Sand application control method, system and locomotive

Abstract

This application provides a sand-spreading control method, system, and locomotive. The sand-spreading control method includes: determining the rail surface category of the rail to be contacted based on an image frame sequence acquired by the environmental sensing unit of the sand-spreading device from the rail surface of the wheel-rail to be contacted in the locomotive's forward direction; the rail surface category includes at least one of dry, slightly wet, waterlogged, icy, and oily; and determining the sand-spreading mode of the sand-spreading device on the rail surface of the rail to be contacted based on the rail surface category. Because the sand-spreading mode is determined based on the rail surface category of the rail to be contacted in the locomotive's forward direction, compared to related technologies that can only initiate sand-spreading based on locomotive wheel slippage data, this application's sand-spreading control method is a feedforward control method. It can determine the sand-spreading mode on the wheel surface before the wheel-rail contacts the wheel surface and perform sand-spreading accordingly. This means that the sand-spreading control method is more closely aligned with the actual needs of the wheel surface, reducing wasted sand-spreading and lowering the probability of accidents.

Description

Technical Field

[0001] This application relates to the field of rail transit equipment and intelligent control technology, and in particular to sand spreading control methods, systems and electronic devices. Background Technology

[0002] In modern rail transit systems, the traction and braking performance of locomotives and rolling stock directly affects operational safety, efficiency, and infrastructure lifespan. Wheel-rail adhesion is a core physical factor influencing these performance characteristics. Sanding systems, as a key auxiliary means to improve wheel-rail adhesion, have been widely applied in various rail transit equipment, including electric locomotives, diesel locomotives, and multiple units (MMUs).

[0003] Current sand-spreading systems activate sand-spreading based on locomotive wheel slippage data; however, this sand-spreading control method still poses significant safety risks. Summary of the Invention

[0004] The purpose of this application is to provide a sand-spreading control method, system, and locomotive that can solve the problem that the sand-spreading control methods in related technologies still have safety hazards.

[0005] To solve the above-mentioned technical problems, the embodiments of this application are implemented through the following aspects.

[0006] In a first aspect, embodiments of this application provide a sand-spreading control method, comprising: determining the rail surface category of the rail to be contacted based on an image frame sequence acquired by the environmental sensing unit of the sand-spreading device of the rail surface of the rail to be contacted in the direction of locomotive travel; the rail surface category including at least one of dry, slightly wet, water accumulation, icing, and oil stains; and determining the sand-spreading mode of the sand-spreading device on the rail surface of the rail to be contacted based on the rail surface category of the rail to be contacted.

[0007] Secondly, embodiments of this application provide a sand-spreading system, including a sand-spreading device and a control unit. The control unit is connected to the sand-spreading device, which is installed at the bottom of a locomotive and is used to spread sand on the rail surface of the wheel rail to be contacted in the forward direction of the locomotive. The control unit is used to execute the method described in the first aspect.

[0008] Thirdly, embodiments of this application provide a locomotive that includes a sand-spreading system as described in the second aspect.

[0009] Fourthly, this application provides a sand-spreading control device, comprising: a rail surface category determination module, configured to determine the rail surface category of the rail to be contacted based on an image frame sequence acquired by the environmental sensing unit of the sand-spreading device from the rail surface of the rail to be contacted in the direction of locomotive travel, wherein the rail surface category includes at least one of dry, slightly wet, water accumulation, icing, and oil stains; and a sand-spreading mode determination module, configured to determine the sand-spreading mode of the sand-spreading device on the rail surface of the rail to be contacted based on the rail surface category of the rail to be contacted.

[0010] Fifthly, embodiments of this application provide an electronic device, including: a memory, a processor, and computer-executable instructions stored in the memory and executable on the processor, wherein the computer-executable instructions, when executed by the processor, implement the steps of the method described in the first aspect.

[0011] In a sixth aspect, embodiments of this application provide a computer-readable storage medium for storing computer-executable instructions that, when executed by a processor, implement the steps of the method described in the first aspect.

[0012] In this embodiment, based on the image frame sequence acquired by the environmental sensing unit of the sand-spreading device from the rail surface of the wheel-rail to be contacted in the direction of locomotive travel, the rail surface category of the approaching wheel-rail is determined. This rail surface category includes at least one of dry, slightly damp, waterlogged, icy, and oily conditions. Based on the rail surface category, the sand-spreading mode of the sand-spreading device is determined. Since the sand-spreading mode is determined based on the rail surface category of the wheel-rail to be contacted in the direction of locomotive travel, compared to related technologies that can only initiate sand-spreading based on locomotive wheel slippage data, the sand-spreading control method of this application is a feedforward control method. It can determine the sand-spreading mode for the wheel surface before the wheel-rail contacts the wheel surface and then perform sand-spreading. This means that the sand-spreading control method is more closely aligned with the actual needs of the wheel surface, reducing the waste of sand-spreading and lowering the probability of accidents. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This illustration shows a flowchart of a sand-spreading control method provided in an embodiment of this application; Figure 2 This illustration shows a flowchart of a sand-spreading control method provided in an embodiment of this application; Figure 3 This invention provides a schematic flowchart of a sand-spreading control device according to an embodiment of the present application. Figure 4 A schematic diagram of the hardware structure of the electronic device provided in the embodiments of this application. Detailed Implementation

[0015] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0016] Current sand-spreading systems activate sand spreading based on locomotive wheel slippage data. However, this method still poses significant safety risks. For example, in related technologies, the system only activates the pneumatic solenoid valve to push sand stored in the sand box to the track contact point via the sand delivery pipe when the driver manually triggers the sand-spreading command or the train control management system detects wheelset slippage or sliding. However, activating sand spreading only when wheelset slippage or sliding occurs means that sand spreading is initiated only after a safety hazard has been detected, still resulting in a high probability of accidents. To reduce the probability of accidents, another sand-spreading control method has been adopted: spreading a large amount of sand regardless of whether the wheels are slipping or spinning. However, this method leads to significant waste.

[0017] In order to reduce the waste of sand spreading and lower the probability of safety accidents, that is, to effectively reduce the probability of safety hazards with less sand spreading, the inventors of this application have proposed a sand spreading control method according to the embodiments of this application.

[0018] In this application embodiment, the sand conveying device or system can be a vehicle-mounted sand conveying device or system, and can be located at the front and / or rear of the locomotive, for spreading sand on the rail surface of the wheel rail to be contacted in the direction of locomotive travel, thereby realizing a feedforward sand spreading control method. In this application embodiment, the locomotive can refer to a train locomotive, that is, a type of railway equipment.

