A multi-modal data transmission system and method for a pantograph monitoring system

Abstract

This invention discloses a multimodal data transmission system and method for a pantograph monitoring system, including a roof-mounted detection module, a transmission link, and an in-vehicle host computer. The roof-mounted detection module integrates a one-dimensional signal detection unit, a two-dimensional signal detection unit, a main control unit, and a buffer unit. The one-dimensional and two-dimensional signal detection units are respectively connected to the data input terminal of the main control unit through signal interfaces. The buffer unit is integrated with or electrically connected to the main control unit. The data output terminal of the main control unit is connected to the roof of the transmission link through a high-speed serial interface. The in-vehicle end of the transmission link is connected to the in-vehicle host computer. The in-vehicle host computer periodically sends a synchronization trigger signal through the transmission link to trigger the data packaging and uploading of the roof-mounted detection module. Time reconstruction and multimodal data alignment are performed based on the returned data. This invention improves the alignment accuracy of one-dimensional waveforms and two-dimensional images on the time axis from milliseconds to microseconds, ensuring the absolute accuracy of arcing event location.

Description

Technical Field

[0001] This invention relates to the field of rail transit monitoring and communication technology, and more specifically, to a multi-mode data transmission system and method for a pantograph monitoring system. Background Technology

[0002] Existing subway pantograph arc monitoring systems typically integrate visible light cameras, infrared thermal imagers, and ultraviolet sensors for multi-dimensional analysis of arc characteristics. However, due to the fundamental differences in sampling frequency and data format between the ultraviolet detector (outputting a high-frequency one-dimensional signal) and the camera (outputting a two-dimensional image signal), and the existence of tens of milliseconds of random network jitter and protocol stack latency in traditional Ethernet or serial buses, it is difficult to accurately align heterogeneous data on the timeline. Furthermore, the harsh electromagnetic environment of the pantograph mounted on the roof prevents the introduction of complex external synchronization clock lines, and the existing NTP network timing accuracy is only at the millisecond level, which is insufficient to meet the microsecond-level positioning synchronization requirements of arc events.

[0003] On the other hand, in existing solutions, each sensor typically uses an independent, separate channel to transmit data, lacking a unified time reference. It simply relies on the "reception time" recorded by the main control module as a timestamp, which cannot reflect the true physical acquisition time and is prone to data misalignment. At the same time, the independent cable routing method makes the wiring between the roof-mounted detection module and the in-vehicle main unit complex, which not only increases the difficulty of system integration and maintenance costs, but also makes it difficult to meet the requirements of rail transit for lightweight and high-reliability equipment installation.

[0004] Therefore, a multi-mode data transmission system and method for pantograph monitoring systems are needed to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide a multi-mode data transmission system and method for pantograph monitoring systems, overcoming the aforementioned deficiencies in the prior art.

[0006] The technical solution to achieve the objective of this invention is: a multi-mode data transmission system for a pantograph monitoring system, comprising:

[0007] Roof detection module, transmission link, and in-vehicle host computer;

[0008] The roof detection module integrates a one-dimensional signal detection unit, a two-dimensional signal detection unit, a main control unit, and a buffer unit; the one-dimensional signal detection unit and the two-dimensional signal detection unit are respectively connected to the data input terminal of the main control unit through signal interfaces; the buffer unit is integrated with or electrically connected to the main control unit.

[0009] The data output terminal of the main control unit is connected to the top of the vehicle via a high-speed serial interface; the in-vehicle end of the transmission link is connected to the in-vehicle host computer.

[0010] The in-vehicle host computer periodically sends a synchronization trigger signal through the transmission link to trigger the data packaging and uploading of the roof detection module; and performs time reconstruction and multimodal data alignment based on the returned data.

[0011] Furthermore, the one-dimensional signal detection unit includes an ultraviolet photomultiplier tube and an ultraviolet sensor;

[0012] The ultraviolet photomultiplier tube is electrically connected to the main control unit and is configured to generate a corresponding digital pulse signal when ultraviolet photons are detected, and output the digital pulse signal to the main control unit.

[0013] The ultraviolet sensor is electrically connected to the main control unit; the ultraviolet sensor has a built-in analog-to-digital converter for continuously acquiring analog ultraviolet radiation intensity and transmitting the digitized ultraviolet intensity data to the main control unit.

[0014] Furthermore, the two-dimensional signal detection unit includes a visible light camera and an infrared camera, both of which are electrically connected to the main control unit.

