Device and method for measuring azimuth angle of OBU

Abstract

The invention discloses a device and a method for measuring an azimuth angle of an OBU (On Board Unit). The device comprises an array antenna, a power divider group, a phase shifter group, a combiner group, a power detection circuit and an MCU (Microprogrammed Control Unit), the array antenna consists of a plurality of antenna units and is used for receiving microwave signals of the OBU; the power divider group is composed of a plurality of bisection power dividers, and each antenna unit is correspondingly connected with one bisection power divider; the phase shifter group consists of a plurality of phase shifters and is used for carrying out fixed phase delay on the output signal of the power divider; the combiner group consists of a plurality of combiners, is connected with the output ends of the power dividers, and is used for combining output signals of the power dividers; the power detection circuit is connected with the power dividers and the combiner and is used for detecting a signal power value processed by the power divider group and the combiner group; and the MCU is connected with the power detection circuit and is used for acquiring a result of the power detection circuit and outputting an OBU azimuth angle. The problems that a DOA positioning scheme is complex in hardware and structure and high in equipment cost are solved.

Description

Technical Field

[0001] The invention relates to the technical field of electronic toll collection (ETC), and in particular to a device and method for measuring an OBU azimuth. Background Art

[0002] In the ETC charging system, problems such as adjacent lane interference are generally solved by adding a positioning module to the RSU device. The positioning module uses technologies such as DOA to obtain the azimuth of the OBU, calculates the exact position of the OBU based on the azimuth, and uses the positioning results to distinguish between adjacent lane vehicles and vehicles on the own lane.

[0003] Prior art 1: Patent application number 201210008561.7 (DBF-based OBU positioning method, positioning device and system) provides an OBU positioning method and device based on DBF technology. The method adopts DBF (conventional DOA) technology, and multiple channels process the signals of the array antenna in parallel and synchronously, convert the microwave signal into an intermediate frequency signal and then perform digital down-conversion, calculate the autocorrelation matrix between all channels, obtain the azimuth of the OBU through a power spectrum estimation algorithm, and calculate the two-dimensional coordinates of the OBU from multiple azimuths.

[0004] Prior art 2: Patent application number 202310503388.6 (An OBU positioning device and positioning method based on dual receiving channels) provides an OBU positioning method with dual receiving channels. This method optimizes the conventional DOA technology, retains only two down-conversion receiving channels, and time-shares the optional antenna units of the array antenna. The autocorrelation matrix of the entire array antenna is restored through a fixed reference channel to achieve OBU positioning.

[0005] Prior art 3: Patent application No. 201410324090.X (A method and device for calculating the incident angle of an on-board unit OBU) provides a method for calculating the direction angle, which performs power division on the received signal of the antenna unit, synthesizes the signals of adjacent antennas, obtains the synthesized signal amplitude V2, and the signal amplitude before synthesis is V1, and calculates the phase difference of the adjacent antenna signals. The azimuth angle is calculated by the phase difference. Since the amplitude value cannot be negative, the final incident direction angle cannot distinguish between left and right, that is, this method cannot identify two symmetrical targets on the left and right of the array antenna normal.

[0006] Conventional and dual-receiving channel DOA technologies are both based on software radio synchronous down-conversion reception, using high-speed signal processors and power spectrum estimation algorithms to obtain the azimuth of the OBU, thereby completing precise positioning. The advantages of this solution are high positioning accuracy, good hardware versatility, and many mature algorithms available. However, the disadvantage is that both methods cannot bypass synchronous down-conversion and algorithm processing, and the hardware and structure are relatively complex, the cost is high, and the performance requirements of the processor are high. They are not suitable for occasions that do not require high positioning accuracy but are very sensitive to equipment costs, such as ETC parking lots. Summary of the invention

[0007] In view of the above technical problems, the present invention provides a device and method for measuring the azimuth of an OBU, the method comprising:

[0008] Including: array antenna, power divider group, phase shifter group, combiner group, power detection circuit, MCU;

[0009] The array antenna is composed of multiple antenna units, which are arranged in a straight line. The array antenna is used to receive microwave signals from the OBU, and the spacing between the antenna units is half of the OBU microwave signal.

