Positioning device and clock correction method

Abstract

Provided are a positioning device and a clock correcting method capable of accurately correcting phases between clocks of radio communication devices.　This positioning device for measuring the position of a mobile communication unit comprises: a first radio communication unit; a second radio communication unit disposed in a position a known first prescribed distance from the first radio communication unit; a distance calculating unit for obtaining a distance between the first radio communication unit and the second radio communication unit on the basis of a phase when the second radio communication unit receives a signal having a first frequency transmitted from the first radio communication unit, a phase when the second radio communication unit receives a signal having a second frequency transmitted from the first radio communication unit, and the first prescribed distance; and a synchronization adjusting unit for synchronizing the first radio communication unit and the second radio communication unit from a difference between the distance calculated by the distance calculating unit and the first prescribed distance.

Description

[Technical field]

[0001] The present disclosure relates to a positioning device and a clock correction method. [Background technology]

[0002] Conventionally, there is a time synchronization system including a parent device that supplies a synchronization signal for synchronizing radio base stations, and a child device that is connected to the parent device via a transmission path having a first channel and a second channel. The child device includes a GPS receiver that receives a reference signal of a Global Positioning System (GPS), a multiplexer that multiplexes the reference signal onto a first channel of an uplink signal to the parent device, and a transmitter that transmits the uplink signal via the transmission path. The parent device includes a multiplexer that multiplexes a delay measurement signal onto a second channel of a downlink signal to the child device, a transmitter that transmits the downlink signal via the transmission path, a separator that separates the first channel and the second channel from the uplink signal from the child device, a delay measurement unit that measures a delay time of the transmission path based on the delay measurement signal of the second channel, a first phase correction unit that corrects the phase of a reference signal of the first channel based on the delay time, and an output unit that outputs the first synchronization signal based on the reference signal corrected by the first phase correction unit (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-004834 A Summary of the Invention [Problem to be solved by the invention]

[0004] Since GPS signals are easily affected by the communication environment, such as multipath reflections, there is a limit to the accuracy of correction when using GPS signals to correct the phase of the GPS reference signal.

[0005] Incidentally, when positioning is performed between wireless communication devices using Time Of Arrival (TOA) and Round Trip Time (RTT) is measured, the clock phase between the wireless communication devices requires accuracy of the order of 1 ns (nanosecond).

[0006] It is therefore an object of the present invention to provide a positioning device and a clock correction method that are capable of correcting the phases of the clocks of wireless communication devices with high accuracy. [Means for solving the problem]

[0007] A positioning device of an embodiment of the present disclosure is a positioning device that positions a position of a mobile communication unit, and includes a first wireless communication unit, a second wireless communication unit arranged at a position a known first predetermined distance from the first wireless communication unit, a distance calculation unit that calculates a distance between the first wireless communication unit and the second wireless communication unit based on the phase when the second wireless communication unit receives a signal of a first frequency transmitted from the first wireless communication unit, the phase when the second wireless communication unit receives a signal of a second frequency transmitted from the first wireless communication unit, and the first predetermined distance, and a synchronization adjustment unit that synchronizes the first wireless communication unit and the second wireless communication unit based on the difference between the distance calculated by the distance calculation unit and the first predetermined distance. Effect of the Invention

[0008] It is possible to provide a positioning device and a clock correction method capable of correcting the phases of the clocks of wireless communication devices with high accuracy. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram showing a vehicle 10 equipped with a positioning device according to an embodiment. [Diagram 2] 1 is a block diagram showing the configurations of a vehicle 10 equipped with a positioning device 100 according to an embodiment and a smartphone 200. FIG. [Diagram 3] FIG. 1 is a diagram showing two hyperbolas that satisfy equation (7). [Figure 4]FIG. 13 is a diagram showing two hyperbolas that satisfy the formula (7) and the coverage areas of wireless communication units 110A and 110B. [Diagram 5] FIG. 13 is a diagram showing four hyperbolas obtained by the third positioning method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment to which the positioning device and clock correction method of the present disclosure are applied will be described.

[0011] <Embodiment> FIG. 1 is a diagram showing a vehicle 10 equipped with a positioning device according to an embodiment. FIG. 1 shows an XY coordinate system with the origin O set to the center of the vehicle 10 in a plan view. A plurality of wireless communication units 110 are arranged at the four corners of the body of the vehicle 10. The wireless communication units 110 are an example of a wireless communication device. FIG. 1 shows ten wireless communication units 110 as an example. One wireless communication unit 110 is provided at each of the left and right ends of the front of the vehicle 10, and one wireless communication unit 110 is provided at each of the left and right ends of the rear of the vehicle 10. In addition, one wireless communication unit 110 is provided at each of the front and rear ends of the left side of the vehicle 10 and the center in the front-rear direction, and one wireless communication unit 110 is provided at each of the front and rear ends of the right side of the vehicle 10 and the center in the front-rear direction.

[0012] Any one of the ten wireless communication units 110 is an example of a first wireless communication unit, any other one is an example of a second wireless communication unit, and any other one is an example of a third wireless communication unit.

