Rapid positioning method of intelligent key

Abstract

The invention provides a rapid positioning method for an intelligent key, and belongs to the technical field of automobile intelligent keys, and the method comprises the steps: S1, employing an internal measurement mode of an intelligent key end to measure the magnetic field intensity, and obtaining a group of internal reference values of the magnetic field intensity for environment error compensation; s2, using an intelligent key to measure the magnetic field intensity of the vehicle interior boundary and the magnetic field intensity of the vehicle exterior boundary, and setting the magnetic field intensity of the vehicle interior boundary and the magnetic field intensity of the vehicle exterior boundary as a vehicle interior effective detection area boundary threshold value and a vehicle exterior effective detection area boundary threshold value respectively; and S3, performing error compensation on the magnetic field intensity measured by the intelligent key to obtain a measured value A and a measured value B, and comparing and judging the measured value A, the measured value B, the boundary threshold of the effective detection area inside the vehicle and the boundary threshold of the effective detection area outside the vehicle to obtain a positioning result. According to the invention, the occupied MCU resource is less, the actual demand can be met, and the development task can be quickly completed in the switching of the new vehicle type.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile intelligent key, and particularly relates to a rapid positioning method of intelligent key. BACKGROUND

[0002] With the rapid development of automobile industry, the keyless entry system has been mature and popular. The keyless entry system is a kind of automobile entry and starting system realized by using radio frequency identification technology (RFID). The keyless entry system is provided with an intelligent key. When the intelligent key is in an effective range, the owner only needs to pull the door or press the one-key starting switch, and the system will automatically unlock the door or start the engine without manually using the key.

[0003] There are various schemes for identifying the position of the intelligent key inside and outside the vehicle. At present, the most common positioning methods are: adjusting the sensitivity of the low-frequency receiving antenna at the intelligent key end positioning method, RSSI-based ranging positioning method, etc.

[0004] The adjusting sensitivity of the low-frequency receiving antenna at the intelligent key end positioning method adjusts the inductance and capacitance parameters of the resonant circuit at the intelligent key end through hardware design, sets the area that can wake up the intelligent key receiving coil as the effective sensing area, and can roughly judge the position of the intelligent key through the effective sensing area. This method is simple, but the precision is poor and easy to misjudge.

[0005] The RSSI-based ranging scheme reflects the mapping relationship between the RSSI value and the distance according to the attenuation model of the radio frequency signal in the vehicle interior and exterior environment, and improves the ranging accuracy through various constraint conditions and compensation algorithms, and then obtains the accurate position of the intelligent key through the multilateral positioning algorithm. In order to accurately obtain the accurate position of the intelligent key, an electromagnetic simulation model of the vehicle needs to be established, and then the attenuation model equation of the radio frequency signal is obtained through simulation and calculation according to the loss of the wireless signal inside and outside the vehicle. Then, the accurate position of the intelligent key is obtained through the multilateral positioning algorithm. This method requires high ranging accuracy, and various algorithms are complex. When the vehicle type is changed or the software program is transplanted and maintained, simulation or calculation needs to be performed again, which occupies more MCU resources. SUMMARY

[0006] In order to solve the problems of the prior art, the present application provides an improved rapid positioning scheme of the intelligent key. The magnetic field strength (RSSI value) is measured, the magnetic field strength threshold is set, and the specific position of the intelligent key is quickly judged according to the strength of the low-frequency signal.

[0007] In a first aspect, an embodiment of the present application provides a rapid positioning method of an intelligent key, comprising:

[0008] Step S1, optimizing the measurement accuracy of the magnetic field strength: using the internal measurement mode of the smart key to measure the magnetic field strength, obtaining a set of internal reference values of the magnetic field strength for environmental error compensation;

[0009] Step S2, setting the magnetic field strength threshold: using the smart key to measure the magnetic field strength at the in-vehicle boundary and the magnetic field strength at the out-of-vehicle boundary, and setting the magnetic field strength at the in-vehicle boundary and the magnetic field strength at the out-of-vehicle boundary as the in-vehicle effective detection area boundary threshold and the out-of-vehicle effective detection area boundary threshold, respectively.

[0010] Step S3, positioning judgment based on the magnetic field strength: using the in-vehicle low-frequency antenna and the out-of-vehicle low-frequency antenna of the vehicle-mounted base station to respectively send low-frequency signals, and obtaining measurement value A and measurement value B after error compensation of the magnetic field strength measured by the smart key, and comparing measurement value A, measurement value B, the in-vehicle effective detection area boundary threshold and the out-of-vehicle effective detection area boundary threshold to obtain the positioning result.

