The table can be obtained during a preliminary calibration step, using obstacles

[0091] In [Fig.3A], the 10' system is shown in use with a small 30' obstacle.

[0092] In [Fig.3B], the flight time histogram associated with the received signal S2 and obtained using the 10' system as illustrated in [Fig.3A] is shown, i.e. with a small 30' obstacle.

[0093] Fig. 3B shows that a small 30' obstacle is associated with a low temporal spread E of the population P2, the population P2 being associated with a reflection on the 30' obstacle, as described above.

[0094] Figure 4A shows the 10' system of Figure 3A, but this time in use with a large 30'' obstacle. The other parameters are unchanged, in particular the distance to the obstacle.

[0095] In [Fig.4B], the flight time histogram associated with the received signal S2 and obtained using the 10' system as illustrated in [Fig.4A] is shown, i.e. with a large 30'' obstacle.

[0096] Fig. 4B shows that a large 30” obstacle is associated with a strong temporal spread 'E of the population P2.

[0097] Indeed, a larger obstacle size means more optical path possibilities connecting the first UWB module and the second UWB module. More optical path possibilities imply a greater variety of measured flight times, and therefore a greater temporal spread of the P2 population.

[0098] Figure 5A illustrates a 10” system according to the invention, which differs from the system in Figure 1 only in that the second 12” UWB module includes an antenna array (not shown), and in that the main computer is further configured to: - determine at least one angle of arrival (or angle of incidence) of the received signal, using time shifts between instants of signal reception by the different antennas of the antenna matrix; - using at least one angle of arrival, and the estimated distance between the obstacle and the motor vehicle, determine a position of the obstacle 30 relative to the motor vehicle.

[0099] As is known per se, the use of a receiving antenna array makes it possible to determine the arrival angle of the received signal. This is based on measuring at least one time delay between: - an instant of reception of rays from a signal (for example, a given pulse) by one of the matrix antennas; and - an instant of reception of rays of the same signal (for example of the same given pulse), by another of the antennas of the matrix.

[0100] The position of the obstacle is determined geometrically by the main computer, based on this angle of arrival and the distance D between the motor vehicle and the obstacle. The position of the obstacle relative to the motor vehicle can thus be determined precisely, without triangulation calculations and without the need for multiple distance measurements.

[0101] In [Fig. 5A], the system 10” is shown in use with an obstacle 30 for which the angle of arrival takes a value ab

[0102] The arrival angles are defined relative to the normal to an axis A. The axis A is oriented substantially along the normal to an axis connecting the first UWB 11” module and the second UWB 12” module.

[0103] Advantageously, and as detailed above, the emitted signal SI advantageously consists of a plurality of pulses. Each pulse II of the emitted signal SI corresponds to two pulses I2i and I22 in the received signal S2, as described above.

[0104] Advantageously, the main computer is then configured to implement the following processes: - for each pulse I2i and I22 of the received signal S2, calculate a respective value of arrival angle, called elementary value of arrival angle; - distribute the elementary values ​​of the angle of arrival into a plurality of classes, where each class is associated with a predetermined interval of elementary values ​​of the angle of arrival; and - estimate the angle of arrival of the second contribution of the received signal, using the distribution of the angle of arrival values ​​of the pulses I2i and I22.

[0105] In [Fig.5B], the histogram of the elementary values ​​of arrival angle associated with the impulses I2i and I22, and obtained in the use of the 10” system illustrated in [Fig.5A] (i.e. with an obstacle located substantially with regard to the second UWB module).

[0106] On the histogram, the x-axis represents an elementary angle of arrival value, that is, the angle of arrival of a pulse. The y-axis represents the cumulative number of occurrences for all received pulses I2i and I22 (normalized number). Each class corresponds to a range of angle values. The different classes do not overlap, even partially.

[0107] As shown in [Fig.5A], the distribution of arrival angle values ​​comprises two distinct populations P'1 and P'2.

[0108] The population P' 1 groups together a first set of arrival angles, associated with the impulses I2i (here angle values ​​close to 90°, given the reference axis) (to define the angles of arrival)

[0109] The population P'2 groups a second set of arrival angles, associated with the impulses I22.