[0010] A power divider group, composed of a plurality of bisection power dividers, each antenna unit is connected to a corresponding bisection power divider; each bisection power divider receives a microwave signal from the antenna unit and divides the microwave signal into two equal-power and equal-phase signals;

[0011] A phase shifter group, composed of a plurality of phase shifters, is connected to the output end of some power dividers to delay the output signal of the power divider with a fixed phase; and then sends the output signal to the connected power divider;

[0012] A combiner group, composed of a plurality of combiners, connected to the output end of the power divider, and used for combining the output signals of the power divider;

[0013] A power detection circuit is connected to the power divider and the combiner, and is used to detect the power value of the signal after being processed by the power divider group and the combiner group;

[0014] The MCU is connected to the power detection circuit and is used to obtain the result of the power detection circuit and output the OBU azimuth.

[0015] Furthermore, the array antenna is composed of a plurality of antenna units, specifically including: four antenna units, namely antenna (1), antenna (2), antenna (3), and antenna 4, and the received microwave signals are S1, S2, S3, and S4 respectively; the spacing between antenna (1) and antenna (2), and between antenna (3) and antenna 4 is d, and the spacing between antenna (2) and antenna (3) is d1, and when d=d1, the four antenna units form a one-dimensional uniform linear array.

[0016] Furthermore, the power divider group is composed of a plurality of two-equal power dividers, each antenna unit is connected to a corresponding two-equal power divider, specifically including: 8 independent two-equal power dividers, among which power divider (11), power divider (21), power divider (31), and power divider (41) are used to divide the signals received by the four antenna units into two equal-power and equal-phase signals, respectively, to obtain eight signals S11, S12, S21, S22, S31, S32, S41, and S42.

[0017] Furthermore, a phase shifter group, composed of a plurality of phase shifters, is connected to the output end of a part of the power divider to delay the output signal of the power divider with a fixed phase, including:

[0018] Phase shifter (1) and phase shifter (2) respectively delay S22 and S32 by a fixed phase time φ Δ After phase delay, signals S22D and S32D are obtained.

[0019] Furthermore, a combiner group, composed of a plurality of combiners, is connected to the output end of the power divider and is used to combine the output signals of the power divider, including:

[0020] Combiner group, consisting of a 4-output combiner and two 2-input combiners;

[0021] The 4-input combiner is used to combine the four signals S11, S21, S31, and S41 to obtain a new signal S0, and the power of S0 is P0.

[0022] Furthermore, it also includes:

[0023] The power divider (12), the power divider (22), the power divider (32) and the power divider (42) are used to respectively divide the S12, S22D, S32D and S42 signals into two equal-power and equal-phase signals to obtain eight signals S121, S122, S221, S222, S321, S322, S421 and S422, wherein the powers of S121, S221, S321 and S421 are P1, P2, P3 and P4 respectively.

[0024] Furthermore, it also includes:

[0025] The combiner (12) and the combiner (34) respectively perform power addition on S122, S222, S322 and S422 to combine them into signals S12 and S34, and the corresponding powers are P12 and P34 respectively.

[0026] Furthermore, the power detection circuit is used to detect the power value of the signal after being processed by the power divider group and the combiner group, including:

[0027] The power detection circuit is used to detect the power values ​​of P1, P2, P3, P4, P0, P12, and P34, and transmit the detected power values ​​to the MCU.

[0028] Furthermore, it also includes:

[0029] Communication interface, used to communicate with other modules and controllers of RSU, and output azimuth and positioning results.

[0030] Furthermore, it also includes:

[0031] The memory is used to store the power coefficient and the corresponding incident azimuth angle.

