CN115276873A

CN115276873A - Time synchronization method, system, equipment and computer readable medium

Info

Publication number: CN115276873A
Application number: CN202210914082.5A
Authority: CN
Inventors: 方俊; 周东升
Original assignee: Hella Shanghai Electronics Co Ltd
Current assignee: Hella Shanghai Electronics Co Ltd
Priority date: 2022-08-01
Filing date: 2022-08-01
Publication date: 2022-11-01

Abstract

The application discloses a time synchronization method, which comprises the following steps: the Master node sends a Sync message and is received by a plurality of Slave nodes; the Master node sends a FollowUp message and is received by the plurality of Slave nodes; the Master node and the plurality of Slave nodes send Ready messages, the Ready messages are received by other nodes except the sending node, and the received Ready messages serve as input of time slot allocation for sending the Ready messages next time; and regulating radar sequencing and target output by calculating the time difference of the Ready messages of each corner radar. By utilizing the time synchronization method provided by the invention, the time calibration of all angle radars is completed among a plurality of angle radars based on the time reference of the Master angle radar, and the triggering of starting the angle radar measurement time sequence point based on an expected time point is realized. In the cycle period of sending the Sync message and the FollowUp message, each node corresponding to the angle radar additionally sends a Ready message, and the requirement of time synchronization with higher precision in a 77GHZ angle radar system is met.

Description

Time synchronization method, system, equipment and computer readable medium

Technical Field

The present application relates to the field of communications technologies, and in particular, to a time synchronization method, system, device, and computer readable medium.

Background

Time synchronization means that the time of each device is kept consistent. Problems may arise if the time of each device is not consistent. In the technical field of automatic driving, multi-sensor data acquisition such as a camera, a radar and a GPS provides very important information for automatic driving decision making. The environmental perception is used as a whole automatic driving visual nervous system, and the multi-sensor data needs to be fused and then calculated and identified, so that appropriate decisions are made on corresponding environments, and the corresponding environments are delivered to an execution mechanism to control vehicles. How to accurately fuse the information of a plurality of sensors has a vital role in accurately acquiring the information such as the spatial target position, the attitude, the motion direction and the like in real time by a system.

The multi-sensor time synchronization is that the time reference of each sensing unit under the system is adjusted to uniform reference time through some methods, then marking is carried out according to self-collected environment information and combining local time, and then the marking is sent to a main control, and the main control classifies according to a timestamp and generates the whole environment state at a certain time point when receiving messages sent by each sensor. Therefore, the reliability and accuracy of the data fusion information can be ensured only by ensuring the consistency of the local time of the multiple sensors.

The time synchronization is mostly applied to make the time references of all Slave nodes follow the time references of Master nodes, such time synchronization mostly synchronizes all nodes in a certain period, and each radar system operates based on its own frequency at the reference time, considering the difference of operating states and functions of radars with different angles, and the difference of automatic driving functions of front angle radars and rear angle radars exists in the normal case, such as forward-crossing alarm and rear-collision alarm, so for a single angle radar in the angle radar system, the time points of target detection (wave sending and wave receiving of the angle radar) and target output have uncertainty, and in addition, in the 77GHZ angle radar system, the speed of wave sending and wave receiving of the angle radar is fast, the data quantity of message transmission is large, and a faster period is needed for processing, so the angle radar system is in need of a more high-precision time synchronization.

Disclosure of Invention

The application provides a time synchronization method, which aims to solve the technical problem of how to obtain higher-precision time synchronization by a time angle radar system with uncertain time points of target detection and target output.

In order to solve the above technical problem, the present application provides a time synchronization method, including:

the Master node sends a Sync message and is received by a plurality of Slave nodes;

the Master node sends a FollowUp message and is received by the plurality of Slave nodes;

the Master node and the plurality of Slave nodes send Ready messages, the Ready messages are received by other nodes except the sending node, and the received Ready messages serve as input of time slot allocation for sending the Ready messages next time;

and regulating radar sequencing and target output by calculating the time difference of the Ready messages of each corner radar.

Further, a gateway SDE is added on the CAN bus to forward the time synchronization message of the CAN bus and increase the time compensation in the forwarding process.

Further, the cycle of the Sync message is 1s.

Further, the period of the Ready message is 50ms.

