Distributed time slot dividing method of UWB positioning systemTechnical Field
The invention relates to the technical field of time slot division methods, in particular to a distributed time slot division method of a UWB positioning system.
Background
UWB positioning technology is widely used in mine underground, and is currently being extended and applied and expanded to equipment positioning, man-machine approach detection and the like by a personnel accurate positioning system, and meanwhile UWB accurate positioning in a coal mine is ended and extended to position service on the mine from position service in the mine underground, such as coal washing fields, open pit coal mines and the like. Due to the prolongation of the usage scenario, the requirements on the capacity and the positioning speed of the positioning service are higher, so that the tag needs to be accessed in a time slot mode in the TOF positioning system. However, in the field deployment process, since the positioning nodes are usually relatively independent, the positioning nodes have a distributed characteristic, that is, there is no unified clock synchronization and time slot allocation positioning node.
The common time slot method is provided with a central processing positioning node, and the positioning node processes the work of clock synchronization and time slot division, and the system has simple structure but is difficult to deploy on site by using the method, and particularly in complex underground scenes of coal mines, the time slot allocation is difficult to be carried out by using the central processing positioning node.
Chinese patent (application number CN202110935215.2, application date 20210816, grant bulletin number CN113382386B, grant bulletin date 20211116) discloses a UWB slot scheduling system and method applied in a vehicle welcome system, describing a way of connecting surrounding UWB keys in a single vehicle slot, and assisting with a 2.4G bluetooth channel.
Chinese patent (application number CN201110411255.3, application date 20111212, grant bulletin number CN102404856B, grant bulletin date 20140507) discloses a time slot reservation algorithm based on a distributed reservation protocol in ultra wideband UWB, describing that using a time slot method for UWB data transmission is greatly different from using UWB for ranging positioning.
Chinese patent (application number CN201610509724.8, application date 20160701, publication number CN106211310a, publication date 20161207) discloses an indoor positioning method based on UWB technology, describing whether access is performed using a time slot aloha method or a random access method in nature.
The Chinese patent (application number CN201911385918.1, application date 20191229, grant bulletin number CN111163431B and grant bulletin date 20211119) discloses a method and a system for positioning a locomotive under a mine for UWB ultra-wideband wireless communication, which describe the method for positioning the locomotive, only the time slot method is mentioned, how time slots are divided is not described, and meanwhile, the distances used in the text partition a plurality of positioning nodes.
Chinese patent (application number CN202110974668.6, application date 20210824, publication number CN113766626A and publication date 20211207) discloses a time slot synchronization control method, equipment, storage medium and program product of a UWB positioning system based on Beidou time service, and describes a method for synchronizing time slot control clocks of a UWB base station under the Beidou time service.
Chinese patent (application number CN201910555412.4, application date 20190625, grant bulletin number CN110225461B, grant bulletin date 20210723) discloses an indoor positioning method based on UWB technology, describing time slot coordination among reference positioning base station, tag, time slot allocation by reference positioning base station.
Chinese patent (application number CN202011306548.0, application date 20201119, publication number CN112612000a, publication date 20210406) discloses an intelligent configuration platform suitable for fast deployment of UWB positioning systems, also by basic allocation of timeslots.
Chinese patent (application number CN201210420815.6, application date 20121029, publication number CN102970745A and publication date 20130313) discloses a UWB-based crowd-target real-time positioning system and an implementation method, wherein time slots are preset time slots, and dynamic allocation is not needed.
Chinese patent (application number CN201911329852.4, application date 20191220, publication number CN111077531A, publication date 20200428) discloses a UWB communication method, medium, terminal and device based on time division multiple access, wherein the positioning information is multiplexed in a frame mode and a time slot mode to improve positioning efficiency.
Chinese patent (application No. CN202110427593.X, application date 20210420, publication No. CN113115460A, publication No. 20210713) discloses a time slot selection method and related equipment, and mainly teaches a time slot selection method after collision occurs.
It is apparent that in the prior art, the slot allocation design is aimed at a slot allocation with a central positioning node, and the slot allocation problem in the distributed positioning system is not involved.
Disclosure of Invention
The present invention aims to solve at least one of the technical problems existing in the prior art.