[0011] Preferably, step S1 includes: placing the smart key and the low-frequency antenna of the vehicle-mounted base station in an electromagnetic shielding box; setting the smart key to the internal measurement mode; driving the low-frequency antenna of the vehicle-mounted base station to emit low-frequency signals by the vehicle-mounted base station at a fixed drive current multiple times; the smart key receives and measures the magnetic field strength multiple times; obtaining the average value of the multiple measured magnetic field strengths to obtain a set of internal reference values of the magnetic field strength for environmental error compensation, and storing in the EEPROM of the smart key.

[0012] Preferably, step S2 includes: setting the position close to the inner side of the vehicle door as the in-vehicle boundary, and setting the out-of-vehicle preset distance as the out-of-vehicle boundary; measuring the magnetic field strength at the in-vehicle boundary by the smart key and setting it as the in-vehicle effective detection area boundary threshold; measuring the magnetic field strength at the out-of-vehicle boundary by the smart key and setting it as the out-of-vehicle effective detection area boundary threshold.

[0013] Preferably, in step S2, the in-vehicle effective detection area boundary threshold and the out-of-vehicle effective detection area boundary threshold are saved to the FLASH of the MCU of the vehicle-mounted base station.

[0014] Preferably, before step S2, it further includes a low-frequency antenna calibration step: adjusting the working current of the in-vehicle low-frequency antenna by driving the in-vehicle low-frequency antenna by the vehicle-mounted base station in sequence, so that the magnetic field covers the entire in-vehicle space; adjusting the working current of the out-of-vehicle low-frequency antenna by driving the out-of-vehicle low-frequency antenna by the vehicle-mounted base station in sequence, so that the magnetic field covers the preset distance of the out-of-vehicle space.

[0015] Preferably, in step S3, the step S3 comprises: the vehicle-mounted base station drives the in-vehicle low-frequency antenna to send a low-frequency signal, the smart key, after switching between the external measurement mode and the internal measurement mode, obtains a measurement value A through error compensation calculation; the vehicle-mounted base station drives the out-of-vehicle low-frequency antenna to send a low-frequency signal, the smart key, after switching between the external measurement mode and the internal measurement mode, obtains a measurement value B through error compensation calculation; the vehicle-mounted base station compares and judges the measurement value A, the measurement value B, the in-vehicle effective detection area boundary threshold value and the out-of-vehicle effective detection area boundary threshold value to obtain a positioning result.

[0016] Preferably, in step S3, the step S3 further comprises: the smart key transmits the measurement value A and the measurement value B to the vehicle-mounted base station through high-frequency transmission.

[0017] Preferably, in step S3, the positioning result comprises: if the measurement value A is greater than the in-vehicle effective detection area boundary threshold value and the measurement value B is less than the out-of-vehicle effective detection area boundary threshold value, the smart key is in the vehicle; if the measurement value A is greater than the in-vehicle effective detection area boundary threshold value and the measurement value B is greater than the out-of-vehicle effective detection area boundary threshold value, the smart key is in the vehicle; if the measurement value A is less than the in-vehicle effective detection area boundary threshold value and the measurement value B is greater than the out-of-vehicle effective detection area boundary threshold value, the smart key is out of the vehicle; and if the measurement value A is less than the in-vehicle effective detection area boundary threshold value and the measurement value B is less than the out-of-vehicle effective detection area boundary threshold value, the smart key is not in the effective detection area.

[0018] Preferably, in step S3, the vehicle-mounted base station is provided with three in-vehicle low-frequency antennas and three out-of-vehicle low-frequency antennas, and the step S3 comprises: the vehicle-mounted base station drives the three in-vehicle low-frequency antennas to send low-frequency signals; the smart key, after switching between the external measurement mode and the internal measurement mode, obtains a measurement value of each of the three in-vehicle low-frequency antennas through error compensation calculation, and takes the maximum value of the measurement values of the three in-vehicle low-frequency antennas as the measurement value A; the vehicle-mounted base station drives the three out-of-vehicle low-frequency antennas to send low-frequency signals respectively; the smart key, after switching between the external measurement mode and the internal measurement mode, obtains a measurement value of each of the three out-of-vehicle low-frequency antennas through error compensation calculation, and takes the maximum value of the measurement values of the three out-of-vehicle low-frequency antennas as the measurement value B; and the in-vehicle effective detection area boundary threshold value is , and the out-of-vehicle effective detection area boundary threshold value is , and the positioning result is obtained by comparing , , , , , .

