Anchor Node Distance Measurement and Positioning Method Based on Dual Distance Measurement Units

Abstract

This invention discloses an anchor node ranging and positioning method based on dual ranging units, belonging to the field of wireless positioning technology. The method involves deploying anchor nodes in the environment, each anchor node having two UWB ranging units. A host computer positioning system acquires the coordinate parameters of the anchor nodes, and the UWB ranging units obtain ranging information from the anchor nodes to an unknown node using UWB ranging methods. Then, a coordinate calculation method is used to convert the ranging information and the coordinates of the anchor nodes into the coordinates of the unknown node, thereby obtaining the coordinate information of the unknown node. This invention can reduce the complexity of anchor node deployment, reduce the number of anchor nodes deployed in the positioning system, and achieve the goal of sparse anchor node positioning.

Description

Technical Field

[0001] This invention relates to the field of wireless positioning technology, and in particular to an anchor node ranging and positioning method based on dual ranging units. Background Technology

[0002] A Wireless Networking Node (WSN) is a distributed, self-organizing network composed of three types of nodes: sensor nodes, aggregation nodes, and management nodes, capable of data acquisition, processing, and transmission. Positioning technology plays a crucial role as one of its key technologies. Current positioning technologies include ZigBee, Radio Frequency Identification (RFID), Bluetooth, WiFi, and Ultra-Wideband (UWB). Among these, UWB is a novel wireless carrier communication technology with strong resistance to multipath interference, high penetration, low power consumption, and high positioning accuracy, making it highly suitable for wireless positioning.

[0003] Existing positioning technologies require the deployment of a large number of anchor nodes for positioning. However, anchor nodes are nodes that need to be measured and installed manually. Deploying too many anchor nodes will increase labor costs and make the deployment of nodes more difficult. Deploying too few anchor nodes will not achieve positioning. Currently, each anchor node only has one UWB ranging unit, which can only obtain one ranging information and cannot adapt to environments with sparse anchor node deployment. Summary of the Invention

[0004] The purpose of this invention is to propose an anchor node ranging and positioning method based on dual ranging units. One anchor node is equipped with two UWB ranging units. The anchor node obtains two ranging information, or one ranging information and one azimuth information, by using the two UWB ranging units. The coordinates of the unknown node are then calculated, reducing the complexity of anchor node deployment, reducing the number of anchor nodes deployed in the positioning system, and achieving the goal of sparse anchor node positioning.

[0005] The technical solution adopted in this invention is as follows:

[0006] This invention relates to an anchor node ranging and positioning method based on dual ranging units. At least one anchor node is set in the environment, one of which has two UWB ranging units. The host computer positioning system obtains the coordinate parameters of the anchor node, and the UWB ranging units obtain the ranging information from the anchor node to the unknown node through the UWB ranging method. Then, the ranging information and the coordinates of the anchor node are converted into the coordinates of the unknown node through the coordinate calculation method, thereby obtaining the coordinate information of the unknown node.

[0007] Furthermore, the UWB ranging method uses a bilateral two-way ranging algorithm. This algorithm calculates the flight time using timestamps, and then multiplies the flight time by the speed of light to obtain the distance. The specific steps of the bilateral two-way ranging algorithm are as follows:

[0008] Step 1: The unknown node sends a POLL data packet to the anchor node;

[0009] Step 2: After receiving the POLL data packet from the unknown node, the anchor node returns a RESP data packet to the unknown node after a timed response.

[0010] Step 3: After receiving the RESP data packet sent by the anchor node, the unknown node responds within a time limit and then sends a Final data packet back to the anchor node.

[0011] Step 4: The anchor node receives the Final data packet sent by the unknown node;

[0012] The formula for calculating the data packet transmission time between the anchor node and the unknown node obtained by the bilateral two-way ranging algorithm is as follows:

[0013]

[0014] The distance between the anchor node and the unknown node is:

[0015] d=c* prop .

[0016] Furthermore, when there is one or two anchor nodes, and one of the anchor nodes has two UWB ranging units, the coordinate calculation method uses a two-point positioning method to calculate the coordinates of the unknown node.

