CN113490145B

CN113490145B - Ad hoc network positioning system based on UWB

Info

Publication number: CN113490145B
Application number: CN202110869412.9A
Authority: CN
Inventors: 杨永辉; 谢晓博; 刘宏罡; 杨艳秋; 彭华洋
Original assignee: V Power Information Technology Co ltd
Current assignee: V Power Information Technology Co ltd
Priority date: 2021-07-30
Filing date: 2021-07-30
Publication date: 2022-06-17
Anticipated expiration: 2041-07-30
Also published as: CN113490145A

Abstract

The invention discloses an ad hoc network positioning system based on UWB, which comprises a long-distance Bluetooth gateway or a UWB base station, 1 or a plurality of fixed-point tags, 1 or a plurality of nearby tags and a server. The invention adopts a mechanism combining UWB and Bluetooth, and coordinates the master-slave relation M and the fixed point relation A of the label while reducing the power consumption, and confirms the self-positioning condition F; meanwhile, the ranging result is uploaded through Bluetooth, so that the ranging result can be conveniently received by a Bluetooth gateway or other intelligent equipment such as a tablet, a mobile phone and the like with Bluetooth, and the position information is further analyzed and displayed on a map; and self positioning and navigation can be realized. The firefighter carrying the tag can acquire the position information of the member carrying the tag at any time through the industrial tablet, and can support teammates through navigation or arrange personnel nearby for support. Because the data is directly transmitted from the tag to the tablet personal computer or the smart phone, the data does not need to be forwarded through a cloud platform or a server and the like, and the time delay of the position data is reduced to the minimum.

Description

Self-networking positioning system based on UWB

Technical Field

The invention relates to the technical field of positioning, in particular to an ad hoc network positioning system based on UWB.

Background

As the last kilometer of GPS positioning, the application market of indoor wireless positioning is also increasingly widespread along with the wide application of GPS positioning. Currently, the positioning technologies mainly include bluetooth RSSI (reference signal strength) positioning, bluetooth AOA/AOD (angle of arrival/angle of transmission) positioning, WIFI positioning, LBS (mobile location service) and UWB (ultra wide band) positioning. In which UWB positioning is based on centimeter-level accuracy and is ranked on indoor positioning accuracy.

The existing UWB positioning generally adopts a fixed base station manner to collect broadcast data of a tag, and calculates the location of the tag through time of arrival (TOA) or Time Difference (TDOA). In these methods, base stations need to be laid out in advance, and each base station needs to be connected to a server through a network to be normally positioned.

Disclosure of Invention

In view of the above, the present invention is directed to an ad hoc network positioning system based on UWB, which has a simple structure, is convenient to install, and is accurate in positioning.

In order to achieve the purpose, the invention provides the following technical scheme:

an UWB-based ad-hoc network positioning system, the system comprising: a remote Bluetooth gateway or UWB base station, 1 or more fixed point tags, 1 or more nearby tags and a server; the remote Bluetooth gateway or the UWB base station, 1 or more tags and the server form an ad hoc network positioning system; wherein,

the remote Bluetooth gateway or the UWB base station acquires coordinate data of the remote Bluetooth gateway or the UWB base station through a high-precision positioning module;

each fixed point tag can perform bidirectional ranging with nearby tags and upload ranging information to a long-distance Bluetooth gateway or a UWB base station in a broadcasting mode;

the server is used for collecting and recording label confidence and positioning the label.

Preferably, in the above-mentioned an ad hoc network positioning system based on UWB, the system further comprises a TWR positioning system, said TWR positioning system is configured to determine a coordinate node (xi, yi) (i ═ 1, 2.. n) of said fixed point tag; the coordinate node is known as a coordinate node.

Preferably, in the UWB-based ad hoc network positioning system, the unknown coordinate nodes (x, y) are calculated from the known coordinate nodes.

Preferably, in the above-mentioned ad hoc network positioning system based on UWB, the position coordinates of the fixed point tag are known or the coordinates relative to the UWB base station are known, and the UWB base station has a high-precision positioning module for calculating the coordinates of the fixed point tag.