[0019] Figure 1This diagram illustrates a flow chart of a sand-spreading control method provided in an embodiment of this application. The method can be executed by a control unit or controller, or by electronic equipment, such as a terminal device or server device. In other words, the method can be executed by a controller or intelligent control unit located on a locomotive, and the method can be executed by software or hardware installed on a terminal device or server device. The server includes, but is not limited to, a single server, a server cluster, a cloud server, or a cloud server cluster. Figure 1 As shown, the method may include the following steps.

[0020] Step S102: Based on the image frame sequence acquired by the environmental sensing unit of the sand spreading device of the rail surface to be contacted in the direction of locomotive travel, determine the rail surface category of the rail surface to be contacted. The rail surface category includes at least one of dry, slightly damp, waterlogged, icy, and oily. This can be achieved by acquiring an image frame sequence of the rail surface of the rail surface to be contacted for a predetermined length in the direction of locomotive travel.

[0021] Step S104: Determine the sand-spraying mode of the sand-spraying device on the rail surface of the wheel and rail to be contacted according to the rail surface type of the wheel and rail to be contacted.

[0022] In this embodiment, the sand-spreading mode is determined by the type of rail surface to be contacted in the direction of locomotive travel. Compared with related technologies, which can only start sand spreading based on the slippage data of locomotive wheels, the sand spreading control method of this application is a feedforward control method. It can determine the sand spreading mode of the wheel surface before the rail contacts the wheel surface and spread sand. In other words, this sand spreading control method is more in line with the actual needs of the wheel surface, which reduces the waste of sand spreading and also reduces the probability of accidents.

[0023] In one embodiment, step S102 may include: determining the rail surface type of the wheel-rail to be contacted based on the image frame sequence acquired by the environmental sensing unit of the sand-spreading device of the rail surface of the locomotive in the direction of travel, and / or the wheel-rail noise pickup array acquired by the environmental sensing unit. The wheel-rail noise pickup array may be subjected to a voiceprint recognition algorithm to distinguish the acoustic characteristics of dry (high-frequency sharp friction sound), wet (low-pitched muffled sound), and oiled (attenuation in a specific frequency band) noise. This wheel-rail noise pickup array can be obtained by collecting friction noise during wheel-rail contact using directional microphones installed at the bogie.

[0024] In one possible implementation, the sand-spreading control method can be applied to the locomotive's control unit, such as an intelligent control unit.

[0025] In one possible implementation, the sand spreading device may include a sand box, a sand conveying pipe, and a nozzle that are interconnected. The sand stored in the sand box can be sprayed from the nozzle to a designated position on the track surface via the sand conveying pipe.

[0026] In the embodiments of this application, the sand spraying mode may include: continuous sand spraying, periodic intermittent sand spraying, and stopped sand spraying.

[0027] Step S104 above may include at least one of the following: when the rail surface type is icy and / or oily, determine the sand-spraying mode as continuous sandblasting; when the rail surface type is slightly wet and / or waterlogged, determine the sand-spraying mode as periodic intermittent sandblasting; when the rail surface type is dry, determine the sand-spraying mode as stopped sandblasting. Because there is a high anti-slip requirement when the rail surface type is icy and / or oily, continuous sandblasting is performed on the rail surface to be contacted to reduce the probability of safety accidents; when the rail surface type is dry, there is no anti-slip requirement, so sandblasting can be stopped to reduce the waste of sand; when the rail surface type is slightly wet and / or waterlogged, there is a certain anti-slip requirement, so periodic intermittent sandblasting can be selected to meet the anti-slip requirement while reducing the waste of sand.

[0028] In one possible implementation, when the rail surface type is dry, the corresponding sanding mode can be stopped regardless of whether a wheel slippage signal or a wheel idling signal is received. Of course, in some embodiments, when the rail surface type is dry, if a wheel slippage signal or a wheel idling signal is received, the corresponding sanding mode can be periodic intermittent sandblasting, or even short-duration continuous sandblasting.

[0029] In this embodiment, the environmental sensing unit can be located below the front end of the locomotive obstacle clearer and / or on the front side of the bogie. This environmental sensing unit may include a multispectral polarization imaging module.

[0030] In this embodiment, step S102 may include: sequentially acquiring multiple image frames of the track surface of the wheel-rail contact area to be contacted along a distance of not less than a first preset length using a multispectral polarization imaging module. The image frame sequence includes multiple image frames. That is, the multispectral polarization imaging module should be able to cover a field of view extending at least 3 meters in front of the wheel-rail contact area. The first preset length can be 3 meters, or a length beyond 3 meters, such as 2 meters or 4 meters. The value of the first preset length can be set to ensure that the sand-spreading pattern on the track surface is determined before the locomotive wheels contact the track surface. In one possible implementation, the first preset length can be fixed or adjustable according to the real-time speed of the locomotive; for example, the faster the locomotive speed, the larger the value of the first preset length.

[0031] In one possible implementation, step S102 above may include the following steps: Based on each image in the image frame sequence, determine the track surface category corresponding to that image frame; The rail surface category of the wheel and rail to be contacted is determined based on the category of all image frames on the rail surface.

[0032] For example, if in a given set of all image frames on the rail surface of the wheel to be contacted, any image frame corresponds to a rail surface category of icing and / or oil contamination, then the rail surface category of the wheel to be contacted is determined to be icing and / or oil contamination; if in a given set of all image frames on the rail surface of the wheel to be contacted, any image frame corresponds to a rail surface category of slightly damp and / or water accumulation, and all image frames do not correspond to rail surface categories of icing and / or oil contamination, then the rail surface category of the wheel to be contacted is determined to be slightly damp and / or water accumulation; if in a given set of all image frames on the rail surface of the wheel to be contacted, none of the image frames correspond to rail surface categories of icing and / or oil contamination, slightly damp and / or water accumulation, then the rail surface category of the wheel to be contacted is determined to be dry.

[0033] For example, in a certain acquisition of all image frames on the rail surface of the wheel and rail to be contacted, the proportion of image frames occupied by ice and / or oil stains, the proportion of image frames occupied by slightly wet and / or water accumulation, and the proportion of image frames occupied by dryness are determined, and the rail surface category of the image frame with the highest proportion is determined as the rail surface category of the wheel and rail to be contacted.

