A pickling line monitoring system

Abstract

The application provides a pickling line monitoring system, comprising a sensor, a control module and an actuator, the sensor monitors the acid concentration, temperature, liquid level and driving speed of the pickling line, the actuator is used for controlling the pickling tank to add acid, dilute acid, discharge acid, heat and circulate, the control module controls the actuator in real time according to the sensor data to maintain the acid concentration in the pickling tank near the optimal value of the pickling process, the real-time control strategy of the control module comprises an integrated compound control strategy of feedforward control and PID feedback control, the feedforward control improves the feedforward compensation according to the change of the driving speed of the pickling line, and the PID feedback control sets a dead zone to reduce the disturbance of the acid concentration, temperature and liquid level data on the output. The application improves the adjustment precision and automatic degree of the acid concentration of the pickling line.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of metal processing, and particularly relates to an acid pickling line monitoring system. BACKGROUND

[0002] In the steel and metal product processing industry, the acid pickling line is a crucial surface treatment process, which removes the oxide layer on the surface of the steel through acid liquor, directly affecting the final quality of the product. At present, most acid pickling lines still use a control system based on traditional PID feedback, which adjusts according to sensor data such as acid concentration and temperature. However, such systems have obvious limitations: on the one hand, they are difficult to respond to the severe disturbance caused by changes in the driving speed of the acid pickling line, resulting in a lag in concentration control; on the other hand, sensor measurement noise and small fluctuations easily cause the actuator to act frequently, not only accelerating equipment wear and tear, but also reducing the stability and control accuracy of the system. In addition, the existing system still has a lot of room for improvement in terms of anti-interference ability and set value tracking performance under dynamic conditions. SUMMARY

[0003] Therefore, the present application aims to provide an acid pickling line monitoring system to improve the acid concentration adjustment accuracy and automation of the acid pickling line.

[0004] To achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0005] An acid pickling line monitoring system.

[0006] Further, the system comprises a sensor, a control module, and an actuator. The sensor monitors the acid concentration, temperature, liquid level, and driving speed of the acid pickling line. The actuator is used to control the acid pickling tank's acid supplement, acid dilution, acid discharge, heating, and circulation process actions. The control module controls the actuator in real time based on sensor data to maintain the acid concentration in the acid pickling tank near the optimal value of the pickling process.

[0007] The real-time control strategy of the control module includes using a feedforward control and PID feedback control integrated control strategy to adjust the output parameters of the actuator in real time. The feedforward control improves the feedforward compensation for changes in the driving speed of the acid pickling line, and the PID feedback control sets a dead zone to reduce the disturbance of acid concentration, temperature, and liquid level data on the output.

[0008] Further, the sensor comprises an acid concentration sensor for monitoring the acid concentration value of the acid pickling tank and transmitting it to the control module through a 4-20mA analog signal.

[0009] A temperature sensor for monitoring the real-time temperature of the acid liquor in the acid pickling tank and transmitting it to the control module through a signal conversion module.

[0010] A liquid level sensor for monitoring the liquid level and total acid amount of the acid pickling tank and transmitting it to the control module through a 4-20mA analog signal.

[0011] The encoder is used to measure the speed of the pickling line drive and transmits the real-time speed to the control module via high-speed pulse signals or fieldbus protocols.

[0012] Furthermore, the actuator includes: several regulating valves for replenishing acid to the pickling tank and diluting acid, the opening degree of which is controlled by the control module with analog output signals;

[0013] The on / off valve is used to drain acid from the pickling tank, and its opening and closing are controlled by the control module through a switching signal.

[0014] The heater is used to heat the acid solution in the pickling tank. The heating power of the heater is controlled in real time by the control module using an analog output signal.

[0015] The circulating pump is used to circulate the acid solution in the pickling tank, and its start and stop are controlled by the control module through a switch signal.

[0016] Furthermore, the composite control strategy of the control module includes:

[0017] When the pickling tank level falls below the threshold, the processor module activates a safety interlock to stop all outputs to the actuators and close all valves.

[0018] When the monitoring system is in manual mode, all outputs of the control module to the actuator are directly set by the operator.

[0019] When the monitoring system is in automatic mode, the control module determines whether the last program polling mode was manual mode. If so, it retains the PID feedback control parameters from the last manual mode and enables feedforward control. Otherwise, it adjusts the PID feedback control parameters in real time based on sensor data and enables feedforward control.

