A system time synchronization device for rescue teams based on the openEuler system

Abstract

The present invention relates to a system time synchronization device for a rescue fleet based on the openEuler system, wherein each vehicle includes Beidou, time-keeping timing, a vehicle-mounted node and a 5G‑CPE module; the Beidou module transmits the received Beidou astronomical time to the time-keeping timing module; the time-keeping timing module receives the Beidou astronomical time; the vehicle-mounted node module includes multiple vehicle-mounted terminals and multiple computing and processing modules, all of which adopt the openEuler operating system; a monitoring node is selected from all online vehicle-mounted node modules of each rescue vehicle, and the monitoring node synchronizes the time of the vehicle-mounted node module based on the working status of the time-keeping timing module and the validity of calendar information of the vehicle using high or low precision PTP time synchronization, local autonomous time or manual time synchronization mode; the 5G‑CPE module realizes the networking of the fleet workshops, and the networking of each rescue vehicle with the command center module; the command center module assigns a unique ID to the rescue vehicle to determine the lead vehicle and the following vehicle.

Description

Technical Field

[0001] The present invention relates to the technical field of time synchronization of an electronic information system of a rescue vehicle team, and in particular to a system time synchronization device for a rescue vehicle team based on an openEuler system. Background Art

[0002] In modern rescue operations, the coordinated operation of rescue teams is crucial. Rescue teams typically consist of multiple vehicles with different functions, such as ambulances, fire trucks, and engineering rescue vehicles. To ensure efficient and orderly rescue operations, communication and time synchronization between vehicles within the rescue team and between vehicles and the command center are extremely critical.

[0003] Traditional rescue fleet electronic information systems based on domestic software and hardware have poor time synchronization capabilities and the following major flaws:

[0004] In traditional domestic rescue fleet electronic information systems, the Beidou module only synchronizes high-precision TOD (Time of Day) with on-board communication equipment. The Beidou module uses a low-precision time synchronization method to transmit Beidou astronomical time data to electronic devices such as on-board computers and terminals via internal buses such as CAN (Controller Area Network) or Gigabit Ethernet. These electronic devices then set the received Beidou astronomical time as local time, with time synchronization accuracy at the millisecond or even second level. This method no longer meets the time synchronization requirements of the networked electronic system architecture of rescue fleets, nor can it meet the requirements of multi-vehicle and unmanned vehicle collaborative rescue operations in complex environments.

[0005] The time synchronization strategy is single. Although the traditional rescue team electronic information system based on domestic software and hardware environment has replaced the US GPS technology (Global Positioning System) with the domestic Beidou satellite navigation system technology to complete the domestic replacement, it only uses a single clock source (Beidou astronomical time). Local time synchronization relies on Beidou satellite astronomical time information. When the vehicle is in a state of poor Beidou satellite signal and the on-board timing module is not working properly, the time synchronization of various devices in the system cannot be completed, affecting the vehicle system information transmission and integration, and cannot meet the actual operational needs of the rescue team.

[0006] Time synchronization accuracy is poor. In traditional rescue fleet electronic information systems based on domestically produced hardware and software, the BeiDou module only synchronizes time with on-board communication equipment (e.g., onboard radios) for high-precision time synchronization (TOD). The BeiDou module uses low-precision time synchronization to transmit BeiDou astronomical time data via on-board buses such as CAN (Controller Area Network) or Gigabit Ethernet to electronic devices such as on-board computers and terminals. These devices then set the received BeiDou astronomical time as local time, resulting in time synchronization accuracy at the millisecond or even second level. This method no longer meets the time synchronization requirements of the networked electronic system architecture of rescue fleets, nor can it meet the requirements for multi-vehicle and unmanned vehicle collaborative rescue operations in complex environments. Summary of the Invention

[0007] In view of the above analysis, an embodiment of the present invention aims to provide a system time synchronization device for a rescue fleet based on the openEuler system, so as to solve the technical problem of how to synchronize the time of on-board computers and on-board terminals in a rescue fleet based on domestic software and hardware platforms, improve the time synchronization accuracy, and provide multiple time synchronization strategies to meet the time requirements in different scenarios.

[0008] The present invention provides a system time synchronization device for a rescue team based on the openEuler system, comprising the following steps:

[0009] Each rescue vehicle includes a BeiDou module, a timekeeping timing module, an on-board node module, and a 5G-CPE module;

[0010] The Beidou module is used to transfer the Beidou astronomical time TOD obtained from the received Beidou satellite signal to the timekeeping timing module;

[0011] The timekeeping and timing module is used to receive the Beidou astronomical time;

[0012] The on-board node module includes multiple on-board terminals and multiple computing and processing modules in an on-board computer; the on-board terminals and computing and processing modules all use the domestic openEuler operating system and domestic chips; wherein, a monitoring node is selected from all online on-board node modules in each rescue vehicle, and the monitoring node synchronizes the system time of the on-board node modules of the rescue team based on the working status of the timekeeping and timing module of the vehicle and the validity of the calendar information, using high-precision PTP time synchronization, low-precision PTP time synchronization, local autonomous time synchronization or local manual time synchronization mode;

[0013] The 5G-CPE module is used to realize the networking of all vehicles in the rescue team, as well as the networking of each rescue vehicle with the command center module;

[0014] The command center module assigns a unique vehicle ID to each rescue vehicle in the rescue team and identifies the lead vehicle and the following vehicle.

[0015] Furthermore, the onboard computer further includes:

[0016] A power module, used to supply power to the onboard computer;

[0017] A network switching module is used to provide an Ethernet connection for each rescue vehicle and to connect with the 5G-CPE module.

[0018] Furthermore, each vehicle-mounted node module, Beidou module and time-keeping timing module in each rescue vehicle in the rescue fleet are connected via Ethernet;

[0019] Each rescue vehicle, as well as each rescue vehicle and the command center module are connected to a 5G cellular network based on the 5G-CPE module.

[0020] Furthermore, the time synchronization priority of all onboard node modules of the vehicle is set, and the IP address, CPU main frequency, time synchronization priority and MAC address ID of each onboard node module of the vehicle are multicasted into the node resource pool via UDP;

[0021] Each rescue vehicle selects a monitoring node from each onboard node module based on the CPU main frequency and MAC address ID in the node resource pool. The monitoring node establishes communication with the timekeeping and timing module to determine the working status of the timekeeping and timing module and the validity status of the current calendar information.

[0022] The monitoring node of each rescue vehicle determines the time synchronization mode based on the working status of the timekeeping and timing module and the valid status of the current calendar information, and synchronizes the system time of each vehicle-mounted node module in the rescue fleet based on the time synchronization mode and the time synchronization priority.

