Active damping type hydraulic servo control method and system for walking beam

Abstract

The invention discloses an active damping type hydraulic servo control method and system for a walking beam, which are applied to a hydraulic servo system comprising a hydraulic cylinder, a servo valve, a position sensor, a pressure sensor and a control unit, and the method is executed by the control unit. The method comprises the steps that an S-shaped motion curve generated based on the step pitch and the period is obtained to serve as a position given instruction, and the S-shaped curve defines that the acceleration of a stepping beam is linearly increased to the preset maximum value from 0 in the starting stage and linearly decreased to 0 in the braking stage; acquiring the real-time position of a cylinder rod and the real-time pressure of a hydraulic cylinder; a double-closed-loop control strategy of outer ring position feedback and inner ring pressure feedback is adopted, an opening of a servo valve is adjusted according to position deviation and a pressure sudden change signal, and active damping force opposite to the vibration direction is generated; and the real-time pressure difference values of the hydraulic cylinders are compared, when the real-time pressure difference values exceed a preset threshold value, the unbalance loading working condition is judged, and compensation is conducted by independently adjusting servo valve control parameters corresponding to the hydraulic cylinders.

Description

Technical Field

[0001] This application relates to the field of hydraulic servo control technology, and in particular to an active damping hydraulic servo control method and system for a walking beam. Background Technology

[0002] In the metallurgical industry, hydraulic servo control systems are widely used in various heavy-duty reciprocating motion equipment, such as walking beams for heating furnaces and rolling mill pressing devices. Taking hot continuous rolling mills as an example, existing technologies include methods for thickness detection and optimization using dual closed-loop feedback control (such as CN120362264A). This method achieves transmission speed control through dual closed-loop speed regulation of the drive motor's speed and current loops, adjusts rolling force through a hydraulic cylinder pressing closed-loop control system, and compensates for thickness transmission errors between stands using a thickness delay correction system. This approach improves the system's control accuracy and response speed to a certain extent, achieving good control results under continuous rolling conditions.

[0003] However, the aforementioned existing technologies mainly address thickness control under continuous steady-state operating conditions. For heavy-load reciprocating motion equipment such as walking beams that experience frequent starts, braking, and reversals, the following technical problems remain unresolved:

[0004] First, during the starting, braking, and reversing phases, the walking beam generates significant impacts and vibrations due to the rapid changes in its motion state. Existing technologies primarily focus on control accuracy during steady-state operation and do not offer effective solutions for impact suppression during transient processes such as starting and braking. Furthermore, its motion commands are often step or piecewise linear signals, inherently creating a risk of rigid impact at the source.

[0005] Second, although existing technologies employ closed-loop control of hydraulic cylinders, their feedback signals are mainly position or thickness, lacking the ability to perceive and actively intervene in real-time pressure fluctuations within the hydraulic cylinder. When the load changes abruptly, the system cannot adjust the pressure in time to balance the disturbance, leading to increased vibration and making it difficult to actively suppress shocks and vibrations.

[0006] Third, in scenarios where multiple hydraulic cylinders work together, when the load distribution is uneven (such as uneven steel billet arrangement leading to off-center loading), existing technologies cannot identify and adaptively compensate for the load deviation between each hydraulic cylinder, which can easily lead to equipment frame tilting, structural stress concentration, or even mechanical jamming or damage. Summary of the Invention

[0007] This application provides an active damping hydraulic servo control method and system for walking beams, aiming to solve the problems in the prior art such as start-up and braking shock caused by sudden changes in motion commands, lack of real-time pressure sensing and active damping capability, and inability to adaptively compensate for off-center load conditions leading to frame tilting and structural damage.

[0008] In a first aspect, an active damping hydraulic servo control method for a walking beam is provided, applied to a hydraulic servo system including a hydraulic cylinder, a servo valve, a position sensor, a pressure sensor, and a control unit. The method is executed by the control unit and includes:

[0009] Step S1: Obtain the S-shaped motion curve generated based on the step distance and cycle according to the process requirements, as a position command. The S-shaped curve defines that the acceleration of the stepping beam increases linearly from 0 to the preset maximum acceleration during the start-up phase and decreases linearly from the preset maximum acceleration to 0 during the braking phase.

[0010] Step S2: Obtain the real-time position of the cylinder rod detected by the position sensor and the real-time pressure of the hydraulic cylinder detected by the pressure sensor;

[0011] Step S3: A dual closed-loop control strategy of outer loop position feedback and inner loop pressure feedback is adopted. Based on the position deviation between the real-time position of the cylinder rod and the position command, as well as the pressure change signal of the real-time pressure of the hydraulic cylinder, the opening size of the servo valve is adjusted to generate an active damping force in the hydraulic cylinder that is opposite to the vibration direction.