[0015] Furthermore, the transmission link includes a serializer and a deserializer, which are connected via a coaxial cable;

[0016] The input terminal of the serializer is connected to the main control unit and is used to receive the image signal output by the main control unit and convert the image data into a high-speed serial signal.

[0017] The deserializer is installed on the in-vehicle host computer, receives the high-speed serial signal transmitted through the coaxial cable, restores the image data, and outputs it to the in-vehicle host computer.

[0018] Furthermore, the transmission link is a GMSL transmission link, the serializer has a built-in GMSL serializer chip, and the deserializer has a built-in GMSL deserializer chip.

[0019] Furthermore, the GMSL physical layer in the GMSL transmission link has a deterministic delay, and the end-to-end transmission delay introduced by the serializer, coaxial cable and deserializer in its transmission path is a fixed value.

[0020] A multi-mode data transmission method for a pantograph monitoring system includes:

[0021] S1, the main control unit operates at a first fixed frequency. The analog-to-digital converter sample value of the ultraviolet sensor is read to obtain continuous ultraviolet intensity waveform data, while the ultraviolet pulse counting signal output by the ultraviolet photomultiplier tube is continuously counted; and written to the buffer unit in real time to form a one-dimensional waveform raw data stream to be processed.

[0022] S2, the in-vehicle host computer transmits via the GMSL link at a second fixed frequency. The system sends a hardware synchronization pulse to the main control unit; upon receiving the pulse, the main control unit starts a timer for active delay. Wait for the two-dimensional signal detection unit to complete the acquisition of the current frame, and then extract the raw one-dimensional waveform data stream accumulated since the previous synchronization moment from the buffer unit;

[0023] S3, the main control unit maps the one-dimensional waveform raw data stream extracted in S2 into image rows according to time segments, encapsulates it into standard YUV or RAW format, and embeds a timestamp representing the sampling time at the beginning of the frame to form a pseudo image frame compatible with the image transmission protocol.

[0024] S4 sends the pseudo-image frame to the serializer in the GMSL transmission link, and then transmits it to the vehicle deserializer via high-speed serial mode through the coaxial cable.

[0025] S5, the in-vehicle host computer extracts waveforms and timestamps from the received pseudo-image frames, and combines them with the link delay of the total fixed delay to reconstruct the precise acquisition time of each ultraviolet sampling point, thereby achieving time alignment between ultraviolet data and multi-modal signals such as infrared / visible light.

[0026] Furthermore, in step S2, the two-dimensional signal detection unit operates at a second fixed frequency. Transmit image data to the main control unit.

[0027] Furthermore, the precise sampling time for reconstructing each sampling point in step S5 is as follows: , in, The actual physical acquisition time of the reconstructed ultraviolet sampling point; The moment when the in-vehicle host computer sends the acquisition trigger pulse; This represents the total fixed delay of the system. The sample point count value is embedded in the first line of the pseudo-image frame. This is the first fixed frequency, i.e., the sampling rate of the ultraviolet sensor; The sampling interval is denoted as .

[0028] by Based on this, the formula reflects the separation between continuous sampling by the ultraviolet sensor and the fixed delay of the system: Only depends on The timestamp offset and sampling interval are unaffected by main control processing and transmission delays; Used to trace back from the receiving time to the sampling time.

[0029] Furthermore, the aforementioned for: , in, This refers to the time it takes for the trigger signal to be transmitted to the main control unit via the GMSL transmission link; After the main control unit receives the signal, it actively delays the time for the two-dimensional signal detection unit to complete the acquisition of the current frame. This refers to the time it takes for the main control unit to extract data from the cache unit and encapsulate it into pseudo-image frames. This refers to the time it takes for the encapsulated data to be transmitted back to the in-vehicle host computer via the GMSL transmission link.

[0030] Total fixed delay of the system Each component is pre-calibrated during system installation and debugging using an oscilloscope or code injection, and substituted into the above formula for backtracking the sampling time. This delay does not participate in the sampling process; it is only used by the host computer to deduce the actual sampling time based on the receiving time.

