Hydraulic machine sliding block descending speed deviation control method

Abstract

This invention discloses a method for controlling the downward speed deviation of a hydraulic press slide, belonging to the field of hydraulic press control technology. The method first collects real-time signals of slide position, main cylinder pressure, and oil temperature, and calculates the speed deviation. When the speed deviation continuously exceeds the limit, the system automatically switches from basic PID control to adaptive fuzzy PID control mode. In this mode, the system comprehensively considers the speed deviation, its rate of change, and pressure signals, determines the dominant disturbance type online according to preset rules, and generates targeted compensation commands accordingly. Through a multi-disturbance coordination strategy, the commands are output in an orderly manner to actuators such as proportional valves, cooling valves, and hydraulic pumps. The system monitors the speed deviation in a closed loop, achieving automatic mode recovery or abnormal protection. This invention achieves accurate identification and dynamic compensation of multiple disturbances, significantly improving the control accuracy, anti-interference capability, and system intelligence level of the slide speed.

Description

Technical Field

[0001] This invention relates to the field of hydraulic press control technology, and in particular to a method for controlling the deviation of the downward speed of a hydraulic press slide. Background Technology

[0002] Hydraulic presses, as processing equipment that transmits energy through liquid pressure, are widely used in industrial fields such as stamping, forging, press fitting, and bending. The slide block, as the core actuator of the hydraulic press, directly determines the workpiece processing quality through the stability and control precision of its downward speed.

[0003] Currently, the mainstream slider speed control methods in the industry mainly include open-loop control, traditional closed-loop control, and simple PID control, but all of them have significant limitations. Open-loop control adjusts the speed by preset parameters such as hydraulic pump displacement and control valve opening, without real-time feedback.

[0004] Traditional closed-loop control, while using displacement sensors to provide speed feedback, suffers from the following shortcomings: interference factors are not quantitatively compensated for; it relies solely on adjusting the speed deviation of a single slider, failing to systematically analyze the coupled effects of multiple factors such as load, oil temperature, and leakage on speed. For example, when the load increases, the rise in main cylinder pressure can cause a sudden drop in speed, but traditional control cannot predict and compensate for this in advance.

[0005] The controller has poor adaptability and mostly uses PID control with fixed parameters. When faced with complex working conditions (such as sudden load changes or oil temperature rising from 30℃ to 60℃), the parameters cannot be dynamically adjusted, which easily leads to "overshoot" or "response lag". The slider speed deviation often exceeds ±0.3mm / s.

[0006] To address the shortcomings of the prior art, this invention provides a method for controlling the downward speed deviation of a hydraulic press slide, thereby ultimately improving product processing quality. Summary of the Invention

[0007] The purpose of this invention is to solve the problems existing in the prior art and to propose a method for controlling the downward speed deviation of a hydraulic press slider.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: a method for controlling the downward speed deviation of a hydraulic press slide, comprising a data acquisition module, a processing module, an actuator, an alarm device, and a data recording module electrically connected to a controller, wherein the controller integrates basic PID and adaptive fuzzy PID, and includes the following steps:

[0009] S1. Real-time acquisition of slider position, main cylinder inlet / outlet pressure and hydraulic oil temperature signals;

[0010] S2. Calculate the actual speed of the slider based on the slider position signal, and compare it with the preset target speed to obtain the speed deviation and the rate of change of speed deviation;

[0011] S3. If the speed deviation continues to exceed the preset tolerance threshold, it is determined that the current control accuracy is insufficient, and the system automatically switches from the basic PID control mode to the adaptive fuzzy PID control mode.

[0012] S4. In the adaptive fuzzy PID control mode, when the absolute value of the speed deviation is greater than the tolerance threshold, the current dominant disturbance type is determined based on the speed deviation, the rate of change of speed deviation and the pressure signal, according to the preset mapping rules; the dominant disturbance type includes load disturbance, oil temperature disturbance and leakage disturbance.

[0013] S5. Generate corresponding compensation instructions based on the determined dominant interference type;

[0014] S6. Based on the currently determined dominant interference type and the preset multi-interference coordination strategy, output the compensation command generated in S5 to the corresponding execution mechanism for execution;

[0015] S7. Closed-loop monitoring and status decision: Continuously monitor the speed deviation. If it returns to the tolerance threshold and remains stable, switch back to the basic PID mode. If it continues to exceed the limit, trigger the abnormal protection process. Otherwise, repeat steps S4 to S6.

[0016] Furthermore, in S4, the mapping rule is as follows:

[0017] When the first set of composite conditions is met, the load interference is determined to be the dominant factor.

[0018] When the second set of composite conditions is met, oil temperature interference is determined to be the dominant factor.

[0019] When the third set of composite conditions is met, leakage interference is determined to be the dominant factor.

[0020] Each set of composite conditions is determined based on a comprehensive assessment of speed deviation, speed deviation change rate, duration, and key correlation parameters of the corresponding type.

[0021] Furthermore, the first set of composite conditions includes: the absolute value of the speed deviation is greater than the speed deviation threshold used for load disturbance determination, the absolute value of the speed deviation change rate is greater than the first change rate threshold, the duration of the deviation and change rate exceeding the limit is less than the first duration threshold, and the pressure difference between the inlet and outlet is greater than the first pressure difference threshold or its change rate is greater than the first pressure change rate threshold.

[0022] The second set of composite conditions includes: the absolute value of the speed deviation is greater than the speed deviation threshold used for oil temperature interference determination, the absolute value of the speed deviation change rate is less than or equal to the second change rate threshold, the duration of the oil temperature interference is greater than or equal to the second duration threshold, and the oil temperature deviation is greater than the oil temperature deviation threshold or its change rate is greater than the oil temperature change rate threshold.

[0023] The third set of composite conditions includes: the absolute value of the velocity deviation is greater than the velocity deviation threshold used for leakage interference determination; the absolute value of the velocity deviation change rate is greater than the third change rate threshold and less than or equal to the fourth change rate threshold; the duration of the leakage interference is greater than or equal to the third duration threshold; and the leakage flow rate estimated based on the state-space model is greater than the rated leakage rate benchmark value.

[0024] Furthermore, the state variables of the state space model include: actual slider speed, main cylinder inlet / outlet pressure, hydraulic oil temperature, and estimated leakage.

[0025] Furthermore, in step S5, based on the dominant interference type, a corresponding fuzzy rule subset is activated. This fuzzy rule subset includes a first fuzzy rule subset, a second fuzzy rule subset, and a third fuzzy rule subset. The parameters of the adaptive fuzzy PID controller are adjusted, and physical execution instructions are generated.

[0026] To address load interference, the first fuzzy rule subset is activated to increase the proportional gain and derivative gain, decrease the integral gain, and generate a proportional directional valve opening adjustment command.

[0027] To address oil temperature interference, the second fuzzy rule subset is activated to reduce the proportional gain and differential gain, increase the integral gain, and generate a cooling water regulating valve opening adjustment command.