Preferably, in the above-mentioned UWB-based ad hoc network positioning system, the high-precision positioning module determines a known number of coordinate nodes n measured by the tag, where the known number of coordinate nodes is three cases, n ≧ 3, n ═ 2, and n ═ 1.

Preferably, in the ad hoc network positioning system based on the UWB, all fixed-point tags operate in one frequency band, and a plurality of tags have same frequency interference, and a master-slave relationship of tag ranging needs to be dynamically coordinated, so that the same frequency band interference is avoided; after the tags are initialized, all tags work in a UWB base station receiving mode by default, Bluetooth broadcasting and scanning are started, 500ms broadcasting is performed by default once, and broadcast information comprises an ID, a master-slave relation zone bit M, a fixed point tag zone bit A and a quasi-fixed point tag zone bit F.

Preferably, in the above UWB based ad hoc network positioning system, the TWR positioning system comprises a module a and a module B; each module generates an independent time stamp from the start; the transmitter of said module a transmits a pulse signal of the requested nature at Tsp on its time stamp, module B transmits a signal of the responsive nature at the time of TSR, is received by module a at its own time stamp TRR, and then transmits a signal to be received by module B at the TRF; calculating the flight time T of the pulse signal between the two modules according to the two data to determine the flight distance r, and the flight time T to determine the flight distance r can be expressed as the following formula:

T＝(2TRR-TSP-2TSP+TRP+TRF-TSF)/4；

r ═ T × C; where C is the speed of light.

According to the technical scheme, compared with the prior art, the invention has the following characteristics:

1. the dependence on UWB multiple base stations is reduced;

2. positioning of the label and the base station in a mobile scene is realized;

3. optimizing positioning precision and reducing position delay;

4. and the positioning cost of the UWB unit area is reduced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the prior art descriptions will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a schematic diagram of the present invention.

Fig. 2 is a schematic diagram of the structure of the fixed-point tag of the present invention, which is 3.

Fig. 3 is a schematic structural diagram of 2 fixed-point tags according to the present invention.

Fig. 4 is a schematic structural diagram of the fixed-point tag of the present invention, which is 1.

FIG. 5 is a graph showing a substantially normal distribution of the statistics and distances according to the present invention.

Fig. 6 is a UWB system framework diagram of embodiment 1 of the present invention.

Fig. 7 is a block diagram of an autonomous tag positioning system according to embodiment 1 of the present invention.

Fig. 8 is a system framework diagram of embodiment 2 of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, an ad hoc network positioning system based on UWB disclosed in the present invention specifically includes:

a remote Bluetooth gateway or UWB base station, 1 or more fixed point tags, 1 or more nearby tags and a server; the remote Bluetooth gateway or the UWB base station, 1 or more tags and the server form an ad hoc network positioning system; wherein,

the server is used for collecting and recording the label confidence and positioning the label.

In order to further optimize the above technical solution, the system further includes a TWR positioning system, wherein the TWR positioning system is configured to determine a coordinate node (xi, yi) (i ═ 1, 2.. n) of the fixed-point tag; the coordinate node is known as a coordinate node.

In order to further optimize the technical scheme, the unknown coordinate nodes (x, y) are calculated according to the known coordinate nodes.

In order to further optimize the technical scheme, the fixed point tag has known position coordinates or known coordinates relative to the UWB base station, and the UWB base station is provided with a high-precision positioning module for calculating the coordinates of the fixed point tag.

In order to further optimize the technical scheme, the high-precision positioning module judges the known coordinate node number n measured by the label, wherein the known coordinate node number is divided into three cases, namely n is more than or equal to 3, n is 2 and n is 1.

In order to further optimize the technical scheme, all fixed-point tags work in one frequency band, the same frequency interference exists in a plurality of tags, and the master-slave relation of tag ranging needs to be dynamically coordinated, so that the interference of the same frequency band is avoided; after the tags are initialized, all tags work in a UWB base station receiving mode by default, Bluetooth broadcasting and scanning are started, 500ms broadcasting is performed by default once, and broadcast information comprises an ID, a master-slave relation zone bit M, a fixed point tag zone bit A and a quasi-fixed point tag zone bit F.

