A bluetooth ranging method and system, a vehicle

Abstract

The application provides a Bluetooth ranging method, comprising: a master node sends a first signal to a slave node, the signal flight time of the first signal reaching the slave node is T1, and the intensity indication of the first signal is RSSI1; the slave node sends a second signal to the master node, the signal flight time of the second signal reaching the master node is T2, and the intensity indication of the second signal is RSSI2; an equation is constructed to solve the signal flight time measurement deviation of the first signal and the second signal: d=(T1+Delta t1)*C, wherein C is the speed of light. The ranging method in the application can effectively combine two ranging methods, fuse and correct the two kinds of measurement information, and improve the overall measurement accuracy of the ranging system; and the ranging method does not need other hardware settings, and can be realized by using the existing Bluetooth device, which is convenient and efficient.

Description

Technical Field

[0001] This invention relates to the field of communications, and more particularly to a Bluetooth ranging method and system, and a vehicle. Background Technology

[0002] In the prior art, distance measurement using Bluetooth Low Energy devices typically involves two methods: distance measurement between nodes based on Time of Arrival (ToF) and Received Signal Strength Indication (RSSI).

[0003] The basic ToF ranging process includes: measuring the time required for signals to be transmitted from the transmitting side in the direction of initiation and the reflecting side in the direction of reflection, and then calculating the average of the two ranging results. This ranging method is susceptible to factors such as clock frequency deviation between the transmitting and receiving parties, antenna delay, and multipath propagation, leading to a decrease in ranging accuracy. Furthermore, when the distance between the transmitting and receiving parties is close, the negative impact of interference factors is more pronounced.

[0004] Another ranging method is based on modeling the propagation loss of wireless signals, calculated using the following formula:

[0005]

[0006] in, and These represent the actual distance and the reference distance, respectively. and These represent RSSI at actual distance and reference distance, respectively. It is the path loss index. This is random noise. In reality, the larger the actual distance, the more... The greater the fluctuation, the more suitable the above ranging method is for use when the distance between the transmitter and receiver is relatively short.

[0007] As can be seen from the above, neither of the two ranging methods is applicable to all distance ranges, and each has its own advantages and disadvantages at different distance ranges. Therefore, there is an urgent need to provide a ranging method and system that can cover all distance ranges and has high accuracy. Summary of the Invention

[0008] To improve the accuracy of distance measurement, the present invention aims to provide a Bluetooth ranging method. Specifically, the present invention discloses a Bluetooth ranging method, comprising:

[0009] The master node sends a first signal to the slave node. The signal flight time of the first signal to the slave node is T1, and the strength indication of the first signal is RSSI1.

[0010] The slave node sends a second signal to the master node, the signal flight time of the second signal to the master node is T2, and the strength indication of the second signal is RSSI2;

[0011] Based on the flight time T1+ of the first signal Δt 1 With Intensity Indicator RSSI 1+ A 1 Construct a first distance calculation equation for the first signal, based on the flight time T2+ of the second signal. Δt 2 With Intensity Indicator RSSI 2+ A 2 Construct a second distance calculation equation for the second signal.

[0012] in Δt 1 and A 1 These are the measurement deviations of the signal flight time and intensity indication of the first signal, respectively. D t 2 and A 2 These are the measurement deviations of the signal flight time and intensity indication of the second signal, respectively;

[0013] When both the first distance calculation equation and the second distance calculation equation are satisfied, and the flight times of the first and second signals are equal, the solution can make... Get the minimum value Δt 1 、D t 2 Where w1 and w2 are the weight ratios and the sum of w1 and w2 is 1; calculate the distance d according to the following formula:

[0014] d= , where C is the speed of light.

[0015] Preferably, the solution is obtained according to the following formula. Δt 1 ,Δt 2 ,

[0016] ,

[0017] Where A is the RSSI of the signal at a distance of 1 meter, and n is the path loss exponent.

