A method and device for three-dimensional positioning of a smart key of a vehicle

Abstract

The intelligent key three-dimensional positioning method and positioning device of the vehicle of the present application utilize the existing BLE TPMS system as a locator and a master node, and a magnetometer in the master node, combine BLE AOA seeking technology, BLE RSSI and the position angle information output by the magnetometer, and adopt a designed positioning algorithm to realize three-dimensional positioning of the intelligent key. The present application can improve the positioning accuracy of the key, the accuracy of the in-vehicle and out-vehicle discrimination, and simplify the key positioning system to reduce the system cost.

Description

TECHNICAL FIELD

[0001] The present application relates to an intelligent positioning system, more particularly, to a three-dimensional positioning method and device of an intelligent key of a vehicle. BACKGROUND

[0002] Tire pressure monitoring system (TPMS) is a system that monitors the air pressure in vehicle tires in real time and alerts the driver of low tire pressure or loss of air pressure to ensure safe driving. The wireless TPMS consists of a wireless communication module and a receiver. The wireless communication module uses a temperature and pressure sensor and a wireless transceiver inside the tire to send data to the receiver, which monitors the pressure and temperature of each tire in real time and displays the data. When the tire has a leak, the pressure is too high or too low, or the temperature is too high, the receiver will automatically alert and display the tire status to ensure the safety of the vehicle. The system has the characteristics of high cost but good monitoring effect and high accuracy and reliability.

[0003] Passive entry passive start (PEPS) system is a vehicle electronic technology developed in recent years. The vehicle owner only needs to carry the key, without taking it out, to complete the unlocking, locking, starting the vehicle, and other operations, which is convenient for the owner to use the vehicle. The Bluetooth passive entry passive start system developed by combining BLE communication technology and PEPS system eliminates the trouble of searching for the car key and improves the user experience. BLE PEPS usually needs to place a certain number of BLE modules called BLE Locator inside and outside the vehicle body. The BLE Locator receives the receive signal strength indicator (RSSI) and other parameters of the BLE Tags, and processes them with an algorithm to achieve positioning. However, using RSSI can only achieve meter-level positioning, and the positioning accuracy is low, which cannot meet the requirements of PEPS. In addition, arranging more BLE Locators can improve the positioning accuracy of RSSI, but this also increases the system cost.

[0004] In view of the above problems, how to propose a technology that uses the existing tire pressure monitoring system of the vehicle to achieve accurate three-dimensional positioning of the intelligent key and reduce the complexity and cost of the system has become one of the problems that need to be solved by personnel in this technical field. SUMMARY

[0005] Therefore, the application provides a three-dimensional positioning method and device for a smart key of a vehicle, which utilizes an existing tire pressure monitoring system, has high positioning accuracy, low system complexity and low cost, and solves the problems of low positioning accuracy, high system complexity and high cost in the prior art.

[0006] In a first aspect, the application provides a three-dimensional positioning method for a smart key of a vehicle. Four wireless communication modules of a tire pressure monitoring system arranged on surfaces of four wheel hubs of the vehicle serve as four locators. A receiver of the tire pressure monitoring system located in the vehicle serves as a master node. The positions of a center of a circle on which the four wheel hubs are located and the master node are known. The positioning method comprises the following steps:

[0007] The locators communicate with the smart key, and the coordinates of the smart key in a horizontal two-dimensional coordinate system and a vertical two-dimensional coordinate system are calculated by measuring the arrival angle of the smart key relative to the locators.

[0008] The three-dimensional coordinates of the smart key are obtained according to the coordinates of the smart key in the horizontal two-dimensional coordinate system and the vertical two-dimensional coordinate system.

[0009] The positioning method further comprises judging whether the locators reach preset positions of the circle on which the wheel hubs are located, wherein the preset positions are at least one. When the locators reach the preset positions, the locators communicate with the smart key.

[0010] Preferably, whether the locators reach the preset positions of the circle on which the wheel hubs are located is judged by measuring the magnetic field intensity by a magnetometer.

[0011] Preferably, judging whether the locators reach the preset positions comprises the following steps:

[0012] The horizontal component and the vertical component of the magnetic field intensity are measured by the magnetometer.

[0013] The included angle between the magnetic field intensity and the coordinate axis of the surface on which the wheel hubs are located is calculated.

[0014] Whether the included angle is equal to a preset angle is judged.

[0015] When the included angle is equal to the preset angle, the locators reach the preset positions. When the included angle is not equal to the preset angle, the locators do not reach the preset positions.

[0016] Preferably, the preset angles are four: the first preset angle is 0°, the second preset angle is 90°, the third preset angle is 180°, and the fourth preset angle is -90°; wherein the preset positions are also four, the first preset position corresponds to the first preset angle, the second preset position corresponds to the second preset angle; the third preset position corresponds to the third preset angle; and the fourth preset position corresponds to the fourth preset angle.

[0017] Preferably, the position of the key in a horizontal two-dimensional coordinate system is determined according to the first preset position and the second preset position, and the position of the key in a vertical two-dimensional coordinate system is determined according to the third preset position and the fourth preset position.

[0018] Preferably, the positioning method further comprises: averaging the coordinates of the key in a three-dimensional coordinate system obtained by the four locators respectively to obtain the three-dimensional coordinates of the key.

[0019] Preferably, the positioning method further comprises: judging whether the key is in the vehicle body according to the three-dimensional coordinates of the key.

[0020] Preferably, the process of judging whether the key is in the vehicle body comprises:

[0021] According to the coordinates of the key in the three-dimensional coordinate system, the distance between the master node and the key is calculated, marked as the first distance;

[0022] According to the received signal strength corresponding to the key signal transmitted by the master node, the distance between the master node and the key is calculated, marked as the second distance;

[0023] According to the first distance, the second distance and the limited coordinate range of the vehicle body, it is judged whether the key is in the vehicle body.