In order to further optimize the technical scheme, the TWR positioning system comprises a module A and a module B; each module generates an independent time stamp from the start; the transmitter of said module a transmits a pulse signal of the requested nature at Tsp on its time stamp, module B transmits a signal of the responsive nature at the time of TSR, is received by module a at its own time stamp TRR, and then transmits a signal to be received by module B at the TRF; calculating the flight time T of the pulse signal between the two modules according to the two data to determine the flight distance r, and the flight time T to determine the flight distance r can be expressed as the following formula:

T＝(2TRR-TSP-2TSP+TRP+TRF-TSF)/4；

r ═ T × C; wherein C is the speed of light;

the ranging scheme based on the DW1000 scheme PDOA algorithm is as follows, in order to realize the angle estimation of tag, two identical antennas with the interval d < lambda/2 are arranged on the UWB base station, and the phase difference of a certain signal on the tag reaching the two antennas is in the range of-180 degrees to 180 degrees. The measured phase difference (Δ Φ) is converted into a distance difference (P ═ λ × Δ Φ/(2 pi)), and the distance r is obtained from the time of flight, as follows from the system of equations of geometric relationships:

r^2＝x^2+y^2；(x-d)^2+y^2＝(r-p)^2

and finally, obtaining the positioning coordinate data (x, y) of the tag label.

In order to realize the conversion from the relative position to the absolute position, a beidou high-precision positioning module is usually installed in a positioning base station, and 3 known coordinates are installed, or a fixed-point tag relative to the known coordinates of the base station is used as a position initialization reference:

ad hoc network positioning principle:

A. the position coordinates of the fixed point tags are known, or the coordinates relative to the base station are known, and the base station is provided with a high-precision Beidou positioning module which can calculate the coordinates of the fixed point tags;

B. measuring the distance between the surrounding labels and the fixed point labels, if the distance between the label and 3 fixed point labels is measured at the same time, drawing three circles according to the distance, wherein the intersection point is the coordinate of the label, and the label is converted into a quasi fixed point label (the position is known);

C. if a certain positioning label and any 3 fixed point labels or quasi-fixed point labels measure distances, the coordinates can be calculated in the mode B and converted into quasi-fixed point coordinates;

D. if there are tags in individual edge zones, and there are only 2 surrounding pinpoint or quasi-pinpoint tags, then the tag can calculate two coordinates from the intersection of two circles, where one coordinate is close to the other quasi-pinpoint tag (lower graph positioning tag 2) and the other is far from the other tag (lower graph positioning tag 2'). Because the positioning label 2' close to one side can theoretically measure the distance with other labels, and can not measure the distance only when the positioning label is far away (except the condition that the label is shielded), the outer side coordinate far away from other labels is taken as a theoretical coordinate, the platform uses special colors to distinguish the two coordinate points, and the coordinate is marked;

E. if a certain label can only measure the distance with one label, the position of the label can be displayed on an arc drawn by the distance measured by the label, and the start point and the end point of the arc are positioned on the extension lines of other (quasi) fixed point labels and the quasi fixed point label 3 and the rubber pad of the circle;

restoring the fixed point until other tags can measure the distance;

F. when a single label cannot measure the distance with other labels, the position display keeps the last record and is specially marked.

Label bidirectional ranging dynamic coordination ad hoc network technology

Considering that UWB tags all work in a frequency band, co-channel interference may exist in multiple tags, and therefore a master-slave relationship of tag ranging needs to be dynamically coordinated, the working mechanism is as follows:

