A TDOA scheduling system and method based on ultra-wideband positioning

Abstract

The present invention discloses a TDOA scheduling system and method based on ultra-wideband positioning, wherein the scheduling system includes a synchronous base station, at least four ordinary base stations, a data transfer module, a PC terminal, and a mobile tag. The synchronous base station is used to periodically broadcast synchronization messages; the ordinary base station synchronizes the local clock with the synchronous base station time; the mobile tag is set on the positioning target and broadcasts the positioning request; the ordinary base station sends the positioning request time information to the PC terminal via the data transfer module, and the PC terminal uses the TDOA positioning algorithm to calculate the position of the mobile tag according to the positioning request time information. The system realizes the dynamic scheduling of the entire indoor positioning by determining the maximum number of messages allowed to be sent by the mobile tag within the transmission time and the range of the number of positioning transmissions allowed by the synchronous base station within the synchronous message broadcast period, thereby improving the scheduling efficiency when the total capacity of the system is limited.

Description

Technical Field

[0001] The present invention belongs to the technical field of indoor positioning, and in particular relates to a TDOA scheduling system and a scheduling method based on ultra-wideband positioning. Background Art

[0002] Ultra-wideband systems have great potential for robotics and automation due to their low deployment costs and few constraints. Compared to optical motion capture systems, laser scanners or structured light-based methods, they do not require special lighting conditions to operate properly. Therefore, recent research focuses on using UWB systems for indoor robot localization. However, the main way to successfully localize is by using two-way ranging (TWR), where two independent nodes obtain the range of each other by measuring the round-trip time of packet exchange. However, the localization results obtained with this simple method are often wrong because of clock drift during the exchange. Therefore, symmetric (asymmetric) bilateral two-way ranging (SDS-TWR) adds another packet to the exchange and uses this symmetry in processing time to eliminate the corresponding measurement errors. Other methods use multiple confirmations to calculate the relevant drift and compensate accordingly.

[0003] While all TWR-based approaches have the capability to serve the range measurement requirements of positioning, the linear relationship between channel utilization and energy consumption with the number of anchors used leads to significant issues when considering multi-user, battery-powered applications. There is a need for research involving highly scalable positioning using infrastructure transmission time difference of arrival (T-TDOA). Although the scalability of the topology is greatly improved with the increase in the number of users, similar to the Global Navigation Satellite System (GNSS), the energy consumption of the mobile nodes also increases with the increase in base stations. Therefore, there is an urgent need for a lightweight scheduling protocol that can seamlessly integrate the wireless clock synchronization required for normal operation. Summary of the invention

[0004] Purpose of the invention: In view of the problems existing in the prior art, the present invention provides a TDOA scheduling system and scheduling method based on ultra-wideband positioning.

[0005] Technical solution: The present invention adopts the following technical solution:

[0006] A TDOA scheduling system based on ultra-wideband positioning, comprising: a synchronous base station, at least four ordinary base stations, a data transfer module, a PC terminal, and one or more mobile tags;

[0007] The synchronous base station, the common base station, the data transfer module, and the mobile tag communicate with each other via a wireless connection, and the data transfer module communicates with the PC via a wired connection;

[0008] The synchronization base station is used to periodically broadcast synchronization messages; the common base station synchronizes the local clock with the synchronization base station time in the synchronization message according to the synchronization message;

[0009] The mobile tag is set on the positioning target and broadcasts a positioning request. The ordinary base station sends the positioning request time information to the PC via the data transfer module based on the received positioning request. The PC uses the TDOA positioning algorithm to calculate the position of the mobile tag based on the positioning request time information sent by each ordinary base station.

[0010] Preferably, the synchronization base station is based on T m The synchronization message is broadcast periodically; the synchronization message carries the synchronization base station ID and the synchronization base station time;

[0011] Preferably, the wireless connection for communication adopts Ultra Wide Band (UWB) communication technology.

[0012] The scheduling system will be T m The time interval is divided into N s subintervals, each subinterval is divided into n durations of t s slots, including n1 random access slots and n2 scheduled access slots; n = n1 + n2.

[0013] Preferably, the mobile tag waits for a time τ after receiving the synchronization message and then broadcasts a positioning request; the waiting time τ is calculated as: τ=ln[U(0,1)]n1t s , U(0,1) is a random number between (0,1);

[0014] The positioning request carries the ID of the mobile tag.