[0024] Preferably, according to the first distance, the second distance and the limited coordinate range of the vehicle body, it is judged whether the key is in the vehicle body, which specifically comprises the following steps:

[0025] It is judged whether the difference between the first distance and the second distance is within an acceptable distance threshold range;

[0026] When the difference is not within the distance threshold range, the position of the key is repositioned;

[0027] When the difference is within the distance threshold range, it is judged whether the coordinates of the key are within the limited coordinate range of the vehicle body;

[0028] When the coordinates of the key are within the limited coordinate range, it is judged that the key is in the vehicle body; otherwise, it is judged that the key is outside the vehicle body.

[0029] Preferably, the second distance is calculated according to the following formula:

[0030]

[0031] wherein d2 is the second distance, d_ref is a reference distance, RSSI_ref is a signal strength corresponding to the key transmission signal collected by the master node at the reference distance, RSSI is a signal strength corresponding to the key transmission signal collected by the master node at the second distance, and a is a path loss exponent.

[0032] Preferably, the process of determining whether the key is inside the vehicle body comprises:

[0033] According to the coordinates of the key and the master node in a three-dimensional coordinate system, the angle of arrival of the key relative to the master node is calculated, denoted as a first angle;

[0034] The broadcast information of the in-phase component and the quadrature component transmitted by the key is collected by the master node to determine the angle of arrival of the key relative to the master node, denoted as a second angle.

[0035] According to the first angle, the second angle, and the defined coordinate range of the vehicle body, it is determined whether the key is inside the vehicle body.

[0036] Preferably, according to the first angle, the second angle, and the defined coordinate range of the vehicle body, it is determined whether the key is inside the vehicle body, specifically comprising the following steps:

[0037] It is determined whether the difference between the first angle and the second angle is within an acceptable angle threshold range;

[0038] When the difference is not within the angle threshold range, the position of the key is repositioned;

[0039] When the difference is within the angle threshold range, it is determined whether the coordinates of the key are within the defined coordinate range of the vehicle body;

[0040] When the coordinates of the key are within the defined coordinate range, it is determined that the key is inside the vehicle body; otherwise, it is determined that the key is outside the vehicle body.

[0041] Preferably, the locator comprises an antenna array, and the measurement of the angle of arrival comprises the following steps:

[0042] The key transmits a broadcast containing measurement information of the in-phase component and the quadrature component to the locator;

[0043] The locator samples the broadcast information of the in-phase component and the quadrature component by switching different antennas;

[0044] According to the sampled broadcast information of the in-phase component and the quadrature component, the phase difference of the key reaching different antennas of the locator is calculated;

[0045] According to the phase difference, the real-time angle of arrival of the key relative to the locator is calculated.

[0046] Preferably, the phase difference of the key reaching different antennas of the locator is calculated by the following formula:

[0047]

[0048] wherein φ_diff represents the phase difference, I1 represents the in-phase component received by a first antenna in the antenna array of the locator, I2 represents the in-phase component received by a second antenna in the antenna array of the locator, Q1 represents the quadrature component received by the first antenna in the antenna array of the locator, and Q2 represents the quadrature component received by the second antenna in the antenna array of the locator.

[0049] Preferably, the angle of arrival of the key relative to the main node is calculated according to the phase difference by the following formula:

[0050]

[0051] wherein θ represents the angle of arrival, φ_diff represents the phase difference, d represents the distance between the two antennas of the locator, and λ represents the wavelength of the electromagnetic field propagating the broadcast, wherein d <= λ / 2.

[0052] In a second aspect, the embodiments of the present application further provide a three-dimensional positioning device for a smart key of a vehicle, comprising: a plurality of locators, a main node, and a key.

[0053] The locators and the main node each comprise a sending module and a receiving module, and the key comprises a sending module; wherein the sending module sends positioning information, and the receiving module receives the positioning information.

[0054] The main node further comprises a data processing module, which obtains the coordinates of the key in a horizontal two-dimensional coordinate system and a vertical two-dimensional coordinate system by calculating the angle of arrival of the key relative to the locators, and obtains the three-dimensional coordinates of the key according to the coordinates in the horizontal two-dimensional coordinate system and the vertical two-dimensional coordinate system.

[0055] Preferably, four wireless communication modules of the tire pressure monitoring system arranged on the surfaces of four wheel hubs of the automobile serve as four locators, and a receiver of the tire pressure monitoring system serves as a master node in the automobile, wherein the wireless communication modules and the receiver comprise antenna arrays.

[0056] Preferably, the locator further comprises a magnetometer, and the data processing module determines whether the locator reaches the preset position according to a magnetic field intensity measured by the magnetometer.

[0057] Preferably, the data processing module calculates an angle between the magnetic field intensity and a coordinate axis according to a horizontal component and a vertical component of the magnetic field intensity measured by the magnetometer, and determines whether the locator reaches the preset position.

[0058] Preferably, the data processing module determines a coordinate of the key in a horizontal two-dimensional coordinate system according to an arrival angle of the key relative to two preset positions of the locator in a horizontal direction of the surface on which the wheel hub is located, and determines a coordinate of the key in a vertical two-dimensional coordinate system according to an arrival angle of the key relative to two preset positions of the locator in a vertical direction of the surface on which the wheel hub is located.

[0059] Preferably, the data processing module calculates a distance between the master node and the key, marked as a first distance, according to the coordinates of the key and the master node in the three-dimensional coordinate system, wherein the coordinate of the master node in the three-dimensional coordinate system is known.

[0060] The data processing module calculates a distance between the master node and the key, marked as a second distance, according to the signal strength of the signal transmitted by the key and collected by the master node.

[0061] The data processing module determines whether the key is in the automobile according to the first distance, the second distance, and a limited coordinate range of the automobile body.

