Self-recalling time synchronization method and long-endurance positioning system

Abstract

The application provides a self-recalling time synchronization method and a long-endurance positioning system, and relates to the technical field of UWB positioning systems. The self-recalling time synchronization strategy is adopted, so that the positioning tag can keep time synchronization with a synchronous scheduling base station when the MCU enters a low-power mode, and then the time synchronization between large-scale positioning tags is kept, on the one hand, the sleep duration of the positioning tag is maximally ensured, and the endurance of the positioning tag is prolonged, and on the other hand, the possibility of conflict of positioning information between tags is minimized through a grouping scheduling mode. The grouping time synchronization strategy is adopted, on the one hand, the unified scheduling mechanism and the random access mechanism are flexibly balanced, and the system performance is maximally improved, and on the other hand, when the positioning tag moves across domains and loses synchronization information, the self-recalling synchronization strategy is adopted, so that the synchronization recall is completed in a short time, and the robustness of the system is improved.

Description

Technical Field

[0001] This invention relates to the field of UWB positioning system technology, specifically to a self-recall time synchronization method and a long-endurance positioning system. Background Technology

[0002] This invention is applicable to multi-moving target monitoring in indoor locations such as prisons, detention centers, mental hospitals, drug rehabilitation centers, residential communities, hospitals, nursing homes, and kindergartens. In these indoor positioning scenarios, industries often have specific requirements for both positioning accuracy and battery life. However, currently, no mature indoor positioning system solution, both domestically and internationally, can simultaneously meet these requirements. This is because existing technologies and systems have their own limitations in terms of positioning accuracy, deployment difficulty, and battery life. Currently, the most widely used indoor positioning system uses Wi-Fi fingerprint positioning, but Gaode Maps' method, which combines Wi-Fi fingerprint and iBeacon positioning, only achieves a positioning accuracy of 3-5 meters. Regarding high-precision positioning, domestic manufacturers such as Tsinghua Research Institute showcase application cases in different industries using Qorvo's official website positioning solution. However, due to information collision issues between tags, problems with long-distance base station information collection, and the inability of positioning tags to effectively utilize sleep scheduling and power control for extended battery life, this solution is also inadequate for long-term battery life requirements. Furthermore, in densely populated environments, positioning using wireless measurement methods is also affected by factors such as wireless signal interference.

[0003] Therefore, considering the current state of industry development and the urgent need for indoor positioning monitoring, the selection of precise monitoring solutions must take into account the requirements of small size, high precision, and long battery life in order to enable new technologies and methods such as artificial intelligence and UWB positioning to be used in business, and to create an indoor positioning monitoring management model with indoor monitoring management as the core. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a self-recall time synchronization method, comprising the following steps:

[0005] S1. The synchronous scheduling base station broadcasts time synchronization frames to the positioning base station and positioning tag according to the synchronization interval to perform time synchronization;

[0006] S2. After the positioning tag is started, it waits to receive a time synchronization frame, and starts the positioning tag's sleep scheduling and time synchronization function according to the received time synchronization frame.

[0007] Furthermore, after the positioning tag wakes up from sleep, it waits to receive a time synchronization frame.

[0008] If no time synchronization frame is received, the wake-up time is adjusted forward slightly, and the next sleep-wake cycle begins.

[0009] If the time synchronization frame is received, the time stamp of the time synchronization frame is recorded, and the synchronization group number in the time synchronization frame is read.

[0010] Further, if the synchronization group number is the same as the tag group number, the RTC time is updated using the time stamp of the time synchronization frame to complete time synchronization and enter the next sleep wake-up period; if the synchronization group number is different from the tag group number, the synchronization calibration time T is calculated according to the following formula to complete recall synchronization and enter the next sleep wake-up period:

[0011] T=(Gcount-1+Gnumber-GTn) *g;

[0012] Wherein, the synchronization group number is Gnumber, the synchronization group number is Gcount, the guardian duration is g, and the tag group number is GTn.

