UWB automobile digital key positioning system based on wireless transmission ToF distance

Abstract

The application relates to a UWB automobile digital key positioning system based on wireless transmission ToF distance, which comprises an automobile key with a UWB chip, a base station installed on an automobile and a host computer. The application has the beneficial effect that the UWB wireless information transmission method is used to replace the traditional CAN bus information transmission method, so that the material cost of CAN bus wiring and chips and the assembly cost of the UWB digital automobile key system are reduced. In addition, the application also designs and uses only one frame of data, solves the problem of poor stability of the traditional wireless information transmission, and uses a reliable transmission mechanism based on the stop-and-wait protocol to solve the problem of high data packet loss rate.

Description

Technical Field

[0001] This invention relates to the field of positioning system technology, and more specifically, to a UWB car digital key positioning system based on wireless transmission ToF distance. Background Technology

[0002] Ultra-wideband (UWB) technology is a wireless carrier communication technology with strong anti-interference capabilities, low power consumption, and high positioning accuracy, making it a preferred choice for automotive digital key positioning solutions. Currently, UWB base stations in automotive digital key positioning systems use a CAN bus (Controller Area Network) to transmit Time-of-Flight (ToF) ranging results, which are then aggregated to the host computer for car key positioning calculations. The disadvantages of this approach are: ① it requires CAN bus wiring harnesses to be installed in the vehicle, increasing assembly workload; ② it requires each UWB base station circuit to have a chip with CAN peripheral transmission capabilities, increasing chip costs. Furthermore, switching from CAN bus information transmission to wireless information transmission presents significant technical challenges, primarily due to poor information transmission stability and high data packet loss rates. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a UWB car digital key positioning system based on ToF (Time-of-Flight) wireless transmission distance. Unlike general wireless transmission systems, UWB is mainly used for positioning, with a limited number of bytes transmitted. Furthermore, the ranging data from each base station needs to be aggregated in real time during the positioning cycle. Therefore, this invention aims to solve the problem of how to use only one frame of data to carry a small amount of information to complete the real-time aggregation of ranging data from each base station, ensuring the accuracy of data transmission without reducing system stability.

[0004] In the first aspect, a UWB car digital key positioning system based on wireless transmission ToF distance is provided, including: a car key with a UWB chip, a base station installed in the car, and a host.

[0005] The base stations include a first base station, a second base station, a third base station, a fourth base station, and a fifth base station. The first base station to the fourth base station are respectively located on the front and rear sides of the vehicle, covering the left and right line-of-sight measurement of the vehicle. The fifth base station is located in the armrest box on the right side of the driver's seat. Each base station is at the same height from the ground, and each base station has its antenna arranged vertically upwards.

[0006] Secondly, a method for locating a UWB car digital key based on the ToF (Time-of-Flight) wireless transmission distance is provided, executed by the UWB car digital key locating system based on the ToF wireless transmission distance described in the first aspect, including:

[0007] S1. The car key initiates ranging communication and transmits frame data information with the base station; for each ranging communication, the base station and the host perform a reliable transmission based on the stop-and-wait protocol.

[0008] S2. The base station transmits the data frame information to the host with the UWB chip and attaches a data frame, which stores the ranging result of the previous moment. When the host receives the data frame information, it returns an acknowledgment character (ACK) or a negative acknowledgment character (NAK) to determine whether the data frame information needs to be retransmitted and sets a timeout retransmission.

[0009] S3. The host obtains the ranging value by parsing the data frame.

[0010] Preferably, in S1, when the car key initiates ranging communication, the car key saves the timestamp into the poll request frame and sends the poll request frame to each base station.

[0011] Preferably, in S1, the 0th byte of the poll request frame stores the frame index, the 1st byte of the poll request frame stores the sender and receiver, the 2nd byte of the poll request frame stores the base station sequence number, and the 3rd byte of the poll request frame stores the index of the data storage area.

[0012] As a preferred embodiment, in S2, after the first base station detects the empty poll frame, it saves the response timestamp and sends a Resp response frame to the car key and the host. After the remaining base stations detect the Resp response frame of the previous base station, they also send Resp response frames to the car key in turn. At the same time, the 4th to 7th bytes of the frame sent to the host save the ranging result calculated at the previous moment.