[0032] A method for testing and measuring an OBU azimuth, comprising:

[0033] Determine the theoretical power coefficient curve corresponding to the phase angle according to the spacing between antenna units and the phase delay value of the phase shifter;

[0034] When a vehicle passes through the gate, the multiple power values ​​passing through the combiner and power splitter are detected according to the OBU signal received by the positioning module;

[0035] According to the multiple power values, calculate the power coefficient corresponding to the OBU;

[0036] The OBU azimuth is determined according to the power coefficient and the theoretical power coefficient curve.

[0037] Furthermore, according to the spacing between the antenna units and the phase delay value of the phase shifter, a theoretical power coefficient curve corresponding to the phase angle is determined, including:

[0038] According to the spacing d, d1 of the antenna units and the phase delay value of the phase shifter Calculate the theoretical power coefficient K1, K2 curves within the phase angle θ∈[0,180] range, and save the theoretical power coefficient into the power coefficient table.

[0039] Furthermore, multiple power values ​​passing through the combiner and the power divider are detected, including:

[0040] Power values ​​P1, P2, P3, P4, P0, P12, P34.

[0041] Further, according to the multiple power values, the power coefficient corresponding to the OBU is calculated, including:

[0042] Calculate the average power Pa, Pa = (P1 + P2 + P3 + P4) / 4;

[0043] Calculate the power coefficient corresponding to the OBU, K1 = P0 / Pa, K2 = (P12-P34) / Pa.

[0044] Further, according to the power coefficient and the theoretical power coefficient curve, the OBU azimuth is determined, including:

[0045] According to the values ​​of power coefficients K1 and K2, find the corresponding azimuth angle θ from the power coefficient table;

[0046] Take the azimuths of the two directions to calculate the coordinates of the OBU and output them.

[0047] The present invention provides a device and method for measuring the azimuth of an OBU. The device uses the relationship between the amplitude and phase of a microwave signal to detect the power of multiple signals, converts the power into a power coefficient, and then finds the azimuth corresponding to the power coefficient through a lookup table method, thereby realizing OBU positioning. The azimuth measurement process does not have a complex algorithm and does not require high processor performance. The power divider, phase shifter, and combiner, which are mainly composed of the power divider, phase shifter, and combiner, are all realized with PCB microstrip lines, which are relatively low in cost. The invention aims to solve the problems of complex hardware and structure and high equipment cost of conventional DOA positioning solutions, and fill the ETC charging scenario with low positioning accuracy requirements and a relatively simple application environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a block diagram of a device for measuring an OBU azimuth provided by an embodiment of the present invention;

[0049] Figure 2 It is a circuit diagram of a device for measuring an OBU azimuth provided by an embodiment of the present invention;

[0050] Figure 3 It is a schematic flow chart of a method for testing an OBU azimuth provided by an embodiment of the present invention;

[0051] Figure 4 It is a curve of the relationship between power coefficient and azimuth angle provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0052] Many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present invention, so the present invention is not limited to the specific implementation disclosed below.

[0053] The present invention proposes a device for measuring the azimuth of an OBU, comprising: an array antenna, a power divider group, a phase shifter group, a combiner group, a power detection circuit, an MCU, a storage chip, and a communication interface; the device block diagram is as follows Figure 1 As shown,

[0054] The array antenna is composed of multiple antenna units, which are arranged in a straight line. The array antenna is used to receive microwave signals from the OBU, and the spacing between the antenna units is half of the OBU microwave signal.