[0013] The application further provides a long-endurance positioning system based on the self-recall time synchronization method, comprising a synchronization scheduling base station, a positioning base station, a positioning tag and a positioning server; the synchronization scheduling base station and the positioning tag adopt the self-recall time synchronization method to perform time synchronization.

[0014] The synchronization scheduling base station informs the positioning base station to perform time synchronization in the form of a time synchronization frame and schedules the positioning tag to send a positioning frame; the positioning base station receives the time synchronization frame to complete time synchronization and then receives the tag positioning frame to complete positioning of the positioning tag; the positioning tag performs time synchronization according to the self-recall time synchronization method and performs sleep scheduling based on the synchronization time, receives the time synchronization frame during wake-up period and sends the positioning frame.

[0015] After each positioning base station receives the positioning frame sent by the positioning tag, the receiving time stamp is recorded, and the positioning frame and the receiving time stamp are sent to the positioning server through Ethernet; after the positioning server receives the positioning frame and the receiving time stamp of each positioning base station, the position of the positioning tag is calculated.

[0016] Further, the time synchronization frame comprises a synchronization scheduling base station ID, a synchronization number Sn, a guardian duration g, a synchronization group number Gnumber, a synchronization group number Gcount and an RTC time of the synchronization scheduling base station.

[0017] Further, the synchronization scheduling base station comprises the following functions:

[0018] Multiple ranging is performed with multiple positioning base stations, the distance average value is taken, and each positioning base station calculates a time calibration value pair;

[0019] A grouping frame is sent to the positioning tag, and the grouping frame comprises a grouping number and a plurality of tag IDs.

[0020] It has time synchronization frame opening and closing function, when closing, it no longer sends time synchronization frame.

[0021] Further, the positioning base station has the following functions:

[0022] Receiving the time synchronization frame of the synchronous scheduling base station, recording the synchronization number, recording the time stamp of receiving the time synchronization frame, and completing time synchronization.

[0023] Receiving the time synchronization frame of the synchronous scheduling base station, recording the synchronization number, recording the time stamp of receiving the time synchronization frame, and completing time synchronization.

[0024] Receiving the positioning frame sent by the positioning tag, packaging the positioning frame, adding the time stamp of receiving the positioning frame, the synchronization number, the time stamp of the time synchronization frame, the calibration time and the ID of the synchronous scheduling base station to the Ethernet or the switch.

[0025] Further, the positioning tag has the following functions:

[0026] It has the power indication function of sending the positioning information, the disassembly alarm function of sending the positioning information, and the leave request sending function of sending the positioning information.

[0027] After the positioning tag is time synchronized, the positioning information sent carries the positioning tag ID, the synchronous scheduling base station ID, the synchronization number, the transparent content, the grouping number, the power information, the long daemon mark, the disassembly indication bit, the leave information and the check information.

[0028] The grouping default value memory function.

[0029] Further, the positioning server receives the network port frame information from the positioning base station, filters the time stamp information of each positioning base station with the same positioning number and the same positioning tag ID according to the network port frame information, and positions the positioning tag, reads the grouping number, the power information, the long daemon mark, the disassembly indication bit and the leave information, and realizes the electronic fence alarm, the disassembly alarm and the leave function.

[0030] Compared with the prior art, the present application has the following beneficial technical effects:

[0031] The time synchronization strategy of self-recalling adopted by the present application can make the positioning tag keep time synchronization with the synchronous scheduling base station when the MCU enters the low-power mode, and further make the large-scale positioning tags keep time synchronization, which can maximize the sleep time of the positioning tag, prolong the endurance of the positioning tag, and on the other hand, can make the conflict possibility of positioning information between tags be minimized through grouping scheduling, and improve the system positioning reliability.

