Wireless ranging system

Abstract

The wireless distance measurement system (1) comprises: a distance measurement terminal (100) which transmits a distance measurement signal; and a distance measurement terminal (200) which, after receiving the distance measurement signal, continuously transmits a response signal to the distance measurement terminal (100) for the distance measurement signal for a plurality of times. The system is characterized in that the distance measurement terminal (100) measures the elapsed time from the transmission of the distance measurement signal each time it receives each of a plurality of response signals, and calculates the relative distance between the distance measurement terminal (100) and the distance measurement terminal (200) based on the transmission time of each of the plurality of response signals calculated using the elapsed time.

Description

Technical Field

[0001] The present invention relates to a wireless distance measurement system, a distance measurement terminal, a control circuit, a storage medium and a wireless distance measurement method for measuring the relative distance between terminals using radio waves. Background Art

[0002] As a method of measuring the relative distance between terminals using radio waves, a two-way ranging (TWR) method that calculates the relative distance between terminals based on the time when a ranging signal is sent from a ranging terminal to a measured terminal and the time when a response signal to the ranging signal is received by the ranging terminal has attracted attention. Patent document 1 discloses a wireless ranging technology that combines a wireless communication technology using nanosecond pulses called UWB (Ultra-Wide Band) with the TWR method.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent No. 3649404 Summary of the invention

[0006] Problems to be solved by the invention

[0007] However, according to the above-mentioned prior art, the relative distance is estimated using the transmission time of the signal during one round trip between the ranging terminal and the terminal being ranged. Therefore, there is the following problem: sometimes, in proportion to the time required for the reception processing of each terminal, the time required for one ranging becomes longer, the ranging frequency decreases, and the ranging accuracy decreases. For example, when the ranging frequency decreases, the influence of the error included in one ranging becomes greater, and the ranging accuracy decreases. In addition, when the ranging frequency decreases, if the moving speed of the terminal being ranged is fast, the relative distance between the terminal being ranged has changed at the time of calculating the relative distance, and the ranging accuracy decreases.

[0008] The present invention has been made in view of the above-mentioned situation, and an object of the present invention is to obtain a wireless distance measurement system capable of improving distance measurement accuracy.

[0009] Means for solving problems

[0010] In order to solve the above-mentioned problems and achieve the purpose, the wireless ranging system of the present invention comprises: a ranging terminal, which sends a ranging signal; and a terminal to be ranged, which sends a response signal to the ranging signal to the ranging terminal multiple times in succession after receiving the ranging signal, and each time the ranging terminal receives each of the multiple response signals, measures the elapsed time from the transmission of the ranging signal, and calculates the relative distance between the ranging terminal and the terminal to be ranged based on the transmission time of each of the multiple response signals calculated using the elapsed time.

[0011] Effects of the Invention

[0012] The wireless distance measurement system of the present invention has the effect of improving the distance measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a diagram showing the configuration of a wireless distance measurement system according to Embodiment 1.

[0014] Figure 2 It is used to implement Figure 1 A diagram of dedicated hardware showing the functions of a ranging terminal and a ranging terminal.

[0015] Figure 3 It is used to implement Figure 1 The diagram shows the structure of the control circuit of the functions of the ranging terminal and the terminal to be ranging.

[0016] Figure 4 It is used to illustrate Figure 1 A diagram illustrating the operation of the wireless ranging system.

[0017] Figure 5 This is a diagram showing the structure of a wireless distance measurement system according to the second embodiment.

[0018] Figure 6 This is a diagram showing the structure of a wireless distance measurement system according to a third embodiment.

[0019] Figure 7 It is used to illustrate Figure 6 A diagram illustrating the operation of the wireless ranging system. DETAILED DESCRIPTION

[0020] Hereinafter, a wireless ranging system, a ranging terminal, a control circuit, a storage medium, and a wireless ranging method according to embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0021] Implementation Method 1

[0022] Figure 1 1 is a diagram showing a configuration of a wireless distance measurement system 1 according to Embodiment 1. The wireless distance measurement system 1 includes a distance measurement terminal 100 and a distance measurement terminal 200. The distance measurement terminal 100 measures the relative distance between the distance measurement terminal 100 and the distance measurement terminal 200 using a wireless signal. Figure 1 In the figure, only the structural elements necessary for explaining the technology of this embodiment are shown, and general structures are omitted.

