Motor-vehicle computer for activating a function triggered by a gesture and for measuring the speed of the vehicle

Abstract

The invention relates to a computer (120) for a motor vehicle (1), configured to detect a movement based on a parameter of a reflected radiofrequency signal when the value of the parameter is greater than a predetermined movement threshold, to compare with a predetermined duration the time interval for which the value of the parameter is greater than the predetermined movement threshold, to determine whether the detected movement corresponds to a gesture made by a user or to a movement of the vehicle (1) in order to measure the speed of the vehicle (1), when it is determined that the detected movement corresponds to a movement of the vehicle (1), or to implement subsequent gesture-recognition steps so as to activate a function of the vehicle (1) if a predetermined gesture is recognized, when it is determined that the detected movement corresponds to a gesture made by a user.

Description

DESCRIPTION Motor vehicle computer for activating a gesture-triggered function and for measuring vehicle speed [Technical field]

[0001] The invention relates to the technical field of automobiles and more particularly concerns a computer and a system for detecting movement relative to a motor vehicle. [State of the prior art]

[0002] The speed of a moving motor vehicle is an important parameter to determine in the management of on-board systems. Therefore, the vehicle includes one or more sensors that measure speed.

[0003] Nowadays, these sensors communicate with computers, which can then implement various functions, including displaying the speed on the dashboard or regulating the speed using a cruise control.

[0004] A first operating principle of such a speed measuring sensor consists of a counter that counts the number of revolutions of a vehicle wheel. Thus, by knowing the diameter of the assembly formed by the rim and the tire, the measurement of the number of revolutions per minute makes it possible to obtain the vehicle speed under normal driving conditions.

[0005] However, this method does not take into account tire wear, which reduces the diameter of the wheels, and can therefore provide erroneous measurements over time. In addition, if the vehicle slips or skids, the wheel rotation speed is no longer linked to the vehicle speed, and in this case, this method can no longer determine the vehicle speed.

[0006] There is therefore a need for a simple and effective solution to at least partially overcome these drawbacks. [Statement of the invention]

[0007] To this end, the invention firstly relates to a computer for a motor vehicle configured to:

[0008] - detecting a movement from at least one parameter of at least one reflected radiofrequency signal when the value of said at least one parameter is greater than a predetermined movement threshold, said reflected radiofrequency signal originating from the reflection on a target of an emitted radiofrequency signal, the emitted radiofrequency signal being emitted by a transmitting and receiving device and the reflected radio frequency signal being received by said transmitting and receiving device;

[0009] - comparing to a predetermined duration the time interval during which the value of the at least one parameter is greater than said predetermined movement threshold,

[0010] - determining that the detected movement corresponds to a gesture made by a user when the value of the at least one parameter is greater than the predetermined movement threshold for a time interval less than said predetermined duration,

[0011] - determining that the detected movement corresponds to a movement of the vehicle when the value of the at least one parameter is greater than said predetermined movement threshold for a time interval greater than said predetermined duration,

[0012] - measure the speed of the vehicle from the reflected radio frequency signal, when it has been determined that the detected movement corresponds to a movement of the vehicle,

[0013] - implementing subsequent gesture recognition steps so as to activate a vehicle function if a predetermined gesture is recognized, when it has been determined that the detected movement corresponds to a gesture made by a user.

[0014] The invention is based on a system for transmitting and receiving radiofrequency signals to determine the nature of a movement detected in front of the sensor, gesture or road passing in front of the sensor, and to then perform the associated function, for example the unlocking of an opening in the case of a gesture (trunk or door) or the measurement of the speed when the vehicle is moving. The invention makes it possible in particular to use the signals from the movement sensors already existing on the vehicle to measure the speed in addition to gesture detection. The invention also makes it possible to measure the speed of the vehicle while moving without this measurement being impacted by tire wear.

[0015] Advantageously, the predetermined duration is between 1 and 3 seconds, preferably between 1.5 and 2.5 seconds, more preferably of the order of 2 seconds.

[0016] Preferably, the at least one parameter is chosen from the frequency and / or amplitude of the at least one reflected radiofrequency signal.

[0017] Advantageously, the predetermined frequency threshold for detecting movement is greater than 0.1 m / s.