1. after all the tags are initialized, all the tags work in a UWB receiving mode by default, Bluetooth broadcasting and scanning are started, broadcasting is performed for 500ms by default once, and broadcasting information comprises one-dimensional forwarding times marking bits (N) and (UWB) ID, a master-slave relation marking bit (M), a fixed point tag marking bit (A) and a quasi-fixed point tag marking bit (F); wherein, N is 0 to represent the original ranging packet, and N is another integer value to represent the forwarding times of the ranging packet; the Reserve data comprises data such as a distance measurement distance, tag IDs of both distance measurement parties and the like, and is not disclosed; the master-slave relationship flag bit is used for confirming who initiates a ranging request, all fixed-point tags are used as masters under the default condition (M is 1), and the other tags are used as slaves under the initial condition (M is 0); the quasi-fixed point tag flag bit F is used for distinguishing whether the tag can determine its own coordinate through ranging, an initial value F is 0, which indicates that no positioning is performed, and subsequently, as the ranging is performed, the value F is modified, F is 1 single-tag positioning, F is 2 double-tag positioning, F is 3 multi-tag positioning, and F is 3 fixed point tag positioning, which indicates that multiple tags are positioned. The broadcast format is as follows:

2. all the Bluetooth parts of the tags scan surrounding tags in the rest non-broadcast time, record various flag bits, IDs (identity) and RSSI (received signal strength indicator) information of the surrounding tags, and update the time once at T0(T0 is a data update period, such as 3 s);

3. the fixed point tag defaults to be dominant (M is 1), a quasi-fixed point tag flag bit F is 3, a ranging request is initiated after a random delay function based on UWB ID as an initial value is used, request information comprises ID information of non-fixed point tags, if a certain fixed point tag receives ranging requests of other tags in a delay period, the fixed point tag continues to be started to receive and refreshes the random delay function, and if no UWB data packet is received after the delay is finished, the ranging request is initiated; polling all ID tags by the fixed point tag, if a tag fails in ranging, arranging the tag to the last, and if the polling is finished or the ranging period T1 is overtime, finishing ranging in one period;

4. the non-fixed point tag defaults to be a slave, if the scanned data does not have a master-slave relation zone bit according to the information scanned by the Bluetooth, the non-fixed point tag modifies the non-fixed point tag to be a master, and sends a UWB ranging request after random delay by taking the ID of the non-fixed point tag as an initial value, and if the non-fixed point tag receives other ranging requests indirectly in a delay period, the non-fixed point tag is continuously opened to receive and refresh delay time; and then polling all the ID tags, if the tags failing in ranging are found, arranging the tags to the end until the polling is finished or the ranging period is overtime, and finishing the ranging of one period.

5. After the non-fixed point tag finishes ranging in one period, counting the total number N of F-3 in the tags with successful ranging, if N is greater than 2, modifying the self-fixed point tag flag bit F-3, if N is 2, F-2, if N is 2, F-N; the fixed point tag does not make this determination, and F ═ 3 is always true.

6. After the F value is refreshed, all the ranging main tags M are 1, and the ranging results are broadcasted by using the Bluetooth, and as ranging is finished in a time-sharing and alternate mode, the Bluetooth broadcasting immediately after the ranging is also in a time-sharing and alternate mode;

7. after detecting the bluetooth broadcast containing the ranging result from the tag, the tag may sort the ranging information and broadcast the ranging information, and mark N of the number of forwarding times, where the tag may set the number of forwarding times to be less than the number of configurable limit times N0, for example, N0 ═ 3 represents that a ranging packet is forwarded 3 times at most;

by the method, ranging data can be transmitted back to the base station in a relay manner, and loss of ranging results due to the fact that part of the main tags are not in the Bluetooth scanning range of the base station is avoided;

8. after the broadcasting is finished or after the preset time T2 required by one round of UWB ranging and Bluetooth broadcasting is exceeded, entering the next ranging period and continuing the 2-7 circulation;

the method mainly avoids UWB co-frequency band interference, adopts a mechanism similar to collision avoidance, firstly detects whether information is received or not, and randomly delays for sending if the information is not received, so that the information can be sent firstly when the random delay is short, and then sent after the random delay is long, thereby avoiding the condition that only one information can be analyzed when the information is sent in the same receiving processing time period.

In addition, the problem that the shielded tag cannot measure the distance all the time and occupies more time slot resources of the main tag (M is 1) can be solved by queuing the tags failing to measure the distance to the end, so that the tag capacity is indirectly improved.