[0018] Preferably, the master node sends a first signal to the slave node, and the signal flight time of the first signal to the slave node is T1, constructing formula (1):

[0019] d= Formula (1);

[0020] The slave node sends a second signal to the master node, and the signal flight time of the second signal to the master node is T2, thus constructing formula (2):

[0021] d= Formula (2).

[0022] Preferably, the intensity indicator of the first signal is RSSI1, and formula (3) is constructed.

[0023] d= Formula (3);

[0024] The intensity indication of the second signal is RSSI2, and formula (4) is constructed.

[0025] d= Formula (4);

[0026] The first distance equation is = The second distance equation is: = .

[0027] Preferably, w1 and w2 are equal.

[0028] In another aspect, the present invention provides a Bluetooth ranging system, including a master node, a slave node, and a computing unit;

[0029] The master node is used to send a first signal to the slave node. The signal flight time of the first signal to the slave node is T1, and the strength indication of the first signal is RSSI1.

[0030] The slave node is used to send a second signal to the master node, the signal flight time of the second signal to the master node is T2, and the strength indication of the second signal is RSSI2;

[0031] The calculation unit is used to calculate based on the flight time T1+ of the first signal. Δt 1 With Intensity Indicator RSSI 1+ A 1 Construct a first distance equation for the first signal, based on the flight time T2+ of the second signal. Δt 2 With Intensity Indicator RSSI2+ A 2 Construct a second distance equation for the second signal.

[0032] in Δt 1 and A 1 These are the measurement deviations of the signal flight time and intensity indication of the first signal, respectively. D t 2 and A 2 These are the measurement deviations of the signal flight time and intensity indication of the second signal, respectively;

[0033] When both the first distance calculation equation and the second distance calculation equation are satisfied, and the flight times of the first and second signals are equal, the calculation unit is used to solve for the distance calculation equation that enables the first and second signals to be equal. Get the minimum value Δt 1 ,Δt 2 , where w1 and w2 are the weight ratios and the sum of w1 and w2 is 1;

[0034] The calculation unit is used to calculate the distance d according to the following formula:

[0035] d= , where C is the speed of light.

[0036] Preferably, the calculation unit is used to solve the following formula. Δt 1 ,Δt 2 ,

[0037] , where A is the RSSI of the signal at a distance of 1 meter, and n is the path loss exponent.

[0038] Preferably, the master node is used to send a first signal to the slave node, the signal flight time of the first signal to the slave node is T1, and the formula (1) is constructed as follows:

[0039] d= Formula (1);

[0040] The slave node is used to send a second signal to the master node. The signal flight time of the second signal to the master node is T2, and formula (2) is constructed as follows:

[0041] d= Formula (2);

[0042] The calculation unit is used to construct formula (3) based on the strength indication RSSI1 of the first signal.

[0043] d= Formula (3);

[0044] The calculation unit is used to construct formula (4) based on the strength indication RSSI2 of the second signal.

[0045] d= Formula (4);

[0046] Construct the first distance equation = Second distance equation = .

[0047] Preferably, the calculation unit is used to solve the following formula. Δt 1 ,Δt 2 ,

[0048] ,

[0049] Wherein, w1 and w2 are equal.

[0050] Preferably, the master node and slave node are Bluetooth Low Energy devices.

[0051] The present invention also discloses a vehicle including any of the Bluetooth ranging systems described above.

[0052] By adopting the above technical solution, compared with the prior art, the technical solution of the present invention can effectively combine two ranging methods, integrate and mutually correct the two measurement information, and improve the overall measurement accuracy of the ranging system; and no other hardware settings are required, which can be achieved by using existing Bluetooth devices, making it convenient and efficient. Attached Figure Description

[0053] Figure 1 Here is a flowchart of a Bluetooth ranging method in an embodiment of the present invention;

[0054] Figure 2 This is a schematic diagram of a Bluetooth ranging method in an embodiment of the present invention. Detailed Implementation

[0055] The advantages of the present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments.

[0056] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this disclosure as detailed in the appended claims.