[0017] Furthermore, the communication range extends outward from the center of the anchor node with two UWB ranging units, forming two communication ranges: a first communication range and a second communication range.

[0018] When an unknown node is within the first communication range of the anchor node, since the anchor node has two UWB ranging units, two ranging information can be obtained, and the coordinates of the unknown node can be calculated using a two-point positioning algorithm.

[0019] When an unknown node is within the second communication range of an anchor node, an ordinary anchor node is added. The ordinary anchor node has one UWB ranging unit, so the anchor node with two UWB ranging units obtains two ranging information. The one with the closer distance is selected to determine the azimuth information. Then, based on the ranging information of the ordinary anchor node, the coordinates of the unknown node can be calculated using a two-point positioning algorithm.

[0020] Furthermore, the two-point localization algorithm is specifically as follows:

[0021] Assuming the coordinates of the UWB ranging cells using the two-point positioning algorithm are (x1, y1) and (x2, y2), the coordinates of the unknown node are (x, y), and the distances from the unknown node to the UWB ranging cells are d1 and d2, then the distance equation system can be obtained as follows:

[0022]

[0023] Solving the above formula yields two coordinates. Then, the coordinates of the unknown node that do not meet the conditions are discarded, and the coordinates (x, y) of the unknown node can be obtained.

[0024] Furthermore, the anchor node includes a power supply circuit, a main control chip circuit, and a UWB signal transceiver circuit. The power supply circuit provides power to the anchor node. The main control chip circuit is connected to the UWB signal transceiver circuit via SPI communication and controls the UWB signal transceiver circuit to receive and send signals between the nodes. The signals acquired by the main control chip circuit are connected to the host computer via serial communication.

[0025] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0026] This invention relates to an anchor node ranging and positioning method based on dual ranging units. One anchor node is equipped with two UWB ranging units. The two UWB ranging units are used to obtain two ranging information or one ranging information and one orientation information through a UWB ranging algorithm. The coordinates of the unknown node are then calculated using a coordinate calculation method, thereby reducing the complexity of anchor node deployment and the number of anchor nodes deployed in the positioning system. This method is suitable for sparse anchor node positioning in underground roadway environments. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort, wherein:

[0028] Figure 1 This is a flowchart of the positioning calculation for anchor nodes and unknown nodes in Example 2;

[0029] Figure 2 This is a structural block diagram of the anchor node;

[0030] Figure 3 It is the process of data packet transmission between the anchor node and the unknown node;

[0031] Figure 4 This is a diagram showing the communication range of two UWB ranging unit anchor nodes;

[0032] Figure 5 It is a positioning diagram of an anchor node with two UWB ranging units;

[0033] Figure 6 This is a diagram showing the location of two anchor nodes. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments. The components of the embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0035] It should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0036] This invention relates to an anchor node ranging and positioning method based on dual ranging units. At least one anchor node is set in the environment, one of which has two UWB ranging units. The host computer positioning system obtains the coordinate parameters of the anchor node, and the UWB ranging units obtain the ranging information from the anchor node to the unknown node through the UWB ranging method. Then, the ranging information and the coordinates of the anchor node are converted into the coordinates of the unknown node through the coordinate calculation method, thereby obtaining the coordinate information of the unknown node.

[0037] like Figure 2 As shown, the anchor node includes a power supply circuit, a main control chip circuit, and a UWB signal transceiver circuit. The power supply circuit provides power to the anchor node. The main control chip circuit is connected to the UWB signal transceiver circuit via SPI communication and controls the UWB signal transceiver circuit to receive and send signals between the nodes. The signals acquired by the main control chip circuit are connected to the host computer via serial communication.

