Low-power-consumption UWB accurate positioning system and method for mine

Abstract

The invention relates to a low-power-consumption UWB accurate positioning system and method for a mine, and belongs to the field of accurate positioning. The system comprises a central station, a plurality of positioning base stations and a plurality of positioning terminals, the positioning base station is divided into an active power supply type and a battery power supply type; the plurality of positioning terminals are carried by underground personnel and are provided with UWB (Ultra Wideband) modules and rechargeable batteries; all the positioning base stations periodically work by adopting a low-power-consumption dormancy mechanism; when the positioning terminal is scanned, the positioning base stations carry out UWB distance measurement with the positioning terminal in a preset distance measurement time slot; all the positioning base stations and the positioning terminals work on a unified clock reference and transmit positioning data in an agreed communication time slot; and the positioning terminal automatically switches an active positioning mode or a passive positioning mode according to the located area, completes clock synchronization with the positioning base station and transmits a ranging result. According to the invention, the problem of difficult power supply of the positioning base station is solved, and the UWB accurate positioning system can be popularized and applied in an environment with difficult power supply.

Description

Technical Field

[0001] The present invention belongs to the field of precise positioning, and relates to a low-power UWB precise positioning system and method applicable to mines. Background Art

[0002] With the in-depth promotion of the construction of intelligent mines, the UWB (Ultra Wide Band) precise positioning system in mines, as the core technology for personnel positioning in coal mines, has been widely applied in domestic coal mining enterprises. By deploying positioning base stations and positioning tags carried by personnel, this system can achieve real-time precise positioning, trajectory tracking, and electronic fence management of underground workers, significantly improving the safety production management level and emergency rescue efficiency of mines. Especially in emergency disaster scenarios such as gas explosions and water inrush accidents, rescue personnel can quickly lock the positions of trapped personnel relying on the positioning system, greatly shortening the golden rescue time.

[0003] However, in high-gas areas of coal mines, gas drainage working faces in outburst mines, and complex driving roadways, the full deployment of the UWB positioning system faces severe challenges. Due to strict underground explosion-proof safety requirements, the laying of traditional AC power supply lines has multiple limitations: on the one hand, the installation of explosion-proof cables needs to follow safety specifications such as roadway support and ventilation, resulting in large wiring work and high maintenance costs; on the other hand, adding electrical equipment in gas-rich areas may pose safety hazards. This makes it impossible for positioning base stations to obtain stable power through conventional methods, resulting in insufficient base station coverage in key areas of the existing UWB system, forming positioning blind spots, and severely restricting the effectiveness of the precise positioning system.

[0004] In the prior art, although there are individual solutions that attempt to use battery power supply instead of wired power supply, the battery life of conventional battery modules conflicts with the intrinsic safety standards of mines. Ordinary large-capacity batteries are difficult to pass the coal mine safety certification, while batteries that meet the intrinsic safety requirements have limited capacity and cannot support the long-term stable operation of base stations. In addition, frequent battery replacement not only increases maintenance costs, but also may cause positioning data loss due to equipment power failure, forming a safety hazard. Therefore, on the premise of maintaining positioning accuracy and communication reliability, the research and development of low-power technologies for UWB positioning base stations applicable to coal mine roadway environments has become a bottleneck problem that the industry urgently needs to break through. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a low-power UWB precise positioning system for mines. The positioning base station generally adopts a low-power design, and the positioning terminal adaptively switches the working mode to solve the problem of difficult power supply for the positioning base station, enabling the positioning base station to automatically enter the sleep state when not working, reducing unnecessary energy consumption, so that the UWB precise positioning system can be popularized and applied in environments with difficult power supply, providing strong support for the intelligent construction of mines.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A low-power UWB precise positioning system for mines, comprising:

[0008] a central station for data processing and system management;

[0009] Multiple positioning base stations are divided into active power supply type and battery power supply type; the active power supply type positioning base station is connected to the industrial Ethernet ring network through the RS485 interface and adopts wired power supply; the battery power supply type positioning base station is wirelessly cascaded with adjacent base stations through the UWB module;

[0010] Multiple positioning terminals, carried by underground personnel, with UWB modules and rechargeable batteries;

[0011] Among them, all positioning base stations adopt a low-power sleep mechanism to work periodically: when scanning a positioning terminal, the positioning base station performs UWB ranging with the positioning terminal in a preset ranging time slot; all positioning base stations and positioning terminals work on a unified clock reference and transmit positioning data in an agreed communication time slot; the positioning terminal automatically switches the working mode according to the area where it is located, including active positioning mode or passive positioning mode, completes clock synchronization with the positioning base station and transmits the ranging results.

