UWB-based planar positioning method, apparatus and system

Abstract

A UWB-based planar positioning method, apparatus and system, relating to the technical field of positioning in complex environments. On the basis of a second-order interlocked optimization mechanism using distances related to dual anchors and a heading angle for positioning error reduction, the method inputs known distances related to two anchors and a reliable heading angle of an electronic compass into a two-layer interlocked optimization model to obtain positioning coordinates, thus reducing NLOS interference, and improving the positioning precision.

Description

A UWB-based planar positioning method, apparatus, and system Technical Field

[0001] This invention relates to the field of positioning technology in complex environments, and in particular to a UWB-based planar positioning method, apparatus, and system. Background Technology

[0002] Existing positioning methods are applicable only in open, unobstructed environments. However, in complex environments with obstructions or interference, such as orchards, the dense canopies and branches of fruit trees can block radio signals from positioning systems like BeiDou and UWB, causing NLOS interference. This leads to unstable satellite signal reception and limits the application of mobile robots in orchards. Agricultural mobile robots cannot move autonomously due to the inability to obtain accurate location information. Therefore, there is an urgent need for a method to reduce NLOS interference and achieve more accurate positioning in complex environments such as orchards.

[0003] Summary of the Invention

[0004] This invention provides a UWB-based planar positioning method, apparatus, and system to reduce NLOS interference and achieve more accurate positioning in complex environments such as orchards.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] In a first aspect, the present invention provides a UWB-based planar positioning method, comprising:

[0007] S1: Perform one-dimensional Kalman filtering on the acquired first beacon ranging data and second beacon ranging data;

[0008] S2: Perform correction and compensation processing on the first and second beacon ranging data after one-dimensional Kalman filtering;

[0009] S3: The heading angle is obtained by using an electronic compass, and the corrected and compensated first beacon ranging data and second beacon ranging data, along with the heading angle, are input into the two-layer interlocking optimization model to obtain the positioning coordinates.

[0010] Secondly, this application provides a UWB-based planar positioning device, including at least four UWB positioning base stations, a first beacon, a second beacon, an electronic compass, and a controller. The base stations are located at the target location, and the first and second beacons are both placed parallel to the geomagnetic north direction. The controller is used to execute the steps of the method described in the first aspect above.

[0011] Thirdly, this application provides a UWB-based planar positioning system, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the method described in the first aspect above. Beneficial effects:

[0012] The UWB-based planar positioning method provided by this invention uses a second-order interlocking optimization positioning error reduction mechanism based on dual beacon distance and heading angle. By inputting the known distances of the two beacons and the reliable electronic compass heading angle into the two-layer interlocking optimization model, positioning coordinates can be obtained, which can reduce NLOS interference and improve positioning accuracy.

[0013] In a further scheme, based on the principle of multilateral positioning, the effective beacon positioning domain is constructed using ranging data from at least four base stations and beacons. Two-layer interlocking optimization processing of beacon distance and heading angle is carried out. After processing, the optimal positioning coordinates can be obtained. Attached Figure Description

[0014] Figure 1 is a flowchart of one of the preferred embodiments of the UWB-based planar positioning method of the present invention;

[0015] Figure 2 is a second flowchart of a UWB-based planar positioning method according to a preferred embodiment of the present invention;

[0016] Figure 3 is a flowchart of the two-layer interlocking optimization model of a preferred embodiment of the present invention;

[0017] Figure 4 is a schematic diagram of the polygonal positioning principle of a preferred embodiment of the present invention;

[0018] Figure 5 is a second schematic diagram of the polygonal positioning principle of a preferred embodiment of the present invention. Detailed Implementation

[0019] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms "an" or "a" and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms "connected" or "linked" and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up," "down," "left," "right," etc., are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship also changes accordingly.

[0021] Please refer to Figures 1-2. This application provides a UWB-based planar positioning method, including:

[0022] S1: Perform one-dimensional Kalman filtering on the acquired first beacon ranging data and second beacon ranging data;

[0023] S2: Perform correction and compensation processing on the first and second beacon ranging data after one-dimensional Kalman filtering;

[0024] S3: The heading angle is obtained by using an electronic compass, and the corrected and compensated first beacon ranging data and second beacon ranging data, along with the heading angle, are input into the two-layer interlocking optimization model to obtain the positioning coordinates.

[0025] The aforementioned UWB (Ultra Wide Band) based planar positioning method utilizes a second-order interlocking optimization positioning error reduction mechanism based on dual beacon distances and heading angles. By inputting the known distances of the two beacons and the reliable electronic compass heading angle into the two-layer interlocking optimization model, positioning coordinates can be obtained, thereby reducing NLOS interference and improving positioning accuracy.