[0031] By adopting the above technical solution, the present invention has the following beneficial effects:

[0032] (1) This invention addresses the problem of inconsistent sampling frequencies and large format differences between the ultraviolet detector and the camera. Through a collaborative mechanism of "hardware pulse triggering + fixed-interval sampling + pseudo-image frame encapsulation," this invention eliminates the impact of tens of milliseconds of random jitter in traditional Ethernet or serial buses, as well as the fixed processing delay within the system, on time synchronization. Combined with the physical layer deterministic delay compensation formula, the alignment accuracy of the one-dimensional waveform and the two-dimensional image on the time axis is improved from milliseconds to microseconds, ensuring the absolute accuracy of arcing event localization.

[0033] (2) This invention fully utilizes the transmission characteristics of the GMSL physical layer, with a single-trip delay on the order of microseconds and a fixed and measurable delay. Compared with networked transmissions that have protocol stack overhead and queuing delays, this invention can eliminate the impact of network jitter on synchronization without complex QoS configuration, and the end-to-end delay jitter can be controlled within ±50us, ensuring the real-time performance of the monitoring data.

[0034] (3) This invention breaks through the traditional mode of independent wiring of sensors and uses a single coaxial cable to realize bidirectional high-speed transmission of downlink trigger pulses and uplink multimodal data. The "one cable for multiple uses" structure not only greatly reduces the wiring complexity and maintenance cost of the pantograph area on the roof of the subway car, but also meets the stringent requirements of rail transit for lightweight and highly integrated monitoring equipment.

[0035] (4) The system of this invention eliminates the dependence on external complex synchronization clock lines, GPS / BeiDou signals or NTP servers, and uses coaxial cables with strong anti-interference capabilities for GMSL transmission. Combined with an industrial-grade wide-temperature main control unit, it effectively solves the impact of strong electromagnetic interference such as pantograph arcing and traction motor on synchronization accuracy, ensuring that the system can still operate stably under harsh working conditions.

[0036] (5) By embedding one-dimensional waveform data row by row into standard YUV or RAW image formats, this invention cleverly reuses the existing MIPI-CSI video channel. The solution of this invention only requires about 3% bandwidth increment to achieve transparent transmission of ultraviolet data. The host computer does not need additional hardware interfaces or acquisition cards. Synchronization data can be extracted simply by parsing the "pseudo-image frames" through software, which significantly reduces the overall threshold of system modification.

[0037] (6) The synchronous transmission logic proposed in this invention has strong decoupling capabilities, and the sampling frequency, trigger frequency, and encapsulation format can be flexibly reconfigured according to monitoring requirements. In addition to arc monitoring, its core concept can be quickly applied to various rail transit application scenarios that require high-precision fusion of multi-source heterogeneous data, such as wheel-rail vibration monitoring and pantograph-catenary contact force detection. Attached Figure Description

[0038] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0039] Figure 1 This is a system architecture diagram of the present invention.

[0040] Figure 2 This is a diagram of the pseudo-image frame encapsulation format of the present invention.

[0041] Figure 3 This is a schematic diagram illustrating the time axis alignment, data acquisition, and delay compensation of the present invention.

[0042] 1. Roof detection module; 1-1. One-dimensional signal detection unit; 1-2. Two-dimensional signal detection unit; 1-3. Main control unit; 1-4. Buffer unit; 2. Transmission link; 3. In-vehicle host computer. Detailed Implementation

[0043] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0044] Example 1, such as Figure 1 As shown in the figure, this embodiment discloses a multimodal data transmission system for a pantograph monitoring system, which is used to achieve high-precision, multi-dimensional perception and synchronous transmission of the pantograph's operating status.

[0045] The system includes a roof-mounted detection module 1, a transmission link 2, and an in-vehicle host computer 3. The roof-mounted detection module 1 is installed on the roof of an electric locomotive or EMU, near the pantograph head area, and features weather resistance, electromagnetic interference resistance, and shockproof design. Internally, it integrates a one-dimensional signal detection unit 1-1, a two-dimensional signal detection unit 1-2, a main control unit 1-3, and a buffer unit 1-4. The one-dimensional signal detection unit 1-1 and the two-dimensional signal detection unit 1-2 are connected to the data input terminal of the main control unit 1-3 via dedicated signal interfaces. The buffer unit 1-4 is integrated with the main control unit 1-3 on a circuit board and interconnected via a high-speed parallel bus for temporary storage of raw detection data.

