Device for detecting movement of person by microwaves for motor vehicle

Abstract

The invention relates to a device (10) for detecting the movement of a person (2) by microwaves for a motor vehicle (1), said device (10) comprising a radiation impedance module (110) configured to be powered by a DC voltage source (30) and comprising a detection antenna (112), a MOSFET transistor (114) and an impedance matcher (116) forming a closed-loop circuit, the closed loop circuit oscillates at a predetermined fixed frequency when the circuit is powered by a voltage provided by the DC voltage source (30).

Description

[Technical field]

[0001] The present invention belongs to the field of motor vehicles, and more particularly, to an apparatus and method for detecting human movement by microwaves in a motor vehicle. [Background Technology]

[0002] It is known in motor vehicles to detect whether a hand is on a handle or a foot is near the foot of the vehicle trunk in order to unlock one or more opening elements of the vehicle.

[0003] In a first type of known solutions, this presence detection, known as "near field", is achieved using a detector typically mounted under the handle or the trunk, comprising a radar-type antenna or a capacitive sensor.

[0004] When a part of the human body (such as a hand or foot) comes within a few centimeters (e.g., less than 5 cm) of the antenna, it changes the impedance of the near-field antenna, and the analog or digital circuit of the detector can detect this change, i.e., the presence of a person.

[0005] However, for RF antennas, the detection range is limited to a few centimeters, and in particular, for most RF antennas, the detection range is limited to less than 5 centimeters. The main disadvantage of this technology is that the range for performing detection functions (such as people breaking into a vehicle) is very limited.

[0006] In a second type of known solutions, presence detection is performed using a detector implemented by a communication module installed in the vehicle and using microwaves, in particular based on BLE ( Low power consumption) or UWB (ultra-wideband) technology.

[0007] In these solutions, presence detection can be performed in the far field (e.g., up to 30 meters), but requires the use of at least two antennas: a transmitting antenna that sends waves in the form of pulses; and a receiving antenna that receives waves reflected by one or more mobile targets in the coverage area.

[0008] Detectors use the signal's time-of-flight to determine if a target is moving, which requires complex digital processing and, consequently, significant processing power and high power consumption. Furthermore, the need for multiple antennas makes the solution complex and expensive, and increases the risk of radio interference with hands-free near-field access systems, as the amount of space available for receiving access frames between each pulse is small. Finally, current standards impose power limits, which can significantly restrict the use of multiple antennas emitting microwaves or result in exceeding radio approval thresholds in communications bands, particularly in UWB.

[0009] Therefore, a simple, reliable and effective solution allowing to at least partially remedy these drawbacks would be advantageous. [Summary of the invention]

[0010] To this end, the subject of the present invention is firstly a device for detecting the movement of a person by microwaves for a motor vehicle, the device comprising: a radiation impedance module configured to be powered by a DC voltage source via a switch, the radiation impedance module comprising a detection antenna, a MOSFET transistor, and an impedance matcher forming a closed-loop circuit, the detection antenna being configured to resonate at a predetermined fixed frequency when coupled to the resonance module, emitting microwaves and receiving microwaves reflected by the person, the closed-loop circuit oscillating at the predetermined fixed frequency when powered by the voltage provided by the DC voltage source, the detection antenna being connected to the gate of the transistor, and the resistor. The anti-matching device is installed between the gate and the drain of the transistor and is configured to match the impedance of the detection antenna with the impedance of the transistor when powered by the voltage provided by the DC voltage source. The source of the transistor is configured to be connected to the ground on the one hand and to the electronic control unit on the other hand. The voltage signal transmitted by the source of the transistor represents the impedance difference of the radiation impedance module. The impedance is stable when the frequency of the wave reflected by the person is equal to the frequency of the wave emitted at the predetermined fixed frequency, indicating that there is no movement of the person, and is different when the frequency of the wave reflected by the person differs from the predetermined fixed frequency by a frequency difference greater than a threshold, indicating that movement of the person is detected.

