CN111007554A - Data acquisition time synchronization system and method - Google Patents
Data acquisition time synchronization system and method Download PDFInfo
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- CN111007554A CN111007554A CN201911264923.7A CN201911264923A CN111007554A CN 111007554 A CN111007554 A CN 111007554A CN 201911264923 A CN201911264923 A CN 201911264923A CN 111007554 A CN111007554 A CN 111007554A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
- G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/42—Determining position
- G01S19/45—Determining position by combining measurements of signals from the satellite radio beacon positioning system with a supplementary measurement
- G01S19/47—Determining position by combining measurements of signals from the satellite radio beacon positioning system with a supplementary measurement the supplementary measurement being an inertial measurement, e.g. tightly coupled inertial
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C21/00—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00
- G01C21/10—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 by using measurements of speed or acceleration
- G01C21/12—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 by using measurements of speed or acceleration executed aboard the object being navigated; Dead reckoning
- G01C21/16—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 by using measurements of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation
- G01C21/165—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 by using measurements of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation combined with non-inertial navigation instruments
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Abstract
The embodiment of the invention provides a data acquisition time synchronization system and a data acquisition time synchronization method, and relates to the technical field of mobile mapping. The method and the device synchronize the GPS time contained in the GPS signal to the system time of a data acquisition time synchronization system by taking the GPS pulse per second signal as a time synchronization reference when receiving the GPS signal and the GPS pulse per second signal transmitted by the GNSS receiver, generate an internal pulse per second signal when not receiving the GPS signal and the GPS pulse per second signal transmitted by the GNSS receiver, and update the preset initial time by taking the internal pulse per second signal as a reference to obtain the system time of the data acquisition time synchronization system, thereby controlling the data acquisition time synchronization of a plurality of data acquisition modules according to the system time and obtaining the synchronized navigation data. Under the condition of GPS signals or no GPS signals, the system time is updated according to the pulse per second signals, so that the accuracy of the system time is ensured, accurate time and position information can be obtained, and the stability of the system is enhanced.
Description
Technical Field
The invention relates to the technical field of mobile mapping, in particular to a data acquisition time synchronization system and a data acquisition time synchronization method.
Background
The mobile measurement has wide application in the surveying and mapping field, and is the main development flow in the future road electronic map surveying and mapping field, three-dimensional measurement and modeling field. A complete mobile measurement System should include a laser scanner, a panoramic camera, a GNSS (global navigation Satellite System) module, an inertia module, a odometer, a time synchronization controller, a data acquisition and storage device, and the like. The design of the time synchronization controller directly influences the resolving precision of the measured data, and particularly in the field of precise mobile mapping, the design of a high-accuracy time synchronization control system is particularly important. If the data time is not properly processed, the data acquisition is invalid or the error is too large. Wherein, the error in time synchronization can cause the point cloud collected by the laser scanner to be distorted, inclined and deformed; causing the combination of the inertial data collected by the inertial module and the GPS data collected by the Global Positioning System (GPS) module to fail; in the same way, the images collected by the panoramic camera cannot be registered to the point cloud, and the panoramic measurement cannot be accurately performed. In short, the desired measurement effect cannot be achieved.
Therefore, for the mobile measurement system, it is significant to perform accurate time synchronization work on the data acquired by each sensor.
Disclosure of Invention
In view of the above, the present invention provides a data acquisition time synchronization system and method to achieve time synchronization of data of multiple sensors.
In order to achieve the above purpose, the embodiment of the present invention adopts the following technical solutions:
in a first aspect, an embodiment provides a data acquisition time synchronization system, where the data acquisition time synchronization system includes a GNSS receiver, a time synchronization controller, and a plurality of data acquisition modules, and the GNSS receiver, the time synchronization controller, and the plurality of data acquisition modules are sequentially connected;
the GNSS receiver is used for acquiring a GPS signal and transmitting the GPS signal and a GPS second pulse signal to the time synchronization controller;
the time synchronization controller is used for synchronizing the GPS time contained in the GPS signal to the system time of the data acquisition time synchronization system by taking the GPS second pulse signal as a time synchronization reference when the GPS signal and the GPS second pulse signal transmitted by the GNSS receiver are received;
the time synchronization controller is also used for generating an internal pulse-per-second signal when the GPS signal and the GPS pulse-per-second signal transmitted by the GNSS receiver are not received, and updating the preset initial time by taking the internal pulse-per-second signal as a reference so as to obtain the system time of the data acquisition time synchronization system;
the time synchronization controller is also used for controlling the data acquisition time synchronization of the data acquisition modules according to the system time to obtain the synchronized navigation data.