[0012] Step S4: Compare the real-time pressure difference between each hydraulic cylinder. When the real-time pressure difference between any two hydraulic cylinders exceeds the preset threshold, it is determined to be an off-center load condition. Compensation is then achieved by independently adjusting the control parameters of the servo valves corresponding to each hydraulic cylinder. Specifically, the gain of the servo valve control signal is increased for the hydraulic cylinder with a larger load, and the gain of the servo valve control signal is decreased for the hydraulic cylinder with a smaller load.

[0013] Optionally, in the above scheme, step S4 further includes: when the condition is determined to be an off-center load, a cross-coupling control strategy is adopted for compensation, that is, the synchronization error between the positions of different hydraulic cylinder rods is calculated, and the position command of each hydraulic cylinder is compensated according to the synchronization error to ensure that the walking beam frame remains horizontal during the lifting and translation process.

[0014] Optionally, in the above scheme, the dual closed-loop control strategy in step S3 is as follows:

[0015] The outer ring position feedback is used to track the given position command, calculate the deviation between the real-time position of the cylinder rod and the given position command, and transmit the deviation signal to the inner ring pressure feedback;

[0016] The inner loop pressure feedback is used to receive the deviation signal transmitted from the outer loop and the real-time pressure signal detected by the pressure sensor. When a sudden pressure change is detected, the opening of the servo valve is immediately adjusted to smooth the pressure fluctuation.

[0017] Optionally, in the above scheme, the pressure change signal in step S3 is determined by comparing the real-time pressure of the hydraulic cylinder with the preset normal pressure value. When the real-time pressure exceeds the preset percentage of the normal pressure value, it is determined to be a pressure change.

[0018] Optionally, in the above scheme, the fuzzy PID algorithm is used to adjust the opening size of the servo valve in step S3. The fuzzy PID algorithm adjusts the PID parameters in real time through fuzzy rules to adapt to the dynamic characteristics of the stepper beam at different motion stages.

[0019] In the above scheme, optionally, the preset threshold in step S4 is set according to the rated load and structural strength of the walking beam. The off-center load condition is identified by comparing the real-time pressure difference of each hydraulic cylinder. When the real-time pressure difference between any two hydraulic cylinders exceeds the preset threshold, it is determined that there is an off-center load.

[0020] Secondly, an active damping hydraulic servo control system for a walking beam is provided, comprising:

[0021] A hydraulic actuator includes a hydraulic cylinder and a high-response servo valve, the servo valve being connected to the hydraulic cylinder to control the movement of the hydraulic cylinder;

[0022] The sensing and detection unit includes a position sensor and a pressure sensor. The position sensor is used to detect the real-time position of the hydraulic cylinder rod, and the pressure sensor is used to detect the real-time pressure inside the hydraulic cylinder.

[0023] An ideal motion trajectory planner based on the S-curve is used to automatically generate an S-shaped motion curve according to the step size and cycle required by the process, and use the S-shaped curve as the position command of the servo system; wherein, the S-shaped motion curve defines the acceleration of the stepper beam as increasing from 0 to a preset maximum acceleration at a constant jerk during the start-up phase, and decreasing from the preset maximum acceleration to 0 at a constant jerk during the braking phase.

[0024] The control unit is electrically connected to the sensing and detection unit, the servo valve, and the ideal motion trajectory planner, and is used to execute the steps of the above method.

[0025] In the above scheme, optionally, the control unit adopts a pressure-position composite feedback servo control strategy, specifically a dual closed-loop control structure with outer loop position feedback and inner loop pressure feedback;

[0026] The outer ring position feedback is used to track the position command generated based on the S-curve, calculate the deviation between the real-time position of the cylinder rod and the position command, and transmit the deviation signal to the inner ring pressure feedback;

[0027] The inner loop pressure feedback is used to receive the deviation signal transmitted from the outer loop and the real-time pressure signal detected by the pressure sensor. When a sudden pressure change is detected, the opening of the servo valve is immediately adjusted to smooth the pressure fluctuation and generate an active damping force opposite to the vibration direction.

[0028] Optionally, in the above scheme, the control algorithm in the control unit is a fuzzy PID algorithm. The fuzzy PID algorithm adjusts the PID parameters in real time through fuzzy rules to adapt to the dynamic characteristics of the walking beam at different motion stages.

[0029] Optionally, in the above scheme, the control unit further includes: when an off-center load is detected, a cross-coupling control strategy is adopted to calculate the synchronization error between the positions of different hydraulic cylinder rods, and the position command given by each hydraulic cylinder is compensated according to the synchronization error to ensure that the walking beam frame remains horizontal during the lifting and translation process.