[0011] This invention proposes a detection technique based on radiation impedance. The stability of this impedance is maintained by an impedance matcher and MOSFET transistors. In the absence of motion, the oscillator module functions as a stable transmitter / receiver / detector at a given frequency. Within the same frequency band, motion in the radiation region can cause the received frequency to shift by several hertz, disrupting the stability of its impedance. This impedance instability generates a variable leakage voltage that is easily detected at the output. Therefore, this invention proposes a simple detection strategy that does not require complex detection algorithms. The oscillator circuit at a single antenna comprises only analog components, making the device simple and low-cost, while limiting excessive power consumption compared to other far-field detection solutions. Detection using a single antenna is simple and low-cost. The detection device according to this invention can reduce high-intensity microwave emissions and comply with radio approval thresholds for communication bands. The use of analog components also limits processing to voltage signal evaluation, making it simple, efficient, reliable, and fast, particularly compared to solutions using digital processing circuits. The simple oscillator circuit arrangement limits the device size to that of a tag detector used for near-field communication (NFC). The device according to the invention can operate independently by being coupled to an electronic control unit, but the reduced size of the oscillating circuit arrangement also allows the device to be integrated into existing BLE or UWB modules, in particular by coupling the detection antenna to the communication antenna of such a module. The device according to the invention can also define pre-detection strategies in order to activate other functions, for example, triggering, preferably automatically, communication via the communication module, in particular BLE or UWB, or activating a camera, such as a dashcam or a camera for access via facial authentication. The device according to the invention is simple, low-cost and consumes very little power, which allows power consumption to be optimized, in particular when the vehicle's internal management system is in standby mode, for example when the vehicle is parked and locked. Since the impedance difference is proportional to the person's movement, the invention can also detect the type of movement made by the person, in particular in order to trigger various functions of the vehicle.

[0012] Advantageously, the device is configured to attenuate the power of the detection antenna and / or the voltage signal at the source of the transistor to a predetermined value in order to adjust the detection distance determined by the electronic control unit. Thus, a detection bubble can be generated inside and / or outside the vehicle. Such a bubble may be able to perform several functions. For example, the bubble can be placed in the center of the vehicle and its size (e.g., one meter in diameter) is set to detect an intrusion into the passenger compartment and trigger an intrusion alarm. For example again, the size of the bubble (e.g., ten meters in diameter) can be set to detect suspicious movement outside the vehicle in parking mode and activate a camera (e.g., the vehicle's dash cam) to film the vehicle's surroundings.

[0013] Preferably, the predetermined fixed frequency is greater than or equal to 2 GHz, preferably 2.45 GHz, e.g. between 2.45 GHz and 10.6 GHz, in order to use approved frequencies already used on existing smartphone type equipment operating in e.g. 4G or 5G or Ultra Wideband (UWB).

[0014] In one embodiment, the radiation impedance module includes an attenuator installed between the detection antenna and the gate of the transistor, and the attenuator is configured to attenuate the power of the detection antenna and / or the voltage signal of the source of the transistor.

[0015] In one embodiment, the radiation impedance module includes a comparator configured to compare the output voltage of the source of the transistor with a predetermined voltage threshold corresponding to the detection distance. For example, a threshold of 10 mV may correspond to an area of ​​1 m, and a threshold of 100 mV may correspond to an area of ​​5 m.

[0016] The resonance module may be integrated into the device or external to the device.

[0017] In one embodiment, the resonant module is a resonant antenna pattern, and the coupling between the detection antenna and the resonant antenna pattern is an electrical coupling. For example, placing a resonant circuit opposite or beside the detection antenna can adjust and optimize the operating frequency.

[0018] In another embodiment, the resonant module is a resonator, and the coupling between the detection antenna and the resonator is magnetic coupling. The resonator can reduce the size (radiation impedance) of the antenna while maintaining detection performance. The resonator improves detection sensitivity.

[0019] In another embodiment, the resonant module is a communication antenna of the vehicle that is external to the device, e.g. Bluetooth Low Energy (BLE) or Ultra-Wideband (UWB) type communication antennas.

[0020] The present invention also relates to a motor vehicle comprising: a detection device as described above and an electronic control unit, the electronic control unit being connected to the source of the transistor and being configured to receive the voltage signal transmitted by the source of the transistor and to detect movement around the detection device when the voltage value of the source of the transistor is greater than a predetermined threshold value.

[0021] Preferably, the electronic control unit is configured to detect a gesture based on a difference in voltage values ​​of the source of the transistor within a predetermined time period.

[0022] In one embodiment, the vehicle includes a communication antenna configured to electromagnetically couple to the detection antenna to form a resonator.

[0023] The invention also relates to a method for detecting the movement of people by microwaves in a motor vehicle, using a detection device as described above, comprising the following steps:

[0024] - microwaves resonating at a predetermined fixed frequency are emitted by the detection antenna,

[0025] - receiving the microwave reflected from said person,

[0026] - the movement of said person is detected by the electronic control unit when the absolute values ​​of the amplitudes of the voltage signals measured at the sources of the transistors differ by more than a predetermined amplitude threshold.