[0046] The one-dimensional signal detection unit 1-1 includes an ultraviolet photomultiplier tube and an ultraviolet sensor. The ultraviolet photomultiplier tube is sensitive to ultraviolet photons generated by the pantograph discharge. When a single photon is detected, it outputs a standard TTL level pulse signal, which is directly sent to the high-speed counting pin of the main control unit 1-3 through the GPIO interface. The ultraviolet sensor has a built-in analog-to-digital converter (ADC) that continuously acquires the analog signal of ultraviolet radiation intensity at a fixed sampling rate and transmits the digitized intensity data to the main control unit 1-3 in real time through the SPI interface.

[0047] The two-dimensional signal detection unit 1-2 includes a global shutter visible light camera and an uncooled infrared thermal imaging camera. Both cameras are connected to the main control unit 1-3 via a MIPI CSI interface and support external hardware-triggered synchronization.

[0048] The main control units 1-3 are used to coordinate the data acquisition, buffer management, timestamp embedding, and data encapsulation of various sensors. Their data output terminals are connected to the vehicle-mounted serializer on transmission link 2 via the MIPI CSI interface.

[0049] Transmission link 2 consists of a GMSL serializer, a coaxial cable, and a GMSL deserializer. The serializer uses a GMSL serializer chip, integrated inside the roof-mounted detection module, to receive MIPI image data streams from main control units 1-3 and convert them into high-speed serial signals. The deserializer uses a GMSL deserializer chip and is installed on the acquisition board of the in-vehicle host computer 3. The two are connected by a coaxial cable, supporting bidirectional communication and power supply. The GMSL physical layer in the GMSL transmission link has a deterministic delay; the end-to-end transmission delay introduced by the serializer, coaxial cable, and deserializer in its transmission path is a fixed value.

[0050] See Figure 2 and Figure 3 A multi-modal data transmission method for a pantograph monitoring system based on the above system includes:

[0051] S1, the main control unit 1-3 reads the sampled value of the analog-to-digital converter of the ultraviolet sensor at a first fixed frequency of 10kHz to obtain continuous ultraviolet intensity waveform data, and at the same time continuously counts the ultraviolet pulse counting signal output by the ultraviolet photomultiplier tube; and writes it into the buffer unit 1-4 in real time to form a one-dimensional waveform raw data stream to be processed;

[0052] S2, the in-vehicle host computer 3 sends a hardware synchronization pulse to the main control unit 1-3 at a second fixed frequency of 60Hz via the GMSL transmission link; after receiving the trigger signal, the main control unit 1-3 immediately sends a hardware exposure signal to the two-dimensional signal detection unit 1-2, and the infrared camera and visible light camera then begin to acquire the current frame (exposure + readout, total time <1ms). At the same time, the main control unit starts a 1ms timer, which is used to wait for the two-dimensional signal detection unit to complete the acquisition, ensuring that the image frame is ready when the data is packaged, and that the ultraviolet data packet completely covers the acquisition window; after the delay, the main control unit extracts the accumulated one-dimensional waveform raw data stream from the buffer unit 1-4 since the previous synchronization moment;

[0053] S3, the main control unit 1-3 maps the one-dimensional waveform raw data stream extracted in S2 into image rows according to time segments, encapsulates it into standard YUV or RAW format, and embeds a timestamp representing the sampling time at the beginning of the frame to form a pseudo image frame compatible with the image transmission protocol; the two-dimensional signal detection unit 1-2 transmits image data to the main control unit 1-3 at the same second fixed frequency of 60Hz.

[0054] Ten sampling points (10kHz sampling rate) every 1ms are grouped into one line of data; each frame (corresponding to one trigger cycle, approximately 16.67ms) contains 17 lines of waveform data; simultaneously, a timestamp counter is embedded in the first line of each frame to record the sampling time of that frame's data relative to the trigger signal (in units of sampling points, with an accuracy of 100µs). The image encapsulation format is as follows: Figure 2 As shown.

[0055] S4 sends the pseudo-image frame to the serializer in the GMSL transmission link, and then transmits it to the vehicle deserializer via high-speed serial mode through the coaxial cable.

[0056] S5, the in-vehicle host computer 3 extracts the waveform and timestamp from the received pseudo image frame, and combines the link delay of the total fixed delay to reconstruct the precise acquisition time of each ultraviolet sampling point, so as to realize the time alignment of ultraviolet data with multimodal signals such as infrared / visible light.

