An unmanned container truck automatic driving system time synchronization system and method

Abstract

An unmanned container truck automatic driving system time synchronization system, comprising: an automatic driving domain controller, a camera, an inertial navigation system and a laser radar, wherein: the camera is connected with the automatic driving domain controller through a MIPI interface; the inertial navigation system is connected with the automatic driving domain controller through an RS232 serial port line; the laser radar is connected with the automatic driving domain controller through an RS232 serial port line; PPS is distributed to the main SOC and the auxiliary SOC through the internal CPLD distribution of the controller, GPRMC signals are sent to multiple laser radars through multiple RS232 chip distributions, and GPRMC is sent to the main SOC and the auxiliary SOC through UDP, so that the time synchronization of the automatic driving domain controller and the multiple laser radars is solved, through double clock source setting, in the case of GPS time service exception, the internal clock source is adopted and is synchronized through NTP service, in the case of normal GPS time service, GPS time service is adopted, and the problem of system time exception in the case of GPS exception is solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of automatic driving, and particularly relates to a time synchronization method and system of an automatic driving system of an unmanned container truck. BACKGROUND

[0002] The automatic driving system of the unmanned container truck has high requirements on the time accuracy of the automatic driving system due to the special running scene, common time synchronization methods include synchronizing the automatic driving controller and the laser radar by using the NTP service, or realizing the time synchronization of the automatic driving controller by using the GPS time service.

[0003] The NTP time synchronization is a time synchronization network technology, which refers to that a system synchronizes time with another system by using the NTP service.

[0004] The NTP service is used for synchronization, the internal SOCs of the automatic driving controller are synchronized with the main SOC by using the NTP service, and the laser radar is also synchronized with the main SOC of the automatic driving controller by using the NTP service, and the time accuracy completely depends on the network, and in the case that the network load is high, the delay can even reach seconds, so that the error is obvious.

[0005] The GPS time service refers to that the system obtains the time by adding the GPRMC time and the counting time after the PPS is cleared.

[0006] The GPS output by the inertial navigation system is used for time service, the time synchronization of the automatic driving controller and the laser radar is realized, when the GPS signal is disturbed, the system time will be disordered, and the automatic driving is affected. SUMMARY

[0007] The application provides an automatic driving system time synchronization system of an unmanned container truck, which aims to solve the problem that the prior art cannot guarantee the time automatic synchronization accuracy of the automatic driving domain controller and devices such as multiple laser radars and visual identification cameras. Meanwhile, the application also aims to solve the problem that the system time of the automatic driving domain controller cannot be automatically recovered in the case of GPS abnormality.

[0008] The technical scheme adopted by the application is as follows:

[0009] An automatic driving system time synchronization system of an unmanned container truck, comprising: an automatic driving domain controller, a camera, an inertial navigation system and a laser radar, wherein:

[0010] The camera and the automatic driving domain controller are connected through an MIPI interface;

[0011] The inertial navigation system and the automatic driving domain controller are connected through an RS232 serial port line;

[0012] The laser radar is connected with an automatic driving domain controller through an RS232 serial port line.

[0013] The automatic driving domain controller is internally provided with a main SOC and a secondary SOC.

[0014] As a preference, the camera is 7-9.

[0015] As a preference, the laser radar is 7-9.

[0016] As a preference, the automatic driving domain controller and the laser radar both have internal clock sources, and the accuracy requirement standard is 24 hours, and the standard time error is not more than 1 second.

[0017] The application also provides a time synchronization method of an automatic driving system of an unmanned container truck.

[0018] Step 1, in the initial stage of system power-on, when no GPRMC and PPS signals from the inertial navigation system are received, the main SOC still uses the internal clock source time, the secondary SOC uses NTP service to synchronize with the main SOC, and the laser radar uses NTP service to synchronize with the main SOC.

[0019] Step 2, after the automatic driving domain controller first acquires the GPRMC and PPS signals, GPRMC verification is performed, if the verification is passed, all systems use GPS for time service, otherwise, the internal clock source time is continued to be used.