[0057] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The singular forms “a,” “the,” and “the” as used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0058] In the following description, suffixes such as "module," "part," or "unit" used to denote elements are used only for the convenience of the description of the invention and have no specific meaning in themselves. Therefore, "module" and "part" can be used interchangeably.

[0059] Figure 1 The diagram shown is a flowchart of a Bluetooth ranging method according to one embodiment of the present invention. This embodiment specifically includes:

[0060] S1: The master node sends a first signal to the slave node. The signal flight time of the first signal to the slave node is T1, and the strength indication of the first signal is RSSI1.

[0061] S2: The slave node sends a second signal to the master node, the signal flight time of the second signal to the master node is T2, and the strength indication of the second signal is RSSI2;

[0062] S3:

[0063] Based on the flight time T1+ of the first signal Δt 1 With Intensity Indicator RSSI 1+ A 1 Construct a first distance equation for the first signal, based on the flight time T2+ of the second signal. Δt 2 With Intensity Indicator RSSI 2+ A 2 Construct a second distance equation for the second signal.

[0064] in Δt 1 and A 1 These are the measurement deviations of the signal flight time and intensity indication of the first signal, respectively. D t 2 and A 2 These are the measurement deviations of the signal flight time and intensity indication of the second signal, respectively;

[0065] When both the first distance calculation equation and the second distance calculation equation are satisfied, and the flight times of the first and second signals are equal, the solution can make... Get the minimum value Δt 1 ,Δt 2 , where w1 and w2 are the weight ratios and the sum of w1 and w2 is 1.

[0066] S4: Calculate the distance d according to the following formula:

[0067] d= , where C is the speed of light.

[0068] In this embodiment, the Bluetooth Low Energy (BLE) master node and slave node exchange carrier signals, such as... Figure 2 As shown. For the entire distance measurement time, In this embodiment, T1 is t2-t1, and T2 is t4-t3, representing the processing time of the slave node. In existing technologies, distance measurement is directly based on factors such as clock frequency deviation between the transmitting and receiving parties, antenna delay, and multipath propagation. Further consideration of measurement deviations is needed to make the ranging more accurate.

[0069] Simultaneously, ranging is performed based on RSSI: the first and second signals are modeled according to the following wireless signal propagation loss:

[0070]

[0071] in, and These represent the actual distance and the reference distance, respectively. and These represent RSSI at actual distance and reference distance, respectively. It is the path loss index. This is random noise. The larger the actual distance, the more... The greater the fluctuation of w, the smaller the fluctuation of w when the distance is closer. Therefore, when... If the distance is 1m, the distance measurement result can be approximately expressed as: , where A represents the signal strength indication received at a distance of 1 meter.

[0072] Therefore, based on the above testing methods, the following formulas (1)-(4) can be constructed:

[0073] d= Formula (1);

[0074] d= Formula (2);

[0075] d= Formula (3);

[0076] d= Formula (4).

[0077] Furthermore, since formulas (1) and (3) both represent the transmission distance of the first signal, and formulas (2) and (4) both represent the transmission distance of the second signal, the following equation can be derived:

[0078] =

[0079] = .

[0080] in, Δt 1 and A 1 These are the measurement deviations of the signal flight time and intensity indication of the first signal, respectively. D t 2 and A 2 , respectively, are the measurement deviations of the signal flight time and intensity indication of the second signal; A is the RSSI at a distance of 1 meter, and n is the path loss index.

[0081] Based on the above equation, construct the following formula and solve it. Δt 1 ,Δt 2 ,

[0082] .

[0083] Where w1 and w2 are weighting ratios, and the sum of w1 and w2 is 1. The values ​​of w1 and w2 are affected by the interference source. In a relatively stable environment, if the interference source remains unchanged, the values ​​of w1 and w2 are fixed. Typically, the default value of both w1 and w2 is 0.5. As mentioned earlier, the values ​​of w1 and w2 only need to be adjusted when there is prior knowledge. If the first signal is relatively reliable, the value of w1 can be increased, and the value of w2 can be decreased accordingly. In this embodiment, the values ​​of both w1 and w2 are 0.5. In another embodiment, w1 and w2 are 0.6 and 0.4, respectively.