[0013] Preferably, in S2, the host detects the 0th byte of the data frame. If it is not repeated with the previous index, the data frame is successfully received and an acknowledgment character is returned. If it is repeated, it means that the data frame has been received, so the data frame is discarded and an acknowledgment character is returned. If the data frame fails to be received, a denial character is returned, indicating that the data frame needs to be sent again.

[0014] Preferably, in S3, the host calculates the coordinates by parsing the signal strength information in the data frame, performing mean filtering, and then transmitting the coordinates to the central controller.

[0015] As a preferred approach, in the data frame design, each base station first performs point-to-point ranging using the asymmetric double-side two-way ranging (ADS-TWR) method based on the saved timestamps, then performs mean filtering on the ranging results, and finally stores them in the data frame.

[0016] The beneficial effects of this invention are: This invention uses a UWB wireless information transmission method to replace the traditional CAN bus information transmission method, thereby reducing the material costs of CAN bus wiring harnesses and chips, and the assembly costs of the UWB digital car key system. Furthermore, this invention designs and uses only one frame of data, solving the problem of poor stability in traditional wireless information transmission, and uses a reliable transmission mechanism based on a stop-and-wait protocol to solve the problem of high data packet loss rate. Attached Figure Description

[0017] Figure 1 A schematic diagram of the structure of a UWB car digital key positioning system based on ToF wireless transmission distance provided by the present invention;

[0018] Figure 2 The system timing diagram for wireless transmission ToF distance provided by this invention;

[0019] Figure 3 This invention provides an information field diagram of the wireless transmission ToF distance.

[0020] Explanation of the reference numerals in the attached diagram: First base station 0, Second base station 1, Third base station 2, Fourth base station 3, Fifth base station 4. Detailed Implementation

[0021] The present invention will be further described below with reference to embodiments. The description of the embodiments below is only for the purpose of helping to understand the present invention. It should be noted that those skilled in the art can make several modifications to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0022] Example 1:

[0023] A UWB car digital key positioning system based on ToF wireless transmission distance, such as Figure 1 As shown, it includes: a car key with a UWB chip, a base station installed in the car, and a host;

[0024] The system includes five base stations: a first base station 0, a second base station 1, a third base station 2, a fourth base station 3, and a fifth base station 4. Base stations 0 through 3 are located on either side of the front and rear of the vehicle, respectively, covering left and right sight distance measurement. Base station 4 is located in the armrest box on the right side of the driver's seat. All base stations are at the same height from the ground (e.g., 0.6m), and their antennas are vertically upwards. The car key is responsible for establishing distance measurement communication; the base stations and the car key transmit data; the main unit is located in the armrest box on the right side of the driver's seat, listening to the data frames transmitted by the base stations and calculating the results.

[0025] Example 2:

[0026] like Figure 2 and Figure 3 As shown, a UWB car digital key positioning method based on ToF wireless transmission distance includes:

[0027] S1. The car key initiates ranging communication and transmits frame data information with the base station. Each device saves the sending and receiving timestamps of each message. For each ranging communication, the base station and the host perform a reliable transmission based on the stop-and-wait protocol to ensure data accuracy.

[0028] S2. The base station transmits data frame information to a host equipped with a UWB chip and attaches a data frame containing the ranging result from the previous moment. Upon receiving the data frame information, the host returns an acknowledgment or denial character to determine whether the data frame information needs to be retransmitted. A timeout retransmission is also set to prevent the base station from waiting indefinitely for the host to return an acknowledgment character. This improves channel utilization and ensures the accuracy of data transmission.

[0029] S3. The host obtains the ranging value by parsing the data frame, which replaces the effect of ToF ranging transmitted by the CAN bus.

[0030] In S3, the host calculates the coordinates by parsing information such as timestamps and signal strength in the data frames, performing mean filtering, and then transmitting the coordinates to the central controller.

[0031] In the data frame design, each base station first performs point-to-point ranging using an asymmetric bilateral bidirectional ranging method based on the saved timestamps. Then, the ranging results are subjected to mean filtering and finally stored in the data frame.

[0032] Example 3:

[0033] 1) The car key initiates ranging communication, saves the timestamp in the poll request frame, and sends it to each base station as follows: Figure 3 The poll frame information contains the following: byte 0 stores the frame index (AMSI frame flag index offset), byte 1 stores the sender and receiver (AMUI frame sender and receiver UWBID index offset), byte 2 stores the base station sequence number (AMSI ranging sequence number index offset), and byte 3 stores the index of the data area (AMDSI data area index offset).