[0015] The present invention also provides a scheduling method using the above-mentioned TDOA scheduling system based on ultra-wideband positioning, comprising:

[0016] Step 1: Synchronize the base station with T m The synchronization message is broadcast periodically; the synchronization message carries the synchronization base station ID and the synchronization base station time;

[0017] The duration is T m The time interval is divided into N s subintervals, each subinterval is divided into n durations of t s slots, including n1 random access slots and n2 scheduled access slots;

[0018] Step 2: The mobile tag waits for time t after receiving the synchronization message aThen broadcast the positioning request; the waiting time τ is calculated using the random access time: τ = ln[U(0,1)]n1t s , U(0,1) is a random number between (0,1);

[0019] The positioning request carries the ID of the mobile tag;

[0020] After receiving the synchronization message, the common base station synchronizes the local clock with the synchronization base station time in the synchronization message;

[0021] Step 3: After receiving the positioning request, the synchronization base station sends the positioning request to the PC via the data transfer module; after verifying the sample data, the PC searches the database according to the mobile tag ID carried in the positioning request, determines the offset of the mobile tag, and sends it to the synchronization base station via the data transfer module;

[0022] Step 4: The synchronous base station broadcasts a positioning request response, which carries the mobile tag ID and the mobile tag offset λ. o ;

[0023] Step 5: The mobile tag receives the positioning request response. If the mobile tag ID carried in the response is consistent with its own ID, the positioning time offset Δt(k) is calculated: Δt(k) = ((2 α N s )k+λ o )t s ; Where k is the positioning information serial number, α is the sending frequency of the mobile tag;

[0024] Constructing and broadcasting positioning information, wherein the positioning information carries a positioning time offset Δt(k);

[0025] Step 6: Move the tag according to the arrival time t of the synchronization message sy-1 The arrival time of the positioning request response is t sy The difference between the clock and the synchronization base station is fixed at the clock deviation ratio ε s Estimated value of To calculate the transmission time compensation

[0026]

[0027] Step 7: The mobile tag compensates for the transmission time. The compensated transmission time is

[0028] Step 8: Calculate the maximum number of messages S that the mobile tag is allowed to send within the transmission time max :

[0029]

[0030] in t p is the packet duration, slot duration t s and time t p The difference can determine the remaining duration in the slot, allowing the mobile tag to send continuously within the time γ after synchronization. It is a floor rounding operation;

[0031] Calculate the synchronization base station in the synchronization message broadcast period T m The number of positioning transmissions allowed within n t The range is: n t ≤S max ;

[0032] Step 9: The PC uses the TDOA positioning algorithm to calculate the position of the mobile tag corresponding to the mobile tag ID carried in the positioning request according to the positioning request time information forwarded by the ordinary base station.

[0033] Preferably, the PC end verifies the sample data in step 3 to verify the following contents:

[0034] Verify that the period of the positioning request sent by the synchronization base station is consistent with T m Is the difference within the allowable range?

[0035] Verify whether the difference between the number of sub-interval slots and n in the positioning request sent by the synchronization base station is within the allowable range;

[0036] Verify that the duration of each slot in the subinterval of the positioning request sent by the synchronous base station is consistent with t s Is the difference within the allowable range?

[0037] Preferably, the database in step 3 is mainly indexed by mobile tag ID, in which the configuration and priority of each mobile tag are pre-stored.

[0038] Beneficial effects: The TDOA scheduling system and scheduling method based on ultra-wideband positioning disclosed in the present invention automatically generates a response in the upcoming synchronization message by the synchronization base station within a synchronization period before the transmission of the positioning information; if received, the mobile tag can update its estimated transmission time compensation and continue to send without having to send and receive another message; if lost, the mobile tag must trigger a new positioning request. The synchronization response can be sent multiple times before the end of the allowed transmission to avoid positioning interruptions during the retransmission of the positioning request, thereby ensuring the real-time capability of the system. The synchronization base station periodically broadcasts the synchronization message to synchronize the clocks of each ordinary base station, thereby improving the accuracy of the TDOA algorithm in calculating the position of the mobile tag; by setting the duration of T mThe time interval is divided into subintervals, each subinterval is divided into slots, and the mobile tag calculates the waiting time for sending the positioning request, the positioning time offset and the transmission time compensation according to the division of the slots, thereby determining the maximum number of messages allowed to be sent by the mobile tag within the transmission time and the range of the number of positioning transmissions allowed by the synchronization base station within the synchronization message broadcast cycle, thereby realizing dynamic scheduling of the entire indoor positioning system and improving the scheduling efficiency when the total capacity of the system is limited. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The present invention discloses a schematic diagram of the composition of a TDOA scheduling system based on ultra-wideband positioning;

[0040] Figure 2 It is a schematic diagram of the cooperation process of various components of the TDOA scheduling system based on ultra-wideband positioning;

[0041] Figure 3 The present invention discloses a flow chart of a TDOA scheduling method based on ultra-wideband positioning. DETAILED DESCRIPTION

[0042] The present invention is further explained below in conjunction with the accompanying drawings and specific implementation methods.

