Industrial control system for asphalt pavement crack melting and injection process

Abstract

The present application relates to the technical field of industrial control system, and particularly relates to an industrial control system for a melting and filling process of asphalt pavement cracks. The system comprises a multi-source sensing acquisition front end, a heat-flow coupling compensation operation core and an actuator driving end. The multi-source sensing acquisition front end acquires real-time temperature, pressure and flow rate signals of asphalt at a nozzle. The heat-flow coupling compensation operation core inverses the real-time temperature into a dynamic viscosity parameter based on a viscosity-temperature characteristic equation, inputs the dynamic viscosity parameter and the flow rate signal into a resistance compensation model to calculate a dynamic pressure difference compensation value. The actuator driving end rewrites a variable frequency filling pump speed control program according to the dynamic pressure difference compensation value, and corrects a heater pulse width modulation duty cycle based on a fluid heat absorption rate deviation caused by speed variation. The present application overcomes the filling resistance imbalance and uneven filling defects caused by sudden viscosity increase of asphalt due to heat loss, avoids thermal aging or incomplete melting caused by asynchronous temperature control and flow control, and improves system operation stability.

Description

Technical Field

[0001] This invention relates to the field of industrial control system technology, and more specifically to an industrial control system for the asphalt pavement crack fusion injection process. Background Technology

[0002] Industrial control systems for asphalt pavement crack melting and grouting typically employ a closed-loop architecture where temperature control and flow control are independent. The temperature control loop uses a temperature sensor to collect the asphalt temperature within the heating pipe and transmits the signal to a temperature controller. The temperature controller compares the measured temperature with the target set temperature and, based on the deviation, outputs a pulse width modulation signal to adjust the heater's output power until the measured temperature approaches the set temperature. The flow control loop uses a flow sensor to collect the asphalt flow velocity at the grouting nozzle and feeds the velocity signal back to a flow controller. The flow controller outputs a speed control command to the variable frequency grouting pump based on the set target flow velocity, maintaining a constant grouting flow rate. In this architecture, the operating logic of the heater and the variable frequency grouting pump does not interfere with each other; the temperature control loop is only responsible for eliminating temperature deviations, and the flow control loop is only responsible for maintaining a stable flow rate.

[0003] In actual asphalt pavement grouting operations, when molten asphalt is injected into cracks through nozzles, it encounters intense heat exchange with the cold walls of the ambient-temperature pavement, causing a sharp drop in asphalt temperature within a very short time. As a highly temperature-sensitive non-Newtonian fluid, asphalt's dynamic viscosity increases exponentially with decreasing temperature. This sudden increase in local viscosity caused by heat loss alters the friction resistance characteristics within the pipeline. At this time, the flow control loop continues to drive the variable frequency grouting pump according to the original settings. Because it fails to detect the sudden change in pipeline resistance, the output pressure of the variable frequency grouting pump is insufficient to overcome the surge in friction resistance, resulting in a momentary decrease or even interruption of the grouting flow rate. To restore the flow rate, operators often need to manually increase the set flow rate or increase the heating power. However, this delayed manual intervention cannot synchronously match the dynamic process of heat loss and resistance changes, easily leading to localized incomplete melting or surface overheating.

[0004] The core technical problem of thermal-fluid dynamic mismatch exists in the existing industrial control system for the asphalt pavement crack melting and grouting process. Because the temperature control and flow control loops operate independently, the flow control loop cannot capture the abrupt change in the thermodynamic state of the asphalt upon contact with the cold pavement wall during grouting, nor can it use fluid thermodynamic parameters as feedforward compensation for the flow program control. When the asphalt experiences severe heat loss upon contact with the pavement cold wall, triggering a dramatic nonlinear increase in dynamic viscosity, the independently operating flow control program lacks the dynamic response and adaptive adjustment capability to handle sudden changes in friction resistance. This leads to a severe imbalance between the output pressure of the variable frequency grouting pump and the actual pipeline resistance, ultimately causing deep cracks to fill with voids and grouting to be interrupted. Summary of the Invention

[0005] The purpose of this invention is to provide an industrial control system for the asphalt pavement crack melting and grouting process, which can effectively solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: An industrial control system for the asphalt pavement crack melting and grouting process includes a multi-source sensor acquisition front-end, a thermal-fluid coupling compensation calculation core, and an actuator drive end; The multi-source sensor acquisition front end acquires real-time temperature, pressure and flow rate signals of the asphalt at the injection nozzle; The core of the thermal-fluid coupling compensation calculation is based on the viscosity-temperature characteristic equation of asphalt non-Newtonian fluid to invert the real-time temperature signal into dynamic viscosity parameters, and inputs the dynamic viscosity parameters and the flow velocity signal into the preset resistance compensation model to calculate the dynamic pressure difference compensation value. The actuator drive end rewrites the speed control program of the variable frequency injection pump in real time according to the dynamic differential pressure compensation value, and corrects the pulse width modulation duty cycle of the heater based on the fluid heat absorption rate deviation caused by the speed change, forming a temperature-flow coordinated closed-loop program control.

[0007] Preferably, the multi-source sensing acquisition front end includes a multi-point temperature sensor array and a differential pressure sensor disposed in the infusion pipeline; The multi-point temperature sensor array collects discrete temperature field signals distributed axially in the pipeline, and the differential pressure sensor collects differential pressure fluctuation signals before and after the nozzle. The multi-source sensing acquisition front end removes thermal noise from the discrete temperature field signal by means filtering through a sliding window, extracts the temperature drop slope as a heat dissipation characteristic, and synchronously aligns the heat dissipation characteristic with the pressure difference fluctuation signal to the heat-flow coupling compensation calculation core.

[0008] Preferably, the heat-fluid coupling compensation calculation core is embedded with a viscosity-temperature characteristic equation that is dynamically updated with the aging degree of asphalt; The heat-fluid coupling compensation calculation core extracts the cumulative heating time and historical peak temperature, calculates the asphalt aging index, and uses the asphalt aging index to reduce the order of the coefficient of the exponential term in the standard viscosity-temperature characteristic equation to obtain the real-time viscosity-temperature characteristic equation. The real-time viscosity-temperature characteristic equation maps the real-time temperature signal to the dynamic viscosity parameter that takes into account the thermal degradation effect.

[0009] Preferably, the resistance compensation model constructs a correlation mapping between the dynamic viscosity parameter and the pipe friction loss; The heat-fluid coupling compensation calculation core inputs the dynamic viscosity parameter and the flow velocity signal into the resistance compensation model, calculates the theoretical friction loss under the current viscosity and flow velocity according to the Hagen-Poiseuille equation, and calculates the difference between the theoretical friction loss and the reference pressure loss. The difference is then used as the dynamic differential pressure compensation value and output to the actuator drive end.