[0062] Preferably, the data processing module calculates the second distance by the following formula:

[0063]

[0064] wherein d2 is the second distance, d ref is a reference distance, RSSI ref is the signal strength of the signal transmitted by the key and collected by the receiving module of the master node at the reference distance d ref RSSI is the signal strength of the signal transmitted by the key and collected by the receiving module of the master node at the second distance, and a is a path loss index.

[0065] Preferably, the data processing module calculates an arrival angle of the key relative to the master node, denoted as a first angle, according to the coordinates of the key and the master node in a three-dimensional coordinate system, wherein the coordinates of the master node in the three-dimensional coordinate system are known.

[0066] The data processing module calculates an arrival angle of the key relative to the master node, denoted as a second angle, according to the broadcast information of the in-phase component and the quadrature component sent by the key and collected by the master node.

[0067] The data processing module determines whether the key is in the vehicle body according to the first angle, the second angle, and a limited coordinate range of the vehicle body.

[0068] Preferably, the data processing module calculates the arrival angle according to the following formula:

[0069]

[0070] wherein θ represents the arrival angle, represents a phase difference of the electromagnetic wave sent by the sending module and received by two of the antenna array of the receiving module, d represents a distance between the two antennas of the antenna array of the receiving module, and λ represents a wavelength of the electromagnetic field sent by the sending module, wherein

[0071] Preferably, the data processing module calculates the phase difference of the electromagnetic wave sent by the sending module and received by two of the antenna array of the receiving module according to the following formula:

[0072]

[0073] wherein, represents the phase difference, I1 represents the in-phase component sent by the sending module and received by a first antenna of the antenna array of the receiving module, I2 represents the in-phase component sent by the sending module and received by a second antenna of the antenna array of the receiving module, Q1 represents the quadrature component sent by the sending module and received by the first antenna of the antenna array of the receiving module, and Q2 represents the quadrature component sent by the sending module and received by the second antenna of the antenna array of the receiving module.

[0074] Compared with the prior art, the vehicle intelligent key positioning method and the positioning device have the following advantages: the vehicle intelligent key positioning method and the positioning device utilize the existing BLE TPMS system as a locator and a master node, and a magnetometer in the master node, combine BLE AOA seeking technology, BLE RSSI and position angle information output by the magnetometer, and adopt a designed three-dimensional decomposition positioning algorithm to realize positioning of the intelligent key and discrimination between inside and outside of the vehicle. BRIEF DESCRIPTION OF DRAWINGS

[0075] The above and other objects, features and advantages of the present application will become more apparent from the following description of embodiments of the present application taken in conjunction with the accompanying drawings, in which:

[0076] Figure 1 FIG. 1 is a schematic diagram of a vehicle intelligent key three-dimensional positioning device according to the present application;

[0077] Figure 2 FIG. 2 is a flowchart of a vehicle intelligent key three-dimensional positioning method according to the present application;

[0078] Figure 3 FIG. 3 is a schematic diagram of a principle of angle of arrival positioning according to the present application;

[0079] Figure 4 FIG. 4 is a schematic diagram of a magnetic field strength measured by a magnetometer according to the present application;

[0080] Figure 5 FIG. 5 is a schematic diagram of a two-dimensional space angle of arrival according to the present application;

[0081] Figure 6 FIG. 6 is a schematic diagram of a three-dimensional space angle of arrival according to the present application;

[0082] Figure 7 FIG. 7 is a schematic diagram of a principle of decomposing a three-dimensional space into a two-dimensional space according to the present application;

[0083] Figure 8 FIG. 8 is a schematic diagram of a coordinate range of a vehicle body according to the present application. DETAILED DESCRIPTION

[0084] The present application is described below based on embodiments, but the present application is not limited to only these embodiments. In the following detailed description of the present application, some specific details are described in detail. The present application can also be understood without these details by those skilled in the art. In order to avoid obscuring the essence of the present application, well-known methods, processes, procedures, elements and circuits are not described in detail.

[0085] Moreover, those skilled in the art will appreciate that the accompanying drawings provided herein are for illustrative purposes and are not necessarily drawn to scale.

[0086] The embodiment provides a three-dimensional positioning device and method for an intelligent key of a vehicle. Figure 1 As shown in the drawings, the positioning device comprises four locators, a master node and a key; the positioning device uses four wireless communication modules of a TPMS (Tire Pressure Monitoring System) provided on surfaces of four wheel hubs of the vehicle as the four locators, and the wireless communication modules comprise an antenna array; a receiver in the TPMS in the vehicle serves as the master node and also comprises an antenna array.

[0087] The locator and the master node each comprise a sending module and a receiving module, and the key comprises a sending module; the sending module sends positioning information, and the receiving module receives the positioning information; the master node further comprises a data processing module, which processes the received data to calculate position information of the locator and the master node; the sending module and the receiving module each support a Bluetooth 5.1 protocol, so that the intelligent key positioning device supports an AOA (Angel of Arrival) positioning function; the locator further comprises a magnetometer, which is used to obtain position information of the locator on a surface of the wheel hub; and the positioning method is implemented based on the positioning device. Figure 2 The positioning method comprises the following steps:

[0088] S1: determining whether the locator reaches a preset position on a surface of the wheel hub, wherein the preset position is at least one;

[0089] Specifically, the locator determines whether it is at a preset position on a circle of the wheel hub by measuring a magnetic field strength by the magnetometer, and the method comprises the following steps:

[0090] S11: measuring a horizontal component and a vertical component of the magnetic field strength by the magnetometer;

[0091] S12: calculating an included angle between the magnetic field strength and a horizontal coordinate axis in a coordinate system of the surface of the wheel hub;

[0092] S13: determining whether the included angle is equal to a preset angle; wherein the preset angle is four: a first preset angle a1 is 0°, a second preset angle a2 is 180°, a third preset angle a3 is 90°, and a fourth preset angle a4 is -90°.