[0023] Furthermore, if the working status of the timekeeping and timing modules in all rescue vehicles in the rescue team are synchronized or the working status of the timekeeping and timing modules in some rescue vehicles is synchronized, and the current calendar information is valid, each rescue vehicle adopts the high-precision PTP time synchronization mode to perform high-precision time synchronization on each vehicle-mounted node module based on the timekeeping and timing module clock source;

[0024] If the working status of the timekeeping and timing module is synchronizing, timekeeping or RTC timing, and the current calendar information is valid, a vehicle is selected based on the workshop 5G cellular network of the 5G-CPE module to obtain a reference vehicle, and a low-precision PTP time synchronization mode is used to perform low-precision time synchronization on the system time of the on-board node modules in the rescue team based on the clock source of the timekeeping and timing module of the reference vehicle;

[0025] If the working states of the timekeeping and timing modules of all vehicles in the rescue convoy are asynchronous, the monitoring node of the lead vehicle performs UDP multicast in a local autonomous time synchronization mode, and the on-board node module of each rescue vehicle in the rescue convoy uses the calendar information of the monitoring node of the lead vehicle as the clock source, and uses the workshop 5G cellular network of the 5G-CPE module to perform low-precision time synchronization on the on-board node modules of all rescue vehicles in the rescue convoy based on the time synchronization priority of the on-board node modules;

[0026] When the high-precision, low-precision PTP time synchronization mode or local autonomous time synchronization mode is not received within a certain period of time, the on-board node module of each rescue vehicle adopts the local manual time synchronization mode, and performs low-precision time synchronization on the system time of the other on-board node modules of the lead vehicle and the on-board node modules of other rescue vehicles in the rescue fleet based on the manually set system time of the monitoring node of the lead vehicle.

[0027] Furthermore, the first computing module in each rescue vehicle selects a monitoring node based on the CPU main frequency and MAC address ID based on the Bully election algorithm, including:

[0028] Filter the vehicle-mounted node module with the highest CPU main frequency as a candidate monitoring node. If the number of candidate monitoring nodes is 1, the vehicle-mounted node module is the monitoring node;

[0029] Otherwise, an election is performed based on the MAC address ID, and the vehicle-mounted node module with the largest MAC address ID is elected as the monitoring node, and the other vehicle-mounted node modules are elected as non-monitoring nodes;

[0030] If the monitoring node stops issuing the election factor within a predetermined time period, a new monitoring node is selected.

[0031] Furthermore, the monitoring node establishes communication with the timekeeping and timing module, including:

[0032] The first step is that the monitoring node sends a first UDP heartbeat message to the fixed IP address and port number of the timekeeping timing module;

[0033] In the second step, after receiving the first UDP heartbeat message, the timekeeping timing module responds to the monitoring node by sending a second UDP heartbeat message and a UDP data message; if the timekeeping timing module does not receive the first UDP heartbeat message within a continuous preset time period, the module returns to the first step;

[0034] In the third step, the monitoring node parses the received second UDP heartbeat message to determine the working status of the timekeeping and timing module and whether the current calendar information is valid;

[0035] The UDP datagram includes a sending timestamp.

[0036] Furthermore, if the working status of the timekeeping and timing modules of all rescue vehicles in the rescue team are synchronized, and the current calendar information is valid, each rescue vehicle uses the clock source of its own timekeeping and timing module as a reference to perform high-precision PTP time synchronization on other on-board node modules of the vehicle;

[0037] If the working status of the timekeeping and timing modules of some vehicles is synchronized, and the current calendar information is valid, the vehicle whose working status of the timekeeping and timing modules is synchronized will use the clock source of its own timekeeping and timing modules as a reference to perform high-precision PTP time synchronization on other on-board node modules of the vehicle; at the same time, for the rescue vehicle whose working status of the timekeeping and timing modules is not synchronized, the system time of the monitoring node of the rescue vehicle with the largest vehicle ID whose working status of the timekeeping and timing modules is synchronized will be used as a reference to perform high-precision PTP time synchronization on all on-board node modules of the vehicle based on the 5G cellular network.

[0038] Furthermore, the system time of the vehicle node module is synchronized with high precision based on the high precision PTP time synchronization mode of delay-request measurement, as follows:

[0039] The timekeeping module serves as a PTP server, and the monitoring node serves as a PTP client;

[0040] The PTP server sends a Sync message to the PTP client and records the message sending time t1;

[0041] The PTP client receives the Sync synchronization message and records the message reception time t2;

[0042] The PTP server puts t1 in the Follow_Up delay message and sends it to the PTP client. After receiving the message, the PTP client parses the time t1;

[0043] The PTP client sends a Delay_Req delay request message to the PTP server, and synchronously records the time t3 when the Delay_Req delay request message is sent. The PTP server receives the message and records the time t4 when it is received;

[0044] The PTP server puts the t4 time in the Delay_Resp delayed response message and sends it to the PTP client. The PTP client receives the message and parses t4; the PTP client obtains the time values ​​t1, t2, t3 and t4;

[0045] The time offset value Offset and network link delay Delay between the PTP server and the client are calculated as follows:

[0046] t2-t1-Offset=Delay

[0047] t4-(t3-Offset)=Delay

[0048] Calculation yields:

[0049] Offset=[(t2-t1)+(t3-t4)] / 2

[0050] Delay=[(t2-t1)+(t4-t3)] / 2

[0051] Based on the time deviation value Offset, the PTP client subtracts the Offset value from the local system time value to obtain the synchronization time with the high-precision clock source of the PTP server, and synchronously updates the local system time of the monitoring node.

[0052] Furthermore, the low-precision PTP time synchronization mode performs low-precision time synchronization on the system time of all vehicle-mounted node modules in the rescue team as follows:

[0053] The vehicle election includes:

[0054] Find the rescue vehicle whose working status of the punctual timing module is punctual. If the number of vehicles in the punctual status is greater than 1, select the rescue vehicle with the smallest vehicle ID value in the punctual status in the rescue team as the reference vehicle;

[0055] Otherwise, find the rescue vehicle whose timing module is in the state of being synchronized. If the number of vehicles in the state of being synchronized is greater than 1, select the rescue vehicle with the smallest vehicle ID value in the state of being synchronized in the rescue team as the reference vehicle;

[0056] Otherwise, find the rescue vehicle whose timing module is in the RTC timing state. If the number of vehicles in the RTC timing state is greater than 1, select the rescue vehicle with the smallest vehicle ID value in the RTC timing state in the fleet as the reference vehicle.

[0057] Based on the clock source of the timekeeping module of the reference vehicle, time synchronization is performed on other on-board node modules in the reference vehicle;

[0058] At the same time, the workshop 5G cellular network of the 5G-CPE module is used to synchronize the onboard node modules of other vehicles in the fleet with low-precision time;

[0059] Based on the local autonomous time synchronization mode, the system time of all vehicle-mounted node modules in the rescue team is synchronized with low precision, including:

[0060] Each on-board node module in the lead vehicle is based on the system time and time synchronization priority information of the periodic UDP multicast of other on-board node modules in the node resource pool; the system time of the on-board node module with the highest time synchronization priority is selected, and the validity of the selected system time is judged based on the preset valid time threshold. If valid, the system time of the on-board node module is updated to the selected system time;

[0061] The system time of the monitoring node of the lead vehicle is used as the highest priority clock source, and the on-board node modules of other vehicles in the fleet are synchronized and updated to the system time of the monitoring node of the lead vehicle using the workshop 5G cellular network of 5G-CPE;

[0062] Based on the local manual time synchronization mode and the manually set system time of the monitoring node of the lead vehicle, low-precision time synchronization is performed on the system time of all vehicle-mounted node modules in the rescue fleet, including:

[0063] Use the time modification interface of the lead vehicle's operation command vehicle terminal to set the system time of the lead vehicle's monitoring node;

[0064] Determine the validity of the system time of the monitoring node of the set lead vehicle based on the preset effective time threshold;

[0065] If valid, the system time of other on-board node modules of the lead vehicle and the on-board node modules of other rescue vehicles in the rescue convoy will be synchronized to the system time of the monitoring node of the lead vehicle.