[0026] The steps of the above-described UWB-based planar positioning method are described in detail below with a complete example:

[0027] First, the calibrated beacon-base station distance data is processed using a Kalman filter algorithm to perform initial filtering and reduce Gaussian noise. Based on this, and using the principle of multilateral positioning, the effective beacon positioning domain is constructed using ranging data from at least four base stations and the beacon. A two-layer interlocked optimization process of beacon distance and heading angle is then performed to obtain the optimal positioning coordinates.

[0028] The flowchart of the two-layer interlock optimization algorithm is shown in Figure 3.

[0029] It should be noted that, given the orchard environment, the actual distance measurement data is affected by non-line-of-sight interference such as trees, which leads to an increase in distance measurement error. The following steps are used to obtain the estimated positioning point.

[0030] First, the coordinate-heading angle is normalized. The base station is placed in an open area and its position is fixed. The base station coordinate system and the Beidou positioning coordinate system are normalized by using the differential Beidou positioning system and the northeast-sky coordinate system. As shown in Figure 4, after fixing the beacons T0, T1 and the electronic compass, T0 and T1 are placed parallel to the geomagnetic north direction. The current angle value β of the electronic compass is recorded. The eastward angle is defined as 0°. Then the normalized heading installation compensation angle β' is: β'=-β(1).

[0031] As shown in Figure 5, the landing areas of the two beacon positioning points are determined. The landing areas are obtained using the principle of polygon positioning, within the known base station coordinates.

[0032] A0(x0, y0), A1(x1, y1), A2(x2, y2), A3(x3, y3), the distance between tag T0 and the base station d0x, d 01 d 02 d 03 and the distance between tag T1 and the base station

[0033] d 10 d 11 d 12 d 13 Under the premise of [previous conditions], the landing area and corresponding intersection coordinates of the two label positioning coordinates are obtained by referring to the quadrilateral positioning principle. The polygon (with a maximum of four vertices) formed by the landing areas T0 and T1 is as follows:

[0034] Where S0(x, y) represents the landing area of ​​beacon T0, S1(x, y) represents the landing area of ​​beacon T1, and S... 0n (x 0n y 0n ) represents the coordinates of each vertex of the polygon corresponding to the landing point of beacon T0, S 1n (x 1n y 1n ) represents the coordinates of each vertex of the polygon corresponding to the landing point of beacon T1, and n represents the number of sides of the polygon.

[0035] Based on the Shoelace Theorem, the area S0 of the region where the coordinates of the first beacon fall and the area S1 of the region where the coordinates of the second beacon fall are obtained, satisfying the following relationship:

[0036] Comparing S0 and S1, the smaller area S is obtained. min S minThe corresponding landing point vertices satisfy the following relationship: S min (x, y) = S min_n (x min_n y min_n );

[0037] In the formula, x min_n S represents min The x-axis coordinates and y-axis coordinates of the corresponding landing point region vertices. min_n S represents min The y-axis coordinate of the corresponding landing point region vertex.

[0038] With a fixed distance L between two beacons and the detected heading angle α as constraints, the result is obtained based on S min Parallel projected coordinates S′ of (x, y) min (x, y) are as follows:

[0039] The intersection of the parallel-projected polygon and the larger-area polygon yields a new overlapping polygon. Based on this new overlapping polygon, the new vertex coordinates S of the polygon are determined. new (x, y):

[0040] In this embodiment, for S0 and S1, the smaller area is selected as Smin. After parallel projection of Smin, the overlapping polygon is obtained based on the intersection of the polygon obtained by parallel projection with the larger area of ​​S0 and S1.

[0041] Based on the new vertex coordinates S of the polygon new The centroid T is calculated from (x, y). new (x, y) satisfy the following relationship:

[0042] In the formula, The x-axis coordinates representing the centroid. The y-axis coordinate value represents the centroid.

[0043] Therefore, the positioning coordinates can be determined based on the centroid, satisfying the following relationship:

[0044] Through the above process, the optimal coordinate output is achieved by interlocking two layers of information input: normalized heading angle and fixed beacon distance.

[0045] This application also provides a UWB-based planar positioning device, including at least four UWB positioning base stations, a first beacon, a second beacon, an electronic compass, and a controller. The base stations are located at the target position, and the first and second beacons are both placed parallel to the geomagnetic north direction. The controller is used to execute the steps of the above-described method. This UWB-based planar positioning device can implement various embodiments of the above-described UWB-based planar positioning method and achieve the same beneficial effects.

[0046] This application also provides a UWB-based planar positioning system, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the above method.

[0047] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A UWB-based planar positioning method, characterized in that, include: S1: Perform one-dimensional Kalman filtering on the acquired first beacon ranging data and second beacon ranging data; S2: Perform correction and compensation processing on the first and second beacon ranging data after one-dimensional Kalman filtering; S3: The heading angle is obtained by using an electronic compass, and the corrected and compensated first beacon ranging data and second beacon ranging data, along with the heading angle, are input into the two-layer interlocking optimization model to obtain the positioning coordinates.