[0030] Compared with the prior art, this application has at least the following beneficial effects:

[0031] Based on further analysis and research of existing technical problems, this application recognizes that existing technologies suffer from issues such as start-up and braking shocks caused by sudden changes in motion commands, lack of real-time pressure sensing and active damping capabilities, and inability to adaptively compensate for off-center load conditions leading to frame tilting and structural damage. This application adds a highly responsive servo valve and pressure sensor to the traditional hydraulic system. It generates smooth motion commands through an ideal motion trajectory planner based on an S-curve, and combines a pressure-position composite feedback dual-closed-loop servo control strategy to adjust the hydraulic cylinder pressure in real time to actively generate reverse damping force. Simultaneously, for off-center load conditions caused by uneven billet distribution, an adaptive control mechanism is designed. This mechanism compensates for synchronization errors by independently adjusting the parameters of each cylinder or through cross-coupling control, ensuring smooth operation of the walking beam and effectively avoiding mechanical damage, furnace lining damage, and billet deviation or scratches. This achieves "compliant" billet transport and is suitable for heavy-duty reciprocating motion equipment such as walking beams for heating furnaces in the metallurgical industry.

[0032] This application also has at least the following beneficial effects:

[0033] (1) Significant impact and vibration suppression effect: Step impact is eliminated by S-curve trajectory planning, and damping force is actively generated by pressure-position dual closed loop control, which can reduce the impact acceleration and vibration amplitude during the start-up, braking and reversal of the walking beam, effectively protecting the mechanical structure and furnace lining.

[0034] (2) Improved billet transportation quality: Stable movement avoids billet deviation and surface scratches, reducing the surface scratch rate of billets;

[0035] (3) The system is robust: the off-center load adaptive control mechanism can adapt to the working conditions of uneven billet arrangement, ensuring that the walking beam can still operate stably when the load changes, and reducing the equipment failure rate;

[0036] (4) Good versatility: The S-curve parameters and control algorithm parameters can be adjusted according to the process requirements (step distance, cycle, load) of different specifications of walking beams, and it is suitable for walking beam equipment of various metallurgical heating furnaces. Attached Figure Description

[0037] Figure 1 A diagram of an active damping hydraulic servo control system for a walking beam provided in one embodiment of this application.

[0038] Figure 2 This diagram illustrates a dual-closed-loop servo control strategy employing pressure-position composite feedback in one embodiment of this application.

[0039] Figure 3 A flow diagram of an active damping hydraulic servo control method for a walking beam, provided in one embodiment of this application.

[0040] Among them, 1 is the hydraulic power unit; 2 is the fixed beam; 3 is the position sensor; 4 is the pressure sensor; 5 is the servo valve; 6 is the hydraulic cylinder; 7 is the control unit; 8 is the ideal motion trajectory planner based on the S-curve; 9 is the steel billet; and 10 is the movable beam. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0042] In the description of this application: unless otherwise stated, "a plurality of" means two or more. The terms "first," "second," "third," etc., in this application are intended to distinguish the objects referred to and do not have any special meaning in terms of technical connotation (e.g., they should not be construed as an emphasis on importance or order). Expressions such as "including," "comprising," and "having" also mean "not limited to" (certain units, components, materials, steps, etc.).

[0043] In the metallurgical industry's heating furnace production process, the walking beam is the core equipment for conveying steel billets. Through periodic lifting and translating movements, it transports the billets from the furnace opening to a designated position inside the furnace or removes them from the furnace. However, during the start-up, braking, and reversing phases, the walking beam experiences significant impacts and vibrations due to the rapid changes in its motion. These impacts and vibrations not only cause fatigue damage to the mechanical structure of the walking beam (such as the crossbeams, columns, and transmission mechanism), shortening the equipment's service life, but may also lead to cracking or detachment of the furnace lining, affecting the normal operation of the heating furnace. More seriously, the impacts and vibrations can cause the steel billets to deviate from their designated position inside the furnace, or even collide with the furnace wall or other steel billets, resulting in surface scratches and reducing the quality of the steel billet product.

[0044] Currently, walking beam systems are typically driven by traditional hydraulic control systems. These systems are mostly based on simple switch control or single-loop position control, lacking the ability to actively suppress shocks and vibrations. Specifically, the motion commands of traditional systems are mostly step signals, which can easily generate rigid impacts during startup and braking. Furthermore, the system relies solely on position feedback for control and cannot detect pressure changes within the hydraulic cylinders in real time. When the load changes abruptly (such as a shift in the billet's center of gravity), it cannot adjust the pressure in time to balance the load, leading to increased vibration. In addition, when the billets are unevenly distributed on the walking beam, it causes load deviations in each hydraulic cylinder (i.e., off-center loading). Traditional systems cannot adaptively compensate for off-center loading, which can easily cause the walking beam frame to tilt, further exacerbating structural stress and equipment damage.

[0045] Therefore, there is an urgent need for a hydraulic servo control system for stepper beams that can actively suppress shock and vibration and adapt to off-center load conditions, in order to solve the above-mentioned problems in the existing technology and achieve smooth and "compliant" transportation of steel billets.