[0012] Preferably, the positioning base station includes a first low-power processor, a first UWB module and an RS485 interface, etc.;

[0013] The first low-power processor has a built-in low-power sleep mechanism and adopts dynamic voltage regulation technology to reduce the main frequency to standby mode during the sleep stage and wake up through a timer interrupt;

[0014] The first UWB module is used for wireless cascading and data transmission between positioning base stations, and UWB precise positioning and positioning data transmission between the positioning base station and the positioning terminal;

[0015] The RS485 interface is used to access the industrial Ethernet ring network and realize data communication with the central station;

[0016] Among them, the actively powered positioning base station communicates with the central station through the RS485 interface, the battery-powered positioning base station is wirelessly cascaded through the UWB module, and all positioning base stations support charging function.

[0017] Furthermore, when the positioning base station is actively powered, when there is a positioning terminal nearby, the positioning terminal is informed that this lane is a low-power UWB precise positioning system; when the positioning base station is battery-powered, it periodically scans the positioning terminal. If a positioning terminal exists, it completes the first clock synchronization with the positioning terminal, performs UWB ranging in the agreed ranging time slot, transmits positioning data in the specified communication time slot and updates the clock synchronization.

[0018] Preferably, the positioning terminal includes a second low-power processor, a second UWB module, a liquid crystal display screen, a triaxial sensor, a button, an LED, a buzzer, a vibration motor, etc.;

[0019] The second low-power processor has a built-in method for adaptively switching the working mode of the positioning terminal;

[0020] The second UWB module is used to access the positioning base station to achieve UWB precise positioning and data communication;

[0021] The triaxial sensor is used to detect the motion state of the positioning terminal, extend the sleep cycle when stationary, and shorten the cycle when moving to improve the positioning frequency;

[0022] The liquid crystal display screen is used to display the working state of the positioning terminal;

[0023] Among them, the positioning terminal periodically sleeps and sends access frames in the active positioning mode, and switches to the passive positioning mode after entering the system coverage range, keeps the UWB module working continuously, synchronizes the clock with the base station and completes ranging.

[0024] Furthermore, the positioning terminal has two working modes: (1) Active positioning mode, the positioning terminal periodically performs low-power sleep and UWB ranging; (2) Passive positioning mode, the UWB module of the positioning terminal always keeps working; in the active positioning mode, the positioning terminal periodically sends access frames, and when it enters the coverage range of the low-power UWB precise positioning system, it completes clock synchronization with the positioning base station and simultaneously switches to the passive positioning mode; in the passive positioning mode, the positioning terminal does not perform low-power sleep, the UWB module always keeps working, and completes UWB ranging with the positioning base station within the agreed ranging time slot, and at the same time sends the positioning data to the positioning base station.

[0025] Furthermore, the UWB precise positioning algorithm of this system is specifically as follows:

[0026] Linear roadway networking mode: Positioning base stations are deployed at intervals along the linear roadway, the coverage areas of adjacent positioning base stations overlap, and the positioning terminal determines its position by ranging through at least two positioning base stations;

[0027] Intersection networking mode: Positioning base stations are deployed in all directions at the intersection, and the positioning terminal realizes two-dimensional positioning by ranging through three positioning base stations.

[0028] Furthermore, the distance calculation formula between the positioning terminal and the positioning base station is:

[0029] D = T F *C

[0030] Where D is the UWB ranging value between the positioning terminal and the positioning base station; C is the speed of light, 3.0×10 8 m / s; T F is the flight time in the air between the positioning base station and the positioning terminal, and the expression is:

[0031] T F = ((T RR - T SP ) * (T RF - T SR ) - (T SF - T RR ) * (T SR - T RP )) / (T RF + T SF - T SP - T RP )

[0032] Where T SP is the transmission timestamp of the ranging request frame; T RP is the reception timestamp of the ranging request frame; T SR is the transmission timestamp of the ranging response frame; T RR is the reception timestamp of the ranging response frame; T SF is the transmission timestamp of the ranging data frame; T RF is the reception timestamp of the ranging data frame.