Further, the time synchronization Sync message includes the sending times and an initial mark of each synchronization, the FollowUp message includes a long-period global synchronization time parameter, the long-period global synchronization time parameter is the synchronization period of the FollowUp message plus compensation time for SDE forwarding, the Ready message includes a short-period synchronization time parameter, and the short-period synchronization time parameter is the long-period time plus offset time for requesting to send the Ready message.

Further, if the number of the angle radars is four, the dynamic allocation is performed in an offset manner, including:

first offset: a main angle radar S0 distributes a first time Slot Slot _1, a first angle radar S1 distributes a second time Slot Slot _2, a second angle radar S2 distributes a third time Slot Slot _3, and a third angle radar S3 distributes a main time Slot Slot _0;

second offset: the main angle radar S0 distributes a second time Slot Slot _2, the first angle radar S1 distributes a third time Slot Slot _3, the second angle radar S2 distributes a main time Slot Slot _0, and the third angle radar S3 distributes a first time Slot Slot _1;

third offset: the main angle radar S0 distributes a second time Slot Slot _3, the first angle radar S1 distributes a third time Slot Slot _0, the second angle radar S2 distributes a main time Slot Slot _1, and the third angle radar S3 distributes a first time Slot Slot _2;

and circularly performing the first time of offset, the second time of offset and the third time of offset in sequence until the time synchronization message is normally communicated among the angle radars.

In a second aspect, the present invention further provides a time synchronization system, including:

the processing unit is used for sending a Sync message by the Master node and receiving the Sync message by the plurality of Slave nodes; the Master node sends a FollowUp message and is received by the plurality of Slave nodes; the Master node and the plurality of Slave nodes send Ready messages, the Ready messages are received by other nodes except the sending node, and the received Ready messages serve as input of time slot allocation for sending the Ready messages next time;

and the calculation comparison unit is used for regulating and controlling radar sequencing and target output by calculating the time difference of the Ready message of each corner radar.

In a third aspect, the present invention provides an apparatus comprising: a processor and a memory; the memory for storing instructions or computer programs; the processor, which is used for executing the instructions or the computer program, executes the time synchronization method.

In a fourth aspect, the present invention provides a computer-readable storage medium comprising instructions or a computer program which, when run on a computer, cause the computer to perform the above time synchronization method.

The technical scheme at least comprises the following advantages: by utilizing the time synchronization method provided by the invention, the time calibration of all angle radars is completed among a plurality of angle radars based on the time reference of the Master angle radar, and the triggering of starting the angle radar measurement time sequence point based on the expected time point is realized. In the cycle period of sending the Sync message and the FollowUp message, each node corresponding to the angle radar additionally sends a Ready message, and the requirement of time synchronization with higher precision in a 77GHZ angle radar system is met.

Drawings

In order to more clearly illustrate the detailed description of the present application or the technical solutions in the prior art, the drawings needed to be used in the detailed description of the present application or the prior art description will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a schematic flow structure diagram of time synchronization provided in an embodiment of the present invention;

FIG. 2 is a schematic diagram of an angle radar mounted on a vehicle according to an embodiment of the present invention;

fig. 3 is a diagram illustrating an interference waveform analysis in an angle radar system according to an embodiment of the present invention;

FIG. 4 is a schematic diagram illustrating a period shift between radars according to an embodiment of the present invention;

fig. 5a is a schematic communication diagram of Sync and FollowUp messages according to an embodiment of the present invention;

fig. 5b is a schematic communication diagram of a Ready message according to an embodiment of the present invention;

FIG. 6 is a diagram illustrating a synchronization relationship between four corner radars according to an embodiment of the present invention;

fig. 7 is a timing diagram of synchronization with a gateway SDE according to an embodiment of the present invention.

Detailed Description

The technical solutions in the present application will be described clearly and completely with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all embodiments of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present application, it should be noted that, unless otherwise explicitly stated or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, a fixed connection, a detachable connection, or an integral connection; the connection can be mechanical connection or electrical connection; the two elements may be directly connected or indirectly connected through an intermediate medium, or may be connected through the inside of the two elements, or may be connected wirelessly or through a wire. The specific meaning of the above terms in this application will be understood to be a specific case for those of ordinary skill in the art.