[0032] The grouping time synchronization strategy can flexibly balance between the unified scheduling mechanism and the random access mechanism, maximally improve the system performance, and when the positioning tag loses the synchronization information during cross-domain movement, the self-recalling synchronization strategy can be used to complete the synchronization recalling in a short time and improve the robustness of the system. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0034] Figure 1 The synchronization flowchart of the synchronization scheduling base station.

[0035] Figure 2 The synchronization flowchart of the positioning tag.

[0036] Figure 3 The structure schematic diagram of the positioning system. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0038] In the specific embodiment drawings of the present application, in order to better and more clearly describe the working principles of the elements in the system and show the connection relationship of the parts in the device, only the relative position relationship between the elements is distinguished, and the signal transmission direction, connection order and the size, dimension and shape of the parts in the structure cannot be limited.

[0039] The self-recalling time synchronization method of the present application comprises the following steps:

[0040] S1, the synchronization scheduling base station broadcasts and sends the time synchronization frame to the positioning base station and the positioning tag according to the synchronization interval, and performs time synchronization.

[0041] Figure 1For synchronous scheduling base station synchronization flow chart, the synchronous scheduling base station broadcasts time synchronization frame (referred to as synchronization frame) to the positioning base station and the positioning tag according to the synchronization interval Interval (default 5 milliseconds) as the period, the synchronization frame includes: the synchronous scheduling base station ID (16 bits), the designated synchronization number Sn (one synchronization frame one synchronization number, 16 bits, the change range: 0-65534, 65535 is reserved unsynchronized mark), the guardian duration g (default 5 milliseconds), the synchronization group number Gnumber, the synchronization group number Gcount, the synchronization frame also includes the RTC time (24 bits) of the synchronous scheduling base station;

[0042] S2, the positioning tag starts to wait to receive the time synchronization frame, and starts the sleep scheduling and time synchronization function of the positioning tag according to the received time synchronization frame.

[0043] Figure 2 For the positioning tag synchronization flow chart, the positioning tag starts to wait to receive the synchronization frame, and starts the sleep scheduling and time synchronization function of the positioning tag if the synchronization frame is received;

[0044] After the positioning tag sleeps and wakes up, it waits to receive the synchronization frame within the interval time, and if no synchronization frame is received, it fine-tunes the wake-up time forward and enters the next sleep and wake-up cycle.

[0045] After the positioning tag sleeps and wakes up, if the synchronization frame is received within the interval time, the synchronization frame timestamp is recorded, the synchronization group number in the synchronization frame is read, and if the synchronization group number is the same as the tag group number, the synchronization frame timestamp is used to update the RTC time, and the time synchronization is completed; if the synchronization group number is different from the tag group number, the synchronization calibration time is calculated according to the following formula, and the recall synchronization is completed:

[0046] T=(Gcount-1+Gnumber-GTn) *g;

[0047] The synchronization group number is Gnumber, the synchronization group number is Gcount, the guardian duration is g, and the tag group number is GTn.

[0048] The application also proposes a long-endurance positioning system based on the self-recalled time synchronization method. The synchronization scheduling base station and the positioning tag adopt the same hardware RTC (Real Time Clock) clock design, and can also perform timing in the state of positioning tag microprocessor MCU (Microcontroller Unit) sleep. The system needs to pre-allocate a group number for each positioning tag, and determine the number of positioning tag synchronization groups that need to be time synchronized in the time synchronization system. The synchronization scheduling base station performs wireless time synchronization with the tag by sending a synchronization frame, and informs the next synchronization time of the positioning tag through the group number and the number of synchronization groups. The positioning tag calculates the next synchronization time according to the received synchronization frame, and completes a new round of time synchronization.

[0049] The long-endurance positioning system includes a synchronization scheduling base station, a positioning base station, a positioning tag, a positioning server, and a switch. As shown in the schematic diagram of the long-endurance positioning system, Figure 3 The synchronization scheduling base station communicates with the positioning base station and the positioning tag in a wireless manner, the positioning tag sends positioning information to each positioning base station in a wireless broadcast manner, the positioning base station transmits the information to the positioning server in an Ethernet manner, and the positioning server receives the positioning information sent by the multiple positioning base stations and solves the position of the tag.