[0093] S14: when the included angle is equal to the preset angle, the positioner reaches the preset position; when the included angle is not equal to the preset value, the positioner does not reach the preset position;

[0094] Specifically, the first preset position S1 and the first preset angle a1 correspond, the second preset position S2 and the second preset angle a2 correspond; the third preset position S3 and the third preset angle a3 correspond; the fourth preset position S4 and the fourth preset angle a4 correspond; the first preset position S1 and the second preset position S2 are located in a horizontal plane, the third preset position S3 and the fourth preset position S4 are located in a vertical plane, and the coordinates of the first preset position S1 to the fourth preset position S4 of the four positioners in a three-dimensional coordinate system can be obtained according to the center of the circle where the four wheel hubs are located and the radius of the wheel hub; in this embodiment, if not otherwise specified, the three-dimensional coordinates refer to the coordinates in a coordinate system with the center of the left front wheel hub as the coordinate origin, the X-axis passing through and pointing to the center of the left rear wheel hub, the Y-axis passing through and pointing to the center of the right front wheel hub, and the Z-axis perpendicular to the XOY plane upward.

[0095] It should be noted that the first preset angle a1 to the fourth preset angle a4 include but are not limited to those listed in this embodiment, and any first preset angle a1 to the fourth preset angle a4 that can enable the corresponding first preset position S1 and the second preset position S2 to be located in a horizontal plane and the third preset position S3 and the fourth preset position S4 to be located in a vertical plane all satisfy this embodiment; in addition, after the step S11, the positioner sends the horizontal component and the vertical component to the data processing module through the sending module thereof, and the steps S12, S13 and S14 are all completed by the data processing module.

[0096] It should be further noted that, as Figure 4As shown, the coordinate system of the wheel hub is established with the center of the wheel hub as the origin. The positioner including the magnetometer is mounted on the surface of the wheel hub. With the rotation of the wheel, the position of the positioner relative to the vehicle body is unpredictable, i.e., the accurate coordinates of the positioner cannot be obtained. Since the coordinate error caused by the wheel diameter cannot be ignored, the positioner cannot be accurately positioned even if the value of AOA is measured. In order to solve the above-mentioned coordinate error problem, the two-axis magnetometer is used to obtain the position information of the positioner during the rotation of the wheel. Since the magnetic field distribution of the vehicle body is relatively complex, the vehicle-mounted electronic equipment, engine, and ferromagnetic materials such as rigid vehicle body will all generate corresponding magnetic fields. In addition, the earth's magnetic field will also be coupled with the vehicle body magnetic field. Therefore, it is very difficult to accurately model the space of the vehicle body magnetic field. The scheme of the embodiment only uses the magnetometer to measure the magnetic field distribution around the tire to realize the preliminary positioning of the positioner, so it is not necessary to consider the distribution model of the vehicle body magnetic field. Therefore, only the magnetic field strength measured by the magnetometer during the rotation of the tire needs to be considered, and the positioning problem of the positioner is simplified. Since the absolute strength of the magnetic field is not the main factor for realizing positioning in the present application, it can be considered that the magnetic field strength measured by the magnetometer during the rotation of the tire is a vector, and the total value is approximately a fixed value, as shown in the following formula: As shown, the horizontal and vertical components of the magnetic field strength on the surface of the wheel hub at any time can be represented as: Figure 4

[0097]

[0098] In the above formula, H is the size of the magnetic field strength; and α is the angle between the magnetic field strength and the X axis.

[0099] Since the tire rotates in a circular manner, the angle α will change periodically. Therefore, the horizontal and vertical components measured by the magnetometer can be further represented as:

[0100]

[0101] During the rotation of the wheel, the horizontal and vertical components of the magnetic field strength are continuously collected by the magnetometer, and the angle α between the magnetic field strength and the X axis is calculated. It can be found that during the rotation of the wheel, there is an α corresponding to the position of the positioner on the tire. Therefore, α can uniquely represent the position of the positioner, and the spatial coordinate value of the positioner can be calculated. However, the mapping relationship between the position of the positioner on the tire and α cannot be directly obtained, so the value of α corresponding to the position of the positioner at some specific positions needs to be measured in advance.

[0102] ​​According to the value of a, the coordinates L'(x b , y b ) of each of the locators in the two-dimensional coordinate system with the center of the corresponding wheel hub as the origin can be obtained, where r is the radius of the wheel hub,

[0103]

[0104] Correspondingly, the coordinates of the first preset position S1 to the fourth preset position S4 in the two-dimensional coordinate system with the center of the wheel hub as the origin are (r, 0), (-r, 0), (0, r), and (0, -r); the coordinates L'(x b , y b ) of each of the locators in the plane where the corresponding wheel hub is located are converted into the coordinates in a three-dimensional coordinate system with the center of the wheel hub as the origin, the X axis passing through the center of the left rear wheel hub, the Y axis passing through the center of the right front wheel hub, and the Z axis being perpendicular to the XOY plane and upward, so that when the locator is in the first preset position S1 to the fourth preset position S4, the coordinates in the three-dimensional coordinate system with the center of the wheel hub as the origin are (r, 0, 0), (-r, 0, 0), (0, 0, r), and (0, 0, -r), respectively.

[0105] S2: When the locator reaches each of the preset positions of the wheel hub circle, communicate with the key, and calculate the coordinates of the key in the horizontal two-dimensional coordinate system and the vertical two-dimensional coordinate system, respectively, by measuring the arrival angle of the key relative to the locator; specifically, the position of the key in the horizontal two-dimensional coordinate system is determined according to the first preset position S1 and the second preset position S2, and the position of the key in the vertical two-dimensional coordinate system is determined according to the third preset position S3 and the fourth preset position S4.