[0033] Furthermore, the low-power sleep mechanism of the positioning base station is specifically as follows: For the battery-powered positioning base station, the low-power sleep mechanism is adopted to reduce power consumption, work and enter low-power sleep periodically, and extend the battery working time; during the working stage, the positioning base station sends scan frames, initiates UWB ranging and transmits positioning data; during the low-power sleep stage, the positioning base station turns off the first UWB module, the first low-power processor enters the low-power mode, and the timer interrupt is set to wake up;

[0034] The battery-powered positioning base station has a working cycle of 5000 ms, which is divided into 100 50-ms time slots; within the first time slot (0 to 50 ms), the battery-powered positioning base stations wake up and work simultaneously, send scan frames and transmit positioning data; in other time slots, the positioning base station actively initiates UWB ranging to the positioning terminal; if there is no positioning terminal around, it enters low-power sleep;

[0035] In a low-power UWB precise positioning system, based on the clock of the active-powered positioning base station, when the positioning terminal switches from the active positioning mode to the passive positioning mode, it completes clock synchronization with the positioning base station and operates on the same clock scale; in the passive positioning mode, the positioning terminal receives the scan frame and reply response frame of the active-powered positioning base station, so that the active-powered positioning base station, the positioning terminal, and the active-powered positioning base station operate on the same clock scale.

[0036] The beneficial effects of the present invention are as follows:

[0037] 1) Aiming at the difficult power supply in the working face and roadway of high-gas and outburst mines, the low-power UWB precise positioning system designed by the present invention solves the problem of difficult power supply for the positioning base station, enabling the UWB precise positioning system of the present invention to be popularized and applied in environments with difficult power supply.

[0038] 2) According to the spatial characteristics of the mine roadway, the present invention proposes a roadway linear positioning algorithm and an intersection positioning algorithm. The positioning base station actively initiates UWB ranging, and the positioning terminal ranges with multiple adjacent positioning base stations simultaneously to achieve precise positioning of the mine roadway.

[0039] 3) The positioning base station of the present invention adopts a low-power design, is powered by a battery, and uses a low-power sleep mechanism to reduce energy consumption and extend the working time.

[0040] 4) The positioning terminal of the present invention has two working modes: active positioning mode and passive positioning mode, and switches the working mode in an adaptive manner to seamlessly access and exit the low-power UWB precise positioning system.

[0041] 5) The UWB precise positioning algorithm is adopted between the positioning terminal and the positioning base station of the present invention, improving the accuracy of personnel positioning.

[0042] Other advantages, objectives, and features of the present invention will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the following specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be described in detail and preferably with reference to the accompanying drawings, where:

[0044] Figure 1 is the architecture diagram of the mine low-power UWB precise positioning system provided by the embodiment of the present invention;

[0045] Figure 2 is the hardware design block diagram of the positioning base station;

[0046] Figure 3 is the working flowchart of the positioning base station (powered by mains);

[0047] Figure 4 is the working flowchart of the positioning base station (powered by battery);

[0048] Figure 5 is the block diagram of the hardware design of the positioning terminal;

[0049] Figure 6 is the schematic diagram of the adaptive switching of the working mode of the positioning terminal;

[0050] Figure 7 is the networking mode of the positioning base station;

[0051] Figure 8 is the schematic diagram of the TOF ranging principle;

[0052] Figure 9 is the schematic diagram of the position distribution of the linear roadway;

[0053] Figure 10 is the schematic diagram of the position distribution of the intersection;

[0054] Figure 11 is the schematic diagram of the working state of the positioning terminal. Specific implementation manners

[0055] The following uses specific specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0056] Among them, the attached drawings are only for illustrative purposes, showing only schematic diagrams, not physical diagrams, and should not be construed as limiting the present invention; in order to better illustrate the embodiments of the present invention, some components in the attached drawings will be omitted, enlarged or reduced, and do not represent the dimensions of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the attached drawings may be omitted.

[0057] In the drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and cannot be construed as a limitation of the present invention. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0058] Please refer to Figures 1 to 11 , an embodiment of the present invention provides a mine low-power UWB precise positioning system. As Figure 1 shown, this system uses UWB technology to achieve precise positioning of personnel and wireless transmission of positioning data, including a central station and software, positioning base stations, and positioning terminals. The positioning base station has 1 UWB channel and 1 RS485 interface. The positioning terminal has 1 UWB channel and has a large-capacity rechargeable battery, such as an information miner's lamp. The positioning base stations connected to the industrial Ethernet ring network are powered actively, and other positioning base stations are powered by batteries. All positioning base stations use a low-power sleep algorithm to work periodically and scan the positioning terminals. If there is a positioning terminal, the positioning base station performs UWB ranging with the positioning terminal within the agreed ranging time slot. Thereafter, all positioning base stations and positioning terminals work on a unified clock reference and transmit positioning data within the agreed time slot. When the positioning terminal enters the coverage range of the low-power UWB precise positioning system, it is always in a working state, and replies with the positioning base station clock information, ranging response, and ranging result.