[0050] The synchronization scheduling base station and the positioning tag adopt the above-mentioned self-recalled time synchronization method to perform time synchronization; the synchronization scheduling base station informs the positioning base station of time synchronization in the form of a synchronization frame, and schedules the positioning tag to send a positioning frame; the positioning base station receives the synchronization frame to complete time synchronization, and then receives the positioning frame of the tag to complete tag positioning; the positioning tag performs time synchronization according to the self-recalled time synchronization method, and performs sleep scheduling based on the synchronization time, receives the synchronization frame during the wake-up period, and sends the positioning frame. After each positioning base station receives the positioning frame sent by the positioning tag, a receiving time stamp is recorded, and the positioning frame and the receiving time stamp are sent to the positioning server through Ethernet. After the positioning server receives the positioning frame and the time stamp of each positioning base station, the position of the positioning tag is solved.

[0051] Embodiment 1

[0052] In the long-endurance positioning system, the synchronization scheduling base station has a 16-bit ID, and includes the following functions:

[0053] (a) M times of ranging with multiple positioning base stations in the positioning network, taking the average, each positioning base station calculates a time calibration value pair: [synchronization scheduling base station 16-bit ID, calibration value]; the default value of M is 15.

[0054] (b) The synchronization scheduling base station sends a packet frame to the positioning tag, which includes a packet number and several tag IDs, indicating that these tags belong to the same group. The packet number is a 16-bit natural number starting from 1; the tag ID is preferably 4, each being 32 bits.

[0055] (c) The synchronization scheduling base station uses the self-recalled time synchronization method described above to synchronize time with the positioning tag;

[0056] (d) It has a synchronization frame opening and closing function. When closed, it no longer sends synchronization frames.

[0057] The positioning base station has the following functions:

[0058] (a) Receive synchronization scheduling base station commands to complete multiple ranging, calculate time synchronization calibration value pair: [synchronization scheduling base station 16-bit ID, calibration value], record it down, and restart it;

[0059] (b) Receive synchronization frames from the synchronization scheduling base station, record the synchronization number, and record the time stamp T0 of receiving the synchronization frame to complete time synchronization;

[0060] (c) Receive the positioning frame sent by the positioning tag, package the positioning frame, and send it to the Ethernet or switch along with the time stamp (64 bits) of receiving the positioning frame, the synchronization number, the time stamp T0 of the synchronization frame, the calibration time, and the base station ID (16 bits) and other information;

[0061] The positioning tag has the following functions:

[0062] (a) It has the functions of sending power indicators with positioning information, sending disassembly alarms with positioning information, and sending leave requests with positioning information. A dual-color light is used to determine whether the leave request is sent successfully. When the red light is pressed, it becomes a green light, indicating that the request is successful;

[0063] (b) The positioning tag uses the self-recalled time synchronization method described above to synchronize time with the synchronization scheduling base station;

[0064] (c) After time synchronization, the positioning tag sends the tag ID (32 bits), synchronization scheduling base station ID (16 bits), synchronization number (16 bits, obtained from the synchronization frame, if no synchronization frame from the synchronization scheduling base station is received within the guard time, the synchronization number is the same as the last one), transparent content (8 bits), packet number, power information, long guard marker, disassembly indicator bit, leave information, and check information in the positioning information;

[0065] (d) Group default value memory function, restart can read out.

[0066] The positioning server has the following functions:

[0067] The positioning server receives the network interface frame information from the positioning base station, filters the time stamp information of each base station with the same positioning number and the same positioning label ID according to the base station network interface frame format, and performs positioning on the positioning label. Meanwhile, the grouping number, power information, long guard marker, disassembly instruction bit, leave information and the like are read to realize the functions of electronic fence alarm, disassembly alarm, leave and the like.