[0106] Specifically, when the locator reaches the preset position, measuring the arrival angle of the key relative to the locator includes the following steps:

[0107] S21: The key sends the broadcast of the measurement information containing the in-phase component and the quadrature component to the locator through the sending module thereof;

[0108] S22: The receiving module of the locator samples the broadcast information of the in-phase component and the quadrature component by switching different antennas, and sends the collected information to the master node through the sending module thereof;

[0109] S23: The receiving module of the master node receives the sampled broadcast information, and the data processing module of the master node calculates the phase difference of the key reaching different antennas of the locator according to the sampled broadcast information of the in-phase component and the quadrature component

[0110] Specifically, the phase difference of the key reaching the different antennas A0 and A1 of the locator is calculated by the following formula

[0111]

[0112] wherein, I1 represents the in-phase component received by the first antenna in the locator receiving module, I2 represents the in-phase component received by the second antenna in the locator receiving module, Q1 represents the quadrature component received by the first antenna in the locator receiving module, and Q2 represents the quadrature component received by the second antenna in the locator receiving module.

[0113] S24: The data processing module calculates the phase difference according to the phase difference S24: The data processing module calculates the phase difference according to the phase difference

[0114] Specifically, the arrival angle is calculated by the following formula:

[0115]

[0116] wherein, as shown in the following formula: Figure 5 represents the phase difference caused by the distance e when the information sent by the sending module of the key reaches the first antenna and the second antenna in sequence, θ represents the arrival angle, d represents the distance between the first antenna A0 and the second antenna A1 of the locator, and λ represents the wavelength of the electromagnetic field of the sent broadcast, wherein

[0117] S25: The data processing module calculates the position of the key in the horizontal two-dimensional coordinate system according to the arrival angle of the key relative to the locator when the positioning point is located at the first preset position S1 and the second preset position S2, and calculates the position of the key in the vertical two-dimensional coordinate system according to the arrival angle of the key relative to the locator when the positioning point is located at the third preset position S3 and the fourth preset position S4.

[0118] Specifically, according to the positioning principle in the XOY plane as shown in the following formula: Figure 3 , it can be known that the coordinates S1(x1, y1) and S2(x2, y2) of the two points S1 and S2 and the arrival angles θ1 and θ2 of the two points reaching the third point p(x p ,y p ) satisfy the following formula:

[0119]

[0120] Therefore, the coordinates of the third point p(x p ,y p ) can be obtained.​

[0121]

[0122] Similarly, given the coordinates of two points S3 and S4 in the YOZ plane, S3(y3,z3) and S4(y4,z4), and the angles θ3 and θ4 from these two points to the third point p, we can find the coordinates p(y3,z3) of point P in the YOZ plane. p ,z p ).

[0123] It should be noted that the arrival angles θ1 and θ2 are the arrival angles in a two-dimensional plane where points S1, S2, and p are coplanar; in practical applications, the device is often in three-dimensional space when estimating the AOA. Figure 6 As shown, a third dimension is added to the two-dimensional case. All positions forming the lateral surfaces of the cone at arrival angle θ can also be the actual positions of the transmitting module. Therefore, in a given continuous space, the lines connecting all points with the same phase difference to the receiving module's position form a cone at angle θ, and the lateral surfaces of the cone represent all possible locations of the transmitting module. Keeping the two arrival angles θ1 and θ2 constant, the trajectory of point P follows the curve of the cone surface (since the curve where the two lateral surfaces intersect is elliptical, the trajectory of this curve is elliptical). Projecting point P onto the horizontal plane along this curve... v’ And P on the vertical plane h’ .like Figure 7 As shown, based on the coordinates of points S1 and S2 and the arrival angles θ1 and θ2 of the key relative to S1 and S2, the actual projection of point P on the horizontal plane is P. v’ The coordinates of S3 and S4; based on the coordinates of points S3 and S4 and the arrival angles θ3 and θ4 of the key relative to S3 and S4, the actual projection on the vertical plane is P. h’ The coordinates. However, since the distance between the key (corresponding to point P) and the locator (corresponding to S1~S4) is usually much greater than half the wavelength (λ / 2), therefore P v P h With P v’ P h’The error between them can be ignored, and as the distance between P point and S1, S2, S3, S4 becomes farther and farther, the error will be sharply reduced, so that the three-dimensional decomposition calculation of P point coordinates can be considered as the real P point coordinates. In this embodiment, the three-dimensional space point coordinates are divided into two parts, i.e. horizontal plane projection coordinates and vertical plane projection coordinates, which has the advantage of reducing the calculation amount of three-dimensional coordinates using three locators in three-dimensional space. When three-dimensional coordinates are calculated using three locators, the calculation formula is complex, which involves many inverse tangent functions and coordinate conversion matrix calculations, and the calculation amount is doubled, which is a great burden for the data processing module. Generally, the data processing module is required to have a DSP core (digital signal processor), which will increase the cost.

[0124] Further need to be explained is that, in Figure 7 , the key coordinates are solved based on the three-dimensional coordinate system with the center of the hub where the locator is located as the origin, four three-dimensional coordinate systems corresponding to four wheels, and the coordinates of the key in each three-dimensional coordinate system are solved by four locators, and then the coordinates of the key in the coordinate systems corresponding to the right front, left rear and right rear hubs are all converted into the coordinates in the three-dimensional coordinate system corresponding to the left front wheel according to the known center coordinates of the circle where the four hubs are located.

[0125] S3: The data processing module obtains the three-dimensional coordinates of the key according to the coordinates of the key in the horizontal two-dimensional coordinate system and the vertical two-dimensional coordinate system.

[0126] It should be noted that, Figure 7 P v’ in the above formula corresponds to the coordinates of P point in XOY plane, and P h’ corresponds to the coordinates of P point in YOZ plane. The coordinates of the two planes are fused to obtain the three-dimensional coordinates (x p ,y p ,z p ) of the key.

[0127] Specifically, the four locators obtain the three-dimensional coordinates (x p1 ,y p1 ,z p1 ), (x p2 ,y p2 ,z p2 ), (x p3 ,y p3 ,z p3 ), (x p4 ,y p4 ,z p4 ) of the key through steps S2 and S3 respectively, and then average to determine the three-dimensional coordinates of the key:

[0128]

[0129] S4: The data processing module determines whether the key is in the vehicle body according to the three-dimensional coordinates of the key; when the key is not in the vehicle body, the positioning process is repeated to reposition the key.