In an optional embodiment, the data acquisition module comprises an inertial measurement unit, the synchronous navigation data comprises an attitude data frame, and the inertial measurement unit is electrically connected with the time synchronization controller;
the inertia measurement unit is used for acquiring attitude information;
the time synchronization controller is used for acquiring attitude information when detecting the effective edge of an attitude information synchronization signal transmitted by the inertia measurement unit;
the time synchronization controller is also used for recording a first sampling time and a second sampling time, wherein the first sampling time is the time when sampling starts, and the second sampling time is the time when sampling ends;
the time synchronization controller is further used for packing the attitude information, the first sampling time and the second sampling time to obtain an attitude data frame.
In an alternative embodiment, the data acquisition module comprises a camera device, the synchronized navigation data comprises frames of image data, and the camera device is electrically connected with the time synchronization controller;
the time synchronization controller is used for generating a photographing trigger pulse by taking a preset minimum photographing time gap as a period so as to control the photographing equipment to photograph;
the time synchronization controller is also used for recording a third sampling time and the serial number of the photographing trigger pulse, wherein the third sampling time is the time for sending the photographing trigger pulse;
and the time synchronization controller is also used for packing the third sampling time and the sequence number to obtain the image data frame.
In an optional embodiment, the data acquisition module comprises an encoder, the synchronized navigation data comprises an encoder data frame, and the encoder is electrically connected with the time synchronization controller;
the time synchronization controller is used for acquiring phase pulse signals of the encoder according to a preset time period and counting the phase pulse signals in each time period to obtain the pulse number;
the time synchronization controller is further configured to record a fourth sampling time and a fifth sampling time, and pack the fourth sampling time, the fifth sampling time and the pulse number to obtain an encoder data frame, where the fourth sampling time and the fifth sampling time are a start time and an end time of a time period, respectively.
In an optional embodiment, the time synchronization controller is configured to count the received GPS pulse-per-second signal to obtain a count value when receiving the GPS signal and the GPS pulse-per-second signal transmitted by the GNSS receiver;
and the time synchronization controller is also used for updating the system time of the data acquisition time synchronization system to the GPS time contained in the GPS signal and clearing the count value when the count value is the first threshold value.
In a second aspect, an embodiment provides a data acquisition time synchronization method, which is applied to a time synchronization controller of a data acquisition time synchronization system, where the data acquisition time synchronization system further includes a GNSS receiver and a plurality of data acquisition modules, and the GNSS receiver, the time synchronization controller and the plurality of data acquisition modules are sequentially connected, and the method includes:
when a GPS signal and a GPS pulse per second signal transmitted by a GNSS receiver are received, the GPS pulse per second signal is used as a time synchronization reference to synchronize the GPS time contained in the GPS signal to the system time of a data acquisition time synchronization system;
when the GPS signal and the GPS pulse per second signal transmitted by the GNSS receiver are not received, generating an internal pulse per second signal, and updating preset initial time by taking the internal pulse per second signal as a reference to obtain the system time of the data acquisition time synchronization system;
and controlling the data acquisition time synchronization of the data acquisition modules according to the system time to obtain the synchronous navigation data.
In an optional embodiment, the data acquisition module includes an inertial measurement unit, the synchronized navigation data includes an attitude data frame, the data acquisition time synchronization of the plurality of data acquisition modules is controlled according to the system time, and the step of obtaining the synchronized navigation data includes:
acquiring attitude information when detecting an effective edge of an attitude information synchronization signal transmitted by an inertial measurement unit;
recording a first sampling time and a second sampling time, wherein the first sampling time is the time when sampling starts, and the second sampling time is the time when sampling ends;
and packaging the attitude information, the first sampling time and the second sampling time to obtain an attitude data frame.