[0059] 1. Design of the positioning base station

[0060] The positioning base station includes 1 low-power processor, 1 UWB module, 1 RS485 interface, etc. Its hardware design block diagram is as Figure 2 shown. The RS485 interface is used to access the industrial Ethernet ring network and communicate with the central station to achieve data communication. The UWB module is used for wireless cascading and data transmission between positioning base stations, and UWB precise positioning and positioning data transmission between the positioning base station and the positioning terminal. The positioning base stations connected to the industrial Ethernet ring network are powered actively, and other positioning base stations are powered by batteries. The low-power processor should meet the requirements of low-power design. The positioning base station has a charging function. After being fully charged, it is installed in the mine roadway to achieve complete coverage of the UWB signal.

[0061] There are two working modes for the positioning base station: (1) Active power supply, RS485 access to the industrial Ethernet ring network; (2) Battery power supply, UWB wireless cascading. When the positioning base station is actively powered, when there is a positioning terminal around, it notifies the positioning terminal that this roadway is a low-power UWB precise positioning system, and its working flow chart is as Figure 3 shown. When the positioning base station is battery-powered, it periodically scans for positioning terminals. If there is a positioning terminal, it completes the first clock synchronization with the positioning terminal, performs UWB ranging within the agreed ranging time slot, transmits positioning data within the specified communication time slot, and updates the clock synchronization. Its working flow chart is as Figure 4 shown.

[0062] 2. Design of the positioning terminal

[0063] The positioning terminal includes a low-power processor, a UWB module, a liquid crystal display screen, a three-axis sensor, a button, an LED, a buzzer, a vibration motor, etc. The UWB module is used to access the positioning base station to achieve UWB precise positioning and data communication. The liquid crystal display screen is used to display the working status of the positioning terminal.

[0064] There are two working modes for the positioning terminal: (1) Active positioning mode, the positioning terminal periodically performs low-power sleep and UWB ranging; (2) Passive positioning mode, the UWB module of the positioning terminal always remains working. In the active positioning mode, the positioning terminal periodically sends an access frame. When it enters the low-power UWB precise positioning system, it completes clock synchronization with the positioning base station and simultaneously switches to the passive positioning mode. In the passive positioning mode, the positioning terminal does not perform low-power sleep, the UWB module always remains working, completes UWB ranging with the positioning base station within the agreed ranging time slot, and simultaneously sends the positioning data to the positioning base station. The adaptive switching of the positioning terminal working mode is as Figure 6 shown.

[0065] 3. UWB precise positioning algorithm

[0066] In the low-power UWB precise positioning system, there are mainly two networking modes for the positioning base station: (1) Linear roadway networking; (2) Intersection networking. The networking mode of the positioning base station is as Figure 7 shown. In the linear roadway, a positioning base station is arranged at a certain distance interval. At the intersection, a positioning base station is arranged at each intersection. There needs to be complete overlapping coverage between adjacent positioning base stations to ensure that the positioning terminal can perform UWB ranging with multiple positioning base stations simultaneously.

[0067] The principle of UWB ranging between the positioning terminal and the positioning base station is as Figure 8 shown, and generally 3 communications are required: (1) Ranging request frame; (2) Ranging response frame; (3) Ranging data frame.

[0068] T F =((TRR -T SP )*(T RF -T SR )-(T SF -T RR )*(T SR -T RP )) / (T RF +T SF -T SP -T RP ) (1)

[0069] Among them, T SP is the transmission timestamp of the ranging request frame; T RP is the reception timestamp of the ranging request frame; T SR is the transmission timestamp of the ranging response frame; T RR is the reception timestamp of the ranging response frame; T SF is the transmission timestamp of the ranging data frame; T RF is the reception timestamp of the ranging data frame; T F is the flight time of the UWB wireless signal between the positioning terminal and the positioning base station.

[0070] The flight time T of the UWB signal between the positioning base station and the positioning terminal calculated using Equation (1) F has higher ranging accuracy and can significantly reduce the positioning error caused by crystal oscillator drift.