[0066] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0067] 1. The operating system time synchronization method in this invention is an independently controllable custom research and development based on the domestic openEuler operating system and domestic chips. This method not only improves the performance and reliability of the rescue team's on-board embedded information platform, but also ensures the platform's independent controllability and security, meeting the rescue team's needs for multi-vehicle and unmanned vehicle collaborative operations in complex environments.

[0068] 2. This invention uses a high-precision PTP time synchronization mode. Based on the high-precision clock source of the timekeeping timing module, it can achieve sub-microsecond high-precision time synchronization through precise timestamp exchange and deviation calculation. Compared with traditional methods that can only achieve millisecond or second-level accuracy, this greatly improves time synchronization accuracy, meets the higher requirements for time synchronization accuracy under the new networked architecture of the rescue team's electronic system, and provides reliable time guarantee for complex operations involving multiple vehicles in the rescue team.

[0069] 3. This invention adopts a multi-source time synchronization strategy, breaking through the limitations of a traditional single time source and integrating multiple time sources. It adopts a multi-source time synchronization strategy with four modes: high-precision PTP time synchronization mode, low-precision PTP time synchronization mode, local autonomous time synchronization mode, and local manual time synchronization mode. This multi-source time synchronization strategy enhances the adaptability and robustness of the rescue team system, ensuring that the system time synchronization of the rescue team's onboard node modules can be achieved in different environments and equipment states.

[0070] 4. The present invention is based on the Bully election algorithm, which comprehensively considers the CPU main frequency and MAC address to elect monitoring nodes. First, the node with the highest CPU main frequency is selected as the candidate monitoring node. If the number of candidate nodes is greater than 1, the node with the largest MAC address value is selected as the monitoring node based on the MAC address ID. This election mechanism can select monitoring nodes with better performance and stronger uniqueness, thereby improving the rationality and accuracy of monitoring node election. At the same time, when the monitoring node stops publishing the election factor within a predetermined time period, the monitoring node can be reselected in time to ensure the stable operation of the rescue vehicle in the event of a vehicle-mounted node failure or abnormality;

[0071] 5. The present invention uses 5G-CPE to connect the rescue team workshop to the 5G cellular network, realizing high-speed, low-latency, and highly reliable communication for the rescue team. The high bandwidth and low-latency characteristics of the 5G network support the rapid transmission and real-time response of large amounts of data, ensuring the real-time and reliability of the collaborative control of the rescue workshop; mobility management and anti-interference technology ensure the communication stability of the rescue vehicle under high-speed movement and complex electromagnetic environments. Through seamless integration with the on-board embedded information platform of the rescue vehicle, 5G-CPE supports multi-vehicle collaboration and time synchronization, improving the operating efficiency and safety of the rescue team. At the same time, the encrypted communication and identity authentication mechanism of the 5G network enhances security and ensures the confidentiality and integrity of data transmission;

[0072] 6. The present invention can flexibly adjust the time synchronization mode according to the working status of the timekeeping and timing module and the valid status of the current calendar information. When the working status of the timekeeping and timing module changes, the monitoring node can promptly judge and switch to the corresponding time synchronization mode, such as switching from high-precision PTP mode to low-precision PTP mode or local autonomous time synchronization mode. This flexible time synchronization mechanism enables the vehicle-mounted embedded information platform of the rescue team to quickly adapt to changes in the working status of the timekeeping and timing module, ensure the continuity and stability of time synchronization, avoid time synchronization interruptions caused by equipment failure or signal instability, and ensure the efficient coordination of the rescue team in various operational tasks and the accuracy of information transmission.

[0073] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of the present invention will be described in the following description, and some advantages will become apparent from the description or be learned through practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0075] Figure 1 Schematic diagram of a system time synchronization device for a rescue team based on the openEuler system in an embodiment of the present invention;

[0076] Figure 2 This is a flow chart of the monitoring node election algorithm in an embodiment of the present invention;

[0077] Figure 3 This is a flowchart of the time synchronization mode determination process in an embodiment of the present invention;

[0078] Figure 4 Schematic diagram of high-precision PTP time synchronization in an embodiment of the present invention;

[0079] Figure 5 Schematic diagram of a high-precision PTP time synchronization mechanism based on delay-request measurement in an embodiment of the present invention;

[0080] Figure 6 This is a schematic diagram of local autonomous time synchronization in an embodiment of the present invention;

[0081] Figure 7 Schematic diagram of local manual time synchronization in an embodiment of the present invention. DETAILED DESCRIPTION

[0082] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, and are not used to limit the scope of the present invention.

[0083] A specific embodiment of the present invention, as Figure 1 As shown, a system time synchronization device for a rescue vehicle fleet based on the openEuler system is disclosed. Each rescue vehicle includes a BeiDou module, a timekeeping timing module, an on-board node module, and a 5G-CPE module.

[0084] The Beidou module is used to transfer the Beidou astronomical time TOD obtained from the received Beidou satellite signal to the timekeeping timing module;

[0085] The timekeeping and timing module is used to receive the Beidou astronomical time;

[0086] The on-board node module includes multiple on-board terminals and multiple computing and processing modules in an on-board computer; the on-board terminals and computing and processing modules all use the domestic openEuler operating system and domestic chips; wherein, a monitoring node is selected from all online on-board node modules in each rescue vehicle, and the monitoring node synchronizes the system time of the on-board node modules of the rescue team based on the working status of the timekeeping and timing module of the vehicle and the validity of the calendar information, using high-precision PTP time synchronization, low-precision PTP time synchronization, local autonomous time synchronization or local manual time synchronization mode;

[0087] The 5G-CPE module is used to realize the networking of all vehicles in the rescue team, as well as the networking of each rescue vehicle with the command center module;

[0088] The command center module assigns a unique vehicle ID to each rescue vehicle in the rescue team and identifies the lead vehicle and the following vehicle.

[0089] In each rescue vehicle, the first, second, or third computing and processing module is selected to select a monitoring node from all online vehicle-mounted node modules. If the first, second, or third computing and processing module is offline or fails, the operation command vehicle-mounted terminal, the operation operation vehicle-mounted terminal, or the driver's vehicle-mounted terminal is selected in turn to select a monitoring node.

[0090] The elected monitoring node may be the vehicle-mounted node module itself that performs the election.

[0091] The onboard computer further comprises:

[0092] A power module, used to supply power to the onboard computer;

[0093] A network switching module is used to provide an Ethernet connection for each rescue vehicle and to connect with the 5G-CPE module.

[0094] Each vehicle-mounted node module, Beidou module and time-keeping timing module in each rescue vehicle in the rescue fleet are connected via Ethernet;

[0095] Each rescue vehicle, as well as each rescue vehicle and the command center module are connected to a 5G cellular network based on the 5G-CPE module.

[0096] Assign a unique vehicle ID to each special vehicle in the fleet and index it to determine the lead vehicle and the following vehicles. The lead vehicle has the smallest vehicle ID, and the following vehicles have increasing vehicle IDs.

[0097] The vehicle terminal module and the first, second and third computing and processing modules all use domestic chips; the vehicle terminal uses Rockchip RK3588 CPU processor; the computing and processing module uses Feiteng FD-2000 / 8-core CPU processor. For example, based on the needs of the rescue team, the vehicle computer can include multiple computing and processing modules. According to specific needs, more computing and processing modules can be virtualized using virtual technology. Figure 1 Three computing processing modules are taken as an example.