[0019] > and < , indicating that the smart key is in the in-vehicle effective detection area and not in the out-of-vehicle effective detection area, the smart key is in the vehicle;

[0020] and , indicating that the smart key is in the overlap area of the in-vehicle effective detection area and the out-of-vehicle effective detection area, the smart key is in the vehicle;

[0021] and , indicating that the smart key is in the out-of-vehicle effective detection area and not in the in-vehicle effective detection area, the smart key is outside the vehicle;

[0022] and , indicating that the smart key is not in the out-of-vehicle effective detection area and not in the in-vehicle effective detection area, the smart key is not in the effective detection area.

[0023] Preferably, after the smart key is switched between the external measurement mode and the internal measurement mode, the measurement value is obtained by error compensation calculation, and the measurement value step is: setting a group of internal reference values of magnetic field intensity , , ; set the smart key to the external measurement mode, complete the external measurement to obtain a group of magnetic field intensity , , ; set the smart key to the internal measurement mode, and measure again to obtain a group of magnetic field intensity , , ; the measurement value after error compensation is :

[0024] = + ( - ),

[0025] = + ( - ),

[0026] = + ( - ),

[0027] ​​​​​​ = .

[0028] The present application has the advantages that:

[0029] The present application reduces the algorithm difficulty for intelligent key positioning, occupies less MCU resources, can meet the actual needs, and can quickly complete the development task in the switching of new vehicle models. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 A flowchart of a quick positioning method of an intelligent key according to an embodiment of the present application is shown in the figure;

[0031] Figure 2 An antenna distribution and coverage area diagram according to an embodiment of the present application is shown in the figure;

[0032] Figure 3 A flowchart of an optional specific implementation method of step S1 according to an embodiment of the present application is shown in the figure;

[0033] Figure 4 A flowchart of an optional specific implementation method of step S2 according to an embodiment of the present application is shown in the figure;

[0034] Figure 5 A flowchart of an optional specific implementation method of step S3 according to an embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0035] In order for those skilled in the art to better understand the technical solutions of the present application, the following describes exemplary embodiments of the present application in conjunction with the accompanying drawings, including various details of the embodiments to help understanding, which should be considered only as exemplary. Therefore, those skilled in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present application. Also, for the sake of clarity and conciseness, the description below omits the description of well-known functions and structures.

[0036] In the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0037] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0038] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. "Coupled" or "connected" or similar terms are not restricted to physical or mechanical connections or associations, but can also include electrical connections, whether direct or indirect.

[0039] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an overly literal or overly formal sense unless expressly so defined herein.

[0040] In the technical solutions of the present application, the collection, storage, use, processing, transmission, provision and disclosure of user personal information comply with relevant laws and regulations and do not violate public order and good customs. The use of user data in the technical solutions complies with relevant national laws and regulations (for example, "Information Security Technology Personal Information Security Specification" and the like). For example, appropriate measures are taken for personal information access control; the display of personal information is limited by regulations; the use purpose of personal information does not exceed the direct or reasonably related range; the use of personal information eliminates explicit identity pointing and avoids precise positioning to a specific individual.

[0041] Figure 1 A flowchart of a method for quickly positioning an intelligent key according to an embodiment of the present application is shown in FIG. 1. As shown in FIG. 1, the method comprises the following steps. Figure 1

[0042] Step S1: optimizing the measurement accuracy of the magnetic field strength: using the internal measurement mode of the intelligent key to measure the magnetic field strength (RSSI value) to obtain a set of internal reference values of the magnetic field strength for environmental error compensation.

[0043] Step S2: setting the magnetic field strength threshold: using the intelligent key to measure the magnetic field strength at the boundary inside the vehicle and the magnetic field strength at the boundary outside the vehicle, and setting the magnetic field strength at the boundary inside the vehicle and the magnetic field strength at the boundary outside the vehicle as the boundary threshold of the effective detection area inside the vehicle and the boundary threshold of the effective detection area outside the vehicle, respectively.