[0013] Here, as an example, the wireless communication unit 110 provided at the front end on the right side of the vehicle 10 is distinguished as wireless communication unit 110A, the wireless communication unit 110 provided at the rear end on the right side of the vehicle 10 is distinguished as wireless communication unit 110B, and the wireless communication unit 110 provided in the center in the front-to-rear direction on the right side of the vehicle 10 is distinguished as wireless communication unit 110C. The wireless communication unit 110A is an example of a first wireless communication unit, the wireless communication unit 110B is an example of a second wireless communication unit, and the wireless communication unit 110C is an example of a third wireless communication unit.

[0014] The ten wireless communication units 110 all use the same clock frequency for their operation. Each wireless communication unit 110 is a wireless communication unit for transmitting or receiving data to or from the smartphone 200, and is, for example, a short-range wireless communication device conforming to the Bluetooth (registered trademark) standard. Each wireless communication unit 110 has multiple antennas. Note that, although a form in which the wireless communication unit 110 is a short-range wireless communication device conforming to the Bluetooth standard will be described here, the wireless communication unit 110 may be a device that performs communication conforming to a WLAN (Wireless Local Area Network) or other standards.

[0015] 2 is a block diagram showing the configuration of a vehicle 10 equipped with a positioning device 100 according to an embodiment, and a smartphone 200. The positioning device 100 includes ten wireless communication units 110 mounted on the vehicle 10, and an ECU (Electronic Control Unit) 120 mounted on the vehicle 10. Each wireless communication unit 110 has a plurality of antennas 111. The number of antennas 111 connected to each wireless communication unit 110 may be two or more, and may be about three.

[0016] The smartphone 200 is an example of a mobile communication unit, and its position is determined (located) by the positioning device 100 when it is outside the vehicle 10. The smartphone 200 has a control unit 210 and a communication unit 220. Through the smartphone 200, the user can perform operations such as unlocking / locking the remote key of the vehicle 10 and operating automatic parking assistance.

[0017] The wireless communication unit 110 includes, for example, a power amplifier (PA), a low noise amplifier (LNA), an orthogonal modulator (OM), an orthogonal demodulator (ODM), a voltage controlled oscillator (VCO), a phase locked loop (PLL), and a codec processing unit. The PA is connected to an antenna 111. The wireless communication unit 110 is controlled by an ECU 120 and communicates by Bluetooth packet signals for distance measurement.

[0018] The ECU 120 is an ECU for the positioning device 100. In addition to the ECU 120, various ECUs are mounted on the vehicle 10, and are communicatively connected to the ECU 120 via an in-vehicle network.

[0019] The ECU 120 is realized by a computer including a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and an internal bus. The ECU 120 has a main control unit 121, a distance calculation unit 122, a synchronization control unit 123, a distance difference calculation unit 124, a direction derivation unit 125, a positioning unit 126, and a memory 127. The main control unit 121, the distance calculation unit 122, the synchronization control unit 123, the distance difference calculation unit 124, the direction derivation unit 125, and the positioning unit 126 are functional blocks showing the functions of the programs executed by the ECU 120. The memory 127 is a functional representation of the memory of the ECU 120.

[0020] The following describes the first to fourth positioning methods that can be executed by ECU 120. In any of the first to fourth positioning methods, main control unit 121 is a processing unit that supervises control processing of ECU 120, and executes processing other than the processing executed by distance calculation unit 122, synchronization control unit 123, distance difference calculation unit 124, direction derivation unit 125, and positioning unit 126.

[0021] Furthermore, memory 127 stores programs, data, etc. required for main control unit 121, distance calculation unit 122, synchronization control unit 123, distance difference calculation unit 124, direction derivation unit 125, and positioning unit 126 to execute the processes described above.

[0022] In addition, in any of the first to fourth positioning methods, ECU 120 performs synchronization processing. Therefore, the synchronization processing will be described first, and then the first to fourth positioning methods will be described. In the description of the first to fourth positioning methods, distance calculation unit 122, synchronization control unit 123, distance difference calculation unit 124, direction derivation unit 125, and positioning unit 126 will be described.

[0023] <Synchronization process> The synchronization process is a process performed by the synchronization control unit 123 based on the distance calculated by the distance calculation unit 122, and corrects the clocks of the wireless communication units 110A and 110B so that they are synchronized. The clock correction is achieved by the clock correction method of the embodiment. The clocks of the wireless communication units 110A and 110B are clocks used by the wireless communication units 110A and 110B for operation. The wireless communication units 110A and 110B communicate by Bluetooth packet signals. In the synchronization process, any one of the multiple antennas 111 connected to each wireless communication unit 110 may be used as the reference antenna 111.

[0024] The distance calculation unit 122 calculates the phase when the wireless communication unit 110B receives a packet signal of frequency f1 transmitted from the wireless communication unit 110A and the phase when the wireless communication unit 110B receives a packet signal of frequency f2 transmitted from the wireless communication unit 110A. And Based on this, the distance L between the wireless communication units 110A and 110B is calculated. Here, frequency f1 is an example of a first frequency, and frequency f2 is an example of a second frequency. The frequencies f1 and f2 are any two of a plurality of channels included in the Bluetooth communication band, and are frequencies at which the wave numbers between the wireless communication units 110A and 110B are the same. The predetermined distance L0 is an example of a first predetermined distance, and is the distance between the wireless communication units 110A and 110B. Since the wireless communication units 110A and 110B are attached to the front and rear end portions of the sides of the vehicle 10, the predetermined distance L0 is known.