[0098] A rescue team consists of multiple rescue vehicles. The embedded information platform deployment structure diagram of each rescue vehicle is as follows: Figure 1 The first, second, and third computing and processing modules and the driver's vehicle-mounted terminal, the operation command vehicle-mounted terminal, and the operation operation vehicle-mounted terminal are collectively referred to as vehicle-mounted node modules.

[0099] The first, second and third computing and processing modules use the domestic openEuler operating system and the domestic Feiteng FD-2000 / 8-core CPU processor; the on-board terminals are mainly divided into three types of terminals: operation command on-board terminal, operation operation on-board terminal, and driver on-board terminal. The on-board terminals use the domestic openEuler operating system and the domestic Rockchip RK3588CPU processor.

[0100] Set the time synchronization priority of all onboard node modules of the vehicle, and multicast the IP address, CPU main frequency, time synchronization priority and MAC address ID of each onboard node module of the vehicle into the node resource pool through UDP;

[0101] Each rescue vehicle selects a monitoring node from each onboard node module based on the CPU main frequency and MAC address ID in the node resource pool. The monitoring node establishes communication with the timekeeping and timing module to determine the working status of the timekeeping and timing module and the validity status of the current calendar information.

[0102] The monitoring node of each rescue vehicle determines the time synchronization mode based on the working status of the timekeeping and timing module and the valid status of the current calendar information, and synchronizes the system time of each vehicle-mounted node module in the rescue fleet based on the time synchronization mode and the time synchronization priority.

[0103] The vehicle-mounted terminal device that performs monitoring node election sets the time synchronization priority of all vehicle-mounted node modules in the vehicle.

[0104] Define the time synchronization priority profile, deploy the priority profile to the vehicle node modules (each vehicle terminal and each computing and processing module), and complete the priority setting of each type of vehicle terminal and computing and processing module.

[0105] The time synchronization priorities of various types of vehicle-mounted terminals are divided according to specific actual usage requirements, as shown in Table 1. The larger the priority value, the higher the priority level. For example, the time synchronization priority of the vehicle-mounted terminal is defined as: operation command vehicle-mounted terminal > operation operation vehicle-mounted terminal > driver vehicle-mounted terminal. The time synchronization priority of the vehicle-mounted terminal is greater than the priority of the first, second and third calculation and processing modules.

[0106] Table 1 Description of vehicle-mounted node time synchronization priority

[0107] Vehicle-mounted nodes Time synchronization priority Operation command vehicle terminal 3 Operation vehicle terminal 2 Driver's vehicle terminal 1 First, second and third computing processing modules 0

[0108] Each vehicle-mounted node module multicasts its own IP address, CPU main frequency, time synchronization priority and MAC address ID into the node resource pool via UDP (User Datagram Protocol).

[0109] Based on the fixed IP addresses of each vehicle-mounted node module preset when the rescue team is networked, each vehicle-mounted node module periodically dials its own IP address, CPU main frequency, time synchronization priority, and MAC address ID group into the node resource pool. For example, the period is 100ms.

[0110] The node resource pool includes the IP address, CPU main frequency, time synchronization priority and MAC address ID of all on-board node modules of the current vehicle and the latest system time synchronization update time data.

[0111] The CPU main frequency and MAC address ID of each node provide election factors for subsequent monitoring node elections.

[0112] Each rescue vehicle elects each on-board node module to obtain a monitoring node based on the CPU main frequency and MAC address ID in the node resource pool.

[0113] like Figure 2 As shown, the monitoring node election of each rescue vehicle in the rescue vehicle fleet. The first computing module in each rescue vehicle selects the monitoring node based on the CPU main frequency and MAC address ID based on the Bully election algorithm, including:

[0114] Filter the vehicle-mounted node module with the highest CPU main frequency as a candidate monitoring node. If the number of candidate monitoring nodes is 1, the vehicle-mounted node module is the monitoring node;

[0115] Otherwise, an election is performed based on the MAC address ID, and the vehicle-mounted node module with the largest MAC address ID is elected as the monitoring node, and the other vehicle-mounted node modules are elected as non-monitoring nodes;

[0116] If the monitoring node stops issuing the election factor within a predetermined time period, a new monitoring node is selected.

[0117] Because the MAC address IDs of each onboard node module in an in-vehicle network environment are unique, assuming consistent CPU frequencies, the node with the largest MAC address ID can be elected as the monitoring node, while the remaining nodes are elected as non-monitoring nodes. Since the Feiteng FD-2000 / 8-core CPU processor has a higher CPU frequency than the Rockchip RK3588 CPU processor, the first, second, or third computing processing module is often elected as the monitoring node. This ensures the uniqueness of monitoring nodes and simplifies the election logic. When CPU frequencies are consistent, the node with the largest MAC address ID is selected as the monitoring node, providing a clear identification feature that facilitates identification and location by system administrators. During system management and maintenance, MAC address IDs can be used to quickly locate monitoring nodes for configuration, monitoring, and troubleshooting, improving management convenience and efficiency.

[0118] The monitoring node's operating status is determined based on the most recent system time synchronization update time in the node resource pool. If the monitoring node stops periodically publishing the election factor and the update exceeds a predetermined time period, a new monitoring node is elected. For example, the predetermined time period is 5 seconds.

[0119] The monitoring node frequently exchanges data with the timekeeping and timing module. In order to reduce the network bandwidth pressure of the rescue vehicle, the algorithm dynamically selects a monitoring node from the on-board node modules that need to be time synchronized, and conducts point-to-point network communication with the timekeeping and timing module. This method can effectively improve the network resource utilization of the rescue vehicle and can adapt to the on-board embedded environment with limited network resources.

[0120] Establish communication between the monitoring node and the timekeeping and timing module to determine the working status of the timekeeping and timing module and the validity status of the current calendar information.

[0121] The monitoring node establishes communication with the timekeeping and timing module, including:

[0122] The first step is that the monitoring node sends a first UDP heartbeat message to the fixed IP address and port number of the timekeeping timing module;

[0123] In the second step, after receiving the first UDP heartbeat message, the timekeeping timing module responds to the monitoring node by sending a second UDP heartbeat message and a UDP data message; if the timekeeping timing module does not receive the first UDP heartbeat message within a continuous preset time period, the module returns to the first step;

[0124] In the third step, the monitoring node parses the received second UDP heartbeat message to determine the working status of the timekeeping and timing module and whether the current calendar information is valid;

[0125] The UDP datagram includes a sending timestamp.

[0126] The monitoring node actively sends the first UDP heartbeat message to the fixed IP address and port number of the timekeeping module. For example, the sending period is 1 second, and the UDP heartbeat message format follows the IEEE802.3 Ethernet IP / UDP encapsulation format. For example, the UDP heartbeat message includes: IP message header, UDP message header, message ID, message payload length, and cycle count field, as shown in Table 2.

[0127] Table 2: First UDP heartbeat message data protocol

[0128]

[0129] The first UDP heartbeat message protocol has a total length of 40 bytes and includes:

[0130] (1) IP header, 20 bytes in length, following the IP encapsulation format of TCP / IP, RFC1122, and RFC1123 protocols, mainly including the source IP address (IP address of the monitoring node) and the destination IP address (IP address of the timekeeping module);

[0131] (2) UDP message header, 8 bytes in length, which complies with the UDP encapsulation format of RFC768 protocol, mainly including the source port number (monitoring node port number), destination port number (timekeeping module port number), length, checksum, etc.