[0018] Advantageously, the predetermined amplitude threshold for detecting movement is greater than 100 mV, above the noise threshold.

[0019] More preferably, the calculator is configured to determine, from the reflected radiofrequency signal, a distance between the transmitting and receiving device and a ground on which the vehicle is located. This determined distance makes it possible to confirm that the vehicle is moving relative to the road.

[0020] Preferably, the distance between the detection device and the road on which the vehicle is located is calculated from pulse-modulated radio frequency signals.

[0021] The invention also relates to a motion detection system for a motor vehicle, said system comprising:

[0022] - a transmitting and receiving device, comprising at least one radiofrequency antenna, said at least one antenna being configured to transmit at least one transmitted radiofrequency signal and to receive at least one reflected radiofrequency signal,

[0023] - a calculator as presented previously.

[0024] The system according to the invention thus comprises the elements necessary both for detecting a movement, determining its nature and triggering a function associated with a detected gesture or measuring the speed as the case may be.

[0025] In a first embodiment of the system according to the invention, the transmitting and receiving device comprises two antennas configured to transmit and receive continuously modulated radiofrequency signals. The two antennas make it possible to cover a wider area for detecting movement, in particular when it is a user gesture. Preferably, the continuously modulated radiofrequency signals are of the “Continuous Wave” (CW) type.

[0026] In a second embodiment of the system according to the invention, the transmitting and receiving device comprises an antenna configured to transmit and receive pulse-modulated radiofrequency signals. The use of pulse-modulated radiofrequency signals makes it possible to determine the distance between the vehicle and the road on which it is traveling, and also to specify the portion of the signals received for determining the speed of the vehicle. Preferably, the pulse-modulated radiofrequency signals are of the ultra-wideband or “Ultra Wide Band” (UWB) type. The advantage of pulse-modulated radiofrequency signals is to add a distance measurement in the signal processing.

[0027] In a third embodiment of the system according to the invention, the transmitting and receiving device comprises two antennas configured to transmit and receive pulse-modulated radiofrequency signals. The use of two antennas makes it possible to improve the reception of useful signals compared to noise.

[0028] In a fourth embodiment of the system according to the invention, the transmitting and receiving device comprises an antenna configured to transmit and receive continuously modulated radio frequency signals. The presence of a single antenna takes up less space and therefore offers an integration / cost advantage.

[0029] Preferably, one of the antennas of the system according to the invention is oriented in use towards the ground, at approximately 90° relative to said ground forming a horizontal plane on which the vehicle extends, and the other antenna is oriented in use towards the ground, at approximately 45° relative to said horizontal plane on which the vehicle extends and in a rearward direction relative to the vehicle in order to better detect the movements of the user while increasing the precision of the speed measurements.

[0030] The invention also relates to a motor vehicle comprising a system as described above.

[0031] The invention also relates to a method for detecting movement relative to a motor vehicle to implement a function of the vehicle (triggered by a gesture or corresponding to a measurement of the speed of the vehicle), said method, implemented by a computer as presented above, comprising the steps of:

[0032] - detecting a movement from at least one parameter of at least one reflected radiofrequency signal received from a detection device when the value of said at least one parameter is greater than a predetermined movement threshold,

[0033] - comparison of the time interval during which the value of the at least one parameter is greater than said predetermined movement threshold and the predetermined duration,

[0034] - determining that the detected movement corresponds to a gesture made by a user when the value of the at least one parameter is greater than the predetermined movement threshold for a time interval less than a predetermined duration and activating a vehicle function, or

[0035] - determining that the detected movement corresponds to a movement of the vehicle when the value of the at least one parameter is greater than said predetermined movement threshold for a time interval greater than the predetermined duration and determining the speed of the vehicle.

[0036] 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 described above.