[0028] To address leakage interference, the third fuzzy rule subset is activated to maintain the proportional gain, significantly reduce the integral gain, increase the differential gain, and generate hydraulic pump displacement compensation commands.

[0029] Furthermore, in S6, the multi-interference coordination strategy specifically includes:

[0030] If the current problem is determined to be a single dominant interference type, the compensation command corresponding to that type will be directly output to its corresponding actuator.

[0031] If the current scenario is determined to be a complex one with multiple dominant interference types coexisting, then the compensation instructions for each interference type are coordinated and output according to the preset hybrid scheduling strategy.

[0032] The core of the hybrid scheduling strategy is to prioritize handling load interference, process leakage interference in parallel, and process oil temperature interference with a delay.

[0033] Furthermore, in S7, the process for triggering the exception protection includes:

[0034] The controller generates an alarm signal and controls the hydraulic pump displacement gradient to decrease until the speed deviation returns to within the tolerance threshold. If the slider speed deviation continues to exceed the limit, a shutdown alarm is triggered.

[0035] Furthermore, the generation of the proportional directional valve opening adjustment command includes calculating the corresponding opening adjustment amount according to the following formula:

[0036] ,in:

[0037] Δ 开度 This indicates the adjustment amount of the proportional directional valve opening.

[0038] K p K i K d To adapt fuzzy PID real-time control parameters to load disturbances,

[0039] ΔP is the pressure difference between the inlet and outlet ports of the main hydraulic cylinder, reflecting a feedforward signal indicating load changes.

[0040] K p ×Δp: Feedforward compensation based on load changes to improve system response speed;

[0041] K i ×∫Δv×dt: Integral compensation based on the cumulative amount of slider speed deviation to eliminate steady-state error;

[0042] K d ×d(Δv) / dt: Differential compensation based on the slider speed change trend, suppressing overshoot and enhancing stability.

[0043] Furthermore, the generation of the cooling water regulating valve opening adjustment command includes calculating the corresponding opening adjustment amount according to the following formula:

[0044] ,in,

[0045] Δ 冷却水 This indicates the adjustment amount of the cooling water regulating valve opening.

[0046] ΔT represents the oil temperature deviation.

[0047] K pt Indicates the temperature compensation proportional gain.

[0048] K it This represents the integral gain for temperature control.

[0049] ∫ΔT dt represents the historical cumulative temperature deviation, used to eliminate static errors.

[0050] Furthermore, the generation of the hydraulic pump displacement compensation command includes calculating the corresponding displacement adjustment amount according to the following formula:

[0051] ,in,

[0052] ΔQ 液压泵This indicates the adjustment amount of the hydraulic pump displacement.

[0053] Q 泄漏 Real-time leakage estimate based on state-space model.

[0054] K pq This indicates the leakage compensation ratio gain.

[0055] K iq Indicates the integral gain for leakage compensation.

[0056] ∫Q 泄漏 ×dt represents the total volume of oil that has been leaked.

[0057] Compared with existing technologies, the present invention provides a method for controlling the downward speed deviation of a hydraulic press slide, which has the following advantages:

[0058] 1. Achieved precise interference decoupling and identification: Through preset composite judgment rules, the system can distinguish between interference sources with completely different characteristics, such as load change, oil temperature drift, and internal leakage, in real time and automatically, solving the root cause problem of traditional control's "vague perception and unclear diagnosis".

[0059] 2. Achieved parameter self-adaptation and strategy specialization: Based on the type of disturbance, different subsets of fuzzy rules are dynamically activated, enabling the adaptive fuzzy PID real-time control parameters to have a "targeted" self-tuning capability. Simultaneously, the system adopts a "hybrid architecture combining adaptive and fixed parameters," optimizing control channels with vastly different dynamic characteristics. Adaptive parameters are used for the rapidly changing main speed control loop, while fixed parameters are used for the slowly changing temperature control loop and the trend-based leakage feedforward compensation channel, thus ensuring optimal global control performance.

[0060] 3. Achieved coordinated and conflict-free scheduling of instructions: Through a priority-based multi-interference coordination strategy, the actions of multiple actuators (such as load priority response, leakage parallel compensation, and oil temperature lag adjustment) can be coordinated in an orderly and conflict-free manner in complex interference scenarios, solving the problem of instruction coupling and oscillation in multivariable systems.

[0061] 4. Improve overall product quality: It ensures the accuracy of the slider's downward speed setting and the ability to resist dynamic disturbances, which is ultimately reflected in the consistency of workpiece dimensional tolerances, the uniformity of material forming structure and the improvement of surface quality, significantly reducing the scrap rate. It is especially suitable for precision stamping, forging and other fields with stringent precision requirements. Attached Figure Description

[0062] Figure 1 This is a schematic diagram of the workflow framework of the present invention;

[0063] Figure 2 This is a schematic diagram of the workflow of the present invention;

[0064] Figure 3 This is a schematic diagram of the system framework of the present invention. Detailed Implementation

[0065] 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 embodiments of the present invention, and not all embodiments. 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.

[0066] In this invention, unless otherwise specified, the term "system" refers to the intelligent control system for the slide speed of a hydraulic press using the control method of this invention. This intelligent control system, with a controller at its core, mainly includes: a hydraulic pump as the power source; an integrated main oil circuit control valve group and a main oil cylinder as the core actuators; a slide as the controlled object; a temperature control system for temperature control; and displacement, pressure, and temperature sensors for real-time status feedback.

[0067] Example 1, such as Figures 1-3 As shown, a method for controlling the downward speed deviation of a hydraulic press slide includes a data acquisition module, a processing module, an actuator, an alarm device, and a data recording module electrically connected to a controller. The controller integrates basic PID and adaptive fuzzy PID. The method is characterized by the following steps:

[0068] S1. Real-time acquisition of slider position, main cylinder inlet / outlet pressure and hydraulic oil temperature signals;

[0069] S2. Calculate the actual speed of the slider based on the slider position signal, and compare it with the preset target speed to obtain the speed deviation and the rate of change of speed deviation;

[0070] S3. If the speed deviation continues to exceed the preset tolerance threshold, it is determined that the current control accuracy is insufficient, and the system automatically switches from the basic PID control mode to the adaptive fuzzy PID control mode.

[0071] S4. In the adaptive fuzzy PID control mode, when the absolute value of the speed deviation is greater than the tolerance threshold, the current dominant disturbance type is determined based on the speed deviation, the rate of change of speed deviation and the pressure signal, according to the preset mapping rules; the dominant disturbance type includes load disturbance, oil temperature disturbance and leakage disturbance.

[0072] S5. Generate corresponding compensation instructions based on the determined dominant interference type;

[0073] S6. Based on the currently determined dominant interference type and the preset multi-interference coordination strategy, output the compensation command generated in S5 to the corresponding execution mechanism for execution;

[0074] S7. Closed-loop monitoring and status decision: Continuously monitor the speed deviation. If it returns to the tolerance threshold and remains stable, switch back to the basic PID mode. If it continues to exceed the limit, trigger the abnormal protection process. Otherwise, repeat steps S4 to S6.