[0132] (3) Message ID, 4 bytes in length. For example, the first UDP heartbeat message ID is 0x111222, used to identify the message type.

[0133] (4) Message payload length, 4 bytes, used to indicate the payload data length;

[0134] (5) Cycle count, 4 bytes in length, used to count the number of times the monitoring node sends the first UDP heartbeat message. The physical value range is [0, 4294967295], used to represent the number of heartbeats. When the maximum value of 4294967295 is reached, it loops back to 0.

[0135] After the punctuality timing module receives the first UDP heartbeat message sent by the monitoring node, it records the source IP address and source port number of the first UDP heartbeat message (the IP address and port number of the monitoring node); the punctuality timing module responds to the source IP address and source port number and sends a second UDP heartbeat message. For example, the period is 1 second, and the second UDP heartbeat message format follows the IEEE802.3 Ethernet IP / UDP encapsulation format. For example, the second UDP heartbeat message includes fields such as IP message header, UDP message header, message ID, message payload length, cycle count, and the specific format is shown in Table 3. The monitoring node receives the second UDP heartbeat message from the punctuality timing module and confirms that the punctuality timing module is online.

[0136] The timekeeping and timing module encapsulates its own working status data into a UDP datagram and sends the working status message data of the timekeeping and timing module to the source IP address and source port number. The working status message format of the timekeeping and timing module complies with the IEEE802.3 Ethernet IP / UDP encapsulation format. For example, the second UDP heartbeat message includes: an IP message header, a UDP message header, a message ID, a message payload length, the clock synchronization status of the timekeeping and timing module, and a current calendar information validity status field. The specific message format is shown in Table 3.

[0137] Table 3 Second UDP heartbeat message data protocol

[0138]

[0139]

[0140] The second UDP heartbeat message has a total length of 40 bytes and includes:

[0141] (1) IP header, 20 bytes in length, following the IP encapsulation format of TCP / IP, RFC1122, and RFC1123 protocols, including the source IP address (IP address of the timing module) and the destination IP address (IP address of the monitoring node);

[0142] (2) UDP message header, 8 bytes in length, following the UDP encapsulation format of RFC768 protocol, mainly including source port number (timekeeping module port number), destination port number (monitoring node port number), length, and checksum;

[0143] (3) Message ID, 4 bytes in length. The second UDP heartbeat message ID is 0x222333, used to identify the message type.

[0144] (4) Message payload length, 4 bytes, used to indicate the payload data length;

[0145] (5) Clock synchronization status of the timekeeping module, length 1 byte, physical value range: {0,1,2,3,4}, 0 means asynchronous, 1 means in synchronization, 2 means synchronized, 3 means on time, 4 means RTC (Real-Time Clock) timing;

[0146] 0: Asynchronous state, indicating that the timing module is not currently synchronized with the time source of the Beidou module;

[0147] 1: In the time synchronization state, it means that the timekeeping and timing module is synchronizing with the time source of the Beidou module, but the synchronization has not yet been completed;

[0148] 2: Synchronized state, indicating that the timing module has been successfully synchronized with the time source of the Beidou module, and the current time is the most accurate;

[0149] 3: Timekeeping state, which means that the timekeeping timing module relies on its own clock source (such as constant temperature crystal oscillator, rubidium atomic clock, etc.) to maintain time accuracy when the Beidou module's time source is lost;

[0150] 4: RTC timing status, indicating that the timekeeping timing module uses the RTC module to provide time information. It is usually used to provide basic time functions when there is no time source from the Beidou module.

[0151] (6) Current calendar information validity status, length 1 byte, physical value range: {0,1}, 0 means invalid, 1 means valid; reserved bits occupy 2 bytes;

[0152] The monitoring node parses the second UDP heartbeat message and determines the working status of the timekeeping and timing module. If the timekeeping and timing module does not receive the first UDP heartbeat message sent by the monitoring node for 10 consecutive seconds, it is determined that the connection communication is interrupted. At this time, the timekeeping and timing module terminates the sending of all UDP data messages and the second UDP heartbeat message, stops receiving all UDP data messages, and restarts the communication connection between the monitoring node and the timekeeping and timing module.

[0153] The monitoring node parses the UDP data of the timekeeping and timing module to obtain the validity data of the calendar information of the working status of the timekeeping and timing module.

[0154] like Figure 3 As shown, if the working status of the timekeeping and timing modules in all rescue vehicles in the rescue team are synchronized or the working status of the timekeeping and timing modules in some rescue vehicles is synchronized, and the current calendar information is valid, each rescue vehicle adopts the high-precision PTP time synchronization mode to perform high-precision time synchronization on each vehicle-mounted node module based on the timekeeping and timing module clock source;

[0155] If the working status of the timekeeping and timing module is synchronizing, timekeeping or RTC timing, and the current calendar information is valid, a vehicle is selected based on the workshop 5G cellular network of the 5G-CPE module to obtain a reference vehicle, and a low-precision PTP time synchronization mode is used to perform low-precision time synchronization on the system time of the on-board node modules in the rescue team based on the clock source of the timekeeping and timing module of the reference vehicle;

[0156] If the working states of the timekeeping and timing modules of all vehicles in the rescue convoy are asynchronous, the monitoring node of the lead vehicle performs UDP multicast in a local autonomous time synchronization mode, and the on-board node module of each rescue vehicle in the rescue convoy uses the calendar information of the monitoring node of the lead vehicle as the clock source, and uses the workshop 5G cellular network of the 5G-CPE module to perform low-precision time synchronization on the on-board node modules of all rescue vehicles in the rescue convoy based on the time synchronization priority of the on-board node modules;

[0157] When the high-precision, low-precision PTP time synchronization mode or local autonomous time synchronization mode is not received within a certain period of time, the on-board node module of each rescue vehicle adopts the local manual time synchronization mode, and performs low-precision time synchronization on the system time of the other on-board node modules of the lead vehicle and the on-board node modules of other rescue vehicles in the rescue fleet based on the manually set system time of the monitoring node of the lead vehicle.

[0158] For example, the priority definitions of the four modes of high-precision PTP time synchronization, low-precision PTP time synchronization, local autonomous time synchronization, and manual time synchronization are as shown in Table 4. The larger the priority value, the higher the priority level.

[0159] Table 4 Time synchronization mode priority description

[0160] Mode Name Priority High-precision PTP time synchronization mode 4 Low-precision PTP time synchronization mode 3 Manual time synchronization mode 2 Local autonomous time synchronization mode 1

[0161] Based on the different environmental conditions of the existing vehicles, a variety of time synchronization modes between rescue vehicles are provided based on the different time source information in the rescue vehicle. High-precision PTP time synchronization such as Figure 4 shown.

[0162] If the working status of the timekeeping and timing modules of all rescue vehicles in the rescue team are synchronized, and the current calendar information is valid, each rescue vehicle uses the clock source of its own timekeeping and timing module as a reference to perform high-precision PTP time synchronization on other on-board node modules of the vehicle;

[0163] If the working status of the timekeeping and timing modules of some vehicles is synchronized, and the current calendar information is valid, the vehicle whose working status of the timekeeping and timing modules is synchronized will use the clock source of its own timekeeping and timing modules as a reference to perform high-precision PTP time synchronization on other on-board node modules of the vehicle; at the same time, for the rescue vehicle whose working status of the timekeeping and timing modules is not synchronized, the system time of the monitoring node of the rescue vehicle with the largest vehicle ID whose working status of the timekeeping and timing modules is synchronized will be used as a reference to perform high-precision PTP time synchronization on all on-board node modules of the vehicle based on the 5G cellular network.