[0023] The distance measuring terminal 100 and the distance measured terminal 200 respectively include a transceiver antenna 10 for transmitting and receiving wireless signals for distance measurement, a transmitter 20 for generating wireless signals, a receiver 30 for receiving wireless signals and processing the received signals, and a controller 40 for controlling the transmitter 20 and the receiver 30 .

[0024] In addition, the ranging terminal 100 and the ranged terminal 200 are wireless devices capable of transmitting and receiving wireless signals for ranging. As described above, the ranging terminal 100 and the ranged terminal 200 each have the same components as wireless devices and are marked with the same symbols, but the functions of each component may be common when it is set in the ranging terminal 100 and when it is set in the ranged terminal 200, or may be executed only when it is set in the ranging terminal 100 or the ranged terminal 200.

[0025] The functions of the transmitting unit 20, receiving unit 30 and control unit 40 of the ranging terminal 100 and the measured terminal 200 may be implemented by a dedicated circuit or by a general circuit that executes a program. When the functions of the transmitting unit 20, receiving unit 30 and control unit 40 are implemented by a dedicated circuit, the ranging terminal 100 and the measured terminal 200 have Figure 2 The processing circuit 90 is shown. Figure 2 It is used to implement Figure 1 The figure shows the functional dedicated hardware of the ranging terminal 100 and the measured terminal 200. The processing circuit 90 is a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof.

[0026] When the processing circuit is implemented by a general circuit, the general circuit is, for example, Figure 3 The control circuit 91 of the structure shown. Figure 3 It is used to implement Figure 1 FIG. 9 is a diagram showing the structure of the control circuit 91 for controlling the functions of the ranging terminal 100 and the range-measured terminal 200. Figure 3As shown, the control circuit 91 has a CPU (Central Processing Unit) 92 and a memory 93. The CPU 92 is a processor, and is also called a calculation unit, a microprocessor, a microcomputer, a DSP (Digital Signal Processor), etc. The memory 93 is, for example, a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable ROM), an EEPROM (registered trademark) (Electrically EPROM), or other nonvolatile or volatile semiconductor memory, a magnetic disk, a floppy disk, an optical disk, a high-density disk, a mini disk, a DVD (Digital Versatile Disk), etc.

[0027] When the above-mentioned processing circuit is implemented by the control circuit 91, the CPU 92 reads out and executes the program corresponding to the processing of each component stored in the memory 93. In addition, the memory 93 is also used as a temporary memory in each process executed by the CPU 92. In addition, the program executed by the CPU 92 can be provided via a communication path, or can be provided in a state stored in a storage medium. In addition, it is also possible that part of the functions of the ranging terminal 100 and the measured terminal 200 are implemented using a dedicated circuit, and part of them are implemented using a program and the CPU 92.

[0028] Figure 4 It is used to illustrate Figure 1 1 is a diagram showing the operation of the wireless ranging system 1. The transmitting unit 20 of the ranging terminal 100 transmits the ranging signal 101 to the ranging terminal 200. The receiving unit 30 of the ranging terminal 200 receives the ranging signal 101. After the receiving unit 30 of the ranging terminal 200 completes the reception process of the ranging signal 101, the control unit 40 instructs the transmitting unit 20 to continuously transmit a plurality of response signals 201-1, 201-2, and 201-3 to the ranging terminal 100 in response to the ranging signal 101.

[0029] Each time the receiving unit 30 of the ranging terminal 100 receives each of the response signals 201-1, 201-2, and 201-3, the control unit 40 of the ranging terminal 100 measures the transmission time T of each of the response signals 201-1, 201-2, and 201-3. ToF_1 、T ToF_2 、T ToF_3 Transmission time T ToF_nThe transmission time T is the time from when the measured terminal 200 sends the response signal 201-n to when the measuring terminal 100 receives the response signal 201-n. ToF_n (n≥2) is represented by the following mathematical formula (1).

[0030] [Mathematical formula 1]

[0031]

[0032] Among them, T in mathematical formula (1) total_n is the time elapsed from the transmission of the ranging signal 101 by the ranging terminal 100 to the reception of the response signal 201 - n. When n ≥ 2, T reply_n T is the time from when the measured terminal 200 sends the response signal 201-(n-1) to when it sends the response signal 201-n. ToF_1 The calculation can be performed using the following mathematical formula (2) in the same manner as in the conventional TWR technology.