[0044] ​Step S3, positioning judgment based on magnetic field strength: the in-vehicle low-frequency antenna and the out-of-vehicle low-frequency antenna of the vehicle-mounted base station respectively send low-frequency signals, and the measured values A and B of the magnetic field strength measured by the smart key after error compensation are obtained. The measured values A and B, the in-vehicle effective detection area boundary threshold and the out-of-vehicle effective detection area boundary threshold are compared to obtain the positioning result.

[0045] The smart key has an RSSI measurement function; the vehicle-mounted base station is provided with an out-of-vehicle low-frequency transmitting antenna and an in-vehicle low-frequency transmitting antenna.

[0046] RSSI is Received Signal Strength Indication, which is an indicator of the signal strength (magnetic field strength) received by a wireless communication device.

[0047] In some embodiments, as shown in Figure 2 The vehicle-mounted base station is equipped with three in-vehicle low-frequency transmitting antennas (1, 2, 3) and three out-of-vehicle low-frequency transmitting antennas (4, 5, 6). The front in-vehicle antenna 1 is installed vertically to the center of the vehicle body at the central armrest position, and the out-of-vehicle antenna 4 is installed at the door handle position of the driver's cabin side door. The elliptical shadow area corresponding to the low-frequency antenna is the effective detection range of the smart key for the antenna.

[0048] In some embodiments, the vehicle-mounted base station uses a low-frequency transmitting chip NJJ29C0B and a high-frequency receiving chip ATMEL5785. The smart key uses an ATA5702 chip, which has a high-precision RSSI measurement function.

[0049] In actual application, although the keyless entry system (including the smart key and the vehicle-mounted base station) is calibrated on the whole vehicle before the vehicle is delivered, due to the interference of the metal in the vehicle support, controller, etc., or the difference of the smart key hardware, or the change of the environmental temperature and humidity, or the aging of the coil and other devices, the directly measured low-frequency signal strength will change. Therefore, with the change of the RSSI value received by the smart key, the accurate positioning of the smart key will be affected, that is, the measurement accuracy of the RSSI value is an important factor affecting the accurate positioning of the smart key.

[0050] The intelligent key (for example, adopting chip ATA5702) has an RSSI measurement function, which can measure the received signal strength on the x-axis coil, y-axis coil and z-axis coil. There are two RSSI value measurement modes: an external measurement mode and an internal measurement mode. The external measurement mode is the RSSI value directly measured by the intelligent key after the vehicle-mounted base station drives the low-frequency antenna to transmit a low-frequency signal; the internal measurement mode is the fixed signal RSSI value generated by the built-in excitation source of the chip, which can be used for environmental error compensation according to the characteristics of the chip. Therefore, it is necessary to simultaneously start the internal measurement mode and the external measurement mode of the intelligent key to improve the measurement accuracy of the RSSI value.

[0051] In some embodiments, as shown in FIG. 1, Figure 3 Step S1 includes:

[0052] Placing the low-frequency antenna of the intelligent key and the vehicle-mounted base station in an electromagnetic shielding box;

[0053] Setting the intelligent key to the internal measurement mode;

[0054] Driving the low-frequency antenna of the vehicle-mounted base station to transmit a low-frequency signal by the vehicle-mounted base station multiple times with a fixed drive current;

[0055] The intelligent key receives and measures the magnetic field strength multiple times;

[0056] Taking the average of the magnetic field strength measured multiple times to obtain a set of internal reference values of the magnetic field strength for environmental error compensation, and storing them in the EEPROM of the intelligent key.

[0057] As shown in FIG. 2, Figure 2 Each low-frequency antenna has its own magnetic field coverage area (effective detection area, shaded part). According to the inverse square law, the magnetic field strength decreases with the increase of distance. Therefore, it is necessary to set a boundary according to the actual application. Before the vehicle is shipped, a calibration is performed on the whole vehicle, that is, the three low-frequency antennas in the vehicle are driven in turn by the vehicle-mounted base station, the working current of the antenna is adjusted, and the magnetic field is covered as much as possible throughout the vehicle space; then the three low-frequency antennas outside the vehicle are driven in turn, the drive current of the antenna is adjusted, and the magnetic field is covered as much as possible to the preset distance (for example, about 1.5 meters) outside the vehicle space.