[0057] The precise sampling time for reconstructing each ultraviolet sampling point is as follows: , in, The actual physical acquisition time of the reconstructed ultraviolet sampling point; The moment when the in-vehicle host computer sends the acquisition trigger pulse; This represents the total fixed delay of the system. The sample point count value is embedded in the first line of the pseudo-image frame. This is the first fixed frequency, i.e., the sampling rate of the ultraviolet sensor; The sampling interval is specified. In this embodiment, ,Right now . Given, by The base value is 0, and it can be positive or negative.

[0058] The for: ,

[0059] in, The time it takes for the trigger signal to be transmitted to the main control unit 1-3 via the GMSL transmission link; After receiving the signal, the main control unit 1-3 actively delays the time for the two-dimensional signal detection unit 1-2 to complete the acquisition of the current frame. The time it takes for the main control unit 1-3 to extract data from the cache unit 1-4 and encapsulate it into pseudo-image frames; The time it takes for the encapsulated data to be transmitted back to the in-vehicle host computer 3 via the GMSL transmission link.

[0060] The specific methods for reconstructing the precise acquisition time of each ultraviolet sampling point, time axis alignment, and delay compensation are as follows:

[0061] The latency effects to be eliminated by this system mainly include: downlink trigger transmission latency, master control active latency, data processing encapsulation latency, and uplink transmission latency. The sum of these latency effects constitutes the total fixed latency. .

[0062] Because the ultraviolet sensor operates at a fixed frequency Continuous sampling is performed, and each sampling point has a timestamp count value n relative to the trigger time of the host computer (n is 0 based on the trigger time, negative before trigger, and positive after trigger). However, there is a total fixed delay between the actual time the host computer receives the data packet and the sampling point's acquisition time. To eliminate the impact of this delay, the host computer uses the following compensation method to reconstruct the actual acquisition time of each sampling point:

[0063] Step 1: Pre-calibrate the fixed delay

[0064] Downlink Triggered Transmission Delay During the system installation and debugging phase, use an oscilloscope to simultaneously measure the trigger signal output pin of the host computer and the main control receiving pin on the roof. Measure the time difference between the rising edges of the two signals. This delay is a fixed value, and the actual value depends on the selected GMSL chip model and configuration. It is usually in the microsecond range (such as 3us~10us for GMSL2 chips). It can be measured and calibrated by an oscilloscope during system installation and debugging.

[0065] Main controller active delay The software is set to 1ms.

[0066] Data processing encapsulation latency Measurements were taken via code injection (timestamps were recorded at the entry and exit points of the master control data package), with a typical value of 200µs.

[0067] Uplink transmission delay This refers to the total time required for the encapsulated pseudo-image frame to be sent from the roof-mounted main control unit, transmitted via the GMSL link, and fully received by the in-vehicle host computer. This delay is a fixed value, and its magnitude depends on the data packet length, GMSL chip model, and configuration. It typically ranges from tens to hundreds of microseconds; in this embodiment, the measured delay is approximately 150 µs. This delay is not necessarily equal to the downlink trigger delay in value, but both are fixed values, calibrated and then input into the total fixed delay formula. Note: The "total time" here includes the entire process of data serialization, cable propagation, deserialization recovery, and the host computer reading the data into memory to ensure the accuracy of the backsampling time.

[0068] Calculate the total fixed delay: .

[0069] Step 2: Reverse compensation after receiving data packets

[0070] The host computer extracts the timestamp count value n from the pseudo-image frame, and uses the locally recorded trigger sending time T_host computer sending time and the pre-calibrated total fixed delay to reconstruct the actual acquisition time of each sampling point according to the following formula: ,

[0071] The physical meaning of this formula is: Sampling point acquisition time = Host computer trigger transmission time - System fixed delay + Timestamp offset. Since all delays are fixed values, the compensation obtained... This is the actual physical sampling time of the ultraviolet sensor.

[0072] Step 3: Time alignment with the 2D image

[0073] The exposure start time of the infrared / visible light camera is (The camera is triggered immediately after the main controller receives the trigger). The total time for camera acquisition (exposure + readout) is less than [amount missing]. (1ms). The host computer aligns the ultraviolet waveform data and the image frame along the same time axis based on the actual acquisition time of the reconstructed ultraviolet sampling points and the camera exposure start time (known). Since the ultraviolet data packet covers the entire camera acquisition window (from before the trigger to 1ms after the trigger), the aligned one-dimensional waveform and the two-dimensional image correspond precisely in time.