[0068] Embodiment 2

[0069] The time synchronization function of the synchronous scheduling base station: the synchronous scheduling base station broadcasts and sends the time synchronization frame (referred to as synchronization frame) to the positioning base station and the positioning label according to the synchronization interval Interval (default 5 milliseconds) as a period. The synchronization frame includes the ID (16 bits) of the synchronous scheduling base station, the specified synchronization number Sn (one synchronization number for one synchronization frame, 16 bits, the change range: 0-65534, and 65535 is the reserved unsynchronized marker), the guard time length g (default 5 milliseconds), the synchronization group number Gnumber, the synchronization group number Gcount, and the RTC time (24 bits) of the synchronous scheduling base station;

[0070] The time synchronization function of the positioning label:

[0071] (a) The positioning label has two states: long guard state and synchronization state;

[0072] (b) The synchronization state is divided into night mode (default RTC time is from 9:00 at night to 5:00 in the morning) and non-night mode (default RTC time is from 5:00 in the morning to 9:00 at night)

[0073] (c) The label is in the long guard state after starting. In the long guard state, the label does not sleep, and only enters the synchronization state and starts periodic sleep after receiving the synchronization frame;

[0074] (d) In the long guard state, the label receives the synchronization frame, turns to the synchronization state, and updates the RTC time. If the group number in the synchronization frame is consistent with the group number of the label, the label broadcasts and sends the positioning frame to each positioning base station;

[0075] (e) In the non-night mode of the synchronization state, the label fine-tunes the wake-up time window forward if the synchronization frame is not received within the wake-up time;

[0076] (f) In the non-night mode of the synchronization state, the label keeps the synchronization state. If the synchronization frame is received, the next synchronization time is calculated according to the formula T=(Gcount-1+Gnumber-GTn) *g according to the group number GTn of the label, the synchronization group number Gnumber, the synchronization group number Gcount, and the guard time length g, and the sleep setting is performed. Then, the positioning frame is sent and the sleep is performed;

[0077] (g) When the synchronization state night mode, the tag wakes up once in 10 minutes, sends the positioning frame, the synchronization number is set to 65535, indicating that it is not synchronized.

[0078] The application is suitable for a time synchronization method of node dormancy scheduling, and the node can keep time synchronization with a synchronization scheduling base station in the MCU dormancy mode, avoiding conflict when a large number of positioning tags send positioning information.

[0079] The grouping time synchronization strategy of the application can calculate the next synchronization time in the case of receiving any synchronization frame, and can find the synchronization again in the case of losing time synchronization.

[0080] In the above embodiments, all or part of the embodiments can be implemented by software, hardware, firmware or any combination thereof. When implemented by software, all or part of the embodiments can be implemented in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of the application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network or other programmable devices. The computer instructions can be stored in a computer-readable storage medium or transmitted by the computer-readable storage medium. The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server, data center, etc. integrated with one or more available media sets. The available media can be a magnetic medium (for example, a floppy disk, a hard disk, a magnetic tape), an optical medium (for example, a DVD), or a semiconductor medium (for example, a solid state disk (SSD)) and the like.

[0081] The above is only a specific embodiment of the application, but the protection scope of the application is not limited thereto. Any skilled person in the art can easily think of various equivalent modifications or replacements within the technical range disclosed in the application, and these modifications or replacements should be covered in the protection scope of the application. Therefore, the protection scope of the application should be subject to the protection scope of the claims.