[0055] A power divider group, composed of a plurality of bisection power dividers, each antenna unit is connected to a corresponding bisection power divider; each bisection power divider receives a microwave signal from the antenna unit and divides the microwave signal into two equal-power and equal-phase signals;

[0056] A phase shifter group, composed of a plurality of phase shifters, is connected to the output end of some power dividers to delay the output signal of the power divider with a fixed phase; and then sends the output signal to the connected power divider;

[0057] A combiner group, composed of a plurality of combiners, connected to the output end of the power divider, and used for combining the output signals of the power divider;

[0058] A power detection circuit is connected to the power divider and the combiner, and is used to detect the power value of the signal after being processed by the power divider group and the combiner group;

[0059] The MCU is connected to the power detection circuit and is used to obtain the result of the power detection circuit and output the OBU azimuth.

[0060] Figure 2 In the figure, the OBU transmits a signal to the array antenna from the angle θ. Since the distance from the OBU to the array antenna is much larger than the distance between the antenna units, it can be considered that the signal is incident on each antenna unit in parallel, that is, the direction angles of all antenna units are the same.

[0061] The array antenna is composed of a plurality of antenna units, specifically comprising: four antenna units, namely antenna (1), antenna (2), antenna (3), and antenna 4, and the received microwave signals are S1, S2, S3, and S4 respectively; the spacing between antenna (1) and antenna (2), and between antenna (3) and antenna 4 is d, and the spacing between antenna (2) and antenna (3) is d1. When d=d1, the four antenna units form a one-dimensional uniform linear array, and the spacing between the four antenna units is approximately half of the wavelength of the OBU microwave signal, that is, about 26 mm.

[0062] The power divider group is composed of a plurality of two-equal power dividers, each antenna unit is connected to a corresponding two-equal power divider, and specifically includes: 8 independent two-equal power dividers, wherein the power divider (11), the power divider (21), the power divider (31), and the power divider (41) are used to divide the signals received by the four antenna units into two equal-power and equal-phase signals, respectively, to obtain eight signals S11, S12, S21, S22, S31, S32, S41, and S42.

[0063] Phase shifter (1) and phase shifter (2) respectively delay S22 and S32 by a fixed phase time φ Δ After phase delay, signals S22D and S32D are obtained.

[0064] Combiner group, consisting of a 4-output combiner and two 2-input combiners;

[0065] The 4-input combiner is used to combine the four signals S11, S21, S31, and S41 to obtain a new signal S0, and the power of S0 is P0.

[0066] The power divider (12), the power divider (22), the power divider (32) and the power divider (42) are used to respectively divide the S12, S22D, S32D and S42 signals into two equal-power and equal-phase signals to obtain eight signals S121, S122, S221, S222, S321, S322, S421 and S422, wherein the powers of S121, S221, S321 and S421 are P1, P2, P3 and P4 respectively.

[0067] The combiner (12) and the combiner (34) respectively perform power addition on S122, S222, S322 and S422 to combine them into signals S12 and S34, and the corresponding powers are P12 and P34 respectively.

[0068] The power detection circuit is used to detect the power values ​​of P1, P2, P3, P4, P0, P12, and P34, and transmit the detected power values ​​to the MCU.

[0069] Communication interface, used to communicate with other modules and controllers of RSU, and output azimuth and positioning results.

[0070] The memory is used to store the power coefficient and the corresponding incident azimuth angle.

[0071] The present invention also provides a method for testing the OBU azimuth, such as Figure 3 As shown. It includes the following steps:

[0072] Determine the theoretical power coefficient curve corresponding to the phase angle according to the spacing between antenna units and the phase delay value of the phase shifter;

[0073] When a vehicle passes through the gate, the multiple power values ​​passing through the combiner and power splitter are detected according to the OBU signal received by the positioning module;

[0074] According to the multiple power values, calculate the power coefficient corresponding to the OBU;

[0075] The OBU azimuth is determined according to the power coefficient and the theoretical power coefficient curve.

[0076] Furthermore, according to the spacing between the antenna units and the phase delay value of the phase shifter, a theoretical power coefficient curve corresponding to the phase angle is determined, including:

[0077] According to the spacing d, d1 of the antenna units and the phase delay value of the phase shifter Calculate the theoretical power coefficient K1, K2 curves within the phase angle θ∈[0,180] range, and save the theoretical power coefficient into the power coefficient table.