[0020] Furthermore, the composite control strategy formula of the control module is as follows:

[0021] ;

[0022] ;

[0023] ;

[0024] In the formula, To adjust the target opening of the acid replenishment regulating valve, For feedforward control output, For PID feedback control output, This is the gain coefficient. This refers to the real-time linear speed of the pickling line drive. This is the baseline speed for the pickling line drive. The reference opening degree for adjusting the acid replenishment valve; For the proportion term, For integration, For differential terms, This represents the target acid concentration after dead zone treatment. For the effective error integral, To suppress the overshoot rate of change in acid concentration.

[0025] Furthermore, the control module performs logic calculations and control through an MCU, and the MCU control content includes:

[0026] The composite control strategy calculation is based on the acid concentration value, acid temperature value, liquid level height value, and transmission speed value fed back by the system, combined with the manually set acid concentration set value, temperature set value, and upper and lower limits of liquid level. It calculates and outputs in real time the opening degree of the acid replenishment regulating valve, the opening degree of the acid dilution regulating valve, the regulating power of the heater, and the closed state of the acid discharge switch valve.

[0027] Automatic mode switching judgment: When the system switches from automatic to manual, the integral term of the PID controller is initialized according to the current PID feedback control parameters, the PID feedback control parameters of the last polled mode, and the actual valve position of the previous manual operation, so that the controller outputs a continuous and smooth value before and after the switch. Conversely, when the system switches from manual to automatic, the integral term of the PID controller is initialized according to the actual valve position of the current manual operation, the PID feedback control parameters of the current automatic mode, and the PID feedback control parameters of the last polled mode, so that the controller outputs a continuous and smooth value before and after the switch. The last polled manual / automatic control state is stored to prepare for the next manual / automatic switching action.

[0028] Furthermore, the control module MCU packages the input variables, output variables, set values, and parameter values ​​into a structure according to their sequential addresses. The main function parses and reads and writes the structure to achieve high real-time performance and high refresh rate response to the composite control strategy.

[0029] The control module MCU uses interrupt service functions to perform composite control strategy calculations and automatic mode switching judgments, and uses the main function to switch working states including updating set values, recording data, status monitoring, and low power management.

[0030] Furthermore, the control module MCU establishes input buffers for each sensor and output buffers for each actuator. The original sensor data is stored in the sensor input buffer. The interrupt service function calculates the actuator output parameters and stores them in the actuator output buffer. The buffer is called in the main function to output the actuator control parameters, thereby eliminating the race condition between the interrupt service function and the main function.

[0031] Compared with the prior art, the pickling line monitoring system of the present invention has the following advantages:

[0032] (1) The monitoring system described in this invention consists of a closed-loop control system composed of a sensor, a control module and an actuator. The sensor monitors multiple parameters such as acid concentration, temperature, liquid level and steel belt transmission speed in real time. The control module adopts a composite strategy combining feedforward control and PID feedback control. Feedforward control compensates for acid consumption in advance according to the change in transmission speed. PID control suppresses measurement fluctuation interference through dead zone algorithm. Finally, by precisely adjusting the actuators such as acid replenishment valve, dilution valve and acid discharge valve, the acid concentration is dynamically stabilized in the optimal range of the process, thereby improving the quality and automation of the pickling process.

[0033] (2) The monitoring system described in this invention encapsulates all input, output and set value data into a structure. When passing parameters to a function, only a structure pointer needs to be passed, which reduces the use of stack space and the time overhead of parameter passing. Furthermore, when modifying the sensor-related code, it will not accidentally affect the actuator or other parts.

[0034] (3) The monitoring system described in this invention establishes a double buffering mechanism of input buffer and output buffer to eliminate the race condition between the interrupt service function and the main function. The interrupt service function only writes the sampled data, and the main function only reads the current data, thus avoiding data corruption or inconsistency caused by reading and writing a variable at the same time.

[0035] (4) The monitoring system described in this invention has an interrupt service function that can perform a seamless switching between manual and automatic modes. At the moment of switching from manual mode to automatic mode, the integral term of the PID controller is initialized with the actual valve position of the current manual operation, ensuring that the output value of the controller is consistent before and after the switch and that no sudden control signal is generated, thereby avoiding the impact on the pickling line. Attached Figure Description

[0036] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0037] Figure 1 This is a schematic diagram of the electrical topology of the monitoring system according to an embodiment of the present invention;

[0038] Figure 2 This is a schematic diagram of the monitoring process described in an embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram illustrating the monitoring principle described in an embodiment of the present invention.