[0038] Example 1

[0039] When there is one anchor node with two UWB ranging units, the anchor node has two communication ranges, namely a first communication range and a second communication range, radiating outwards from the center of the anchor node with two UWB ranging units. For example... Figure 4 As shown, Figure 4The anchor node is divided into two communication ranges: the area within the solid circle is the first communication range, and the area outside the solid circle but within the dashed circle is the second communication range. In the diagram, the ellipse represents an anchor node with two UWB ranging units, the two circles labeled 1 and 2 are the two UWB ranging units, and the number 3 refers to the anchor node. The distance between 1 and 2 is called the communication arm length. Within the first communication range, the anchor node can obtain two ranging information values; within the second communication range, the anchor node can obtain one ranging information value and one orientation information value. This orientation information determines whether the tag node is to the left or right of the dashed line. The side where the UWB ranging unit obtains a smaller distance indicates which side of the dashed line the unknown node is on.

[0040] However, the environment of underground roadways is quite unique, making it unsuitable to install too many anchor nodes due to installation difficulties and high costs. Figure 5 As shown, when an unknown node is within the first communication range of the anchor node, since the anchor node has two UWB ranging units, two ranging information can be obtained, and the coordinates of the unknown node can be calculated using a two-point positioning algorithm.

[0041] The UWB ranging unit uses the UWB ranging method to obtain ranging information, specifically:

[0042] The UWB ranging method uses a bilateral two-way ranging algorithm. This algorithm calculates the flight time using timestamps, and then multiplies the flight time by the speed of light to obtain the distance. The specific steps of the bilateral two-way ranging algorithm are as follows:

[0043] Step 1: The unknown node sends a POLL data packet to the anchor node;

[0044] Step 2: After receiving the POLL data packet from the unknown node, the anchor node returns a RESP data packet to the unknown node after a timed response.

[0045] Step 3: After receiving the RESP data packet sent by the anchor node, the unknown node responds within a time limit and then sends a Final data packet back to the anchor node.

[0046] Step 4: The anchor node receives the Final data packet sent by the unknown node;

[0047] The formula for calculating the data packet transmission time between the anchor node and the unknown node obtained by the bilateral two-way ranging algorithm is as follows:

[0048]

[0049] The distance between the anchor node and the unknown node is:

[0050] d=c*T prop .

[0051] The bilateral two-way ranging algorithm uses two round-trip times to calculate the flight time, which can reduce errors and solve the problem of synchronization between the anchor node and the unknown node. The data packet transmission process between the anchor node and the unknown node is as follows: Figure 3 As shown.

[0052] The two-point localization algorithm is specifically as follows:

[0053] Assuming the coordinates of the UWB ranging cells using the two-point positioning algorithm are (x1, y1) and (x2, y2), the coordinates of the unknown node are (x, y), and the distances from the unknown node to the UWB ranging cells are d1 and d2, then the distance equation system can be obtained as follows:

[0054]

[0055] Solving the above formula yields two coordinates. Then, the coordinates of the unknown node that do not meet the conditions are discarded, and the coordinates (x, y) of the unknown node can be obtained.

[0056] Example 2

[0057] The difference between this embodiment and Embodiment 1 is that:

[0058] When the unknown node is relatively far from the anchor node, i.e., within the second communication range of the two UWB ranging unit anchor nodes, it is necessary to add another ordinary anchor node, such as... Figure 6 As shown, a regular anchor node has one UWB ranging unit, while an anchor node with two UWB ranging units obtains two ranging information points. The closer ranging information is selected to determine the azimuth information. Then, based on the ranging information from the regular anchor node, the coordinates of the unknown node can be calculated using a two-point positioning algorithm. The structural diagram for calculating the coordinates of an unknown node using two anchor nodes is shown below. Figure 1 As shown in the figure. The specific steps for the UWB ranging unit to obtain ranging information using the UWB ranging method, and the specific steps for the two-point positioning algorithm to obtain the coordinates of unknown nodes, are as described in Embodiment 1 above.

[0059] One of the anchor nodes in this invention is equipped with two UWB ranging units. The two UWB ranging units are used to obtain two ranging information or one ranging information and one orientation information through the UWB ranging algorithm. The coordinates of the unknown node are then calculated through a two-point positioning algorithm, thereby reducing the complexity of anchor node deployment and reducing the number of anchor nodes deployed in the positioning system. This invention is suitable for sparse anchor node positioning in underground roadway environments.