[0020] Step 3, the automatic driving domain controller continuously performs NTP service synchronization at a frequency of once per minute, and continuously acquires GPRMC and PPS signals.

[0021] Step 4, when the system is powered off, the secondary SOC has no RTC battery power supply, and has no system time, the main SOC has an RTC battery power supply, and the acquired time is the internal clock source time, and the laser radar has an RTC battery power supply, and the acquired time is the internal clock source time.

[0022] As a preference, in the step 2, further comprising:

[0023] Step 21, after the automatic driving domain controller receives the GPRMC and PPS signals, the automatic driving domain controller MCU analyzes the GPRMC signals.

[0024] Step 22, the automatic driving domain controller sends the analyzed GPRMC and PPS signals to the main SOC and the secondary SOC through UDP, and simultaneously, the internal CPLD of the automatic driving domain controller divides the PPS signals to the main SOC and the secondary SOC by using a hard-wired signal.

[0025] Step 23, the main SOC and the secondary SOC first receive the time sent by the CPLD, and then add the UTC time sent by the UDP to obtain the complete system time.

[0026] As preferred, in the step 22, the GPRMC is forwarded to the laser radar by multiple RS232 chips inside the automatic driving domain controller, the PPS signal is distributed to the laser radar by the CPLD, and the laser radar acquires the GPRMC and the PPS signal to perform GPS time service.

[0027] As preferred, in the step 2, the camera time adopts the automatic driving domain controller time when the automatic driving domain controller acquires the image time, and the time synchronization of the inertial navigation system, the automatic driving domain controller, the laser radar and the camera is ensured.

[0028] As preferred, the laser radar collects at a frequency of 10HZ after receiving the PPS signal, and the CPLD signal is sent after the PPS signal with a delay of 5ms, so that the laser radar and the camera collect at the same time and at the same place.

[0029] The present application has the following beneficial effects:

[0030] 1. By the distribution of the CPLD inside the controller, the PPS is distributed to the main SOC and the secondary SOC, the GPRMC signal is sent to the multiple laser radars by multiple RS232 chips, and the GPRMC is sent to the main SOC and the secondary SOC by the UDP, so that the time synchronization of the automatic driving domain controller and the multiple laser radars is solved.

[0031] 2. By the double clock source setting, in the case of abnormal GPS time service, the internal clock source is adopted and the NTP service is used for synchronization, and in the case of normal GPS time service, the GPS time service is adopted, so that the problem of abnormal system time in the case of abnormal GPS is solved. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is the architecture diagram of the system of the present application;

[0033] Figure 2 It is the brief flow chart of the method of the present application;

[0034] Figure 3 It is the detailed flow chart of the method of the present application;

[0035] Figure 4 It is the step flow chart of the method of the present application. DETAILED DESCRIPTION

[0036] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0037] As shown in Figure 1 The embodiment provides an unmanned container truck automatic driving system time synchronization system, which comprises an automatic driving domain controller, a camera, an inertial navigation system and a laser radar, wherein: the camera is connected with the automatic driving domain controller through an MIPI interface;

[0038] The inertial navigation system is connected with the automatic driving domain controller through an RS232 serial port line, and the inertial navigation system outputs one GPRMC / PPS to the automatic driving domain controller;

[0039] The laser radar is connected with the automatic driving domain controller through an RS232 serial port line, and the automatic driving outputs eight GPRMC / PPS signals to the laser radar.

[0040] The automatic driving domain controller is internally provided with a main SOC and a secondary SOC.

[0041] The camera is 7, and a camera deserializing chip 96712 is internally provided in the camera to realize time control.

[0042] Further, the laser radar is 9.

[0043] Further, the automatic driving domain controller and the laser radar are both internally provided with a clock source, and the accuracy requirement standard is 24 hours, and the standard time error is not more than 1 second.