[0034] In one possible implementation, the multispectral polarization imager may include two CMOS image sensors sharing the same optical lens system. The two CMOS image sensors can be configured with filters for s-polarization and p-polarization directions, respectively, and the incident light is separated according to polarization state by a beam splitter before being projected onto the corresponding photosensitive chip. The operating band of this multispectral polarization imaging module can cover the visible to near-infrared region, with three center wavelengths of 550nm, 650nm, and 850nm, to enhance the ability to extract feature differences of water films, ice layers, and oil stains under different spectral responses. In another possible implementation, the environmental perception unit may include an embedded image processing board. This board uses an ARM Cortex-A72 quad-core processor with a main frequency of 1.8GHz, capable of running a lightweight convolutional neural network classification model. This model is trained offline and then stored in the onboard eMMC memory. Its input is a sequence of synchronously acquired multi-channel polarization image frames, and its output is a track surface state category label. The category set can be limited to five categories: dry, slightly wet, water accumulation, icing, and oil stains. The reasoning process of the classification model is implemented using fixed-point quantization, and the processing time for each frame of image can be no more than 33 milliseconds, which meets the real-time requirements of the locomotive running at a speed of 160km / h. The environmental perception unit can periodically send the track surface status recognition results to the intelligent control unit through the CAN FD bus interface, and the sending period can be 50ms.

[0035] In one possible implementation, the multispectral polarization imaging module in the environmental perception unit can be equipped with an active illumination source, which consists of three independently controlled LED arrays corresponding to wavelengths of 550nm, 650nm, and 850nm, respectively. Each array consists of 12 high-brightness LEDs with radiant intensities of 1200mcd, 1000mcd, and 850mW / sr, respectively, and half-intensity angles of ±30°. The active illumination source is triggered synchronously with the image sensor to ensure that high-quality polarization images can still be acquired in low-light environments such as at night or in tunnels. The driving current of the LED array is provided by a constant current source circuit with a current ripple of less than 2% to avoid interference from light intensity fluctuations in polarization calculation.

[0036] In one possible implementation, the lightweight convolutional neural network classification model can employ a depthwise separable convolutional structure, comprising 12 convolutional layers, with an input size of 224×224 pixels and an output of a 5-dimensional softmax probability distribution. The total number of model parameters is 1.2MB, and after TensorRT optimization, it can achieve an inference speed of 30 frames per second on an embedded image processing board. The training dataset contains 150,000 labeled images, covering different seasons, weather, lighting conditions, and track sections, with oil and sewage film samples accounting for no less than 30% to ensure the model's ability to distinguish key confusing categories.

[0037] Of course, in some embodiments, the multispectral polarization imaging module and lightweight convolutional neural network classification model described above may not be used to identify the type of rail surface to be contacted. Instead, other methods can be used for identification. For example, a laser reflection intensity sensor can be used to classify the different reflectivity intensities of laser light on the surfaces of different media (water, ice, oil, dry road surface); another example is to use an infrared thermal imager to distinguish between icy or waterlogged areas by using the differences in heat capacity and infrared emissivity between water, ice, and rails through temperature distribution maps; or, for example, a hyperspectral imager can be used to collect spectral information in a narrower band than multispectral imaging, and the composition of oil stains can be accurately identified through the "spectral fingerprint" of the material; or, for example, a conventional RGB camera with texture analysis can be used, using only visible light images, and relying on deep learning to extract features of water reflection and oil stain color and texture (low cost, but poor anti-interference). These methods are all non-contact optical / physical sensing technologies. Their core logic is to utilize the differences in the physical response characteristics of different coverings (water / ice / oil) to light, heat or waves, and combine them with algorithms to achieve qualitative discrimination of material categories, thereby providing feedforward input for sand-spreading decisions.

[0038] In addition, the environment perception unit can use multi-band lidar or laser reflection intensity sensors instead of multispectral polarization to emit laser beams of specific wavelengths (such as 905nm and 1550nm) towards the orbital surface and measure the echo intensity. Since water, ice, oil, and dry orbital surfaces have huge differences in the absorption and reflectivity of different wavelengths of laser light (for example, water has strong absorption at 1550nm and extremely low reflection), material classification can be achieved by combining machine learning algorithms.

[0039] In this embodiment, the sand-spreading device may further include a signal generator and a solenoid valve. The solenoid valve controls the intake of pressurized air into the sand-feeding pipe of the sand-spreading device to propel the sand towards the nozzle of the sand-spreading device. The aforementioned sand-spreading control method may further include: determining the duty cycle of the control signal output by the signal generator according to the sand-spreading mode, wherein the signal generator outputs a control signal to the solenoid valve. The signal generator may be a PWM signal generator, and correspondingly, the solenoid valve may also be a PWM solenoid valve.

[0040] The PWM solenoid valve can be a high-speed PWM solenoid valve. This high-speed PWM solenoid valve is a normally closed direct-acting type with a rated voltage of DC24V, an opening response time ≤5ms, a closing response time ≤8ms, a maximum working pressure of 600kPa, and NPT 1 / 2 threaded connections for the valve body inlet and outlet, achieving an IP66 sealing rating. This solenoid valve directly controls the entry of compressed air into the sand conveying pipeline, propelling the sand towards the nozzle.

[0041] In some embodiments, instead of using PWM solenoid valves to control sand flow, other valves can be used. For example, a screw feeder can be used, with a motor driving the screw to rotate, and the amount of sand pushed can be precisely controlled by adjusting the motor speed (mechanical metering). Another example is a piezoelectric injection valve, which uses the deformation of a piezoelectric crystal to control the opening and closing of the valve port, offering a faster response time than solenoid valves and suitable for extremely high-precision point injection. Alternatively, a proportional solenoid valve can be used, linearly adjusting the valve core opening by controlling the current magnitude, thereby continuously regulating the airflow, rather than the "all-open, all-closed" mode of PWM. Or, a rotary valve / star-shaped discharge valve can be used, controlling the amount of sand discharged by the rotational speed of the impeller, commonly used for industrial powder conveying. All these valves are variable flow control devices. Their core purpose is to change the traditional "constant opening" mode and achieve quantitative modulation of the output medium (sand / air) to adapt to different viscosity-enhancing requirements.

[0042] In continuous sandblasting mode, the duty cycle of the control signal output by the signal generator can be a 100% PWM signal, causing the solenoid valve to remain open continuously, achieving maximum flow rate continuous sandblasting. In periodic intermittent sandblasting mode, the duty cycle of the control signal output by the signal generator can be a 30% to 50% PWM signal, causing the solenoid valve to operate in a high-frequency point-and-shoot manner. For example, the duration of each opening can be 10ms to 20ms, and the interval can be 20ms to 40ms. In stop sandblasting mode, the duty cycle of the control signal output by the signal generator can be a 0% PWM signal to prohibit sand spreading.