[0010] Preferably, the actuator drive end converts the dynamic differential pressure compensation value into the speed compensation increment of the variable frequency injection pump and adds it to the original speed setting value; The actuator drive end calculates the fluid heat absorption rate at the current flow rate based on the real-time rotation speed of the variable frequency injection pump, and calculates the heat balance deviation between the fluid heat absorption rate and the current output power of the heater. Based on the heat balance deviation, the pulse width of the pulse width modulation duty cycle is dynamically adjusted to compensate for the heat deviation caused by the change in the residence time of the fluid in the heating zone due to the change in rotation speed.

[0011] Preferably, after receiving the heat dissipation characteristic quantity and the pressure difference fluctuation signal, the heat-fluid coupling compensation calculation core calculates the rate of change of the heat dissipation characteristic quantity and the phase difference between the pressure difference fluctuation signal; When the phase difference exceeds the preset hysteresis threshold, it is determined that a local solidification blockage has occurred in the infusion pipeline; The thermal-fluid coupling compensation calculation core generates a pulse backflush command and sends it to the actuator drive end. The actuator drive end controls the variable frequency injection pump to instantly reverse and resume forward rotation, using transient reverse pressure impact to peel off the initial set asphalt in the local solidification blockage state.

[0012] Preferably, when calculating the asphalt aging index, the heat-fluid coupling compensation calculation core introduces the extreme envelope of the real-time temperature signal for integration calculation to obtain the cumulative heat load value; The heat-fluid coupling compensation calculation core substitutes the cumulative heat load value into a piecewise linear function containing the critical heat load boundary. When the cumulative heat load value crosses the critical heat load boundary, the slope coefficient of the order reduction correction is switched, and the step change of the dynamic viscosity parameter caused by the switch of the slope coefficient in the real-time viscosity-temperature characteristic equation is smoothly transitioned by the Lagrange interpolation method.

[0013] Preferably, before calculating the theoretical friction loss, the thermal-fluid coupling compensation calculation core performs high-pass filtering on the flow velocity signal to extract high-frequency pulsation components. The high-frequency pulsation component characterizes the degree of gas phase entrainment within the infusion pipeline; The heat-fluid coupling compensation calculation core calculates the air resistance compensation coefficient based on the amplitude of the high-frequency pulsation component, and multiplies the air resistance compensation coefficient by the theoretical pressure drop along the friction to obtain the corrected theoretical pressure drop along the friction, so as to eliminate the interference of gas phase compression on the calculation of the dynamic pressure difference compensation value.

[0014] Preferably, the multi-source sensor acquisition front end also acquires ambient temperature and road surface temperature; Before starting the grouting program, the thermal-fluid coupling compensation calculation core calculates the average thermal radiation potential of the ambient temperature and the road surface temperature, and obtains the initial heating power setting value and the initial pumping back pressure value by querying the pre-stored initial power matching table based on the difference between the average thermal radiation potential and the target grouting temperature. During the cold start phase, the actuator drive operates according to the initial heating power setting value and the initial pumping back pressure value until the real-time temperature signal reaches the critical temperature range of phase change, after which it switches to the temperature-flow coordinated closed-loop program control.

[0015] Preferably, the heat-fluid coupling compensation calculation core monitors the rate of change of the pressure signal in real time; When the rate of change of the pressure signal reaches an inflection point from negative to positive and the flow velocity signal remains unchanged, it is determined that the bottom of the crack has been sealed by molten asphalt. The heat-fluid coupling compensation calculation core calculates the actual volume of the current crack based on the cumulative injection flow rate when the inflection point occurs, and corrects the step distance of the subsequent injection stroke based on the ratio of the actual volume to the preset calibration volume. At the same time, the actuator drive end switches the speed control program of the variable frequency injection pump to the pressure holding and slowing mode.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention uses a heat-flow coupling compensation calculation core to invert real-time temperature signals into dynamic viscosity parameters. These dynamic viscosity parameters, along with flow velocity signals, are input into a resistance compensation model to calculate dynamic differential pressure compensation values, achieving a deep integration of thermodynamic state and flow control. When asphalt contacts the cold wall of the pavement and experiences heat loss, the dramatic increase in dynamic viscosity parameters is captured in real time and used as a feedforward compensation input. The actuator drive rewrites the speed control program of the variable frequency injection pump based on the dynamic differential pressure compensation value, enabling the pumping pressure to synchronously overcome the frictional resistance caused by the increased viscosity, avoiding flow rate attenuation and void filling. The heater pulse width modulation duty cycle is corrected based on the fluid heat absorption rate deviation caused by the variable frequency injection pump speed change, eliminating the interference of flow fluctuations on thermal balance and preventing local overheating or incomplete melting. A multi-point temperature sensor array extracts the temperature drop slope as a heat loss characteristic quantity and aligns it with the differential pressure fluctuation signal for transmission, improving the real-time performance of the heat loss response. The asphalt aging index is calculated using accumulated heating time and historical peak temperature to perform a reduction-order correction on the viscosity-temperature characteristic equation, ensuring the accuracy of the dynamic viscosity parameter inversion. The theoretical pressure drop along the pressure path is calculated based on the Hagen-Poiseuille equation, and the difference between this and the baseline pressure drop is used as the dynamic pressure difference compensation value, thus giving the pressure difference compensation a fluid dynamics and physical basis.

[0017] 2. The core of the heat-fluid coupling compensation calculation generates a pulse backflush command when the phase difference between the rate of change of the heat dissipation characteristic quantity and the pressure difference fluctuation signal exceeds the hysteresis threshold. This command controls the variable frequency injection pump to instantly reverse and then resume forward rotation, using transient reverse pressure impact to peel off the initial asphalt and overcome the local solidification blockage in the pipeline. The cumulative heat load value is obtained by integrating the extreme envelope of the real-time temperature signal. The slope coefficient of the reduced-order correction is switched through a piecewise linear function and smoothed using interpolation, eliminating the oscillation impact of abrupt changes in the dynamic viscosity parameter on the control system. High-pass filtering of the flow velocity signal extracts high-frequency pulsating components to calculate the air resistance compensation coefficient, correcting the theoretical pressure drop along the pipeline and eliminating interference from gas phase inclusions on the pressure difference compensation. The average thermal radiation potential is calculated based on the ambient and road surface temperatures, and the initial power matching table is consulted. During the cold start phase, the initial heating power and pump back pressure are directly obtained, avoiding control blind spots in the initial cold start stage. When the rate of change of the pressure signal reaches an inflection point from negative to positive and the flow rate remains constant, the actual volume of the crack is calculated and the subsequent step distance is corrected. At the same time, the pressure holding and slow setting mode is switched to realize the identification of the sealing status at the bottom of the crack and the adaptive termination of the injection stroke. Attached Figure Description

