JP2012096668A - Method of detecting in-vehicle object to be identified - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system that can determine whether an object to be identified is positioned inside the area around a vehicle.SOLUTION: A calibration signal (S_CAL) is transmitted toward an antenna device to determine a control power (PR), a function signal (S_FONC) corresponding to the control power (PR) is transmitted toward the antenna device so that the antenna device may emit a predetermined magnetic field, and the object to be identified receives the predetermined magnetic field, measures a magnetic field (Br) corresponding to the emitted magnetic field and compares the magnetic field with a nominal magnetic field (B0). It is determined whether the object to be identified is positioned inside the area (ZO) around the antenna device in the form of being variable according to the results of the comparison.

Description

  The present invention relates to a method for detecting an identification object located in a region around an antenna device, and a detection system for executing this detection method.

  The present invention can be mainly applied to an automobile equipped with a hands-free detection system.

  According to presently known technology in this field, a method for detecting an identification object such as a badge that functions as a receiver-transmitter that checks whether it is located inside or outside a vehicle cabin. There is. If the badge is located inside the vehicle, the user is allowed to start the vehicle.

  The detection of the badge is performed using a magnetic field emitted with a constant power by adjusting the voltage of the antenna device.

  There is a problem that such a solution is difficult to put into practice. Since the voltage from the vehicle battery is supplied to the antenna device every time the voltage fluctuates (due to different operations such as starting the vehicle and stopping the engine), readjust the battery voltage. It is necessary to enable the antenna device to emit with a constant power.

  In addition, when leaving the vehicle, for example, when the door is locked and unlocked, the other door is opened to get off from another door other than the driver's door. Some doors, including the driver's seat door, cannot be locked. This is because the operation of the switch is prohibited when the other door is open.

  When this happens, forgetting to lock occurs when leaving the vehicle for a long time.

  An object of the present invention is to enable detection of an identification object by a simpler means than before.

Therefore, the present invention proposes a method for detecting an identification object in a region around an antenna device, and this method has a plurality of steps, and in these steps,
-Send calibration signal in the direction of the antenna device to determine the set power,
-Sending a function signal corresponding to the set power in the direction of the antenna device so that the antenna device emits a predetermined magnetic field;
-Measuring the magnetic field received by the identification object and corresponding to the emitted magnetic field and comparing it with the nominal magnetic field;
-Based on this comparison, it is characterized in that a determination is made as to whether the identification object is located within the area around the antenna device.

  As can be seen from the detailed description below, the identification object can be detected by calibrating the antenna device and making a comparison with the nominal magnetic field without the need for voltage adjustment. .

According to a non-limiting embodiment, the method according to the invention has the following further features:
-Calibration signals are not recognized by the identification object. Therefore, the identification target can quickly receive the subsequent function signal.

The method comprises a further step, by which
-When a calibration signal is sent, measure the current through the antenna device,
-Compare the measured current with the initial current to determine the set power.

  Thus, the calibration signal varies with easily measured current measurements.

The power is set at a voltage of a predetermined duty cycle. This adjustment is simple. Also, this adjustment can compensate for fluctuations in the power supply voltage of the antenna device.

-The voltage is a symmetric signal. As a result, even-order harmonics included in the measurement current signal can be removed, so that the current can be measured more accurately.

-The duty cycle is equal to 1/3. As a result, harmonics of orders of multiples of 3 included in the measurement current signal can be removed, so that the current can be measured more accurately.

The voltage is generated by a power stage with full-bridge or half-bridge control. As a result, a wider range of current can be obtained.

  Trigger a calibration signal based on a specific event. As a result, the calibration signal can be re-updated periodically, and as a result, the magnetic field emitted by the antenna device can be measured periodically and accurately.

-According to the first variant, the specific object is a vehicle operation. In that case, changes in the emitted magnetic field due to external events such as temperature changes can be taken into account.

-According to the second variant, the specific object is battery voltage fluctuations. Therefore, these variations can be taken into account in the calibration.

The method of the invention comprises an additional initial step of writing a fixed threshold to the identification object. Therefore, a fixed reception magnetic field can be obtained, and based on this fixed reception magnetic field, the identification object can receive a signal from the antenna device and communicate with the related control device.

-The fixed threshold varies with the nominal magnetic field. Thereby, the identification object can respond to the signal transmitted from the antenna device when the identification object is located in the region corresponding to the nominal magnetic field.

The area around the antenna device is defined by the nominal magnetic field.

-The area around the antenna device corresponds to the vehicle cabin. Therefore, it is permitted to start the vehicle by determining whether or not the identification object is located inside the passenger compartment of the vehicle.

A second object of the present invention relates to a system for detecting an identification object located in a region around an antenna device, and the system includes a control device, an antenna device, and an identification object.
-The control unit is
-Send a calibration signal in the direction of the antenna device to determine the set power,
-Sending a function signal corresponding to the set power in the direction of the antenna device so that the antenna device emits a predetermined magnetic field;
-Based on a comparison made between the magnetic field received by the identification object and the nominal magnetic field, it can be determined whether the identification object is located within the area around the antenna device;
The identification object is characterized in that it can measure the received magnetic field corresponding to the emitted magnetic field and compare it with the nominal magnetic field.

The third object of the present invention relates to an antenna device that can be interlocked with an identification object.
-Receiving a calibration signal corresponding to a predetermined initial power;
A function signal corresponding to a predetermined set power is received and a predetermined magnetic field is emitted;
A function signal can be transmitted to the identification object, the identification object receiving a magnetic field that varies with the magnetic field emitted by the antenna device;

The fourth object of the present invention relates to an antenna device and a control device capable of interlocking with an identification object, and this control device includes a signal transmitter,
-Send a calibration signal in the direction of the antenna device to determine the set power,
-A function signal corresponding to a predetermined set power is sent in the direction of the antenna device so that the antenna device emits a predetermined magnetic field.