[0084] Here, n is the path loss exponent. For the same transmission and reception distance, the path loss is also the same, so in a single measurement, the value of n is a constant. However, the specific value of n is affected by environmental factors. For example, in one embodiment of the present invention, the current environment is the suburbs, and the value of n is 6; in another embodiment, the current environment is the city, and the value of n is 4.

[0085] A represents the RSSI at a distance of 1 meter. The values ​​of A and n can be determined through prior measurement or experimentation under the same conditions.

[0086] The measurement deviation can be calculated using the above formula. Δt 1 ,Δt 2 Then, the distance between the master node and the slave node can be obtained by any of the formulas (1) to (4).

[0087] The present invention also includes an embodiment of a Bluetooth ranging system. In this embodiment, the Bluetooth ranging system includes a master node, a slave node, and a computing unit; the master node is used to send a first signal to the slave node, the signal flight time of the first signal to the slave node is T1, and the strength indication of the first signal is RSSI1;

[0088] The slave node is used to send a second signal to the master node, the signal flight time of the second signal to the master node is T2, and the strength indication of the second signal is RSSI2;

[0089] The calculation unit is used to solve the following formula. Δt 1 ,Δt 2 ,

[0090] ,

[0091] in, Δt 1 and A 1These are the measurement deviations of the signal flight time and intensity indication of the first signal, respectively. D t 2 and A 2 These are the measurement deviations of the signal flight time and intensity indication of the second signal, respectively; w1 and w2 are the weighting ratios, the sum of w1 and w2 is 1, A is the RSSI at a distance of 1 meter, and n is the path loss index;

[0092] The calculation unit is used to calculate the distance d according to the following formula:

[0093] d= , where C is the speed of light.

[0094] The technical features of the Bluetooth ranging system in this embodiment correspond to the technical features of the Bluetooth ranging method described above. Further details are omitted here.

[0095] In another embodiment, both the master node and the slave node are Bluetooth Low Energy devices, and the computing unit is an electronic chip integrated with the Bluetooth device. In other embodiments, the computing unit can be a computing module in a smart device, such as an MCU in a vehicle, with the specific form depending on the actual application.

[0096] Therefore, another embodiment of the present invention is a vehicle including the aforementioned Bluetooth ranging system. Using this Bluetooth ranging system, distance measurement can be performed using the vehicle's existing Bluetooth devices, such as measuring the distance between the vehicle key and the vehicle, thereby improving the accuracy of the ranging measurement and making the ranging function more stable.

[0097] In addition, the Bluetooth ranging system of this invention can be applied to distance estimation in one-way or two-way wireless communication scenarios. Furthermore, no additional hardware is required; the ranging method described above can be implemented using existing hardware.

[0098] In summary, the Bluetooth ranging method of this invention can effectively combine two ranging methods, integrate and mutually correct the two measurement information, and improve the overall measurement accuracy of the ranging system; moreover, it does not require any additional hardware settings and can be implemented using existing Bluetooth devices, making it convenient and efficient.

[0099] It should be noted that the embodiments of the present invention have better implementability and are not intended to limit the present invention in any way. Any person skilled in the art may use the above-disclosed technical content to change or modify it into equivalent effective embodiments. However, any modifications or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A Bluetooth ranging method, characterized in that, include: The master node sends a first signal to the slave node. The signal flight time of the first signal to the slave node is T1, and the strength indication of the first signal is RSSI1. The slave node sends a second signal to the master node, the signal flight time of the second signal to the master node is T2, and the strength indication of the second signal is RSSI2; Based on the flight time T1+ of the first signal Δt 1 With Intensity Indicator RSSI 1+ ΔA 1 Construct a first distance equation for the first signal, based on the flight time T2+ of the second signal. Δt 2 With Intensity Indicator RSSI 2+ ΔA 2 Construct a second distance equation for the second signal. in Δt 1 and ΔA 1 These are the measurement deviations of the signal flight time and intensity indication of the first signal, respectively. Δt 2 and ΔA 2 These are the measurement deviations of the signal flight time and intensity indication of the second signal, respectively; When both the first and second distance equations are satisfied, and the flight times of the first and second signals are equal, the solution can make... Get the minimum value Δt 1 Δt 2 , where w1 and w2 are the weight ratios and the sum of w1 and w2 is 1; Calculate the distance d using the following formula: d= Where C is the speed of light; Solve according to the following formula. Δt 1 Δt 2 , ， Where A is the RSSI of the signal at a distance of 1 meter, and n is the path loss exponent.