In an alternative embodiment, the data acquisition module comprises a camera device, the synchronized navigation data comprises frames of image data, the data acquisition time synchronization of the plurality of data acquisition modules is controlled according to the system time, and the step of obtaining the synchronized navigation data comprises:
generating a photographing trigger pulse by taking a preset minimum photographing time gap as a period so as to control photographing equipment to photograph;
recording third sampling time and the serial number of the photographing trigger pulse, wherein the third sampling time is the time for sending the photographing trigger pulse;
and packaging the third sampling time and the sequence number to obtain an image data frame.
In an optional embodiment, the data acquisition module includes an encoder, the synchronized navigation data includes an encoder data frame, the data acquisition time synchronization of the plurality of data acquisition modules is controlled according to the system time, and the step of obtaining the synchronized navigation data includes:
acquiring phase pulse signals of an encoder according to a preset time period, and counting the phase pulse signals in each time period to obtain the number of pulses;
and recording a fourth sampling time and a fifth sampling time, and packaging the fourth sampling time, the fifth sampling time and the pulse number to obtain an encoder data frame, wherein the fourth sampling time and the fifth sampling time are respectively a start time and an end time of a time period.
In an alternative embodiment, the step of synchronizing the GPS time contained in the GPS signal to the system time of the data acquisition time synchronization system using the GPS second pulse signal as the time synchronization reference includes:
counting the received GPS second pulse signal to obtain a count value;
when the counting value is a first threshold value, updating the system time of the data acquisition time synchronization system to the GPS time contained in the GPS signal;
and clearing the count value.
According to the data acquisition time synchronization system and method provided by the embodiment of the invention, when the GPS signal and the GPS pulse per second signal transmitted by the GNSS receiver are received, the GPS time contained in the GPS signal is synchronized to the system time of the data acquisition time synchronization system by taking the GPS pulse per second signal as a time synchronization reference, when the GPS signal and the GPS pulse per second signal transmitted by the GNSS receiver are not received, an internal pulse per second signal is generated, and the preset initial time is updated by taking the internal pulse per second signal as a reference to obtain the system time of the data acquisition time synchronization system, so that the data acquisition time synchronization of a plurality of data acquisition modules is controlled according to the system time, and the synchronized navigation data is obtained. Under the condition of GPS signals or no GPS signals, the system time is updated according to the pulse per second signals, so that the accuracy of the system time is ensured, accurate time and position information can be obtained, and the stability of the system is enhanced.
In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
Fig. 1 shows a block diagram of a circuit structure of a data acquisition time synchronization system according to an embodiment of the present invention.
Fig. 2 is a block diagram illustrating a further circuit structure of the data acquisition time synchronization system according to the embodiment of the present invention.
Fig. 3 shows a timing diagram of the synchronization of the GPS time contained in the GPS signal to the system time of the data acquisition time synchronization system with the GPS second pulse signal as a time synchronization reference.
Fig. 4 is a diagram illustrating logic units inside the time synchronization controller according to the embodiment of the present invention.
FIG. 5 shows a timing diagram of the acquisition process of pose information.
Fig. 6 shows a flow chart of the data acquisition time synchronization method provided by the present invention.
Fig. 7 shows a further flowchart of S603 when an IMU is acquired synchronously.
Fig. 8 shows a further flowchart of S603 when performing synchronous acquisition on the camera device.
Fig. 9 shows a further flowchart of S603 when the encoder is synchronously acquired.
Icon: 100-data acquisition time synchronization system; 110-a time synchronization controller; 120-a GNSS receiver; 130-a data acquisition module; 131-an inertial measurement unit; 132-an encoder; 133-a photographic device; 134-scanner.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
It is noted that relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
At present, a plurality of sensors exist in a mobile measurement system, and data synchronization is needed, so that the realization difficulty is high. In the prior art, the methods generally adopted are as follows:
first, a combined navigation system is simply used for data synchronization control, such as APX15 of the company Applanix, N580 of the company Honeywell, SPAN-CPT of the company NovAtel, and the like, which are combined navigation products, can be used as time synchronization signals of vehicle-mounted and airborne mobile measurement products, and can also record accurate time stamps of external trigger signals, but the connected equipment is limited and expensive.