[0043] like Figure 1 As shown, the present invention discloses a TDOA scheduling system based on ultra-wideband positioning, including: a synchronous base station 1, four ordinary base stations B1-B4, a data transfer module 2, a PC terminal 3, and a mobile tag 4;

[0044] The synchronous base station, the common base station, the data transfer module, and the mobile tag are all provided with antennas, and communicate via wireless connection. The data transfer module communicates with the PC via a wired connection. In this embodiment, the two communicate via a serial port.

[0045] The synchronization base station is used to periodically broadcast synchronization messages; the common base station synchronizes the local clock with the synchronization base station time in the synchronization message according to the synchronization message;

[0046] The mobile tag is set on the positioning target and broadcasts a positioning request. The ordinary base station sends the positioning request time information to the PC via the data transfer module based on the received positioning request. The PC uses the TDOA positioning algorithm to calculate the position of the mobile tag based on the positioning request time information sent by each ordinary base station.

[0047] In specific applications, there may be multiple mobile tags according to the number of positioning targets. Each mobile tag has a unique identifier ID, and different mobile tags are distinguished by different IDs.

[0048] Synchronous base station with T mis a periodic broadcast synchronization message; the synchronization message carries the synchronization base station ID and synchronization base station time; the duration is T m The time interval is divided into N s subintervals, each subinterval is divided into n durations of t s slots, including n1 random access slots and n2 scheduled access slots, n = n1 + n2.

[0049] After receiving the synchronization message, the mobile tag waits for a period of time τ before broadcasting a positioning request; the waiting time τ is calculated as: τ = ln[U(0,1)]n1t s , U(0,1) is a random number between (0,1);

[0050] The positioning request carries the ID of the mobile tag.

[0051] During the synchronization cycle, the mobile tag performs time compensation. The collaboration process between the components is as follows: Figure 2 shown.

[0052] The scheduling method of the TDOA scheduling system based on ultra-wideband positioning is as follows: Figure 3 As shown, including:

[0053] Step 1: Synchronize the base station with T m The synchronization message is broadcast periodically; the synchronization message carries the synchronization base station ID and the synchronization base station time;

[0054] The duration is T m The time interval is divided into N s subintervals, each subinterval is divided into n durations of t s slots, including n1 random access slots and n2 scheduled access slots, n = n1 + n2.

[0055] Step 2: After receiving the synchronization message, the mobile tag waits for a period of time τ and then broadcasts a positioning request; the calculation of the waiting time τ is: τ=ln[U(0,1)]n1t s , U(0,1) is a random number between (0,1);

[0056] The positioning request carries the ID of the mobile tag;

[0057] After receiving the synchronization message, the common base station synchronizes the local clock with the synchronization base station time in the synchronization message;

[0058] Step 3: After receiving the positioning request, the synchronization base station sends the positioning request to the PC via the data transfer module; after verifying the sample data, the PC searches the database according to the mobile tag ID carried in the positioning request, determines the offset of the mobile tag, and sends it to the synchronization base station via the data transfer module;

[0059] The PC-side verification sample is to remove irregular messages. In this embodiment, the PC-side verification sample data verifies the following contents:

[0060] Verify that the period of the positioning request sent by the synchronization base station is consistent with T m Is the difference within the allowable range?

[0061] Verify whether the difference between the number of sub-interval slots and n in the positioning request sent by the synchronization base station is within the allowable range;

[0062] Verify that the duration of each slot in the subinterval of the positioning request sent by the synchronous base station is consistent with t s Is the difference within the allowable range?

[0063] The PC-side database uses the mobile tag ID as the main index, which stores the configuration and priority of each mobile tag in advance. After retrieving the corresponding mobile tag through the mobile tag ID, its offset can be obtained.

[0064] Step 4: The synchronous base station broadcasts a positioning request response, which carries the mobile tag ID and the mobile tag offset λ. o ;

[0065] Step 5: The mobile tag receives the positioning request response. If the mobile tag ID carried in the response is consistent with its own ID, the positioning time offset Δt(k) is calculated: Δt(k) = ((2 α N s )k+λ o )t s ; Where k is the positioning information serial number, α is the sending frequency of the mobile tag;

[0066] Constructing and broadcasting positioning information, wherein the positioning information carries a positioning time offset Δt(k);

[0067] Step 6: Move the tag according to the arrival time t of the synchronization message sy-1 The arrival time of the positioning request response is t sy The difference between the clock and the synchronization base station is fixed at the clock deviation ratio ε s Estimated value of To calculate the transmission time compensation

[0068]

[0069]

[0070] Step 7: The mobile tag compensates for the transmission time. The compensated transmission time is Where T mThe period for broadcasting synchronization messages for synchronization base stations;

[0071] Step 8: Calculate the maximum number of messages S that the mobile tag is allowed to send within the transmission time max :

[0072]

[0073] in τ p is the packet duration, It is a floor rounding operation;

[0074] Calculate the synchronization base station in the synchronization message broadcast period T m The number of positioning transmissions allowed within n t The range is: n t ≤S max ;

[0075] Step 9: The PC uses the TDOA positioning algorithm to calculate the position of the mobile tag corresponding to the mobile tag ID carried in the positioning request according to the positioning request time information forwarded by the ordinary base station.