[0033] [Mathematical formula 2]

[0034]

[0035] Among them, T reply_1 The time from when the measured terminal 200 receives the ranging signal 101 to when it sends the response signal 201-1. The measured terminal 200 sends the response signal 201-1 immediately after completing the reception process of the ranging signal 101. Therefore, T reply_1 Indicates the receive processing time.

[0036] When n≥2, T reply_n The control unit 40 uses multiple transmission times T ToF_n The relative distance between the ranging terminal 100 and the ranging terminal 200 is calculated multiple times based on the various transmission times and communication speeds in the ranging terminal 100.

[0037] As described above, in the wireless ranging system 1 of Embodiment 1, after the ranging terminal 100 transmits the ranging signal 101, the measured terminal 200 continuously transmits a plurality of response signals 201-1, 201-2, and 201-3 to the ranging signal 101 to the ranging terminal 100. Each time the ranging terminal 100 receives each of the plurality of response signals 201-1, 201-2, and 201-3, it measures the elapsed time T from the transmission of the ranging signal 101 to the reception of each of the plurality of response signals 201-1, 201-2, and 201-3. total_n , according to the use of T total_nThe calculated transmission time T of each of the plurality of response signals 201-1, 201-2, and 201-3 is ToF_n , calculate the relative distance between the ranging terminal 100 and the ranging terminal 200.

[0038] Here, the measured terminal 200 sends a plurality of response signals 201-1, 201-2, and 201-3 to one ranging signal 101. The ranging terminal 100 can calculate the same number of relative distances as the response signals 201-1, 201-2, and 201-3. Therefore, compared with the case where one response signal 201-n is sent to one ranging signal 101, the ranging terminal 100 can increase the ranging frequency. Therefore, even when the measured terminal 200 moves at a high speed, the relative distance can be calculated in real time. In addition, by increasing the ranging frequency, the calculation results of multiple relative distances can be averaged. Therefore, the ranging accuracy can be improved.

[0039] Furthermore, the above description describes the ranging process using the response signals 201 - 1 , 201 - 2 , and 201 - 3 for one ranging signal 101 , but the ranging terminal 200 may send two response signals 201 - n or four or more response signals 201 - n for one ranging signal 101 .

[0040] In addition, there is no particular limitation on the type of the distance measuring terminal 100 and the distance measured terminal 200 as long as they have the function of transmitting and receiving wireless signals. The distance measuring terminal 100 and the distance measured terminal 200 may be mobile terminals or fixed terminals.

[0041] Implementation Method 2

[0042] Figure 5 2 is a diagram showing the structure of a wireless distance measurement system 2 according to Embodiment 2. The wireless distance measurement system 2 is a wireless communication system having a communication terminal 300a and a communication terminal 300b. The communication terminal 300a measures the relative distance between the communication terminal 300a and the communication terminal 300b using a wireless signal. Figure 5 In the figure, only the structural elements necessary for explaining the technology of this embodiment are shown, and general structures are omitted.

[0043] The communication terminals 300a and 300b each include a transceiver antenna 11 for transmitting and receiving wireless signals, a transmitter 21 for generating wireless signals, a receiver 31 for receiving wireless signals and processing the received signals, and a controller 41 for controlling the transmitter 21 and the receiver 31. The communication terminals 300a and 300b transmit and receive wireless signals obtained by adding communication signals to wireless signals for distance measurement.

[0044] The communication terminal 300a has a communication function in addition to the function of the ranging terminal 100. In addition, the communication terminal 300b has a communication function in addition to the function of the ranged terminal 200. The communication terminal 300a can attach a communication signal to the ranging signal and send it. For example, the communication terminal 300a attaches a communication signal indicating the number of times the communication terminal 300b continuously sends a response signal, i.e., the number of consecutive transmissions, to the ranging signal and sends it. In this case, the communication terminal 300b continuously sends the response signal according to the number of consecutive transmissions indicated by the communication signal attached to the ranging signal. For example, in the case where a communication signal indicating that the number of consecutive transmissions is "5" is attached to the ranging signal, the communication terminal 300b continuously sends the response signal 5 times to one ranging signal.