  According to a non-limiting embodiment, the control device further comprises a signal receiver that receives the response from the identification object based on a comparison made between the received magnetic field and the nominal magnetic field.

  According to a non-limiting embodiment, the comparison is performed by identification object.

  A fifth object of the present invention is a control device configured according to any one of the above-mentioned plurality of features and an antenna device configured according to any one of the above-mentioned plurality of features. With respect to a car with a passenger cabin in place, the two devices can cooperate with an identification object.

Furthermore, as another object of the present invention,
A system (SYS) for detecting an identification object (ID) located in an area (ZO) around an antenna device (A) provided on the vehicle body, the system being a control device (DC) provided in the vehicle ), An internal antenna device (AI) provided inside the vehicle, an external antenna device (AX) provided outside the vehicle, and an identification object (ID),
-The control unit (DC)
-Send calibration signal (S_CAL) to internal and external antenna devices (AI) (AX) to determine set power (PR);
-A function signal (S_FONC) corresponding to the set power (PR) is sent to the internal and external antenna devices (AI) (AX), and the internal and external antenna devices (AI) (AX) generate a predetermined magnetic field (Be). To release,
-Based on the comparison made between the magnetic field (Br) received by the identification object (ID) and the nominal magnetic field (B0), the identification object (ID) is connected to the internal and external antenna devices (AI) (AX). It can be determined whether or not it is located within the area (ZO) (first communication area) around
The identification object (ID) can measure the received magnetic field (Br) corresponding to the emitted magnetic field (Be) and compare the received magnetic field (Br) with the nominal magnetic field (B0);
-In addition, if it is determined that the identification object (ID) is located in the area (first communication area), the locking / unlocking detector provided outside the door is locked. When it is determined that the identification object (ID) is no longer located in the area (ZO) and (first communication area) (or when a predetermined time has passed) when the door has not switched to the locked state. It is characterized by comprising a locking control device that performs switching control so that the door in the state is locked.

  In this case, when the locking operation is performed in a state where the identification object (ID) is determined to be located in the area (first communication area), the subject who owns the identification object, for example, the driver, Only when the vehicle is out of the area (the first communication area) (or when a predetermined time has passed, etc.) (if the driver gets into the car again for some reason, the locked state will not be established. The timer that counts the time is canceled), the door can be locked, and forgetting to lock can be prevented.

  Other features and advantages of the invention will be better understood from the description based on the drawings, which show non-limiting examples.

1 is a plan view of a vehicle equipped with a detection system for performing a method according to a non-limiting embodiment of the invention. FIG. 7 shows reception by an identification object detected by a method according to a non-limiting embodiment of the invention. FIG. 6 is another diagram illustrating this limit boundary corresponding to reception by an identification object detected by a method according to a non-limiting embodiment of the present invention. FIG. 3 shows a non-limiting embodiment of a method according to a non-limiting embodiment of the invention. FIG. 5 is a diagram illustrating a non-limiting embodiment of communication used between an identification object and an antenna device when using the method of FIG. 4. It is a figure which shows the frequency spectrum of the electric current which flows through an antenna apparatus and is measured when using the method of FIG. FIG. 5 is a diagram illustrating a first embodiment of a voltage signal applied to an antenna device when using the method of FIG. 4 and an associated current frequency spectrum. FIG. 5 is a diagram illustrating a second embodiment of a voltage signal applied to an antenna device when the method of FIG. 4 is implemented, and an associated current frequency spectrum. FIG. 5 is a diagram illustrating a third embodiment of a voltage signal applied to an antenna device when using the method of FIG. 4 and an associated current frequency spectrum. It is a figure which shows the mode of the magnetic field in space, and the component of this magnetic field respond | corresponds to the emitted magnetic field in the case of using the method of FIG. FIG. 5 is a current duty cycle diagram for illustrating the steps performed by the method according to FIG. 4. FIG. 5 illustrates a non-limiting embodiment of a detection system for performing the method of FIG. FIG. 13 illustrates a non-limiting embodiment of a power stage included in the detection system of FIG. FIG. 14 illustrates a non-limiting example of a voltage signal generated by the power stage of FIG. 13 and an associated current frequency spectrum. FIG. 5 is a diagram showing a current range used in the method of FIG. 4.

Detailed Description of Non-Restrictive Embodiments of the Invention FIG. 1 shows a vehicle V equipped with a transceiver device DER that transmits and receives signals used to control an antenna device A. Antenna device A includes, in this non-limiting example, a plurality of antennas, in this case an “external” antenna AX, and an “internal” antenna AI, all of which are receiver-transmitter ID and Together, these components constitute a detection system described below.

  The non-limiting example shown in the figure shows five external antennas AX, of which four antennas AX1, AX2, AX3 and AX4 are outside the cabin VH of the vehicle V, in this case The antenna AX5 is installed on the door handle, and is installed on the rear bumper VC of the vehicle. Further, the two internal antennas AI1 and AI2 are installed in the cabin VH, in this case, in the front cabin and the rear cabin of the vehicle. A low frequency alternating current is supplied to each antenna by a transceiver device DER, in which each of the antennas emits a magnetic field Be denoted as BeI and an external antenna as BeX.

  Whether the receiver-transmitter ID is located in the vicinity of the vehicle V using the external magnetic field Be as a means and the external antenna AX, in a non-limiting example, less than 1.5 m And the internal antenna AI can be used to detect whether the receiver-transmitter ID is located inside the passenger compartment VH of the vehicle.

  In this case, the receiver-transmitter ID is, in a non-limiting example, an identification object ID carried by the user of the vehicle V, such as a badge, a key, or a key fob. An example of an identification badge is given as an example in the following description.

  Utilizing the alternating current, antenna A transmits data by sending a low frequency signal BF to communicate with the badge ID, which responds by sending a radio frequency signal RF. In a non-limiting example, the low frequency signal BF is in the region of 125 kHz and the radio frequency signal RF is in the region of 433 MHz. Depending on the frequency of the low frequency signal BF down to 20 kHz or the frequency band available in various countries (315 MHz in Asia, 868 MHz in certain European countries, or 915 MHz in the USA, etc.), the radio frequency signal RF Can be raised to a high frequency of gigahertz.