[0058] After completing the whole vehicle calibration, the intelligent key is used to measure the strength of the field inside and outside the vehicle, the RSSI value at the boundary of the effective detection area is measured, and the value is set as the threshold of the effective detection area. The area with an RSSI value greater than the threshold is the effective detection area of the corresponding low-frequency antenna. The effective detection area can be divided into inside and outside the vehicle through the magnetic field strength threshold. After accurately measuring the RSSI value, it is determined whether the intelligent key is inside or outside the vehicle according to the corresponding relationship between the RSSI value and the distance.

[0059] The magnetic field strength close to the inner side of the door is set as the threshold of the in-vehicle effective detection area boundary , so that the in-vehicle effective detection area is limited to the in-vehicle space. Similarly, the magnetic field strength at a preset distance (for example, about 1.5 meters) outside the vehicle is set as the threshold of the out-vehicle effective detection area boundary . In addition, the magnetic field strength of a certain range of space area in the vehicle is within the threshold range of the out-vehicle effective detection area, that is, there is an overlapping area between the out-vehicle effective detection area and the in-vehicle effective detection area.

[0060] In some embodiments, as shown in Figure 4 , step S2 includes:

[0061] The position close to the inner side of the door is set as the in-vehicle boundary, and the preset distance outside the vehicle is set as the out-vehicle boundary;

[0062] The magnetic field strength at the in-vehicle boundary is measured by the smart key and set as the threshold of the in-vehicle effective detection area boundary;

[0063] The magnetic field strength at the out-vehicle boundary is measured by the smart key and set as the threshold of the out-vehicle effective detection area boundary.

[0064] In some embodiments, in step S2, the threshold of the in-vehicle effective detection area boundary and the threshold of the out-vehicle effective detection area boundary are saved to the FLASH of the vehicle-mounted base station MCU.

[0065] In some embodiments, step S2 further includes a low-frequency antenna calibration step:

[0066] The in-vehicle low-frequency antennas are driven by the vehicle-mounted base station in sequence, and the working current of the in-vehicle low-frequency antennas is adjusted to cover the entire in-vehicle space with the magnetic field;

[0067] The out-vehicle low-frequency antennas are driven by the vehicle-mounted base station in sequence, and the working current of the out-vehicle low-frequency antennas is adjusted to cover the preset distance outside the vehicle with the magnetic field.

[0068] Accurate positioning is one of the cores of the keyless entry system. The positioning of the keyless entry system includes two aspects: one is to accurately determine whether the key is in the effective detection area. The second is to accurately determine whether the key is in the vehicle or outside the vehicle.

[0069] In some embodiments, as shown in Figure 5 , step S3 includes:

[0070] The in-vehicle low-frequency antennas are driven by the vehicle-mounted base station to send low-frequency signals, and after the smart key switches between the external measurement mode and the internal measurement mode, the measurement value A is obtained through error compensation calculation;

[0071] The smart key obtains the measurement value B through error compensation calculation after switching between the external measurement mode and the internal measurement mode.

[0072] The vehicle-mounted base station compares the measurement value A, the measurement value B, the in-vehicle effective detection area boundary threshold value, and the out-of-vehicle effective detection area boundary threshold value to obtain a positioning result.

[0073] In some embodiments, step S3 further includes that the smart key transmits the measurement value A and the measurement value B to the vehicle-mounted base station through high frequency.

[0074] In some embodiments, the positioning result in step S3 includes:

[0075] If the measurement value A is greater than the in-vehicle effective detection area boundary threshold value and the measurement value B is less than the out-of-vehicle effective detection area boundary threshold value, the smart key is in the vehicle (indicating that the smart key is in the in-vehicle effective detection area and not in the out-of-vehicle effective detection area);

[0076] If the measurement value A is greater than the in-vehicle effective detection area boundary threshold value and the measurement value B is greater than the out-of-vehicle effective detection area boundary threshold value, the smart key is in the vehicle (indicating that the smart key is in the in-vehicle / out-of-vehicle effective detection area overlap region);

[0077] If the measurement value A is less than the in-vehicle effective detection area boundary threshold value and the measurement value B is greater than the out-of-vehicle effective detection area boundary threshold value, the smart key is out of the vehicle (indicating that the smart key is in the out-of-vehicle effective detection area and not in the in-vehicle effective detection area);

[0078] If the measurement value A is less than the in-vehicle effective detection area boundary threshold value and the measurement value B is less than the out-of-vehicle effective detection area boundary threshold value, the smart key is not in the effective detection area (indicating that the smart key is not in the out-of-vehicle effective detection area and not in the in-vehicle effective detection area).

