A system for reducing UWB positioning error in a hydraulic support environment

Abstract

The application provides a hydraulic support environment UWB positioning error reduction system, belonging to the technical field of mine personnel positioning. The hydraulic support environment UWB positioning error reduction system comprises two or more groups of base station groups which are arranged in parallel on both sides of the hydraulic support and along a positioning tag movement path, the number of base stations in each group of base station groups is the same, and each group of base stations forms a positioning base station pair, further comprising a data processing terminal connected with all the base stations, the positioning tag simultaneously performs TOF positioning with all the base stations, and the data processing terminal determines the final positioning result of the positioning tag through the base station groups arranged along the positioning tag movement path. The hydraulic support environment UWB positioning error reduction system has the advantages of high positioning accuracy and reliable accuracy.

Description

Technical Field

[0001] This invention relates to the field of personnel positioning technology in mining, and more particularly to a system for reducing UWB positioning errors in hydraulic support environments. Background Technology

[0002] Most products on the market claim to achieve centimeter-level positioning accuracy, but in real-world applications, the results are vastly different. Positioning is affected by numerous factors, and theoretical values ​​from the laboratory cannot support practical limitations. To achieve the ideal state, besides focusing on deployment, the most important thing is a deep understanding of the application scenario. Factors affecting UWB (Ultra Wideband, a carrier-free communication technology that uses nanosecond to microsecond-level non-sinusoidal narrow pulses to transmit data) positioning include obstructions from metal objects, walls, refraction from glass and other objects, and environmental factors such as temperature and humidity.

[0003] like Figure 1 As shown, the space near the hydraulic support is almost entirely metallic with numerous obstacles. Furthermore, the positioning tag is worn on the waist, increasing the possibility of body obstruction. The environment is complex, exhibiting many NLOS (Non-Line of Sight, where the line of sight between two points is blocked, preventing them from seeing each other, and more than 50% of the Fresnel zone is obstructed) situations. It is significantly affected by multipath effects, such as... Figure 2 , 3 As shown. The main cause of multipath effect is that obstacles block the main path, and there are one or more strong reflecting paths. This can significantly affect positioning and thus positioning accuracy. Although positioning base stations themselves have a certain multipath discrimination capability, there is still a possibility of misjudgment in multi-metal environments.

[0004] In a hydraulic support environment, the multipath effect's impact on positioning varies depending on the specific conditions. In most cases, the positioning environment is ideal, making it relatively easy to distinguish between the primary and reflected signals (the primary signal is significantly stronger than the reflected signal), and the multipath effect has little impact. However, in a hydraulic support environment with numerous smooth metal surfaces, the signal is easily reflected through these surfaces. Furthermore, the human body has a strong absorption capacity for UWB signals, such as… Figure 3 As shown, if node A1 is a positioning tag, a human is an obstacle, and node A2 is a positioning base station, then in some cases the intensity of the reflected signal will be greater than the direct main signal. In this case, the main signal cannot be separated, and the accuracy of the positioning result will be reduced.

[0005] In practical applications, many factors can affect accuracy. To improve accuracy, it's necessary to control interference at its source. First, base stations should not be installed close to large areas of metal, and should be kept away from glass windows, glass walls, liquid containers, fluorescent lights, large machinery, high-power radio devices, etc. Antennas should be installed perpendicular to the ground. Second, the way tags are worn also has an impact. Because the human body has a strong absorption capacity for UWB signals, tags worn close to the chest will significantly affect accuracy. Third, multipath effects are difficult to eliminate. Electromagnetic waves are reflected by metals or other media during propagation, making multipath effects unavoidable. Therefore, this impact on accuracy can only be compensated for through post-processing of sampling and algorithms. Current technology lacks solutions for improving positioning accuracy in environments with numerous metal or hydraulic supports. Summary of the Invention

[0006] To address the problems in the prior art, this invention provides a system for reducing UWB positioning errors in hydraulic support environments.

[0007] The system for reducing UWB positioning errors in a hydraulic support environment according to the present invention includes two or more groups of base stations arranged parallel to both sides of the hydraulic support and along the movement path of the positioning tag. Each group of base stations has the same number of base stations, which form positioning base station pairs. It also includes a data processing terminal connected to each of the base stations. The positioning tag simultaneously performs Time-of-Flight (TOF) positioning with all the base stations. The data processing terminal determines the final positioning result of the positioning tag using the base station groups arranged along the positioning tag's movement path. The positioning method of the system for reducing UWB positioning error in the hydraulic support environment includes the following steps: S1: The positioning tag performs TOF positioning with all base stations simultaneously, and obtains the distance from the positioning tag to each base station. S2: Obtain the distance between each pair of base stations in the base station group; S3: Calculate the error value of the distance between base stations in the same base station group based on the data from steps S1 and S2; S4: Determine the line segment where the positioning tag is located based on the error value.