[0046] This invention aims to solve the following problems existing in the hydraulic control system of a walking beam:

[0047] (1) The motion command is a step signal, which is prone to rigid impact during starting, braking and reversing;

[0048] (2) Relying solely on position feedback control, it cannot sense pressure changes in real time, lacks active damping capability, and has poor vibration suppression effect;

[0049] (3) It is impossible to identify and adapt to the off-center load conditions, which can easily lead to the tilting, jamming and structural damage of the walking beam.

[0050] In one embodiment, an active damping hydraulic servo control method for a walking beam is provided, applied to a hydraulic servo system including a hydraulic cylinder, a servo valve, a position sensor, a pressure sensor, and a control unit. The method is executed by the control unit and includes:

[0051] Step S1: Obtain the S-shaped motion curve generated based on the step distance and cycle according to the process requirements, as a position command. The S-shaped curve defines that the acceleration of the stepping beam increases linearly from 0 to the preset maximum acceleration during the start-up phase and decreases linearly from the preset maximum acceleration to 0 during the braking phase.

[0052] Step S2: Obtain the real-time position of the cylinder rod detected by the position sensor and the real-time pressure of the hydraulic cylinder detected by the pressure sensor;

[0053] Step S3: A dual closed-loop control strategy of outer loop position feedback and inner loop pressure feedback is adopted. Based on the position deviation between the real-time position of the cylinder rod and the position command, as well as the pressure change signal of the real-time pressure of the hydraulic cylinder, the opening size of the servo valve is adjusted to generate an active damping force in the hydraulic cylinder that is opposite to the vibration direction.

[0054] Step S4: Compare the real-time pressure difference between each hydraulic cylinder. When the real-time pressure difference between any two hydraulic cylinders exceeds the preset threshold, it is determined to be an off-center load condition. Compensation is then achieved by independently adjusting the control parameters of the servo valves corresponding to each hydraulic cylinder. Specifically, the gain of the servo valve control signal is increased for the hydraulic cylinder with a larger load, and the gain of the servo valve control signal is decreased for the hydraulic cylinder with a smaller load.

[0055] In one embodiment, an active damping hydraulic servo control method for a walking beam is provided, applied to a hydraulic servo system including a hydraulic cylinder, a servo valve, a position sensor, a pressure sensor, and a control unit (see [link to documentation]). Figures 1-3 The method is executed by the control unit and includes:

[0056] Step S1: Obtain the S-shaped motion curve generated based on the step distance and cycle according to the process requirements, as the position command. The S-shaped curve defines the acceleration of the walking beam as linearly increasing from 0 to a preset maximum acceleration during the start-up phase, and linearly decreasing from the preset maximum acceleration to 0 during the braking phase. Taking the lifting phase as an example, an S-shaped lifting trajectory is generated according to the lifting cycle and stroke: During the start-up phase (0-1s), the acceleration linearly increases from 0 to 0.1m / s², and the speed increases from 0 to 0.1m / s; during the constant speed phase (1-6s), the acceleration remains 0, and the speed stabilizes at 0.1m / s; during the braking phase (6-8s), the acceleration linearly decreases from 0.1m / s² to 0, and the speed drops to 0.

[0057] Step S2: Obtain the real-time position of the cylinder rod detected by the position sensor and the real-time pressure of the hydraulic cylinder detected by the pressure sensor.

[0058] Step S3 employs a dual closed-loop control strategy with outer loop position feedback and inner loop pressure feedback (see...). Figure 2Based on the position deviation between the real-time position of the cylinder rod and the given position command, as well as the pressure surge signal of the real-time pressure of the hydraulic cylinder, the opening size of the servo valve is adjusted to generate an active damping force in the hydraulic cylinder opposite to the direction of vibration. In one example, the pressure surge signal is determined by comparing the real-time pressure of the hydraulic cylinder with a preset normal pressure value. When the real-time pressure exceeds a preset percentage (e.g., 13%) of the normal pressure value, it is determined to be a pressure surge, and the control unit immediately adjusts the opening of the servo valve to smooth the pressure fluctuation.

[0059] Step S4: Compare the real-time pressure difference between each hydraulic cylinder. When the real-time pressure difference between any two hydraulic cylinders exceeds the preset threshold, it is determined to be an off-center load condition. Compensation is then achieved by independently adjusting the control parameters of the servo valves corresponding to each hydraulic cylinder. Specifically, the gain of the servo valve control signal is increased for the hydraulic cylinder with a larger load, and the gain of the servo valve control signal is decreased for the hydraulic cylinder with a smaller load.

[0060] In one embodiment, step S4 further includes: when the condition is determined to be an off-center load, a cross-coupling control strategy is adopted for compensation, that is, the synchronization error between the positions of different hydraulic cylinder rods is calculated, and the position command of each hydraulic cylinder is compensated according to the synchronization error to ensure that the walking beam frame remains horizontal during the lifting and translation process.