In addition, the technical features mentioned in the different embodiments of the present application described below may be combined with each other as long as they do not conflict with each other.

Fig. 1 is a schematic view of a flow structure of time synchronization according to an embodiment of the present invention. Referring to fig. 1, the present invention provides a time synchronization method, including:

s11, a Master node sends a Sync message and is received by a plurality of Slave nodes;

s12, the Master node sends a FollowUp message and is received by the plurality of Slave nodes;

s13, the Master node and the plurality of Slave nodes send Ready messages, the Ready messages are received by other nodes except the sending node, and the received Ready messages serve as input of time slot allocation for sending the Ready messages next time;

and S14, regulating and controlling radar sequencing and target output by calculating the time difference of the Ready messages of each corner radar.

When a plurality of angle radars transmit message information to a plurality of CAN buses, a gateway SDE is required to be added for forwarding Sync messages, followUp messages and Ready messages of the CAN buses. One corner radar is set as a Master node, the other corner radars are set as Slave nodes, and long-period time synchronization is realized by sending a Sync message and a Follow message through the Master node. Meanwhile, each angle radar sends respective Ready time messages and receives the Ready messages of other angle radars, and short-period high-precision Ready time synchronization is achieved. In the embodiment of the invention, the cycle of the Sync message is 1s, and the cycle of the Ready message is 50ms.

The Sync message comprises sending times and an initial mark of each synchronization, the FollowUp message comprises a long-period global synchronization time parameter, the Ready message comprises a short-period synchronization time parameter, and the short-period synchronization time parameter is the long-period global synchronization time parameter plus offset time for requesting to send the Ready message.

When a gateway SDE is added on the CAN bus, the long-period global synchronization time parameter also comprises compensation time for forwarding the gateway SDE.

In the embodiment of the invention, the Master node is a main corner radar, and the Slave node is other corner radars except the main corner radar.

When the Sync message can not be normally communicated among the angle radars, the angle radars redistribute the time operation and dynamically distribute the time operation in an offset mode.

If the number of the angle radars is four, the angle radars are dynamically allocated in an offset mode, and the method comprises the following steps:

first-time offset: a main angle radar S0 distributes a first time Slot Slot _1, a first angle radar S1 distributes a second time Slot Slot _2, a second angle radar S2 distributes a third time Slot Slot _3, and a third angle radar S3 distributes a main time Slot Slot _0;

third offset: the main angle radar S0 distributes a third time Slot Slot _3, the first angle radar S1 distributes a main time Slot Slot _0, the second angle radar S2 distributes a first time Slot Slot _1, and the third angle radar S3 distributes a second time Slot Slot _2;

and circularly performing the first deviation, the second deviation and the third deviation in sequence until the Sync message is normally communicated among the angle radars.

If the number of the angle radars is six, the angle radars are dynamically allocated in an offset mode, and the method comprises the following steps:

first-time offset: a main angle radar S0 distributes a first time Slot Slot _1, a first angle radar S1 distributes a second time Slot Slot _2, a second angle radar S2 distributes a third time Slot Slot _3, a third angle radar S3 distributes a fourth time Slot main time Slot Slot _4, a fourth angle radar S4 distributes a fifth time Slot Slot _5, and a fifth angle radar S5 distributes a main time Slot Slot _0;

second offset: a main angle radar S0 distributes a second time Slot Slot _2, a first angle radar S1 distributes a third time Slot Slot _3, a second angle radar S2 distributes a fourth time Slot Slot _4, a third angle radar S3 distributes a fifth time Slot Slot _5, a fourth angle radar S4 distributes a main time Slot Slot _0, and the fifth angle radar S5 distributes a first time Slot Slot _1;

third offset: the master corner radar S0 is assigned the third time Slot _3, the first corner radar S1 is assigned the fourth time Slot _4, the second corner radar S2 is assigned the fifth time Slot _5, a third angle radar S3 is distributed with a main time Slot _0, a fourth angle radar S4 is distributed with a first time Slot _1, and a fifth angle radar S5 is distributed with a second time Slot _2;

fourth offset: a master corner radar S0 is distributed with a fourth time Slot _4, a first corner radar S1 is distributed with a fifth time Slot _5, a second corner radar S2 is distributed with the master time Slot _0, a third corner radar S3 is distributed with the first time Slot _1, a fourth corner radar S4 is distributed with the second time Slot _2, and a fifth corner radar S5 is distributed with the third time Slot _3;