[0045] In addition, the communication terminal 300b can attach a communication signal to at least one of the multiple response signals sent continuously and send it to the communication terminal 300a. For example, the communication terminal 300b can attach a communication signal indicating a sequence number to the response signal and send it to the communication terminal 300a. The sequence number indicates the order in which the response signal is sent. The communication terminal 300a can detect an error in the response signal using the sequence number.

[0046] In addition, the hardware structure of the communication terminals 300a and 300b is the same as that of the ranging terminal 100 and the measured terminal 200, so the description is omitted here. In addition, except for the above-mentioned communication function, the operation of the communication terminal 300a is the same as that of the ranging terminal 100, and except for the above-mentioned communication function, the operation of the communication terminal 300b is the same as that of the measured terminal 200, so the description is omitted here.

[0047] As described above, the wireless distance measurement system 2 of the second embodiment can improve the distance measurement accuracy similarly to the wireless distance measurement system 1. In addition, the wireless distance measurement system 2 has a communication function, and therefore can specify the number of consecutive transmissions of the response signal, or detect consecutive errors using a sequence number. In this way, by adding a communication function, a function that cannot be achieved with only the distance measurement function can be realized.

[0048] Implementation 3

[0049] Figure 6 3 is a diagram showing the structure of a wireless distance measurement system 3 according to Embodiment 3. The wireless distance measurement system 3 is a wireless communication system having a communication terminal 300c, a communication terminal 300d, and a communication terminal 300e. The communication terminal 300c uses a wireless signal to measure the relative distance between the communication terminal 300c and the communication terminal 300d, and the relative distance between the communication terminal 300c and the communication terminal 300e. Figure 6 In the figure, only the structural elements necessary for explaining the technology of this embodiment are shown, and general structures are omitted.

[0050] The configurations of the communication terminals 300c, 300d, and 300e are the same as those of the communication terminals 300a and 300b, and therefore detailed descriptions thereof are omitted here.

[0051] The communication terminal 300c has a communication function in addition to the function of the distance measuring terminal 100. The communication terminals 300d and 300e each have a communication function in addition to the function of the distance measured terminal 200. The communication terminal 300c can measure the relative distances with a plurality of communication terminals 300d and 300e.

[0052] Figure 7 It is used to illustrate Figure 6 2 is a diagram showing the operation of the wireless distance measurement system 3. The transmission unit 21 of the communication terminal 300c transmits the wireless signal 301 to the plurality of communication terminals 300d and 300e respectively. At this time, the wireless signal 301 includes a distance measurement signal and a communication signal. For example, the communication signal indicates the plurality of communication terminals 300d and 300e as distance measurement objects and the distance measurement order of the plurality of communication terminals 300d and 300e.

[0053] Upon receiving the wireless signal 301, the communication terminal 300d confirms the distance measurement object indicated by the communication signal contained in the wireless signal 301, and determines whether the communication terminal 300d is included in the distance measurement object. If included in the distance measurement object, the communication terminal 300d further confirms the distance measurement order of the communication terminal 300d indicated by the communication signal contained in the wireless signal 301. Similarly, upon receiving the wireless signal 301, the communication terminal 300e confirms the distance measurement object indicated by the communication signal contained in the wireless signal 301, and determines whether the communication terminal 300e is included in the distance measurement object. If included in the distance measurement object, the communication terminal 300e further confirms the distance measurement order of the communication terminal 300e indicated by the communication signal contained in the wireless signal 301.

[0054] The communication terminal 300d transmits the response signal 302 to the ranging signal included in the wireless signal 301 to the communication terminal 300c multiple times in succession according to the confirmed ranging order. The communication terminal 300e transmits the response signal 302 to the ranging signal included in the wireless signal 301 to the communication terminal 300c multiple times in succession according to the confirmed ranging order. Specifically, the communication terminal 300d whose ranging order is "1" transmits the response signal 302 immediately after completing the reception process as usual, and then transmits the response signal 302 at a certain interval. In order to prevent the transmission signal from colliding with the communication terminal 300d, the communication terminal 300e whose ranging order is "2" transmits the response signal 302 after a predetermined offset time has passed since the completion of the reception process of the wireless signal 301, and then transmits the response signal 302 at a certain interval.