[0061] In one embodiment, step S4 further includes: when an off-center load condition is determined, a cross-coupling control strategy is used for compensation, that is, the synchronization error between the cylinder rod positions of different hydraulic cylinders is calculated, and the position command of each hydraulic cylinder is compensated according to the synchronization error to ensure that the walking beam frame remains horizontal during lifting and translation. For example, when the cylinder rod position of the left hydraulic cylinder lags behind the position command by 5mm, the control unit adds a 5mm compensation amount to the position command of the right hydraulic cylinder to accelerate the movement speed of the right hydraulic cylinder and restore the walking beam frame to horizontality.

[0062] In one embodiment, in step S3, the dual closed-loop control strategy specifically refers to:

[0063] The outer ring position feedback is used to track the given position command, calculate the deviation between the real-time position of the cylinder rod and the given position command, and transmit the deviation signal to the inner ring pressure feedback;

[0064] The inner loop pressure feedback is used to receive the deviation signal transmitted from the outer loop and the real-time pressure signal detected by the pressure sensor. When a sudden pressure change is detected, the opening of the servo valve is immediately adjusted to smooth the pressure fluctuation.

[0065] The control unit employs a dual closed-loop control strategy with outer loop position feedback and inner loop pressure feedback (see...). Figure 2Based on the position deviation between the real-time position of the cylinder rod and the given position command, as well as the pressure change signal of the real-time pressure of the hydraulic cylinder, the opening size of the servo valve is adjusted to generate an active damping force in the hydraulic cylinder that is opposite to the direction of vibration.

[0066] Specifically, the outer ring position feedback is used to track the given position command, calculate the deviation between the real-time position of the cylinder rod and the given position command, and transmit the deviation signal to the inner ring pressure feedback; the inner ring pressure feedback is used to receive the deviation signal transmitted from the outer ring and the real-time pressure signal detected by the pressure sensor, and when a pressure change is detected, it immediately adjusts the opening of the servo valve to smooth the pressure fluctuation.

[0067] In one example, the pressure surge signal is determined by comparing the real-time pressure of the hydraulic cylinder with a preset normal pressure value. When the real-time pressure exceeds a preset percentage (e.g., 13%) of the normal pressure value, it is determined to be a pressure surge. The inner loop controller immediately adjusts the servo valve opening to bring the pressure back to the normal range.

[0068] In one embodiment, the pressure surge signal in step S3 is determined by comparing the real-time pressure of the hydraulic cylinder with a preset normal pressure value. When the real-time pressure exceeds a preset percentage of the normal pressure value, it is determined to be a pressure surge. In a specific example, the preset percentage is 13%, meaning that when the real-time pressure of the hydraulic cylinder exceeds 13% of the normal pressure value, it is determined to be a pressure surge. The control unit immediately adjusts the servo valve opening to bring the pressure back to the normal range, thereby generating an active damping force to suppress vibration.

[0069] In one embodiment, the fuzzy PID algorithm is used to adjust the opening size of the servo valve in step S3. The fuzzy PID algorithm adjusts the PID parameters in real time through fuzzy rules to adapt to the dynamic characteristics of the stepper beam at different motion stages.

[0070] In one embodiment, the adjustment of the servo valve opening size in step S3 employs a fuzzy PID algorithm. Specifically, the control unit uses position deviation and pressure deviation as input variables for the fuzzy controller, and adjusts the PID parameters (proportional coefficient Kp, integral coefficient Ki, and derivative coefficient Kd) in real time according to preset fuzzy rules to adapt to the dynamic characteristics of the walking beam at different motion stages.

[0071] For example, during the start-up phase, the stepping beam is in an accelerating state with a large system inertia. The fuzzy PID algorithm increases the proportional coefficient to improve the response speed while decreasing the derivative coefficient to avoid overshoot. During the constant speed phase, the stepping beam is in a stable motion state. The fuzzy PID algorithm decreases the proportional coefficient to reduce steady-state error while increasing the integral coefficient to eliminate residual deviation. During the braking phase, the stepping beam is in a decelerating state. The fuzzy PID algorithm increases the derivative coefficient to enhance the system's damping characteristics and suppress shocks and vibrations during braking.

[0072] In one embodiment, the preset threshold in step S4 is set according to the rated load and structural strength of the walking beam. The off-center load condition is identified by comparing the real-time pressure difference between each hydraulic cylinder. When the real-time pressure difference between any two hydraulic cylinders exceeds the preset threshold, it is determined that there is an off-center load.