[0040] Explanation of reference numerals in the attached figures: Detailed Implementation

[0041] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0042] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0043] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0044] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0045] A pickling line monitoring system, such as Figure 1 The system includes sensors, a control module, and actuators. The sensors monitor the acid concentration, temperature, level, and conveyor speed (i.e., the speed of the steel belt) of the pickling tank. The actuators control the acid replenishment, dilution, discharge, heating, and circulation processes in the pickling tank. The control module controls the actuators in real time based on the sensor data to maintain the acid concentration in the pickling tank near the optimal value for the pickling process. The real-time control strategy of the control module includes using a composite control strategy integrating feedforward control and PID feedback control to adjust the output parameters of the actuators in real time. Feedforward control improves feedforward compensation for changes in the conveyor speed of the pickling line, and PID feedback control sets a dead zone to reduce the disturbance of acid concentration, temperature, and level data on the output.

[0046] Specifically, the sensors include: an acid concentration sensor, used to monitor the acid concentration in the pickling tank and transmit it to the control module via a 4-20mA analog signal; a temperature sensor, used to monitor the real-time temperature of the acid solution in the pickling tank and transmit it to the control module via a signal conversion module; a level sensor, used to monitor the level and total acid volume in the pickling tank and transmit it to the control module via a 4-20mA analog signal; and an encoder, used to measure the speed of the pickling line drive and transmit the real-time speed to the control module via a high-speed pulse signal or fieldbus protocol. The actuators include: several regulating valves, used to replenish and dilute acid in the pickling tank, with the control module controlling their opening degree via analog output signals; switching valves, used to discharge acid from the pickling tank, with the control module controlling their opening and closing via switching signals; a heater, used to heat the acid solution in the pickling tank, with the control module controlling the heater's heating power in real-time via analog output signals; and a circulating pump, used to circulate the acid solution in the pickling tank, with the control module controlling its start and stop via switching signals.

[0047] Furthermore, such as Figure 2 The composite control strategy of the control module shown includes:

[0048] When the pickling tank level is below the threshold, the processor module activates a safety interlock to stop all outputs to the actuators and closes all valves. When the monitoring system is in manual mode, all outputs to the actuators by the control module are directly set by the operator. When the monitoring system is in automatic mode, the control module determines whether the last program polling mode was manual. If so, it retains the PID feedback control parameters from the last manual mode and enables feedforward control. Otherwise, it adjusts the PID feedback control parameters in real time based on sensor data and enables feedforward control.

[0049] The formula for the composite control strategy of the control module:

[0050] ;

[0051] ;

[0052] ;

[0053] In the formula, To adjust the target opening of the acid replenishment regulating valve, For feedforward control output, For PID feedback control output, This is the gain coefficient. This refers to the real-time linear speed of the pickling line drive. This is the baseline speed for the pickling line drive. The reference opening degree for adjusting the acid replenishment valve; For the proportion term, For integration, For differential terms, This represents the target acid concentration after dead zone treatment. The effective error integral; To suppress the rate of change of acid concentration due to overshoot, the derivative of the measured value only focuses on the rate of change of the feedback value. Sudden changes in the set value will not affect the instantaneous rate of change of the feedback value. Therefore, the output change is smooth, which improves the stability of the system and the user experience.

[0054] in, Dead zone processing is required:

[0055] ;

[0056] ;

[0057] ;

[0058] Set the acid concentration value. This refers to the actual acid concentration value returned by the concentration sensor. The dead zone range, introduced for PID input, has the advantage of preventing valves from making high-frequency, abrasive micro-movements for a negligible error that may be caused by noise, thus improving system stability and equipment lifespan.