  Based on the response, antenna A authenticates the badge ID and determines whether to open the vehicle door or whether to authenticate the badge ID and start the vehicle. In a non-limiting example, to authenticate the badge ID and open the door, the user needs to touch, for example, a door handle. For this purpose, the handle is equipped with a suitable detector.

  The external antenna AX determines the first communication area with the badge ID and permits operation of the vehicle. This region is defined by the magnetic field emitted from the antenna AX. Therefore, it is necessary to guarantee the minimum necessary minimum distance for operating the vehicle by authenticating the badge ID with the external antenna AX.

  The internal antenna AI determines the second communication area ZO with the badge ID and permits starting. This region is defined by the magnetic field emitted from the internal antenna. Therefore, it is necessary to authenticate the badge ID by the internal antenna AI and guarantee a fixed area for starting the vehicle, and this area is the cabin VH of the vehicle V.

  In practice, the reach of the magnetic field emitted from these internal antennas AI is wider than the cabin VH, but this magnetic field is limited by the metal shell of the cabin VH of the vehicle V and leaks through the window opening. Note that.

  The detection of the badge ID in the second region ZO uses the phenomenon that the badge is initialized with a fixed threshold value S0 that varies depending on the received magnetic field B0 called the nominal magnetic field. In a non-limiting manner, this fixed threshold value S0 is the power P0 corresponding to the nominal magnetic field B0.

  The magnetic field Br received by the badge ID varies depending on the magnetic field Be emitted by the antenna A. The latter magnetic field Be is an area ZO that is also called a communication area, and the area ZO that represents the magnetic field Be of the antenna is Defined around the antenna.

  FIG. 2 shows how the position of the badge ID with respect to the antenna A of the antenna device changes according to the magnetic field Be of this antenna A and thus the corresponding received magnetic field Br.

  It can be seen that as the distance of the badge ID from the antenna A that emits the emission magnetic field Be increases, the corresponding reception magnetic field Br becomes weaker. When the badge ID is located at the same place as the antenna A, the received magnetic field Br is theoretically equal to the emitted magnetic field Be.

  Thus, the nominal magnetic field B0 corresponds to a nominal communication area ZO in which the badge ID can communicate with the antenna A and the transceiver device DER.

  If the badge ID is located outside this region ZO (when the received magnetic field Br is smaller than the nominal received magnetic field B0), the badge ID does not respond to a signal transmitted from the antenna device A or is intentional The radio frequency response RF that is wrong is transmitted. This means that the badge ID is located outside the vehicle cabin VH. In other situations, the badge ID responds by sending a radio frequency signal RF. As shown in FIG. 2, the nominal magnetic field B0 is determined so as to avoid the influence of the spurious magnetic field Bb generated by the radio disturbance factor, and it is noted that the value of the nominal magnetic field B0 is larger than the value of the spurious magnetic field. I want.

  FIG. 3 shows an example of positioning of the badge ID with respect to the internal antenna AI1.

  The internal antenna AI1 emits a magnetic field Be with a power of 15 watts. The fixed threshold value S0 is fixed at P0 = 5 watts. The badge ID receives the magnetic field Br1 when the badge is located at the position ID1, and the power P1 of this magnetic field Br1 is 4.5 watts and is therefore smaller than the fixed threshold value S0. Therefore, since the badge ID is located outside the area ZO defined by the threshold value S0, it does not communicate with the antenna AI1 and the transceiver device DER.

  When the badge ID is located at the position ID2, it receives the magnetic field Br2, and the electric power P2 of this magnetic field Br2 is 5.5 watts, and thus is larger than the fixed threshold value S0. Therefore, the badge ID is located in the communication area ZO and communicates with the antenna AI1 and the transceiver device DER.

  Therefore, in the method of detecting the badge ID and confirming whether this badge is located in the communication area ZO of the antenna, particularly the internal antenna AI, the following steps are performed as shown in FIG. .

  In an initial step 0), when the badge ID is manufactured, the fixed threshold value S0 is written into the badge ID memory, for example into an EEPROM type rewritable memory.

Next, when the badge ID and the antenna device A are used, that is, in the operation mode,
In the first step 1), a calibration signal S_CAL, also called a calibration frame, is sent in the direction of the antenna device A with a predetermined initial power PI, and the set power PR of the antenna device A is determined. Such a signal transmission method is shown in FIG.

  In a non-limiting embodiment, the calibration signal S_CAL is triggered by a specific event.

  In a non-limiting example, the specific event is a vehicle operation. The operation of the vehicle indicates a change in the environment of the antenna device A, that is, a temperature change (for various reasons, for example). Since the temperature change affects the components of the antenna device, the impedance Z of the antenna device, and thus the antenna device The emission magnetic field Be due to changes.

  In another non-limiting example, the specific event is a change in power supply voltage, in this case battery voltage Ubat (battery voltage can change, for example after engine start or after engine stop). Thereby, these fluctuations affecting the current flowing through the antenna device can be taken into account during calibration. In this way, battery voltage fluctuations are compensated for because the current Irm is measured after battery voltage fluctuations.

  Therefore, the purpose of this step is to take into account changes in the impedance Z of the antenna device A when determining the magnetic field Be emitted by the antenna device A, and therefore when determining the set power PR supplied to the antenna device A. There is to put.

  In the case of using the antenna device in a vehicle, the change in the impedance Z that appears when the antenna device is operating is thus taken into account in this way.

  Note that the calibration signal S_CAL is not recognized by the identification object ID. Therefore, the identification object ID receives the signal, but the identification object ID does not respond to the calibration signal S_CAL. Thus, the badge does not need to add an activation-deactivation period to receive this signal. Therefore, the badge ID receives data included in the function signal S_FONC that this badge will receive next more quickly.

