A method for improving Bluetooth positioning accuracy

Abstract

The present invention discloses a method for improving Bluetooth positioning accuracy. a. Construct a mobile terminal area scanning model, which is used to collect signal strength data and location data emitted by all Bluetooth beacons within the area. b. By combining the methods of rotating the area scanning position, expanding the area scanning range, and shrinking the area scanning range, find a set of Bluetooth beacons whose effective Bluetooth beacon density tends to 1 but is not equal to 1 as the effective Bluetooth beacon set, where the effective Bluetooth beacon density is equal to the ratio of the number of Bluetooth beacons with strong signal strength to the number of all Bluetooth beacons scanned within the area. c. Based on the location data of the Bluetooth beacons in the effective Bluetooth beacon set obtained in step b, the background server performs calculation and processing to obtain the positioning point of the mobile terminal. Bluetooth positioning is performed after more effective Bluetooth beacons can be obtained, improving the Bluetooth positioning accuracy, and a positioning accuracy within a diameter range of 1 - 3 meters can be achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of Bluetooth positioning, and relates to a method for improving Bluetooth positioning accuracy, in particular to a method for improving Bluetooth positioning accuracy by increasing the number of effective Bluetooth beacons. Background Art

[0002] As is well known, Bluetooth positioning technology relies on at least three Bluetooth beacons to simultaneously search for Bluetooth signals, and then uses the triangulation algorithm to locate the mobile terminal that emits the Bluetooth signal. The triangulation algorithm is just a basic model that can deduce the positions of the mobile terminal relative to the Bluetooth beacons placed at fixed positions, and then obtain the position of the mobile terminal. However, the current accuracy of Bluetooth positioning technology is mostly within a diameter range of 5 - 10 meters, which has little impact on relatively small areas. But in some places with large areas such as warehouses and factories, especially when there are many mechanical equipment, an error of 1 meter may very likely result in different movement trajectories, causing inaccurate positioning.

[0003] In addition, the basis for relatively higher positioning accuracy by using three Bluetooth beacons is that the signal strengths of these three Bluetooth beacons are good enough. Otherwise, even with more Bluetooth beacons, it is impossible to accurately locate the mobile terminal.

[0004] Furthermore, the existing Bluetooth positioning technology is generally applied indoors because it is convenient to deploy Bluetooth beacons. However, the positioning of mobile terminals is not limited to indoors, and in many scenarios, outdoor positioning is also required. Especially during the process of reciprocating between indoor and outdoor, switching the positioning mode will greatly affect the positioning accuracy and trajectory reproduction. Therefore, using only Bluetooth positioning to achieve simultaneous indoor and outdoor positioning is the best way. However, problems also arise. The narrowness of the indoor space and the difficulty of forming a neatly arranged dot matrix structure of Bluetooth beacons outdoors due to the open space outdoors both have a certain impact on the accuracy of Bluetooth positioning. Summary of the Invention

[0005] The purpose of the present invention is to improve the accuracy of Bluetooth positioning and avoid the technical problem of inaccurate positioning caused by poor signals received by Bluetooth beacons. A method for improving Bluetooth positioning accuracy is designed. By constructing a new Bluetooth beacon scanning model, more effective Bluetooth beacons are found, thereby achieving high-precision Bluetooth positioning.

[0006] The technical solution adopted by the present invention is a method for improving Bluetooth positioning accuracy. The method is implemented based on a system composed of fixedly arranged Bluetooth beacons and mobile terminals with Bluetooth positioning modules. The Bluetooth positioning module of the mobile terminal searches for data information sent by the Bluetooth beacons and sends it to the background server through the communication module for processing to achieve positioning. The key is that the method for improving Bluetooth positioning accuracy includes the following steps:

[0007] a. Construct a mobile terminal area scanning model, which is used to collect the signal strength data and location data sent by all Bluetooth beacons within the area;

[0008] b. Adopt a combination of rotating the area scanning position, expanding the area scanning range, and shrinking the area scanning range to find a set of Bluetooth beacons whose effective Bluetooth beacon density tends to 1 but is not equal to 1 as the effective Bluetooth beacon set. The effective Bluetooth beacon density is equal to the ratio of the number of Bluetooth beacons with strong signal strength to the number of all Bluetooth beacons scanned within the area;

[0009] c. Based on the location data of the Bluetooth beacons in the effective Bluetooth beacon set obtained in step b, the background server performs calculation and processing to obtain the positioning point of the mobile terminal.

[0010] The method further includes: d. Compensate the calculated positioning point data with an environmental attenuation factor, and the environmental attenuation factor is determined based on the actual situation of the site, according to the distance and signal strength value, in combination with the signal attenuation formula.

[0011] In step c, the triangulation method is used to calculate the positioning point of the mobile terminal.

[0012] After obtaining the positioning point of the mobile terminal, a positioning compensation process based on the predicted movement direction is performed. The specific steps are as follows:

[0013] 1). Establish a velocity model with a movement direction through two previously positioned positioning points. Connect the two previously positioned positioning points in a straight line, and the extension line of the straight line is used as the velocity direction. According to the velocity value of the mobile terminal in the velocity direction, the predicted positioning point of the mobile terminal is obtained at the next positioning time point;

[0014] 2). Neutralize and compensate the predicted positioning point in step 1) with the positioning point of the mobile terminal obtained by the background server in step c to obtain the final positioning point.