Claims

1. A self-recall time synchronization method, characterized by, Comprising the following steps: S1, the synchronous scheduling base station broadcasts time synchronization frames to the positioning base station and the positioning tag according to the synchronization interval, for time synchronization; S2, the positioning tag starts and waits to receive the time synchronization frame, and starts the sleep schedule and time synchronization function of the positioning tag according to the received time synchronization frame; After the positioning tag wakes up from sleep, it waits to receive the time synchronization frame, If no time synchronization frame is received, the wake-up time is fine-tuned forward, and the next sleep-wake cycle is entered; If the time synchronization frame is received, the timestamp of the time synchronization frame is recorded, and the synchronization group number in the time synchronization frame is read; If the synchronization group number is the same as the tag group number, the RTC time is updated using the timestamp of the time synchronization frame to complete time synchronization, and the next sleep-wake cycle is entered; if the synchronization group number is different from the tag group number, the synchronization calibration time T is calculated according to the following formula to complete recall synchronization, and the next sleep-wake cycle is entered: T=(Gcount-1+Gnumber-GTn) *g; Wherein, the synchronization group number is Gnumber, the synchronization group number is Gcount, the guard duration is g, and the tag group number is GTn.

2. A long endurance positioning system based on self-recall time synchronization method, characterized in that, Comprising: Synchronous scheduling base station, positioning base station, positioning tag, positioning server; the synchronous scheduling base station and the positioning tag use the self-recall time synchronization method of claim 1 for time synchronization; The synchronous scheduling base station informs the positioning base station to perform time synchronization in the form of a time synchronization frame, and schedules the positioning tag to send a positioning frame; the positioning base station receives the time synchronization frame to complete time synchronization, and then receives the tag positioning frame to complete positioning of the positioning tag; the positioning tag performs time synchronization according to the self-recall time synchronization method, and performs sleep scheduling based on the synchronization time, and receives the time synchronization frame during the wake-up period and sends the positioning frame; After each positioning base station receives the positioning frame sent by the positioning tag, it records the reception timestamp, sends the positioning frame and the reception timestamp to the positioning server through Ethernet, and the positioning server receives the positioning frame and the reception timestamp from each positioning base station to solve the position of the positioning tag.

3. The long endurance positioning system of claim 2, wherein, The time synchronization frame comprises: the synchronous scheduling base station ID, the synchronization number Sn, the guard duration g, the synchronization group number Gnumber, the synchronization group number Gcount, and the RTC time of the synchronous scheduling base station.

4. The long endurance positioning system of claim 3, wherein, The synchronous scheduling base station comprises the following functions: a) Multiple ranging with multiple positioning base stations, taking the average distance, and each positioning base station calculating its own time calibration value pair; b) Sending a grouping frame to the positioning tag, the grouping frame comprising a grouping number and a plurality of tag IDs; c) Having a time synchronization frame opening and closing function, when closed, no longer sending time synchronization frames.

5. The long endurance positioning system of claim 4, wherein, The positioning base station has the following functions: a) Receiving the synchronous scheduling base station command to complete multiple ranging and calculate the time synchronization calibration value pair; b) Receiving the time synchronization frame of the synchronous scheduling base station, recording the synchronization number, recording the timestamp of the received time synchronization frame, and completing time synchronization; c) receiving the positioning frame from the positioning tag, packaging the positioning frame, adding the time stamp of receiving the positioning frame, the synchronization number, the time stamp of the time synchronization frame, the calibration time and the synchronization scheduling base station ID to send to the Ethernet or switch.

6. The long endurance positioning system of claim 5, wherein, The positioning tag has the following functions: a) having the power indication function with the positioning information, the disassembly alarm function with the positioning information, the leave request sending function with the positioning information; b) the positioning tag ID, the synchronization scheduling base station ID, the synchronization number, the transparent content, the grouping number, the power information, the long guardian mark, the disassembly indication bit, the leave information and the check information carried in the positioning information sent after the time synchronization of the positioning tag; c) the grouping default value memory function.

7. The long endurance positioning system of claim 6, wherein, The positioning server receives the network port frame information from the positioning base station, screens the positioning base station time stamp information with the same positioning number and the same positioning tag ID according to the network port frame information, positions the positioning tag, reads the grouping number, the power information, the long guardian mark, the disassembly indication bit and the leave information at the same time, realizes the electronic fence alarm, the disassembly alarm and the leave function.

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