2. The Bluetooth ranging method as described in claim 1, characterized in that, The master node sends a first signal to the slave node. The signal flight time of the first signal to the slave node is T1. Formula (1) is constructed as follows: d= Formula (1); The slave node sends a second signal to the master node, and the signal flight time of the second signal to the master node is T2, thus constructing formula (2): d= Formula (2); The intensity indicator of the first signal is RSSI1, and formula (3) is constructed. d= Formula (3); The intensity indication of the second signal is RSSI2, and formula (4) is constructed. d= Formula (4); The first distance equation is = ; The second distance equation = .

3. The Bluetooth ranging method as described in any one of claims 1-2, characterized in that, w1 and w2 are equal.

4. A Bluetooth ranging system, characterized in that, Includes master nodes, slave nodes, and computing units; The master node is used to send a first signal to the slave node. The signal flight time of the first signal to the slave node is T1, and the strength indication of the first signal is RSSI1. The slave node is used to send a second signal to the master node, the signal flight time of the second signal to the master node is T2, and the strength indication of the second signal is RSSI2; The calculation unit is used to calculate based on the flight time T1+ of the first signal. Δt 1 With Intensity Indicator RSSI 1+ ΔA 1 Construct a first distance equation for the first signal, based on the flight time T2+ of the second signal. Δt 2 With Intensity Indicator RSSI 2+ ΔA 2 Construct a second distance equation for the second signal. in Δt 1 and ΔA 1 These are the measurement deviations of the signal flight time and intensity indication of the first signal, respectively. Δt 2 and ΔA 2 These are the measurement deviations of the signal flight time and intensity indication of the second signal, respectively; When both the first distance equation and the second distance equation are satisfied, and the flight times of the first and second signals are equal, the calculation unit is used to solve for the equation that enables... Get the minimum value Δt 1 Δt 2 , where w1 and w2 are the weight ratios and the sum of w1 and w2 is 1; The calculation unit is used to calculate the distance d according to the following formula: d= Where C is the speed of light; The calculation unit is used to solve the following formula. Δt 1 Δt 2 , ， Where A is the RSSI of the signal at a distance of 1 meter, and n is the path loss exponent.

5. The Bluetooth ranging system as described in claim 4, characterized in that, The master node sends a first signal to the slave node. The signal flight time of the first signal to the slave node is T1. Formula (1) is constructed as follows: d= Formula (1); The slave node sends a second signal to the master node, and the signal flight time of the second signal to the master node is T2, thus constructing formula (2): d= Formula (2); The calculation unit is used to construct formula (3) based on the strength indication RSSI1 of the first signal. d= Formula (3); The calculation unit is used to construct formula (4) based on the strength indication RSSI2 of the second signal. d= Formula (4); Construct the first distance equation = Second distance equation = .

6. The Bluetooth ranging system as described in claim 4, characterized in that, The calculation unit is used to solve the following formula. Δt 1 Δt 2 , ， Wherein, w1 and w2 are equal.

7. The Bluetooth ranging system as described in any one of claims 4-6, characterized in that, The master node and slave node are Bluetooth Low Energy devices.

8. A vehicle, characterized in that, Includes the Bluetooth ranging system as described in any one of claims 4-7.

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