Therefore, the invention provides a distributed time slot dividing method of a UWB positioning system, which relates to time synchronization among distributed positioning nodes in the time slot UWB positioning system and time slot division and time slot acquisition, adopts a distributed time slot allocation mode, does not need to process the positioning nodes in a central way, but acquires time slots through the coordination of the positioning nodes and labels, namely, the invention mainly aims at time slot allocation in the distributed positioning node system, does not have central positioning nodes, and only uses UWB single frequency band to carry out time slot division.
The distributed time slot division method of the UWB positioning system according to the embodiment of the invention comprises the following steps: step 1, time synchronization among distributed positioning nodes in a time slot allocation process is carried out; step 2, time slot dividing and time slot obtaining in the time slot distribution process are carried out.
The invention has the advantages that the clock synchronization and time slot division of the central positioning node are not needed, the positioning nodes in the positioning system have the distributed characteristics, and the communication among the positioning nodes is not needed; dividing a time slot method into two parts of time synchronization between positioning nodes, time slot dividing and time slot obtaining, wherein the coupling degree of the time slot dividing and the time slot obtaining is low, and the system is easy to expand; only clock synchronization and time slot information recording are needed among the positioning nodes, time slot division is not needed, and the implementation is relatively simple; the label end can acquire the time slot according to different service types, and the time slot division is more flexible.
According to an embodiment of the present invention, in the step 1, the method specifically includes the following steps:
step 1.1, setting priority by a positioning node: in the process of synchronizing the plurality of positioning node clocks, the low-priority positioning node clock is synchronized by the high-priority positioning node clock;
step 1.2, the positioning node perceives surrounding positioning nodes in the positioning process: the positioning nodes sense surrounding positioning nodes through the ranging response of the labels or surrounding positioning nodes;
step 1.3, the positioning node updates the clock according to the priority and the time information of surrounding positioning nodes: the positioning node corrects the clock thereof by sensing the priority and the time stamp of the positioning node, thereby realizing the clock synchronization with the positioning node with high priority.
According to an embodiment of the present invention, in the step 2, the method specifically includes the following steps:
Step 2.1, positioning node broadcast channel service condition: broadcasting channel service condition and time slot position occupied by the current label in the ranging process by each positioning node;
step 2.2, the label obtains the service condition of the channel and preempting the time slot: the label obtains a time slot table, and performs time slot preemption according to the use condition of a channel and the use condition of the time slot of the label stored in the positioning node;
Step 2.3, broadcasting and reporting the preempted time slot information by the tag: the label reports the preempted time slot information to all surrounding positioning nodes through broadcasting;
Step 2.4, updating the time slot service condition of the positioning node: each surrounding positioning node updates the recorded slot table.
According to one embodiment of the invention, the UWB positioning system supports a plurality of tags.
According to one embodiment of the invention, the positioning process of a single tag is to range a single tag to a plurality of positioning nodes, which are completely equivalent.
According to one embodiment of the invention, the time synchronization between the distributed positioning nodes is a process performed by a plurality of positioning nodes simultaneously.
According to one embodiment of the invention, the time slot division is a process performed by a plurality of positioning nodes simultaneously.
According to one embodiment of the invention, the slot acquisition is a process performed by multiple tags simultaneously.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
In order to make the above objects, features and advantages of the present invention more comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings may be obtained according to the drawings without inventive effort to those skilled in the art.
FIG. 1 is a flow chart of the present invention;
FIG. 2 is a schematic diagram of the positioning of a tag in accordance with the present invention;
FIG. 3 is a flow chart of time synchronization between distributed positioning nodes in the present invention;
FIG. 4 is a schematic diagram of the present invention prior to time synchronization of a positioning node;
FIG. 5 is a schematic diagram of the present invention after time synchronization of the positioning nodes;
FIG. 6 is a flow chart of time slot division and time slot acquisition in the present invention;
FIG. 7 is a schematic diagram of a label preemption slot process in the present invention;
FIG. 8 is a schematic diagram of a slot table after slot number 4 is selected;
fig. 9 is a schematic diagram of a slot table after slot number 6 is selected;
Fig. 10 is a schematic diagram of a slot table after slot 7 is selected.
Detailed Description
In order to make the technical problems, technical schemes and beneficial effects solved by the invention more clear, the invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Referring to fig. 1, the distributed time slot dividing method of the UWB positioning system of the present invention includes the following steps:
Step 1, time synchronization among distributed positioning nodes in a time slot allocation process is carried out, see fig. 3, and specifically comprises the following steps:
Step 1.1, setting priority by a positioning node: in the synchronization process of the plurality of positioning node clocks, the low-priority positioning node clock is synchronized by the high-priority positioning node clock.