[0043] Figure 2 This diagram illustrates another flow chart of the sand-spreading control method provided in this application. The method can be executed by a control unit or controller, or by electronic equipment, such as a terminal device or server device. In other words, the method can be executed by a controller or intelligent control unit located on a locomotive, and the method can be executed by software or hardware installed on a terminal device or server device. The server includes, but is not limited to, a single server, a server cluster, a cloud server, or a cloud server cluster. Figure 2 As shown, the method may include the following steps.

[0044] Step S202: Based on the image frame sequence acquired by the environmental sensing unit of the sand spreading device of the rail surface to be contacted in the direction of locomotive travel, determine the rail surface category of the rail surface to be contacted. The rail surface category includes at least one of dry, slightly damp, waterlogged, icy, and oily. This can be achieved by acquiring an image frame sequence of the rail surface of the rail surface to be contacted for a predetermined length in the direction of locomotive travel.

[0045] Step S204: Determine the sand-spraying mode of the sand-spraying device on the rail surface of the wheel and rail to be contacted according to the rail surface type of the wheel and rail to be contacted.

[0046] Step S206: Determine the target air pressure value of the sand box in the sand spreading device based on the real-time speed of the locomotive and the preset correspondence between speed and pressure compensation.

[0047] When the locomotive speed exceeds a certain value, the sand sprayed from the nozzle will not fall accurately into the target area of ​​the rail surface due to the influence of the speed, which means that the sand cannot effectively fall into the target area, resulting in sand waste. Therefore, in this embodiment, the target air pressure value of the sand box in the sand box device can be determined according to the locomotive speed and the preset correspondence between speed and pressure compensation. The target air pressure value of the sand box can be adjusted by the air source adjustment module in the sand box device.

[0048] In particular, step S202 can be referred to step S102 above, and step S204 can be referred to step S104 above, and will not be repeated here.

[0049] The preset relationship between speed and pressure compensation can be expressed as: , in The target air pressure value; The reference pressure can be 450 kPa. Real-time speed of the locomotive (unit: km / h); This is an empirical compensation coefficient, which can be taken as 0.0025 s / m. For example, when the locomotive is running at 120 km / h, the calculated value is... Therefore, the faster the vehicle speed and the higher the air pressure, the better the sand can resist turbulence and accurately hit the target area (such as under the wheels). This target air pressure value can be sent to the air source regulation module via RS485 interface using the Modbus RTU protocol.

[0050] In one possible implementation, the gas supply regulation module may include a two-stage pressure reduction structure: the first stage is a mechanical safety pressure reducing valve, which sets the upper pressure limit to 650 kPa to prevent overpressure in the upstream gas supply system; the second stage is an electronic proportional pressure reducing valve, which receives a 4–20 mA current signal output from the intelligent control unit to achieve… The electronic proportional pressure reducing valve is precisely adjusted with an accuracy of ±5 kPa. This means the valve controls the target air pressure according to the preset speed and pressure compensation relationship. A 0.5-liter pressure buffer tank can be installed between the two pressure reducing valves to absorb instantaneous high-pressure fluctuations generated during pneumatic pulse unblocking, protecting the upstream air cylinder and piping system.

[0051] In some embodiments, instead of using an electronic proportional pressure reducing valve to control the target air pressure value, other components can be used. For example, a multi-stage parallel solenoid valve group can be used, connecting multiple pressure reducing valves with different orifice diameters or set pressures in parallel. The combined opening (binary encoding) achieves graded pressure regulation (e.g., low-speed valve A opening, high-speed valve A+B opening). Another example is using a variable frequency air compressor: directly adjusting the speed of the source motor that generates compressed air to change the output pressure (slower response, but eliminates the need for a pressure reducing valve). Alternatively, a servo motor can drive the pressure regulating valve, using the servo motor's mechanical rotation to adjust the knob of a regular pressure reducing valve, achieving closed-loop pressure control. These components controlling the target air pressure value all employ dynamic fluid pressure compensation mechanisms, with the common goal of establishing a functional relationship between the execution pressure and the locomotive speed to overcome environmental interferences at high speeds (such as reverse wind pressure and turbulence).

[0052] In this embodiment of the application, the control method may further include the following steps A1, A2 and A3.

[0053] Step A1: Based on the data collected by the sensor installed at the end of the sand conveying pipeline and the real-time sand spreading mode, if it is determined that the sand conveying pipeline is blocked, control the sand spreading device to switch from the sand spreading mode to the pulse unblocking mode. The sensor installed at the end of the sand conveying pipeline can be a microwave Doppler sensor or other sensors capable of determining whether the sand at the end of the sand conveying pipeline is flowing.

[0054] In one implementation, when the real-time sand-spraying mode is not a stopped sand-blasting mode, but rather a continuous sand-blasting mode or a periodically intermittent sand-blasting mode—that is, when the real-time sand-spraying mode indicates that the sand-carrying pipeline is not blocked, and there should be sand flowing near the nozzle at the end of the current sand-carrying pipeline—if the voltage data collected by the microwave Doppler sensor remains below a first voltage threshold for a first preset duration, then the sand-carrying pipeline is determined to be blocked. The first preset duration can be greater than the periodic intermittent sand-blasting cycle. Specifically, the first preset duration can be 500ms, 400ms, etc., while the periodic intermittent sand-blasting cycle can be 30ms, 6ms, or 100ms, but always less than the first preset duration, to avoid misjudging periodically intermittent sand-blasting as a blockage in the sand-carrying pipeline. The first voltage threshold can be 0.3V.

[0055] Step A2: If the sand conveying pipeline is determined to be unobstructed within a preset duration of the pulse unblocking mode, the sand spreading device switches from the pulse unblocking mode to the sand spreading mode. This preset duration can be several cycles of the pulse unblocking mode; that is, within a preset cycle of the pulse unblocking mode (e.g., 2 or 3 cycles), if the voltage data collected by the microwave Doppler sensor at the end of the sand conveying pipeline is greater than a second voltage threshold (e.g., 2.0V), then the sand conveying pipeline is determined to be unobstructed.

[0056] Step A3: If the sand conveying pipeline becomes blocked after the pulse unblocking mode has been running for a preset duration, the sand spreading device will issue a warning message. Specifically, if the voltage data collected by the microwave Doppler sensor at the end of the sand conveying pipeline is not greater than the second voltage threshold (e.g., not greater than 2.0V) after the pulse unblocking mode has been running for more than the preset period (e.g., after 2 or 3 periods), an alarm signal will be issued to prompt manual intervention for the blockage.