[0034] 2) After the first base station detects a poll empty frame, it saves the response timestamp and sends a message to the car key and the host computer, such as... Figure 3 The remaining base stations, after listening to the Resp frame of the previous base station, also send Resp frames to the car key in sequence. At the same time, the 4th to 7th bytes of the frame sent to the host store the ranging result calculated at the previous moment (LTD previous moment calculation data) to replace the CAN bus transmission.

[0035] 3) The car key listens to the Resp frames of each base station. If the data frame is successfully received, it checks the index of byte 0 of the frame. If it is not the same as the previous index, the reception is successful, and an ACK signal is returned. If it is the same, it means that the packet has already been received, so the packet is discarded, and an ACK signal is returned. If the data frame reception fails, an NCK signal is returned, indicating that the data frame needs to be sent again. After successfully receiving the data frame, the timestamp is saved again, and a Final data frame is sent to the base station. Bytes 0-11 of the Final frame data segment store the timestamps of the previous three ranging communications, and bytes 12-15 store the signal strength data.

[0036] 4) The base station detects the Final data frame. Bytes 0-14 of the Final data segment store the timestamps of the previous three ranging communications, and byte 15 stores the signal strength data. The base station uses the timestamps of the previous three ranging communications to perform point-to-point ranging using the ADS-TWR method and performs filtering operations such as mean filtering, waiting for the next transmission.

[0037] 5) The host listens to the Resp response frame from the base station, parses the data frame timestamp, signal strength and other information, calculates the distance, and then transmits the calculated coordinate results to the central controller after passing mean filtering and Kalman filtering.

Claims

1. A method for locating a UWB car digital key based on ToF wireless transmission distance, characterized in that, The positioning is performed by a UWB car digital key system based on wireless transmission ToF distance. The system includes: a car key with a UWB chip, a base station installed in the car, and a host. The base stations include a first base station (0), a second base station (1), a third base station (2), a fourth base station (3), and a fifth base station (4). The first base station (0) to the fourth base station (3) are respectively located on both sides of the front and rear of the vehicle, covering the left and right sight distance measurement of the vehicle. The fifth base station (4) is located in the armrest box on the right side of the driver's seat of the vehicle. Each base station is at the same height from the ground, and each base station keeps its antenna vertically upward. The methods include: S1. The car key initiates ranging communication and transmits frame data information with the base station; each ranging communication involves a reliable transmission between the base station and the host based on a stop-and-wait protocol; in S1, when the car key initiates ranging communication, the car key saves the timestamp into the poll request frame and sends the poll request frame to each base station; the 0th byte of the poll request frame stores the frame index, the 1st byte stores the sender and receiver, the 2nd byte stores the base station sequence number, and the 3rd byte stores the index of the data storage area; S2. The base station transmits the data frame information to the host with the UWB chip and attaches a data frame containing the ranging result from the previous moment. Upon receiving the data frame, the host returns an acknowledgment or denial character to determine whether the data frame needs to be retransmitted and sets a timeout for retransmission. In S2, the first base station, after detecting a poll empty frame, saves the response timestamp and sends a Resp response frame to the car key and the host. The remaining base stations, after detecting the Resp response frame from the previous base station, also send Resp response frames to the car key sequentially. Bytes 4-7 of the frame sent to the host contain the ranging result calculated from the previous moment. The host checks the 0th byte of the data frame. If it is not a duplicate of the previous index, the data frame is successfully received, and an acknowledgment character is returned. If it is a duplicate, it indicates that the data frame has already been received, so the data frame is discarded, and an acknowledgment character is returned. If the data frame reception fails, a denial character is returned, indicating that the data frame needs to be retransmitted. S3. The host obtains the ranging value by parsing the data frame. In S3, the host calculates the coordinates by parsing the signal strength information in the data frame, performing mean filtering, and then transmitting the coordinates to the central controller.

2. The UWB car digital key positioning method based on ToF wireless transmission distance according to claim 1, characterized in that, In the data frame design, each base station first performs point-to-point ranging using an asymmetric bilateral bidirectional ranging method based on the saved timestamps. Then, the ranging results are subjected to mean filtering and finally stored in the data frame.

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