[0027] The present invention also relates to a computer program product, characterized in that the computer program product comprises a set of program code instructions, which, when executed by one or more processors, configure the one or more processors to implement the method as described above. [Brief Description of the Drawings]

[0028] Other features and advantages of the present invention will become more apparent upon reading the following description. This description is purely illustrative and should be read with reference to the accompanying drawings, in which:

[0029] [ Figure 1 ] Figure 1 An embodiment of a vehicle according to the invention is schematically illustrated.

[0030] [ Figure 2 ] Figure 2 Schematically illustrated is an assembly comprising a device according to the invention, which is powered by a voltage supply and delivers a signal for detecting the movement of a person.

[0031] [ Figure 3 ] Figure 3 A first embodiment of the device according to the invention is schematically illustrated.

[0032] [ Figure 4 ] Figure 4 A second embodiment of the device according to the invention is schematically illustrated.

[0033] [ Figure 5 ] Figure 5 A third embodiment of the device according to the invention is schematically illustrated.

[0034] [ Figure 6 ] Figure 6 A fourth embodiment of the device according to the invention is schematically illustrated.

[0035] [ Figure 7 ] Figure 7 A fifth embodiment of the device according to the invention is schematically illustrated.

[0036] [ Figure 8 ] Figure 8 An embodiment of the method according to the invention is schematically illustrated.

[0037] [ Figure 9 ] Figure 9 An example of a voltage signal delivered at the output of the source as a function of time for a given movement is schematically shown. [Specific implementation method]

[0038] Figure 1 An example of a motor vehicle according to the invention is schematically illustrated.

[0039] The vehicle 1 comprises a movement detection device 10 according to the present invention, an electronic control unit 20 and a DC voltage source 30 .

[0040] Testing equipment 10

[0041] refer to Figure 2 , the device 10 can detect the movement of the person 2 by microwaves, for example, in order to unlock an opening element of the vehicle 1 or trigger a communication, for example, with a smartphone of the user of the vehicle 1. The device 10 can be installed at any location in the vehicle 1, but is preferably installed at a communication module of the vehicle 1 or in the passenger compartment of the vehicle 1.

[0042] The device 10 comprises a radiation impedance module 110 which is configured to be powered by a DC voltage source 30, for example 5V.

[0043] The radiation impedance module 110 includes a detection antenna 112 , a MOSFET transistor 114 , and an impedance matcher 116 , which form an electrical loop.

[0044] The detection antenna 112 is configured to transmit microwaves ft by resonating at a predetermined fixed frequency and receive microwaves fr reflected from a person 2 located within the coverage of the transmitted microwaves ft (eg, between 50 cm and 10 m from the detection antenna 112 ).

[0045] The transistor 114 is a MOSFET type transistor and includes a gate G, a drain D, and a source S.

[0046] The detection antenna 112 is connected to the gate G of the transistor 114 .

[0047] The impedance matcher 116 is installed between the gate G and the drain D of the transistor 114 and is configured to match the impedance of the detection antenna 112 with the impedance of the transistor 114 when powered by the voltage provided by the DC voltage source 30 .

[0048] The detection antenna 112 , the transistor 114 , and the impedance matcher 116 form a closed-loop circuit that oscillates at a predetermined fixed frequency when the circuit is powered by a voltage provided by the DC voltage source 30 .

[0049] Device 10 includes a switch 120 connected between radiation impedance module 110 and DC voltage source 30. This switch 120 is periodically controlled to open and close (e.g., at a refresh rate of 10 Hz (every 100 ms)) so that power to radiation impedance module 110 is only intermittently supplied, thereby limiting the power consumption of device 10. Switch 120 is controlled by electronic control unit 20. Electronic control unit 20 sends a voltage to control switch 120. For example, if the voltage is 5 volts, the circuit is closed, and if the voltage is 0 volts, the circuit is open.

[0050] The source S of the transistor 114 is connected to the ground on one hand and to the electronic control unit 20 on the other hand. The voltage signal S (V) delivered by the source S of the transistor 114 is received by the electronic control unit 20.

[0051] The electronic control unit 20 is configured to determine the difference in amplitude of the signal S(V) delivered by the source S of the transistor 114 .

[0052] The signal S (V) transmitted from the source S of the transistor 114 is a voltage signal indicating the impedance difference of the radiation impedance module 110 .