The priority is an attribute of the positioning nodes, each positioning node has one priority, and different positioning nodes have different priorities, namely, a plurality of positioning nodes have a plurality of priorities, and 255 priorities are used in actual use. The high priority and low priority are relative terms of two positioning nodes. The purpose of the positioning node to set the priority is to synchronize the low priority positioning node clock with the high priority positioning node clock.
Step 1.2, the positioning node perceives surrounding positioning nodes in the positioning process: the positioning nodes sense the surrounding positioning nodes through the ranging responses of the labels or the surrounding positioning nodes.
Step 1.3, the positioning node updates the clock according to the priority and the time information of surrounding positioning nodes: the positioning node corrects the clock thereof by sensing the priority and the time stamp of the positioning node, thereby realizing the clock synchronization with the positioning node with high priority.
Under the condition that clock synchronization is not performed, the clocks of two positioning nodes are usually different, for example, the clock of the positioning node A is x, the priority of the positioning node A is 5, the clock of the positioning node B is y, the priority of the positioning node B is 6, that is, the priority 6 of the positioning node B is higher than the priority 5 of the positioning node A, the positioning node B perceives (the perceiving process is that the self clock is changed to y after the positioning node A is positioned (the label is possibly used and the ranging response is possibly also used), the self clock is changed to y after the positioning node A perceives the positioning node B, and the clock synchronization is realized, and the process is that the clock of the positioning node B is unchanged.
Referring to fig. 4, taking positioning node 1 and positioning node 2 as examples, positioning node 1 is a high priority positioning node, and positioning node 2 is a low priority positioning node, compared with positioning node 1 and positioning node 2. The positioning node 1 has 8 available time slots (No. 0 time slot, no. 1 time slot, no. 2 time slot, no. 3 time slot, no. 4 time slot, no. 5 time slot, no. 6 time slot and No. 7 time slot respectively), the positioning node 2 also has 8 available time slots (No. 0 time slot, no. 1 time slot, no. 2 time slot, no. 3 time slot, no. 4 time slot, no. 5 time slot, no. 6 time slot and No. 7 time slot respectively), and before the positioning node time synchronization, there is a time deviation between the positioning node 2 and the positioning node 1. Referring to fig. 5, after the positioning nodes time-synchronize, the clock of the positioning node 2 is aligned with the clock of the positioning node 1, that is, the time slot 0 of the positioning node 2 is aligned with the time slot 0 of the positioning node 1, the time slot 1 of the positioning node 2 is aligned with the time slot 1 of the positioning node 1, the time slot 2 of the positioning node 2 is aligned with the time slot 2 of the positioning node 1, the time slot 3 of the positioning node 2 is aligned with the time slot 3 of the positioning node 1, the time slot 4 of the positioning node 2 is aligned with the time slot 4 of the positioning node 1, the time slot 5 of the positioning node 2 is aligned with the time slot 5 of the positioning node 1, the time slot 6 of the positioning node 2 is aligned with the time slot 6 of the positioning node 1, and the time slot 7 of the positioning node 2 is aligned with the time slot 7 of the positioning node 1.
Step 2, dividing and acquiring time slots in the time slot allocation process, see fig. 6, specifically comprising the following steps:
step 2.1, positioning node broadcast channel service condition: each positioning node broadcasts the channel usage (i.e., the instant slot table) during the ranging process, as well as the slot position occupied by the current tag.
Wherein, there are a plurality of tags in the positioning system, the time slot is unchanged after the tags work stably (or the time slot selected by the tags each time is the same as the previous time slot after the tags work stably).
Step 2.2, the label obtains the service condition of the channel and preempting the time slot: the label obtains a time slot table, and performs time slot preemption according to the channel use condition and the self time slot use condition (time slot used in last ranging) stored in the positioning node;
Step 2.3, broadcasting and reporting the preempted time slot information by the tag: the label reports the preempted time slot information to all surrounding positioning nodes through broadcasting;
Step 2.4, updating the time slot service condition of the positioning node: each surrounding positioning node updates the recorded slot table.