And the second method comprises the following steps: and a GNSS board card with rich interfaces is adopted for time synchronization. Although the GNSS board card can perform time synchronization processing on data acquired by a plurality of external devices to a certain extent, the inertial module device matched with the GNSS board card is generally expensive, and accurate time and position information cannot be acquired if the GPS signal is in an unlocked state.
And the third is that: the GNSS board card and the synchronous control system are adopted to cooperatively perform time processing, a single chip microcomputer hardware chip is utilized to acquire GPS time, a set of time system is operated in the single chip microcomputer chip, an external sensor is directly connected into the single chip microcomputer chip, and the time synchronization processing of data is performed through the time system in the single chip microcomputer. However, the execution of the common singlechip system or ARM system program is the flow operation from top to bottom, and even in an interrupt processing or multithreading mode, a little uncontrollable time delay exists, so the control mode has the problem of insufficient time precision, and the precision of the equipment is influenced in the fields of high-precision map measurement and three-dimensional laser measurement.
First embodiment
The embodiment of the invention provides a data acquisition time synchronization system 100 to realize time synchronization of data of a plurality of sensors. Fig. 1 is a block diagram of a circuit structure of a data acquisition time synchronization system 100 according to the present invention. The data acquisition time synchronization system 100 includes a GNSS receiver 120, a time synchronization controller 110, and a plurality of data acquisition modules 130, wherein the GNSS receiver 120, the time synchronization controller 110, and the plurality of data acquisition modules 130 are sequentially connected.
Referring to fig. 2, a block diagram of a further circuit structure of the data acquisition time synchronization system 100 according to the present invention is shown. The data acquisition module 130 may be an Inertial Measurement Unit (IMU) 131, a camera 133, an encoder 132, a scanner 134, and the like.
The GNSS receiver 120 may acquire a GPS signal through an antenna and transmit the GPS signal and the GPS second pulse signal to the time synchronization controller 110.
It should be noted that the GPS signal may be transmitted to the time synchronization controller 110 by a National Marine Electronics Association (NMEA) protocol. The GPS signals include location signals (e.g., latitude and longitude information, etc.), time signals, and the like.
The GPS Pulse Per Second (PPS) signal is a PPS signal output from the GNSS receiver 120, and is used to calibrate the GPS time.
The time synchronization controller 110 is configured to calibrate the system time and provide a time reference for the inertial measurement unit 131, the camera device 133, the encoder 132, and the scanner 134, so as to implement time synchronization of data acquisition; meanwhile, the time synchronization controller 110 is also used for implementing complex logic relation operations, such as instruction response, data format conversion, data packing, and the like.
In this embodiment, the time synchronization controller 110 can be implemented by a Field Programmable Gate Array (FPGA).
The time synchronization controller 110 is configured to synchronize the GPS time contained in the GPS signal to the system time of the data acquisition time synchronization system 100 by using the GPS second pulse signal as a time synchronization reference when receiving the GPS signal and the GPS second pulse signal transmitted by the GNSS receiver 120.
Specifically, the time synchronization controller 110 is configured to count the received GPS second pulse signal to obtain a count value when receiving the GPS signal and the GPS second pulse signal transmitted by the GNSS receiver 120, and is configured to update the system time of the data acquisition time synchronization system 100 to the GPS time included in the GPS signal and clear the count value when the count value is the first threshold.
For example, when receiving the GPS signal and the GPS pulse-per-second signal for the first time, the time synchronization controller 110 synchronizes the GPS time included in the GPS signal to the system time, and starts to count the received GPS pulse-per-second signal to obtain a count value, and if the count value is detected to be 10 (i.e., 10 PPS signals are continuously detected), the time synchronization controller clears the microsecond timer at the time of the tenth PPS signal and writes the GPS time in the current state, thereby completing the whole-second writing and also completing the whole-second calibration of the system time according to the PPS signal. As shown in fig. 3, the time points T1 and T3 are the detection points of the first two PPS signals. If 10 PPS signals are detected, i.e. at time T4 in the figure, the microsecond register of the time synchronization controller 110 at that time is cleared, the time information of the GPS accurate to the second immediately after the 9 th PPS signal detection point is written into the time register of the time synchronization controller 110, and the microsecond register is cleared at time T4, and the time stored in the microsecond register is added by 1, thereby completing the calibration of the acquisition of the GPS time and the whole second.