[0055] The communication terminal 300c can measure the elapsed time from the transmission of the wireless signal 301 each time it receives a plurality of response signals 302, and calculate the relative distance between the communication terminal 300c and the communication terminal 300d, and the relative distance between the communication terminal 300c and the communication terminal 300e based on the transmission time of each of the plurality of response signals 302 calculated using the elapsed time. In addition, the relative distance calculation method is the same as that of the first embodiment, and therefore, a detailed description thereof is omitted here.

[0056] In the above, the communication terminal 300c uses two communication terminals 300d and 300e as distance measurement targets, but the present embodiment is not limited to this example. For example, the communication terminal 300c may use three or more communication terminals as distance measurement targets.

[0057] As described above, the wireless distance measurement system 3 of the third embodiment can improve the distance measurement accuracy similarly to the wireless distance measurement system 1. In addition, the wireless distance measurement system 3 calculates the relative distance between one communication terminal 300c and a plurality of communication terminals 300d and 300e. Even in the case of a plurality of distance measurement objects, the distance measurement order can be notified to the plurality of communication terminals 300d and 300e respectively using the communication function. Therefore, the plurality of communication terminals 300d and 300e as distance measurement objects can adjust the transmission time respectively so that the response signal 302 sent by the communication terminal 300d does not conflict with the response signal 302 sent by the communication terminal 300e.

[0058] The structures shown in the above embodiments are merely examples, and may be combined with other known technologies, the embodiments may be combined with each other, and part of the structures may be omitted or modified within a scope not departing from the gist.

[0059] Explanation of symbols

[0060] 1, 2, 3: wireless ranging system; 10, 11: transmitting and receiving antennas; 20, 21: transmitting unit; 30, 31: receiving unit; 40, 41: control unit; 90: processing circuit; 91: control circuit; 92: CPU; 93: memory; 100: ranging terminal; 101: ranging signal; 200: ranging terminal; 201-1, 201-2, 201-3, 302: response signal; 300a, 300b, 300c, 300d, 300e: communication terminal; 301: wireless signal.

Claims

1. A wireless ranging system, characterized in that: The wireless ranging system has: a ranging terminal that transmits a wireless signal including a ranging signal and a communication signal indicating a ranging order of a first ranging terminal and a second ranging terminal; a first measured terminal, which, upon receiving the wireless signal, sends a first response signal to the ranging terminal after a first offset time based on the ranging sequence, and then sends the first response signal to the ranging terminal multiple times at a first time interval; as well as a second measured terminal, which, upon receiving the wireless signal, sends a second response signal to the ranging terminal after a second offset time based on the ranging sequence, and then sends the second response signal to the ranging terminal multiple times at a second time interval, The ranging terminal measures the time elapsed from the transmission of the ranging signal each time each of the plurality of first response signals is received, calculates the transmission time of each of the plurality of first response signals transmitted using the plurality of elapsed times until each of the plurality of first response signals transmitted is received, the first offset time, and the first time interval, and calculates the relative distance between the ranging terminal and the first ranging terminal according to each of the plurality of first response signals using the plurality of calculated transmission times. The ranging terminal measures the time elapsed from the transmission of the ranging signal each time each second response signal among the plurality of second response signals is received, calculates the transmission time of each of the plurality of second response signals transmitted multiple times using the plurality of elapsed times until each of the plurality of second response signals transmitted multiple times is received, the second offset time and the second time interval, and calculates the relative distance between the ranging terminal and the second ranging terminal according to each of the second response signals using the plurality of calculated transmission times. The first offset time, the first time interval, the second offset time, and the second time interval are set so that the ranging terminal can alternately receive the first response signal and the second response signal one signal at a time.

2. The wireless ranging system according to claim 1, characterized in that: The communication signal includes a first continuous transmission count indicating the number of times the first distance measured terminal continuously transmits the first response signal and a second continuous transmission count indicating the number of times the second distance measured terminal continuously transmits the second response signal.

3. The wireless ranging system according to claim 2, characterized in that: The first distance measured terminal sends the first response signal according to the first continuous transmission number, and the second distance measured terminal sends the second response signal according to the second continuous transmission number.

4. The wireless ranging system according to any one of claims 1 to 3, characterized in that: The first ranging terminal adds a sequence number indicating a transmission order of the first response signal to the first response signal, and the second ranging terminal adds a sequence number indicating a transmission order of the second response signal to the second response signal.

5. The wireless ranging system according to claim 4, characterized in that: The ranging terminal detects errors in the first response signal and the second response signal using the sequence number.

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