[0110] In practice, we look for groups of arrival angle values, in order to identify the two populations P' 1 and P'2.

[0111] The arrival angles being defined relative to the normal to an axis connecting the first UWB 11” module and the second UWB 12” module.

[0112] In a first embodiment, the main computer is configured to estimate the angle of arrival of the second contribution of the received signal, from the population P'2 only. For example, the angle of arrival of the second contribution of the received signal is defined as the average angle of arrival value over the population P'2, or the median angle of arrival value over the population P2, or an angle of arrival value associated with a maximum number of occurrences over the population P2.

[0113] Alternatively, the main computer also takes into account the arrival angles of population P'1 to estimate the arrival angle of the second contribution of the received signal. In particular, the main computer is then advantageously configured to determine the angular difference Aai between populations P'1 and P'2, and to deduce therefrom the arrival angle of the second contribution of the received signal.

[0114] This variant allows for an invariable and known reference axis to define the arrival angle, unlike the angle A mentioned above. Here, the reference axis is defined by the axis connecting the first 11” UWB module and the second 12” UWB module.

[0115] The angle of arrival of the second contribution of the received signal can be defined as being directly equal to the angular deviation Aab. Alternatively, this angle of arrival can be defined as being equal to Aar90°.

[0116] The angular deviation Aoq is equal to the difference between a first reference arrival angle, associated with the population P' 1, and a second reference arrival angle, associated with the population P'2.

[0117] The first and second reference arrival angles can each be: - an arrival angle associated with a maximum number of occurrences in the population considered; or - an average value of the angle of arrival, associated with the population considered; - a median value of the angle of arrival, associated with the population considered; etc.

[0118] Figure 6A shows the 10" system of Figure 5A, but this time in use with an obstacle 30 offset relative to the second UWB module. This use corresponds to an angle of arrival value a2, and an angular separation Aa2 between populations P'1 and P'2. The other parameters are unchanged, in particular the distance to the obstacle.

[0119] In [Fig. 6B], a rhistogram of the elementary arrival angle values ​​associated with the impulses I2i and I22, obtained using the 10” system illustrated in [Fig. 6A], is shown. As expected, a reduced difference is observed between populations P'1 and P'2, corresponding to a lower angular deviation value compared with the case illustrated in Figures 5A and 5B.

[0120] Although described separately, the variants of figures 3A to 4B, and of figures 5A to 6B, can be combined.

[0121] Fig. 7 finally illustrates schematically a system 100 according to the invention, which comprises a plurality of UWB modules 15 and a central computer 16.

[0122] Here, but not limited to, the system 100 comprises four UWB modules, distributed for use at the four corners of the motor vehicle 1.

[0123] Each of the UWB modules is configured to form both a first UWB module and a second UWB module as described above.

[0124] The central computer 16 may include the main computer as described above.

[0125] Calculator 16 is further configured to: - receive, from at least two of the UWB 15 modules, a current distance value to the UWB 20 badge (obtained using bidirectional communication between the respective UWB 15 module and the UWB 20 badge, as described above); - calculate, using the aforementioned current distance values, a current position of the UWB 20 badge relative to motor vehicle 1 (calculation by triangulation); and - to command a locking and / or unlocking of at least one opening of the motor vehicle 1, depending in particular on the calculated position of the UWB 20 badge.

[0126] The system 100 therefore integrates the first UWB module, the second UWB module and the main computer according to the invention. It is further configured to determine a position of the UWB badge relative to the vehicle, and to control accordingly the locking and / or unlocking of an opening of the motor vehicle 1.

[0127] The determination of a current value of distance to the UWB badge is done, in a manner known per se, using timestamp data generated at the level of said badge, and timestamp data generated at the level of a UWB module and incorporated into a signal sent by the UWB badge to the UWB module.

[0128] In variants not shown, the system 100 includes a different number of UWB 15 modules, for example two UWB 15 modules each installed on a respective B-pillar of the vehicle, or more than four UWB 15 modules installed at the four corners of the vehicle and in the center or on a B-pillar of the vehicle.