[0018] Figure 1 This is a flowchart of the overall heat-fluid coordinated closed-loop full-link control of the asphalt pavement crack melting and grouting industrial control system of the present invention; Figure 2 This is a flowchart of the multi-source sensor acquisition front-end signal noise reduction, heat dissipation feature extraction, and pipeline blockage fault pulse backflow handling process of the present invention. Figure 3This is a flowchart of the process for solving the asphalt aging coefficient and smoothing the viscosity-temperature characteristic equation based on cumulative heat load, as per the present invention. Figure 4 This is a flowchart of the flow rate signal filtering and denoising, gas phase inclusion quantization, and theoretical pressure drop and air resistance compensation and correction calculation of the present invention. Figure 5 This is a flowchart of the cold start phase environmental road surface temperature acquisition, initial operating parameter lookup configuration, and closed-loop control switching process of the present invention. Figure 6 This is a flowchart illustrating the crack sealing status determination, crack volume calculation, and pressure-holding and retardation mode switching control of the grouting equipment according to the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Please refer to Figure 1 This embodiment provides an industrial control system for the asphalt pavement crack grouting process, applied to asphalt crack grouting operations in road maintenance engineering. The system consists of three parts: a multi-source sensor acquisition front-end, a thermal-fluid coupling compensation calculation core, and an actuator drive end. The multi-source sensor acquisition front-end is deployed in the pipeline system and nozzles of the grouting equipment to collect physical quantity signals related to the asphalt fluid state in real time during the grouting process. The thermal-fluid coupling compensation calculation core, as the system's processing center, receives signals sent by the multi-source sensor acquisition front-end, executes preset calculation logic, and generates control commands. The actuator drive end receives control commands sent by the thermal-fluid coupling compensation calculation core and directly drives the variable frequency grouting pump and heater in the grouting equipment to perform corresponding actions.

[0021] Specifically, during the injection operation, the multi-source sensor acquisition front-end continuously acquires real-time temperature, pressure, and flow rate signals of the asphalt at the injection nozzle. The real-time temperature signal reflects the thermodynamic state of the asphalt at the nozzle outlet, the real-time pressure signal reflects the fluid pressure distribution inside the pipeline, and the real-time flow rate signal reflects the injection flow rate of the asphalt. After performing analog-to-digital conversion on the acquired signals, the multi-source sensor acquisition front-end transmits them to the thermal-fluid coupling compensation calculation core via an industrial fieldbus.

[0022] After receiving the real-time temperature signal, the thermal-fluid coupling compensation calculation core inverts the real-time temperature signal into dynamic viscosity parameters based on the viscosity-temperature characteristic equation of asphalt non-Newtonian fluid. As a highly temperature-sensitive non-Newtonian fluid, asphalt exhibits a significant nonlinear correlation between its dynamic viscosity and temperature, which can be quantitatively described by the viscosity-temperature characteristic equation. In this embodiment, the viscosity-temperature characteristic equation adopts the form of the Andrade equation, specifically expressed as: (1) in, The dynamic viscosity of asphalt is expressed in Pa·s. is the pre-index factor, a constant related to the asphalt grade; B is the viscosity-temperature index, a constant related to the asphalt molecular structure; T is the absolute temperature of the asphalt, in K. The heat-fluid coupling compensation calculation core converts the collected real-time Celsius temperature into absolute temperature, substitutes it into the above equation, and calculates the dynamic viscosity parameters of the asphalt at the current temperature.

[0023] The heat-fluid coupling compensation calculation core inputs the calculated dynamic viscosity parameters and the received real-time flow velocity signal into a preset resistance compensation model to calculate the dynamic pressure difference compensation value. The resistance compensation model is used to establish a quantitative correlation between the dynamic viscosity, flow velocity, and pipeline friction loss of the asphalt fluid, thereby predicting the required pumping pressure based on the current fluid state. In this embodiment, the resistance compensation model is based on the Hagen-Poiseuille equation in fluid mechanics, which describes the relationship between the friction loss of a Newtonian fluid in laminar flow in a circular pipe and the fluid viscosity, flow velocity, and pipeline parameters. Since the flow characteristics of molten asphalt within the operating temperature range are approximately similar to those of a Newtonian fluid, this equation is suitable for calculating the pressure drop in this system. The specific expression of the Hagen-Poiseuille equation is: (2) in, The theoretical pressure drop along the pressure line is expressed in Pa. ρ is the dynamic viscosity of asphalt, in Pa·s; L is the pipeline length from the outlet of the variable frequency injection pump to the inlet of the injection nozzle, in meters; Q is the volumetric flow rate of asphalt, in m³ / s; R is the inner radius of the pipeline, in meters. The volumetric flow rate Q can be obtained by comparing the real-time flow velocity signal v with the cross-sectional area of ​​the pipeline. The product is calculated as follows: .

[0024] The thermal-fluid coupling compensation calculation core calculates the difference between the theoretical friction drop and the preset reference pressure drop, and outputs this difference as the dynamic differential pressure compensation value to the actuator drive end. The reference pressure drop is the friction drop required in the pipeline under standard operating conditions, i.e., when the asphalt temperature is the target injection temperature and the flow rate is the set flow rate. The dynamic differential pressure compensation value reflects the resistance difference between the current fluid state and the standard operating conditions. When the asphalt temperature decreases, leading to an increase in dynamic viscosity, the theoretical friction drop increases, and the dynamic differential pressure compensation value is positive, indicating that the pumping pressure needs to be increased to overcome the increased friction resistance. When the asphalt temperature increases, leading to a decrease in dynamic viscosity, the theoretical friction drop decreases, and the dynamic differential pressure compensation value is negative, indicating that the pumping pressure needs to be reduced to avoid excessive flow rate. The specific expression for the dynamic differential pressure compensation value is: (3) in, This is the dynamic differential pressure compensation value, in Pa. The theoretical pressure drop along the pressure line is expressed in Pa. The reference pressure drop is expressed in Pa.

[0025] After receiving the dynamic differential pressure compensation value, the actuator drive rewrites the speed control program of the variable frequency injection pump in real time. Since the output pressure of the variable frequency injection pump is approximately proportional to the square of its speed, the actuator drive converts the dynamic differential pressure compensation value into a corresponding speed compensation increment and adds this increment to the original speed setpoint to obtain a new speed control command. The actuator drive sends the new speed control command to the frequency converter of the variable frequency injection pump. The frequency converter adjusts the motor speed according to the command, thereby changing the output pressure of the variable frequency injection pump, ensuring that the pumping pressure can synchronously overcome the current pipeline friction resistance and maintain a stable injection flow rate.

[0026] While adjusting the speed of the variable frequency injection pump, the actuator drive also corrects the pulse width modulation (PWM) duty cycle of the heater based on the deviation in fluid heat absorption rate caused by the speed change. Changes in the pump speed alter the residence time of asphalt in the heating zone, thus affecting the heat absorbed by the asphalt. When the speed increases, the residence time of the asphalt in the heating zone shortens, resulting in less heat absorption and potentially a decrease in asphalt temperature; conversely, when the speed decreases, the residence time of the asphalt in the heating zone lengthens, resulting in more heat absorption and potentially an increase in asphalt temperature. To eliminate the interference of this flow fluctuation on the thermal balance, the actuator drive needs to calculate the fluid heat absorption rate at the current flow rate based on the real-time speed and compare it with the current output power of the heater to adjust the heater's PWM duty cycle.