[0053] The electronic control unit 20 is configured to determine whether the impedance of the radiation impedance module 110 is stable or different based on the voltage measured at the source S of the transistor 114. More specifically, the electronic control unit 20 is configured to determine whether the voltage at the source S of the transistor 114 is stable (i.e., substantially constant) or different (i.e., the absolute value differs by more than a threshold value).

[0054] When the frequency of microwaves fr reflected by person 2 is equal to the frequency of microwaves ft emitted at a predetermined fixed frequency, indicating that there is no movement of person 2, the voltage of the source S of transistor 114 is substantially constant, that is, the impedance of radiation impedance module 110 is stable.

[0055] On the other hand, when the frequency of the microwaves fr reflected by the person 2 differs from the predetermined fixed frequency by a frequency difference (in absolute value) greater than a threshold value (for example, between 5 and 20 Hz), indicating that the person 2 moves within the coverage of the detection antenna 112, the voltage difference at the source S of the transistor 114 exceeds the threshold value, and the impedance of the radiation impedance module 110 is different.

[0056] The electronic control unit 20 includes a processor capable of executing a set of instructions for performing these functions.

[0057] First embodiment

[0058] exist Figure 3 In the illustrated first embodiment, the vehicle 1 or the device 10 includes a resonant antenna pattern 40 , and the detection antenna 112 is electrically coupled to the resonant antenna pattern 40 to resonate.

[0059] Second embodiment

[0060] exist Figure 4 In the second embodiment shown, the vehicle 1 or the device 10 includes a resonator 45 , and the detection antenna 112 is magnetically coupled to the resonator 45 for resonance.

[0061] Third embodiment

[0062] exist Figure 5 In the third embodiment shown, the vehicle 1 includes a communication antenna 50, for example, A communication antenna of the Bluetooth Low Energy (BLE) or Ultra Wideband (UWB) type is provided, and the detection antenna 112 is electromagnetically coupled to said communication antenna 50 for resonance. The communication antenna 50 is connected to the communication module 60 to perform functions of the vehicle 1, in particular to detect the approach of a person 2 in a manner known per se and to communicate with a smartphone, a badge worn by the person 2, or a key for unlocking the vehicle 1.

[0063] Fourth embodiment

[0064] exist Figure 6 In the fourth embodiment shown, the radiation impedance module 110 includes a radio frequency attenuator 118 connected between the detection antenna 112 and the gate G of the transistor 114 .

[0065] The RF attenuator 118 may attenuate the signal received from the detection antenna 112 according to a predefined attenuation level, thereby determining the size of the detection area.

[0066] Fifth embodiment

[0067] exist Figure 7 In the illustrated fifth embodiment, the vehicle 1 includes a comparator 70 connected between the source S of the transistor 114 and the electronic control unit 20 .

[0068] The comparator 70 compares the voltage signal provided by the source S of the transistor 114 with a predetermined voltage threshold corresponding to a predefined detection distance, thereby determining the size of the detection area.

[0069] Examples of Implementation

[0070] refer to Figure 8In step E1, the switch 120 is closed to supply power to the electrical circuit of the radiation impedance module 110, and the resonance modules 40, 45, 50 resonate the detection antenna 112, so that the detection antenna 112 emits microwaves by resonating at a predetermined fixed frequency (for example, 2.45 GHz). t .

[0071] In the presence of a person 2, the microwaves f emitted by the detection antenna 112 t Reflected from the person 2, and these reflected microwaves f r Some of them are returned to the detection antenna 112 in step E2.

[0072] When the person 2 does not move in the field of the detection antenna 112, the reflected microwaves f r The impedance of the electrical circuit of the radiation impedance module 110 is not changed and remains constant, so the voltage signal S (V) delivered by the output terminal of the source S of the transistor 114 is zero.

[0073] When person 2 moves, the reflected microwaves f r The frequency of the moving target is different (the signal reflected by the moving target undergoes frequency shift, which is called the Doppler effect), which changes the impedance of the electrical circuit of the radiation impedance module 110 and generates a voltage signal S (V) transmitted at the output end of the source S of the transistor 114, and the amplitude of the voltage signal is also different.

[0074] In step E3 , the electronic control unit 20 detects said movement of said person 2 when the absolute value of the amplitude of the voltage signal S (V) measured at the source S of the transistor 114 differs by more than a predetermined amplitude threshold SAP.

[0075] Preferably, the electronic control unit 20 analyses the difference in amplitude of the received voltage signal S(V) and determines in step E4 the gesture made by the person.