[0130] Specifically, in step S4, determining whether the key is in the vehicle body includes the following steps:

[0131] S41: According to the coordinates of the key in the two-dimensional coordinate system, the distance between the master node and the key is calculated, marked as the first distance d1;

[0132] In this step, the position coordinates of the master node in the three-dimensional coordinate system are known as (x0, y0, z0), and according to the coordinates (x p ,y p ,z p ) of the key obtained in step S3, the first distance d1 can be solved according to the distance formula between two points:

[0133]

[0134] S42: According to the received signal strength RSSI corresponding to the key measured by the master node, the distance between the master node and the key is calculated, marked as the second distance d2; specifically, the second distance d2 is calculated by the following formula.

[0135]

[0136] Thus:

[0137]

[0138] Where d ref is the reference distance, RSSI ref is the received signal strength under the reference distance d ref , and a is the path loss index, which needs to be determined according to the propagation environment, and the second distance d2 is estimated by the above formula.

[0139] S43: According to the first distance d1, the second distance d2, and the limited coordinate range of the vehicle body, it is determined whether the key is in the vehicle body.

[0140] Specifically, step S43 includes the following sub-steps:

[0141] S431: Determine whether the difference between the first distance d1 and the second distance d2 is within the accepted distance threshold d T ; wherein the distance threshold dT This is pre-set according to the test.

[0142] S432: When the difference is not within the distance threshold d T If the difference is within the specified range, then repeat steps S2 to S4 to reposition the key; if the difference is within the specified distance threshold, then determine whether the coordinates of the key are within the specified coordinate range of the vehicle body.

[0143] It should be noted that the distance threshold d T It can adaptively change with changes in factors such as environment or distance, when |d1-d2|>d T When, that is, the difference is not at the distance threshold d T If the value is within the specified range, it is considered that there may be an incorrect location and the value is discarded; otherwise, the location result is considered acceptable.

[0144] S433: If the coordinates of the key are within the defined coordinate range of the vehicle body, then the key is determined to be inside the vehicle body; otherwise, the key is determined to be outside the vehicle body.

[0145] It should be noted that, in step S4, determining whether the key is inside the vehicle may further include the following steps:

[0146] S41': Based on the coordinates of the key in the two-dimensional coordinate system, calculate the arrival angle of the key relative to the master node, and mark it as the first angle θ′1; where,

[0147] S42': The master node collects the broadcast information of the quadrature and in-phase components sent by the key, and determines the arrival angle of the key relative to the master node through formulas 4 and 5, which is marked as the second angle θ2'.

[0148] S43': Determine whether the key is inside the vehicle body based on the first angle θ′1, the second angle θ′2, and the limited coordinate range of the vehicle body.

[0149] Specifically, the corresponding step S43' may include the following sub-steps:

[0150] S431': Determine whether the difference between the first angle θ′1 and the second angle θ′2 is within an acceptable angle threshold θ. T Within the range; wherein, the angle threshold θ T This is pre-set according to the test.

[0151] S432': When the difference is not within the angle threshold θ TIf the difference is within the specified range, repeat steps S2 to S4 to reposition the key. If the difference is within the specified angle threshold range, proceed to step S433 to determine whether the coordinates of the key are within the specified coordinate range of the vehicle body.

[0152] It should be noted that steps S41' to S43' and steps S41 to S43 can be parallel or complementary. When they are parallel, you can choose either steps S41' to S43' or steps S41 to S43, and only one of them needs to be performed. When they are complementary, steps S41' to S43' are performed after steps S41 to S43 are completed.

[0153] Specifically, in step S433, as Figure 8 As shown, the threshold value of the vehicle body boundary in the X-axis direction of the three-dimensional coordinate system is set to ε. χ Set the threshold value in the y-axis direction to ε. y Set the threshold value in the Z-axis direction to ε. z ( Figure 8 (Only the defined coordinate range in the XOY plane is shown; the defined coordinate range in the Z direction is not shown); the left boundary of the vehicle body in the X-axis direction is x L The right boundary is x H The left boundary of the vehicle body in the Y-axis direction is y. L The right boundary is y H The lower boundary of the vehicle body in the Z-axis direction is Z. L The upper boundary is Z. H When the coordinates (x) of the key p ,y p ,z p Satisfy: x L -ε x <x p <x H +ε x &&y L -ε y <y p <y H +ε y &&z L -ε z <z p <z H +ε Z If the key is located inside the vehicle, then it can be assumed that the key is inside the vehicle; if x satisfies: p <x L -ε x ||y p <y L -ε y ||x p >x H +ε x||y p >y H +ε y ||z p >z H +ε z ||z p >z H +ε z If the key is not in the vehicle body, the positioning process is repeated to reposition the key.

[0154] Specifically, in this embodiment, the phase difference and the angle of arrival of the key relative to the locator are calculated by formulas 4 and 5 according to the position information of the locator, the distance between the master node and the key and the angle of arrival of the key relative to the master node are calculated by formula 11 according to the received signal strength, whether the key is in the vehicle is determined according to the coordinate information of the key in step S4, and the data processing and calculation involved in this embodiment are all performed by the data processing module of the master node, thereby saving the power consumption of each locator and the key and prolonging the use time thereof.