[0074] Step 4: Validation of Results

[0075] Using the above compensation method, the end-to-end alignment error of the system is mainly determined by the clock crystal drift. When using a temperature-compensated crystal (frequency deviation ≤ ±50ppm), the maximum drift is ±0.8us within a 60Hz trigger period (16.67ms), achieving microsecond-level time synchronization and fully meeting the positioning requirements of arc detection for high-speed transient signals.

[0076] In this embodiment, see Figure 3 The system's data acquisition process, time axis alignment process, and fixed delay compensation process are also shown.

[0077] The in-vehicle host computer sends hardware synchronization trigger pulses at a fixed 60Hz cycle. The trigger signal is transmitted to the roof-mounted main control unit via the GMSL link. Upon receiving the trigger signal, the main control unit immediately sends exposure trigger signals to the infrared and visible light cameras, causing the two-dimensional signal detection unit to begin acquiring the current frame image.

[0078] Since the two-dimensional signal detection unit needs a certain amount of time to complete the exposure and readout of one frame of image, the main control unit initiates a preset delay. In this embodiment, the delay time is 1ms, which is used to ensure that the image data arrives completely in the buffer area. After the delay ends, the main control unit extracts the one-dimensional ultraviolet waveform data accumulated since the previous synchronization cycle from the buffer unit and completes data encapsulation and pseudo-image frame generation.

[0079] The encapsulated data is transmitted back to the in-vehicle host computer via the GMSL link. After receiving the complete data packet, the host computer performs time reconstruction for each ultraviolet sampling point based on the pre-calibrated total fixed system delay and the timestamp count carried in the pseudo-image frame.

[0080] Figure 3 The mid-ultraviolet sensor continuously samples at fixed intervals of 100µs. The count value of each sampling point is zeroed out at the trigger reference point, where the count value of sampling points is negative before triggering and positive after triggering. By compensating for the timestamp count value with a fixed delay, the actual physical acquisition time corresponding to each sampling point can be obtained, and a unified timeline can be established with the infrared and visible light images to achieve microsecond-level synchronization and alignment of multimodal data.

[0081] The total fixed system delay consists of downlink transmission time, master control active delay time, data processing and encapsulation time, and uplink transmission time. Each of these delays is a fixed value pre-calibrated during the system installation and commissioning phase to eliminate time deviations introduced by the transmission link and processing flow.

[0082] This embodiment addresses the issues of inconsistent sampling frequencies and significant format differences between the ultraviolet detector and the camera. The invention employs a collaborative mechanism of "hardware pulse triggering + fixed-interval sampling + pseudo-image frame encapsulation" to eliminate the tens of milliseconds of random jitter present in traditional Ethernet or serial buses. Combined with a physical layer deterministic delay compensation formula, the alignment accuracy of the one-dimensional waveform and the two-dimensional image on the time axis is improved from milliseconds to microseconds, ensuring absolute accuracy in locating arcing events.

[0083] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-mode data transmission system for a pantograph monitoring system, characterized in that, include: Roof detection module (1), transmission link (2) and in-vehicle host computer (3); The roof detection module (1) integrates a one-dimensional signal detection unit (1-1), a two-dimensional signal detection unit (1-2), a main control unit (1-3), and a buffer unit (1-4); the one-dimensional signal detection unit (1-1) and the two-dimensional signal detection unit (1-2) are respectively connected to the data input terminal of the main control unit (1-3) through signal interfaces; the buffer unit (1-4) is integrated with or electrically connected to the main control unit (1-3); The data output terminal of the main control unit (1-3) is connected to the top of the vehicle via a high-speed serial interface; the in-vehicle end of the transmission link (2) is connected to the in-vehicle host computer (3). The in-vehicle host computer (3) periodically sends a synchronization trigger signal through the transmission link (2) to trigger the data packaging and uploading of the roof detection module (1); and performs time reconstruction and multimodal data alignment based on the returned data.

2. The multi-mode data transmission system for a pantograph monitoring system according to claim 1, characterized in that, The one-dimensional signal detection unit (1-1) includes an ultraviolet photomultiplier tube and an ultraviolet sensor; The ultraviolet photomultiplier tube is electrically connected to the main control unit (1-3) and is configured to generate a corresponding digital pulse signal when ultraviolet photons are detected, and output the digital pulse signal to the main control unit (1-3). The ultraviolet sensor is electrically connected to the main control unit (1-3); the ultraviolet sensor has a built-in analog-to-digital converter for continuously acquiring analog ultraviolet radiation intensity and transmitting the digitized ultraviolet intensity data to the main control unit (1-3).