[0073] In one example, the preset threshold is set to 15% of the pressure corresponding to the rated load of the walking beam. For example, when the real-time pressure difference between the left and right hydraulic cylinders exceeds this threshold, the control unit determines that it is an off-center load condition and immediately performs subsequent off-center load compensation operations (such as independently adjusting the servo valve control parameters or adopting a cross-coupling control strategy).

[0074] In one embodiment, combined Figure 1 An active damping hydraulic servo control system for a walking beam is described, and the overall process of the method in this application is outlined. The working process of this system is divided into a lifting stage and a translation stage, as detailed below:

[0075] (1) Lifting and lowering stage.

[0076] Trajectory planning: The ideal motion trajectory planner 8 generates an S-shaped lifting trajectory based on the lifting cycle and stroke. For example, from 0 to 1s (starting phase), the acceleration increases linearly from 0 to 0.1m / s², and the speed increases from 0 to 0.1m / s; from 1 to 6s (uniform speed phase), the acceleration remains at 0, and the speed stabilizes at 0.1m / s; from 6 to 8s (braking phase), the acceleration decreases linearly from 0.1m / s² to 0, and the speed drops to 0, completing the lifting action.

[0077] Dual closed-loop control: Control unit 7 receives the position command of the S-shaped trajectory. The outer loop position feedback calculates the deviation between the real-time position of the cylinder rod (detected by displacement sensor 3) and the command position, and transmits the deviation signal to the inner loop. The inner loop pressure feedback receives the deviation signal and the hydraulic cylinder pressure signal (rodless chamber pressure and rod chamber pressure) detected by pressure sensor 4, and adjusts the opening of servo valve 5 through fuzzy PID algorithm: When the center of gravity of the billet shifts, causing the pressure of a certain cylinder to suddenly increase to more than 13% above the normal pressure, the inner loop controller immediately reduces the opening of servo valve 5 of that cylinder, reduces the oil intake of the rodless chamber, and causes the pressure to drop back to the normal pressure, generating a reverse damping force to suppress vibration.

[0078] Off-center load adaptive adjustment: If the billet 9 is biased to one side of the walking beam 10, causing the pressure difference between the two cylinders 6 on the left and the two cylinders 6 on the right to reach the threshold, the system determines that it is an off-center load: On the one hand, the control signal gain of the servo valve of the two cylinders on the right is increased independently, so that the output force of the cylinder on the right increases; on the other hand, the position synchronization error between the cylinder on the left and the cylinder on the right is calculated by cross-coupling control (assuming that the position of the cylinder on the left is 5mm behind the command), and the 5mm compensation is added to the position command of the cylinder on the right, so as to speed up the movement speed of the cylinder on the right and restore the walking beam frame to horizontal.

[0079] (2) Translation stage

[0080] The working principle of the translation phase is the same as that of the lifting phase, only the trajectory parameters are different: based on the translation period and step distance, the starting phase, constant speed phase, braking phase, maximum acceleration and maximum speed of the S-shaped translation trajectory are calculated. The dual closed-loop control and off-center load adaptive adjustment process are the same as those of the lifting phase, ensuring that the translation process is smooth and shock-free.

[0081] In summary, the active damping hydraulic servo control system for walking beams in this embodiment can effectively suppress impacts and vibrations, adapt to off-center load conditions, achieve "compliant" transport of steel billets, and meet the production requirements of walking beams for metallurgical heating furnaces.

[0082] In one embodiment, an active damping hydraulic servo control system for a walking beam is provided, comprising:

[0083] A hydraulic actuator includes a hydraulic cylinder and a high-response servo valve, the servo valve being connected to the hydraulic cylinder to control the movement of the hydraulic cylinder;

[0084] The sensing and detection unit includes a position sensor and a pressure sensor. The position sensor is used to detect the real-time position of the hydraulic cylinder rod, and the pressure sensor is used to detect the real-time pressure inside the hydraulic cylinder.

[0085] An ideal motion trajectory planner based on the S-curve is used to automatically generate an S-shaped motion curve according to the step size and cycle required by the process, and use the S-shaped curve as the position command of the servo system; wherein, the S-shaped motion curve defines the acceleration of the stepper beam as increasing from 0 to a preset maximum acceleration at a constant jerk during the start-up phase, and decreasing from the preset maximum acceleration to 0 at a constant jerk during the braking phase.

[0086] The control unit is electrically connected to the sensing and detection unit, the servo valve, and the ideal motion trajectory planner, and is used to execute the steps of the above method.

[0087] In one embodiment, the control unit adopts a pressure-position composite feedback servo control strategy, specifically a dual closed-loop control structure with outer loop position feedback and inner loop pressure feedback;

[0088] The outer ring position feedback is used to track the position command generated based on the S-curve, calculate the deviation between the real-time position of the cylinder rod and the position command, and transmit the deviation signal to the inner ring pressure feedback;

[0089] The inner loop pressure feedback is used to receive the deviation signal transmitted from the outer loop and the real-time pressure signal detected by the pressure sensor. When a sudden pressure change is detected, the opening of the servo valve is immediately adjusted to smooth the pressure fluctuation and generate an active damping force opposite to the vibration direction.