[0008] The present invention is further improved in that the number of base station groups is two, and the number of base stations in each base station group is more than two.

[0009] The present invention is further improved by the positioning method, which further includes step S5, a lateral judgment step: performing a lateral judgment based on the distance between the positioning tag and two base stations in the center of the base station pair to determine the base station group in which the positioning tag is located.

[0010] The present invention is further improved by the positioning method, which further includes step S6: based on all the judgment results of steps S5 and S6, the final judgment result is obtained, which is the positioning result of the positioning tag.

[0011] The present invention is further improved by including a calibration step before step S1 is executed, wherein each base station is calibrated and a calibration value is obtained, and the positioning result is calibrated based on the calibration value in steps S1-S4.

[0012] This invention is further improved in that, in step S1, the number of base stations in the base station group is 6, and the number of base station groups is 2. In one of the base station groups, the base stations are marked sequentially as S1, S2, S3, S4, S5, and S6 according to the movement path order, and their distances to the positioning tag are d1, d2, d3, d4, d5, and d6, respectively. Then, the error value in step S3 is calculated as follows: △ s1s6 =| d1+d6 - L s1s6 | Among them, L s1s6 This represents the actual distance between base stations S1 and S6. Similarly, the pairwise error Δ between the six base stations can be obtained. s2s5 , △ s3s4 ; Finally, the sum of errors for a group of base stations is obtained: Sum△ L =△ s3s4 +△ s2s5 +△ s1s6 .

[0013] In a further improvement to this invention, in step S4, the base station group with the smallest sum of errors is obtained, and the positioning tag is located on the mobile path of the base station group. Combined with the TOF positioning result, the final positioning result of the positioning tag is obtained.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention adopts TOF technology, uses multi-base station positioning, and communicates with positioning tags from multiple angles and in all directions, effectively overcoming the difficulty of signal interference in NLOS environment, and achieving high positioning accuracy and reliability; the present invention has strong fault tolerance, and can still locate normally even if one or two base stations fail; the system of the present invention deploys a certain number of base stations, which improves the anti-interference capability in complex environments. Attached Figure Description

[0015] Figure 1 A location environment diagram for the existing hydraulic support environment; Figure 2 This is a schematic diagram illustrating the reflection and refraction of signals through obstacles. Figure 3 This is a schematic diagram of the multipath effect; Figure 4 This is a schematic diagram of the system structure of the present invention; Figure 5 This is a flowchart of the method of the present invention; Figure 6 This is a schematic diagram for horizontal judgment. Detailed Implementation

[0016] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0017] like Figure 1 As shown, in a hydraulic support environment, the surroundings are all fixed metal, and the only passageway for personnel is a narrow alleyway, just wide enough for one person to pass through. The range of lateral movement is very limited; movement is restricted to forward and backward. Therefore, the personnel movement path can be considered a straight line. In a hydraulic support environment, multiple parallel alleyways are typically laid out for operation of the hydraulic support, with the metal fixed between two alleyways. The system for reducing UWB positioning errors in this hydraulic support environment includes several groups of base stations arranged parallel above the alleyways, with the same number of alleyways as the number of alleyways. Each group of base stations has the same number of base stations, forming positioning base station pairs. It also includes a data processing terminal connected to each of the base stations. The positioning tag simultaneously performs TOF positioning with all the base stations. The data processing terminal determines the final positioning result of the positioning tag by using the base station groups arranged along the positioning tag's movement path.

[0018] like Figure 4 As shown, as an embodiment of the present invention, the base station in this example ( Figure 1 The white box with an antenna and a data cable connected above the central alleyway (this is the base station) is installed overhead along the movement path to perform one-dimensional positioning with the positioning tag. In this example, two base station groups are set up, each with six base stations, for a total of 12 base stations. These base stations are sequentially labeled S1, S2, ..., S12 according to the movement path. Line segments S1S6 and S7S12 are also the movable positions of the positioning tag (hereinafter referred to as "Tag"). Of course, the number of base stations in this example can be adjusted as needed; two or more base station groups are sufficient for positioning.

[0019] Within the allowable error range (1 meter), it can be abstracted as a model of a point moving on a line segment. Therefore, the tag can be limited to either the left line segment S1S6 or the right line segment S7S. 12 The movement between the two line segments is significantly affected by the multipath effect, making it prone to misjudgment and impossible to accurately determine whether the positioning tag is on line segments S1-S6 or S7S. 12 To reduce the impact of multipath effects on positioning accuracy, we introduce a hydraulic environment personnel positioning method based on hydraulic support environment to reduce UWB positioning error.