[0025] More specifically, distance calculation unit 122 calculates distance L between wireless communication unit 110A and wireless communication unit 110B as follows. To calculate distance L, distance calculation unit 122 causes wireless communication unit 110A to transmit a packet signal of frequency f1 and a packet signal of frequency f2. The packet signals of frequencies f1 and f2 are received by wireless communication unit 110B. Data representing the predetermined distance L0 is stored in memory 127.

[0026] Here, if the wave number of the packet signal of frequency f1 between wireless communication units 110A and 110B and the wave number of the packet signal of frequency f2 between wireless communication units 110A and 110B are n, the phase when wireless communication unit 110B receives the packet signal of frequency f1 is P1, the phase when wireless communication unit 110B receives the packet signal of the second frequency is P2, the wavelength of the packet signal of frequency f1 is λ1, and the wavelength of the packet signal of frequency f2 is λ2, then distance calculation unit 122 can calculate distance L between wireless communication units 110A and 110B according to the following equations (1A) to (1E).

[0027] Specifically, when the wave number n, phase P1, and wavelength λ1 for a packet signal of frequency f1 are used, the distance L can be expressed by the following equation (1).

[0028]

number

[0029] Similarly, using the wave number n, phase P2, and wavelength λ2 for the packet signal of frequency f2, the distance L can be expressed by the following equation (2).

[0030]

number

[0031] From equation (1), the following equation (3) is obtained.

[0032]

number

[0033] Similarly, the following equation (4) can be obtained from equation (2).

[0034]

number

[0035] By eliminating the wave number n from equations (3) and (4) and rearranging them as shown below, the distance L can be expressed by the following equation (5). Here, c is the speed of light (3×10 8 m / sec).

[0036]

number

[0037] The synchronization control unit 123 corrects the clocks of the wireless communication units 110A and 110B so that they are synchronized based on the difference (L-L0) between the distance L calculated by the distance calculation unit 122 and the predetermined distance L0. If the clocks of the wireless communication units 110A and 110B are out of sync, the phases P1 and P2 become large, and the difference (L-L0) between the distance L calculated by equation (5) and the predetermined distance L0, which is a known distance, becomes large. The synchronization control unit 123 may correct the phase of the clock of at least one of the wireless communication units 110A and 110B based on the difference (L-L0) in distance so that the clocks of the wireless communication units 110A and 110B are synchronized. The synchronization control unit 123 can correct the phase of the clock with an accuracy of 1 ns (nanosecond). For example, if 360 degrees is analyzed at 1 MHz with a resolution of 10 bits, the phase can be analyzed at a level of 1 ns, and can be corrected with an accuracy of 1 ns.

[0038] Also, for example, the relationship between the difference in distance (L-L0) and the amount of correction for the phase of the clocks of the wireless communication units 110A and 110B can be measured in advance, table-format data can be created and stored in memory 127, and the amount of phase correction corresponding to the difference in distance (L-L0) can be read out to correct the phase of the clock of one of the wireless communication units 110A and 110B.

[0039] Note that, as an example, a case has been described here in which the distance calculation unit 122 causes the wireless communication unit 110A to transmit packet signals of frequencies f1 and f2, which are received by the wireless communication unit 110B, but conversely, the distance calculation unit 122 causes the wireless communication unit 110B to transmit packet signals of frequencies f1 and f2, which are received by the wireless communication unit 110A, whereby the phases of the clocks of the wireless communication units 110A and 110B can be corrected based on the packet signal transmitted from the wireless communication unit 110B. In this way, by transmitting and receiving packet signals in both directions between the wireless communication units 110A and 110B and performing synchronization processing, it is possible to perform phase correction with higher accuracy so that the phases of the clocks of the wireless communication units 110A and 110B match.

[0040] <First positioning method> When the clock has been corrected by the synchronization control unit 123, the distance difference calculation unit 124 calculates the distance difference between the distance L1 between the smartphone 200 and the wireless communication unit 110A and the distance L2 between the smartphone 200 and the wireless communication unit 110B based on the phase α1 when the wireless communication unit 110A receives a packet signal of frequency f1 transmitted from the smartphone 200, the phase α2 when the wireless communication unit 110A receives a packet signal of frequency f2 transmitted from the smartphone 200, the phase α3 when the wireless communication unit 110B receives the signal of frequency f1 transmitted from the smartphone 200, and the phase α4 when the wireless communication unit 110B receives the signal of frequency f2 transmitted from the smartphone 200.