3. The multi-mode data transmission system for a pantograph monitoring system according to claim 1, characterized in that, The two-dimensional signal detection unit (1-2) includes a visible light camera and an infrared camera, both of which are electrically connected to the main control unit (1-3).

4. The multi-mode data transmission system for a pantograph monitoring system according to claim 1, characterized in that, The transmission link (2) includes a serializer and a deserializer, which are connected by a coaxial cable; The input terminal of the serializer is connected to the main control unit (1-3) and is used to receive the image signal output by the main control unit (1-3) and convert the image data into a high-speed serial signal; The deserializer is installed on the in-vehicle host computer (3), receives the high-speed serial signal transmitted through the coaxial cable, restores the image data, and outputs it to the in-vehicle host computer (3).

5. The multi-mode data transmission system for a pantograph monitoring system according to claim 4, characterized in that, The transmission link (2) is a GMSL transmission link, the serializer has a built-in GMSL serializer chip, and the deserializer has a built-in GMSL deserializer chip.

6. The multi-mode data transmission system for a pantograph monitoring system according to claim 5, characterized in that, The GMSL physical layer in the GMSL transmission link has a deterministic delay, and the end-to-end transmission delay introduced by the serializer, coaxial cable and deserializer in its transmission path is a fixed value.

7. A multi-mode data transmission method for a pantograph monitoring system, characterized in that, include: S1, the main control unit (1-3) operates at a first fixed frequency. The analog-to-digital converter sampling value of the ultraviolet sensor is read to obtain continuous ultraviolet intensity waveform data, while the ultraviolet pulse counting signal output by the ultraviolet photomultiplier tube is continuously counted; and written to the buffer unit (1-4) in real time to form a one-dimensional waveform raw data stream to be processed. S2, the in-vehicle host computer (3) transmits via the GMSL link at a second fixed frequency Send a hardware synchronization pulse to the main control unit (1-3); upon receiving the pulse, the main control unit (1-3) starts a timer for active delay. Wait for the two-dimensional signal detection unit (1-2) to complete the acquisition of the current frame, and then extract the original one-dimensional waveform data stream accumulated since the previous synchronization moment from the buffer unit (1-4); S3, the main control unit (1-3) maps the one-dimensional waveform raw data stream extracted in S2 into image rows according to time segments, encapsulates it into standard YUV or RAW format, and embeds a timestamp representing the sampling time at the beginning of the frame to form a pseudo image frame compatible with the image transmission protocol. S4 sends the pseudo-image frame to the serializer in the GMSL transmission link, and then transmits it to the vehicle deserializer via high-speed serial mode through the coaxial cable. S5, the in-vehicle host computer (3) extracts the waveform and timestamp from the received pseudo image frame, and reconstructs the precise acquisition time of each ultraviolet sampling point by combining the link delay of the total fixed delay, so as to realize the time alignment of ultraviolet data with multimodal signals such as infrared / visible light.

8. A multi-mode data transmission method for a pantograph monitoring system according to claim 7, characterized in that, In step S2, the two-dimensional signal detection unit (1-2) operates at a second fixed frequency. Transmit image data to the main control unit (1-3).

9. A multi-mode data transmission method for a pantograph monitoring system according to claim 8, characterized in that, The precise sampling time for reconstructing each UV sampling point in step S5 is as follows: ， in, The actual physical acquisition time of the reconstructed ultraviolet sampling point; The moment when the in-vehicle host computer sends the acquisition trigger pulse; This represents the total fixed delay of the system. The sample point count value is embedded in the first line of the pseudo-image frame. This is the first fixed frequency, i.e., the sampling rate of the ultraviolet sensor; The sampling interval is denoted as .

10. A multi-mode data transmission method for a pantograph monitoring system according to claim 9, characterized in that, The for: ， in, The time it takes for the trigger signal to be transmitted to the main control unit (1-3) via the GMSL transmission link; After the main control unit (1-3) receives the signal, it actively delays the time for the two-dimensional signal detection unit (1-2) to complete the acquisition of the current frame. The time it takes for the main control unit (1-3) to extract data from the cache unit (1-4) and encapsulate it into a pseudo image frame; The time it takes for the encapsulated data to be transmitted back to the in-vehicle host computer (3) via the GMSL transmission link.

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