[0060] In environments with a large number of anchor nodes, more ranging information can be obtained, and the maximum likelihood localization algorithm can be used, which can utilize more ranging information to make the localization more accurate.

[0061] The specific method for obtaining the coordinates of an unknown node using multiple ranging data is as follows:

[0062] Given an unknown node with coordinates (x, y), and n anchor nodes within its location range with coordinates (x1, y1), (x2, y2), (x3, y3), ..., (x4, y4) n ,y n Let the distances from the unknown node to these n anchor nodes be d1, d2, d3... ...2, d3, d4, d5, d6, d7, d8, d9, d1, d2, d3, ..., d4, respectively. n Then we can obtain the following formula:

[0063]

[0064] The above equation can be transformed into a system of linear equations AX = b, where:

[0065]

[0066]

[0067]

[0068] The coordinates of the unknown node to be located can then be calculated using the standard least mean square error estimation method:

[0069]

[0070] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be conceived by those skilled in the art within the technical scope disclosed in the present invention without creative effort should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A ranging positioning method based on dual ranging unit anchor node, at least one anchor node is set in the environment, characterized in that: One of the anchor nodes has two UWB ranging units, the upper computer positioning system obtains the coordinate parameters of the anchor nodes, and the UWB ranging unit obtains the ranging information from the anchor nodes to the unknown node through the UWB ranging method, and then the ranging information and the coordinates of the anchor nodes are converted into the coordinates of the unknown node through the coordinate calculation method, so as to obtain the coordinate information of the unknown node; The UWB ranging method uses a double-side two-way ranging algorithm, which calculates the time of flight through a timestamp, and then multiplies the time of flight by the speed of light to obtain the distance. The steps of the double-side two-way ranging algorithm are as follows: Step 1: the unknown node sends a POLL data packet to the anchor node; Step 2: after receiving the POLL data packet sent by the unknown node, the anchor node returns a RESP data packet to the unknown node after a time response; Step 3: after receiving the RESP data packet sent by the anchor node, the unknown node returns a Final data packet to the anchor node after a time response; Step 4: the anchor node receives the Final data packet sent by the unknown node; The calculation formula of the data packet transmission time between the anchor node and the unknown node obtained by the double-side two-way ranging algorithm is as follows: ， The distance between the anchor node and the unknown node is: d= ； When there is one or two anchor nodes, and one of the anchor nodes has two UWB ranging units, the coordinate calculation method uses a two-point positioning method to calculate the coordinates of the unknown node; The anchor node with two UWB ranging units is taken as the center of a circle and diffuses outward, and the anchor node has two communication ranges, namely a first communication range and a second communication range, When the unknown node is in the first communication range of the anchor node, since the anchor node has two UWB ranging units, two ranging information can be obtained, and the coordinates of the unknown node can be calculated by using a two-point positioning algorithm; When the unknown node is in the second communication range of the anchor node, an ordinary anchor node is added, the ordinary anchor node has one UWB ranging unit, the anchor node with two UWB ranging units obtains two ranging information, selects one ranging information with a short distance, determines the orientation information, and then according to the ranging information of the ordinary anchor node, the coordinates of the unknown node can be calculated by using a two-point positioning algorithm.

2. The dual-TOA unit based anchor node ranging positioning method of claim 1, wherein, The two-point positioning algorithm is as follows: Assume that the coordinates of the UWB ranging unit using two-point positioning algorithm are , , the unknown node coordinates are , and the distance from the unknown node to the UWB ranging unit is , , then the distance equation group can obtain the following formula: Solving the above equation gives two coordinates, and then the unknown node coordinates that do not meet the conditions are discarded, and the coordinates of the unknown nodes are obtained .

3. The dual-TOA unit based anchor node ranging positioning method of claim 1, wherein, The anchor node includes a power supply circuit, a main control chip circuit and a UWB signal transceiver circuit, the power supply circuit is used to provide power supply for the anchor node, the main control chip circuit is in SPI communication connection with the UWB signal transceiver circuit, and the UWB signal transceiver circuit is used to receive and send signals between nodes, and the signals obtained by the main control chip circuit are connected with the upper computer through serial communication.

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