[0041] Here, the packet signal of frequency f1 transmitted from the smartphone 200 is an example of a first signal, and the phase α1 when the wireless communication unit 110A receives the signal is an example of a first phase. The packet signal of frequency f2 transmitted from the smartphone 200 is an example of a second signal, and the phase α2 when the wireless communication unit 110A receives the signal is an example of a second phase. The phase α3 when the wireless communication unit 110B receives the signal of frequency f1 transmitted from the smartphone 200 is an example of a third phase. The phase α4 when the wireless communication unit 110B receives the signal of frequency f2 transmitted from the smartphone 200 is an example of a fourth phase. In the first positioning method, any one of the multiple antennas 111 connected to each wireless communication unit 110 may be used as the reference antenna 111. The multiple antennas 111 are used in a second positioning method described later, but when the positioning device 100 does not perform the second positioning method, each wireless communication unit 110 may have only one antenna 111.

[0042] The absolute value of the distance difference between the distance L1 and the distance L2, |L1-L2|, can be expressed as in the following equation (6).

[0043]

number

[0044] The distance difference calculation unit 124 calculates the absolute value |L1-L2| as in the following equation (7) by eliminating the wave number n from equation (6), where c is the speed of light.

[0045]

number

[0046] When the distance difference calculation unit 124 calculates the distance difference (|L1-L2|) between distance L1 and distance L2 in this manner, the positioning unit 126 calculates the position of the smartphone 200 relative to the wireless communication units 110A and 110B based on the distance difference (|L1-L2|) calculated by the distance difference calculation unit 124.

[0047] Fig. 3 is a diagram showing two hyperbolas satisfying formula (7). In Fig. 3, the two hyperbolas are indicated by dashed lines. The position of the smartphone 200 relative to the wireless communication units 110A and 110B is somewhere on the two hyperbolas with the reference points of the antennas 111 of the wireless communication units 110A and 110B as focal points. The positioning unit 126 can narrow down the position of the smartphone 200 to a position on the two hyperbolas, and can obtain the approximate position of the smartphone 200.

[0048] <Second positioning method> In the second positioning method, the distance difference calculation unit 124 calculates the distance difference (|L1-L2|) expressed by equation (7) using the first positioning method, and then the direction derivation unit 125 calculates the arrival direction of the packet signal from the smartphone 200 to the wireless communication units 110A and 110B, and calculates the position of the smartphone 200 relative to the wireless communication units 110A and 110B based on the two hyperbolic curves and the arrival direction.

[0049] The direction derivation unit 125 determines the direction in which a signal arrives from the smartphone 200 to the wireless communication unit 110A based on the phase difference when a packet signal is received by the multiple antennas 111 of the wireless communication unit 110A, and also determines the direction in which a signal arrives from the smartphone 200 to the wireless communication unit 110B based on the phase difference when a packet signal is received by the multiple antennas of the wireless communication unit 110B.

[0050] More specifically, the direction derivation unit 125 determines the arrival direction of the packet signal from the smartphone 200 to the wireless communication unit 110A based on the phase difference when the packet signal of the frequency f1 is received by the multiple antennas 111 of the wireless communication unit 110A. Here, the direction derivation unit 125 may determine the arrival direction based on the phase difference when the packet signal of the frequency f2 is received, or may determine two arrival directions based on the phase difference when two packet signals of the frequencies f1 and f2 are received. Here, as an example, a form in which the arrival direction is determined based on the phase difference when the packet signal of the frequency f1 is received will be described. The arrival direction of the packet signal from the smartphone 200 to the wireless communication unit 110A is an example of the first arrival direction.

[0051] Further, the direction derivation unit 125 determines the arrival direction of the packet signal from the smartphone 200 to the wireless communication unit 110B based on the phase difference when the packet signal of the frequency f1 is received by the multiple antennas 111 of the wireless communication unit 110B. Here, the direction derivation unit 125 may determine the arrival direction based on the phase difference when the packet signal of the frequency f2 is received, or may determine two arrival directions based on the phase difference when two packet signals of the frequencies f1 and f2 are received. However, as an example, a form in which the arrival direction is determined based on the phase difference when the packet signal of the frequency f1 is received will be described here. The arrival direction of the packet signal from the smartphone 200 to the wireless communication unit 110B is an example of the second arrival direction.

[0052] When the direction derivation unit 125 determines the two arrival directions in this manner, the positioning unit 126 determines the position of the smartphone 200 relative to the wireless communication units 110A and 110B based on the distance difference determined by the distance difference calculation unit 124 and the two arrival directions determined by the direction derivation unit 125.

[0053] 4 is a diagram showing two hyperbolic curves satisfying the formula (7) and the receivable areas of the wireless communication units 110A and 110B. The receivable area 110A1 of the wireless communication unit 110A represents an area in which the wireless communication unit 110A can receive a packet signal from the smartphone 200 when the smartphone 200 is present within the receivable area 110A1. The receivable area 110B1 of the wireless communication unit 110B represents an area in which the wireless communication unit 110B can receive a packet signal from the smartphone 200 when the smartphone 200 is present within the receivable area 110B1. The overlapping area 110AB1 is an overlapping area between the receivable area 110A1 and the receivable area 110B1.

[0054] 4, arrow A represents the arrival direction of a packet signal derived by direction derivation unit 125 for wireless communication unit 110A. Arrow B represents the arrival direction of a packet signal derived by direction derivation unit 125 for wireless communication unit 110B.