Therefore, in the first sub-step 1a), the initial power PI is determined and the calibration signal S_CAL is transmitted. The initial power PI is obtained using a calibration voltage UC having an initial duty cycle α1 corresponding to the theoretical initial current Ith. This theoretical initial current Ith is experimentally determined by a vehicle test. The value of the theoretical initial current Ith varies depending on the type of the vehicle V.

  In a non-limiting embodiment, this voltage is a square wave. Therefore, waste of energy in the power stage used to apply this voltage and described below can be avoided. Energy consumption due to heat generation occurs only during the transition period, unlike a sinusoidal voltage where the power consumption is significantly increased. Therefore, the power stage is not heated to a very high temperature.

In the second sub-step 1b), when the calibration signal S_CAL is transmitted, the actual current Irm flowing through the antenna device A is measured. Actually, the initial power PI corresponding to the theoretical initial current Ith is applied, but since the antenna device A has the impedance Zr, the current flowing through the device is not actually equal to the theoretical initial current Ith.

  Measurement of the current Irm flowing through the antenna device A can be easily performed by a peak amplitude detector C described below. This current Irm is an alternating current, and the frequency spectrum of this current includes a harmonic h. In FIG. 6, the 1st to 5th harmonics are shown as simplified non-limiting examples.

  In a non-limiting embodiment, the antenna device A is tuned to the transmission frequency (frequency is for example 125 kHz). This makes it possible to emit a stronger magnetic field at the transmission frequency and to arrange a bandpass filter FL. Therefore, the bandpass filter FL can be used to reduce the amplitude of the harmonic h (excluding the first harmonic).

  In fact, at the time of transmission, on the antenna device A side, the value of the current Irm flowing through the antenna device A is equal to the sum of the harmonics h in the band of the filter included in the antenna device A. Depending on the selectivity of the filter, if the filter is a broadband pass filter as represented by FL1 in FIG. 6, all of these harmonics will be included. Further, when the filter is a narrow bandpass filter as represented by FL2 in FIG. 6, only some of these harmonics are included. Therefore, at the time of transmission, the value of the emission magnetic field Be depends on this current Irm including the harmonic h.

  At the time of reception, on the badge ID side, the value of the current Irm to be taken into account is again related only to the first harmonic h1 called the fundamental wave. The reception magnetic field Br (and consequently, the fixed threshold value S0) corresponds only to the emission magnetic field Be indicating the value of the fundamental wave, and does not correspond to the emission magnetic field indicating the total value of these harmonics.

  Therefore, it is necessary to accurately determine the power transmitted on the first harmonic h1 to enable the emission of the emission field Be corresponding to the nominal magnetic field B0, and hence the badge ID fixed threshold S0. Therefore, it is necessary to measure the current Irm and remove as much as possible the harmonics other than the fundamental wave h1.

  This operation is performed using the calibration voltage UC of the initial duty cycle α1 used for obtaining the initial power PI.

  If the calibration voltage UC is any square wave signal, all of the harmonics of the measured current Irm can be included as shown in FIG.

  In the first non-limiting embodiment, the calibration voltage UC is a symmetric voltage. As can be seen from FIG. 7, in this case, even-order harmonics of the measurement current Irm are removed. As can be seen, the voltage UC is symmetric with respect to the point PT. The symmetrical voltage UC enables accurate generation and accurate measurement of the initial power PI corresponding to the first harmonic h1 by removing spurious currents due to other harmonics.

In frequency display, n-th harmonic is expressed in terms _{a n cos (nωt) + b} n sin (nωt).

Voltage UC is an odd function, when another way, f (-x) = - holds f (x) is, therefore, Fourier series expansion of the function includes only sine terms, the coefficient a _n zero is there.

Therefore, if it is found that Cn = (1 / T) ∫f (x) e ^−jnωx dx and Cn = (1/2) (an−jbn), the following expression is obtained.
Cn = j (2E / πn). sin (nπα1). sin (n (π / 2))
And bn = (4E / πn). sin (nπα1). sin (n (π / 2))
In the above equation, ω = 2π / T, and T and E are the period and amplitude of the power supply voltage Ubat of the antenna device.

Therefore, the Fourier series corresponding to the symmetrical voltage signal UC is equal to:
f (x) = Σ (4E / πn). sin (nπα1). sin (n (π / 2)). sin (nωx),
In the above equation, n = 1,. . . , ∞, or the Fourier series is equal to:
f (x) = Σ (4E / π (2p + 1)). sin ((2p + 1) πα1). sin ((2p + 1) (π / 2)). sin ((2p + 1) ωx),
In the above equation, p = 0,. . . , ∞,
This equation gives the harmonic spectrum shown in FIG.
The value of the fundamental wave h1 is given by:
h1 = (4E / π). sin (πα1). sin (ωx)

  Furthermore, it should be noted that waste of energy in the power stage P transistors can be avoided by realizing a square wave voltage. In fact, energy consumption due to heat generation occurs only during the transition period, unlike a sinusoidal voltage where power consumption is significantly increased. Therefore, the power stage P is not heated to an extremely high temperature.

  Note that the value of the initial power PI can be adjusted using the value of the adjustable duty cycle α1.

  Thus, with the symmetric square wave voltage, on the one hand, the transmission initial power PI can be set to the required value corresponding to the required communication area ZO (thus the transmission power PI can be generated accurately), On the other hand, an accurate measurement of the actual transmission power PI corresponding to the actual received power of the badge ID is obtained because the even harmonics are removed.

  In a second non-limiting embodiment, the calibration voltage UC includes a voltage with a 1/3 duty cycle, which corresponds to a π / 3 offset of the voltage signal UC. As can be seen from FIG. 8, in this case, harmonics of the order of multiples of 3 of the measured current Irm are removed.

  Note that the two embodiments can be combined. In this case, as can be seen from FIG. 9, the first and fifth harmonics remain as a result, and the latter fifth harmonic can be ignored.