[0129] The invention also covers an obstacle detection method implemented in a system as described above, for example system 10, and comprising the following steps: - emission of the signal emitted SI, by the first UWB module 11 and towards the outside of the motor vehicle 1; - reception of the received signal S2, by the second UWB 12 module, the received signal S2 comprising a first contribution S2i formed by a part of the emitted signal coming directly from the first UWB 11 module, and a second contribution S22 formed by a part of the emitted signal having been reflected on the obstacle 30 before reaching the second UWB 12 module; - using the main computer 13, calculation of flight time values ​​associated with the received signal S2, and estimation of a distance D between the obstacle 30 and the motor vehicle 1 from said flight time values.

[0130] The method may include preliminary steps of transmitting and receiving signals, allowing time-stamping data to be obtained that is useful for time-of-flight calculations.

[0131] The process may further include the steps of: - generation and storage of timestamp data relating to times of signal transmission and / or reception, at the level of a UWB module; - transmission of this timestamp data to another of the UWB modules; and - reception of said timestamp data by said other module, and sending to the main computer for use in calculating flight time values.

[0132] In any event, the process further comprises the following steps, implemented within each of the second UWB 12 module and the first UWB 11 module: - bidirectional exchanges between the UWB 20 badge and the first UWB 11 module, respectively receiver 12; - determination of a current value of distance between the UWB badge 20 and the first UWB module 11, respectively receiver 12.

Claims

Claims

1. Obstacle detection system (10; 10'; 10”; 100), intended to be mounted on a motor vehicle (1) to detect obstacles (30; 30'; 30”) located outside the vehicle, the obstacle detection device comprising: - a first UWB module (11; 11”; 15), installed in use on the motor vehicle (1) and configured to carry out a bidirectional exchange of ultra-wideband radiofrequency signals with a UWB badge (20) such as a smartphone, and to determine a current distance value from said UWB badge, the UWB badge (20) being worn in use by a user wishing to access the motor vehicle; - a second UWB module (12; 12”; 15), installed in use on the motor vehicle (1) and configured to carry out a bidirectional exchange of ultra-wideband radiofrequency signals with said UWB badge (20), and to determine a current distance value from said UWB badge; and - a central computer, configured to: - receiving, from each respective one of the first UWB module (15) and the second UWB module (15), a current value of distance to the UWB badge (20); - calculating, using said current distance values, a current position of the UWB badge (20) relative to said motor vehicle (1); and - control locking and / or unlocking of at least one opening of the motor vehicle (1), in particular depending on at least one current position of the UWB badge relative to said motor vehicle; characterized in that: - the first UWB module (11; 11”; 15) is configured to emit an ultra-wideband radiofrequency signal, called transmitted signal (IS), emitted in use towards the exterior of the motor vehicle; - the second UWB module (12; 12”; 15) is configured to receive an ultra-wideband radiofrequency signal, called the received signal (S2), the received signal coming from the transmitted signal and comprising a first contribution (S2J coming directly from the first UWB module (11; 11”; 15) and a second contribution (S22) having been reflected on a obstacle (30; 30'; 30”) before reaching the second UWB module (12; 12”; 15); and - the system comprises at least one computer (13), called the main computer, separate from or combined with the main computer, which may be an integral part of the second UWB module, and configured to receive as input data relating to the received signal (S2), and to deduce time-of-flight values therefrom and then estimate a distance (D) between an obstacle and the motor vehicle.

2. System (10; 10'; 10”; 100) according to claim 1, characterized in that the first UWB module (11; 11”; 15) and the second UWB module (12; 12”; 15) are configured to establish together a bidirectional communication, and to exchange timestamp data relating to times of transmission and / or reception of signal, and in that the main computer is configured to use said timestamp data to obtain said time-of-flight values.

3. System (10; 10'; 10”; 100) according to claim 1 or 2, characterized in that the transmitted signal (SI) consists of a plurality of pulses, each pulse of the transmitted signal (SI) corresponding to two respective pulses of the received signal (S2), associated respectively with the first contribution (S2i) and with the second contribution (S22), the main computer (13) being configured to: - for each pulse of the received signal (S2), calculate a respective time-of-flight value; - distribute the time-of-flight values into a plurality of classes, where each class is associated with a predetermined interval of time-of-flight values; and - estimate the distance (D) between the obstacle and the motor vehicle using said distribution of time-of-flight values.