The time synchronization controller 110 is further configured to generate an internal pulse-per-second signal when the GPS signal and the GPS pulse-per-second signal transmitted by the GNSS receiver 120 are not received, and update the preset initial time with the internal pulse-per-second signal as a reference to obtain the system time of the data acquisition time synchronization system 100.
Specifically, please refer to fig. 4, which is a logic unit diagram inside the time synchronization controller 110. When the GNSS receiver 120 normally operates, the PPS signal detection unit inside the time synchronization controller 110 may be used to detect the GPS pulse-per-second signal, and the NIOS II soft core inside the time synchronization controller 110 is used to analyze the GPS signal to obtain GPS time, and then the system time synchronization unit inside the time synchronization controller 110 synchronizes the system time; when the GPS signal and the PPS signal cannot be normally received, an internal pulse-per-second signal may be generated by a Phase-Locked Loop (PLL) frequency multiplication unit inside the time synchronization controller 110, and then a system time synchronization unit inside the time synchronization controller 110 updates preset initial time by using the internal pulse-per-second signal as a reference to obtain system time of the data acquisition time synchronization system 100.
It should be noted that the PPS signal detection unit and the system time synchronization unit can be implemented by a hardware description language Verilog HDL.
It should be noted that the preset initial time can be set by the NIOS II soft core inside the FPGA. Meanwhile, in other embodiments, the PPS Signal detection circuit, the system time synchronization circuit, and other circuits may be implemented by logic circuits, and the NIOS II soft core inside the FPGA may be replaced by a device having data Processing capability, such as a Digital Signal Processing (DSP).
The inertial measurement unit 131 is used to collect attitude information. The attitude information includes angular velocity information and acceleration information. It should be noted that the inertial measurement unit 131 transmits the attitude information and also transmits an attitude information synchronization signal, and the time synchronization controller 110 can acquire the attitude information only during the period in which the attitude information synchronization signal is valid.
Therefore, the time synchronization controller 110 is configured to acquire the attitude information when detecting the valid edge of the attitude information synchronization signal transmitted by the inertial measurement unit 131.
The valid edge may be a rising edge of the attitude information synchronization signal or a falling edge of the attitude information synchronization signal, and the user may set the valid edge through the inertia measurement unit 131.
The time synchronization controller 110 is further configured to record the first sampling time and the second sampling time, and pack the attitude information, the first sampling time, and the second sampling time to obtain an attitude data frame. The first sampling time is the time when sampling starts, and the second sampling time is the time when sampling ends.
Please refer to fig. 5, which is a timing chart of the process of acquiring the attitude information. The rising edge of the attitude information synchronization signal is valid, so that the time synchronization controller 110 records the time T at the moment when the rising edge of the attitude information synchronization signal is collectedimu', and from Timu"begin to collect attitude information at time TimuThe' moment ends the acquisition. Meanwhile, the acquisition of attitude information is realized by a Verilog hardware part of the FPGA, and the attitude information T is delivered to an NIOS II of the FPGAimu"and Timu"' is packed into a frame of pose data.
When the data synchronous acquisition of the camera device 133 is required, the time synchronization controller 110 is configured to generate a photographing trigger pulse to control the camera device 133 to photograph in a period of a preset minimum photographing time interval.
The time synchronization controller 110 is further configured to record a third sampling time and a sequence number of the photographing trigger pulse, and package the third sampling time and the sequence number to obtain an image data frame. And the third sampling time is the time for sending the photographing trigger pulse.