  In this way, the current Irm flowing through the antenna device A can be accurately measured. Therefore, the measurement current Irm represents in this case the amplitude of the fundamental wave of the emitted magnetic field.

  As a result, when it is known that the emission magnetic field Be is proportional to the measured current Irm, based on the amplitude, the initial power PI (and thus the emission) that is transmitted by the antenna device A and exactly corresponds to the received power Pr. The magnetic field Be) can be estimated.

Recall that the magnetic field B contains three components in the orthogonal space x, y, z, as shown in FIG. 10, as known to those skilled in the art. These components are given by:
B _μ = (Ae Im / 2πd ³ ) ^* cos θ,
B _θ = (Ae Im / 4πd ³ ) ^* sin θ, and B _φ = 0,
In the above equation, Ae is the actual surface area of the antenna through which the magnetic field B passes, and d is the distance that allows the measurement of the magnetic field B and is measured from the center of the antenna.

Ae = N _W ^* A ^* μ _rod may hold when N _W is the number of antenna windings, A is the cross-sectional area of the ferrite core of the winding, and μ _rod is the apparent permeability of the ferrite core. I want to recall.

  It should also be noted that the calibration voltage UC is obtained by a power stage P including an H-bridge that performs full-bridge control described below.

In the third sub-step 1c), the measured current Irm is compared with the theoretical initial current Ith. The actual impedance Zr of the antenna device A is derived using the difference, and accordingly, the set power PR applied to the antenna device A is derived.

  Recall that in order to determine the region ZO located around the antenna device A and corresponding to the passenger compartment VH of the vehicle, the emission magnetic field Be corresponding to the power PR is derived. Thus, this desired magnetic field with a known value corresponds to a known current Iv. In order to supply this known desired current Iv to the antenna device A, the power PR of the antenna device needs to be set in consideration of the impedance Zr of the antenna device.

  The set power PR is set using a function voltage UF having a set duty cycle α2.

Therefore, in the fourth sub-step 1d), the set duty cycle α2 is determined.

The calculated value of the set duty cycle α2 is estimated as follows.
The following equation holds: Irm = (Ubat ^* sin (α1π)) / Zr, thus the following equation is obtained:
Zr = (Ubat ^* sin (α1π)) / Irm, and Iv = (Ubat ^* sin (α2π)) / Zr, so that:
sin (α2π) = (Zr ^* Iv) / Ubat = (Ubat ^* sin (α1π) ^* Iv)) / (Irm ^* Ubat) = sin (α1π) ^* (Iv / Irm))
Therefore, the following equation is obtained.
α2 = (1 / π) ^* Arcsin (sin (α1π) ^* (Iv / Irm)) [1]

  Note that the actual impedance Zr of the antenna device A is no longer included in the calculation formula [1] of the set duty cycle α2 in practice.

  In the first non-limiting embodiment, the set duty cycle α2 is calculated by the microprocessor of the transceiver device DER described below.

  In the second embodiment, which is simpler and faster, the set duty cycle α2 is expressed by the formula sin (α1π) / sin (α2π) = Irm / based on a pre-filled mapping table (not shown). Defined by using Iv [2]. In this table, whenever a difference between the measured current Irm flowing through the antenna device when the calibration signal S_CAL is transmitted and the theoretical current Ith occurs, the difference corresponds to the desired function current Iv and the impedance Zr of the antenna device A The set duty cycle α2 taking into account the change is taken from the table.

上のテーブルでは、Ｉｖ１，Ｉｖ２，Ｉｖ３などは、所望電流Ｉｖの種々の値であり、Ｉｒｍ１，Ｉｒｍ２，Ｉｒｍ３などは、アンテナ装置Ａを流れる測定電流Ｉｒｍの種々の値であり、α２₁₁．．．α２₂₁．．．α２₃₁．．．などは、対応する種々の設定デューティサイクル値である。 Such a table has the following form:

In the table above, Iv1, Iv2, Iv3, etc. are various values of the desired current Iv, Irm1, Irm2, Irm3, etc. are various values of the measured current Irm flowing through the antenna device A, and α2 ₁₁ . . . α2 ₂₁ . . . α2 ₃₁ . . . Are various corresponding set duty cycle values.

  Applying equation [1] or selecting the set duty cycle α2 from this mapping table uses a curve CZ representing the actual impedance Zr, as shown in FIG. 11 for a non-limiting example. Therefore, the set duty cycle α2 to be applied to the antenna device A is obtained.

  The duty cycle α is on the x-axis and the current I is on the y-axis. As can be seen from the figure, a voltage having an initial duty cycle α1 is applied corresponding to the theoretical initial current Ith. The correlation point between the initial duty cycle α1 and the theoretical initial current Ith is located on a curve CZth representing the theoretical impedance Zth of the antenna apparatus A.

  The actual current Irm flowing through the device and having an initial duty cycle α1 is measured. The correlation point between the initial duty cycle α1 and the measured actual current Irm is located on a curve representing the actual impedance Zr of the antenna device A. Two curves are shown, a maximum curve CZrmax and a minimum curve CZrmin of this actual impedance Zr. In this example, the curve CZmax is drawn so as to correspond to the maximum value Zrmax of the actual impedance.

  Finally, for the desired current Iv, the corresponding set duty cycle α2 is determined by drawing a curve representing the actual impedance Zr, in this case CZmax, and projecting it on the x-axis.

  Accordingly, the set duty cycle α2 is determined so that the desired power PR can be obtained in the antenna device A by applying the desired function voltage UF.

  It should be noted that the function voltage UF is obtained by a power stage P including an H-bridge that performs full-bridge control and half-bridge control described below.

  Accordingly, this first calibration step 1) corresponds to automatic calibration of the detection system SYS for determining the set power PR. In fact, external measuring means are not necessary for this calibration. Furthermore, this automatic calibration is dynamic in that the automatic calibration begins while the antenna device is in operation and when the antenna device begins, for example, other than when it is being debugged in the factory.