[0057] The second voltage threshold can be greater than the first voltage threshold.

[0058] In pulse unblocking mode, the solenoid valve of the sand-spreading device can perform periodic full-open and full-close operations at a frequency of 20Hz and a duty cycle of 100%, i.e., each opening lasts 25ms and each closing lasts 25ms, forming a high-frequency pneumatic pulse. In this mode, due to the rapid opening and closing of the valve, a pressure wave is generated in the pipeline, with a peak pressure that can reach 1.8 times the current reference air pressure (for example, at a reference of 500kPa, the peak pressure reaches 900kPa). This impact effect is used to break up the sand column formed by moisture absorption and caking at the nozzle inlet.

[0059] In pulse unblocking mode, the solenoid valve can perform a periodic full-open and full-close operation at a frequency of 20Hz and a duty cycle of 100% to complete one cycle. The interval between cycles can be 1 second or 1.5 seconds, and each cycle can last for 2 seconds or 3 seconds, so that the microwave Doppler sensor installed at the end of the sand conveying pipeline can collect data and determine whether the sand conveying pipeline has been unblocked.

[0060] The microwave Doppler sensor can be a microwave Doppler solid-gas two-phase flow sensor. This sensor is installed at the end of the sand conveying pipeline, 50mm from the nozzle inlet. Its transmission frequency can be 24.125GHz. It determines the presence of effective solid-phase flow by detecting the Doppler frequency shift caused by moving sand particles. The sensor integrates a mixer, a low-pass filter with a cutoff frequency of 500Hz, and a 12-bit ADC converter with a sampling frequency of 10kHz. The output is a 0–5V analog voltage signal, where 0–0.3V corresponds to no sand flow, 0.3–2.0V to weak or intermittent flow, and above 2.0V to normal full flow. The sensor is connected to the intelligent control unit via a shielded twisted-pair cable no longer than 2 meters. The housing is designed with IP67 protection and coated with a 50μm thick polytetrafluoroethylene coating to prevent sand particles from adhering and affecting microwave transmission performance.

[0061] In some embodiments, instead of using a microwave Doppler sensor to detect frequency shift voltage and determine whether sand is flowing, other sensors can be used for monitoring. For example, an acoustic emission sensor can be used, attached to the pipe wall, to listen to the high-frequency friction sound generated by sand particles hitting the pipe wall; the presence of sound indicates flow, while the absence of sound indicates blockage. Another example is using a capacitive sensor to detect changes in the dielectric constant of the medium inside the pipe; the capacitance value fluctuates as sand flows through, and remains constant when the pipe is blocked or empty. Alternatively, an electrostatic / triboelectric sensor can be used to detect the static charge signal generated by the friction of sand particles flowing inside the pipe; the signal strength is proportional to the flow rate. Yet another example is using a photoelectric beam sensor, with transmitters and receivers placed in transparent pipe sections or openings, using the light-blocking rate (transmittance) of the sand flow to determine whether flow is present. These sensors are all non-invasive flow state sensing technologies. Their core logic is to infer the pipe's flow status by capturing the physical field changes (sound, electricity, light, waves) accompanying the solid-gas two-phase flow without directly obstructing the fluid.

[0062] The solenoid valve of the sand spreading device can be located upstream of the sand box. A pressure buffer tank is installed between the first-stage and second-stage pressure reducing valves in the air supply regulation module of the sand box to smooth out pressure fluctuations generated during the pneumatic pulse unblocking process.

[0063] Below, the applicant will continue to describe other possible implementations of the embodiments of this application.

[0064] In one possible implementation, the control unit (or intelligent control unit) can be deployed in the central control cabinet in the equipment compartment below the locomotive driver's cab. Its hardware platform is an industrial-grade programmable logic controller conforming to the EN 50155 standard, with built-in dual redundant power supply modules and watchdog timers. The intelligent control unit receives track surface status tags from the environmental sensing unit, real-time locomotive speed signals from the Train Network Control System (TCMS), wheelset slip / slip detection signals, and status feedback signals from the self-healing execution unit. The intelligent control unit integrates a PWM signal generator module, which outputs a square wave signal with a frequency of 1kHz and an adjustable duty cycle range of 0% to 100%, used to drive the pneumatic solenoid valve.

[0065] In one possible implementation, the sand-spreading system to which this sand-spreading control method is applied may include a self-healing actuator. This self-healing actuator may include a sand box, a sand conveying pipe, a nozzle, a high-speed PWM solenoid valve, a microwave Doppler solid-gas two-phase flow sensor, and a pneumatic pulse unblocking actuator. The sand box may be made of 6061-T6 aluminum alloy, with a volume of 80 liters, and an internal electric heating layer with a heating power of 300W to maintain sand dryness. The sand conveying pipe may be a 12mm inner diameter, 2mm wall thickness stainless steel 316L flexible hose, with a total length not exceeding 3.5 meters, laid along the locomotive underframe and secured with clamps. The high-speed PWM solenoid valve is a normally closed direct-acting structure with a rated voltage of DC24V, an opening response time ≤5ms, a closing response time ≤8ms, a maximum working pressure of 600kPa, and NPT valve body inlet and outlet. 1 / 2 threaded connection; This microwave Doppler solid-gas two-phase flow sensor can be installed at the end of the sand conveying pipeline, 50mm from the nozzle inlet. Its transmission frequency is 24.125GHz. It determines whether there is effective solid phase flow in the pipe by detecting the Doppler frequency shift caused by sand particle movement. The sensor output is an analog voltage signal, ranging from 0 to 5V, corresponding to no flow to full flow state; The working process of the self-healing execution unit is as follows: When the intelligent control unit issues a sand-spreading command and the duration exceeds 500ms, if the output voltage of the microwave Doppler sensor is lower than 0.3V (corresponding to no sand flow state), it is determined that the pipeline is blocked; the system immediately switches to the pulse unblocking mode. At this time, the intelligent control unit controls the PWM solenoid valve at a frequency of 20Hz and 100 The system operates in a 25ms cycle, with each cycle lasting 25ms, creating a high-frequency pneumatic pulse. This pulse generates a pressure wave within the sand conveying pipeline, with a peak pressure reaching 1.8 times the base pressure. This pressure wave's impact effect shatters the sand column that has hardened due to moisture absorption at the nozzle inlet. The pulse clearing action is executed for three cycles, each lasting two seconds with a one-second interval between cycles. If the microwave Doppler sensor detects sand flow recovery (output voltage ≥ 2.0V) in any cycle, the clearing mode is immediately exited, and normal sand spreading resumes. If there is still no sand flow after three consecutive cycles, a "sand spreading pipeline blockage" fault code is sent to the driver's HMI via the MVB bus, and a red warning light is illuminated.