[0015] The velocity model in step 1) can be measured by gravitational acceleration or calculated through the distance and time between two points.

[0016] The neutralization and compensation process in step 2) is to connect the estimated positioning point and the positioning point of the mobile terminal obtained through the background server in a straight line, and take the center point as the final positioning point.

[0017] After at least two positioning compensation processes have been performed, the velocity model established in step 1) also performs angle compensation on the straight-line motion direction of the two previously positioned points through the Kalman filtering algorithm.

[0018] The method of angle compensation is to use the center line of the included angle formed by the boundary line of the Kalman filter and the straight line of the two positioned points as the final velocity direction.

[0019] The beneficial effects of the present invention are as follows.

[0020] 1. Bluetooth positioning is performed after more valid Bluetooth beacons can be obtained, which improves the accuracy of Bluetooth positioning and can achieve a positioning accuracy within a diameter range of 1 - 3 meters.

[0021] 2. If there are more than 3 valid Bluetooth beacons, position neutralization and compensation can be performed through multiple positionings, further improving the accuracy of Bluetooth positioning and can achieve a positioning accuracy within a diameter range of 1 - 1.5 meters.

[0022] 3. Combining positioning compensation based on the motion trajectory can effectively perform neutralization and compensation on the position estimated by the triangulation algorithm and the estimated position of the motion direction, improve the accuracy of Bluetooth positioning, and in the iterative process of continuous multi-point positioning, the compensation effect becomes better and better, and finally the positioning accuracy can be reduced to within a diameter range of 1 meter. Description of the Drawings

[0023] Figure 1 It is a schematic diagram of an embodiment of the area scanning model based on the layout of outdoor Bluetooth beacons in the present invention.

[0024] Figure 2 It is a schematic diagram of the principle of positioning compensation through motion direction estimation in the present invention. Detailed Embodiments

[0025] The following combines the drawings and specific embodiments to illustrate the specific working principle of the present invention.

[0026] The Bluetooth positioning in the present invention can be applied not only indoors but also outdoors. When applied indoors, the Bluetooth beacon is fixed on the wall, and when applied outdoors, it can be fixed on the ground through a fixed base.

[0027] In the specific implementation of the present invention, a mobile terminal regional scanning model is constructed, the purpose of which is to exclude Bluetooth beacons with weak signal strength in the surrounding area as much as possible when using Bluetooth positioning, because if the Bluetooth beacon signal is weak, a large deviation will occur during positioning. Therefore, a combination of rotating regional scanning positions, expanding the regional scanning range, and reducing the regional scanning range is adopted to find a group of Bluetooth beacons whose effective Bluetooth beacon density tends to 1 but is not equal to 1 as an effective Bluetooth beacon set, and the position data of the Bluetooth beacons in the above effective Bluetooth beacon set are used to calculate the positioning point of the mobile terminal.

[0028] For an example, see Figure 1 , the Bluetooth beacons set up outdoors will be arranged according to irregular areas such as grass and walking roads. Assuming that the mobile terminal is outdoors, it is first scanned with a circular model with a diameter of 8 meters, and 6 Bluetooth beacons are scanned, but the signal strength of 3 Bluetooth beacons is strong, while the signal strength of the remaining 3 Bluetooth beacons is weak due to the relatively long distance. At this time, the effective Bluetooth beacon density is 0.5, which is obviously low. Then the diameter of the circular model is reduced to 6 meters. At this time, only the previous 3 Bluetooth beacons with strong signals are scanned, and the effective Bluetooth beacon density at this time is 1. If in the prior art, the current positioning point can be directly obtained by the triangulation positioning algorithm, but the present application believes that the positioning point obtained in this way is not accurate enough. Therefore, the regional scanning model is changed again, and the regional scanning model is changed to a rectangular model with a length of 10 meters and a width of 5 meters, and then 5 Bluetooth beacons are scanned, 4 Bluetooth beacons with strong signals and 1 Bluetooth beacon with weak signals are obtained. The effective Bluetooth beacon density at this time is 0.8. Select 3 Bluetooth beacon data from 4 Bluetooth beacons with strong signals. There are three combinations in total. They are calculated by triangulation positioning algorithm to obtain 3 positioning points. Then the three positioning points are neutralized to obtain the final positioning position. Of course, more scanning models, such as ellipse, triangle, etc., can be used to expand or reduce the area, and multiple rounds of scanning can be performed. In short, the model with the effective Bluetooth beacon density closest to 1 is found. These models are pre-stored in the control unit of the mobile terminal. Each positioning point needs to be scanned sequentially through program control to determine the most suitable model for calculation. It should be emphasized that due to the irregular layout of outdoor Bluetooth beacons, it is not necessarily the case that the effective Bluetooth beacon density of the Bluetooth beacon set scanned by a certain area scanning model is necessarily closest to 1. Therefore, the software program is fixed, but it is necessary to compare in the end to find the Bluetooth beacon set with the effective Bluetooth beacon density closest to 1, and determine the data of this Bluetooth beacon set as the basic data of the triangulation positioning algorithm.