fifth offset: a main angle radar S0 distributes a fifth time Slot Slot _5, a first angle radar S1 distributes a main time Slot Slot _0, a second angle radar S2 distributes a first time Slot Slot _1, a third angle radar S3 distributes a second time Slot Slot _2, a fourth angle radar S4 distributes a third time Slot Slot _3, and a fifth angle radar S5 distributes a fourth time Slot Slot _4;

and circularly performing the first offset, the second offset, the third offset, the fourth offset and the fifth offset in sequence until the Sync message is normally communicated among the angle radars.

If the number of the angle radars is eight, the allocation is also performed according to the above-mentioned offset dynamic allocation, which is not described herein again.

An embodiment of the present invention further provides a time synchronization system, including:

the processing unit is used for sending a Sync message by the Master node and receiving the Sync message by the plurality of Slave nodes; the Master node sends a FollowUp message and is received by the plurality of Slave nodes; the Master node and the plurality of Slave nodes send Ready messages, and the Ready messages contain sending time information;

the judging unit is used for confirming that the synchronization is successful when the Ready message is received by other nodes except the sending node and the sending times information in the Ready message received by the other nodes is consistent; the Sync message period is greater than the Ready message period;

and when the Ready message is successfully received by other nodes except the sending node and the sending time information in the Ready message received by the other nodes is inconsistent, resetting the sending times stored in the message by the nodes inconsistent with the sending time information of the other nodes.

In the 77GHZ angle radar system, the wave sending and receiving speed of the angle radar is fast, the data volume of message transmission is large, and a faster period is needed for processing, in the first embodiment of the invention, the vehicle system is provided with the four angle radars, and each node corresponding to the angle radar additionally sends a Ready message in a cycle period of sending a Sync message and a FollowUp message so as to meet the requirement of higher-precision time synchronization in the 77GHZ angle radar system.

In the first embodiment of the present invention, the Sync message includes the sending times and the start flag of synchronization every 1 second, the FollowUp includes a long-period global synchronization time parameter, the long-period global synchronization time parameter is the time of accumulating 1 second and the compensation time, the Ready _ Sx includes a short-period synchronization time parameter, and the short-period synchronization time parameter is the offset time of requesting to send the Ready _ Sx on the basis of the long-period time.

Fig. 2 is a schematic diagram of an angle radar installed on a vehicle according to an embodiment of the present invention. Referring to fig. 2, in the construction of the entire vehicle corner radar system, the corner radars are respectively installed at the left rear, right rear, left front and right front positions of the vehicle, S0 (left rear) is used as a Master node to send Sync, followUp, ready _ S0 messages, S1 (right rear), S2 (left front), and S3 (right front) are respectively sent Ready _ S1, ready _ S2, and Ready _ S3 messages, and the messages are all transmitted through the CAN bus.

For some special conditions, such as larger bus load, the front and rear radars are not suitable for the same CAN bus, and at this time, a gateway SDE is required to be added for forwarding Sync, followUp and Ready messages of the front and rear radar CAN buses. The CAN bus configures two paths of CAN for the gateway SDE to be used for angle radar interactive use, one path of CAN is used for the head communication of S0 and S1, the other path of CAN is used for the tail communication of S2 and S3, and the SDE interacts time synchronization messages on the head and the tail. S0 sends a long-period Sync/FollowUp message to a vehicle head end, after the SDE vehicle head end receives the Sync/FollowUp message, the message is forwarded to a vehicle tail end, and S2 and S3 successfully receive the long-period time information from S0. Similarly, S2 sends Ready _ S2 and S3 sends Ready _ S3 to the tail end, the tail end of the SDE receives the Ready _ S2 and the Ready _ S3 and then forwards the received Ready _ S2 and Ready _ S3 to the head end, and S0 and S1 successfully receive the high-precision short-cycle time parameter information from the S2 and the S3.

In addition, each message is added with Cyclic Redundancy Check (CRC) and Count (Cnt) signals to realize the end-to-end E2E function.