[0037] The invention also relates to a method for detecting movement relative to a motor vehicle to implement a function of the vehicle, said method implemented by a system as presented above comprising the steps of:

[0038] - transmission of at least one radiofrequency signal emitted and reception of at least one radiofrequency signal reflected by at least one radiofrequency antenna of a transmission and reception device of the vehicle,

[0039] - detection of a movement from at least one parameter of the reflected radiofrequency signal when the value of said at least one parameter is greater than a predetermined movement threshold,

[0040] - comparison of the time interval during which the value of the at least one parameter is greater than said predetermined movement threshold and the predetermined duration,

[0041] - determining that the detected movement corresponds to a gesture made by a user when the value of the at least one parameter is greater than the predetermined movement threshold for a time interval less than a predetermined duration and activating a function of the vehicle or determining that the detected movement corresponds to a movement of the vehicle when the value of the at least one parameter is greater than said predetermined movement threshold for a time interval greater than the predetermined duration and measuring the speed of the vehicle from the reflected radiofrequency signal.

[0042] The process thus described allows the calculator to distinguish a user gesture from a movement of the vehicle relative to the ground and to proceed with the opening of an opening or the calculation of the vehicle speed. [Description of the drawings]

[0043] Other characteristics and advantages of the invention will become apparent from reading the description which follows. This description is purely illustrative and must be read in conjunction with the appended drawings in which:

[0044] [Fig 1] Figure 1 represents a schematic view of a motor vehicle comprising a gesture detection system according to a first embodiment of the invention.

[0045] [Fig 2] Figure 2 represents a schematic view of a motor vehicle comprising a gesture detection system according to a second embodiment of the invention.

[0046] [Fig 3] Figure 3 schematically represents the method of selecting the calculator module according to the invention. [Description of embodiments]

[0047] Figures 1 and 2 schematically show two examples of vehicle 1 according to the invention.

[0048] Vehicle 1

[0049] The vehicle 1 comprises a motion detection system 10 and four wheels in direct physical contact with the plane formed by the ground 2.

[0050] Vehicle 1 defines a front, on the side of the passenger compartment windshield, and a rear on the opposite side.

[0051] System 10

[0052] The system 10 comprises a transmitting and receiving device 110 and a computer 120.

[0053] Device 110

[0054] The device 110 comprises at least one radiofrequency antenna A1, A2, A3 configured to emit at least one transmitted radiofrequency signal and to receive at least one radiofrequency signal reflected on a target, for example a user or the road.

[0055] In a first embodiment shown in Figure 1, the device 110 comprises a vertical antenna A1 oriented towards the ground 2 and an inclined antenna A2 at approximately 45° towards the rear of the vehicle 1. The vertical antenna A1 is configured to emit a continuous radiofrequency signal called the first emitted continuous signal and to receive a first reflected continuous signal, corresponding to the reflection on an object of the first emitted continuous signal. The inclined antenna A2 is configured to emit a continuous radiofrequency signal called the second emitted continuous signal and to receive a second reflected continuous signal, corresponding to the reflection on a surface (for example the road or a part of a user's body) of the second emitted continuous signal.

[0056] In a second embodiment shown in Figure 2, the device 110 comprises an omnidirectional antenna A3. The omnidirectional antenna A3 is configured to transmit a pulsed radiofrequency signal called a transmitted pulsed signal and to receive a reflected pulsed signal, corresponding to the reflection on a surface of the transmitted pulsed signal.

[0057] In a third embodiment, the device 110 comprises a vertical antenna A1 and an inclined antenna A2 in the same configuration as in the first embodiment. The vertical antenna A1 and the inclined antenna A2 are configured to transmit pulsed radio frequency signals.

[0058] In a fourth embodiment, the device 110 comprises an omnidirectional antenna A3 in the same configuration as in the second embodiment but configured to emit a continuously modulated radio frequency signal.

[0059] Calculator 120

[0060] The calculator 120 is configured to detect a movement from at least one parameter, for example the frequency and / or the amplitude, of at least one reflected radiofrequency signal received from the transmission and reception device 110 when the value of said at least one parameter is greater than a predetermined movement threshold.

[0061] The calculator 120 is configured to determine that the detected movement corresponds to a gesture made by a user when the value of the at least one parameter is greater than the predetermined movement threshold for a time interval less than a predetermined duration and, in this case, to activate a function of the vehicle 1.

[0062] The calculator 120 is configured to determine that the detected movement corresponds to a movement of the vehicle 1 when the value of the at least one parameter is greater than said predetermined movement threshold for a time interval greater than the predetermined duration and, in this case, to determine (i.e. measure) the speed of the vehicle.