In addition, the mechanism combining UWB and Bluetooth can coordinate the master-slave relationship M and the fixed point relationship A of the label and confirm the self-positioning condition F while reducing the power consumption; meanwhile, the ranging result is uploaded through the Bluetooth, so that the Bluetooth gateway or other intelligent devices such as industrial tablets and mobile phones with Bluetooth can receive the ranging result conveniently, and the position information is further analyzed and displayed on a map. If the intelligent devices are matched with the ranging labels, self positioning and navigation can be realized. For example, a firefighter carrying a tag can acquire the position information of a member carrying the tag at any time through an industrial tablet, and can support teammates through navigation or arrange personnel nearby for support. Because the data is directly transmitted from the tag to the industrial tablet or the smart phone, the data does not need to be forwarded through a cloud platform or a server and the like, and the time delay of the position data is reduced to the minimum.

High-precision positioning algorithm based on label distance

Judging the known coordinate node number measured by the label, and when the known coordinate node number is more than or equal to 3, adopting the following high-precision positioning algorithm adopting an adjacent label distance model

Let n (n ≧ 3) known nodes, the node coordinates are (xi, yi) (i ═ 1, 2.. n), the unknown node coordinates are (x, y), the measurement distances between the unknown node and each known node are di (i ═ 1, 2.. n)

1) Establishing a distance equation between a known node and an unknown node

2) Subtracting the nth equation from the first n-1 equations to obtain a linear equation

AX＝b

Wherein

3) Solving the above equation by least square method

Get X ═ A^TA)^-1A^Tb

After the label coordinates of the unknown coordinate nodes are calculated, the node states of the unknown coordinate nodes are updated to be known coordinate nodes, the known node numbers around all the unknown nodes are refreshed, and therefore the number of the known labels of the rest unknown nodes which are distant from the label is measured to be + 1.

The process is repeated continuously until all the label coordinates of the 3 different label distances are calculated.

When the number of the known coordinate nodes is 2, directly adopting a geometric mode, solving the equation of the circle to calculate the intersection point of the two circles, judging the position of the intersection point, and eliminating the coordinates close to other nodes.

When the number of the known coordinates is 1, drawing a dotted circle by taking the known coordinates as the center of a circle and the measured distance as the radius, and using the intersection point of the extension lines of other labels to the nodes of the known coordinates and the circle as a boundary point to real-line the arc part far away from other labels to represent the possible coordinate position of the unknown label.

In order to improve the precision of the tag, the distance measurement period can be shortened (the distance measurement frequency is accelerated), according to normal distribution, the head and the tail of all distance values received in a period of time reaching the same node are respectively removed, then averaging is carried out, the distance values are calculated in the process, distance statistics is carried out after 86 times of distance measurement, the statistics times and the distances are basically in normal distribution, the upper graph is the effect after Excel curve fitting, the distances with the head and tail statistics times smaller than 5 can be omitted, only the distance average value close to the center is calculated, and the statistics times are larger than 5. This approach is superior to requiring a large number of range measurements, which increases power consumption. This can significantly improve the coordinate accuracy in the case of a relatively stationary tag position.

Example 1: application of AI ad hoc network positioning system in emergency rescue

The system adopts a 1+ N mode, 1 central node (a vehicle-mounted remote receiving base station) + N positioning labels (carried by rescuers).

The central node function is mainly used for commanding and scheduling and obtaining the positions of all the positioning labels.

The positioning tag adopts an AI ad hoc network mode, autonomously learns, mutually measures the distance with 3 nearby tags and transmits the distance measurement information back to the central node.