  In the second step 2), after transmitting the calibration signal S_CAL, the function signal S_FONC, which is also called a function frame, is then set in the direction of the antenna device A as shown in FIG. The antenna device A emits a predetermined magnetic field corresponding to the vehicle cabin VH in the example of the vehicle application corresponding to the desired area ZO.

  In a third step 3), the magnetic field Br corresponding to the magnetic field Be received by the identification object ID and emitted from the antenna device A is measured. This measurement is performed using a measurement device known to those skilled in the art and having an RSSI (received signal intensity display) function with a built-in amplifier included in the identification object ID.

  In the fourth step 4), the received magnetic field Br is compared with the nominal magnetic field B0. This comparison is performed within the identification object ID.

  In a fifth step 5), a determination as to whether the badge ID is located in the area ZO around the antenna device A is made based on this comparison.

  Therefore, when the received magnetic field Br is larger than the nominal magnetic field B0, the badge ID is located in the area ZO around the antenna device A, and thus inside the vehicle cabin VH. Next, as shown in FIG. 5, the badge ID returns an acknowledgment REPOK to the control device DC of the transceiver device DER. Next, for example, the vehicle can be started by the latter control device.

  On the other hand, if the received magnetic field Br is smaller than the nominal magnetic field B0, the badge ID is located outside the area ZO and thus outside the vehicle cabin VH. In this case, the badge ID does not return a response, and the badge ID behaves as if it did not receive the function signal S_FONC from the antenna device A, or returns a negative response REPNOK to the control device DC as shown in FIG. The latter control device DC then prevents any vehicle starting, for example.

  In another variant, the badge ID systematically sends a response REP containing the result of the comparison, regardless of whether the badge ID is located inside or outside the area ZO.

The method described so far is performed by the detection system SYS shown in the non-limiting embodiment of FIG. The detection system SYS
A transceiver device DER, the transceiver device DER comprising:
A control device DC;
A power stage P;
A current measuring device C;
A signal receiver RE for receiving a response REPOK, REPNOK from the identification badge ID based on a comparison made between the received magnetic field Br and the nominal magnetic field B0, the detection system SYS further comprising:
-Antenna device A;
-Receiver-Transmitter, in this case an identification badge ID.

  Note that according to a non-limiting embodiment, all of the components of the transceiver device DER are housed in one and the same electronic card. Thereby, communication between various components can be performed at higher speed and with higher reliability. In contrast, if these components are placed separately, the communication links connecting these components can be more easily disrupted and the bit rate of these links is reduced. There is a fear.

  The identification badge ID is known to those skilled in the art and will not be described here.

  Other components will be described in further detail below.

・ Antenna device A
In the first non-limiting embodiment, the antenna device A is configured by an RL circuit. The latter RL circuit needs to amplify the power supply voltage of the antenna device to enable the appropriate magnetic field emission.
In the second non-limiting embodiment, the antenna device A is constituted by an RLC circuit. The latter RLC circuit can directly amplify the current I flowing through the antenna device A using the power supply voltage of the antenna device A, in this case the battery voltage Ubat of the vehicle V, so that the appropriate magnetic field emission is Unlike the case of the first embodiment, this is possible without using voltage locking. Thus, this configuration is a solution that is easier to put into practice to achieve amplification. As can be seen from the above description, this RLC circuit also functions as a band pass filter.

・ Control device CD
A signal transmitter EM, the signal transmitter EM
-Send calibration signal S_CAL in the direction of antenna device A;
-Send the function signal S_FONC in the direction of the antenna device A;
A control signal is sent in the direction of the power stage P to supply the power supply voltage Ubat to the antenna device A, the control device CD further comprising:
A comparator CMP of currents Irm and Ith;
In particular, it comprises a calculation member CALC (eg a microprocessor or ASIC) used to adapt the duty cycle α1 and α2 of the calibration voltage UC and the function voltage UF.
In a non-limiting embodiment, the control device CD further comprises
A signal receiver RE may be provided that receives the responses REPOK, REPNOK from the identification badge ID based on a comparison made between the received magnetic field Br and the nominal magnetic field B0.

・ Power stage P
This power stage P supplies a calibration voltage UC used to set the initial power PI and a function voltage UF used to set the set power PR of the antenna device A.
In a non-limiting embodiment, the power stage P is an H bridge that provides full bridge control or half bridge control. This is shown in FIG. Specifically, the power stage P includes four switches S1 to S4. These switches are MOSFET type transistors in a non-limiting example.

In order to supply the voltage, the power stage P operates in the full bridge mode as follows. This example is given as an example relating to a symmetrical voltage as shown in FIG.
-During the interval t0-t1 and during the interval t2-t3, all the switches are open, or the switches S2 and S4 are closed, or the switches S1 and S3 are closed and the other switches are Either open or not. The voltage UC is zero.
-During the section t1-t2, the switches S1-S4 are closed and the other switches are open. The voltage UC is positive.
-During the section t3-t4, the switches S2-S3 are closed and the other switches are open. The voltage UC is negative.

  Since the bridge components in the two diagonal positions are controlled by two control signals that are delayed by a half period with respect to each other, symmetry can be achieved.

  When the power stage P operates in the full bridge mode, the resulting voltage can be used to achieve the first current range G1 = [I11−I12].

As shown in the example of FIG. 14, the power stage P operates in the half-bridge mode as follows. Note that switch S4 is always closed.
-During the interval t0-t1 and during the interval t2-t3, the three other switches S1-S2-S3 are open or the switch S2 is closed and the other two switches S1-S3 are open Either. The voltage UC / UF is zero.
-During the section t1-t2, the switch S1 is closed and the other two switches S2-S3 are open. The voltage UC / UF is positive. Alternatively, the switch S2 is closed and the other two switches S1-S3 are open. The voltage UC / UF is negative.
When power stage P operates in half-bridge mode, the resulting voltage is used to achieve a second current range G2 = [I21-I22] that is narrower than the first range, specifically twice as narrow can do.