[0066] In some embodiments, the pulse unblocking mode can be implemented without using a PWM solenoid valve. For example, a mechanical tapping / vibrating device can be used, with an eccentric wheel motor or pneumatic tapping hammer installed at the easily blocked area to generate low-frequency, high-energy mechanical impact. Another example is the use of a bypass high-pressure backflush (Bypass Air Jet), where an independent high-pressure air pipe is connected in parallel at the nozzle, directly introducing unreduced high-pressure airflow for reverse or tangential impact when blocked. Alternatively, a heating melting device can be used, wrapping an electric heating cable or high-power heating resistor around the nozzle for blockages caused by icing. Yet another example is mechanical stirring / unblocking, where airflow-driven rotating blades or springs are installed inside the nozzle to physically break up the clumps. These unblocking modes are all active energy injection decoupling technologies; their core principle is to inject additional physical energy (shock wave, vibration energy, thermal energy, mechanical energy) into the deposited / caking area, disrupting the structural stability of the blockage and restoring flow channel patency.

[0067] In one possible implementation, the sand conveying pipe can have a locally enlarged section near the nozzle, with its inner diameter increased from 12mm to 18mm and its length increased to 80mm. This section reduces the sand flow velocity and minimizes erosion and wear on the nozzle throat. An ultrasonic vibration patch, made of piezoelectric ceramic material PZT-5H and measuring 20mm × 10mm × 1mm, with a resonant frequency of 40kHz, is welded 50mm upstream of the enlarged section. The control unit (i.e., the intelligent control unit) can immediately apply a sinusoidal excitation signal with an amplitude of 120Vpp and a duration of 100ms to this patch after each sand-spraying command, generating high-frequency mechanical vibration to remove residual sand particles adhering to the pipe wall and prevent long-term accumulation that could lead to blockage.

[0068] The signal processing circuit of the microwave Doppler solid-gas two-phase flow sensor can be integrated into the sensor body and may include a mixer, a low-pass filter and an ADC converter, with a sampling frequency of 10kHz. The sensor is connected to the intelligent control unit via a shielded twisted pair cable with a transmission distance of no more than 2 meters to suppress electromagnetic interference. The sensor housing is designed with an IP67 protection rating and is coated with polytetrafluoroethylene to prevent sand particles from adhering and affecting measurement accuracy.

[0069] The intelligent control unit has a built-in fault recording module, which uses a non-volatile FRAM memory with a capacity of 2MB to record the timestamp, rail surface status, locomotive speed, actual air pressure, sand flow status, and number of clearing attempts for each sand-spreading event. The recorded data can be exported via USB interface for subsequent adhesion performance analysis and system maintenance.

[0070] The nozzle features a venturi design with a 6mm throat diameter and an 8° diffusion angle. It is made of 316L stainless steel with a 150μm thick tungsten carbide coating, significantly improving its wear resistance and lifespan. The nozzle outlet axis forms a 15° angle with the track plane, ensuring that the sand flow accurately falls within 180-220mm in front of the wheel-rail contact patch under a pressure of 450-600kPa. An integrated reed-type anti-backflow check valve can be installed inside the nozzle, with an opening pressure of 50kPa and a closing response time of ≤10ms, effectively preventing rainwater or snowmelt from flowing back into the sand conveying pipeline.

[0071] The aforementioned pulse clearing action can be executed periodically: each cycle lasts 2 seconds, for a total of 3 cycles, with a 1-second interval between cycles. Within any cycle, if the microwave Doppler sensor detects that the output voltage rises to ≥2.0V and remains above 100ms, the sand flow is considered restored, the system immediately exits the clearing mode, resumes normal sand application, and records the successful clearing event. If the sensor output remains below 0.3V after 3 consecutive cycles (a total of 8 seconds), it is considered a severe blockage that cannot heal itself; at this time, the intelligent control unit sends the fault code "E107: Sand application pipeline blockage" to the driver's cab human-machine interface (HMI) via the MVB bus and illuminates a red warning light, prompting the crew to intervene manually.

[0072] The aforementioned intelligent control unit incorporates a fault recording module using a non-volatile FRAM memory with a capacity of 2MB and a write endurance of 10^14 cycles. This module records complete contextual information for each sand-spreading event, including: event start timestamp (UTC format), track surface condition category, locomotive speed (km / h), target air pressure Pout (kPa), actual air pressure feedback value (from the pressure sensor built into the proportional pressure reducing valve), microwave Doppler sensor output voltage (V), sand-spreading duration (ms), whether clearing was triggered, number of clearing attempts, and final status (success / failure). All recorded data can be exported as a CSV file via the front panel USB 2.0 interface for the ground maintenance system to perform adhesion performance trend analysis, sand consumption statistics, and fault root cause tracing.

[0073] Below, the applicant will explain some of the technical terms used in this application.

[0074] PWM (Pulse Width Modulation) is a control technique that controls output energy by rapidly switching a power supply on and off (adjusting the duty cycle). Here, it's used to control the opening and closing of a solenoid valve, achieving "intermittent injection" or controlling the flow rate.

[0075] A microwave Doppler sensor is a miniature radar that emits microwaves. When the waves encounter moving sand grains, their frequency changes (Doppler effect). By detecting this frequency change, it is possible to determine whether there is sand flowing inside the pipe.

[0076] Gas-solid two-phase flow refers to the state in which gas (compressed air) and solid particles (sand) are mixed together and flow together.

[0077] A Venturi structure is a pipe design that is narrow in the middle and wide at both ends. When airflow passes through the narrow middle section, its speed increases and its pressure decreases, thereby generating suction or more efficiently blowing sand.

[0078] CAN FD, MVB, and RS485 are all communication cable standards used for communication between industrial devices. Among them, CAN FD has a fast transmission speed (transmitting image results), MVB is a dedicated bus for trains (transmitting train speed), and RS485 is used for simple device control (regulating air pressure).

[0079] The CMOS image sensor is the core chip of a digital camera, responsible for converting light signals into digital image signals.

[0080] FRAM (Ferroelectric RAM) is a type of memory chip with extremely fast read and write speeds and no data loss after power failure. It is used to record fault logs and is more durable than ordinary flash memory.