[0063] The computer 120 comprises at least one processor or microcontroller configured to implement these functions.

[0064] Example of implementation

[0065] The system 10 can be activated by the vehicle 1 detecting a device carried by the user (not shown), in particular a key or a badge or a smartphone programmed for this purpose. Once the system 10 is activated, the device 110 emits radio frequency signals towards the ground 2 at regular intervals and receives the radio frequency signals reflected on the ground 2.

[0066] In a step E1, the at least one radiofrequency antenna A1, A2, A3 of the device 110 emits at least one transmitted radiofrequency signal and receives at least one reflected radiofrequency signal.

[0067] In a step E2, the calculator 120 detects a movement from at least one parameter of the reflected radiofrequency signal when the value of said at least one parameter is greater than a predetermined movement threshold. For example, a movement can be detected when the frequency of the reflected radiofrequency signal is greater than 0.1 m / s MHz and / or the amplitude of the reflected radiofrequency signal is greater than 100 mV.

[0068] In a step E3, the calculator 120 compares the time interval during which the value of the at least one parameter is greater than said predetermined movement threshold to the predetermined duration.

[0069] In a step E4A, the computer 120 determines that the detected movement corresponds to a gesture made by a user when the value of the at least one parameter is greater than the predetermined movement threshold for a time interval less than the predetermined duration and activates a function of the vehicle 1 associated with said gesture, for example the unlocking of an opening of the vehicle 1, in a step E5B.

[0070] In a step E4B, the computer 120 determines that the detected movement corresponds to a movement of the vehicle 1, and not to a gesture, when the value of the at least one parameter is greater than the predetermined movement threshold for a time interval greater than the predetermined duration and then measures the speed of the vehicle 1 in a step E5B.

[0071] Two embodiments using the first two embodiments described above will now be detailed.

[0072] First embodiment

[0073] The first embodiment is based on the first embodiment described above with two continuously modulated antennas, the vertical antenna A1 and the inclined antenna A2.

[0074] In the absence of an obstacle between the vehicle 1 and the ground, the first continuous signal emitted by the vertical antenna A1 is reflected by the ground 2 and the first reflected continuous signal is received by the vertical antenna A1 of the transmission and reception device 11 and the second continuous signal emitted by the inclined antenna A2 is reflected by the ground 2 and the second reflected continuous signal is received by the inclined antenna A2 of the transmission and reception device 11 (step E1).

[0075] The first reflected continuous signal and the second reflected continuous signal received by the vertical antenna A1 and the inclined antenna A2 are transmitted to the computer 10.

[0076] The computer 120 performs processing of the received reflected radio frequency signals and compares the frequency and / or amplitude to a predetermined threshold value of frequency and / or amplitude. If the frequency and / or amplitude do not exceed the predetermined threshold value, the computer 120 does not perform any further action. If the frequency and / or amplitude exceed the predetermined threshold value, the computer 120 determines that there is a detected movement (step E2).

[0077] The computer 120 then performs an analysis based on the duration of the detected movement. More precisely, the computer 120 compares the time interval during which the frequency and / or amplitude exceed the predetermined threshold value at the predetermined duration, which is a predefined nominal duration, for example two seconds (step E3).

[0078] If the computer 120 determines that the time interval during which the frequency and / or the amplitude exceeds the predetermined threshold value is less than a nominal duration, the computer 120 considers that the movement is a gesture made by a user of the vehicle 1 (step E4A) and then activates the function associated with the gesture (step E5A), for example the opening of an opening of the vehicle 1, possibly depending on the nature of the gesture (i.e. after recognition from pre-recorded gesture signatures).

[0079] The user's gesture may, for example, consist of passing the foot between the device 110 and the ground 2. The second continuous signal emitted by the inclined antenna A2 is then reflected by the user's foot and not the ground 2. In doing so, the movement of the foot itself modifies the amplitude and frequency of the reflected radiofrequency signal and allows movement detection.

[0080] If the computer 120 determines that the time interval during which the frequency and / or the amplitude exceeds the predetermined threshold value is greater than the nominal duration, the computer 120 considers that the gesture is a movement of the vehicle 1 relative to the ground 2, i.e. that the ground 2 is in movement relative to the device 110, (step E4B) and then measures the speed of movement of the vehicle 1 (step E5B).