  Therefore, by using the power stage P, not only the initial power PI is obtained using the calibration voltage UC, but also the set power PR is obtained using the function voltage UF.

  Thus, depending on the desired current Iv that needs to be realized, the power stage P is used in full-bridge mode (wide current range G1) or in half-bridge mode (narrow current range G2).

  This makes it possible to realize the magnetic field Be via the antenna device A that is adjusted according to the desired vehicle type. For example, in the case of a family type vehicle, a full bridge is used to supply the emission magnetic field Be corresponding to the region ZO that defines the cabin VH of this family vehicle, whereas in the case of a coupe type vehicle having a narrow cabin, a half bridge is used. Used to supply the emitted magnetic field Be corresponding to this different narrow cabin.

  Thus, with this full-bridge mode operation or half-bridge mode operation, the appropriate magnetic field reaching region that varies depending on the type of vehicle does not change the RLC circuit of the antenna device A, and thus adapts the resistance R of this circuit. Obtained without need. The control device DC is strictly programmed according to the type of the vehicle V to operate the power stage P appropriately.

  Furthermore, it may be necessary to widen the current range for one and the same vehicle, for example when a large variation occurs in the vehicle battery voltage Ubat. The set power PR necessary for transmitting the function signal S_FONC varies depending on the battery voltage and the impedance Zr of the antenna device. In order to compensate for variations in the battery voltage Ubat, the set duty cycle α2 is appropriately set. For example, when the battery voltage is high, the power stage P is operated in the half bridge mode, whereas when the battery voltage is low, the power stage P is operated in the full bridge mode.

  In order to provide a continuous range between the two current ranges G1 and G2, in a non-limiting embodiment, the set duty cycle α2 is contained within the interval [1 / 6−1 / 2]. This state is shown in FIG. 15 showing the relationship of duty cycle-current. Take the duty cycle α on the x-axis and the current I on the y-axis. On the y-axis, the respective limit values I11, I12 and I21, I22 of the two ranges G1 and G2 can be found. When the duty cycle α2 changes within the interval [1 / 6−1 / 2], it can be seen that the curve CG2 of the second current range G2 applies when operating in the half-bridge mode 1 / 2H. In contrast, when operating in the full bridge mode H, the curve CG1 of the first range G1 applies. Finally, it can be seen that when changing from half-bridge mode operation to full-bridge mode operation, the change from the range G2 to G1 is continuous, that is, no jump occurs in the current value I.

  In another embodiment, when the duty cycle α2 changes within the interval [1 / 6−αmax ′] where αmax ′ is less than 1/2, as shown in FIG. It can be seen that a jump occurs when changing from the half-bridge mode to the full-bridge mode. Therefore, in this case, a predetermined current value cannot be taken into consideration when determining the power of the antenna device A. These current values fall within the hatched sections I22 'to I22. In the latter full-bridge mode, the lower limit value αmin of the section needs to be less than 1/6 in order to ensure continuity.

・ Current measurement device C
In the first embodiment, the current measuring device is a peak amplitude detector. This peak amplitude detector is a simple means of measuring current. This measure can be used to measure the maximum amplitude of current that is ultimately required since unwanted harmonics have been removed by a symmetric command and 1/3 duty cycle. Therefore, the fundamental wave value of this current is obtained by this measurement. As is conventional, the current measuring device includes a diode and a capacitor as shown in FIG.

  As shown in FIG. 12, the current measuring device transmits a measured current value Im to the calculation member CALC.

Of course, other current measuring means can be used.
For example, the current measuring device C can be a digital sampling device or a device that rectifies the current and then averages the rectified current.

  Note that antenna device A comprises one or more antennas. In the non-limiting example described, the antenna device A includes a plurality of antennas as can be seen from the above description. In this case, for each antenna of the antenna device A, the current flowing through the antenna is set to realize the nominal magnetic field B0 associated with the communication area ZO between the badge ID and the antenna. Therefore, the badge ID has a plurality of fixed threshold values S0 associated with each antenna of the antenna device A.

  It should be noted that the example given above has been described in connection with an internal antenna. Of course, the present method can be applied to an external antenna as required.

  In addition, these examples relate to the antenna device A that transmits a low frequency signal and the identification badge ID that transmits a radio frequency signal, but other examples relating to signal transmission at other frequencies can be given. Please keep in mind.

  In addition, for example, in a situation where another door is released, even when the door is not switched to the locked state despite the locking operation, by performing switching control so that the door is in the locked state, It is also possible to prevent forgetting to lock. Specifically, a control device (DC) provided in the vehicle, an internal antenna device (AI) provided in the vehicle, an external antenna device (AX) provided outside the vehicle, and an identification object (ID), In a system (SYS) for detecting an identification object (ID) located in a region (ZO) around an antenna device (A) provided on a vehicle body, a control device (DC) sends a calibration signal (S_CAL) internally and externally. Send to antenna device (AI) (AX) to determine set power (PR), send function signal (S_FONC) corresponding to set power (PR) to internal and external antenna device (AI) (AX) The internal and external antenna devices (AI) (AX) emit a predetermined magnetic field (Be), and are performed between the magnetic field (Br) received by the identification object (ID) and the nominal magnetic field (B0). For comparison Based on this, it can be determined whether or not the identification object (ID) is located inside the area (ZO) (first communication area) around the internal and external antenna devices (AI) (AX), The object (ID) can measure the received magnetic field (Br) corresponding to the emitted magnetic field (Be) and compare the received magnetic field (Br) with the nominal magnetic field (B0), ID) is determined to be located in the area (first communication area), the door does not switch to the locked state even though the locking / unlocking detector provided outside the door is locked. When it is determined that the identification object (ID) is no longer located in the area (ZO) and (first communication area) (or a predetermined time has elapsed), the unlocked door is in the locked state. It is equipped with a locking control device that performs switching control System (SYS) is proposed, wherein Rukoto.