In addition, after the positioning tag triggers the help-seeking mode, the central node and three nearby tags can be informed to come for rescue, and the tags receiving the help-seeking information can measure the angle and the distance of the alarm tag in a PDOA and TWR mode so as to go forward for support;

the vehicle-cutting UWB long-distance ranging base station can collect ranging information and alarm information of the label, and displays the relative position of the label after analysis and modeling. And the absolute position is obtained according to the built-in high-precision Beidou positioning module, and the absolute positions of other labels are calculated. Thereby providing a position basis for personnel allocation;

the SOS help seeking function comprises that after a tag 0 presses a 1s emergency help seeking key for a long time, the tag enters a help seeking mode, emergency help seeking information is sent to a vehicle-cutting UWB base station through UWB broadcasting, and alarm information is added in a UWB ranging packet, wherein the SOS help seeking function is cancelled, when ranging data of the tag 0 and other tags is less than 0.3m, or the tag 0 is pressed for 2 times for a short time, and when the tag 0 actively exits the help seeking mode by pressing the 1s key for a long time, the tag 0 sends exit emergency help seeking information through UWB broadcasting, and the alarm information is cancelled in the UWB ranging packet;

after receiving the SOS alarm information of the tag 0, the nearby tag 1 can vibrate for reminding; double-click confirmation of the button triggers a forward to support. At this time, the tag 1 transmits the support information to the background via UWB and performs ranging with the tag 0. Both of them adjust the buzzer frequency according to the distance information (if there are other tags going to support, the alarm end tag 0 only sounds according to the distance of the nearest tag). After the tag 1 triggers to go to support, entering a PDOA angle measurement + TWR distance measurement mode; the direction of the alarm device is indicated by a direction indicator lamp, and the distance of the alarm device is prompted by a buzzer.

Example 2: social distance maintenance

This system adopts the mode of 1+ N, and 1 central node uses bluetooth gateway or long-range UWB basic station, collects label range finding data, and N range finding labels (as shown in the following figure UWB + bluetooth label) are used for two liang of range finding.

Wherein, bluetooth gateway or long-range UWB ranging basic station can collect and take notes the alarm information of label, convenient follow-up tracing to the source. Each ranging tag can measure with nearby tags in two directions, and each ranging tag can measure with nearby tags in two directions.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An ad hoc network positioning system based on UWB is characterized by comprising a long-distance Bluetooth gateway or UWB base station, 1 or a plurality of fixed-point tags, 1 or a plurality of nearby tags and a server, wherein the long-distance Bluetooth gateway or UWB base station, the 1 or a plurality of tags and the server form the ad hoc network positioning system, the long-distance Bluetooth gateway or UWB base station acquires coordinate data of the long-distance Bluetooth gateway or UWB base station through a high-precision positioning module, each fixed-point tag can perform bidirectional distance measurement with the nearby tags and upload distance measurement information to the long-distance Bluetooth gateway or UWB base station in a broadcasting mode, the server is used for collecting and recording tag information and positioning the tags,

the system further comprises a TWR positioning system, wherein the TWR positioning system is used for determining a coordinate node (xi, yi) of the fixed point label, i =1, 2.. n, and the coordinate node is used as a known coordinate node;

calculating an unknown coordinate node (x, y) according to the known coordinate node;

the fixed point label has known position coordinates or coordinates relative to a UWB base station, and the UWB base station is provided with a high-precision positioning module for calculating the coordinates of the fixed point label;

the high-precision positioning module judges the number n of known coordinate nodes measured by the label, wherein the number n of the known coordinate nodes is divided into three conditions of n being more than or equal to 3, n =2 and n = 1;

all the tags are defaulted to work in a UWB base station receiving mode after the tags are initialized, Bluetooth broadcasting and scanning are started, broadcasting is performed for 500ms by default, and broadcast information comprises an ID, a master-slave relation flag bit M, a fixed point tag flag bit A and a quasi-fixed point tag flag bit F;

the TWR positioning system comprises a module A and a module B, wherein each module generates an independent time stamp from the start, a transmitter of the module A transmits a pulse signal with a request property at the Tsp of the time stamp, the module B transmits a signal with a response property at the TSR moment, the signal is received by the module A at the TRR moment of the time stamp of the module A and then is transmitted by the module B to be received by the TRF, the flight time T of the pulse signal between the two modules is calculated according to two data, and therefore the flight distance r and the flight time T are determined, and accordingly the flight distance r can be represented by the following formula:

T=(2TRR-TSP-2TSP+TRP+TRF-TSF)/4;

r = T × C, wherein C is the speed of light;

the distance measurement scheme based on the PDOA algorithm of the DW1000 scheme is as follows, in order to realize the angle estimation of tag, two identical antennae with the interval d < lambda/2 are placed on the UWB base station, the phase difference of a certain signal on the tag reaching the two antennae is in the range of-180 DEG to 180 DEG, the measured phase difference phi is used for converting into the distance difference P = lambda phi/(2 pi), the distance r is obtained by using the flight time, and the geometrical relation series equations are as follows:

r^2=x^2+y^2;(x-d)^2+y^2=(r-P)^2;

finally, positioning coordinate data (x, y) of the tag label are obtained;

in order to realize the conversion from the relative position to the absolute position, a Beidou high-precision positioning module is usually installed in a positioning base station, and 3 known coordinates are installed, or a fixed point label relative to the known coordinates of the base station is used as a position initialization reference;

ad hoc network positioning principle:

B. measuring the distance between the surrounding labels and the fixed point labels, if the distance between a label and 3 fixed point labels is measured at the same time, drawing three circles according to the distance, wherein the intersection point is the coordinate of the label, and the label is converted into a quasi fixed point label;

D. if labels in individual edge zones exist, only 2 fixed point or quasi-fixed point labels which can be measured at the periphery can be obtained, the labels can calculate two coordinates by intersecting two circles, wherein one coordinate is close to other quasi-fixed point labels, and the other coordinate is far away from other labels;

E. if a certain label can only measure the distance with one label, the position of the label can be displayed on an arc drawn by the distance measured by the label, and the starting point and the ending point of the arc are positioned on the extension lines of other quasi-fixed point labels and the quasi-fixed point label 3 and the rubber pad of the circle;

F. when a single tag can not measure the distance with other tags, the position display keeps the last record and is marked specially;

G.

1) after all the tags are initialized, all the tags work in a UWB receiving mode by default, Bluetooth broadcasting and scanning are started, the broadcasting information is broadcasted for 500ms by default once, one-dimensional forwarding frequency marking bit N, UWB ID, master-slave relation marking bit M, fixed point tag marking bit A and quasi-fixed point tag marking bit F are contained in the broadcasting information, wherein N =0 represents an original ranging packet, N = other integer values represent the forwarding frequency of the ranging packet, Reserve data comprises ranging distance and tag ID data of both ranging sides, the master-slave relation marking bit is used for confirming who initiates a ranging request, all the fixed point tags are master M =1 under the default condition, all the other tags are slave M =0 under the initial condition, the quasi-fixed point tag marking bit F is used for distinguishing whether the tags can determine own coordinates through ranging, an initial value F =0 represents that the tags are not located, and the F value is modified along with the ranging subsequently, f =1 single label location, F =2 double label location, F =3 multi label location, F =3 for a fixed point label indicates multi label location, and the broadcast format is as follows:

2) all the Bluetooth parts of the tags scan surrounding tags in the rest non-broadcast time, and record various flag bits, IDs (identity) and RSSI (received signal strength indicator) information of the surrounding tags, wherein T0 and T0 are data updating periods;

3) the fixed point tag defaults to make M =1, the quasi-fixed point tag flag bit F =3, a distance measurement request is initiated after a random delay function based on UWBID as an initial value is used, the request information comprises ID information of non-fixed point tags, if a certain fixed point tag receives distance measurement requests of other tags in a delay period, the fixed point tag is continuously opened for receiving, the random delay function is refreshed, and if no UWB data packet is received after the delay is finished, the distance measurement request is initiated;

4) the non-fixed point label defaults as a slave, according to the master-slave relation zone bit in the information scanned by the Bluetooth, if the scanned data has no master, the non-fixed point label modifies itself as a master, and sends a UWB ranging request after random delay by taking the ID of the non-fixed point label as an initial value, if the delay period indirectly receives other ranging requests, the non-fixed point label continues to be opened for receiving and refreshing the delay time;