[0075] In this embodiment, the hydraulic press can be a four-column hydraulic press, a frame hydraulic press, or other types of hydraulic presses. It also includes a hydraulic system and a control system, with the control system integrated in the electrical control cabinet. The hardware installation is performed first, referring to… Figure 3 The controller uses a PLC such as Siemens S7-1214C, which is installed in the electrical control cabinet. The PLC is connected to the workshop MES system and integrates basic PID and adaptive fuzzy PID.

[0076] The specific system architecture of this embodiment is as follows:

[0077] 1. Hydraulic power and actuation circuit

[0078] The hydraulic power unit is equipped with a hydraulic pump (a variable displacement pump with a displacement range of 0~120 L / min) to supply oil to the main hydraulic circuit system. The core of the hydraulic control is an integrated main hydraulic circuit control valve group, which is fixed on the hydraulic power unit and includes a proportional directional valve.

[0079] The proportional directional valve controls the direction and speed of the main cylinder's movement. Its integrated pressure compensator automatically maintains a constant valve port pressure difference, ensuring that the output flow is strictly proportional to the input control signal. This proactively eliminates the main interference of load fluctuations on flow at the hardware level, laying the foundation for high-precision speed closed-loop control. Its working oil circuit can be switched according to controller commands, allowing oil to flow to the main cylinder or be unloaded to the oil tank via a bypass to achieve different speed modes.

[0080] Temperature control system: Used to cool hydraulic oil. Its main component is a cooler connected in series on the hydraulic system's return oil line; a plate cooler can be selected. A cooling water regulating valve is installed on the cooler's inlet channel; an LX-500 proportional regulating valve can be selected. Based on the feedback signal from the temperature sensor, the controller outputs a control signal to the cooling water regulating valve, stabilizing the oil temperature by proportionally adjusting the cooling water flow rate.

[0081] System pressure proportional control valve (proportional relief valve): used to set and adjust the working pressure of the hydraulic system according to process requirements.

[0082] Safety protection circuit: A pilot-operated relief valve is independently installed at the hydraulic pump outlet to set the maximum working pressure of the entire hydraulic system and provide overload protection.

[0083] 2. Sensing and Detection System

[0084] To achieve closed-loop control, the control system is equipped with a data acquisition module, including:

[0085] Displacement sensor: Fixed on the crossbeam of the hydraulic press, aligned with the side of the slider (or the piston rod of the cylinder), used to detect the slider position in real time (its detection axis is parallel to the vertical movement trajectory of the slider, and the installation deviation is ≤0.5°), and to calculate the downward speed accordingly;

[0086] Pressure sensor: Installed in the inlet / outlet oil line of the main oil cylinder, the monitored pressure signal is used for real-time observation and compensation of load changes, and participates in system overload protection;

[0087] Temperature sensor: Installed in the return oil area of ​​the hydraulic oil tank to monitor the oil temperature.

[0088] 3. Electrical control and actuator

[0089] The control system (controller) is based on a Siemens S7-1214C PLC, and its input / output configuration is as follows:

[0090] Analog output module channels:

[0091] Channel 1: Outputs a 4~20mA signal to the control terminal of the hydraulic pump to control its start / stop and displacement adjustment;

[0092] Channel 2: Outputs a 0~10V signal to the proportional solenoid of the proportional directional valve to control its valve core opening (0-100% corresponds to 0-10V) to regulate the flow rate into the main cylinder;

[0093] Channel 3: Outputs a 0-10V signal to the cooling water regulating valve to control its opening.

[0094] Channel 4: Outputs a 0~10V signal to the proportional solenoid of the system pressure proportional control valve (proportional relief valve) to set the system working pressure (0-10V corresponds to 0 to the system's maximum safe pressure).

[0095] Digital output module:

[0096] Q0.0: Drives the DC24V indicator light;

[0097] Q0.1: Drives a DC24V buzzer; the indicator light and buzzer together form an audible and visual alarm device.

[0098] Analog input module:

[0099] Module 1: Connects to the displacement sensor, receives the displacement sensor signal, and uses it to provide feedback on the slider position;

[0100] Module 2: Connects to the pressure sensor, receives pressure sensor signals, and is used to monitor the pressure at the inlet / outlet of the main hydraulic cylinder;

[0101] Module 3: Connects to a temperature sensor, receives temperature sensor signals, and is used to monitor the hydraulic oil temperature.

[0102] The processing module, integrated within the controller, serves as the core of the system's intelligent decision-making and includes the following collaborative functional sub-modules:

[0103] Calculation module: Used to process sensor signals in real time and calculate the actual speed of the slider, speed deviation and its rate of change;

[0104] Control mode management module: used to automatically determine and switch between basic PID control mode and adaptive fuzzy PID control mode based on the speed deviation status;

[0105] Interference feature determination module: It has an embedded preset mapping rule library, which is used to execute the judgment logic of the three sets of composite conditions based on multi-source information such as speed, pressure, and temperature, so as to output the determination result of the dominant interference type.

[0106] Adaptive fuzzy PID algorithm module: used to activate the corresponding fuzzy rule subset based on the interference type determination result, and adjust the proportional, integral, and derivative gain parameters of the PID controller online;

[0107] Compensation instruction synthesis and scheduling module: It is used to calculate the compensation instructions corresponding to each actuator based on the adaptively tuned parameters or preset strategies, and coordinate and output them according to the hybrid scheduling strategy.

[0108] In this embodiment, the actuator mainly includes a proportional directional valve, a temperature control system, and a hydraulic pump.

[0109] 4. Data storage and monitoring

[0110] The memory (industrial-grade SD card) is installed in the SD card slot of the controller (PLC, Siemens S7-1214C) and is used to store process parameters and operating data. The process parameters include, but are not limited to: the target speed value (or target speed curve) of the slider descent process, algorithm parameters, and preset thresholds. The data recording module synchronously records the actual slider speed, the pressure of the main cylinder inlet / outlet, and the hydraulic oil temperature data and stores them in the memory.

[0111] The Human-Machine Interface (HMI) communicates with the PLC via Ethernet and is used for setting, downloading, monitoring, and displaying and analyzing process parameters and operating data.

[0112] The control system operates based on the aforementioned hardware: the controller (PLC, Siemens S7-1214C) acquires the slider displacement signal in real time, calculates the actual speed, compares it with the target speed, and generates a speed deviation signal. Based on this speed deviation signal and considering pressure and temperature feedback, the controller (integrating basic PID and adaptive fuzzy PID algorithms) determines the dominant disturbance type and immediately initiates a targeted compensation mechanism: a dedicated fuzzy PID parameter adjustment strategy is matched for each disturbance type, and corresponding physical compensation instructions are generated. When multiple disturbances occur simultaneously, the system outputs instructions in an orderly and coordinated manner according to a hybrid scheduling strategy of "load priority, leakage parallel, and oil temperature lag," avoiding control conflicts. Ultimately, stable and adaptive control of the slider's downward speed is achieved.