[0078] Furthermore, multiple power values ​​passing through the combiner and the power divider are detected, including:

[0079] Power values ​​P1, P2, P3, P4, P0, P12, P34.

[0080] Further, according to the multiple power values, the power coefficient corresponding to the OBU is calculated, including:

[0081] Calculate the average power Pa, Pa = (P1 + P2 + P3 + P4) / 4;

[0082] Calculate the power coefficient corresponding to the OBU, K1 = P0 / Pa, K2 = (P12-P34) / Pa.

[0083] Further, according to the power coefficient and the theoretical power coefficient curve, the OBU azimuth is determined, including:

[0084] According to the values ​​of power coefficients K1 and K2, find the corresponding azimuth angle θ from the power coefficient table;

[0085] Take the azimuths of the two directions to calculate the coordinates of the OBU and output them.

[0086] The principle of calculating the azimuth angle through the power value is as follows: Since the distance between the antenna units is very close, the distance from the OBU to the antenna is much greater than the distance between the antenna units, so the signal power received by the antenna units is equal, and the phase difference is only related to the OBU incident azimuth angle θ. The OBU transmits a microwave signal from the θ direction, and the signal wavelength is λ. If the power received by each antenna unit is P, the power obtained after passing through the power divider, phase shifter, and combiner in the figure satisfies the following relationship:

[0087]

[0088]

[0089]

[0090]

[0091] Let K1 and K2 be power coefficients, and K1 = P0 / P1, K2 = (P12-P34) / P1, then we have

[0092]

[0093]

[0094] When d=d1=λ / 2, When K1, K2 and θ are related as follows:

[0095]

[0096] K2=2sin(πcosθ)

[0097] That is, when the array antenna is a one-dimensional uniform linear array, the spacing is λ / 2, and the phase shifter delay is 90°, the corresponding relationship curve between the power coefficient and the incident azimuth angle is shown in Figure 4.

[0098] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0099] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0100] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0101] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalents that do not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A device for measuring the azimuth of an OBU, characterized in that: include: Array antenna, power divider group, phase shifter group, combiner group, power detection circuit, MCU; An array antenna consists of multiple antenna units that are arranged in a straight line. The array antenna is used to receive the microwave signal of the OBU, and the spacing between antenna units is half of the microwave signal of the OBU; A power divider group, composed of a plurality of bisection power dividers, each antenna unit is connected to a corresponding bisection power divider; each bisection power divider receives a microwave signal from the antenna unit and divides the microwave signal into two equal-power and equal-phase signals; A phase shifter group, composed of a plurality of phase shifters, is connected to the output end of some power dividers to delay the output signal of the power divider with a fixed phase; The output signal is then sent to the connected power splitter; A combiner group, composed of a plurality of combiners, connected to the output end of the power divider, and used for combining the output signals of the power divider; A power detection circuit is connected to the power divider and the combiner, and is used to detect the power value of the signal after being processed by the power divider group and the combiner group; The MCU is connected to the power detection circuit and is used to obtain the result of the power detection circuit and output the OBU azimuth.

2. The device according to claim 1, characterized in that The array antenna is composed of a plurality of antenna units, specifically comprising: four antenna units, namely antenna (1), antenna (2), antenna (3), and antenna 4, and the received microwave signals are S1, S2, S3, and S4 respectively; the spacing between antenna (1) and antenna (2), and between antenna (3) and antenna 4 is d, and the spacing between antenna (2) and antenna (3) is d1, and when d=d1, the four antenna units form a one-dimensional uniform linear array.

3. The device according to claim 1, characterized in that The power divider group is composed of a plurality of two-equal power dividers, each antenna unit is connected to a corresponding two-equal power divider, and specifically includes: 8 independent two-equal power dividers, wherein the power divider (11), the power divider (21), the power divider (31), and the power divider (41) are used to divide the signals received by the four antenna units into two equal-power and equal-phase signals, respectively, to obtain eight signals S11, S12, S21, S22, S31, S32, S41, and S42.