[0059] Optional, such as Figure 3 The control module shown implements logic calculations and control through an MCU. In this embodiment, the control module preferably uses C language as the development environment to develop the control program. The MCU control content includes:

[0060] The composite control strategy calculates and outputs the opening of the acid replenishment valve, the opening of the acid dilution valve, the heater adjustment power, and the closed status of the acid discharge valve in real time, based on the acid concentration, acid temperature, liquid level, and transmission speed values ​​fed back by the system, combined with the manually set acid concentration setpoint, temperature setpoint, and upper and lower liquid level limits. For automatic mode switching, when the system switches from automatic to manual, the integral term of the PID controller is initialized according to the current PID feedback control parameters, the previously polled PID feedback control parameters, and the actual valve position of the previous manual operation, ensuring a continuous and smooth output value before and after the switch. Conversely, when the system switches from manual to automatic, the integral term of the PID controller is initialized according to the current manual operation's actual valve position, the current automatic mode PID feedback control parameters, and the previously polled PID feedback control parameters, ensuring a continuous and smooth output value before and after the switch. The previously polled manual / automatic control status is also stored to prepare for the next manual / automatic switching action. The specific implementation includes: declaring input variable structures, output variable structures, setpoint structures, control function parameter structures, and interrupt service functions in the header file; input variable structure elements include acid concentration value, acid temperature value, liquid level height value, transmission speed value, and manual / automatic switching signal; output variable structure elements include acid replenishment valve opening degree, acid dilution valve opening degree, heater adjustment power, and acid discharge switch valve closing status; setpoint structure elements include acid concentration setpoint, temperature setpoint, and upper and lower liquid level limits; control function parameter structure elements include current PID feedback control parameters, last polled PID feedback control parameters, and last polled manual / automatic control status; all input variable structures, output variable structures, setpoint structures, and control function parameter structures pass parameters in pointer form; the main program imports the header file and defines the corresponding global variables and constants for its structures, updates the output variable structure through function calculations, and outputs it to the corresponding actuator. The advantage is that the system encapsulates all input, output, and setpoint data into a structure. When passing parameters to a function, only a structure pointer needs to be passed, which reduces the use of stack space and the time overhead of parameter passing. Furthermore, when modifying sensor-related code, it will not accidentally affect the actuator or other parts.

[0061] Specifically, the control module (MCU) packages input variables, output variables, setpoints, and parameter values ​​into a structure according to their sequential addresses. The main function parses and reads / writes this structure to achieve high real-time performance and high refresh rate response to the composite control strategy. The MCU utilizes interrupt service functions to perform composite control strategy calculations and automatic mode switching judgments, and uses the main function to switch operating states, including updating setpoints, recording data, status monitoring, and low-power management. The main program places manual / automatic mode switching judgments, safety interlock checks, and composite control strategy calculations within interrupt service functions, which are then placed within the main function. The main function uses a while loop to switch operating states, including updating setpoints, recording data, status monitoring, and low-power management. An inline feedforward control calculation function is provided for use in composite control strategy calculations. It also includes an output limiting function to prevent integral term saturation in PID feedback control; the interrupt service function calls the output limiting function to limit the final output value to the actuator. The control module (MCU) establishes input buffers for each sensor and output buffers for each actuator. Raw sensor data is stored in the sensor input buffer. The interrupt service routine (ISR) calculates the actuator output parameters and stores them in the actuator output buffer. The main function then calls the buffer to output the control parameters to the actuator, eliminating race conditions between the ISR and the main function. The ISR only writes the sampled data, while the main function only reads the current data, avoiding data corruption or inconsistency caused by simultaneous reading and writing of the same variable. Furthermore, the ISR can perform a seamless switch between manual and automatic modes. At the instant of switching from manual to automatic mode, the integral term of the PID controller is initialized with the actual valve position currently operated manually, ensuring that the controller output value is consistent before and after the switch, preventing a sudden change in the control signal and thus avoiding impact on the pickling line.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An acid pickling line monitoring system, characterized by: The control module comprises a sensor, a control module, and an actuator. The sensor monitors the acid concentration, temperature, liquid level, and driving speed of the pickling line of the pickling tank. The actuator is used to control the acid supplement, dilution, discharge, heating, and circulation of the pickling tank. The control module controls the actuator in real time according to the sensor data to maintain the acid concentration in the pickling tank near the optimal value of the pickling process. The real-time control strategy of the control module comprises an integrated compound control strategy of feedforward control and PID feedback control, which is used to adjust the output parameters of the actuator in real time. The feedforward control improves the feedforward compensation for the change of the driving speed of the pickling line. The PID feedback control sets a dead zone to reduce the disturbance of the acid concentration, temperature, and liquid level data on the output. The sensor comprises an acid concentration sensor, which is used to monitor the acid concentration value of the pickling tank and transmit the value to the control module through a 4-20 mA analog signal. The sensor comprises a temperature sensor, which is used to monitor the real-time temperature of the acid liquid in the pickling tank and transmit the temperature to the control module through a signal conversion module. The sensor comprises a liquid level sensor, which is used to monitor the liquid level and total acid amount of the pickling tank and transmit the data to the control module through a 4-20 mA analog signal. The sensor comprises an encoder, which is used to measure the driving speed of the pickling line and transmit the real-time transmission speed to the control module through a high-speed pulse signal or a field bus protocol. The actuator comprises a plurality of regulating valves, which are used to supplement and dilute the acid of the pickling tank. The regulating valves are controlled by the control module through analog output signals to adjust the opening degree of the valves. The actuator comprises a switch valve, which is used to discharge the acid liquid in the pickling tank. The switch valve is controlled by the control module through a switch signal to open or close the valve. The actuator comprises a heater, which is used to heat the temperature of the acid liquid in the pickling tank. The heater is controlled by the control module in real time through an analog output signal to adjust the heating power of the heater. The actuator comprises a circulation pump, which is used to circulate the acid liquid in the pickling tank. The circulation pump is controlled by the control module through a switch signal to start or stop the pump. The compound control strategy of the control module comprises the following steps: When the liquid level of the pickling tank is lower than a threshold value, the processor module starts a safety interlock to stop all the outputs of the actuator and close all the valves. When the monitoring system is in a manual mode, the control module directly sets all the outputs of the actuator by the staff. When the monitoring system is in an automatic mode, the control module determines whether the last program polling mode is a manual mode. If yes, the PID feedback control parameters in the last manual mode are retained, and the feedforward control is enabled. If no, the PID feedback control parameters are adjusted in real time according to the sensor data, and the feedforward control is enabled. The control module is realized by an MCU to perform logical calculation and control. The control content of the MCU comprises the following steps:

2. An acid line monitoring system according to claim 1, characterized in that: When the system is switched from the automatic mode to the manual mode, the integral term of the PID controller is initialized according to the current PID feedback control parameters, the last polling PID feedback control parameters, and the actual valve position corresponding to the current manual operation, so that the controller output is continuously smooth before and after the switching. Conversely, when the system is switched from the manual mode to the automatic mode, the integral term of the PID controller is initialized according to the current manual operation, the actual valve position, the current automatic mode PID feedback control parameters, and the last polling PID feedback control parameters, so that the controller output is continuously smooth before and after the switching. The last polling hand-automatic control state is stored to respond to the next hand-automatic switching action. The compound control strategy formula of the control module is as follows: ； ； ； wherein, is a target opening of the acid makeup regulating valve, is a feedforward control output, is a PID feedback control output, is a gain coefficient, is a real-time line speed of the pickling line drive, is a reference line speed of the pickling line drive, is a reference opening of the acid makeup regulating valve; is a proportional term, is an integral term, is a differential term, is an acid concentration target value after dead zone processing, is an effective error integral, is an acid concentration change rate for suppressing overshoot.

3. An acid line monitoring system according to claim 1, wherein: The MCU control content includes: The composite control strategy calculation is based on the system feedback of the acid concentration value, the acid liquid temperature value, the liquid level value and the transmission speed value, and combines the manually set acid concentration set value, the temperature set value and the liquid level upper and lower limits to calculate and output the acid supplement regulating valve opening, the acid dilution regulating valve opening, the heater regulating power and the acid discharge switch valve off state in real time.

4. An acid pickling line monitoring system according to claim 3, characterized in that The control module MCU packs the input variables, the output variables, the set values and the parameter values into a structure according to the order address, the main function analyzes and reads and writes the structure to realize the high real-time and high refresh rate response of the composite control strategy; The control module MCU uses the interrupt service function to execute the composite control strategy calculation and the automatic mode switching judgment, and uses the main function to switch the working states including the set value updating, the data recording, the state monitoring and the low power consumption management state.

5. An acid line monitoring system according to claim 4, wherein: The control module MCU establishes the input buffer for each sensor and the output buffer for each actuator, the sensor original data is stored in the sensor input buffer, the interrupt service function calculates the actuator output parameters and stores them in the actuator output buffer, and the buffer is called in the main function to output the actuator control parameters to eliminate the race condition between the interrupt service function and the main function.

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