[0090] In one embodiment, the control algorithm in the control unit is a fuzzy PID algorithm, which adjusts the PID parameters in real time using fuzzy rules to adapt to the dynamic characteristics of the walking beam at different motion stages.

[0091] In one embodiment, the control unit further includes: when an off-center load is detected, employing a cross-coupling control strategy to calculate the synchronization error between the positions of different hydraulic cylinder rods, and compensating for the positional command of each hydraulic cylinder based on the synchronization error, so as to ensure that the walking beam frame remains horizontal during the lifting and translation process.

[0092] To achieve the above objectives, the present invention provides an active damping hydraulic servo control system for a walking beam, the specific technical solution of which is as follows:

[0093] The system includes a hydraulic actuator, a sensing and detection unit, a control unit, an ideal motion trajectory planner based on the S-curve, and an off-center load adaptive control mechanism.

[0094] (1) Ideal motion trajectory planner based on S-curve.

[0095] The planner automatically generates an S-shaped motion curve based on the required step distance (i.e., the distance of a single translation or lifting movement of the walking beam) and cycle (i.e., the time to complete one lifting and translation movement). The design principle of the S-shaped curve is as follows: during the motion initiation phase, the acceleration increases linearly from 0 to the preset maximum acceleration (avoiding sudden acceleration changes); during the constant speed phase, the acceleration remains at 0, and the speed is stable; during the braking phase, the acceleration decreases linearly from the preset maximum acceleration to 0, achieving a smooth speed transition. The position command generated by this planner eliminates the rigid impact caused by step commands at the source, laying the foundation for the smooth movement of the walking beam.

[0096] (2) Dual closed-loop servo control strategy with pressure-position composite feedback.

[0097] The control unit adopts a dual closed-loop structure with outer loop position feedback and inner loop pressure feedback.

[0098] Outer ring position feedback: Receives position command based on S-curve and real-time position signal of cylinder rod detected by position sensor, calculates position deviation, and transmits deviation signal to inner ring to ensure that the motion trajectory of stepper beam accurately tracks command trajectory;

[0099] Inner loop pressure feedback: Receives the position deviation signal transmitted from the outer loop and the real-time pressure signal of the hydraulic cylinder detected by the pressure sensor. When a pressure change is detected (indicating that an impact is about to occur or has already occurred), the inner loop controller immediately adjusts the opening size of the servo valve through a fuzzy PID algorithm to change the pressure in the hydraulic cylinder, thereby generating a damping force opposite to the vibration direction and actively suppressing the vibration.

[0100] The fuzzy PID algorithm dynamically adjusts parameters in real time, solving the problem of poor adaptability of the traditional PID algorithm in different motion stages (starting, constant speed, braking), and improving control accuracy and response speed.

[0101] (3) Off-center load adaptive control mechanism.

[0102] This mechanism is integrated into the control unit. It uses pressure sensors to detect the real-time pressure of each hydraulic cylinder and calculates the pressure difference between them. When the pressure difference between any two hydraulic cylinders exceeds a preset threshold (set based on the rated load and structural strength of the walking beam), an off-center load condition is identified. For off-center loads, the system employs two adaptive adjustment methods:

[0103] Independent parameter adjustment: For hydraulic cylinders with large loads, increase the control signal gain of the corresponding servo valve to increase the output force of the cylinder; for hydraulic cylinders with small loads, decrease the control signal gain to reduce the output force and achieve load balance among cylinders.

[0104] Cross-coupling control: Calculate the synchronization error of the position of each hydraulic cylinder rod, compensate the synchronization error into the position command of each cylinder, adjust the movement speed of each cylinder, and ensure that the walking beam frame remains horizontal during lifting and translation, avoiding jamming and structural stress concentration caused by frame tilting.

[0105] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A method for active damping hydraulic servo control of a walking beam, characterized in that, Applied to a hydraulic servo system including a hydraulic cylinder, a servo valve, a position sensor, a pressure sensor, and a control unit, the method is executed by the control unit and includes: Step S1: Obtain the S-shaped motion curve generated based on the step distance and cycle according to the process requirements, as a position command. The S-shaped curve defines that the acceleration of the stepping beam increases linearly from 0 to the preset maximum acceleration during the start-up phase and decreases linearly from the preset maximum acceleration to 0 during the braking phase. Step S2: Obtain the real-time position of the cylinder rod detected by the position sensor and the real-time pressure of the hydraulic cylinder detected by the pressure sensor; Step S3: A dual closed-loop control strategy of outer loop position feedback and inner loop pressure feedback is adopted. Based on the position deviation between the real-time position of the cylinder rod and the position command, as well as the pressure change signal of the real-time pressure of the hydraulic cylinder, the opening size of the servo valve is adjusted to generate an active damping force in the hydraulic cylinder that is opposite to the vibration direction. Step S4: Compare the real-time pressure difference between each hydraulic cylinder. When the real-time pressure difference between any two hydraulic cylinders exceeds the preset threshold, it is determined to be an off-center load condition. Compensation is then achieved by independently adjusting the control parameters of the servo valves corresponding to each hydraulic cylinder. Specifically, the gain of the servo valve control signal is increased for the hydraulic cylinder with a larger load, and the gain of the servo valve control signal is decreased for the hydraulic cylinder with a smaller load.