For high precision Ready time synchronization, immunity can be addressed by changing the time schedule by time offset. Fig. 3 is an analysis diagram of interference waveforms in the angle radar system according to an embodiment of the present invention. Referring to fig. 3, a normal interference-free scene is in a period n-1, interference with similar frequencies occurs in a period n, a bold waveform line is used for representing interference waves in fig. 3, and n +1, n +2, n +3 \ 823030is carried out after the interference waves are represented by the bold waveform line, wherein one is hardware modulation to change the wave-sending frequency, namely frequency increase or frequency reduction to avoid the interference waves with the similar frequencies, and the other is software modulation to adjust the wave-sending period, namely increase or decrease the wave-sending period to avoid the interference waves with the similar time offset points. After adjustment, the angle radar avoids interference waves occurring in the n period, in a complex practical application scene, such as a closed garage and a congested intersection, a complex reflection situation and a large amount of radar interference from other vehicles can occur in the scene, the interference waves cannot be avoided through repeated adjustment, at the moment, the radar can report an interference DTC (Diagnostic Trouble Code), and the interference resistance is increased for time offset and hardware frequency conversion which are performed by using time synchronization information rather than completely blocking the interference.

Fig. 4 is a schematic diagram illustrating a period shift between radars according to an embodiment of the present invention. Referring to fig. 4, the period of the ready message is 50ms, the period offset is the scheduling offset of each corner radar, and the scheduling offset is 0-50 ms, in the embodiment of the present invention, four radars are provided, the period offset between each radar is 12.5ms, so as to ensure that each corner radar can allocate an individual time slot thereof, the time slot is used for sending and receiving waves of each of the four corner radars, and the radar wave of the front radar is also received by the rear radar on the same side after being reflected by an obstacle, so that in a system built by the four corner radars, the interference of other radars in the system itself needs to be avoided.

Fig. 5a is a schematic communication diagram of Sync and FollowUp messages according to an embodiment of the present invention; fig. 5b is a schematic communication diagram of the Ready message according to the embodiment of the present invention. Referring to fig. 5a and 5b, for Sync/Follow long cycle time synchronization, S0 is generally set as a Master node, and the other three nodes are Slave nodes; for short-period high-precision Ready time synchronization, each angle radar sends the Ready _ Sx time message of the angle radar and receives the Ready _ Sx messages of other angle radars, and radar sequencing and target output are regulated and controlled by calculating and comparing the Ready _ Sx time difference of each angle radar. In fig. 5a and 5b, a gateway SDE is added, if there is no gateway SDE, a front and a back CAN buses are provided, and if there is an SDE, time compensation in the forwarding process needs to be added for forwarding the packet by the SDE.

In the embodiment of the present invention, the Sync message is composed of a 2-byte TimeSyncNumber signal, a 2-byte CRC signal, and a 1-byte CNT signal. The FollowUp message is of the multiplex type, multi _0 containing a 2-byte syncmsdcounter signal, a 4-byte lowprecision timestamp signal, multi _1 containing a 4-byte highrecertionsTimestamp signal, multi _2 containing a 4-byte correctionsF signal, and Multi _3 containing a 2-byte CRC signal and a 1-byte CNT signal. The Ready _ Sx message is also of a multiplex type, the Multi _0 includes a 4-byte EarliestStartTime signal and a 1-byte Radar _ Slot signal, and the Multi _1 includes a 4-byte CurrentCycleCount, a 2-byte CRC signal, and a 1-byte CNT signal. The length of each frame of the message is 8 bytes. The TimeSyncNumber represents the sending times of Sync messages, syncMgCounter represents the sending times of FollowUp messages, the signal value is the same as the TimeSyncNumber value, lowPrecisionTimeStamp represents a current second precision timestamp (Master Radar timestamp) when the FollowUp messages are sent, highReconsistionTimeStamp represents a current nanosecond precision timestamp (Master Radar timestamp) when the FollowUp messages are sent, correctnAild represents compensation time, when SDE exists, the information is filled by SDE, the SDE successfully receives the FollowUp to the SDE and successfully forwards the FollowUp to another RLCAN line, eiestTimeTimeStattTime represents a timestamp of the current Radar when Ready _ Sx is sent, curentCyclcount represents the sending times of Ready _ Sx messages, when synchronization is successful, the signal value of Ready _ Srad _ Sx messages is the same, the current Radar timestamp represents the sending times of the CryptorC _ CmCountCyc, and the CFCNT 2 count represents the encryption time for calculating the number of sending of the CryptorC messages, and the CFC Slot number of the CFC 2.