[0081] Preferably, the calculator 120 is based solely on the second continuous signal reflected after reflection of the second continuous signal emitted by the inclined antenna A2.

[0082] More preferably, the calculator 120 determines a so-called Doppler shift frequency denoted f dfrom the measurement of the phase shift between the second continuous signal emitted by the inclined antenna A2 and the second continuous signal reflected by the ground 2 and received by the inclined antenna A2. From the phase shift frequency thus obtained, the computer 120 can calculate the speed of the vehicle (1) according to the following formula:

[0083] [Math 1]

[0085] where fd is the offset frequency, f e is the emission frequency of the second continuous signal emitted, c is the speed of the pulsed radiofrequency signal sent.

[0086] This expression corresponds to a preferred embodiment where the angle of inclination of the inclined antenna A2 is 45°. In a variant where the angle of inclination of the inclined antenna A2, noted 0, is other than 45°, the formula used to calculate the speed of the vehicle (1) is:

[0087] [Math 2]

[0089] Second embodiment

[0090] The second embodiment is based on the second embodiment described above with an omnidirectional A3 antenna with pulse modulation.

[0091] Steps E1 to E5B are similar to the first embodiment, except that the device 110 only comprises a single antenna A3.

[0092] On the other hand, when vehicle 1 is stationary, it is sufficient to measure the flight time t v , that is to say the time which elapses between the emission of the transmitted pulse signal and the reception of the pulse signal reflected by the omnidirectional antenna A3, and to have the speed c of propagation of the transmitted pulse signal to determine the distance between the transmission and reception device 11 and the ground 2.

[0093] The distance is then calculated using the following formula:

[0094] [Math 3] [° 095 ] d = ^

[0096] Alternatively, when the tilt axis of the omnidirectional antenna A3, denoted 0, is different from 45°, the distance can be calculated according to the following formula:

[0097] [Math 4]

[0099] Calculating the distance between ground 2 and vehicle 1 allows computer 10 to ensure that the reflected pulse signal captured by omnidirectional antenna A3 has indeed been reflected by the ground.

[0100] Preferably, the computer 120 begins by performing a demodulation of the reflected pulse signal by performing an in-phase mixing and a phase quadrature mixing between the reflected pulse signal and a signal at the frequency of the transmitted pulse signal, so as to generate a signal l(t) relating to an in-phase component of the received signal and a signal Q(t) relating to a phase quadrature component of the reflected pulse signal.

[0101] Then, the computer 120 performs a time sampling step of the reflected pulse signal and results in sampled data l(ti) and Q(ti), corresponding to a time sampling of the signals l(t) and Q(t). The time sampling can be implemented downstream of the generation of the signals l(t) and Q(t), or upstream of the generation of the signals l(t) and Q(t). The sampling step is advantageously between 0.8 ns and 2 ns, for example equal to 1 ns.

[0102] Following the sampling, the computer 120 performs a step of extracting data associated with a predetermined detection zone. This extraction step makes it possible to consider only portions of the signal associated with a reflection on a surface located in said predetermined detection zone, and to avoid the effect of reflection on surfaces that are not relevant because they are located outside said detection zone.

[0103] Preferably, the computer 120 determines a so-called Doppler shift frequency denoted fd from the measurement of the phase shift between the pulse signal emitted by the omnidirectional antenna A3 and the second continuous signal reflected by the ground 2 and received by the omnidirectional antenna A3.

[0104] From the phase shift frequency thus obtained, the vehicle movement speed calculation module 123 calculates the vehicle speed (1) according to the following formula:

[0105] [Math 5]

[0107] where fd is the offset frequency, f e is the emission frequency of the second continuous signal emitted and c is the speed of the pulsed radiofrequency signal sent.

[0108] This expression corresponds to a preferred embodiment where the angle of inclination of the omnidirectional antenna A3 is 45°. In a variant where the angle of inclination of the omnidirectional antenna A3, noted 0, is different, the formula used to calculate the speed of the vehicle (1) is:

[0109] [Math 6]

[0111] The invention therefore makes it possible to trigger a function associated with a gesture or to measure the speed of the vehicle 1 depending on whether the movement detected is a gesture or the scrolling of the road.