[0076] Figure 9 An example of a voltage signal S (V) versus time t is shown for a movement made by a person 2. During the movement, P2 and P3 respectively show a positive frequency shift when the hand approaches the detection antenna 112 and a negative frequency shift when the hand moves away from the detection antenna. P1 and P4 represent distant points where the signal attenuates.

[0077] The present invention can detect the movement of the person 2 in a simple, cheap, fast and efficient manner by detecting the impedance change of the radiation impedance module 110 .

Claims

1. A device (10) for detecting the movement of a person (2) by microwaves for use in a motor vehicle (1), the device (10) comprising: A radiation impedance module (110) is configured to be powered by a DC voltage source (30) via a switch (120). The radiation impedance module (110) includes a detection antenna (112), a MOSFET transistor (114), and an impedance matcher (116) forming a closed-loop circuit. The detection antenna is configured to resonate at a predetermined fixed frequency, emit microwaves, and receive microwaves reflected by the person (2) when the detection antenna (112) is coupled to the resonance module (40, 50). The closed-loop circuit oscillates at the predetermined fixed frequency when the circuit is powered by a voltage provided by the DC voltage source (30). The detection antenna (112) is connected to the gate (G) of the transistor (114), and the impedance matcher (116) is installed at the gate of the transistor (114). (G) and the drain (D), and is configured to match the impedance of the detection antenna (112) with the impedance of the transistor (114) when powered by the voltage provided by the DC voltage source (30), the source (S) of the transistor (114) being configured to be connected to the ground on one hand and to the electronic control unit (20) on the other hand, the voltage signal (S (V)) transmitted by the source (S) of the transistor (114) representing the impedance difference of the radiation impedance module (110), the impedance being stable when the frequency of the wave reflected by the person (2) is equal to the frequency of the wave emitted at the predetermined fixed frequency, indicating that there is no movement of the person (2), and being different when the frequency of the wave reflected by the person (2) differs from the predetermined fixed frequency by a frequency difference greater than a threshold, indicating that movement of the person (2) is detected.

2. The device (10) according to claim 1, wherein The predetermined fixed frequency is greater than or equal to 2.45 GHz.

3. The device (10) as claimed in any one of the preceding claims, wherein The radiation impedance module (110) includes an attenuator installed between the detection antenna (112) and the gate (G) of the transistor (114), and the attenuator is configured to attenuate the power of the detection antenna (112) and / or the voltage signal (S (V)) of the source (S) of the transistor (114).

4. The device (10) as claimed in any one of the preceding claims, wherein The radiation impedance module (110) includes a comparator (70) configured to compare an output voltage of a source (S) of the transistor (114) with a predetermined voltage threshold corresponding to a detection distance.

5. The device (10) as claimed in any one of the preceding claims, wherein The resonant module is a resonant antenna pattern (40), and the coupling between the detection antenna (112) and the resonant antenna pattern (40) is an electrical coupling.

6. The device (10) according to any one of claims 1 to 4, wherein The resonance module is a resonator (45), and the coupling between the detection antenna (112) and the resonator (45) is magnetic coupling.

7. The device (10) according to any one of claims 1 to 4, wherein The resonance module is a communication antenna (50) of the vehicle (1) outside the device (10), for example, a communication antenna of the BLE or UWB type.

8. A motor vehicle (1) comprising: A detection device (10) and an electronic control unit (20) as claimed in any one of the preceding claims, the electronic control unit being connected to the source (S) of the transistor (114) and being configured to receive the voltage signal (S(V)) delivered by the source (S) of the transistor (114) and to detect movement around the device (10) when the voltage value of the source (S) of the transistor (114) is greater than a predetermined threshold value.

9. The vehicle (1) according to the preceding claim, wherein The electronic control unit (20) is configured to detect a gesture based on a difference in voltage values ​​of a source (S) of the transistor (114) within a predetermined time period.

10. A method for detecting the movement of a person (2) by microwaves for a motor vehicle (1), using a detection device (10) as claimed in any one of claims 1 to 7, the method comprising the following steps: - the detection antenna (112) emits (E1) microwaves resonating at a predetermined fixed frequency, - receiving (E2) the microwaves reflected by said person (2), - The electronic control unit (20) detects (E3) the movement of the person (2) when the absolute value of the amplitude of the voltage signal (S(V)) measured at the source (S) of the transistor (114) differs by more than a predetermined amplitude threshold (SAP).

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