[0071] Therefore, the distance calculation formula between the positioning terminal and the positioning base station is:

[0072] D = T F *C (2)

[0073] Among them, D is the UWB ranging value between the positioning terminal and the positioning base station; C is the speed of light, 3.0×10 8 m / s.

[0074] For a linear roadway, the distance between positioning base station M and positioning base station N is D MN . As Figure 9 shown, there are three cases for the specific location of the positioning terminal:

[0075] (1) Case 1: The positioning terminal is in the middle of the coverage areas of positioning base station M and positioning base station N;

[0076] (2) Case 2: The positioning terminal is on the left side of the coverage areas of positioning base station M and positioning base station N;

[0077] (3) Case 3: The positioning terminal is on the right side of the coverage areas of positioning base station M and positioning base station N.

[0078] For intersections (such as three-way intersections), the distances between positioning base stations A, B, and C are all D AB 、D BC 、D AC . As Figure 10 shown, there are 4 cases for the specific location of the positioning terminal:

[0079] (1) Case 1: The positioning terminal is in the common coverage area of positioning base stations A, B, and C;

[0080] (2) Case 2: The positioning terminal is in the coverage area close to the direction of positioning base station A;

[0081] (3) Case 3: The positioning terminal is in the coverage area close to the direction of positioning base station B;

[0082] (4) Case 4: The positioning terminal is in the coverage area close to the direction of positioning base station C.

[0083] 4. Low-power sleep mechanism for positioning base stations

[0084] When the positioning base station is powered by a battery, a low-power sleep mechanism is adopted to reduce power consumption. It works and enters low-power sleep periodically to extend the battery working time. Its working state switching is as Figure 11 shown. During the working stage, the positioning base station sends scan frames, initiates UWB ranging, and transmits positioning data. During the low-power sleep stage, the positioning base station turns off the UWB module, the processor enters the low-power mode, and a timer interrupt is set to wake up.

[0085] In a low-power UWB precise positioning system, with the clock of the positioning base station (actively powered) as the reference, when the positioning terminal switches from the active positioning mode to the passive positioning mode, it synchronizes the clock with this positioning base station and works on the same clock scale. When the positioning terminal is in the passive positioning mode, it receives the scan frames of the positioning base station (battery-powered) and replies with response frames, so that the positioning base station (battery-powered), the positioning terminal, and the positioning base station (actively powered) work on the same clock scale.

[0086] The working cycle of the positioning base station (battery-powered) is 5000 ms, with 50 ms as a time slot, and there are 100 time slots in total. It is stipulated that within the first time slot (0 to 50 ms), the positioning base station (battery-powered) wakes up and works simultaneously, sending scan frames and transmitting positioning data. In other time slots, the positioning base station (battery-powered) actively initiates UWB ranging to the positioning terminal. If there is no positioning terminal around, it enters low-power sleep.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the present technical solution, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A low-power UWB precise positioning system for a mine, characterized in that, The system includes: A central station for data processing and system management; Multiple positioning base stations, divided into active power supply type and battery power supply type; the active power supply type positioning base station is connected to the industrial Ethernet ring network through the RS485 interface and is powered by wire; the battery power supply type positioning base station is wirelessly cascaded with adjacent base stations through the UWB module; Multiple positioning terminals, carried by underground personnel, with UWB modules and rechargeable batteries; Among them, all positioning base stations work periodically using a low-power sleep mechanism: when a positioning terminal is scanned, the positioning base station performs UWB ranging with the positioning terminal within a preset ranging time slot; all positioning base stations and positioning terminals work on a unified clock reference and transmit positioning data within a predefined communication time slot; the positioning terminal automatically switches the working mode according to the area it is in, including the active positioning mode or the passive positioning mode, and completes clock synchronization with the positioning base station and transmits the ranging result.

2. The low-power UWB precise positioning system according to claim 1, characterized in that The positioning base station includes a first low-power processor, a first UWB module, and an RS485 interface; The first low-power processor has a built-in low-power sleep mechanism; The first UWB module is used for wireless cascading and data transmission between positioning base stations, and UWB precise positioning and positioning data transmission between the positioning base station and the positioning terminal; The RS485 interface is used to access the industrial Ethernet ring network and realize data communication with the central station; Among them, the active power supply type positioning base station communicates with the central station through the RS485 interface, and the battery power supply type positioning base station is wirelessly cascaded through the UWB module, and all positioning base stations support the charging function.