[0081] This application embodiment also provides a sand spreading system, including a sand spreading device and a control unit. The control unit is connected to the sand spreading device, which is installed at the bottom of the locomotive and is used to spread sand on the rail surface of the wheel rail to be contacted in the forward direction of the locomotive. The control unit is used to execute the control method described above. This sand spreading system can achieve the technical effects of the sand spreading control method described above, which will not be elaborated here.

[0082] This application also provides a locomotive that can include the above-mentioned sand spreading system and achieve the technical effects of the sand spreading system, which will not be described in detail here.

[0083] Figure 3 The diagram shows a structural schematic of a sand-spreading control device 100 provided in an embodiment of this application. The device 100 includes a rail surface category determination module 110 and a sand-spreading mode determination module 120.

[0084] The rail surface category determination module 110 is used to determine the rail surface category of the rail to be contacted based on the image frame sequence collected by the environmental perception unit of the sand spreading device on the rail surface of the rail to be contacted in the direction of locomotive travel. The rail surface category includes at least one of dry, slightly wet, water accumulation, ice, and oil stains. The sand-spraying mode determination module 120 is used to determine the sand-spraying mode of the sand-spraying device on the rail surface of the wheel and rail to be contacted, based on the rail surface type of the wheel and rail to be contacted.

[0085] In one embodiment, the sand spraying mode includes: continuous sand spraying, periodic intermittent sand spraying, and stopped sand spraying; The step of determining the sand-spreading mode of the sand-spreading device on the rail surface of the wheel and rail to be contacted, based on the rail surface type, includes at least one of the following: If the rail surface category is icing and / or oil contamination, the sanding mode is determined to be continuous sandblasting; When the rail surface type is slightly wet and / or has accumulated water, the sanding mode is determined to be periodic intermittent sandblasting; If the rail surface category is dry, the sanding mode is determined to be stop sandblasting.

[0086] In one embodiment, the environmental sensing unit includes a multispectral polarization imaging module; the environmental sensing unit is located below the front end of the locomotive obstacle clearer and / or on the front side of the bogie frame; The sequence of image frames acquired by the environmental sensing unit of the sand-spreading device from the rail surface of the wheel-rail to be contacted in the direction of locomotive travel includes: The multispectral polarization imaging module acquires multiple image frames of the track surface of the wheel-rail to be contacted along the locomotive's forward direction for a length not less than a first preset length, thereby determining the track surface type of the wheel-rail to be contacted; the image frame sequence includes multiple image frames.

[0087] In one embodiment, the sand spreading device includes a sand box, a sand conveying pipe and a nozzle that are interconnected, as well as a signal generator and a solenoid valve, the solenoid valve being used to control compressed air entering the sand conveying pipe; The sand-spreading device 100 is also used for: Based on the sand-spraying mode, the duty cycle of the control signal output by the signal generator is determined, and the signal generator outputs the control signal to the solenoid valve.

[0088] In one embodiment, the sand-spreading device 100 is further used for: Based on the locomotive's real-time speed and the preset correspondence between speed and pressure compensation, the target air pressure value of the sand box in the sand spreading device is determined.

[0089] In one embodiment, the sand-spreading device 100 is further used for: Based on the data collected by the sensor installed at the end of the sand conveying pipeline and the real-time sand spreading mode, if it is determined that the sand conveying pipeline is blocked, the sand spreading device is controlled to switch from the sand spreading mode to the pulse unblocking mode. If the sand conveying pipeline is determined to be unobstructed within the preset duration of the pulse unblocking mode, the sand spreading device switches from the pulse unblocking mode to the sand spreading mode. If the sand conveying pipeline becomes blocked after the pulse unblocking mode has been running for a preset duration, the sand spreading device will issue a warning message.

[0090] In one embodiment, the sand-spreading device 100 is further configured to: in the pulse unblocking mode, the solenoid valve of the sand-spreading device periodically open and close with a 100% duty cycle.

[0091] In one embodiment, the step of determining the blockage status of the sand conveying pipeline based on data collected by a sensor located at the end of the sand conveying pipeline in the sand spreading device 100 includes: If the voltage data collected by the microwave Doppler sensor at the end of the sand conveying pipeline remains below the first voltage threshold for a first preset duration, and the real-time sand spraying mode is not a stop sand spraying mode, then the sand conveying pipeline is determined to be blocked. If, within a preset duration of the pulse unblocking mode, the sand conveying pipeline is determined to be unobstructed, the sand spreading device switches from the pulse unblocking mode to the sand spreading mode, including: If the voltage data collected by the microwave Doppler sensor at the end of the sand conveying pipeline is greater than the second voltage threshold during the preset period of the pulse unblocking mode, it is determined that the sand conveying pipeline is unobstructed, and the second voltage threshold is greater than the first voltage threshold. After the pulse unblocking mode has been in effect for a preset duration, if the sand conveying pipeline is determined to be blocked, the sand spreading device will issue a warning message, including: If the voltage data collected by the microwave Doppler sensor at the end of the sand conveying pipeline is less than or equal to the second voltage threshold after the pulse unblocking mode continues for more than the preset period, an alarm signal will be issued.

[0092] The device 100 provided in this application embodiment can execute the methods described in the preceding method embodiments and achieve the functions and beneficial effects of the methods described in the preceding method embodiments, which will not be repeated here.

[0093] Figure 3 The diagram illustrates the hardware structure of an electronic device implementing the embodiments of this application. Referring to the diagram, at the hardware level, the electronic device includes a processor and optionally, an internal bus, a network interface, and a memory. The memory may include RAM, such as high-speed random-access memory (RAM), or non-volatile memory, such as at least one disk storage device. Of course, the electronic device may also include other hardware required for other services.

[0094] The processor, network interface, and memory can be interconnected via an internal bus, which can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. This bus can be categorized as an address bus, data bus, control bus, etc. For ease of illustration, only a single bidirectional arrow is used in this diagram, but this does not imply that there is only one bus or one type of bus.

[0095] Memory is used to store programs. Specifically, programs may include program code, which includes computer operation instructions. Memory may include main memory and non-volatile memory, and provides instructions and data to the processor.

[0096] The processor reads the corresponding computer program from non-volatile memory into main memory and then executes it, forming a device at the logical level that locates the target user. The processor executes the program stored in memory and specifically performs the following: Figure 1-2 The methods disclosed in the embodiments shown achieve the functions and beneficial effects of the methods described in the preceding method embodiments, and will not be repeated here.