[0027] Specifically, the fluid heat absorption rate refers to the heat absorbed by the fluid as it passes through the heating zone per unit time, and its specific expression is as follows: (4) Where q is the fluid heat absorption rate, in W; This represents the density of molten asphalt, expressed in kg / m³. ν is the isobaric specific heat capacity of molten asphalt, in J / (kg·K); v is the real-time flow velocity of the asphalt, in m / s; A is the cross-sectional area of ​​the heating zone, in m².

[0028] The residence time of the fluid in the heating zone can be determined by the length of the heating zone. The ratio to the real-time flow velocity v is calculated as follows: During the stay Inside, the heater outputs heat of ,in The current output power of the heater is expressed in watts (W); the heat absorbed by the fluid is... The thermal balance deviation is the difference between the heat output of the heater and the heat absorbed by the fluid, and its specific expression is: (5) in, This represents the thermal balance deviation, expressed in J.

[0029] The actuator drive end is based on the thermal balance deviation The pulse width of the heater's pulse width modulation duty cycle is dynamically adjusted. When When the heat output of the heater exceeds the heat absorbed by the fluid, the asphalt temperature tends to rise. The actuator reduces the pulse width modulation duty cycle, thus lowering the heater's output power. When the temperature of the asphalt decreases, it indicates that the heat output by the heater is less than the heat absorbed by the fluid. The actuator then increases the pulse width modulation duty cycle to increase the heater's output power. In this way, the system can maintain a stable asphalt temperature while adjusting the injection flow rate, forming a temperature-flow coordinated closed-loop program control.

[0030] This embodiment deeply binds the thermodynamic state parameters of asphalt with the flow control parameters through a heat-flow coupling compensation calculation core, achieving coordinated operation of temperature and flow control. When asphalt loses heat upon contact with the cold pavement wall, leading to an increase in dynamic viscosity, the system can calculate the required differential pressure compensation value in real time and adjust the speed of the variable frequency injection pump to ensure that the pumping pressure synchronously overcomes the increased frictional resistance and avoids attenuation of the injection flow rate. Simultaneously, the system can adjust the heater's output power according to changes in speed, eliminating the interference of flow fluctuations on thermal balance and maintaining stable asphalt temperature.

[0031] In a preferred embodiment, reference Figure 2The multi-source sensing acquisition front end includes a multi-point temperature sensor array and a differential pressure sensor installed within the injection pipeline. The multi-point temperature sensor array is arranged at equal intervals along the pipeline axis, collecting discrete temperature field signals at different locations along the pipeline axis. These discrete temperature field signals reflect the temperature distribution changes of the asphalt during its flow within the pipeline, thus more accurately capturing the heat loss process of the asphalt. The differential pressure sensor is installed at both ends of the injection nozzle, collecting the pressure difference fluctuation signals before and after the nozzle. These pressure difference fluctuation signals directly reflect the changes in resistance within the pipeline and are an important basis for judging the flow state of the pipeline.

[0032] After acquiring discrete temperature field signals, the multi-source sensor acquisition front-end uses a sliding window mean filter to remove thermal noise. The sliding window mean filter has a window size of 5 consecutive sampling points, a sliding step size of 1 sampling point, and a sampling frequency of 100Hz for each sampling point. During the filtering process, the average of the 5 sampled values ​​within the window is calculated as the filtered temperature value at the current moment. This filtering method can effectively remove high-frequency thermal noise from discrete temperature field signals while retaining the trend information of temperature changes, avoiding errors in the extraction of heat dissipation features due to noise interference.

[0033] The multi-source sensor acquisition front-end processes the filtered discrete temperature field signal and extracts the temperature fall-off slope as a heat dissipation characteristic. The temperature fall-off slope reflects the rate at which the asphalt temperature decreases over time and is a key parameter characterizing the rate of heat loss from asphalt. Specifically, the multi-source sensor acquisition front-end identifies the moment when the temperature begins to fall in the discrete temperature field signal, then calculates the rate of temperature change over three consecutive sampling intervals after that moment, and takes the average of these three rates of temperature change as the temperature fall-off slope. When the asphalt contacts the cold wall of the pavement and experiences severe heat loss, the temperature fall-off slope will increase significantly, allowing the system to quickly detect the occurrence of heat loss through this characteristic.

[0034] The multi-source sensor acquisition front end synchronizes and aligns the extracted heat dissipation characteristics with the acquired differential pressure fluctuation signal before sending them to the thermal-fluid coupling compensation calculation core. The synchronization and alignment process is achieved by adding a uniform timestamp to each acquired signal, with a timestamp accuracy of 1ms. When acquiring each temperature and differential pressure sampling point, the multi-source sensor acquisition front end simultaneously records the acquisition time of that sampling point, generating a corresponding timestamp. Upon receiving the heat dissipation characteristics and differential pressure fluctuation signal, the thermal-fluid coupling compensation calculation core aligns the two signals on the time axis according to the timestamps, ensuring that the time bases of the two signals are completely consistent and avoiding subsequent calculation errors caused by signal asynchrony.

[0035] After receiving the synchronized and aligned heat dissipation characteristic quantity and pressure difference fluctuation signal, the heat-flow coupling compensation calculation core calculates the rate of change of the heat dissipation characteristic quantity and the phase difference between the pressure difference fluctuation signal. The rate of change of the heat dissipation characteristic quantity is obtained by performing a first-order difference calculation on the heat dissipation characteristic quantity, reflecting the speed of change of the heat dissipation rate. The phase difference refers to the time difference between the peak moment of the rate of change of the heat dissipation characteristic quantity and the peak moment of the pressure difference fluctuation signal. Under normal flow conditions, the change of the heat dissipation characteristic quantity and the change of the pressure difference fluctuation signal are basically synchronized, and the phase difference is small. When a local solidification blockage occurs in the injection pipeline, the flow resistance of the asphalt will suddenly increase, causing the peak moment of the pressure difference fluctuation signal to lag behind the peak moment of the rate of change of the heat dissipation characteristic quantity, and the phase difference will increase.

[0036] The thermal-fluid coupling compensation calculation core compares the calculated phase difference with a preset hysteresis threshold. When the phase difference exceeds the preset hysteresis threshold, a local solidification blockage is determined to have occurred in the injection pipeline. The preset hysteresis threshold is pre-set based on factors such as pipeline length, asphalt grade, and operating temperature, and is generally set to 50ms to 100ms. When a local solidification blockage is determined to have occurred, the thermal-fluid coupling compensation calculation core generates a pulse backflush command and sends it to the actuator drive end.