[0020] like Figure 5 As shown, the positioning method in this example is processed by a data processing terminal connected to each base station, and specifically includes the following steps: S1: The positioning tag performs TOF positioning with all base stations simultaneously, and obtains the distance from the positioning tag to each base station. S2: Obtain the distance between any two base stations in the base station group; S3: Calculate the error value of the distance between adjacent base stations based on the data from steps S1 and S2; S4: Determine the line segment where the positioning tag is located based on the error value.

[0021] Preferably, the present invention may further include step S5, a lateral judgment step: performing a lateral judgment based on the distance between the positioning tag and two base stations in the base station pair to determine the base station group in which the positioning tag is located.

[0022] Preferably, the present invention further includes step S6: based on all the determination results of steps S5 and S6, a final determination result is obtained, which is the positioning result of the positioning tag.

[0023] The positioning method of the present invention will be described in detail below using this embodiment.

[0024] First, a preliminary judgment is made based on the base station location data of a single vertical base station group. The steps are as follows: 1. A tag can perform TOF positioning with up to 12 positioning base stations simultaneously, and the distances d1, d2, ..., d12 between the tag and each of the 12 base stations are calculated. 2. During installation, the base stations must be installed in the designated locations as required. Therefore, the coordinates of the 12 base stations are known, from which the length of each line segment can be determined, such as the length L of line segment S1S6. s1s6 And the length L of line segment S2S5 s2s5 ; 3. Calculate the error value based on the data from steps 1 and 2; Ideally, if the tag is on line segment S1S6, the distance from the tag to base station S1 plus the distance from the tag to base station S6 equals the length of line segment S1S6, that is... d1+d6 = L s1s6 There will inevitably be errors in reality, so we calculate the error value: △ s1s6 =| d1+d6 - L s1s6 | Similarly, we can obtain △ s2s5 , △ s3s4 , △ s7s12 , △ s8s11 , △ s9s10 , Calculate the sum of errors for the left and right base stations respectively. Sum△ L =△ s3s4 +△ s2s5 +△ s1s6 Similarly, we can obtain Sum△ R .

[0025] 4. The current line segment of the tag can be determined based on the sum of the error values.

[0026] If Sum△ L <Sum△ R If the error value of the tag is less on the left than on the right, then the tag can be determined to be on the left line segment S1S6; otherwise, it is on the right line segment S7S6. 12 superior.

[0027] The above calculation process assumes the location tag is in the middle S3S4 segment. If it is in S1S2 or S2S3 (the structure is symmetrical vertically; the algorithm is the same for S1S2 and S5S6, and similarly for S2S3 and S4S5), the error value is calculated as follows: When the tag is located in S2S3 or S4S5 △ s3s4 = | |d4-d3| - L s3s4 | Sum△ L =△ s3s4 +△ s2s5 +△ s1s6 When the tag is located at S1S2 or S5S6 △ s2s5 = | |d5-d2| - L s2s5 | △ s3s4 = | |d4-d3|- L s3s4 | Sum△ L =△ s3s4 +△ s2s5 +△ s1s6 The location of the tag can be determined by normal vertical judgment. However, for more accurate results, this example also adds a horizontal judgment step.

[0028] In this example, the horizontal determination is based on the fact that a left-side base station and a right-side base station, which are roughly the same vertical position, form a base station pair. S1 and S7 are one base station pair, S2 and S8 are another, and so on. Figure 4Taking the tag as an example, the distance from the tag to S1 calculated by the base station is d1, and the distance from the tag to S7 is d7. Since the signal needs to pass through the intermediate metal to reach S7, it is severely affected by multipath effects. The signal can only reach the base station after reflection. The path d7 that the signal takes is longer than the straight-line distance d from the tag to S7. TS7 Further away. Like... Figure 6 As shown, d TS7 Since the hypotenuse of a right triangle must be greater than d1, the calculated d7 reflects the reflection ratio d. TS7 It will be significantly larger than d1. If the above holds true, the base station determines that the tag for S1-S7 is on the left segment S1S6; otherwise, it determines it is on the right segment S7S6. 12 superior.

[0029] Similarly, the location of the tag (left or right) is determined by the base station pairs S2-S8, S3-S9, S4-S10, S5-S11 and S6-S12 respectively, and finally the determination results of the 6 base station pairs are counted.

[0030] After comparing the above vertical and horizontal data, using the positioning data of all base stations, seven judgment results are obtained. The position of the tag is voted on whether it is on the left or right. Finally, the voting results are compared, and the one with the most votes is the final judgment result, which is the final positioning result of the positioning tag. The final data processing terminal outputs this result.