[0055] The position of the smartphone 200 with respect to the wireless communication units 110A and 110B is an intersection point between a vector A represented by an arrow A and a vector B represented by an arrow B, and is obtained as an intersection point located on one of the hyperbola. However, in reality, such an intersection point may not be obtained due to an error or the like. In such a case, the following can be done. The intersection point can be obtained by extending the vector A or B, and the point on the hyperbola closest to the intersection point can be obtained as the position of the smartphone 200. In the case of FIG. 4, the vector A1 can be generated by extending the vector A, and the point S2 on the hyperbola closest to the intersection point S11 of the vector A1 and the vector B can be set as the position of the smartphone 200. Therefore, the positioning unit 126 can specify the position of the smartphone 200 as the position of the intersection point S2.

[0056] <Third positioning method> In the third positioning method, the position of the smartphone 200 is located using three wireless communication units 110A, 110B, and 110C. In addition, in the third positioning method, the positioning device 100 does not derive the arrival direction using the direction derivation unit 125 as in the second positioning method. Therefore, when the positioning device 100 executes the third positioning method without executing the second positioning method, the positioning device 100 does not need to include the direction derivation unit 125.

[0057] As a premise, distance calculation unit 122 calculates distance L between wireless communication units 110A and 110B, and also calculates distance L between wireless communication units 110A and 110C. Distance calculation unit 122 calculates distance L between wireless communication units 110A and 110B in the same manner as in the synchronization process described above.

[0058] Further, the distance calculation unit 122 calculates the phase when the wireless communication unit 110C receives the packet signal of the frequency f1 transmitted from the wireless communication unit 110A and the phase when the wireless communication unit 110C receives the packet signal of the frequency f2 transmitted from the wireless communication unit 110A. And Based on this, the distance L between the wireless communication units 110A and 110C is calculated. The predetermined distance L00 is an example of a known second predetermined distance, and is, for example, the distance between a reference point of the multiple antennas 111 of the wireless communication unit 110A and a reference point of the multiple antennas 111 of the wireless communication unit 110C. The method of calculating the distance L between the wireless communication units 110A and 110C is similar to the method of calculating the distance L between the wireless communication units 110A and 110B.

[0059] In addition, the synchronization control unit 123 corrects the clocks of the wireless communication units 110A and 110B to be synchronized, similar to the synchronization processing described above, and also corrects the clocks of the wireless communication units 110A and 110C to be synchronized based on the difference between the distance L between the wireless communication units 110A and 110C calculated by the distance calculation unit 122 and a predetermined distance L00.

[0060] Distance difference calculation unit 124 calculates the distance difference between smartphone 200 and wireless communication unit 110A and the distance between smartphone 200 and wireless communication unit 110C, based on phase α5 when wireless communication unit 110C receives a packet signal of frequency f1 transmitted from smartphone 200, phase α6 when wireless communication unit 110C receives a packet signal of frequency f2 transmitted from smartphone 200, and phases α1 and α2, in a state where the clocks of wireless communication units 110A, 110B, and 110C have been corrected. Phase α5 is an example of a fifth phase, and phase α6 is an example of a sixth phase.

[0061] The positioning unit 126 determines the position of smartphone 200 relative to wireless communication units 110A, 110B, and 110C based on the distance difference determined by the distance difference calculation unit 124, between the distance between smartphone 200 and wireless communication unit 110A and the distance between smartphone 200 and wireless communication unit 110B, and the distance difference between the distance between smartphone 200 and wireless communication unit 110A and the distance between smartphone 200 and wireless communication unit 110C.

[0062] 3 are obtained based on the difference in distance between smartphone 200 and wireless communication unit 110A and the distance between smartphone 200 and wireless communication unit 110B, and two hyperbolae are similarly obtained based on the difference in distance between smartphone 200 and wireless communication unit 110A and the distance between smartphone 200 and wireless communication unit 110C. That is, four hyperbolae are obtained in the third positioning method.

[0063] Fig. 5 is a diagram showing four hyperbolas obtained by the third positioning method. In Fig. 5, similarly to Fig. 3, two hyperbolas obtained based on the difference in distance between the smartphone 200 and the wireless communication unit 110A and the smartphone 200 and the wireless communication unit 110B are shown by dashed lines. In addition, two hyperbolas obtained based on the difference in distance between the smartphone 200 and the wireless communication unit 110A and the smartphone 200 and the wireless communication unit 110C are shown by dashed lines.

[0064] The position of the smartphone 200 relative to the wireless communication units 110A and 110B is an intersection point S3, which is located outside the vehicle 10, among the intersection points of two hyperbolas indicated by dashed lines and two hyperbolas indicated by dashed lines. The positioning unit 126 can specify the position of the smartphone 200 as the position of the intersection point S3. The reason why the position of the smartphone 200 can be specified as the intersection point S3 is because the point satisfies the condition that it is located on two hyperbolas (dashed lines) obtained based on the distance difference obtained by the combination of the wireless communication units 110A and 110B, and the condition that it is located on two hyperbolas (dashed lines) obtained based on the distance difference obtained by the combination of the wireless communication units 110A and 110C.