[0044] As shown in Figure 2 , Figure 3 The embodiment also provides an unmanned container truck automatic driving system time synchronization method, which comprises:

[0045] In step S1, when the system is powered on initially and the GPRMC and PPS signals sent by the inertial navigation system are not received, the main SOC still uses an internal clock source time, the secondary SOC uses NTP service to synchronize with the main SOC, and the laser radar uses NTP service to synchronize with the main SOC;

[0046] In step S2, after the automatic driving domain controller first acquires the GPRMC and PPS signals, GPRMC verification is performed, if the verification is passed, all systems use GPS for time service, otherwise, the internal clock source time is continued to be used;

[0047] Step S3, the autonomous driving domain controller continues to conduct NTP service synchronization at a frequency of once per minute, continuously obtains GPRMC and PPS signals;

[0048] Step S4, the system is powered off, the secondary SOC is internally powered by an RTC battery and has no system time, the primary SOC is internally powered by an RTC battery and obtains time as an internal clock source time, and the laser radar is internally powered by an RTC battery and obtains time as an internal clock source time.

[0049] Further, in the step S1, it is ensured that the system can also maintain time synchronization under the premise of no GPS time in the initial power-on period.

[0050] Further, as shown in the step S2, it also includes: Figure 4

[0051] Step S21, after the autonomous driving domain controller receives the GPRMC and PPS signals, the autonomous driving domain controller MCU analyzes the GPRMC signal;

[0052] Step S22, the autonomous driving domain controller sends the analyzed GPRMC and PPS signals to the primary SOC and the secondary SOC through UDP, and at the same time, the autonomous driving domain controller internal CPLD uses a hard-wired signal to distribute the PPS signal to the primary SOC and the secondary SOC;

[0053] The signal transmitted by the CPLD has a transmission speed in the order of nanoseconds, and this signal will arrive at the primary SOC and the secondary SOC earlier than the GPRMC time sent by UDP, and will clear the internal timing and start accumulation first;

[0054] Step S23, the primary SOC and the secondary SOC first receive the time sent by the CPLD, and after receiving the UTC time sent by UDP, the two are added to obtain the complete system time.

[0055] Further, in the step S22, the autonomous driving domain controller internally forwards the GPRMC to the laser radar through multiple RS232 chips, and distributes the PPS signal to the laser radar through the CPLD, and the laser radar obtains the GPRMC and PPS signals and performs GPS time service.

[0056] Further, in the step S2, the camera time adopts the autonomous driving domain controller time when the autonomous driving domain controller obtains the image time, to ensure the time synchronization of the inertial navigation system, the autonomous driving domain controller, the laser radar, and the camera.

[0057] ​Further, the laser radar collects at a frequency of 10HZ after receiving the PPS signal, and the CPLD signal is sent after the PPS signal delays for 5 milliseconds, so as to ensure that the laser radar and the camera collect at the same time and the same place.

[0058] Further, as long as the automatic driving system is powered on, the CPLD keeps the PPS output, and the PPS is used as a timing zero reset and a collection trigger signal of the laser radar and the camera; the laser radar starts scanning after receiving the rising edge of the PPS, and collects at a frequency of 10HZ.

[0059] Further, the laser radar collection is a rotating scanning type, so as to ensure that the data collected by the camera and the radar are images at the same time and the same place; when the radar scans the camera direction, the camera needs to be exposed immediately, and the trigger signal of the camera exposure is a camera sync, so that the camera synchronization signal output by the CPLD is sent after the PPS delays for 5 milliseconds, so as to ensure that the radar and the camera collect at the same time and the same place.

[0060] The terms involved in the application are explained as follows:

[0061] GPS time service: The GPS satellite is equipped with a high-precision atomic clock. The principle of GPS time service is that the GPS receiver can receive signals of >=4 satellites in its field of view at any time, and after decoding and processing, two kinds of time signals are extracted and output: A. A synchronous pulse signal PPS (Pulse Per Second, second pulse) with a time interval of 1S and a pulse width of 5ms-100ms, and the synchronization error of the pulse front edge with the international standard time is <1us. After the system receives the rising edge signal of the PPS, the internal timing is cleared and re-counted; B. The information output by the serial port is the international standard time and date corresponding to the PPS front edge, and the most widely used is the NMEA-0183 protocol, such as $GPRMC. GPRMC is a standard format message containing UTC time (accurate to seconds), latitude and longitude positioning data.