[0037] After receiving the pulse backflush command, the actuator drive controls the variable frequency injection pump to instantly reverse and then resume forward rotation, using transient reverse pressure to peel off the initially set asphalt in a locally solidified and blocked state. The pulse backflush command includes three parameters: reverse rotation speed, reverse rotation duration, and forward rotation recovery speed. Different phase difference ranges correspond to different pulse backflush parameters, and the specific parameter settings are shown in Table 1.

[0038] Table 1. Pulse Recoil Command Parameter Setting Table

[0039] According to the parameters in the pulse backflush command, the actuator drive first rapidly adjusts the speed of the variable frequency injection pump from the original forward speed to the reverse speed, maintains the reverse speed for a certain duration, and then rapidly adjusts the speed back to the original forward speed. During the reverse process, the fluid in the pipeline generates transient reverse pressure. This reverse pressure can impact the initially hardened asphalt on the inner wall of the pipeline, causing it to peel off from the pipe wall and flow with the fluid, thereby eliminating local solidification blockage and restoring the normal flow state of the pipeline.

[0040] This embodiment acquires discrete temperature field signals using a multi-point temperature sensor array and extracts the slope of the temperature drop edge as a heat loss characteristic, improving the sensitivity and accuracy of heat loss detection. By synchronizing the heat loss characteristic with the differential pressure fluctuation signal, the temporal consistency of the two signals is ensured. The phase difference between the two signals is calculated to determine the local solidification blockage state, and a pulse backflush command is generated to control the variable frequency injection pump to perform a backflush action, effectively eliminating local solidification blockage in the pipeline and preventing injection interruption.

[0041] In a preferred embodiment, reference Figure 3 The thermal-fluid coupling compensation calculation core incorporates a viscosity-temperature characteristic equation that is dynamically updated according to the aging degree of asphalt. During heating, asphalt undergoes thermal degradation, leading to changes in its molecular structure and thus altering its viscosity-temperature characteristics. As heating time and temperature increase, the aging degree of asphalt gradually deepens, and its dynamic viscosity gradually increases at the same temperature. Using a fixed standard viscosity-temperature characteristic equation for dynamic viscosity inversion can cause discrepancies between the inversion results and actual values, affecting the accuracy of differential pressure compensation. Therefore, the viscosity-temperature characteristic equation needs to be dynamically corrected based on the real-time aging degree of the asphalt.

[0042] The core of the heat-fluid coupling compensation calculation extracts the cumulative heating time and historical peak temperature to calculate the asphalt aging index. The cumulative heating time refers to the total time from the start of asphalt heating to the current moment, and the historical peak temperature refers to the highest temperature reached by the asphalt within the cumulative heating time. The asphalt aging index is a comprehensive parameter characterizing the degree of asphalt aging, and its specific expression is: (6) in, The asphalt aging index is dimensionless. The coefficient representing the influence of heating time is dimensionless. The total heating time is expressed in hours (h). The peak temperature influence coefficient is dimensionless. The historical peak temperature is expressed in °C. and The value is determined in advance through experiments based on the grade of asphalt. The value range is from 0.001 to 0.01. The value range is from 0.01 to 0.1.

[0043] The core of the heat-fluid coupling compensation calculation uses the calculated asphalt aging index to reduce the order of the exponential term coefficients in the standard viscosity-temperature characteristic equation, thus obtaining the real-time viscosity-temperature characteristic equation. For the viscosity-temperature index of unaged asphalt, after order reduction correction, the expression for the real-time viscosity-temperature index B is: ,in The reduction-order correction coefficient is dimensionless. Substituting the corrected real-time viscosity-temperature index B into formula (1) yields the real-time viscosity-temperature characteristic equation considering the thermal degradation effect. The thermal-fluid coupling compensation calculation core uses this real-time viscosity-temperature characteristic equation to map the real-time temperature signal into a dynamic viscosity parameter, thereby improving the accuracy of the dynamic viscosity parameter inversion.

[0044] Furthermore, the heat-fluid coupling compensation calculation core incorporates the extreme value envelope of the real-time temperature signal for integration when calculating the asphalt aging index, obtaining the cumulative heat load value. The cumulative heat load value more comprehensively reflects the total amount of heat exerted on the asphalt during the heating process, and more accurately characterizes the degree of asphalt aging than simply the cumulative heating time and historical peak temperature. The specific expression for the cumulative heat load value is as follows: (7) Where H is the cumulative heat load value, in °C·h; for The temperature of the asphalt at any given time, in °C; This refers to the ambient temperature, expressed in °C. The current time is expressed in hours (h). The integration operation is performed using the trapezoidal numerical integration method, which multiplies the temperature difference within each sampling interval by the sampling interval and then sums them to obtain the cumulative heat load value.

[0045] The core of the heat-fluid coupling compensation calculation substitutes the calculated cumulative heat load value into a piecewise linear function containing the critical heat load boundary to determine the value of the order reduction correction coefficient k. The aging process of asphalt consists of two stages: when the cumulative heat load value is less than the critical heat load... At that time, the aging rate of asphalt is relatively slow, and the reduction correction factor is relatively small; when the cumulative heat load value is greater than or equal to the critical heat load... As the asphalt ages faster, the reduction-order correction factor increases. The specific form of the piecewise linear function is: (8) in, These are the first-stage order reduction correction coefficients. These are the second-stage order reduction correction coefficients. ; This is the critical heat load value, expressed in °C·h. , and The value of is determined in advance through experiments based on the grade of asphalt. The parameter settings for different grades of asphalt are shown in Table 2.

[0046] Table 2. Aging Correction Parameters for Different Asphalt Grades

[0047] When the cumulative heat load value crosses the critical heat load boundary, the reduction correction factor will change from... Suddenly switched This leads to a step jump in the real-time viscosity-temperature index B, which in turn causes a step jump in the dynamic viscosity parameter, potentially causing oscillations and shocks to the control system. To eliminate this step jump, the thermal-fluid coupling compensation calculation core uses Lagrange interpolation to smoothly transition the step jump in the dynamic viscosity parameter caused by the slope coefficient switching in the real-time viscosity-temperature characteristic equation.

[0048] Specifically, the core of the heat-fluid coupling compensation calculation is when the cumulative heat load value is at arrive Within the transition interval, the intermediate value of the order reduction correction coefficient k is calculated using linear Lagrange interpolation. The width of the transition interval... The value is typically taken to be between 5℃·h and 10℃·h. Within the transition range, the expression for the order reduction correction coefficient k is: Using this interpolation method, the order reduction correction coefficient k changes from [previous value] to [current value] within the transition interval. linear transition to This results in the real-time viscosity-temperature index B and the dynamic viscosity parameter. It also achieves a smooth transition, avoiding the impact of step transitions on the control system.

[0049] This embodiment introduces an asphalt aging index to dynamically correct the viscosity-temperature characteristic equation, considering the impact of asphalt thermal degradation on dynamic viscosity and improving the accuracy of dynamic viscosity parameter inversion. By calculating the cumulative heat load value and using a piecewise linear function to determine the order reduction correction coefficient, the viscosity-temperature characteristics of asphalt at different aging stages can be more accurately reflected. The Lagrange interpolation method is used to smoothly transition the order reduction correction coefficient switching process, eliminating abrupt changes in dynamic viscosity parameters and ensuring the stability of the control system.