[0113] Example 2, continue to refer to Figures 1-2 In one embodiment, the target slider speed is first set to 10 mm / s, the sampling period is 10 ms, the slider speed deviation threshold is ±0.1 mm / s, and the target hydraulic oil temperature is 40°C via HMI.

[0114] During the slider's downward movement, displacement, pressure, and temperature sensors collect data on slider position, main cylinder inlet / outlet pressure, and hydraulic oil temperature, respectively. Median filtering and normalization are then applied to this data (this is existing technology). Median filtering effectively removes pulse noise caused by sensor vibration and electromagnetic interference, such as abrupt changes in displacement sensor values, by taking the median of the sampled data within the sliding window and replacing the original data at the window center. Normalization maps the original data of different physical quantities (such as pressure, temperature, and displacement) to a unified range of 0 to 1, preventing the controller from becoming overly sensitive to a particular parameter due to dimensional differences (such as pressure in MPa and temperature in °C).

[0115] In step S2, based on the position data of the slider at adjacent sampling times, the actual speed of the slider is calculated by the differential method in the calculation module; the actual speed is compared with the preset target speed to obtain the slider speed deviation; if the absolute value of the slider speed deviation is greater than the preset threshold, the slider speed deviation adjustment process is triggered, and the preset tolerance threshold is ±0.1mm / s.

[0116] S21, based on adjacent sampling times t-Δt and t, and slider positions s(t) and s(t-Δt), calculate the actual slider velocity V1 using the finite difference method. Where s(t) is the current preprocessing position of the slider, s(t-Δt) is the preprocessing position of the slider at the previous sampling time, and Δt represents the sampling period;

[0117] S22, calculate the slider speed deviation ΔV, ΔV=V1-V0, where V0 is the preset target speed;

[0118] The formula for calculating the rate of change of slider speed deviation ΔV´ is: , where Δv(t) represents the slider speed deviation at the current time t, Δv(t−Δt) represents the slider speed deviation at the previous sampling time, and Δt represents the sampling period.

[0119] In S3, the system switches between the basic PID and adaptive fuzzy PID algorithms based on the operating mode. The core principle is a dual-mode optimization mechanism implemented through tolerance threshold determination. Specifically, the system continuously monitors the absolute value of the slider speed deviation and compares it with a preset, uniform tolerance threshold (e.g., 0.1 mm / s). If the absolute value of the speed deviation continuously exceeds the tolerance threshold for a complete control cycle or a set short-term judgment window, the system determines that the current basic PID controller's adjustment capability is insufficient to maintain the required accuracy. It then automatically and seamlessly switches the operating mode to the adaptive fuzzy PID control mode via the control mode management module to activate more powerful interference suppression and parameter self-tuning functions.

[0120] Conversely, when the system is in adaptive fuzzy PID mode, if the speed deviation and its rate of change remain stable within the tolerance threshold for a preset relatively long stabilization time (i.e., the first stabilization period), it indicates that the system has returned to stability and the disturbance has been effectively compensated. At this time, to save controller computing resources, the system will automatically switch back to basic PID control mode until the next accuracy over-limit event is triggered.

[0121] In S4, the mapping rule is:

[0122] When the first set of composite conditions is met, the load interference is determined to be the dominant factor.

[0123] When the second set of composite conditions is met, oil temperature interference is determined to be the dominant factor.

[0124] When the third set of composite conditions is met, leakage interference is determined to be the dominant factor.

[0125] Each set of composite conditions is determined based on a comprehensive assessment of speed deviation, speed deviation change rate, duration, and key correlation parameters of the corresponding type.

[0126] The first set of composite conditions includes: the absolute value of the speed deviation is greater than the speed deviation threshold used for load disturbance judgment, the absolute value of the speed deviation change rate is greater than the first change rate threshold, the duration of the deviation and change rate exceeding the limit is less than the first duration threshold, and the pressure difference between the inlet and outlet is greater than the first pressure difference threshold or its change rate is greater than the first pressure change rate threshold.

[0127] The second set of composite conditions includes: the absolute value of the speed deviation is greater than the speed deviation threshold used for oil temperature interference determination, the absolute value of the speed deviation change rate is less than or equal to the second change rate threshold, the duration of the oil temperature interference is greater than or equal to the second duration threshold, and the oil temperature deviation is greater than the oil temperature deviation threshold or its change rate is greater than the oil temperature change rate threshold.

[0128] The third set of composite conditions includes: the absolute value of the velocity deviation is greater than the velocity deviation threshold used for leakage interference determination; the absolute value of the velocity deviation change rate is greater than the third change rate threshold and less than or equal to the fourth change rate threshold; the duration of the leakage interference is greater than or equal to the third duration threshold; and the leakage flow rate estimated based on the state-space model is greater than the rated leakage rate benchmark value.

[0129] Based on the determined dominant interference type, corresponding compensation commands are generated, ultimately producing corresponding compensation control setpoints for the proportional directional valve, cooler, and hydraulic pump. These are then converted into physical drive signals by the PLC, generating control signals for the proportional directional valve, cooler, and hydraulic pump, respectively. These control signals are transmitted through independent channels one, two, and three to control the hydraulic pump, proportional directional valve, and cooler, respectively.

[0130] In this embodiment, the state variables of the state-space model include: the actual speed of the slider, the pressure at the inlet / outlet of the main cylinder, the hydraulic oil temperature, and the estimated leakage.

[0131] The state-space model is established based on the physical equations of the hydraulic system and experimental data. In this embodiment, measurements from displacement and pressure sensors are received, and a built-in state observer is used to estimate the real-time leakage amount, which cannot be directly measured. This value is a dynamically changing quantity that accurately reflects the instantaneous leakage state inside the hydraulic system, providing a forward-looking compensation basis for the controller. The leakage estimate, along with the actual slider speed calculated by the differential method, the pressure difference between the main cylinder inlet and outlet, and the hydraulic oil temperature, are used as inputs to the adaptive fuzzy PID controller of this invention. The PID parameters are dynamically adjusted through a built-in fuzzy inference mechanism, thereby generating precise instructions for load, oil temperature, and leakage compensation. Finally, the PLC drives the actuator to achieve composite control combining feedforward and feedback.

[0132] The leakage estimate is calculated based on the relationship between the pressure difference at the inlet / outlet ports and the flow rate, which is derived from the real-time displacement of the hydraulic pump and the opening degree of the control valve. In a preferred embodiment of the invention, the control valve is a proportional directional valve, the opening of which is controlled by a current signal output from the controller to precisely regulate the flow rate to the main cylinder.

[0133] Because leakage cannot be directly measured by installing sensors, and internal leaks in seals and micro-leaks in pipelines are difficult to detect, a state-space model can be used to measure measurable variables such as the main cylinder inlet / outlet pressure, the actual slider speed V1, the hydraulic oil temperature, and Q. 泄漏额定 As input data, unmeasurable variables are deduced through state equations.