[0065] <Modification of the third positioning method> In the third positioning method, the synchronization control unit 123 corrects the clocks of the wireless communication units 110A and 110B to be synchronized, and also corrects the clocks of the wireless communication units 110A and 110C to be synchronized. For this purpose, the distance calculation unit 122 calculates the distance L between the wireless communication units 110A and 110B, and also calculates the distance L between the wireless communication units 110A and 110C.

[0066] However, in a modified example of the third positioning method, the synchronization control unit 123 may correct the clocks of the wireless communication units 110A and 110B to be synchronized, and may also correct the clocks of the wireless communication units 110B and 110C to be synchronized. Even in this manner, the clocks of the wireless communication units 110A, 110B, and 110C can be corrected to be synchronized. In this case, the distance calculation unit 122 may calculate the distance L between the wireless communication units 110A and 110B, and the distance L between the wireless communication units 110B and 110C.

[0067] When the clocks of the wireless communication units 110A, 110B, and 110C have been corrected, the distance difference calculation unit 124 calculates the distance difference between the distance between the smartphone 200 and the wireless communication unit 110B and the distance between the smartphone 200 and the wireless communication unit 110C based on the phase α5 when the wireless communication unit 110C receives a packet signal of frequency f1 transmitted from the smartphone 200, the phase α6 when the wireless communication unit 110C receives a packet signal of frequency f2 transmitted from the smartphone 200, and the phases α3 and α4.

[0068] The positioning unit 126 determines as the position of the smartphone 200 relative to the wireless communication units 110A, 110B, and 110C a point that satisfies the conditions that it is located on two hyperbolae obtained based on the distance difference obtained by combining the wireless communication units 110A and 110B, and that it is located on two hyperbolae obtained based on the distance difference obtained by combining the wireless communication units 110B and 110C.

[0069] <4th positioning method> In the fourth positioning method, under the condition that the clocks of the wireless communication units 110A and 110B are synchronized by clock correction performed by the synchronization control unit 123, times t1 and t2 and an absolute value |L1-L2| of the distance difference between the distances L1 and L2 are calculated. Times t1 and t2 are times when the wireless communication units 110A and 110B received packet signals, respectively, and are examples of the first time and the second time, respectively. The absolute value |L1-L2| of the distance difference is calculated by the distance difference calculation unit 124 according to equation (6) as described in the first positioning method.

[0070] In the fourth positioning method, the main control unit 121 uses times t1, t2, and the speed of light c to obtain a distance difference ΔL between the distance between the smartphone 200 and the wireless communication unit 110A and the distance between the smartphone 200 and the wireless communication unit 110B. The distance difference ΔL can be expressed as in the following formula (8). Note that the difference (t1-t2) between times t1 and t2 is an example of the difference between the first time and the second time.

[0071]

number

[0072] The absolute value of the distance difference |L1-L2| calculated by the distance difference calculation unit 124 is calculated using phases α1 and α2, whereas the distance difference ΔL calculated by the main control unit 121 using times t1, t2 and the speed of light c is calculated based on times t1, t2 and the speed of light c, and is therefore more accurate than the absolute value of the distance difference |L1-L2| and can be used as an evaluation criterion for the absolute value of the distance difference |L1-L2|.

[0073] For this reason, the main control unit 121 evaluates the absolute value of the distance difference |L1-L2| using the distance difference ΔL. For the evaluation, a quality factor Q that indicates the accuracy (quality) of the distance difference L1-L2 is used. The quality factor Q can be expressed by the following equation (9) using the absolute value |ΔL| of the distance difference ΔL.

[0074]

number

[0075] Main control unit 121 evaluates the quality of distance difference L1-L2 based on the difference between times t1 and t2 according to equation (9) and distance difference L1-L2 calculated by distance difference calculation unit 124. According to the fourth positioning method, it is possible to calculate a quality coefficient Q for evaluating the quality of the absolute value |L1-L2| of the distance difference calculated by distance difference calculation unit 124. Quality coefficient Q can be used, for example, when evaluating distance difference L1-L2 calculated by distance difference calculation unit 124 when determining the position of smartphone 200 by the first positioning method, the second positioning method, and the third positioning method.

[0076] As described above, in the positioning device 100, the synchronization control unit 123 corrects the phase of the clock of the wireless communication unit 110 based on the difference (L-L0) between the distance L calculated by the distance calculation unit 122 and the predetermined distance L0 so that the clocks of the wireless communication units 110 are synchronized. The clock phase can be corrected with an accuracy of 1 ns (nanosecond) level.

[0077] Therefore, it is possible to provide a positioning device 100 capable of correcting the phases of the clocks of the wireless communication units 110 with high accuracy.

[0078] Furthermore, the distance calculation unit 122 can reliably and easily determine the distance L between the wireless communication units 110 according to equations (1) to (5), and the synchronization control unit 123 corrects the phase of the clock of the wireless communication unit 110 based on the difference (L-L0) between the distance L calculated by the distance calculation unit 122 and a predetermined distance L0, so that the clock phase can be reliably and easily corrected with an accuracy of 1 ns (nanosecond) level.