[0050] In a preferred embodiment, reference Figure 4 The core of the heat-fluid coupling compensation calculation performs high-pass filtering on the flow velocity signal to extract high-frequency pulsation components before calculating the theoretical friction loss. During asphalt grouting, air or gases produced by the thermal decomposition of asphalt may mix into the pipeline, forming gas-phase inclusions. These gas-phase inclusions increase the compressibility of the fluid. When the pipeline pressure changes, the gas phase will compress or expand, causing high-frequency pulsations in the flow velocity signal. These high-frequency pulsations interfere with the calculation of the theoretical friction loss, leading to errors in the dynamic pressure difference compensation value. Therefore, it is necessary to perform high-pass filtering on the flow velocity signal to extract the high-frequency pulsation components for calculating the gas resistance compensation coefficient.

[0051] The high-pass filter has a cutoff frequency of 10Hz, effectively removing low-frequency flow components from the flow velocity signal while retaining high-frequency pulsation components above 10Hz. The filtering process uses a Butterworth high-pass filter with a fourth-order configuration, maintaining a flat amplitude-frequency response in the passband and exhibiting rapid attenuation in the stopband. The thermal-fluid coupling compensation core processes the filtered high-frequency pulsation components, calculating their root mean square (RMS) value, which serves as the amplitude of the high-frequency pulsation component. .

[0052] The core of the thermal-fluid coupling compensation calculation is based on the amplitude of the high-frequency pulsation component. Calculate the air resistance compensation coefficient The air resistance compensation coefficient is used to correct the theoretical pressure drop along the pressure path and eliminate the interference of gas-phase compression on the calculation of the pressure difference compensation value. The specific expression for the air resistance compensation coefficient is: (9) in, This is the air resistance compensation coefficient, which is dimensionless. The proportionality constant is dimensionless. This represents the amplitude of the high-frequency pulsation component, expressed in m / s. The value of is determined experimentally in advance based on the inner diameter of the pipeline and the viscosity of the asphalt, and the range is from 0.001 to 0.01. The larger the amplitude of the high-frequency pulsation component, the higher the degree of gas phase inclusion in the pipeline, the smaller the gas resistance compensation coefficient, and the smaller the corrected theoretical pressure drop along the pipeline.

[0053] The thermal-fluid coupling compensation calculation core multiplies the calculated air resistance compensation coefficient by the theoretical pressure drop along the friction path to obtain the corrected theoretical pressure drop. The expression for the corrected theoretical pressure drop along the friction path is as follows: ,in This is the corrected theoretical pressure drop along the pressure path, in Pa.

[0054] The core of the thermal-fluid coupling compensation calculation calculates the difference between the corrected theoretical friction drop and the reference pressure drop, and outputs this difference as the dynamic differential pressure compensation value to the actuator drive end. By introducing a gas resistance compensation coefficient to correct the theoretical friction drop, the interference of gas phase inclusions in the pipeline on the calculation of the differential pressure compensation value can be effectively eliminated, improving the accuracy of the dynamic differential pressure compensation value, thereby ensuring that the output pressure of the variable frequency injection pump can accurately match the actual pipeline resistance.

[0055] This embodiment uses high-pass filtering to extract high-frequency pulsation components from the flow velocity signal, enabling accurate detection of the degree of gas phase inclusion in the pipeline. By calculating the gas resistance compensation coefficient to correct the theoretical pressure drop along the pipeline, the interference of gas phase compression on the calculation of differential pressure compensation value is eliminated, improving the accuracy of differential pressure compensation and ensuring the stability of the injection flow rate.

[0056] In a preferred embodiment, the actuator drive converts the dynamic differential pressure compensation value into a speed compensation increment for the variable frequency injection pump and adds it to the original speed setting. The output pressure of the variable frequency injection pump is approximately proportional to the square of the speed; therefore, the speed compensation increment and the dynamic differential pressure compensation value are related as follows: ,in This is the speed compensation increment, in r / min; The original speed setting is given in r / min. The actuator drive calculates the speed compensation increment according to the above formula and adds it to the original speed setting to obtain the real-time speed. .

[0057] The actuator drive sends a new speed control command to the frequency converter of the variable frequency injection pump, which adjusts the motor speed according to the command. The frequency converter uses vector control, enabling precise adjustment of the motor speed, with an accuracy of ±1 r / min. In this way, the output pressure of the variable frequency injection pump can be adjusted in real time according to the dynamic differential pressure compensation value, allowing the pumping pressure to synchronously overcome the current pipeline friction resistance and maintain a stable injection flow rate.

[0058] The actuator drive calculates the fluid heat absorption rate at the current flow rate based on the real-time rotational speed of the variable frequency injection pump, and determines the heat balance deviation by comparing the fluid heat absorption rate with the current output power of the heater. The pulse width of the pulse width modulation duty cycle is then dynamically adjusted based on this heat balance deviation. There is a linear relationship between the real-time rotational speed and the real-time flow rate; the real-time flow rate v can be obtained by considering the real-time rotational speed n and the pump's displacement coefficient. The product is calculated as follows: Displacement coefficient It is a constant related to the structural parameters of the pump, which is determined experimentally in advance. The actuator drive end substitutes the calculated real-time flow rate into formula (4) to obtain the fluid heat absorption rate q at the current flow rate. Then, the actuator drive end calculates the residence time of the fluid in the heating zone. Substituting this into formula (5), we obtain the thermal balance deviation. .

[0059] The actuator drive end is based on the thermal balance deviation The pulse width modulation (PWM) duty cycle of the heater is dynamically adjusted using a proportional control method. The period of the PWM signal is fixed at 100ms, and the duty cycle adjustment range is 0% to 100%. The duty cycle adjustment amount... With thermal balance deviation The relationship between them is ,in This is the proportional adjustment coefficient, with units of % / J. The value is determined in advance through experiments based on the power of the heater and the heat capacity of the heating zone, and the value ranges from 0.001% / J to 0.01% / J.

[0060] when Duty cycle adjustment amount When positive, the actuator drive increases the pulse width modulation duty cycle, thereby increasing the heater's output power; when... Duty cycle adjustment amount When the value is negative, the actuator reduces the pulse width modulation duty cycle, thereby lowering the heater's output power. Through this proportional adjustment method, the heater's output power can be adjusted in real time according to changes in the fluid's heat absorption rate, maintaining thermal balance and preventing asphalt temperature fluctuations caused by flow rate changes.

[0061] This embodiment achieves precise adjustment of the variable frequency injection pump speed by converting the dynamic differential pressure compensation value into a speed compensation increment and adding it to the original speed setting value. By calculating the fluid heat absorption rate based on the real-time speed and adjusting the pulse width modulation duty cycle of the heater, the interference of flow rate changes on the thermal balance can be eliminated, the asphalt temperature can be kept stable, and the injection quality can be guaranteed.