[0079] In some embodiments, in step S3, the vehicle-mounted base station is provided with three in-vehicle low-frequency antennas and three out-of-vehicle low-frequency antennas, and step S3 includes:

[0080] The vehicle-mounted base station drives the three in-vehicle low-frequency antennas to send low-frequency signals;

[0081] The smart key obtains the measurement values of the three in-vehicle low-frequency antennas through error compensation calculation after switching between the external measurement mode and the internal measurement mode, and takes the maximum value of the measurement values of the three in-vehicle low-frequency antennas as the measurement value A.

[0082] The vehicle-mounted base station drives the three out-of-vehicle low-frequency antennas to send low-frequency signals respectively;

[0083] ​The intelligent key obtains the measurement values of the three low-frequency antennas outside the vehicle through error compensation calculation after switching between the external measurement mode and the internal measurement mode Set as measurement value B

[0084] The boundary threshold of the effective detection area inside the vehicle is The boundary threshold of the effective detection area outside the vehicle is The positioning result is obtained by comparing and judging 、 、 、

[0085] > And < , which indicates that the intelligent key is in the effective detection area inside the vehicle and not in the effective detection area outside the vehicle, and the intelligent key is inside the vehicle

[0086] > And > , which indicates that the intelligent key is in the overlapping area of the effective detection area inside / outside the vehicle, and the intelligent key is inside the vehicle

[0087] < And > , which indicates that the intelligent key is in the effective detection area outside the vehicle and not in the effective detection area inside the vehicle, and the intelligent key is outside the vehicle

[0088] < And < , which indicates that the intelligent key is not in the effective detection area inside / outside the vehicle, and the intelligent key is not in the effective detection area.

[0089] In some embodiments, after the intelligent key switches between the external measurement mode and the internal measurement mode, the measurement value step is obtained through error compensation calculation

[0090] A set of internal reference values of magnetic field strength is set as 、 、 ;

[0091] The intelligent key is set to the external measurement mode, and a set of magnetic field strengths 、 、 are obtained by completing external measurement

[0092] ​The smart key is set to the internal measurement mode and a set of magnetic field strengths is measured again , , ;

[0093] The measurement value after error compensation is:

[0094] = + ( - ),

[0095] = + ( - ),

[0096] = + ( - ),

[0097] = .

[0098] Example embodiments have been disclosed herein and, although the specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation. In some instances, it will be apparent to those skilled in the art that features, characteristics or elements described with respect to a particular embodiment can be used, individually or in combination, with other embodiments unless otherwise specifically stated. Accordingly, it will be understood that various changes in form and details can be made without departing from the scope of the present disclosure as set forth in the appended claims.

Claims

1. A method for rapid location of a smart key, characterized in that, include: Step S1, optimize the accuracy of magnetic field strength measurement: use the internal measurement mode of the smart key terminal to measure the magnetic field strength and obtain a set of internal reference values ​​of magnetic field strength for environmental error compensation; Step S2, set magnetic field strength threshold: Use the smart key to measure the magnetic field strength at the boundary inside the vehicle and the magnetic field strength at the boundary outside the vehicle, and set the magnetic field strength at the boundary inside the vehicle and the magnetic field strength at the boundary outside the vehicle as the boundary threshold of the effective detection area inside the vehicle and the boundary threshold of the effective detection area outside the vehicle, respectively. Step S3, Location determination based on magnetic field strength: Low-frequency signals are sent by the in-vehicle low-frequency antenna and the out-of-vehicle low-frequency antenna of the vehicle base station. The magnetic field strength measured by the smart key is obtained by error compensation to obtain measurement value A and measurement value B. Measurement value A, measurement value B, the boundary threshold of the effective detection area inside the vehicle and the boundary threshold of the effective detection area outside the vehicle are compared to determine the location result.

2. The method according to claim 1, wherein, Step S1 includes: The smart key and the low-frequency antenna of the vehicle base station are placed in an electromagnetic shielding box. Set the smart key to internal measurement mode; The vehicle-mounted base station drives the low-frequency antenna of the vehicle-mounted base station to transmit low-frequency signals multiple times with a fixed driving current. The smart key received and measured the magnetic field strength multiple times; The average value of the magnetic field strength measured multiple times is used to obtain a set of internal reference values ​​for magnetic field strength for environmental error compensation, and these values ​​are stored in the EEPROM of the smart key.