[0097] The above is as stated in this application. Figure 1-2The methods disclosed in the illustrated embodiments can be applied to or implemented by a processor. The processor may be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above method can be completed by integrated logic circuits in the processor's hardware or by instructions in software form. The processor can be a general-purpose processor, including a Central Processing Unit (CPU), a Network Processor (NP), etc.; it can also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this application can be directly embodied in the execution of a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor. The software module can reside in a mature storage medium in the field, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, or registers. This storage medium is located in memory, and the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method.

[0098] The electronic device can also execute the methods described in the preceding method embodiments and achieve the functions and beneficial effects of the methods described in the preceding method embodiments, which will not be repeated here.

[0099] Of course, in addition to software implementation, the electronic device of this application does not exclude other implementation methods, such as logic devices or a combination of hardware and software, etc. In other words, the execution subject of the following processing flow is not limited to each logic unit, but can also be hardware or logic devices.

[0100] This application also proposes a computer-readable storage medium that stores one or more programs, which, when executed by an electronic device including multiple applications, cause the electronic device to perform... Figure 1-2 The methods disclosed in the embodiments shown achieve the functions and beneficial effects of the methods described in the preceding method embodiments, and will not be repeated here.

[0101] The computer-readable storage medium mentioned above includes read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk, etc.

[0102] Furthermore, embodiments of this application also provide a computer program product, the computer program product including a computer program stored on a non-transitory computer-readable storage medium, the computer program including program instructions, which, when executed by a computer, implement the following process: Figure 1 The methods disclosed in the embodiments shown achieve the functions and beneficial effects of the methods described in the preceding method embodiments, and will not be repeated here.

[0103] In summary, the above description is merely a preferred embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

[0104] The systems, devices, modules, or units described in the above embodiments can be implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, a computer can be, for example, a personal computer, laptop computer, cellular phone, camera phone, smartphone, personal digital assistant, media player, navigation device, email device, game console, tablet computer, wearable device, or any combination of these devices.

[0105] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0106] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0107] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

Claims

1. A method for controlling sand spreading, characterized in that, include: Based on the image frame sequence collected by the environmental sensing unit of the sand spreading device on the rail surface of the wheel and rail to be contacted in the direction of locomotive travel, the rail surface category of the wheel and rail to be contacted is determined, and the rail surface category includes at least one of dry, slightly wet, water accumulation, ice and oil stains. Based on the rail surface type of the wheel and rail to be contacted, the sand-spreading mode of the sand-spreading device on the rail surface to be contacted is determined.

2. The control method according to claim 1, characterized in that, The sand-spraying modes include: continuous sandblasting, periodic intermittent sandblasting, and stopped sandblasting; Based on the rail surface type of the wheel and rail to be contacted, the sanding mode of the sanding device on the rail surface to be contacted is determined, including at least one of the following: If the rail surface category is icing and / or oil contamination, the sanding mode is determined to be continuous sandblasting; When the rail surface type is slightly wet and / or has accumulated water, the sanding mode is determined to be periodic intermittent sandblasting; If the rail surface category is dry, the sanding mode is determined to be stop sandblasting.

3. The control method according to claim 1, characterized in that, The environmental perception unit includes a multispectral polarization imaging module; the environmental perception unit is located below the front end of the locomotive obstacle remover and / or on the front side of the bogie frame. The sequence of image frames acquired by the environmental sensing unit of the sand-spreading device from the rail surface of the wheel-rail to be contacted in the direction of locomotive travel includes: The multispectral polarization imaging module acquires multiple image frames of the track surface of the wheel-rail to be contacted along the locomotive's forward direction for a length not less than a first preset length, thereby determining the track surface type of the wheel-rail to be contacted; the image frame sequence includes multiple image frames.

4. The control method according to claim 1, characterized in that, The sand spreading device includes a sand box, a sand conveying pipe and a nozzle that are interconnected, as well as a signal generator and a solenoid valve. The solenoid valve is used to control the compressed air entering the sand conveying pipe. The method further includes: Based on the sand-spraying mode, the duty cycle of the control signal output by the signal generator is determined, and the signal generator outputs the control signal to the solenoid valve.

5. The control method according to claim 1, characterized in that, The method further includes: Based on the locomotive's real-time speed and the preset correspondence between speed and pressure compensation, the target air pressure value of the sand box in the sand spreading device is determined.

6. The control method according to claim 1, characterized in that, The method further includes: Based on the data collected by the sensor installed at the end of the sand conveying pipeline and the real-time sand spreading mode, if it is determined that the sand conveying pipeline is blocked, the sand spreading device is controlled to switch from the sand spreading mode to the pulse unblocking mode. If the sand conveying pipeline is determined to be unobstructed within the preset duration of the pulse unblocking mode, the sand spreading device switches from the pulse unblocking mode to the sand spreading mode. If the sand conveying pipeline is determined to be blocked after the pulse unblocking mode has been in effect for a preset duration, the sand spreading device will issue a warning message.

7. The control method according to claim 6, characterized in that, In the pulse unblocking mode, the solenoid valve of the sand spreading device performs periodic full-open and full-close operations with a 100% duty cycle.

8. The control method according to claim 6, characterized in that, The step of determining the blockage status of the sand conveying pipeline based on data collected by sensors installed at the end of the pipeline includes: If the voltage data collected by the microwave Doppler sensor at the end of the sand conveying pipeline remains below the first voltage threshold for a first preset duration, and the real-time sand spraying mode is not a stop sand spraying mode, then the sand conveying pipeline is determined to be blocked. If, during the preset duration of the pulse unblocking mode, it is determined that the sand conveying pipeline is unobstructed, the sand spreading device switches from the pulse unblocking mode to the sand spreading mode, including: If the voltage data collected by the microwave Doppler sensor at the end of the sand conveying pipeline is greater than the second voltage threshold during the preset period of the pulse unblocking mode, it is determined that the sand conveying pipeline is unobstructed, and the second voltage threshold is greater than the first voltage threshold. After the pulse unblocking mode has been in effect for a preset duration, if the sand conveying pipeline is determined to be blocked, the sand spreading device will issue a warning message, including: If the voltage data collected by the microwave Doppler sensor at the end of the sand conveying pipeline is less than or equal to the second voltage threshold after the pulse unblocking mode continues for more than the preset period, an alarm signal will be issued.

9. A sand-spreading system, characterized in that, Includes a sand spreading device and a control unit; The control unit is connected to the sand spreading device, which is installed at the bottom of the locomotive and is used to spread sand on the rail surface of the wheel rail to be contacted in the forward direction of the locomotive. The control unit is used to perform the method as claimed in any one of claims 1-8.

10. A locomotive, characterized in that, Including the sand-spreading system as described in claim 9.

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