[0062] In a preferred embodiment, reference Figure 5 The multi-source sensor acquisition front end also acquires ambient temperature and road surface temperature. Ambient temperature is acquired through a temperature sensor located outside the grouting equipment, while road surface temperature is acquired through a non-contact temperature sensor located at the front end of the grouting equipment. Ambient temperature and road surface temperature are important factors affecting heat exchange during the asphalt grouting process. During the cold start phase, the lower the ambient temperature and road surface temperature, the more intense the heat exchange between the asphalt and the outside environment, and the higher the initial heating power and initial pumping back pressure required.

[0063] The core of the heat-fluid coupling compensation calculation calculates the average thermal radiation potential of the ambient temperature and the pavement temperature before starting the grouting program. The average thermal radiation potential is a comprehensive parameter characterizing the thermal effects of the environment and the pavement on asphalt. It is calculated as the arithmetic mean of the ambient temperature and the pavement temperature. ,in The average thermal radiation potential is expressed in °C.

[0064] The core of the heat-fluid coupling compensation calculation uses the difference between the calculated average thermal radiation potential and the target injection temperature to retrieve the initial heating power setpoint and the initial pumping back pressure value from a pre-stored initial power matching table. The initial power matching table is determined through a pre-conducted cold start experiment and lists the initial heating power coefficient and initial pumping back pressure coefficient corresponding to different differences between the average thermal radiation potential and the target injection temperature. The target injection temperature is pre-set based on the asphalt grade and construction requirements, typically ranging from 160℃ to 180℃. The specific contents of the initial power matching table are shown in Table 3.

[0065] Table 3 Initial Power Matching Table

[0066] During the cold start phase, the actuator drive operates according to the initial heating power setpoint and the initial pumping back pressure value. In this phase, the asphalt temperature is low and the dynamic viscosity is high, requiring a high initial heating power to rapidly raise the asphalt temperature. Simultaneously, a high initial pumping back pressure is needed to overcome significant frictional resistance and ensure smooth asphalt flow. The actuator drive controls the heater to operate at the initial heating power and simultaneously controls the variable frequency injection pump to operate at the speed corresponding to the initial pumping back pressure.

[0067] The heat-flow coupling compensation calculation core monitors the real-time temperature signal of the asphalt. When the real-time temperature signal reaches the critical temperature range for phase change, the system switches to temperature-flow coordinated closed-loop program control. The critical temperature range for phase change refers to the temperature range in which asphalt changes from a high-viscosity solid state to a low-viscosity molten state, typically ranging from 120℃ to 140℃. When the asphalt temperature enters the critical temperature range for phase change, its dynamic viscosity decreases significantly, and its flow characteristics improve markedly. At this point, the system switches to temperature-flow coordinated closed-loop program control, enabling precise control of the grouting process.

[0068] This embodiment calculates the average thermal radiation potential by acquiring the ambient temperature and road surface temperature, and obtains the initial heating power and initial pumping back pressure by querying the initial power matching table. This enables the rapid establishment of suitable heating and pumping conditions during the cold start phase, avoiding control blind spots in the early stage of cold start, shortening the cold start time, and improving grouting efficiency.

[0069] In a preferred embodiment, reference Figure 6 The thermal-fluid coupling compensation calculation core monitors the rate of change of the pressure signal in real time. The rate of change of the pressure signal is obtained by performing a first-order differential calculation on the pressure signal, reflecting the speed of pressure change inside the pipeline. During the grouting process, when molten asphalt is injected into the crack, the air inside the crack is expelled, and the pressure gradually increases; when the bottom of the crack is sealed by molten asphalt, the air inside the crack can no longer be expelled, and the pressure rises rapidly, causing the rate of change of the pressure signal to show an inflection point from negative to positive.

[0070] The core of the heat-fluid coupling compensation calculation identifies the inflection point of the pressure signal change rate. When the pressure signal change rate shows an inflection point from negative to positive while the flow velocity signal remains constant, it is determined that the bottom of the crack has been sealed by molten asphalt. A constant flow velocity signal means that the fluctuation range of the flow velocity signal does not exceed ±5% within five consecutive sampling periods before and after the inflection point. By simultaneously monitoring the inflection point of the pressure signal change rate and the stability of the flow velocity signal, the sealing status at the bottom of the crack can be accurately determined, avoiding misjudgments.

[0071] The core of the heat-fluid coupling compensation calculation calculates the actual volume of the current crack based on the cumulative injection flow rate at the time of the inflection point. The cumulative injection flow rate refers to the total volume of asphalt injected into the crack through the injection nozzle from the start of injection to the time of the inflection point. The cumulative injection flow rate can be obtained by integrating the real-time flow velocity signal; the specific expression is as follows: ,in The actual volume of the crack. The unit for the inflection point is m³; A is the cross-sectional area of ​​the injection nozzle, in m². The value represents the moment when the inflection point occurs, expressed in seconds. Integration is performed using the trapezoidal rule for numerical integration.

[0072] The core of the thermal-fluid coupling compensation calculation adjusts the step distance of subsequent grouting strokes based on the ratio of the actual volume to the preset calibration volume. The preset calibration volume refers to the volume of a standard crack, which is set in advance according to construction specifications. The method for correcting the step distance of subsequent grouting strokes is as follows: ,in The corrected step distance is in meters. This is the original step distance, in meters. This is the preset calibration volume, in m³. By adjusting the step distance of subsequent grouting strokes, the grouting length can be adjusted according to the actual size of the crack, avoiding under-grouting or over-grouting.

[0073] Simultaneously, the actuator drive switches the speed control program of the variable frequency injection pump to the pressure-holding and retarding mode. The parameters of the pressure-holding and retarding mode are determined based on the ratio of the actual crack volume to the preset calibration volume, and the specific parameter settings are shown in Table 4.

[0074] Table 4 Parameters for Pressure Holding and Retarding Mode

[0075] In the pressure-holding and retarding mode, the actuator drive controls the variable frequency injection pump to maintain a certain pressure, allowing the asphalt to fully fill the tiny gaps in the crack and improve the injection quality. Simultaneously, the actuator drive reduces the speed of the variable frequency injection pump to prevent asphalt from overflowing onto the crack surface. After the pressure-holding time ends, the actuator drive stops the variable frequency injection pump, completing the injection operation for that crack.

[0076] This embodiment determines the sealing status at the bottom of the crack by monitoring the inflection point of the pressure signal change rate, thus accurately identifying the grouting endpoint. By calculating the actual volume of the crack and correcting the step distance of subsequent grouting strokes, adaptive grouting for cracks of different sizes can be achieved. By switching to a pressure-holding and retarding mode, it ensures that the asphalt fully fills the crack, improving grouting quality.