  By using this system, when the locking operation is performed in a state where the identification object is determined to be located in the communication area, for example, the door is opened only when the driver is out of the communication area. It can be in a locked state, and forgetting to lock can be prevented. However, when the driver gets into the vehicle again for some reason, the locked state is not established, and in that case, the timer for counting the predetermined time may be canceled.

Accordingly, the present invention has the following advantages.
A method for controlling the value of the magnetic field emitted by the antenna device A by adjusting the power at the time of transmission, which makes it possible to set a fixed threshold value of the identification object and is easier to manage than the variable threshold value of the object; provide.
By writing a predetermined fixed threshold value in the identification object ID, it is possible to avoid radio disturbances and thus avoid spurious magnetic fields.
-Furthermore, this threshold value is fixed for all of the vehicle group, so that it is possible to have a common identification object ID that operates on all vehicles, and the communication area ZO only depends on the transmission power Pe and thus the antenna device Adapt only by the current I flowing through A.
The power is regulated by duty cycle adjustment, which is less expensive than voltage regulation performed with a fixed duty cycle.
-Unlike the solution for adjusting the power supply voltage Ubat, the duty cycle is adjusted based on the current, and the adjustment based on the current is more effective than the setting based on the battery voltage because the change of the impedance Zr of the antenna device A is corrected. Is accurate and accurate.
-Even-order harmonics can be prevented from being transmitted by symmetric H-bridge control, and therefore, compatibility with electromagnetic waves and EMC (ELECTROMAGNETIC COMPATIBILITY) problems can be reduced.
-By performing symmetric calibration control using a 1/3 duty cycle, it is possible to measure current accurately with simple measuring means such as a peak amplitude detector.
-By performing the control using a square wave voltage, it is possible to avoid overheating of the transistors in the power stage.
-The present invention provides a method for obtaining a wide current range, if necessary, for one same vehicle or for different vehicles without having to adapt the circuit of the antenna device A.
The calibration step used to determine the set power and to determine the value of the magnetic field emitted by the antenna device is dynamic because the step is performed while the antenna device is operating.
-The dynamic calibration step is different from the static calibration step which is performed upstream, i.e. while the antenna device is installed in the vehicle (i.e. when debugging the antenna device). There is no need to add it (thus even before the production of the vehicle begins and before the vehicle is sold).
-According to the invention, the value of the magnetic field emitted from the antenna device when the antenna device is used in a vehicle, taking into account the change in impedance of the antenna device that appears while the antenna device is used, It becomes possible to control by setting a fixed threshold value of the identification object.
-Using the detection system including the antenna device and the identification object, automatic calibration of the antenna device can be performed without using external measuring means.

  Obviously, the present invention is not limited to the applications described with respect to automobiles, but can be applied to all cases involving low frequency antennas and identification objects, for example home automation.

V Vehicle DER Transceiver device A Antenna device AX, AX1, AX2, AX3, AX4, AX5 External antenna AI, AI1, AI2 Internal antenna ID Receiver-transmitter, identification object, badge VH Room VC Rear bumper Be, BeI, BeX , Br1, Br2, B Magnetic field BF Low frequency signal RF Radio frequency signal, radio frequency response B0 Received magnetic field, nominal magnetic field, nominal received magnetic field S0 Fixed threshold P0 Power ZO Communication area Br Received magnetic field
ID1 Position ID2 Position S_CAL Calibration signal PI Initial power PR Set power Z, Zr Impedance Ubat Battery voltage, power supply voltage Im Measurement current Irm Current Ith Theoretical initial current UC Calibration voltage C Peak amplitude detector h Harmonic h1 First harmonic FL Band pass filter FL1 broadband pass filter PT point a _n coefficient T supply voltage cycle E supply voltage amplitude x of, y, it is possible to measure the actual surface area d the magnetic field B of the antenna through which z orthogonal space Ae field B, the antenna Distance Iv from Center Iv Known Current α1 Initial Duty Cycle α2 Set Duty Cycle Ith Theoretical Initial Current Zth Theoretical Impedance CZth Theoretical Impedance Curve CZmax Maximum Curve CZmin Minimum Curve SYS Detection System S_FONC Function Signal DC Controller RE Signal receiver REP Response REPOK Positive response REPNOK Negative response UC Calibration voltage UF Function voltage CALC Calculator S1, S2, S3, S4 Switch G1 First current range G2 Second current range H Full bridge mode 1 / 2H Half bridge mode

Claims (1)

A system (SYS) for detecting an identification object (ID) located in a region (ZO) around an antenna device (A) provided on a vehicle body, the system being a control device (DC) provided in the vehicle And an internal antenna device (AI) provided inside the vehicle, an external antenna device (AX) provided outside the vehicle, and an identification object (ID),
The control device (DC)
Send the calibration signal (S_CAL) to the internal and external antenna devices (AI) (AX) to determine the set power (PR),
A function signal (S_FONC) corresponding to the set power (PR) is sent to the internal and external antenna devices (AI) (AX), and the internal and external antenna devices (AI) (AX) emit a predetermined magnetic field (Be). Like
Based on the comparison performed between the magnetic field (Br) received by the identification object (ID) and the nominal magnetic field (B0), the identification object (ID) is connected to the internal and external antenna devices (AI) (AX). It can be determined whether it is located inside the surrounding area (ZO) (first communication area),
The identification object (ID) can measure the received magnetic field (Br) corresponding to the emitted magnetic field (Be) and compare the received magnetic field (Br) with the nominal magnetic field (B0),
Furthermore, when it is determined that the identification object (ID) is located in the area (first communication area), the door is operated despite the locking operation of the locking / unlocking detector provided outside the door. When it is determined that the identification object (ID) is no longer located in the area (ZO) and the (first communication area) (or a predetermined time has passed) when is not switched to the locked state. A system (SYS) comprising a locking control device that performs switching control so that the door of the door is locked.

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