[0031] In engineering applications, due to individual differences in hardware, different base stations (at the same location) may produce different positioning results for the same positioning tag. Therefore, this invention calibrates the base station during installation and records the calibration value on the system. The calibration value is then added when calculating the positioning result, which can further reduce positioning errors.

[0032] If the system detects that a base station is not working properly, then the left and right sides must be symmetrical during the calculation. For example, if the base station S1 on the left is not working properly, then the data of the base station S7 on the right will not be included in the calculation when performing the algorithm calculation. The same applies to other base stations.

[0033] In addition, when actually installing a base station, it is difficult to control the left and right sides of the base station to be in the same vertical position. There may be a difference of tens of centimeters due to the installation environment. In this case, the present invention also records this difference value in the system and takes this difference value into account as a correction factor when calculating the positioning result, so as to minimize the positioning error.

[0034] As can be seen from the above description, the present invention has the following innovative features: 1. This invention uses TOF technology and multi-base station positioning to communicate with positioning tags from multiple angles and in all directions, effectively overcoming the difficulty of signal interference in NLOS environments; 2. The algorithm uses error value calculation to make vertical judgments, then makes horizontal comparison judgments, and finally makes a comprehensive judgment on the location of the tag, which has higher stability and accuracy. 3. When making lateral judgments, the longer signal path affected by the multipath effect is used to determine which movement path the tag (signal source) is on. This invention has strong fault tolerance and can still locate the target even if one or two base stations fail. 4. By deploying a certain number of base stations according to the present invention, the anti-interference capability in complex environments is improved.

[0035] The specific embodiments described above are preferred embodiments of the present invention and are not intended to limit the specific scope of the present invention. The scope of the present invention includes, but is not limited to, these specific embodiments. All equivalent changes made in accordance with the present invention are within the protection scope of the present invention.

Claims

1. A system for reducing UWB positioning errors in a hydraulic support environment, characterized in that: The system includes two or more groups of base stations arranged parallel to each other on both sides of a hydraulic support and along the movement path of the positioning tag. Each group of base stations has the same number of base stations, forming a positioning base station pair. It also includes a data processing terminal connected to each of the base stations. The positioning tag simultaneously performs Time-of-Flight (TOF) positioning with all the base stations. The data processing terminal determines the final positioning result of the positioning tag using the base station groups arranged along the positioning tag's movement path. The positioning method of the system for reducing UWB positioning error in the hydraulic support environment includes the following steps: S1: The positioning tag performs TOF positioning with all base stations simultaneously, and obtains the distance from the positioning tag to each base station; S2: Obtain the distance between each pair of base stations in the base station group; S3: Calculate the error value of the distance between base stations in the same base station group based on the data from steps S1 and S2; S4: Determine the line segment where the positioning tag is located based on the error value.

2. The system for reducing UWB positioning error in a hydraulic support environment according to claim 1, characterized in that: The number of base station groups is two, and the number of base stations in each base station group is more than two.

3. The system for reducing UWB positioning error in a hydraulic support environment according to claim 1 or 2, characterized in that: The positioning method further includes step S5, a lateral judgment step: based on the distance between the positioning tag and two base stations in the center, a lateral judgment is made to determine the base station group in which the positioning tag is located.

4. The system for reducing UWB positioning error in a hydraulic support environment according to claim 3, characterized in that: The positioning method further includes step S6: based on all the judgment results of steps S5 and S6, the final judgment result is obtained, which is the positioning result of the positioning tag.

5. The system for reducing UWB positioning error in a hydraulic support environment according to claim 1 or 2, characterized in that: Before step S1 is executed, a calibration step is also included to calibrate each base station and obtain calibration values. In steps S1-S4, the positioning results are calibrated based on the calibration values.

6. The system for reducing UWB positioning error in a hydraulic support environment according to claim 5, characterized in that: In step S1, there are 6 base stations in the base station group and 2 base station groups. In one of the base station groups, the base stations are marked as S1, S2, S3, S4, S5, and S6 according to the movement path sequence, and their distances to the positioning tag are d1, d2, d3, d4, d5, and d6, respectively. Therefore, the error value in step S3 is calculated as follows: △ s1s6 =| d1+d6 - L s1s6 | Among them, L s1s6 This represents the actual distance between base stations S1 and S6. Similarly, the pairwise error Δ between the six base stations can be obtained. s2s5 , △ s3s4 ; Finally, the sum of errors for a group of base stations is obtained: Sum△ L =△ s3s4 +△ s2s5 +△ s1s6 .

7. The system for reducing UWB positioning error in a hydraulic support environment according to claim 6, characterized in that: In step S4, the base station group with the smallest sum of errors is obtained. The positioning tag is located on the mobile path of the base station group. Combined with the TOF positioning results, the final positioning result of the positioning tag is obtained.

Images