[0079] Also, in the first proposal, the positioning unit 126 can narrow down the position of the smartphone 200 to a position on two hyperbolae (hyperbolae for the wireless communication units 110A and 110B) represented by the distance difference (|L1-L2|) calculated by the distance difference calculation unit 124, and can calculate the approximate position of the smartphone 200. The two hyperbolae are obtained by positioning with the TOA using the wireless communication units 110A and 110B. Therefore, it is possible to provide a positioning device 100 that can correct the phases of the clocks of the wireless communication units 110 with high accuracy and calculate the approximate position of the smartphone 200 by the TOA.

[0080] In the second proposal, the positioning unit 126 can specify the intersection of two hyperbolas (hyperbolas for the wireless communication units 110A and 110B) representing the distance difference calculated by the distance difference calculation unit 124 and the arrival direction of the packet signal calculated by the direction derivation unit 125 for the wireless communication units 110A and 110B as the position of the smartphone 200. The two hyperbolas are obtained by positioning with the TOA using the wireless communication units 110A and 110B, and the arrival direction is obtained by angle detection with the AOA using the wireless communication units 110A and 110B. Therefore, it is possible to provide a positioning device 100 that can accurately correct the phase of the clocks of the wireless communication units 110 and specify the position of the smartphone 200 by combining the TOA and the AOA.

[0081] In the third proposal, the intersection of two hyperbolas obtained based on the difference in distance between the smartphone 200 and the wireless communication units 110A and 110B and two hyperbolas obtained based on the difference in distance between the smartphone 200 and the wireless communication units 110A and 110C can be specified as the position of the smartphone 200. The four hyperbolas are obtained by positioning at the TOA using the wireless communication units 110A and 110B and by positioning at the TOA using the wireless communication units 110A and 110C. Therefore, it is possible to provide a positioning device 100 that can accurately correct the phases of the clocks of the wireless communication units 110 and specify the position of the smartphone 200 by positioning at the TOA.

[0082] In addition, it is also possible to identify the position of smartphone 200 as the intersection of two hyperbolas obtained based on the distance difference between smartphone 200 and wireless communication units 110A and 110B and two hyperbolas obtained based on the distance difference between smartphone 200 and wireless communication units 110B and 110C.

[0083] The above describes an exemplary embodiment of a positioning device and a clock correction method of the present disclosure. However, the present disclosure is not limited to the specifically disclosed embodiments, and various modifications and variations are possible without departing from the scope of the claims.

[0084] This international application claims priority to Japanese patent application No. 2021-196786, filed on December 3, 2021, the entire contents of which are incorporated herein by reference. [Explanation of symbols]

[0085] 10 Vehicles 100 Positioning device 110, 110A, 110B, 110C Wireless communication section 120 ECU 122 Distance calculation unit 123 Synchronization control section 124 Distance difference calculation unit 125 Direction derivation part 126 Positioning unit 200 Smartphones

Claims

1. A positioning device that measures the position of a mobile communication unit, A first wireless communication unit; A second wireless communication unit disposed at a known first predetermined distance from the first wireless communication unit; a distance calculation unit that calculates a distance between the first wireless communication unit and the second wireless communication unit based on a phase of a signal of a first frequency transmitted from the first wireless communication unit when the second wireless communication unit receives the signal of a second frequency transmitted from the first wireless communication unit; a synchronization control unit that corrects clocks of the first wireless communication unit and the second wireless communication unit so as to be synchronized based on a difference between the distance calculated by the distance calculation unit and the first predetermined distance; A positioning device comprising:

2. Let L0 be the first predetermined distance, n be the wave number of the signal of the first frequency between the first wireless communication unit and the second wireless communication unit and the wave number of the signal of the second frequency between the first wireless communication unit and the second wireless communication unit, P1 be the phase when the signal of the first frequency is received by the second wireless communication unit, and P2 be the phase when the signal of the second frequency is received by the second wireless communication unit. The positioning device according to claim 1 , wherein the distance calculation unit calculates the distance L between the first wireless communication unit and the second wireless communication unit according to the following formula: [0010]

3. a distance difference calculation unit that calculates a distance difference between a distance between the mobile communication unit and the first wireless communication unit and a distance between the mobile communication unit and the second wireless communication unit based on a first phase when the first wireless communication unit receives a first signal of the first frequency transmitted from the mobile communication unit, a second phase when the first wireless communication unit receives a second signal of the second frequency transmitted from the mobile communication unit, a third phase when the second wireless communication unit receives the first signal of the first frequency transmitted from the mobile communication unit, and a fourth phase when the second wireless communication unit receives the second signal of the second frequency transmitted from the mobile communication unit; a positioning unit that determines a position of the mobile communication unit with respect to the first wireless communication unit and the second wireless communication unit based on the distance difference calculated by the distance difference calculation unit; The positioning device according to claim 1 or 2, further comprising:

4. the first wireless communication unit and the second wireless communication unit each have a plurality of antennas; a direction derivation unit that determines a first direction of arrival of the signal from the mobile communication unit to the first wireless communication unit based on a phase difference when the signal is received by the multiple antennas of the first wireless communication unit, or determines a second direction of arrival of the signal from the mobile communication unit to the second wireless communication unit based on a phase difference when the signal is received by the multiple antennas of the second wireless communication unit, 4. The positioning device according to claim 3, wherein the positioning unit determines a position of the mobile communication unit relative to the first wireless communication unit and the second wireless communication unit based on the distance difference determined by the distance difference calculation unit and the first arrival direction or the second arrival direction determined by the direction derivation unit.