[0134] The specific implementation steps are as follows:

[0135] First, the following data are collected in real time: real-time hydraulic pump displacement, proportional directional valve opening K. V First, the pressure at the main cylinder inlet (P1), the pressure at the main cylinder outlet (P2), and the actual speed of the slide block (V1) are determined. Second, the combined flow relationship between the hydraulic pump and the proportional directional valve is derived, and the effective output flow rate (Q) of the hydraulic pump is calculated. P有效 The calculation formula is as follows: in, This refers to the theoretical displacement of the hydraulic pump. This refers to the volumetric efficiency of the hydraulic pump.

[0136] Then calculate the actual flow rate Q through the proportional directional valve. v The calculation formula is as follows: , where K v C represents the opening degree of the proportional directional valve. d A is the flow coefficient of the proportional directional valve. max This represents the maximum flow area of ​​the proportional directional valve orifice. P1-P2 is the hydraulic oil density, and P1-P2 is the pressure difference between the inlet and outlet ports of the main cylinder.

[0137] Next, calculate the effective working flow rate Q of the main hydraulic cylinder. work The calculation formula is: Where A is the piston area of ​​the main hydraulic cylinder and V1 is the actual speed of the slider.

[0138] Real-time leakage estimate Q 泄漏 The calculation formula is as follows: .

[0139] Based on the above embodiments, assuming the theoretical displacement of the hydraulic pump is 60 L / min, the volumetric efficiency of the hydraulic pump is 0.97, the opening degree of the proportional directional valve is 35%, the flow coefficient is 0.65, and the maximum flow area of ​​the valve port is 70 mm. 2 The density of the hydraulic oil is 860 kg / m³ 3 The main hydraulic cylinder inlet pressure P1 is 4 MPa, the main hydraulic cylinder return pressure P2 is 0.5 MPa, and the main hydraulic cylinder piston area is 12000 mm². 2 The actual slider speed is 45 mm / s, and the pressure correction factor is 0.015 MPa.

[0140] First, calculate the effective output flow rate of the hydraulic pump according to the formula. Substitute the values, Next, calculate the actual flow rate through the proportional directional valve according to the formula. Substitute the values,

[0141]

[0142] Next, calculate the effective working flow rate Q of the main hydraulic cylinder. work :

[0143]

[0144] Next, the estimated real-time leakage amount Q is calculated. 泄漏

[0145]

[0146] The controller uses this real-time leakage estimate as a key feedforward signal, directly converting it into a hydraulic pump displacement compensation command, which is output through channel one. By increasing the pump's output displacement, this leakage flow is actively and accurately compensated, thereby maintaining the stability of the main oil circuit's net flow.

[0147] In this embodiment, the actual speed of the slider when it contacts the material being pressed is compared with the preset target speed. The slider speed is then adjusted by the PLC. Assuming the slider moves steadily downwards, the basic PID precisely controls the hydraulic oil flow, resulting in minimal speed fluctuations. The sampling period is Δt = 0.01s, and the preset target speed is v0 = 10mm / s. After median filtering, noise reduction, and normalization, the data collected by the displacement sensor is processed for two consecutive sampling times. In the (n-1)th sampling, the sampling time is t - Δt; the slider position is 200mm, which is recorded as the previous position. In the nth sampling, the slider position is 200.1005mm at sampling time t. Substituting these values ​​into the formula, the actual speed is calculated as follows:

[0148]

[0149] Next, calculate the slider speed deviation Δv = v1 - v0, where v1 is the actual speed and v0 is the preset target speed;

[0150]

[0151] The calculated Δv is less than 0.1 mm / s, so the slider speed deviation adjustment process is not triggered.

[0152] When the system selects the basic PID algorithm, it uses pre-tuned adaptation parameters to precisely and efficiently control the actuator, continuously stabilizing the deviation between the actual slider speed and the preset target speed within a preset threshold. In this state, complex slider speed deviation adjustment processes do not need to be triggered; the basic PID independently maintains the system's stable operation, fully leveraging its advantages of simple structure, rapid response, and low computational resource consumption under normal or simple operating conditions.

[0153] Assuming a sampling period Δt = 0.01s, a preset target velocity v0 = 10mm / s, and the data collected by the displacement sensor after median filtering for noise reduction and normalization, at two consecutive sampling times, the (n-1)th sampling time is t - Δt; the slider position is 200mm, recorded as the previous position. At the nth sampling time t, the slider position is 200.12mm. Substituting these values ​​into the formula, the actual slider velocity is calculated as follows:

[0154]

[0155] Next, calculate the slider speed deviation Δv = v1 - v0.

[0156]

[0157] If the calculated result exceeds the preset threshold of 0.1 mm / s and persists for more than two control cycles, it is determined that the basic PID controller can no longer meet the control requirements, and the system automatically switches to the adaptive fuzzy PID controller. This triggers the slider speed deviation adjustment process, i.e., proceeding to step S4, where the current dominant disturbance type is determined based on preset mapping rules. The dominant disturbance types include load disturbance, oil temperature disturbance, and leakage disturbance.

[0158] The slider speed deviation adjustment process is as follows: First, by analyzing the slider speed deviation value and related parameters, including the main cylinder inlet / outlet pressure, hydraulic oil temperature, and estimated real-time hydraulic oil leakage, the applicable compensation type is determined. The specific steps are as follows:

[0159] Step 1: Extract feature parameters. Based on the sampling period, the feature parameters are collected as follows:

[0160] Slider speed deviation parameter, Δv = v1 - v0,

[0161] Pressure parameters, ΔP = P1 - P2, where ΔP represents the pressure difference, P1 represents the pressure at the main cylinder inlet, and P2 represents the pressure at the main cylinder return port. △P´ represents the rate of pressure change, and △t represents the sampling period.

[0162] Hydraulic oil temperature parameters △T represents the temperature deviation, where T is the actual temperature. 设定 To set the temperature, the rate of temperature change ;

[0163] Hydraulic oil real-time leakage estimation parameters, based on calculate.

[0164] Step 2: Establish the mapping rules between slider speed deviation characteristics and interference compensation types, and determine the dominant interference type through the interference characteristic determination module.

[0165] The determination follows a two-tiered logic: First, the system checks whether the absolute value of the current speed deviation has exceeded the tolerance threshold (0.1 mm / s in this embodiment). This step ensures that the subsequent adaptive fuzzy PID control, which has a higher computational cost, is only activated when the basic PID control shows insufficient accuracy. After confirming entry into the diagnostic procedure, the system further compares the current speed deviation, the rate of change of speed deviation, the duration of the specific state, and the corresponding key related parameters (main cylinder inlet / outlet pressure, hydraulic oil temperature, and estimated real-time hydraulic oil leakage) with preset mapping rules to determine the dominant disturbance type.

[0166] It is worth noting that each of the following sets of composite conditions first requires the speed deviation to exceed a basic threshold, which in this embodiment is the same as the tolerance threshold. This ensures that any identified dominant disturbance is a significant factor that truly causes the system performance to exceed the allowable range. The specific determination logic is as follows:

[0167] A1. Load interference judgment conditions (i.e., the first set of composite conditions).