[0164] The high-precision PTP time synchronization mode based on delay-request measurement performs high-precision time synchronization on the system time of the vehicle node module as follows:

[0165] The timekeeping module serves as a PTP server, and the monitoring node serves as a PTP client;

[0166] The PTP server sends a Sync message to the PTP client and records the message sending time t1;

[0167] The PTP client receives the Sync synchronization message and records the message reception time t2;

[0168] The PTP server puts t1 in the Follow_Up delay message and sends it to the PTP client. After receiving the message, the PTP client parses the time t1;

[0169] The PTP client sends a Delay_Req delay request message to the PTP server, and synchronously records the time t3 when the Delay_Req delay request message is sent. The PTP server receives the message and records the time t4 when it is received;

[0170] The PTP server puts the t4 time in the Delay_Resp delayed response message and sends it to the PTP client. The PTP client receives the message and parses t4; the PTP client obtains the time values ​​t1, t2, t3 and t4;

[0171] The time offset value Offset and network link delay Delay between the PTP server and the client are calculated as follows:

[0172] t2-t1-Offset=Delay

[0173] t4-(t3-Offset)=Delay

[0174] Calculation yields:

[0175] Offset=[(t2-t1)+(t3-t4)] / 2

[0176] Delay=[(t2-t1)+(t4-t3)] / 2

[0177] Based on the time deviation value Offset, the PTP client subtracts the Offset value from the local system time value to obtain the synchronization time with the high-precision clock source of the PTP server, and synchronously updates the local system time of the monitoring node.

[0178] Based on the IEEE 1588V2 (PTP) protocol time synchronization method, high-precision PTP time synchronization of the on-board node modules is achieved. Based on the time synchronization mechanism of delay-request measurement, high-precision PTP time synchronization of the on-board node modules of each rescue vehicle is completed.

[0179] The timekeeping and timing module broadcasts synchronization messages through Ethernet; the on-board node module responds to the synchronization messages; the timekeeping and timing module sends delay response messages to each on-board node module, and each on-board node module calculates the network link delay and time deviation value, and performs high-precision calibration on the local time of each on-board node module.

[0180] The time synchronization mechanism based on delay-request measurement completes the time synchronization between the timekeeping timing module and the onboard node module of each rescue vehicle. The specific process is as follows: Figure 5 As shown:

[0181] a) The PTP server sends a Sync message to the PTP client. The timing module records the time t1 when the Sync message is sent. After the PTP client receives the Sync message, it records the time t2 when it is received.

[0182] b) The PTP server places the t1 time in the Follow_Up delay message and sends it to the PTP client. After receiving this message, the PTP client software parses the time t1;

[0183] c) The PTP client sends a Delay_Req delay request message to the PTP server, and simultaneously records the time t3 when the Delay_Req delay request message is sent. After the PTP server receives the message, it records the time t4 when it is received;

[0184] d) The PTP server places the t4 time in the Delay_Resp delay response message and sends it to the PTP client. The PTP client receives this message and parses t4. At this point, the PTP client has received the four time values ​​t1, t2, t3, and t4 required for high-precision synchronization calculations, and can then calculate two key parameters: the time offset value Offset and the network link delay Delay:

[0185] High-precision time synchronization based on the PTP protocol can achieve higher accuracy than traditional timing methods through CAN (Controller Area Network) and Ethernet vehicle buses. Its timing accuracy reaches sub-microsecond level, which can meet the needs of multi-vehicle collaboration that requires higher time synchronization accuracy and complex operations such as firefighting, counter-terrorism, and rescue that require coordinated control of unmanned vehicles.

[0186] If the working status of the timekeeping and timing module is synchronizing, keeping time or RTC timing, it enters the low-precision PTP time synchronization mode.

[0187] The low-precision PTP time synchronization mode performs low-precision time synchronization on the system time of all vehicle-mounted node modules in the rescue team as follows:

[0188] The vehicle election includes:

[0189] Find the rescue vehicle whose working status of the punctual timing module is punctual. If the number of vehicles in the punctual status is greater than 1, select the rescue vehicle with the smallest vehicle ID value in the punctual status in the rescue team as the reference vehicle;

[0190] Otherwise, find the rescue vehicle whose timing module is in the state of being synchronized. If the number of vehicles in the state of being synchronized is greater than 1, select the rescue vehicle with the smallest vehicle ID value in the state of being synchronized in the rescue team as the reference vehicle;

[0191] Otherwise, find the rescue vehicle whose timing module is in the RTC timing state. If the number of vehicles in the RTC timing state is greater than 1, select the rescue vehicle with the smallest vehicle ID value in the RTC timing state in the fleet as the reference vehicle.

[0192] Based on the clock source of the timekeeping module of the reference vehicle, time synchronization is performed on other on-board node modules in the reference vehicle;

[0193] At the same time, the workshop 5G cellular network of the 5G-CPE module is used to perform low-precision time synchronization on the on-board node modules of other vehicles in the fleet.

[0194] like Figure 6 As shown, if the working states of the timekeeping and timing modules of all vehicles in the fleet are asynchronous, the monitoring node of the lead vehicle performs UDP multicast in a local autonomous time synchronization mode.

[0195] Based on the local autonomous time synchronization mode, the system time of all vehicle-mounted node modules in the rescue team is synchronized with low precision, including:

[0196] Each on-board node module in the lead vehicle is based on the system time and time synchronization priority information of the periodic UDP multicast of other on-board node modules in the node resource pool; the system time of the on-board node module with the highest time synchronization priority is selected, and the validity of the selected system time is judged based on the preset valid time threshold. If valid, the system time of the on-board node module is updated to the selected system time;

[0197] The system time of the monitoring node of the lead vehicle is used as the highest priority clock source, and the workshop 5G cellular network of 5G-CPE is used to synchronize the on-board node modules of other vehicles in the fleet with the system time of the monitoring node of the lead vehicle.

[0198] The on-board node multicasts its system time and time synchronization priority information in a 100ms period, and judges the validity of the selected system time based on the preset valid time threshold information. When the selected system time information is earlier than the threshold information, it is judged to be invalid and the processing is terminated. Otherwise, it is judged to be valid time information and the subsequent steps are processed. For example, the valid time threshold is set to 00:00:00:00 on January 1, 2023.

[0199] When the timing module is not working properly, it cannot receive high-precision time synchronization information. In order to ensure the normal operation of the rescue mission, a local manual time synchronization mode is provided for the vehicle and workshop timing mechanism.

[0200] like Figure 7 As shown, based on the local manual time synchronization mode and the manually set system time of the monitoring node of the lead vehicle, the system time of all vehicle-mounted node modules in the rescue team is synchronized with low precision, including:

[0201] Use the time modification interface of the lead vehicle's operation command vehicle terminal to set the system time of the lead vehicle's monitoring node;

[0202] Determine the validity of the system time of the monitoring node of the set lead vehicle based on the preset effective time threshold;

[0203] If valid, the system time of other on-board node modules of the lead vehicle and the on-board node modules of other rescue vehicles in the rescue convoy will be synchronized to the system time of the monitoring node of the lead vehicle.