5. 5. The positioning device according to claim 4, wherein the direction derivation unit determines the first arrival direction from a phase difference when at least one of the first signal and the second signal is received by the multiple antennas of the first wireless communication unit, or determines the second arrival direction from a phase difference when at least one of the first signal and the second signal is received by the multiple antennas of the second wireless communication unit.

6. a third wireless communication unit disposed at a known second predetermined distance from the first wireless communication unit; the distance calculation unit calculates a distance between the first wireless communication unit and the third wireless communication unit based on a phase of the signal of the first frequency transmitted from the first wireless communication unit when it is received by the third wireless communication unit and a phase of the signal of the second frequency transmitted from the first wireless communication unit when it is received by the third wireless communication unit; the synchronization control unit corrects clocks of the first wireless communication unit and the third wireless communication unit based on a difference between the distance between the first wireless communication unit and the third wireless communication unit calculated by the distance calculation unit and the second predetermined distance so that clocks of the first wireless communication unit and the third wireless communication unit are synchronized; the distance difference calculation unit calculates a distance difference between a distance between the mobile communication unit and the first wireless communication unit and a distance between the mobile communication unit and the third wireless communication unit, based on a fifth phase when the third wireless communication unit receives the first signal of the first frequency transmitted from the mobile communication unit, a sixth phase when the third wireless communication unit receives the second signal of the second frequency transmitted from the mobile communication unit, and the first phase and the second phase; 4. The positioning device of claim 3, wherein the positioning unit calculates a position of the mobile communication unit relative to the first wireless communication unit, the second wireless communication unit, and the third wireless communication unit based on a distance difference calculated by the distance difference calculation unit between the distance between the mobile communication unit and the first wireless communication unit and the distance between the mobile communication unit and the second wireless communication unit, and a distance difference between the distance between the mobile communication unit and the first wireless communication unit and the distance between the mobile communication unit and the third wireless communication unit.

7. a third wireless communication unit disposed at a known second predetermined distance from the second wireless communication unit; the distance calculation unit calculates a distance between the second wireless communication unit and the third wireless communication unit based on a phase of the signal of the first frequency transmitted from the second wireless communication unit when it is received by the third wireless communication unit and a phase of the signal of the second frequency transmitted from the second wireless communication unit when it is received by the third wireless communication unit; the synchronization control unit corrects clocks of the second wireless communication unit and the third wireless communication unit based on a difference between the distance between the second wireless communication unit and the third wireless communication unit calculated by the distance calculation unit and the second predetermined distance so that clocks of the second wireless communication unit and the third wireless communication unit are synchronized; the distance difference calculation unit calculates a distance difference between a distance between the mobile communication unit and the second wireless communication unit and a distance between the mobile communication unit and the third wireless communication unit, based on a fifth phase when the third wireless communication unit receives the first signal of the first frequency transmitted from the mobile communication unit, a sixth phase when the third wireless communication unit receives the second signal of the second frequency transmitted from the mobile communication unit, the third phase, and the fourth phase; 4. The positioning device of claim 3, wherein the positioning unit calculates a position of the mobile communication unit relative to the first wireless communication unit, the second wireless communication unit, and the third wireless communication unit based on a distance difference calculated by the distance difference calculation unit between the distance between the mobile communication unit and the first wireless communication unit and the distance between the mobile communication unit and the second wireless communication unit, and a distance difference between the distance between the mobile communication unit and the second wireless communication unit and the distance between the mobile communication unit and the third wireless communication unit.

8. 4. The positioning device of claim 3, wherein the quality of the distance difference is evaluated based on a difference between a first time and a second time at which the first wireless communication unit and the second wireless communication unit receive signals transmitted from the mobile communication unit with the clocks of the first wireless communication unit and the second wireless communication unit corrected by the synchronization control unit so that they are synchronized, and the distance difference calculated by the distance difference calculation unit.

9. A clock correction method for correcting a clock of a positioning device that measures the position of a mobile communication unit, comprising the steps of: The positioning device is A first wireless communication unit; A second wireless communication unit disposed at a known first predetermined distance from the first wireless communication unit; a distance calculation unit that calculates a distance between the first wireless communication unit and the second wireless communication unit based on a phase of a signal of a first frequency transmitted from the first wireless communication unit when the second wireless communication unit receives the signal of a second frequency transmitted from the first wireless communication unit; Including, A clock correction method comprising: correcting clocks of the first wireless communication unit and the second wireless communication unit so as to be synchronized based on a difference between a distance calculated by the distance calculation unit and the first predetermined distance.

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