2. The UWB-based planar positioning method according to claim 1, characterized in that, Before step S1, the method further includes: Fix the first beacon T0, the second beacon T1, and the electronic compass. Position the first beacon T0 and the second beacon T1 parallel to the geomagnetic north direction. Record the current angle value β of the electronic compass. Define the eastward angle as 0°. Install the normalized heading compensation angle β'. β'＝-β(1)。 3. The UWB-based planar positioning method according to claim 1, characterized in that, S3 includes: The landing area of ​​the first beacon and the landing area of ​​the second beacon are obtained by using the principle of polygonal positioning, and the vertices of the polygon formed by the two landing areas are obtained. The smaller landing area S is determined based on the landing area of ​​the first beacon's location point and the landing area of ​​the second beacon's location point. min ; With the smaller area S min For reference, and constrained by the heading angle and the distance between the first and second beacons, the smaller area S is... min Perform parallel projection to obtain the new vertex coordinates of the polygon; Determine the centroid based on the new vertex coordinates of the polygon; The positioning coordinates are determined based on the centroid.

4. The UWB-based planar positioning method according to claim 3, characterized in that, The process of using the polygonal positioning principle to obtain the landing area of ​​the positioning point of the first beacon and the landing area of ​​the positioning point of the second beacon, and obtaining the vertices of the polygon formed by the two landing areas, includes: Determine the base station coordinates A0(x0, y0), A1(x1, y1), A2(x2, y2), A3(x3, y3), and the distance d between the first beacon T0 and the base station. 00 d 01 d 02 d 03 and the distance d between the second beacon T1 and the base station 10 d 11 d 12 d 13 ; Based on the principle of reference polygonal positioning, the landing area and corresponding intersection coordinates of the two beacon positioning coordinates are obtained. The vertices of the polygon formed by the landing areas of the first beacon T0 and the second beacon T1 satisfy the following relationship: Where S0(x, y) represents the landing area of ​​beacon T0, S1(x, y) represents the landing area of ​​beacon T1, and S... 0n (x 0n y 0n ) represents the coordinates of each vertex of the polygon corresponding to the landing point of beacon T0, S 1n (x 1n y 1n ) represents the coordinates of each vertex of the polygon corresponding to the landing point of beacon T1, and n represents the number of sides of the polygon.

5. The UWB-based planar positioning method according to claim 3, characterized in that, The smaller landing area S is determined based on the landing area of ​​the first beacon's positioning point and the landing area of ​​the second beacon's positioning point. min ,include: Obtain the area S0 of the region where the coordinates of the first beacon fall and the area S1 of the region where the coordinates of the second beacon fall, satisfying the following relationship: The smaller area S0 of the coordinate landing area of ​​the first beacon and the smaller area S1 of the coordinate landing area of ​​the second beacon is obtained. min S min The corresponding landing point vertices satisfy the following relationship: S min (x,y)=S min_n (x min_n ,y min_n ); Where x min_n S represents min The x-axis coordinates and y-axis coordinates of the corresponding landing point region vertices. min_n S represents min The y-axis coordinate of the corresponding landing point region vertex.

6. The UWB-based planar positioning method according to claim 3, characterized in that, The smaller area S min For reference, and constrained by the heading angle and the distance between the first and second beacons, the smaller area S is... min Performing parallel projection yields new vertex coordinates for the polygon, including: With a fixed distance L between two beacons and the detected heading angle α as constraints, the result is obtained based on S min Parallel projected coordinates S′ of (x, y) min (x, y) are as follows: The intersection of the parallel-projected polygon and the larger-area polygon yields a new overlapping polygon. Based on this new overlapping polygon, the new vertex coordinates S of the polygon are determined. new (x, y):

7. The UWB-based planar positioning method according to claim 3, characterized in that, Determining the centroid based on the new vertex coordinates of the polygon includes: Based on the new vertex coordinates S of the polygon new The centroid T is calculated from (x, y). new (x, y) satisfy the following relationship: In the formula, The x-axis coordinates representing the centroid. The y-axis coordinate value represents the centroid.

8. The UWB-based planar positioning method according to claim 3, characterized in that, The positioning coordinates determined based on the centroid satisfy the following relationship:

9. A UWB-based planar positioning device, characterized in that, The method includes at least four UWB positioning base stations, a first beacon, a second beacon, an electronic compass, and a controller. The base stations are located at the target location. The first beacon and the second beacon are both placed parallel to the geomagnetic north direction. The controller is used to perform the steps of the method described in any one of claims 1 to 8.

10. A UWB-based planar positioning system, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 8.

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