[0204] The local manual time synchronization mode of the vehicle-mounted node module receives the time information set by the user through the time modification interface of the operation command vehicle terminal, and judges the validity of the time based on the valid time threshold information. When the modified time information is earlier than the threshold information, it is judged to be invalid and the processing is terminated. Otherwise, it is judged to be valid time information.

[0205] When the timekeeping and timing module is not working properly, it cannot receive high-precision time synchronization information and the local time of each on-board terminal is inconsistent with the actual time. In order to ensure that the clock information of the rescue vehicle can be manually modified in time, a local manual time synchronization method is provided. That is, the user manually sets the system time of the monitoring node of the lead vehicle through the time modification interface of the operation command on-board terminal. Under the premise that the set system time is valid, the synchronization time update of other on-board terminals and computing and processing modules in the lead vehicle and the synchronization time update of on-board terminals and computing and processing modules of other vehicles are completed to achieve time consistency of each on-board node.

[0206] In summary, the system time synchronization device for a rescue team based on the openEuler system according to an embodiment of the present invention has the following beneficial effects:

[0207] 1. The operating system time synchronization method in this invention is an independently controllable custom research and development based on the domestic openEuler operating system and domestic chips. This method not only improves the performance and reliability of the rescue team's on-board embedded information platform, but also ensures the platform's independent controllability and security, meeting the rescue team's needs for multi-vehicle and unmanned vehicle collaborative operations in complex environments.

[0208] 2. This invention uses a high-precision PTP time synchronization mode. Based on the high-precision clock source of the timekeeping timing module, it can achieve sub-microsecond high-precision time synchronization through precise timestamp exchange and deviation calculation. Compared with traditional methods that can only achieve millisecond or second-level accuracy, this greatly improves time synchronization accuracy, meets the higher requirements for time synchronization accuracy under the new networked architecture of the rescue team's electronic system, and provides reliable time guarantee for complex operations involving multiple vehicles in the rescue team.

[0209] 3. This invention adopts a multi-source time synchronization strategy, breaking through the limitations of a traditional single time source and integrating multiple time sources. It adopts a multi-source time synchronization strategy with four modes: high-precision PTP time synchronization mode, low-precision PTP time synchronization mode, local autonomous time synchronization mode, and local manual time synchronization mode. This multi-source time synchronization strategy enhances the adaptability and robustness of the rescue team system, ensuring that the system time synchronization of the rescue team's onboard node modules can be achieved in different environments and equipment states.

[0210] 4. The present invention is based on the Bully election algorithm, which comprehensively considers the CPU main frequency and MAC address to elect monitoring nodes. First, the node with the highest CPU main frequency is selected as the candidate monitoring node. If the number of candidate nodes is greater than 1, the node with the largest MAC address value is selected as the monitoring node based on the MAC address ID. This election mechanism can select monitoring nodes with better performance and stronger uniqueness, thereby improving the rationality and accuracy of monitoring node election. At the same time, when the monitoring node stops publishing the election factor within a predetermined time period, the monitoring node can be reselected in time to ensure the stable operation of the rescue vehicle in the event of a vehicle-mounted node failure or abnormality;

[0211] 5. The present invention uses 5G-CPE to connect the rescue team workshop to the 5G cellular network, realizing high-speed, low-latency, and highly reliable communication for the rescue team. The high bandwidth and low-latency characteristics of the 5G network support the rapid transmission and real-time response of large amounts of data, ensuring the real-time and reliability of the collaborative control of the rescue workshop; mobility management and anti-interference technology ensure the communication stability of the rescue vehicle under high-speed movement and complex electromagnetic environments. Through seamless integration with the on-board embedded information platform of the rescue vehicle, 5G-CPE supports multi-vehicle collaboration and time synchronization, improving the operating efficiency and safety of the rescue team. At the same time, the encrypted communication and identity authentication mechanism of the 5G network enhances security and ensures the confidentiality and integrity of data transmission;

[0212] 6. The present invention can flexibly adjust the time synchronization mode according to the working status of the timekeeping and timing module and the valid status of the current calendar information. When the working status of the timekeeping and timing module changes, the monitoring node can promptly judge and switch to the corresponding time synchronization mode, such as switching from high-precision PTP mode to low-precision PTP mode or local autonomous time synchronization mode. This flexible time synchronization mechanism enables the vehicle-mounted embedded information platform of the rescue team to quickly adapt to changes in the working status of the timekeeping and timing module, ensure the continuity and stability of time synchronization, avoid time synchronization interruptions caused by equipment failure or signal instability, and ensure the efficient coordination of the rescue team in various operational tasks and the accuracy of information transmission.

[0213] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A system time synchronization device for a rescue team based on the openEuler system, characterized in that: Each rescue vehicle includes a BeiDou module, a timekeeping timing module, an on-board node module, and a 5G-CPE module; The Beidou module is used to transfer the Beidou astronomical time TOD obtained from the received Beidou satellite signal to the timekeeping timing module; The timekeeping and timing module is used to receive the Beidou astronomical time; The vehicle-mounted node module includes multiple vehicle-mounted terminals and multiple computing and processing modules in the vehicle-mounted computer; the vehicle-mounted terminals and computing and processing modules all use the domestic openEuler operating system and domestic chips; A monitoring node is selected from all online on-board node modules in each rescue vehicle. The monitoring node synchronizes the system time of the on-board node modules of the rescue team using high-precision PTP time synchronization, low-precision PTP time synchronization, local autonomous time synchronization, or local manual time synchronization mode based on the working status of the timekeeping and timing module of the vehicle and the validity of the calendar information; The 5G-CPE module is used to realize the networking of all vehicles in the rescue team, as well as the networking of each rescue vehicle with the command center module; The command center module assigns a unique vehicle ID to each rescue vehicle in the rescue convoy, and identifies the lead vehicle and the following vehicle; If the working status of the timekeeping and timing modules in all rescue vehicles in the rescue team are synchronized or the working status of the timekeeping and timing modules in some rescue vehicles is synchronized, and the current calendar information is valid, each rescue vehicle adopts the high-precision PTP time synchronization mode to perform high-precision time synchronization on each vehicle-mounted node module based on the timekeeping and timing module clock source; If the working status of the timekeeping and timing module is synchronizing, timekeeping or RTC timing, and the current calendar information is valid, a vehicle is selected based on the workshop 5G cellular network of the 5G-CPE module to obtain a reference vehicle, and a low-precision PTP time synchronization mode is used to perform low-precision time synchronization on the system time of the on-board node modules in the rescue team based on the clock source of the timekeeping and timing module of the reference vehicle; If the working states of the timekeeping and timing modules of all vehicles in the rescue convoy are asynchronous, the monitoring node of the lead vehicle performs UDP multicast in a local autonomous time synchronization mode, and the on-board node module of each rescue vehicle in the rescue convoy uses the calendar information of the monitoring node of the lead vehicle as the clock source, and uses the workshop 5G cellular network of the 5G-CPE module to perform low-precision time synchronization on the on-board node modules of all rescue vehicles in the rescue convoy based on the time synchronization priority of the on-board node modules; When the high-precision, low-precision PTP time synchronization mode or local autonomous time synchronization mode is not received within a certain period of time, the on-board node module of each rescue vehicle adopts the local manual time synchronization mode, and performs low-precision time synchronization on the system time of the other on-board node modules of the lead vehicle and the on-board node modules of other rescue vehicles in the rescue fleet based on the manually set system time of the monitoring node of the lead vehicle.