[0155] In summary, the present application discloses a three-dimensional positioning method and device for an intelligent key of a vehicle. Four wireless communication modules of a tire pressure monitoring system arranged on the surfaces of four automobile wheel hubs serve as four locators, a receiver in the tire pressure monitoring system serves as a master node, the positions of the centers of the circles on which the four wheel hubs are located and the master node are known, and the positioning method comprises the following steps: determining whether the locators reach preset positions of the circles on which the wheel hubs are located, wherein the preset positions are at least one; when the locators reach each preset position of the circle on which the wheel hub is located, communicating with the key, measuring the angle of arrival of the key relative to the locator, and calculating the coordinates of the key in a horizontal two-dimensional coordinate system and a vertical two-dimensional coordinate system, respectively; obtaining the three-dimensional coordinates of the key according to the coordinates of the key in the horizontal two-dimensional coordinate system and the vertical two-dimensional coordinate system; determining whether the key is in the vehicle body; and when the key is not in the vehicle body, repeating the positioning process to reposition the key. The positioning method for the intelligent key of the vehicle can utilize the existing TPMS BLE system of the automobile, and on this basis, through the AOA seeking technology of BLE 5.1 and above and the BLE RSSI combined with the position information output by the magnetometer, the designed three-dimensional decomposition positioning algorithm is adopted to realize accurate positioning of the key. The present application can improve the positioning accuracy of the key, the accuracy of the in-vehicle and out-of-vehicle discrimination, simplify the key positioning system, reduce the calculation amount, and reduce the system cost.

[0156] In the above embodiments of the application, which have been described by way of example only, not by way of limitation, obvious modifications and alterations will occur to others upon reading and understanding the preceding descriptions. It is the purpose of the appended claims to cover all such modifications and alterations.

Claims

1. A method for three-dimensional positioning of a smart key of a vehicle, characterized in that, Four wireless communication modules of a tire pressure monitoring system arranged on four surfaces of four automobile wheel hubs respectively act as four locators, a receiver of the tire pressure monitoring system in the vehicle acts as a master node, a center of a circle on which the four wheel hubs are located and a position of the master node are known, and the positioning method comprises the following steps: According to arrival angles of the key relative to two preset positions of 0° and 90° of a preset angle in a horizontal direction of the surface on which the wheel hub is located, coordinates of the key in a horizontal two-dimensional coordinate system are determined, and according to arrival angles of the key relative to two preset positions of 180° and -90° of a preset angle in a vertical direction of the surface on which the wheel hub is located, coordinates of the key in a vertical two-dimensional coordinate system are determined; The four locators obtain four three-dimensional coordinates according to the coordinates of the key in the horizontal two-dimensional coordinate system and the vertical two-dimensional coordinate system, and obtain a three-dimensional coordinate of the key according to an average value of the four three-dimensional coordinates; wherein the horizontal two-dimensional coordinate system and the vertical two-dimensional coordinate system take the center of the circle on which the corresponding wheel hub is located as an origin; a distance or an angle between the master node and the key is calculated according to the position of the master node and the three-dimensional coordinate of the key, and whether the key is in the vehicle body is judged based on a distance threshold value and an angle threshold value respectively.

2. The positioning method according to claim 1, characterized in that, The positioning method further comprises judging whether the locator reaches the preset position of the circle on which the wheel hub is located, wherein the preset position is at least one.

3. The positioning method of claim 2, wherein: Whether the locator reaches the preset position of the circle on which the wheel hub is located is determined by measuring a magnetic field intensity by a magnetometer.

4. The positioning method according to claim 3, characterized in that, Whether the locator reaches the preset position comprises the following steps: A horizontal component and a vertical component of the magnetic field intensity are measured by the magnetometer; An included angle between the magnetic field intensity and a coordinate axis of the surface on which the wheel hub is located is calculated; Whether the included angle is equal to a preset angle is judged; When the included angle is equal to the preset angle, the locator reaches the preset position; when the included angle is not equal to the preset angle, the locator does not reach the preset position.

5. The positioning method of claim 1, wherein, Whether the key is in the vehicle body is judged by: According to the coordinates of the key in the three-dimensional coordinate system, a distance between the master node and the key is calculated, and is marked as a first distance; According to a received signal strength corresponding to the signal transmitted by the key and collected by the master node, a distance between the master node and the key is calculated, and is marked as a second distance; Whether the key is in the vehicle body is judged according to the first distance, the second distance and a limited coordinate range of the vehicle body.

6. The positioning method of claim 5, wherein: Whether the key is in the vehicle body is judged according to the first distance, the second distance and the limited coordinate range of the vehicle body, and specifically comprises the following steps: Whether a difference between the first distance and the second distance is within an acceptable distance threshold range is judged; When the difference is not within the distance threshold range, the position of the key is repositioned; When the difference is within the distance threshold range, whether the coordinates of the key are within the limited coordinate range of the vehicle body is judged; When the coordinates of the key are within the limited coordinate range, the key is judged to be in the vehicle body; otherwise, the key is judged to be outside the vehicle body.

7. The positioning method of claim 5, wherein: The second distance is calculated according to the following formula: wherein d2 is the second distance, d ref is a reference distance, RSSI ref is the signal strength corresponding to the key transmission signal collected by the master node at the reference distance, RSSI is the signal strength corresponding to the key transmission signal collected by the master node at the second distance, and a is a path loss exponent.

8. The positioning method of claim 1, wherein, The process of determining whether the key is in the vehicle body comprises: According to the coordinates of the key and the master node in a three-dimensional coordinate system, the arrival angle of the key relative to the master node is calculated, marked as a first angle; The arrival angle of the key relative to the master node is determined by using the master node to collect broadcast information of quadrature components and in-phase components sent by the key, marked as a second angle; According to the first angle, the second angle and the limited coordinate range of the vehicle body, it is determined whether the key is in the vehicle body.

9. The positioning method of claim 8, wherein: According to the first angle, the second angle and the limited coordinate range of the vehicle body, it is determined whether the key is in the vehicle body, specifically comprising the following steps: It is determined whether the difference between the first angle and the second angle is within an acceptable angle threshold range; When the difference is not within the angle threshold range, the position of the key is repositioned; When the difference is within the angle threshold range, it is determined whether the coordinates of the key are within the limited coordinate range of the vehicle body; When the coordinates of the key are within the limited coordinate range, it is determined that the key is in the vehicle body; otherwise, it is determined that the key is outside the vehicle body.