[0062] UTC: Coordinated Universal Time, also known as World Standard Time, World Standard Time, International Coordination Time.

[0063] The above embodiment numbers of the application are only for description, and do not represent the advantages and disadvantages of the embodiments. The embodiments of the application are described above in combination with the drawings, but the application is not limited to the above specific embodiments, and the above specific embodiments are only illustrative, but not limiting. Those skilled in the art can make many forms without departing from the purpose of the application and the scope protected by the claims under the inspiration of the application, and these all belong to the protection of the application.

Claims

1. A time synchronization method for an unmanned truck automatic driving system, comprising: Step 1: During the initial power-up phase, the system includes an autonomous driving domain controller, a camera, an inertial navigation system (INS), and a lidar. The camera is connected to the autonomous driving domain controller via a MIPI interface, the INS is connected to the autonomous driving domain controller via an RS232 serial cable, and the lidar is connected to the autonomous driving domain controller via an RS232 serial cable. The autonomous driving domain controller has a built-in primary SOC and a secondary SOC. When the INS does not receive GPRMC and PPS signals, the primary SOC still uses its internal clock source time, the secondary SOC uses NTP service to synchronize with the primary SOC, and the lidar uses NTP service to synchronize with the primary SOC. Step 2: After the autonomous driving domain controller acquires the GPRMC and PPS signals for the first time, it performs GPRMC verification. If the verification passes, the entire system uses GPS for time synchronization; otherwise, it continues to use the internal clock source time. Step 3: The autonomous driving domain controller continuously performs NTP service synchronization at a frequency of once per minute, and continuously acquires GPRMC and PPS signals; Step 4: The system is powered down. The secondary SOC has no RTC battery power and no system time. The main SOC has an RTC battery power and the time obtained is the internal clock source time. The lidar has an RTC battery and the time obtained is the internal clock source time. Step 2 also includes: Step 21: After receiving the GPRMC and PPS signals, the autonomous driving domain controller MCU parses the GPRMC signal. Step 22: The automated driving domain controller sends the parsed GPRMC and PPS signals to the primary SOC and secondary SOC via UDP. At the same time, the CPLD inside the automated driving domain controller uses hard-wired signals to distribute the PPS signal to the primary SOC and secondary SOC. Step 23: The main SOC and the secondary SOC first receive the time sent by the CPLD, and then add the two times to obtain the complete system time after receiving the UTC time sent by the UDP. In step 22, the autonomous driving domain controller forwards the GPRMC to the lidar through multiple RS232 chips and distributes the PPS signal to the lidar through the CPLD. After the lidar acquires the GPRMC and PPS signals, it performs GPS timing.

2. The time synchronization method for an unmanned truck automatic driving system as described in claim 1, characterized in that, In step 2, the camera time is obtained using the autopilot domain controller time at the moment the image is acquired, ensuring time synchronization of the inertial navigation system, autopilot domain controller, LiDAR, and camera.

3. The time synchronization method for an unmanned truck automatic driving system as described in claim 1, characterized in that, After receiving the PPS signal, the lidar collects data at a frequency of 10Hz. The CPLD signal is sent 5 milliseconds after the PPS signal to ensure that the lidar and the camera collect data at the same time and location.

4. The time synchronization method for an unmanned truck automatic driving system as described in claim 1, characterized in that, Both the autonomous driving domain controller and the LiDAR have internal clock sources, and the accuracy requirement is 24 hours, with a standard time error of no more than 1 second.

5. The time synchronization method for an unmanned truck automatic driving system as described in claim 1, characterized in that, The number of cameras is 7-9.

6. The time synchronization method for an unmanned truck automatic driving system as described in claim 1, characterized in that, The number of lidar units is 7-9.

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