Claims

1. A TDOA scheduling system based on ultra-wideband positioning, characterized in that: include: One synchronous base station, at least four common base stations, data transfer module, PC terminal, one or more mobile tags; The synchronous base station, the common base station, the data transfer module, and the mobile tag communicate with each other via a wireless connection, and the data transfer module communicates with the PC via a wired connection; The synchronization base station is used to periodically broadcast synchronization messages; The common base station synchronizes the local clock with the synchronization base station time in the synchronization message according to the synchronization message; The mobile tag is set on the positioning target and broadcasts the positioning request. The ordinary base station sends the positioning request time information to the PC via the data transfer module according to the received positioning request. The PC adopts the TDOA positioning algorithm to calculate the position of the mobile tag according to the positioning request time information sent by each ordinary base station. The synchronous base station is T m The synchronization message is broadcast periodically; the synchronization message carries the synchronization base station ID and the synchronization base station time; The duration is T m The time interval is divided into N s subintervals, each subinterval is divided into n durations of t s slots, including n1 random access slots and n2 scheduled access slots; n = n1 + n2; After receiving the synchronization message, the mobile tag waits for a period of time τ before broadcasting a positioning request; the waiting time τ is calculated using the random access time: τ = ln[U(0,1)]n1t s , U(0,1) is a random number between (0,1); The positioning request carries the ID of the mobile tag; After receiving the synchronization message, the common base station synchronizes the local clock with the synchronization base station time in the synchronization message; After receiving the positioning request, the synchronization base station sends the positioning request to the PC via the data transfer module; After verifying the sample data, the PC retrieves the database according to the mobile tag ID carried in the positioning request, determines the offset of the mobile tag, and sends it to the synchronization base station via the data transfer module; The synchronous base station broadcasts a positioning request response, and the positioning request response carries the mobile tag ID and the mobile tag offset λ o ; The mobile tag receives the positioning request response, and if the mobile tag ID carried therein is consistent with its own ID, the positioning time offset Δt(k) is calculated: Δt(k)=((2 α N s )k+λ o )t s ; Where k is the positioning information serial number, α is the sending frequency of the mobile tag; Constructing and broadcasting positioning information, wherein the positioning information carries a positioning time offset Δt(k); The mobile tag is based on the arrival time t of the synchronization message sy-1 The arrival time of the positioning request response is t sy The difference between the clock and the synchronization base station is fixed at the clock deviation ratio ε s Estimated value of Calculating Transit Time Compensation The mobile tag compensates the transmission time, and the compensated transmission time is Where T m The period for broadcasting synchronization messages for synchronization base stations; Calculate the maximum number of messages S that the mobile tag is allowed to send within the transmission time max : in t p is the packet duration, It is a floor rounding operation; Calculate the synchronization base station in the synchronization message broadcast period T m The number of positioning transmissions allowed within n t The range is: n t ≤S max ; The PC side uses the TDOA positioning algorithm to calculate the position of the mobile tag corresponding to the mobile tag ID carried in the positioning request according to the positioning request time information forwarded by the ordinary base station.

2. The TDOA scheduling system according to claim 1, characterized in that: The wireless connection for communication adopts ultra-wideband communication technology.

3. The scheduling method of the TDOA scheduling system based on ultra-wideband positioning according to any one of claims 1 to 2, characterized in that: After receiving the positioning request, the synchronization base station sends the positioning request to the PC via the data transfer module; after verifying the sample data, the PC searches the database according to the mobile tag ID carried in the positioning request, determines the offset of the mobile tag, and sends it to the synchronization base station via the data transfer module; wherein, the PC verifies the sample data to verify the following contents: Verify that the period of the positioning request sent by the synchronization base station is consistent with T m Is the difference within the allowable range? Verify whether the difference between the number of sub-interval slots and n in the positioning request sent by the synchronization base station is within the allowable range; Verify that the duration of each slot in the subinterval of the positioning request sent by the synchronous base station is consistent with t s Is the difference within the allowable range? 4. The TDOA scheduling method based on ultra-wideband positioning according to claim 3, characterized in that: The database is mainly indexed by the mobile tag ID, in which the configuration and priority of each mobile tag are pre-stored.

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