4. System (10; 10'; 10”; 100) according to any one of claims 1 to 3, characterized in that the main computer (13) is configured to: - on said distribution of flight time values, identify two populations (PI, P2) associated respectively with the first contribution and the second contribution; - determine the time difference (AT) between the two flight time populations (PI, P2); and - estimate the distance (D) between the obstacle and the motor vehicle using said time difference (AT).

5. System (10; 10'; 10”; 100) according to any one of claims 1 to 4, characterized in that it comprises a memory, storing a first table linking together values relating to flight times and distance values (D) between the obstacle and the motor vehicle, and in that the main computer (13) is configured to estimate the distance between the obstacle and the motor vehicle using said first table.

6. System (10') according to claim 4 or 5, characterized in that the main calculator is further configured to: - calculate a time spread (E; E') of the population (P2) associated with the second contribution; - estimate a size of the obstacle (30'; 30”), using the calculated time spread.

7. System (10') according to claim 6, characterized in that it comprises a memory, storing a second table linking together time spread values and obstacle size values, and in that the main computer is configured to estimate the size of the obstacle using said second table.

8. System (10”) according to any one of claims 1 to 7, characterized in that the second UWB module (12”) comprises an antenna array, and in that the main computer is configured to: - determine at least one angle of arrival (ai; a2) of the received signal, using a time shift between times of signal reception by the different antennas of the antenna array; - using the at least one angle of arrival (ai; a2) of the received signal, and the estimated distance (D) between the obstacle and the motor vehicle, determine a position of the obstacle relative to the motor vehicle.

9. System (10”) according to claim 8, characterized in that the transmitted signal consists of a plurality of pulses, each pulse of the transmitted signal corresponding to two respective pulses of the received signal, associated respectively with the first contribution and the second contribution, the main computer being configured to: - for each pulse of the received signal, calculate a respective angle of arrival value, called elementary angle of arrival value; - distribute the elementary angle of arrival values into a plurality of classes, where each class is associated with a predetermined interval of elementary angle of arrival values; and - estimate an angle of arrival (ai; a2) of the second contribution of the received signal, using said distribution of elementary values of angle of arrival.

10. System (10”) according to claim 9, characterized in that the main computer is configured to: - on said distribution of elementary values of angle of arrival, identify two populations (P' 1, P'2) associated respectively with the first contribution and with the second contribution; - determine the angular difference (Aai; Aa2) between the two populations of elementary values of angle of arrival; and - estimate the angle of arrival of the second contribution of the received signal, using said angular difference.

11. System (100) according to any one of claims 1 to 10, characterized in that the first UWB module (11; 11”; 15) and the second UWB module (12; 12”; 15) are interchangeable, and each form a UWB transmitter-receiver module.

12. Vehicle (1) comprising a system (10; 10'; 10”; 100) according to any one of claims 1 to 11.

13. Obstacle detection method, implemented in an obstacle detection system (10; 10'; 10”; 100) according to any one of claims 1 to 11, characterized in that it comprises the following steps: - transmission of the transmitted signal (SI), by the first UWB module (11; 11”; 15) and towards the outside of the motor vehicle (1); - reception of the received signal (S2), by the second UWB module (12; 12”; 15), the received signal comprising a first contribution (S2i) formed by a part of the emitted signal coming directly from the first UWB module, and a second contribution (S22) formed by a part of the emitted signal having been reflected on an obstacle before reaching the second UWB module; - using the main computer (13), calculation of time-of-flight values associated with the received signal, and estimation of a distance (D) between the obstacle (30; 30'; 30”) and the motor vehicle (1) from said time-of-flight values;the method further comprising the following steps, implemented within each of the second UWB module and the first UWB module: - bidirectional exchanges between a UWB badge (20) and said first; UWB module (11; 11'; 11”; 15), respectively receiver (12; 12'; 12”; 15); - determining a current distance value between the UWB badge (20) and said first UWB module (11; 11'; 11”; 15), respectively receiver (12; 12'; 12”; 15).

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