10. The positioning method of claim 1, wherein: The locator comprises an antenna array, and the measurement of the arrival angle comprises the following steps: The key sends broadcast of measurement information containing in-phase components and quadrature components to the locator; The locator samples the broadcast information of the in-phase components and the quadrature components by switching different antennas; According to the sampled broadcast information of the in-phase components and the quadrature components, the phase difference of the key to different antennas of the locator is calculated; According to the phase difference, the real-time arrival angle of the positioning point relative to the key is calculated.

11. The positioning method of claim 10, wherein, The phase difference of the key to different antennas of the locator is calculated by the following formula: wherein, denotes the phase difference, I1denotes the in-phase component received by a first antenna in the locator antenna array from the key transmission, I2denotes the in-phase component received by a second antenna in the locator antenna array from the key transmission, Q1denotes the quadrature component received by a first antenna in the locator antenna array from the key transmission, and Q2denotes the quadrature component received by a second antenna in the locator antenna array from the key transmission.

12. The positioning method of claim 10, wherein, According to the phase difference, the arrival angle of the key relative to the master node is calculated by the following formula: wherein θ denotes the angle of arrival, denotes the phase difference, d denotes the distance of the two antennas of the localizer, and λ denotes the wavelength of the electromagnetic field propagating the broadcast, wherein 13. A smart key three-dimensional positioning device of a vehicle, characterized by, Four wireless communication modules of a tire pressure monitoring system arranged on the surfaces of four automobile wheel hubs act as four locators, a receiver in the tire pressure monitoring system acts as a master node, the center of the circle of the four wheel hubs and the position of the master node are known, The locator and the master node each comprise a sending module and a receiving module, and the key comprises a sending module; wherein the sending module sends positioning information, and the receiving module receives the positioning information; The master node further comprises a data processing module, which determines the coordinates of the key in a horizontal two-dimensional coordinate system according to the arrival angles of the key relative to the two preset positions of the locator on the horizontal direction of the surface of the wheel hub, i.e. 0° and 90°, and determines the coordinates of the key in a vertical two-dimensional coordinate system according to the arrival angles of the key relative to the two preset positions of the locator on the vertical direction of the surface of the wheel hub, i.e. 180° and -90°. The four locators obtain four three-dimensional coordinates according to the coordinates of the key in a horizontal two-dimensional coordinate system and a vertical two-dimensional coordinate system, and obtain the three-dimensional coordinates of the key according to the average of the four three-dimensional coordinates; wherein the horizontal two-dimensional coordinate system and the vertical two-dimensional coordinate system take the center of the circle where the corresponding wheel hub is located as the origin; According to the position of the master node and the three-dimensional coordinates of the key, the distance or angle between the two is calculated, and whether the key is in the vehicle body is judged based on the distance threshold and the angle threshold respectively.

14. The positioning device of claim 13, wherein: The wireless communication module and the receiver include an antenna array.

15. The positioning device of claim 13, wherein: The locator further includes a magnetometer, and the data processing module judges whether the locator reaches the preset position by the magnetic field intensity measured by the magnetometer.

16. The positioning device of claim 15, wherein: The data processing module calculates the angle between the magnetic field intensity and the coordinate axis according to the horizontal component and the vertical component of the magnetic field intensity measured by the magnetometer, to judge whether the locator reaches the preset position.

17. The positioning device of claim 13, wherein: The data processing module calculates the distance between the master node and the key according to the coordinates of the key and the master node in the three-dimensional coordinate system, and marks it as the first distance, wherein the coordinates of the master node in the three-dimensional coordinate system are known; The data processing module calculates the distance between the master node and the key according to the signal strength sent by the key collected by the master node, and marks it as the second distance; The data processing module judges whether the key is in the vehicle body according to the first distance, the second distance and the limited coordinate range of the vehicle body.

18. The positioning device of claim 17, wherein: The data processing module calculates the second distance by the following formula: wherein d2 is the second distance, d ref is a reference distance, RSSI ref is a signal strength of the key transmission signal collected by the receiving module of the master node at the reference distance d ref RSSI is a signal strength of the key transmission signal corresponding to the second distance, and a is a path loss exponent.

19. The positioning device of claim 13, wherein: The data processing module calculates the arrival angle of the key relative to the master node according to the coordinates of the key and the master node in the three-dimensional coordinate system, and marks it as the first angle, wherein the coordinates of the master node in the three-dimensional coordinate system are known; The data processing module calculates the arrival angle of the key relative to the master node by using the broadcast information of the quadrature component and the in-phase component of the signal sent by the key collected by the master node, and marks it as the second angle; The data processing module judges whether the key is in the vehicle body according to the first angle, the second angle and the limited coordinate range of the vehicle body.

20. The positioning device of claim 13 or 19, wherein: The data processing module calculates the arrival angle by the following formula: wherein θ denotes the angle of arrival, denotes the phase difference of the electromagnetic wave transmitted by the transmitting module received by two of the antennas of the antenna array of the receiving module, d denotes the distance between the two antennas of the antenna array of the receiving module, and λ denotes the wavelength of the electromagnetic field transmitted by the transmitting module, wherein 21. The positioning device of claim 20, wherein: The data processing module calculates the phase difference of the electromagnetic wave sent by the sending module received by two antennas in the antenna array of the receiving module by the following formula: wherein, denotes the phase difference, I1 denotes the in-phase component transmitted by the transmitting module received by a first antenna of the antenna array of the receiving module, I2 denotes the in-phase component transmitted by the transmitting module received by a second antenna of the antenna array of the receiving module, Q1 denotes the quadrature component transmitted by the transmitting module received by a first antenna of the antenna array of the receiving module, and Q2 denotes the quadrature component transmitted by the transmitting module received by a second antenna of the antenna array of the receiving module.

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