For example, the minimum photographing time interval of the photographing apparatus 133 is 100ms, which indicates that 10 photographs can be taken within 1s thereof. Thus, the time synchronization controller 110 can generate the photo trigger signal with the cycle of 100ms by using PLL frequency multiplication, and the photographing device 133 performs photographing every time the time synchronization controller 110 generates one photo trigger. At this time, the sending time of the photographing trigger pulse (namely, the third sampling time) is recorded, the serial number of the photographing trigger pulse (the serial number representing the photo) is recorded, and then the third sampling time and the serial number are packaged to obtain the image data frame.
It should be noted that the camera device 133 may be a panoramic camera or a general camera.
When the data synchronous acquisition of the encoder 132 is required, the time synchronization controller 110 is configured to acquire the phase pulse signal of the encoder 132 according to a preset time period, and count the phase pulse signal in each time period to obtain the number of pulses.
The time synchronization controller 110 is further configured to record a fourth sampling time and a fifth sampling time, and pack the fourth sampling time, the fifth sampling time, and the pulse number to obtain a data frame of the encoder 132, where the fourth sampling time and the fifth sampling time are a start time and an end time of a time period, respectively.
Generally, the pulse encoder 132 includes A, B, Z three phases, and the pulse encoder 132 outputs an a-phase pulse signal and a B-phase pulse signal to the time synchronization controller 110 simultaneously. The time synchronization controller 110 collects the a-phase pulse signal and the B-phase pulse signal at the same time, so that the upper computer can determine whether the pulse encoder 132 rotates forward or backward according to the phase information of the a-phase pulse signal and the B-phase pulse signal, and calculate the speed and the travel distance of the target in unit time according to the accumulated number of pulses.
Specifically, the time-axis time T of the rising edge of the a-phase pulse signal is acquired by the time synchronization controller 110dmiA, and collecting the time T of the rising edge of a B-phase pulse signal following the high level of the A-phase pulse signaldmiB, if TdmiThe A-phase pulse signal corresponding to the B time is high level, which indicates positive rotation, if the signal is high level, the signal is positive rotationIf TdmiThe a-phase pulse signal corresponding to the B-time is low level, indicating inversion.
Meanwhile, the present invention can also use the time synchronization controller 110 to realize one-to-many GPS signals and GPS second pulse signals, so as to simultaneously access a plurality of scanners 134, thereby effectively increasing the number of sensor devices accessed.
Second embodiment
The invention also provides a data acquisition time synchronization method, which is applied to the time synchronization controller 110 of the data acquisition time synchronization system 100. Please refer to fig. 6, which is a flowchart illustrating a data acquisition time synchronization method according to the present invention. The data acquisition time synchronization method comprises the following steps:
s601, when receiving the GPS signal and the GPS pulse-per-second signal transmitted by the GNSS receiver 120, synchronizing the GPS time included in the GPS signal to the system time of the data acquisition time synchronization system 100 by using the GPS pulse-per-second signal as a time synchronization reference.
Specifically, when receiving the GPS signal and the GPS second pulse signal transmitted by the GNSS receiver 120, the GNSS receiver counts the received GPS second pulse signal to obtain a count value; when the count value is a first threshold value, updating the system time of the data acquisition time synchronization system 100 to the GPS time contained in the GPS signal; and clearing the count value.
S602, when the GPS signal and the GPS pulse-per-second signal transmitted by the GNSS receiver 120 are not received, generating an internal pulse-per-second signal, and updating the preset initial time with the internal pulse-per-second signal as a reference to obtain the system time of the data acquisition time synchronization system 100.
S603, controlling the data acquisition time synchronization of the data acquisition modules 130 according to the system time to obtain the synchronized navigation data.
If the IMU is synchronously acquired, please refer to fig. 7, and S603 includes:
s6031, when the valid edge of the attitude information synchronization signal transmitted by the inertia measurement unit 131 is detected, the attitude information is acquired.
S6032, record the first sampling time and the second sampling time.
The first sampling time is the time when sampling starts, and the second sampling time is the time when sampling ends.
And S6033, packaging the attitude information, the first sampling time and the second sampling time to obtain an attitude data frame.
If the phase device 133 is synchronously acquired, referring to fig. 8, S603 includes:
s6034, a photographing trigger pulse is generated with a preset minimum photographing time interval as a period to control the photographing apparatus 133 to perform photographing.
And S6035, recording the third sampling time and the serial number of the photographing trigger pulse.