Claims

1. An industrial control system for the asphalt pavement crack grouting process, characterized in that, This includes a multi-source sensor acquisition front-end, a thermal-fluid coupling compensation computing core, and an actuator drive end; The multi-source sensor acquisition front end acquires real-time temperature, pressure and flow rate signals of the asphalt at the injection nozzle; The core of the thermal-fluid coupling compensation calculation is based on the viscosity-temperature characteristic equation of asphalt non-Newtonian fluid to invert the real-time temperature signal into dynamic viscosity parameters, and inputs the dynamic viscosity parameters and the flow velocity signal into the preset resistance compensation model to calculate the dynamic pressure difference compensation value. The actuator drive end rewrites the speed control program of the variable frequency injection pump in real time according to the dynamic differential pressure compensation value, and corrects the pulse width modulation duty cycle of the heater based on the fluid heat absorption rate deviation caused by the speed change, forming a temperature-flow coordinated closed-loop program control.

2. The industrial control system for the asphalt pavement crack melting and grouting process according to claim 1, characterized in that, The multi-source sensing acquisition front end includes a multi-point temperature sensor array and a differential pressure sensor disposed in the infusion pipeline; The multi-point temperature sensor array collects discrete temperature field signals distributed axially in the pipeline, and the differential pressure sensor collects differential pressure fluctuation signals before and after the nozzle. The multi-source sensing acquisition front end removes thermal noise from the discrete temperature field signal by means filtering through a sliding window, extracts the temperature drop slope as a heat dissipation characteristic, and synchronously aligns the heat dissipation characteristic with the pressure difference fluctuation signal to the heat-flow coupling compensation calculation core.

3. The industrial control system for the asphalt pavement crack melting and grouting process according to claim 1, characterized in that, The heat-fluid coupling compensation calculation core is embedded with a viscosity-temperature characteristic equation that is dynamically updated with the aging degree of asphalt. The heat-fluid coupling compensation calculation core extracts the cumulative heating time and historical peak temperature, calculates the asphalt aging index, and uses the asphalt aging index to reduce the order of the coefficient of the exponential term in the standard viscosity-temperature characteristic equation to obtain the real-time viscosity-temperature characteristic equation. The real-time viscosity-temperature characteristic equation maps the real-time temperature signal to the dynamic viscosity parameter that takes into account the thermal degradation effect.

4. The industrial control system for the asphalt pavement crack melting and grouting process according to claim 1, characterized in that, The resistance compensation model constructs a correlation mapping between the dynamic viscosity parameter and the pipe friction loss. The heat-fluid coupling compensation calculation core inputs the dynamic viscosity parameter and the flow velocity signal into the resistance compensation model, calculates the theoretical friction loss under the current viscosity and flow velocity according to the Hagen-Poiseuille equation, and calculates the difference between the theoretical friction loss and the reference pressure loss. The difference is then used as the dynamic differential pressure compensation value and output to the actuator drive end.

5. The industrial control system for the asphalt pavement crack melting and grouting process according to claim 1, characterized in that, The actuator drive end converts the dynamic differential pressure compensation value into the speed compensation increment of the variable frequency injection pump and adds it to the original speed setting value; The actuator drive end calculates the fluid heat absorption rate at the current flow rate based on the real-time rotation speed of the variable frequency injection pump, and calculates the heat balance deviation between the fluid heat absorption rate and the current output power of the heater. Based on the heat balance deviation, the pulse width of the pulse width modulation duty cycle is dynamically adjusted to compensate for the heat deviation caused by the change in the residence time of the fluid in the heating zone due to the change in rotation speed.

6. The industrial control system for the asphalt pavement crack melting and grouting process according to claim 2, characterized in that, After receiving the heat dissipation characteristic quantity and the pressure difference fluctuation signal, the heat-fluid coupling compensation calculation core calculates the rate of change of the heat dissipation characteristic quantity and the phase difference of the pressure difference fluctuation signal. When the phase difference exceeds the preset hysteresis threshold, it is determined that a local solidification blockage has occurred in the infusion pipeline; The thermal-fluid coupling compensation calculation core generates a pulse backflush command and sends it to the actuator drive end. The actuator drive end controls the variable frequency injection pump to instantly reverse and resume forward rotation, using transient reverse pressure impact to peel off the initial set asphalt in the local solidification blockage state.

7. The industrial control system for the asphalt pavement crack grouting process according to claim 3, characterized in that, The heat-fluid coupling compensation calculation core incorporates the extreme envelope of the real-time temperature signal for integration calculation when calculating the asphalt aging index to obtain the cumulative heat load value. The heat-fluid coupling compensation calculation core substitutes the cumulative heat load value into a piecewise linear function containing the critical heat load boundary. When the cumulative heat load value crosses the critical heat load boundary, the slope coefficient of the order reduction correction is switched, and the step change of the dynamic viscosity parameter caused by the switch of the slope coefficient in the real-time viscosity-temperature characteristic equation is smoothly transitioned by the Lagrange interpolation method.

8. The industrial control system for the asphalt pavement crack melting and grouting process according to claim 4, characterized in that, Before calculating the theoretical friction loss, the thermal-fluid coupling compensation calculation core performs high-pass filtering on the flow velocity signal to extract high-frequency pulsation components. The high-frequency pulsation component characterizes the degree of gas phase entrainment within the infusion pipeline; The heat-fluid coupling compensation calculation core calculates the air resistance compensation coefficient based on the amplitude of the high-frequency pulsation component, and multiplies the air resistance compensation coefficient by the theoretical friction drop to obtain the corrected theoretical friction drop.

9. The industrial control system for the asphalt pavement crack melting and grouting process according to claim 1, characterized in that, The multi-source sensor acquisition front end also acquires ambient temperature and road surface temperature; Before starting the grouting program, the thermal-fluid coupling compensation calculation core calculates the average thermal radiation potential of the ambient temperature and the road surface temperature, and obtains the initial heating power setting value and the initial pumping back pressure value by querying the pre-stored initial power matching table based on the difference between the average thermal radiation potential and the target grouting temperature. During the cold start phase, the actuator drive operates according to the initial heating power setting value and the initial pumping back pressure value until the real-time temperature signal reaches the critical temperature range of phase change, after which it switches to the temperature-flow coordinated closed-loop program control.

10. The industrial control system for the asphalt pavement crack melting and grouting process according to claim 1, characterized in that, The thermal-fluid coupling compensation calculation core monitors the rate of change of the pressure signal in real time. When the rate of change of the pressure signal reaches an inflection point from negative to positive and the flow velocity signal remains unchanged, it is determined that the bottom of the crack has been sealed by molten asphalt. The heat-fluid coupling compensation calculation core calculates the actual volume of the current crack based on the cumulative injection flow rate when the inflection point occurs, and corrects the step distance of the subsequent injection stroke based on the ratio of the actual volume to the preset calibration volume. At the same time, the actuator drive end switches the speed control program of the variable frequency injection pump to the pressure holding and slowing mode.

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