[0168] Inlet / outlet oil pressure difference ,

[0169] Where Δv is the absolute value of the slider speed deviation.

[0170] Δv´ is the absolute value of the rate of change of the slider speed deviation.

[0171] ΔP is the pressure difference between the inlet and outlet oil ports.

[0172] ΔP´ is the rate of change of pressure.

[0173] t 1持续 The duration of the deviation and rate of change exceeding the limit;

[0174] In this example, the speed deviation threshold for load interference determination is set to 0.1 mm / s;

[0175] The first rate of change threshold is 5 mm / s².

[0176] The first duration threshold is 2 seconds;

[0177] The first pressure difference threshold is 1.2 MPa;

[0178] The first pressure change rate threshold is 0.3 MPa / s.

[0179] A2. Oil temperature interference judgment conditions (i.e., the second set of composite conditions).

[0180] ,

[0181] Oil temperature deviation And the rate of temperature change ,

[0182] Where ΔT is the oil temperature deviation.

[0183] ΔT´ is the rate of temperature change.

[0184] t 2持续 The duration of oil temperature disturbance;

[0185] In this example, the speed deviation threshold for oil temperature interference determination is set to 0.1 mm / s;

[0186] The second rate of change threshold is 1.5 mm / s².

[0187] The second duration threshold is 15 seconds;

[0188] The oil temperature deviation threshold is 1.5℃;

[0189] The threshold for oil temperature change rate is 0.05℃ / s.

[0190] A3. Leakage interference judgment conditions (i.e., the third set of composite conditions).

[0191] , ,

[0192] Among them, t 3持续 Q represents the duration of the leakage interference. 泄漏额定 Q is the baseline value for rated leakage. 泄漏额定 Take 0.5 L / min;

[0193] In this example, the velocity deviation threshold for determining leakage interference is 0.1 mm / s;

[0194] The third rate of change threshold is 1.5 mm / s².

[0195] The fourth rate of change threshold is 4 mm / s².

[0196] The third duration threshold is 10 seconds.

[0197] Example 3: Based on the determined dominant interference type, a corresponding compensation instruction is generated. The core of this stage is the coordination between the adaptive fuzzy PID parameter adjustment driven by the dominant interference type and the dedicated control channel, i.e., proceeding to step S5. The specific implementation process is as follows:

[0198] S51. Configuration of Fuzzy Rule Subsets

[0199] The controller has three pre-stored independent subsets of fuzzy rules, corresponding to load disturbance, oil disturbance temperature, and leakage disturbance, respectively. Each subset of fuzzy rules contains a complete set of "if-then" rules, whose inputs are the current speed deviation (E) and the rate of change of speed deviation (EC), and whose output is the adjustment amount of the PID parameters (proportional gain adjustment ΔK). p Integral gain adjustment ΔK i Differential gain adjustment ΔK d ).

[0200] The first subset of fuzzy rules (for load disturbances): its core strategy is rapid response and oscillation suppression. A typical rule is: "If the velocity deviation (E) is 'positive large' and the rate of change of velocity deviation (EC) is 'negative large,' then the proportional gain adjustment ΔK..." p For 'positive', the integral gain adjustment ΔK i For 'negative neutral', the differential gain adjustment ΔK d "To be 'center'" means, in physical terms, that by increasing the proportional gain (K... p To quickly correct bias while reducing integral gain (K) i To prevent integral saturation and increase the differential gain (K) d This is to suppress overshoot and enhance system stability.

[0201] The second fuzzy rule subset (for oil temperature interference): its core strategy is smooth adjustment and elimination of steady-state error. A typical rule is: "If the speed deviation (E) is 'positive small' and the rate of change of speed deviation (EC) is 'zero,' then the proportional gain adjustment ΔK..." p "When the integral gain adjustment ΔKi is 'small negative', the differential gain adjustment ΔKd is 'small positive'." This means that when there is a small and stable speed lag (usually caused by slow changes in oil temperature), the proportional gain (K) is slightly reduced. p ) and differential gain (K d To avoid overreacting to slow disturbances and high-frequency oscillations, while appropriately enhancing the integral gain (K). i This function aims to steadily eliminate steady-state errors caused by oil temperature drift.

[0202] The third subset of fuzzy rules (targeting leakage interference): Its core strategy is to prevent integral saturation and maintain damping. A typical rule is: "If E is 'positive middle' and EC is 'positive small', then ΔK..." p ΔK is 'zero' i For 'negative large', ΔK d "For 'positive small'." Its physical meaning is: when the velocity deviation is moderate and slowly increases due to continuous leakage, the proportional gain (K) is maintained. p To avoid over-responding to trend drift, the integral gain (K) is significantly reduced. i This is to prevent the ineffective and harmful accumulation of persistent bias (i.e., to prevent the integral gain (K) from being absorbed). i ) saturation), and slightly enhance the differential gain (K) d To maintain sufficient system damping and improve anti-interference capability.

[0203] S52. Fuzzy rule subset activation and online tuning of real-time control parameters

[0204] The system's final execution relies on the configured control channels, which include the main speed control loop, temperature control loop, and feedforward compensation channel. Based on the dominant disturbance type determined by S4, the system activates the corresponding fuzzy rule subset. The goal of all fuzzy rule subsets is to adjust the adaptive fuzzy PID parameters of the main speed control loop. The precise proportional gain adjustment ΔK is obtained through fuzzy inference and defuzzification calculations. p Integral gain adjustment ΔK i Differential gain adjustment ΔK d Based on this, the adaptive fuzzy PID real-time control parameters of the main speed control loop are updated.

[0205] K p =K p0 +ΔK p

[0206] K i =K i0 +ΔK i

[0207] K d =K d0 +ΔK d

[0208] At the same time, the system will trigger the corresponding temperature control loop or feedforward compensation channel in parallel according to the dominant interference type to complete the compensation task in a coordinated manner.

[0209] S53. Specific Calculation of Control Channel Coordination Triggering and Compensation Commands

[0210] To achieve complete suppression of interference, the system employs a collaborative architecture that combines adaptive optimization of the main speed control loop with parallel operation of the temperature control loop or feedforward compensation channel. Specifically, the system triggers corresponding control channel combinations based on the type of interference:

[0211] S531, Load disturbance, triggers only the main speed control loop. This loop uses the adaptive fuzzy PID real-time control parameters updated in S52, and its output is the proportional directional valve opening adjustment command. The calculation formula is:

[0212] ,in:

[0213] K p K i K d These are the real-time control parameters after online tuning of the adaptive fuzzy PID algorithm in S52;

[0214] ΔP is the pressure difference between the inlet and outlet ports of the main hydraulic cylinder, reflecting a feedforward signal indicating load changes.

[0215] ΔP is the pressure difference between the inlet and outlet ports of the main hydraulic cylinder, reflecting a feedforward signal indicating load changes.

[0216] K p ×Δp: Feedforward compensation based on load changes to improve system response speed;

[0217] K i ×∫Δv×dt: Integral compensation based on the cumulative amount of slider speed deviation to eliminate steady-state error;

[0218] K d × d(Δv) / dt: Differential compensation based on the slider speed change trend, suppressing overshoot and enhancing stability.