2. The method according to claim 1, characterized in that, In step S4, the method further includes: when the condition is determined to be an off-center load, a cross-coupling control strategy is adopted for compensation, that is, the synchronization error between the positions of different hydraulic cylinder rods is calculated, and the position command of each hydraulic cylinder is compensated according to the synchronization error to ensure that the walking beam frame remains horizontal during the lifting and translation process.

3. The method according to claim 1, characterized in that, In step S3, the dual closed-loop control strategy is specifically as follows: The outer ring position feedback is used to track the given position command, calculate the deviation between the real-time position of the cylinder rod and the given position command, and transmit the deviation signal to the inner ring pressure feedback; The inner loop pressure feedback is used to receive the deviation signal transmitted from the outer loop and the real-time pressure signal detected by the pressure sensor. When a sudden pressure change is detected, the opening of the servo valve is immediately adjusted to smooth the pressure fluctuation.

4. The method according to claim 1 or 3, characterized in that, The pressure mutation signal mentioned in step S3 is determined by comparing the real-time pressure of the hydraulic cylinder with the preset normal pressure value. When the real-time pressure exceeds the preset percentage of the normal pressure value, it is determined to be a pressure mutation.

5. The method according to claim 1 or 3, characterized in that, In step S3, the opening size of the servo valve is adjusted using a fuzzy PID algorithm. The fuzzy PID algorithm adjusts the PID parameters in real time using fuzzy rules to adapt to the dynamic characteristics of the stepper beam at different motion stages.

6. The method according to claim 1, characterized in that, The preset threshold mentioned in step S4 is set according to the rated load and structural strength of the walking beam. The off-center load condition is identified by comparing the real-time pressure difference of each hydraulic cylinder. When the real-time pressure difference between any two hydraulic cylinders exceeds the preset threshold, it is determined that there is an off-center load.

7. An active damping hydraulic servo control system for a walking beam, characterized in that, include: A hydraulic actuator includes a hydraulic cylinder and a high-response servo valve, the servo valve being connected to the hydraulic cylinder to control the movement of the hydraulic cylinder; The sensing and detection unit includes a position sensor and a pressure sensor. The position sensor is used to detect the real-time position of the hydraulic cylinder rod, and the pressure sensor is used to detect the real-time pressure inside the hydraulic cylinder. An ideal motion trajectory planner based on the S-curve is used to automatically generate an S-shaped motion curve according to the step size and cycle required by the process, and use the S-shaped curve as the position command of the servo system; wherein, the S-shaped motion curve defines the acceleration of the stepper beam as increasing from 0 to a preset maximum acceleration at a constant jerk during the start-up phase, and decreasing from the preset maximum acceleration to 0 at a constant jerk during the braking phase. The control unit is electrically connected to the sensing and detection unit, the servo valve, and the ideal motion trajectory planner, respectively, and the control unit is used to execute the method described in claim 1.

8. The system according to claim 7, characterized in that, The control unit adopts a pressure-position composite feedback servo control strategy, specifically a dual closed-loop control structure with outer loop position feedback and inner loop pressure feedback; The outer ring position feedback is used to track the position command generated based on the S-curve, calculate the deviation between the real-time position of the cylinder rod and the position command, and transmit the deviation signal to the inner ring pressure feedback; The inner loop pressure feedback is used to receive the deviation signal transmitted from the outer loop and the real-time pressure signal detected by the pressure sensor. When a sudden pressure change is detected, the opening of the servo valve is immediately adjusted to smooth the pressure fluctuation and generate an active damping force opposite to the vibration direction.

9. The system according to claim 7, characterized in that, The control algorithm in the control unit is a fuzzy PID algorithm. The fuzzy PID algorithm adjusts the PID parameters in real time through fuzzy rules to adapt to the dynamic characteristics of the walking beam at different motion stages.

10. The system according to claim 7, characterized in that, The control unit also includes: when off-center load is detected, a cross-coupling control strategy is adopted to calculate the synchronization error between the positions of different hydraulic cylinder rods, and the position command of each hydraulic cylinder is compensated according to the synchronization error to ensure that the walking beam frame remains horizontal during the lifting and translation process.

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