4. The device according to claim 1, characterized in that The phase shifter group, which is composed of a plurality of phase shifters, is connected to the output end of some power dividers to delay the output signal of the power divider with a fixed phase, including: Phase shifter (1) and phase shifter (2) respectively delay S22 and S32 by a fixed phase. After phase delay, signals S22D and S32D are obtained.

5. The device according to claim 1, characterized in that The combiner group, which is composed of multiple combiners and connected to the output end of the power divider, is used to combine the output signals of the power divider, including: Combiner group, consisting of a 4-output combiner and two 2-input combiners; The 4-input combiner is used to combine the four signals S11, S21, S31, and S41 to obtain a new signal S0, and the power of S0 is P0.

6. The device according to claim 1, characterized in that Also includes: The power divider (12), the power divider (22), the power divider (32) and the power divider (42) are used to respectively divide the S12, S22D, S32D and S42 signals into two equal-power and equal-phase signals to obtain eight signals S121, S122, S221, S222, S321, S322, S421 and S422, wherein the powers of S121, S221, S321 and S421 are P1, P2, P3 and P4 respectively.

7. The device according to claim 1, characterized in that Also includes: The combiner (12) and the combiner (34) respectively perform power addition on S122, S222, S322 and S422 to combine them into signals S12 and S34, and the corresponding powers are P12 and P34 respectively.

8. The device according to claim 1, characterized in that The power detection circuit is used to detect the signal power value after being processed by the power divider group and the combiner group, including: The power detection circuit is used to detect the power values ​​of P1, P2, P3, P4, P0, P12, and P34, and transmit the detected power values ​​to the MCU.

9. The device according to claim 1, characterized in that Also includes: Communication interface, used to communicate with other modules and controllers of RSU, and output azimuth and positioning results.

10. The device according to claim 1, characterized in that Also includes: The memory is used to store the power coefficient and the corresponding incident azimuth angle.

11. A method for measuring the azimuth of an OBU using the device according to any one of claims 1 to 10, characterized in that: include: Determine the theoretical power coefficient curve corresponding to the phase angle according to the spacing between antenna units and the phase delay value of the phase shifter; When a vehicle passes through the gate, the multiple power values ​​passing through the combiner and power splitter are detected according to the OBU signal received by the positioning module; According to the multiple power values, calculate the power coefficient corresponding to the OBU; The OBU azimuth is determined according to the power coefficient and the theoretical power coefficient curve.

12. The method according to claim 11, characterized in that According to the spacing of the antenna units and the phase delay value of the phase shifter, the theoretical power coefficient curve corresponding to the phase angle is determined, including: According to the spacing d, d1 of the antenna units and the phase delay value of the phase shifter Calculate the theoretical power coefficient K1, K2 curves within the phase angle θ∈[0,180] range, and save the theoretical power coefficient into the power coefficient table.

13. The method according to claim 11, characterized in that Detect multiple power levels through combiners and splitters, including: Power values ​​P1, P2, P3, P4, P0, P12, P34.

14. The method according to claim 11, characterized in that Calculating the power coefficient corresponding to the OBU according to the multiple power values ​​includes: Calculate the average power Pa, Pa = (P1 + P2 + P3 + P4) / 4; Calculate the power coefficient corresponding to the OBU, K1 = P0 / Pa, K2 = (P12-P34) / Pa.

15. The method according to claim 11, characterized in that According to the power coefficient and the theoretical power coefficient curve, the OBU azimuth is determined, including: According to the values ​​of power coefficients K1 and K2, find the corresponding azimuth angle θ from the power coefficient table; Take the azimuths in two directions to calculate the coordinates of the OBU and output them.

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