2. The device according to claim 1, characterized in that The onboard computer further comprises: A power module, used to supply power to the onboard computer; A network switching module is used to provide an Ethernet connection for each rescue vehicle and to connect with the 5G-CPE module.

3. The device according to any one of claims 1-2, characterized in that The on-board node modules, Beidou modules and time-keeping modules in each rescue vehicle in the rescue convoy are connected via Ethernet; Each rescue vehicle, as well as each rescue vehicle and the command center module, are connected to a 5G cellular network based on the 5G-CPE module.

4. The device according to claim 3, characterized in that Set the time synchronization priority of all onboard node modules of the vehicle, and multicast the IP address, CPU main frequency, time synchronization priority and MAC address ID of each onboard node module of the vehicle into the node resource pool through UDP; Each rescue vehicle selects a monitoring node from each onboard node module based on the CPU main frequency and MAC address ID in the node resource pool. The monitoring node establishes communication with the timekeeping and timing module to determine the working status of the timekeeping and timing module and the validity status of the current calendar information. The monitoring node of each rescue vehicle determines the time synchronization mode based on the working status of the timekeeping and timing module and the valid status of the current calendar information, and synchronizes the system time of each vehicle-mounted node module in the rescue fleet based on the time synchronization mode and the time synchronization priority.

5. The device according to claim 4, characterized in that The first computing module in each rescue vehicle selects a monitoring node based on the CPU main frequency and MAC address ID based on the Bully election algorithm, including: Filter the vehicle-mounted node module with the highest CPU main frequency as a candidate monitoring node. If the number of candidate monitoring nodes is 1, the vehicle-mounted node module is the monitoring node; Otherwise, an election is performed based on the MAC address ID, and the vehicle-mounted node module with the largest MAC address ID is elected as the monitoring node, and the other vehicle-mounted node modules are elected as non-monitoring nodes; If the monitoring node stops issuing the election factor within a predetermined time period, a new monitoring node is selected.

6. The device according to claim 4, characterized in that The monitoring node establishes communication with the timekeeping and timing module, including: The first step is that the monitoring node sends a first UDP heartbeat message to the fixed IP address and port number of the timekeeping timing module; In the second step, after receiving the first UDP heartbeat message, the timekeeping timing module responds to the monitoring node by sending a second UDP heartbeat message and a UDP data message; if the timekeeping timing module does not receive the first UDP heartbeat message within a continuous preset time period, the module returns to the first step; In the third step, the monitoring node parses the received second UDP heartbeat message to determine the working status of the timekeeping and timing module and whether the current calendar information is valid; The UDP datagram includes a sending timestamp.

7. The device according to claim 1, characterized in that If the working status of the timekeeping and timing modules of all rescue vehicles in the rescue team are synchronized, and the current calendar information is valid, each rescue vehicle uses the clock source of its own timekeeping and timing module as a reference to perform high-precision PTP time synchronization on other on-board node modules of the vehicle; If the working status of the timekeeping and timing modules of some vehicles is synchronized, and the current calendar information is valid, the vehicle whose working status of the timekeeping and timing modules is synchronized will use the clock source of its own timekeeping and timing modules as a reference to perform high-precision PTP time synchronization on other on-board node modules of the vehicle; at the same time, for the rescue vehicle whose working status of the timekeeping and timing modules is not synchronized, the system time of the monitoring node of the rescue vehicle with the largest vehicle ID whose working status of the timekeeping and timing modules is synchronized will be used as a reference to perform high-precision PTP time synchronization on all on-board node modules of the vehicle based on the 5G cellular network.

8. The device according to claim 1, characterized in that The high-precision PTP time synchronization mode based on delay-request measurement performs high-precision time synchronization on the system time of the vehicle node module as follows: The timekeeping module serves as a PTP server, and the monitoring node serves as a PTP client; The PTP server sends a Sync message to the PTP client and records the message sending time t1; The PTP client receives the Sync synchronization message and records the message reception time t2; The PTP server puts t1 in the Follow_Up delay message and sends it to the PTP client. After receiving the message, the PTP client parses the time t1; The PTP client sends a Delay_Req delay request message to the PTP server, and synchronously records the time t3 when the Delay_Req delay request message is sent. The PTP server receives the message and records the time t4 when it is received; The PTP server puts the t4 time in the Delay_Resp delayed response message and sends it to the PTP client. The PTP client receives the message and parses t4; the PTP client obtains the time values ​​t1, t2, t3 and t4; The time offset value Offset and network link delay Delay between the PTP server and the client are calculated as follows: t2-t1-Offset=Delay t4-(t3-Offset)=Delay Calculation yields: Offset=[(t2-t1)+(t3-t4)] / 2 Delay=[(t2-t1)+(t4-t3)] / 2 Based on the time deviation value Offset, the PTP client subtracts the Offset value from the local system time value to obtain the synchronization time with the high-precision clock source of the PTP server, and synchronously updates the local system time of the monitoring node.

9. The device according to claim 1, characterized in that The low-precision PTP time synchronization mode performs low-precision time synchronization on the system time of all vehicle-mounted node modules in the rescue team as follows: The vehicle election includes: Find the rescue vehicle whose working status of the punctual timing module is punctual. If the number of vehicles in the punctual status is greater than 1, select the rescue vehicle with the smallest vehicle ID value in the punctual status in the rescue team as the reference vehicle; Otherwise, find the rescue vehicle whose timing module is in the state of being synchronized. If the number of vehicles in the state of being synchronized is greater than 1, select the rescue vehicle with the smallest vehicle ID value in the state of being synchronized in the rescue team as the reference vehicle; Otherwise, find the rescue vehicle whose timing module is in the RTC timing state. If the number of vehicles in the RTC timing state is greater than 1, select the rescue vehicle with the smallest vehicle ID value in the RTC timing state in the fleet as the reference vehicle. Based on the clock source of the timekeeping module of the reference vehicle, time synchronization is performed on other on-board node modules in the reference vehicle; At the same time, the workshop 5G cellular network of the 5G-CPE module is used to synchronize the onboard node modules of other vehicles in the fleet with low-precision time; Based on the local autonomous time synchronization mode, the system time of all vehicle-mounted node modules in the rescue team is synchronized with low precision, including: Each on-board node module in the lead vehicle selects the system time and time synchronization priority information based on the periodic UDP multicast of other on-board node modules in the node resource pool; selects the system time of the on-board node module with the highest time synchronization priority, and determines the validity of the selected system time based on the preset valid time threshold. If valid, the system time of the on-board node module is updated to the selected system time; The system time of the monitoring node of the lead vehicle is used as the highest priority clock source, and the on-board node modules of other vehicles in the fleet are synchronized and updated to the system time of the monitoring node of the lead vehicle using the workshop 5G cellular network of 5G-CPE; Based on the local manual time synchronization mode and the manually set system time of the monitoring node of the lead vehicle, low-precision time synchronization is performed on the system time of all vehicle-mounted node modules in the rescue fleet, including: Use the time modification interface of the lead vehicle's operation command vehicle terminal to set the system time of the lead vehicle's monitoring node; Determine the validity of the system time of the monitoring node of the set lead vehicle based on the preset effective time threshold; If valid, the system time of other on-board node modules of the lead vehicle and the on-board node modules of other rescue vehicles in the rescue convoy will be synchronized to the system time of the monitoring node of the lead vehicle.

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