5) after the non-fixed point tag finishes ranging in one period, counting the total number N of F =3 in the tag with successful ranging, if N >2, modifying the self quasi-fixed point tag mark position F =3, if N =2, F =2, if N <2, F = N;

6) after the F value is refreshed, all the distance measurement main tags M =1 start to broadcast the distance measurement result by using the Bluetooth, and as the distance measurement is finished in a time-sharing and alternate mode, the Bluetooth broadcast immediately after the distance measurement is also in a time-sharing and alternate mode;

7) after detecting the Bluetooth broadcast containing the ranging result from the tag, the tag can sort the ranging information and then broadcast the ranging information, and mark N of the forwarding times, and the tag can set the broadcast of which the forwarding times are less than the number NO of configurable limit values;

8) the method comprises the steps of broadcasting, entering a next ranging period after the broadcasting is finished or after a preset time T2 required by one round of UWB ranging and Bluetooth broadcasting is exceeded, continuing a 2-7 cycle, and aiming at the situation that a tag failed in ranging queues to the end, the problem that a shielded tag cannot measure the distance all the time and occupies more time slot resources of a main tag M =1 can be solved, so that the capacity of the tag is indirectly improved, in addition, a mechanism combining UWB and Bluetooth can also be used for coordinating the master-slave relation M and the fixed-point relation A of the tag and confirming the self-positioning condition F while reducing the power consumption, meanwhile, the ranging result is uploaded through Bluetooth, so that convenience is brought to a Bluetooth gateway or other industrial panels with Bluetooth, mobile phone intelligent equipment receives the ranging result, further analyzes the position information and displays the position information on a map, if the intelligent equipment also matches the ranging tag, the self-positioning and navigation can be realized, and the data is direct data from the tag to the industrial panels or the intelligent mobile phone The high-precision positioning algorithm based on the label distance judges the number of known coordinate nodes measured by the label, when the number of the known coordinate nodes is more than or equal to 3, the high-precision positioning algorithm adopting an adjacent label distance model can be adopted to set n known nodes, wherein n is more than or equal to 3, and the node coordinates are respectively (x is more than or equal to 3)_i,y_i) I =1,2,. n, the unknown node coordinates are (x,y), the measurement distance between the unknown node and each known node is di, i =1,2

1.1) establishing a distance equation between a known node and an unknown node;

1.2) subtracting the nth equation from the first n-1 equations of the equation set to obtain a linear equation AX = b;

1.3) solving by least squares the above equation yields X = (A)^TA)^-1A^Tb;

After the label coordinates of the unknown coordinate nodes are calculated, the node state of the unknown coordinate nodes is updated to be known coordinate nodes, the number of the known nodes around all the unknown nodes is refreshed, therefore, for the other unknown nodes with the distance measured by the label, the known label number is plus 1, the processes are continuously repeated until all the label coordinates with the 3 different label distances are calculated, when the known coordinate nodes are 2, the intersection point of two circles is calculated by solving the equation of the circles directly in a geometric mode, the intersection point position is judged, the coordinates close to other nodes are omitted, when the known coordinate number is 1, a dotted circle is drawn by taking the known coordinate as the center of a circle and the measured distance as the radius, the intersection point of the extension lines of other labels to the known coordinate nodes and the circle is used as a boundary point, the circular arc part far away from other labels is subjected to real-line representation of the possible coordinate position of the unknown label, and the precision of the label is improved, the distance measurement period can be shortened, according to normal distribution, all distance values within a period of time of reaching the same node are received, the head and the tail are respectively removed, then averaging is carried out and then the distance is introduced into the flow for calculation, distance statistics after 86 times of distance measurement is carried out, the counting times and the distance are basically in normal distribution, the distance with the counting times being less than 5 from the head to the tail can be omitted, only the distance average value which is close to the center and the counting times being more than 5 is calculated, the method is superior to the method which needs a large amount of distance measurement, power consumption can be increased, and under the condition that the position of a label is relatively static, the coordinate precision can be obviously improved.