And the third sampling time is the time for sending the photographing trigger pulse.
And S6036, packaging the third sampling time and the sequence number to obtain an image data frame.
If the encoder 132 is synchronously acquired, referring to fig. 9, S603 includes:
s6037, acquiring the phase pulse signal of the encoder 132 according to a preset time period, and counting the phase pulse signal in each time period to obtain the number of pulses.
S6038, record the fourth sampling time and the fifth sampling time, and pack the fourth sampling time, the fifth sampling time, and the pulse number to obtain the encoder 132 data frame.
The fourth sampling time and the fifth sampling time are respectively the starting time and the ending time of a time period.
In summary, the data acquisition time synchronization system and method provided in the embodiments of the present invention synchronize the GPS time contained in the GPS signal to the system time of the data acquisition time synchronization system by using the GPS second pulse signal as a time synchronization reference when receiving the GPS signal and the GPS second pulse signal transmitted by the GNSS receiver, generate the internal second pulse signal when not receiving the GPS signal and the GPS second pulse signal transmitted by the GNSS receiver, and update the preset initial time by using the internal second pulse signal as a reference to obtain the system time of the data acquisition time synchronization system, thereby controlling the data acquisition time synchronization of the plurality of data acquisition modules according to the system time to obtain the synchronized navigation data. Under the condition of GPS signals or no GPS signals, the system time is updated according to the pulse per second signals, so that the accuracy of the system time is ensured, accurate time and position information can be obtained, and the stability of the system is enhanced.
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 invention. 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, the functional modules in the embodiments of the present invention 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 solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes 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 method according to the embodiments of the present invention. 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.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A data acquisition time synchronization system is characterized by comprising a GNSS receiver, a time synchronization controller and a plurality of data acquisition modules, wherein the GNSS receiver, the time synchronization controller and the data acquisition modules are sequentially connected;
the GNSS receiver is used for acquiring a GPS signal and transmitting the GPS signal and a GPS second pulse signal to the time synchronization controller;
the time synchronization controller is used for synchronizing the GPS time contained in the GPS signal to the system time of the data acquisition time synchronization system by taking the GPS pulse per second signal as a time synchronization reference when the GPS signal and the GPS pulse per second signal transmitted by the GNSS receiver are received;
the time synchronization controller is further used for generating an internal pulse-per-second signal when the GPS signal and the GPS pulse-per-second signal transmitted by the GNSS receiver are not received, and updating preset initial time by taking the internal pulse-per-second signal as a reference so as to obtain the system time of the data acquisition time synchronization system;
the time synchronization controller is also used for controlling the data acquisition time synchronization of the data acquisition modules according to the system time to obtain the synchronous navigation data.
2. The data acquisition time synchronization system of claim 1, wherein the data acquisition module comprises an inertial measurement unit, the synchronized navigation data comprises an attitude data frame, the inertial measurement unit is electrically connected with the time synchronization controller;
the inertial measurement unit is used for acquiring attitude information;
the time synchronization controller is used for acquiring the attitude information when detecting the effective edge of the attitude information synchronization signal transmitted by the inertial measurement unit;
the time synchronization controller is further used for recording a first sampling time and a second sampling time, wherein the first sampling time is the time when sampling starts, and the second sampling time is the time when sampling ends;
and the time synchronization controller is further used for packing the attitude information, the first sampling time and the second sampling time to obtain the attitude data frame.
3. The data acquisition time synchronization system of claim 1, wherein the data acquisition module comprises a camera device, the synchronized navigation data comprises frames of image data, the camera device is electrically connected to the time synchronization controller;
the time synchronization controller is used for generating a photographing trigger pulse by taking a preset minimum photographing time gap as a period so as to control the photographing equipment to photograph;
the time synchronization controller is further configured to record a third sampling time and a sequence number of the photographing trigger pulse, where the third sampling time is a time for sending the photographing trigger pulse;
and the time synchronization controller is also used for packing the third sampling time and the sequence number to obtain the image data frame.