[0029] Considering the problem of the complexity of the surrounding environment, the compensation of the environmental attenuation factor is also considered when calculating the triangulation method. For example, indoor devices, machines or obstacles will block and interfere with the Bluetooth signal, which will inevitably have a certain impact on the data of the Bluetooth beacon. Therefore, it is adjusted with the environmental attenuation factor, further improving the positioning accuracy of indoor Bluetooth.

[0030] When positioning indoors, the principle is the same as above. However, in the control unit of the mobile terminal, the scanned area model is relatively fixed. Because the Bluetooth beacons in the indoor are relatively regularly arranged, but in principle, more valid Bluetooth beacon numbers need to be found first, and then positioning is carried out through the data of the valid Bluetooth beacons, and neutralization is carried out through various combinations.

[0031] To further improve the Bluetooth positioning accuracy and prevent signal drift, especially when the mobile terminal is moving, this solution estimates the movement direction. While calculating with the Bluetooth beacon data, the software of the control unit estimates the position of the next positioning point according to the movement direction, and neutralizes and compensates the position calculated by the estimated position and the Bluetooth beacon data. The reason is that in most cases, people are used to walking in a straight line. Even if they cannot walk completely straight, it is much better compared with the drift of Bluetooth positioning. The key point of this solution is to solve the problem of positioning point drift caused by unstable Bluetooth signals.

[0032] See Figure 2 , based on two previously positioned positioning points, the straight extension direction of these two points is the direction of the next estimated compensation point, and then the position of the final compensation point is estimated according to the calculated speed. This position is only the calculation basis point of the final positioning point. Connect the estimated compensation point and the positioning point obtained by the triangulation method, and its center point is used as the final positioning point after estimated compensation.

[0033] Of course, before the estimated compensation, the Kalman filtering algorithm can also be used to filter all the previous positioning points. The center line of the angle formed by the boundary line of the Kalman filter and the straight line of the two positioned points is used as the final speed direction. In this way, angle compensation can also be carried out for some points with large drift, making the final positioning point more accurate.

Claims

1. A method for improving Bluetooth positioning accuracy, which is implemented based on a system composed of fixedly installed Bluetooth beacons and mobile terminals with Bluetooth positioning modules. The Bluetooth positioning module of the mobile terminal searches for the data information sent by the Bluetooth beacons and sends it to the background server through the communication module for processing to achieve positioning. It is characterized in that: The method for improving Bluetooth positioning accuracy includes the following steps: a. Construct a mobile terminal area scanning model, which is used to collect the signal strength data and location data emitted by all Bluetooth beacons in the area; b. By combining the methods of rotating the area scanning position, expanding the area scanning range, and shrinking the area scanning range, find a set of Bluetooth beacons whose effective Bluetooth beacon density tends to 1 but is not equal to 1 as the effective Bluetooth beacon set, where the effective Bluetooth beacon density is equal to the ratio of the number of Bluetooth beacons with strong signal strength to the number of all Bluetooth beacons scanned in the area; c. Based on the location data of the Bluetooth beacons in the effective Bluetooth beacon set obtained in step b, the background server performs calculation and processing to obtain the positioning point of the mobile terminal.

2. The method for improving Bluetooth positioning accuracy according to claim 1, characterized in that: The method further includes: d. Compensate the calculated positioning point data with an environmental attenuation factor, and the environmental attenuation factor is determined according to the actual situation of the site, based on the distance and signal strength value, in combination with the signal attenuation formula.

3. The method for improving Bluetooth positioning accuracy according to claim 1, characterized in that: In step c, the triangulation method is used to calculate the positioning point of the mobile terminal.

4. The method for improving Bluetooth positioning accuracy according to claim 1, characterized in that: After obtaining the positioning point of the mobile terminal, a positioning compensation process based on motion direction prediction is performed. The specific steps are as follows: Establish a velocity model with a motion direction through two previously positioned positioning points. Connect the two previously positioned positioning points in a straight line, and the extension line of the straight line is used as the velocity direction. According to the velocity value of the mobile terminal in the velocity direction, obtain the predicted positioning compensation point of the mobile terminal at the next positioning time point.

5. The method for improving Bluetooth positioning accuracy according to claim 4, characterized in that: The velocity model is measured by gravitational acceleration or calculated through the distance and time between two points.

6. The method for improving Bluetooth positioning accuracy according to claim 4, characterized in that: The positioning compensation process is to connect the predicted positioning point and the positioning point of the mobile terminal obtained through the background server in a straight line, and take the center point as the final positioning point.

7. The method for improving Bluetooth positioning accuracy according to claim 4, characterized in that: After at least two positioning compensation processes, the velocity model established in step 1) also performs angle compensation on the straight-line motion direction of the two previously positioned points through the Kalman filter algorithm.

8. The method for improving Bluetooth positioning accuracy according to claim 7, characterized in that: The angle compensation method is to use the center line of the angle formed by the boundary line of the Kalman filter and the straight line of the two positioned points as the final velocity direction.

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