3. The method according to claim 1, wherein, Step S2 includes: Set the position closest to the inside of the car door as the inner boundary of the vehicle, and set the preset distance outside the vehicle as the outer boundary of the vehicle. The smart key is used to measure the magnetic field strength at the boundary of the vehicle interior and set it as the boundary threshold of the effective detection area inside the vehicle. The smart key is used to measure the magnetic field strength at the vehicle's outer boundary and set it as the threshold for the effective detection area outside the vehicle.

4. The method according to claim 3, wherein, In step S2, the effective detection area boundary thresholds inside the vehicle and the effective detection area boundary thresholds outside the vehicle are saved to the FLASH of the vehicle base station MCU.

5. The method according to claim 3, wherein, The step S2 is preceded by a low-frequency antenna calibration step: By sequentially driving the in-vehicle low-frequency antenna through the vehicle-mounted base station, the operating current of the in-vehicle low-frequency antenna is adjusted, and the magnetic field covers the entire in-vehicle space. By sequentially driving the external low-frequency antenna through the vehicle-mounted base station and adjusting the operating current of the external low-frequency antenna, the magnetic field is extended to a preset distance in the external space.

6. The method according to claim 3, wherein, Step S3 includes: The vehicle base station drives the in-vehicle low-frequency antenna to send low-frequency signals. After the smart key switches between external measurement mode and internal measurement mode, it calculates the measurement value A through error compensation. The vehicle-mounted base station drives the external low-frequency antenna to send low-frequency signals. After the smart key switches between external and internal measurement modes, it calculates the measurement value B through error compensation. The vehicle-mounted base station compares and judges the measurement value A, measurement value B, the effective detection area boundary threshold inside the vehicle, and the effective detection area boundary threshold outside the vehicle to obtain the positioning result.

7. The method according to claim 6, wherein, Step S3 also includes: the smart key transmits the measurement value A and the measurement value B to the vehicle base station via high frequency.

8. The method according to claim 6, wherein, The location results in step S3 include: If the measured value A is greater than the effective detection area boundary threshold inside the vehicle and the measured value B is less than the effective detection area boundary threshold outside the vehicle, the smart key is inside the vehicle. If the measured value A is greater than the boundary threshold of the effective detection area inside the vehicle and the measured value B is greater than the boundary threshold of the effective detection area outside the vehicle, the smart key is inside the vehicle. If the measured value A is less than the effective detection area boundary threshold inside the vehicle and the measured value B is greater than the effective detection area boundary threshold outside the vehicle, the smart key is outside the vehicle. If the measured value A is less than the threshold of the effective detection area inside the vehicle and the measured value B is less than the threshold of the effective detection area outside the vehicle, the smart key is not within the effective detection area.

9. The method according to claim 3, wherein, In step S3, the vehicle-mounted base station is equipped with three in-vehicle low-frequency antennas and three external low-frequency antennas. Step S3 includes: The vehicle-mounted base station drives three in-vehicle low-frequency antennas to transmit low-frequency signals. After switching between external and internal measurement modes, the smart key calculates the measurement values ​​of the three in-vehicle low-frequency antennas through error compensation, and then takes the maximum value of the three measurements. Let's set the measured value as A; The vehicle-mounted base station drives three external low-frequency antennas to transmit low-frequency signals. After switching between external and internal measurement modes, the smart key calculates the measurement values ​​of the three external low-frequency antennas through error compensation, and then takes the maximum value of the three measurements. Let's set it as measurement value B; The effective detection area boundary threshold inside the vehicle is The effective detection area boundary threshold outside the vehicle is Through the , , , The location result is obtained through comparison and judgment: > and < The smart key is inside the car; > and > The smart key is inside the car; < and > The smart key is outside the car; < and < The smart key is not within the effective detection range.

10. The method according to claim 6 or 9, wherein, After switching between external and internal measurement modes, the smart key obtains the measurement value through error compensation calculation. The steps are as follows: Set a set of internal reference values ​​for magnetic field strength. , , ; Set the smart key to external measurement mode and complete the external measurement to obtain a set of magnetic field strengths. , , ; The smart key was set to internal measurement mode, and another set of magnetic field strength measurements were obtained. , , ; Measurement value after error compensation for: = + ( - )， = + ( - )， = + ( - )， = 。

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