4. The data acquisition time synchronization system of claim 1, wherein the data acquisition module comprises an encoder, the synchronized navigation data comprises encoder data frames, the encoder is electrically connected to the time synchronization controller;
the time synchronization controller is used for acquiring phase pulse signals of the encoder according to a preset time period and counting the phase pulse signals in each time period to obtain the pulse number;
the time synchronization controller is further configured to record a fourth sampling time and a fifth sampling time, and pack the fourth sampling time, the fifth sampling time, and the pulse number to obtain the encoder data frame, where the fourth sampling time and the fifth sampling time are a start time and an end time of one time period, respectively.
5. The system according to any one of claims 1 to 4, wherein the time synchronization controller is configured to count the received GPS second pulse signal to obtain a count value when receiving the GPS signal and the GPS second pulse signal transmitted by the GNSS receiver;
and the time synchronization controller is further used for updating the system time of the data acquisition time synchronization system to the GPS time contained in the GPS signal and clearing the count value when the count value is a first threshold value.
6. A data acquisition time synchronization method is characterized in that the method is applied to a time synchronization controller of a data acquisition time synchronization system, the data acquisition time synchronization system further comprises a GNSS receiver and a plurality of data acquisition modules, the GNSS receiver, the time synchronization controller and the plurality of data acquisition modules are sequentially connected, and the method comprises the following steps:
when a GPS signal and a GPS pulse per second signal transmitted by the GNSS receiver are received, the GPS pulse per second signal is used as a time synchronization reference to synchronize the GPS time contained in the GPS signal to the system time of the data acquisition time synchronization system;
when the GPS signal and the GPS pulse per second signal transmitted by the GNSS receiver are not received, generating an internal pulse per second signal, and updating preset initial time by taking the internal pulse per second signal as a reference so as to obtain the system time of the data acquisition time synchronization system;
and controlling the data acquisition time synchronization of the data acquisition modules according to the system time to obtain synchronous navigation data.
7. The data acquisition time synchronization method according to claim 6, wherein the data acquisition modules include an inertial measurement unit, the synchronized navigation data includes an attitude data frame, the data acquisition time synchronization for controlling the plurality of data acquisition modules according to the system time, and the step of obtaining the synchronized navigation data includes:
acquiring attitude information when detecting an effective edge of an attitude information synchronization signal transmitted by the inertial measurement unit;
recording a first sampling time and a second sampling time, wherein the first sampling time is the time when sampling starts, and the second sampling time is the time when sampling ends;
and packaging the attitude information, the first sampling time and the second sampling time to obtain an attitude data frame.
8. The data acquisition time synchronization method according to claim 6, wherein the data acquisition modules include a camera device, the synchronized navigation data includes image data frames, the data acquisition time synchronization of the plurality of data acquisition modules is controlled according to the system time, and the step of obtaining the synchronized navigation data includes:
generating a photographing trigger pulse by taking a preset minimum photographing time gap as a period so as to control the photographing equipment to photograph;
recording third sampling time and the serial number of the photographing trigger pulse, wherein the third sampling time is the time for sending the photographing trigger pulse;
and packaging the third sampling time and the sequence number to obtain an image data frame.
9. The data acquisition time synchronization method according to claim 6, wherein the data acquisition modules include encoders, the synchronized navigation data includes encoder data frames, the step of controlling data acquisition time synchronization of the plurality of data acquisition modules according to the system time, and the step of obtaining the synchronized navigation data includes:
acquiring phase pulse signals of an encoder according to a preset time period, and counting the phase pulse signals in each time period to obtain the number of pulses;
and recording a fourth sampling time and a fifth sampling time, and packaging the fourth sampling time, the fifth sampling time and the pulse number to obtain an encoder data frame, wherein the fourth sampling time and the fifth sampling time are respectively a start time and an end time of a time period.
10. The data acquisition time synchronization method according to any one of claims 6 to 9, wherein the step of synchronizing the GPS time contained in the GPS signal to the system time of the data acquisition time synchronization system with the GPS sec pulse signal as a time synchronization reference comprises:
counting the received GPS second pulse signal to obtain a count value;
when the counting value is a first threshold value, updating the system time of the data acquisition time synchronization system to the GPS time contained in the GPS signal;
and clearing the count value.
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