[0219] S532, leakage interference, while optimizing the main speed control loop, triggers an independent feedforward compensation channel in parallel. This channel uses a preset fixed gain parameter (K). pq K iq Its output is the hydraulic pump displacement compensation command, and the calculation formula is:

[0220] ,in,

[0221] ΔQ 液压泵 This indicates the adjustment amount of the hydraulic pump displacement.

[0222] Q 泄漏 Real-time leakage estimate based on state-space model.

[0223] K pq This indicates the leakage compensation ratio gain.

[0224] Kiq Indicates the integral gain for leakage compensation.

[0225] ∫Q 泄漏 ×dt represents the total volume of oil that has been leaked.

[0226] Leakage compensation proportional gain K pq and leakage compensation integral gain K iq The two sets of preset fixed gain parameters are fixed optimal values ​​obtained through system calibration, or remain unchanged after manual tuning during the debugging phase. The tuning objective is to ensure response speed while avoiding overcompensation for leakage.

[0227] S533, oil temperature interference: While optimizing the main speed control loop, an independent temperature control loop is triggered in parallel. This loop uses preset fixed parameters (K). pq K it Its output is the cooling water regulating valve opening adjustment command, and the calculation formula is:

[0228] ,in,

[0229] Δ 冷却水 This indicates the adjustment amount of the cooling water regulating valve opening.

[0230] ΔT represents the oil temperature deviation.

[0231] K pt Indicates the temperature compensation proportional gain.

[0232] K it Indicates the integral gain for temperature control;

[0233] ∫ΔT dt represents the historical cumulative temperature deviation, used to eliminate static errors;

[0234] Given the large inertia and slow time-varying nature of temperature changes, the fixed parameter adopts integral dominance (i.e., the integral gain K of temperature control). it Much greater than the temperature compensation proportional gain K pt The PID strategy with temperature compensation proportional gain K pt Integral gain K for temperature control it A fixed-value setting method based on engineering experience is adopted. Specific values ​​are determined through step response testing and steady-state accuracy calibration during system commissioning and are maintained constant during subsequent operation. This ensures that the oil temperature reaches the set point smoothly without overshoot.

[0235] S54, Compensation Command Mapping

[0236] Based on the dominant interference type determined in S4, the system maps it to the corresponding control channel to generate compensation commands:

[0237] S541, Load Disturbance: The compensation command originates from the main speed control loop. The PID parameters of this loop (K...) p , K i , K d The speed is adjusted online in real time by an adaptive fuzzy PID algorithm. The compensation command (i.e., the proportional directional valve opening command) is equal to the output value of the speed PID controller.

[0238] S542, Oil Temperature Interference: The compensation command originates from an independent temperature control loop. This loop uses preset, fixed PID parameters (K... pt , K it ), and adopts an integral-dominated strategy (K it K pt The compensation command (i.e., the cooling water regulating valve opening command) is calculated by the temperature PID controller with fixed parameters based on the oil temperature deviation ΔT.

[0239] S543. Regarding leakage interference: The compensation command originates from the feedforward compensation channel. This channel uses a preset, fixed feedforward compensation gain (K). pq , K iq The compensation command (i.e., the hydraulic pump displacement compensation amount) is calculated based on the hydraulic pump displacement compensation adjustment calculation formula.

[0240] In Example 4, after generating the compensation command, the system proceeds to step S6. Specifically, this step includes two sub-processes: command synthesis and coordinated output.

[0241] S61, Coordination of Compensation Instructions

[0242] Based on the compensation command calculation formulas corresponding to each dominant interference type determined by S5, and combined with the data from the acquisition module, the preliminary compensation command values ​​for the proportional directional valve, cooling water regulating valve and hydraulic pump are calculated respectively.

[0243] S62, Output based on multi-interference coordination strategy

[0244] Based on the dominant interference type determined by S4, the PLC follows the following multi-interference coordination strategy to compensate for the initial instruction coordination of the instruction synthesis and scheduling module after S61 synthesis, and then outputs the final instruction:

[0245] 1. In a single interference scenario, if only one type of interference compensation is met, then the corresponding compensation will be activated:

[0246] If the load disturbance characteristics are met, load compensation is performed, and the PLC outputs a command to adjust the opening of the pressure compensation valve.

[0247] Based on the characteristics of oil temperature interference, oil temperature compensation is performed, and the PLC outputs a command to adjust the opening of the cooling water regulating valve.

[0248] If the leakage interference characteristics are met, leakage compensation is executed, and the PLC outputs a hydraulic pump displacement compensation adjustment command; for every 0.1L / min exceeding the estimated leakage value, the displacement increases by 2%.

[0249] 2. In scenarios with combined disturbances, the control system coordinates the different physical characteristics and dynamic response requirements of load, leakage, and oil temperature disturbances using a "priority-based parallel-serial hybrid scheduling strategy." The core principle is: prioritize handling load disturbances, process leakage disturbances in parallel, and handle oil temperature disturbances with a delay. Specifically:

[0250] 21. Load Disturbance – Highest Priority, Immediate Execution: Load disturbance compensation commands have the highest priority. Once detected, the corresponding proportional directional valve opening adjustment command will be generated and output immediately to ensure instantaneous response to sudden load changes;

[0251] 22. Leakage Interference – Parallel Generation and Dynamic Coordination: Leakage compensation commands and load commands are generated in parallel. To avoid flow command conflicts, the final output amplitude will be dynamically weighted and coordinated according to the severity of the current load interference (for example, when the load changes drastically, the instantaneous adjustment amplitude of leakage compensation will be appropriately reduced) before being output to the hydraulic pump;

[0252] 23. Oil Temperature Disturbance – Delayed Triggering and Decoupled Output: Given the large inertia and slow time-varying nature of temperature changes, the oil temperature disturbance compensation command adopts a delayed output strategy. Only after the rapid response process of the load disturbance has started, a preset time delay (e.g., 100ms) is applied before the command is output to the cooling water regulating valve. This decouples the dynamic coupling between the fast speed loop and the slow temperature loop, preventing low-frequency oscillations in the control system.

[0253] For example, if both load interference and oil temperature interference are detected simultaneously, load compensation will be initiated first, followed by oil temperature compensation 100ms later.

[0254] Finally, the actuator executes the compensation command. When the actuator executes the command, certain constraints are imposed. For example, for the pressure compensation valve, the upper limit of the opening adjustment is ≤50% (to avoid sudden pressure changes caused by the valve opening being fully open); for the hydraulic pump, the upper limit of the displacement adjustment is ≤20% (to avoid hydraulic pump overload); for the temperature control system, the upper limit of the power adjustment is ≤80% (to avoid insufficient or excessive cooling).