For the relation between messages, after CAN initialization is completed under an unlimited condition, a Sync message is sent on a Master node S0 in a period of 1 second, followUp is used as a trigger message, and when the Sync message is successfully sent, namely after an ACK response of successful bus sending is received, the Master node is triggered to send the FollowUp message. And after successfully receiving the Sync/FollowUp message, the Slave node sends a Ready _ Sx message in a 50-millisecond period. Under the condition of adding the gateway, the time parameter in the FollowUp message CAN increase the time for forwarding compensation, namely the time for successfully receiving the message and forwarding the message to another CAN line by the gateway, and because the time parameter in the Ready _ Sx is used as a time slot for calculating the wave receiving and sending and the target output, the time parameter in the Ready _ Sx does not need to increase the compensation time.

In the angle radar system according to the embodiment of the present invention, the task of processing the time synchronization information is defined as 10 milliseconds, the number of time slots matches the number of radars, and each angle radar is assigned with one time Slot to ensure that the radars are not interfered with each other, so that four angle radar time slots Slot _ x are defined, and the time slots are used for receiving and transmitting waves and outputting a target. In each time synchronization of Ready _ Sx, each angle radar successfully receives the Ready _ Sx messages of other three angle radars, namely, each angle radar is considered to be successfully synchronized and is used as the input of the next time slot allocation.

Under the normal working condition, the Sync message is normally communicated among the angle radars, and the angle radars normally carry out antenna wave sending and receiving and target output after algorithm according to the distributed time slots. Under abnormal conditions, such as communication abnormality (message is not normally sent and received), time synchronization abnormality, failure to acquire correct time parameters, failure of time slot allocation, during which the radar detection function is turned off and synchronization is waited for success, or interference from external radar waves (other vehicles equipped with radars of the same angle) occurs, the angle radars redistribute time operation and dynamically allocate in an offset manner. S0- > Slot _0, S1- > Slot _1, S2- > Slot _2, S3- > Slot _3 in the normal case, are dynamically allocated in an offset manner: adjusting for the first time: s0- > Slot _1, S1- > Slot _2, S2- > Slot _3, S3- > Slot _0, the second adjustment: s0- > Slot _2, S1- > Slot _3, S2- > Slot _0, S3- > Slot _1, and the third adjustment: and circularly adjusting the S0- > Slot _3, S1- > Slot _0, S2- > Slot _1 and S3- > Slot _2 in such a way until the time synchronization message can be normally communicated among the corner radars.

E2E encryption, the length of the applied message is 8 bytes, the CRC bits are filled with the value calculated by CRC8 for the message information and the self-defined DataID (2 bytes), and for Cnt, one frame is successfully sent for each time, and the summation is 1.

Firstly, time synchronization Sync message CAN bus is required to be successfully sent, and then FollowUp message (containing long period time parameter) is triggered to be sent, sync/FollowUp only needs to be sent by radar configured as Master. And when the Sync/FollowUp is correctly received by the Slave node, sending a short-period high-precision Ready message, wherein the Sync/FollowUp is a period of 1 second, and the Ready _ Sx is a period of 50mS.