3. The low-power UWB precise positioning system according to claim 1 or 2, characterized in that, When the positioning base station is powered by an active power supply, when there is a positioning terminal around, it notifies the positioning terminal that this roadway is a low-power UWB precise positioning system; when the positioning base station is powered by a battery, it periodically scans for positioning terminals. If a positioning terminal exists, it completes the first clock synchronization with the positioning terminal, performs UWB ranging within the predefined ranging time slot, transmits positioning data within the specified communication time slot, and updates the clock synchronization.

4. The low-power UWB precise positioning system according to claim 1, wherein The positioning terminal includes a second low-power processor, a second UWB module, a liquid crystal display screen, and a three-axis sensor; The second low-power processor has a built-in method for adaptive switching of the working mode of the positioning terminal; The second UWB module is used to access the positioning base station to achieve UWB precise positioning and data communication; The three-axis sensor is used to detect the motion state of the positioning terminal; The liquid crystal display screen is used to display the working state of the positioning terminal; Among them, the positioning terminal periodically sleeps and sends an access frame in the active positioning mode, and switches to the passive positioning mode after entering the system coverage area, keeps the UWB module working continuously, synchronizes the clock with the base station, and completes ranging.

5. The low-power UWB precise positioning system according to claim 1 or 4, characterized in that, The positioning terminal has two working modes: (1) Active positioning mode, in which the positioning terminal periodically performs low-power sleep and UWB ranging; (2) Passive positioning mode, in which the UWB module of the positioning terminal always remains working; In the active positioning mode, the positioning terminal periodically sends access frames. When it enters the coverage area of the low-power UWB precise positioning system, it completes clock synchronization with the positioning base station and simultaneously switches to the passive positioning mode; In the passive positioning mode, the positioning terminal does not perform low-power sleep, the UWB module always remains working, completes UWB ranging with the positioning base station within the agreed ranging time slot, and simultaneously sends the positioning data to the positioning base station.

6. The low-power UWB precise positioning system according to claim 1, characterized in that The UWB precise positioning algorithm of this system is specifically as follows: Linear roadway networking mode: Positioning base stations are deployed at intervals along the linear roadway, and the coverage areas of adjacent positioning base stations overlap. The positioning terminal determines its position by ranging through at least two positioning base stations; Intersection networking mode: Positioning base stations are deployed in all directions at the intersection. The positioning terminal realizes two-dimensional positioning by ranging through three positioning base stations.

7. The low-power UWB precise positioning system according to claim 6, characterized in that The distance calculation formula between the positioning terminal and the positioning base station is: D = T F *C Wherein, D is the UWB ranging value between the positioning terminal and the positioning base station; C is the speed of light; T F is the flight time in the air between the positioning base station and the positioning terminal, and the expression is: T F = ((T RR - T SP ) * (T RF - T SR ) - (T SF - T RR ) * (T SR - T RP )) / (T RF + T SF - T SP - T RP ) Among them, T SP is the transmission timestamp of the ranging request frame; T RP is the reception timestamp of the ranging request frame; T SR is the transmission timestamp of the ranging response frame; T RR is the reception timestamp of the ranging response frame; T SF is the transmission timestamp of the ranging data frame; T RF is the reception timestamp of the ranging data frame.

8. The low-power UWB precise positioning system according to claim 2, wherein The low-power sleep mechanism of the positioning base station is specifically as follows: For the battery-powered positioning base station, a low-power sleep mechanism is adopted to reduce power consumption, and it works and enters low-power sleep periodically; During the working stage, the positioning base station sends scanning frames, initiates UWB ranging, and transmits positioning data; During the low-power sleep stage, the positioning base station turns off the first UWB module, the first low-power processor enters the low-power mode, and a timer interrupt is set to wake up; The battery-powered positioning base station has a working cycle of 5000 ms, which is divided into 100 time slots of 50 ms; In the first time slot, the positioning base stations are simultaneously awakened to work, send scanning frames, and transmit positioning data; In other time slots, the positioning base station actively initiates UWB ranging to the positioning terminal; If there is no positioning terminal around, it will enter low-power sleep; In the low-power UWB precise positioning system, based on the clock of the active-powered positioning base station, when the positioning terminal switches from the active positioning mode to the passive positioning mode, it completes clock synchronization with this positioning base station and works on the same clock scale; When the positioning terminal is in the passive positioning mode, it receives the scanning frame of the active-powered positioning base station and replies with a response frame, so that the active-powered positioning base station, the positioning terminal, and the active-powered positioning base station work on the same clock scale.

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