Claims

Claims

1. Computer (120) for a motor vehicle (1), said computer (120) being configured to: - detecting a movement from at least one parameter of at least one reflected radiofrequency signal when the value of said at least one parameter is greater than a predetermined movement threshold, said reflected radiofrequency signal originating from the reflection on a target of a transmitted radiofrequency signal, the transmitted radiofrequency signal being transmitted by a transmission and reception device (110) and the reflected radiofrequency signal being received by said transmission and reception device (110); - comparing with a predetermined duration the time interval during which the value of the at least one parameter is greater than said predetermined movement threshold, - determining that the detected movement corresponds to a gesture made by a user when the value of the at least one parameter is greater than the predetermined movement threshold for a time interval less than said predetermined duration, - determining that the detected movement corresponds to a movement of the vehicle (1) when the value of the at least one parameter is greater than said predetermined movement threshold for a time interval greater than said predetermined duration, - measuring the speed of the vehicle (1) from the reflected radiofrequency signal, when it has been determined that the detected movement corresponds to a movement of the vehicle (1), - implementing subsequent gesture recognition steps so as to activate a function of the vehicle (1) if a predetermined gesture is recognized, when it has been determined that the detected movement corresponds to a gesture made by a user.

2. Calculator (120) according to claim 1, in which the at least one parameter is chosen from the frequency and / or amplitude of the at least one reflected radiofrequency signal.

3. Calculator (120) according to any one of the preceding claims, wherein said calculator (120) is configured to determine, from the reflected radiofrequency signal, a distance between the transmitting and receiving device (110) and a ground (2) on which the vehicle is located.

4. Motion detection system (10) for a motor vehicle (1), said system comprising: - a transmitting and receiving device (110), comprising at least one radiofrequency antenna (A1, A2, A3), said at least one antenna (A1, A2, A3) being configured to transmit at least one transmitted radiofrequency signal and to receive at least one reflected radiofrequency signal, - a calculator (120) according to any one of the preceding claims.

5. System (10) according to the preceding claim, in which the transmitting and receiving device (110) comprises two antennas (A1, A2) configured to transmit and receive continuously modulated radiofrequency signals.

6. The system (10) of claim 4, wherein the transmitting and receiving device (110) comprises an antenna (A3) configured to transmit and receive pulse-modulated radio frequency signals.

7. System (10) according to claim 4, wherein the transmitting and receiving device (110) comprises two antennas (A1, A2) configured to transmit and receive pulse-modulated radiofrequency signals.

8. The system (10) of claim 4, wherein the transmitting and receiving device (110) comprises an antenna (A3) configured to transmit and receive continuously modulated radio frequency signals.

9. System (10) according to any one of claims 5 or 7, wherein one of the antennas (A1) is oriented in use towards the ground, at approximately 90° relative to said ground (2) forming a horizontal plane on which the vehicle extends, and the other antenna (A2, A3) is oriented in use towards the ground (2), at approximately 45° relative to said horizontal plane on which the vehicle (1) extends and in a rearward direction relative to the vehicle (1).

10. Motor vehicle (1) comprising a system (10) according to any one of claims 4 to 9.

11. A method of detecting movement relative to a motor vehicle (1) for implementing a function, said method comprising the steps of: - transmission of at least one radiofrequency signal emitted and reception (E1) of at least one radiofrequency signal reflected by at least one radiofrequency antenna (A1, A2, A3) of a transmission and reception device (110) of the vehicle (1), - detection (E2) of a movement from at least one parameter of the reflected radiofrequency signal when the value of said at least one parameter is greater than a predetermined movement threshold, - comparison (E3) of the time interval during which the value of the at least one parameter is greater than said predetermined movement threshold and the predetermined duration, - determination (E4A) that the detected movement corresponds to a gesture made by a user when the value of the at least one parameter is greater than the predetermined movement threshold for a time interval less than a predetermined duration and activation (E5A) of a function of the vehicle (1) or determination (E4B) that the detected movement corresponds to a movement of the vehicle (1) when the value of the at least one parameter is greater than said predetermined movement threshold for a time interval greater than the predetermined duration and measurement (E5B) of the speed of the vehicle (1) from the reflected radiofrequency signal.

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