Fig. 6 is a diagram of a synchronization relationship between four corner radars according to an embodiment of the present invention. Referring to fig. 6, under the situation of SDE without a gateway, four corner radar nodes are accessed to a CAN bus, when a Master node S0 is successfully configured in a corner radar system, a Sync message is sent to the bus by the Master node, an arrow points to represent that the message is sent to S1, S2 and S3 from S0, wherein, for the time point when the Slave node successfully receives, no front-back relation exists, after the Master node S0 successfully sends the Sync message, delta t is obtained_SFTriggering and sending the FollowUp message to the bus within 5 milliseconds, and in a similar way, the arrow points to the message which represents that the message is sent from S0 to the Slave nodes S1, S2 and S3, and the Sync and FollowUp message have the period of T_SEqual to 1 second, i.e. the interval between Sync n and Sync n +1 is 1 second. S0 successfully sends Sync and FollowUp messages, S1, S2 and S3 successfully receive the Sync and FollowUp messages, then the four corner radars S0, S1, S2 and S3 trigger to send Ready messages to the bus, the arrow of Ready _ Sx shown in FIG. 6 represents that each corner radar sends own Ready messages to other three corner radars and also represents that each corner radar needs to receive the Ready messages of other three corner radars, high-precision short-period synchronization needs to be input by combining time parameters of the four Ready messages, and the sending time sequence of the Ready messages in FIG. 6 is S0->S1->S2->And S3, the sequence is not fixed, and the requirements of sequence, sequence and interval are not met. The period of the Ready message is 50 milliseconds, namely, the high-precision time synchronization of the Ready message is completed once within 50mS. The timing specifically included in fig. 6 is: s0, sending a Sync message, successfully sending the Sync message and receiving the Sync message by other nodes; s0 sends FollowUp message after 5 milliseconds, and the message is successfully sent and sent by other nodesReceiving a point; s0, S1, S2 and S3 all send Ready messages, and the Ready messages are successfully sent and received by other nodes; s0, sending a Sync message, wherein the interval between the sending of the Sync message and the successful sending of the Sync message last time is 1 second; s0 sends a FollowUp message after 5 milliseconds; and S0, S1, S2 and S3 send the Ready message at an interval of 50 milliseconds with the last successful sending of the Ready message.

Fig. 7 is a timing diagram of synchronization with a gateway SDE according to an embodiment of the present invention. In fig. 7, a gateway SDE is added, and if there is no SDE, there is one CAN BUS in front and at the back, referring to fig. 7, BUS1 represents a rear angle radar BUS, i.e., the CAN buses of S0 and S1, and BUS2 represents a front angle radar BUS, i.e., the CAN buses of S2 and S3. The gateway SDE functions to forward Sync, followUp, ready _ S0 and Ready _ S1 on BUS1 onto BUS2 and Ready _ S3 on BUS2 onto BUS 1. Wherein the FollowUp transmission time Deltat_FAnd Ready _ Sx message transmission time Δ t_RThe forwarding time does not exceed 3 milliseconds at maximum. Specifically, S0 sends a Sync message, and the Sync message is successfully sent to BUS1 and received by S1 and SDE; the SDE forwards the Sync message, successfully forwards the Sync message to the BUS2 and receives the Sync message by the S2 and the S3; sending a FollowUp message 5 milliseconds later relative to the Sync message, successfully sending the FollowUp message to BUS1 and receiving the FollowUp message by S1 and SDE; SDE transmits a FollowUp message and fills a CorrectionField signal, and the message is successfully transmitted to BUS2 and received by S2 and S3; s0, S1 sends Ready message, and successfully sends the Ready message to BUS1 to be received by opposite side and SDE; the SDE forwards the Ready message of BUS1, successfully forwards the Ready message to BUS2 and receives the Ready message by S2 and S3; s2, S3 sends Ready message, and the Ready message is successfully sent to BUS2 to be received by opposite side and SDE; the SDE forwards the Ready message of the BUS2, successfully forwards the Ready message to the BUS1 and receives the Ready message by the S0 and the S1; the same steps are repeated after a period of 1 second compared to the last Sync and FollowUp messages.

When the gateway SDE forwards the message, all other signals except a CorrectionField signal are not changed and converted, the CorrectionField signal is contained in a FollowUp message and is sent by S0, S0 sends the CorrectionField to BUS1, the default value is 0, when the gateway SDE does not exist, the signal value is always 0, the gateway SDE records the current time T1 when successfully receiving FollowUp Multi _0 on BUS1, records the current time T2 when successfully sending FollowUp Multi _0 to BUS2, and the value of the CorrectionField is T2-T1, which is the time consumed by the gateway SDE for forwarding the message.

Wherein, T_SThe message period is 1 second, delta t, for Sync/FollowUp message period in the first embodiment of the present invention_SFThe interval time between the Sync message and the FollowUp message is delta t after the time parameter indicates that the Sync message is successfully sent_SFThe inner FollowUp message is also successfully sent, which is 5 milliseconds in the first embodiment of the present invention. Δ t_SRThe interval time between the Sync message and the Ready _ Sx message is shown; Δ t_RRThe interval time of the Ready _ Sx message and the Ready _ Sy message is shown; Δ t_SFor the transmission time of the Sync message, the message needs to be successfully sent to the CAN bus within 3 milliseconds; Δ t_FFor the transmission time of FollowUp, the transmission time needs to be successfully sent to the CAN bus within 3 milliseconds; Δ t_RThe message is transmitted to the CAN bus within 3 milliseconds for the Ready _ Sx message transmission time; t is a unit of_RA typical value is 50 milliseconds for the Ready _ Sx message period.