Referring to fig. 7, taking positioning node 1 and positioning node 2 as examples, positioning node 1 is a high priority positioning node and positioning node 2 is a low priority positioning node, compared with positioning node 1 and positioning node 2. The positioning node 1 has 8 available time slots (No. 0, no.1, no. 2, no. 3, no.4, no. 5, no. 6 and No. 7 time slots respectively), the positioning node 2 also has 8 time slots (No. 0, no.1, no. 2, no. 3, no.4, no. 5, no. 6 and No. 7 time slots respectively), and the clock of the positioning node 1 is not moving, and the clock of the positioning node 2 is not aligned with the clock of the positioning node 1. The positioning node 1 responds that three time slots of a label number 0 time slot, a label number 1 time slot and a label number 2 time slot are used, the base point 2 responds that three time slots of a label number 2 time slot, a label number 3 time slot and a label number 5 time slot are used, the last time used time slot of the label is a number 1 time slot, and the number 1 time slot of the positioning node 1 is occupied, so that the label reselects a number 4 time slot after the ranging, the number 4 time slot is reported to all surrounding positioning nodes, all surrounding positioning nodes update a time slot table, and the process is repeated for each ranging of different labels. Referring to fig. 8, 9 and 10, of course, instead of selecting the number 4 slot, the number 6 slot and the number 7 slot may be selected, and the selection of the number 4 slot is only one choice, and how to select is determined by the tag. The time slots in the tag are also selected in a fixed manner, typically the time slot with the smallest number is selected, but different selection manners, such as selecting the time slot with the largest number, may be used.
UWB positioning systems support multiple tags, the behavior of which is the same. Multiple tags are distinct entities that do not have direct message interactions with each other.
The positioning process of the single tag is that the single tag is subjected to distance measurement with a plurality of positioning nodes, the plurality of positioning nodes are completely equivalent, and a center positioning node is not arranged; referring to fig. 2, the plurality of positioning nodes include a positioning node 1, a positioning node 2, a positioning node 3, a positioning node 4, a positioning node 5, and the like. Time synchronization between distributed positioning nodes is a process in which multiple positioning nodes are simultaneously operating. Time slot division is a process in which multiple positioning nodes are simultaneously involved. Slot acquisition is a process where multiple tags are doing at the same time.
Wherein ranging refers to distance measurement between two devices, one of which is a positioning node and the other of which is a tag. The distance measurement aims at measuring the distance between the tag and the positioning node, and is a precondition for the calculation of the tag position. The measured distance is provided by hardware and requires a sufficient amount of time during the ranging of the tag to the plurality of positioning nodes.
According to the distributed time slot dividing method of the UWB positioning system, the distributed positioning nodes realize clock synchronization among the positioning nodes in the modes of broadcasting, reading time stamps reported by labels and the like; in the ranging process with the tag, the distributed positioning node transmits the time slot allocation condition (namely the channel use condition) of the positioning node and the time slot information allocated by the current tag to the tag in the current ranging through message response; the label acquires the channel service conditions of a plurality of positioning nodes, performs time slot acquisition by combining time slot information acquired before the label, and reports the time slot acquisition conditions to the positioning nodes.
In addition, it should be noted that UWB (Ultra Wide Band) positioning systems mainly include two types, TOF (Time Of Flight) and TDOA (Time Of Arrival difference TIME DIFFERENCE Of Arrival). The TOF positioning method needs multiple message interactions, and the time required for one positioning is long, while the TDOA positioning method only needs to send one broadcast packet, and the time required for positioning is short. Therefore, when the system capacity is large, the TOF method is used, the wireless signal collision is caused by the random access mode, so that the positioning failure is caused, and a time slot scheme is generally needed to improve the access quantity of the positioning system. The time slot positioning method designed by the invention can well solve the problems that no communication exists between the positioning nodes (namely, the distributed positioning system has a time slot allocation scheme), the distributed positioning nodes can effectively solve the problems that the time slot division has conflict and the like.
The positioning node may also be referred to as UWB base station, node, positioning base station, etc., and the positioning node, UWB base station, node, positioning base station are indicated in the same meaning.
In addition, in the case of distributed positioning nodes, the positioning nodes can also perform wireless synchronization on time slot information periodically, but this affects the capacity of the positioning system and makes the design of the positioning system complex.
The foregoing description is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical solution of the present invention and the inventive concept thereof, and should be covered by the scope of the present invention.