In addition, the invention also provides computer equipment. The computer device comprises a memory and a processor, wherein the memory can be used for storing a computer program, and the processor can make the computer device execute the time synchronization method or the functions of each module in the time synchronization system by operating the computer program.

The present invention provides a computer-readable storage medium comprising instructions or a computer program which, when run on a computer, cause the computer to perform the above time synchronization method.

The memory may include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for at least one function (such as a sound playing function, an image playing function, etc.), and the like. The storage data area may store data (such as audio data, a phonebook, etc.) created according to the use of the mobile terminal, and the like. Further, the memory may include high speed random access memory, and may also include non-volatile memory, such as at least one magnetic disk storage device, flash memory device, or other volatile solid state storage device.

The present embodiment also provides a computer storage medium for storing a computer program used in the above-described computer apparatus.

In the embodiments provided in the present application, it should be understood that the disclosed apparatus and method can be implemented in other ways. The apparatus embodiments described above are merely illustrative, and for example, the flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods and computer program products according to various embodiments of the present application. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

In addition, each functional module in the embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.

The functions, if implemented in the form of software functional modules and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application or portions thereof that substantially contribute to the prior art may be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the methods according to the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of this invention are intended to be covered by the scope of the invention as expressed herein.

Claims

1. A method of time synchronization, comprising:

the Master node and the plurality of Slave nodes send Ready messages, and the Ready messages contain sending time information;

when the Ready message is received by other nodes except the sending node, and the sending times information in the Ready message received by the other nodes is consistent, the synchronization is confirmed to be successful;

when the Ready message is successfully received by other nodes except the sending node and the sending time information in the Ready message received by the other nodes is inconsistent, resetting the sending times of the nodes which are inconsistent with the sending time information of the other nodes and stored in the message;

the Sync message period is greater than the Ready message period.

2. The time synchronization method according to claim 1, wherein when the Ready message fails to be received by a node other than the transmitting node, a synchronization failure is transmitted to the DTC controller.

3. The time synchronization method according to claim 1, wherein the Sync message, the FollowUp message, and the Ready message are sent to a CAN bus, and if the number of CAN buses is greater than 1, a gateway SDE is added to the CAN bus, and the gateway SDE forwards the Sync message, the FollowUp message, and the Ready message on the CAN bus and increases time compensation in the forwarding process.

4. The time synchronization method according to claim 1, wherein the Sync message has a period of 1s.

5. The method according to claim 1, wherein the period of the Ready message is 50ms.

6. The method according to claim 1, wherein the Sync message includes a sending time and a start flag of each synchronization, the FollowUp message includes a long-period global synchronization time parameter, and the Ready message includes a short-period synchronization time parameter, and the short-period synchronization time parameter is the long-period global synchronization time parameter plus an offset time for requesting to send the Ready message.

7. The time synchronization method according to claim 6, wherein the Sync message, the FollowUp message, and the Ready message are sent to a CAN bus, if the number of CAN buses is greater than 1, a gateway SDE is added to the CAN bus, and the long-period global synchronization time parameter further includes a backoff time for forwarding the gateway SDE.

8. The method of claim 1, wherein if the number of the angle radars is four, the dynamic allocation is performed in an offset manner, comprising:

9. A time synchronization system, comprising:

the judging unit is used for confirming that the synchronization is successful when the Ready message is received by other nodes except the sending node and the sending time information in the Ready message received by the other nodes is consistent; the Sync message period is greater than the Ready message period;

10. An apparatus, comprising: a processor and a memory;

the memory for storing instructions or computer programs;

the processor, for executing the instructions or the computer program, performs the method of any one of claims 1-8.

11. A computer-readable storage medium, comprising instructions or a computer program which, when run on a computer, cause the computer to perform the method of any one of claims 1 to 8.