[0255] Based on the above embodiment, assuming the hydraulic press slide moves downwards at v0 = 10 mm / s, the main cylinder inlet pressure P1 is 7 MPa, and the main cylinder return pressure P2 is 5 MPa, the workpiece suddenly jams during stamping, triggering a sudden load change. The jamming time is 0.2 s. The actual slide speed is calculated to be 8 mm / s using the differential method. The calculated parameters are shown in the table below.

[0256] parameter Calculated / Measured Values Comparison of judgment conditions Does it meet the requirements? Slider speed deviation |Δv| 2mm / s >0.1mm / s yes Rate of change of velocity |Δv′| <![CDATA[10mm / s 2 ]]> <![CDATA[>5mm / s 2 ]]> yes <![CDATA[Duration t 1持续 > 0.2s ＜2s yes Pressure difference ΔP ΔP=6MPa >1.2MPa yes Pressure change rate ΔP′ 10MPa / s >0.5MPa / s yes

[0257] Based on the above load interference judgment conditions, all conditions are met, and it is judged as load interference. Load compensation is executed, and the PLC outputs the proportional directional valve opening adjustment amount. For every 1MPa pressure difference, the opening increases by 5%.

[0258] The hydraulic press ran continuously for 15 minutes at an ambient temperature of 30℃, with the oil temperature rising from 40℃ to 55℃. The actual speed was 9.5 mm / s. The monitored parameters are shown in the table below.

[0259] parameter Calculated / Measured Values Comparison of judgment conditions Does it meet the requirements? Slider speed deviation |Δv| 0.5mm / s >0.1mm / s yes Rate of change of velocity |Δv′| 0.00056mm / s2 <![CDATA[≤1.5mm / s 2 ]]> yes <![CDATA[Duration t 2持续 > 15min = 900s ≥15s yes Oil temperature deviation ΔT 55-40=15℃ ＞1.5℃ yes Temperature change rate ΔT′ 0.15℃ / s ＞0.05℃ / s yes

[0260] Based on the above load interference judgment conditions, all conditions meet the oil temperature interference characteristics, and it is judged as oil temperature interference. Oil temperature compensation is executed, and the PLC outputs the cooling water regulating valve opening command. For every 1°C increase, the opening increases by 10%; and the cooling pump is started simultaneously.

[0261] If the seal ages suddenly, and the estimated leakage rate gradually increases from the rated 0.5 L / min to 0.7 L / min within 1 second, causing the slider speed to drop sharply from 10 mm / s to 7 mm / s, and the time from the onset of leakage to stabilization is 7 seconds, the parameters are as follows.

[0262] parameter Calculated / Measured Values Comparison of judgment conditions Does it meet the requirements? Slider speed deviation |Δv| 3mm / s >0.1mm / s yes Rate of change of velocity |Δv′| <![CDATA[3mm / s 2 (Changes within 5 seconds) <![CDATA[2<Δv′≤4mm / s 2 ]]> yes <![CDATA[Duration t 3持续 > 7 seconds (time from the onset of a leak to its stabilization) 3≤t<15s yes <![CDATA[Real-time estimated leakage volume Q 泄漏 > 0.7L / min >1.2 × 0.5 = 0.6 L / min yes

[0263] If all conditions meet the leakage interference characteristics, the leakage interference is determined to be leakage interference based on the above leakage interference judgment conditions. Leakage compensation is then performed, and the PLC outputs the hydraulic pump displacement compensation amount. For every 0.1L / min exceeding the estimated leakage amount, the displacement increases by 2%.

[0264] Example 5: During the continuous operation of the hydraulic press, real-time monitoring is achieved through closed-loop monitoring and status decision-making in step S7, as detailed below:

[0265] S71. The controller continuously monitors the actual speed of the slider, calculates its deviation from the target speed, and compares the absolute value of the deviation with the tolerance threshold (±0.1 mm / s):

[0266] S711. Steady-state determination: If the slider speed deviation remains stable within the tolerance threshold for the first stable time (e.g., 5s), the system is determined to have returned to steady state and will automatically switch from adaptive fuzzy PID control mode back to basic PID control mode to save computing resources.

[0267] S712, Abnormal State Judgment: If the slider speed deviation continues to exceed the tolerance threshold and reaches the first abnormal duration (e.g., 3s), the system is determined to be in an abnormal state and the abnormal protection process is triggered.

[0268] S713. Continuous adjustment determination: If the current state does not meet the steady state of S71 or the abnormal state of S72, the system is determined to still need compensation adjustment, and the system automatically repeats steps S4 to S6.

[0269] S72. In S712, the exception protection process includes:

[0270] The controller generates an alarm signal, and the PLC outputs a current signal gradient to reduce the hydraulic pump displacement until the speed deviation returns to within the tolerance threshold, after which it automatically resets.

[0271] The alarm device is activated: the buzzer sounds intermittently, the red light flashes, the HMI interface pops up a slider speed deviation timeout warning box (displaying the duration and current speed), and pushes an alarm code to the workshop MES system, marked as "slider speed deviation control abnormal".

[0272] When the speed deviation returns to within the tolerance threshold, the system stops unloading and automatically resets: the indicator light turns green, the buzzer stops, and the system returns to silence.

[0273] S73, Data Logging and Fault Tracing

[0274] When an alarm is triggered, the data logging module synchronously records the following real-time parameters:

[0275] Actual slider speed, main cylinder inlet / outlet pressure, hydraulic oil temperature,

[0276] The data is named with alarm codes and timestamps and stored in the PLC's built-in FRAM memory (industrial-grade SD card) for fault diagnosis and analysis.

[0277] The recorded data can serve as the basis for determining the dominant interference type in reverse matching S4, assisting in subsequent diagnosis.

[0278] S74, Critical Fault Handling

[0279] When the speed deviation continues to exceed the limit (e.g., 3 seconds), the system will start calculating the trend of the slider speed deviation while initiating load reduction. If the average or instantaneous value of the slider speed deviation continues to increase in the following time (e.g., 2 seconds), it indicates that the fault is worsening. The system will trigger a shutdown alarm, at which point manual intervention is required for maintenance.

[0280] S75, Closed-loop continuous operation

[0281] The entire feedback adjustment process is carried out continuously during operation to ensure a stable downward speed of the slider, thereby guaranteeing the quality of product processing.

[0282] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for controlling the downward speed deviation of a hydraulic press slide, comprising a data acquisition module, a processing module, an actuator, an alarm device, and a data recording module electrically connected to a controller, wherein the controller integrates basic PID and adaptive fuzzy PID, characterized in that, Includes the following steps: S1. Real-time acquisition of slider position, main cylinder inlet / outlet pressure and hydraulic oil temperature signals; S2. Calculate the actual speed of the slider based on the slider position signal, and compare it with the preset target speed to obtain the speed deviation and the rate of change of speed deviation; S3. If the speed deviation continues to exceed the preset tolerance threshold, it is determined that the current control accuracy is insufficient, and the system automatically switches from the basic PID control mode to the adaptive fuzzy PID control mode. S4. In the adaptive fuzzy PID control mode, when the absolute value of the speed deviation is greater than the tolerance threshold, the current dominant disturbance type is determined based on the speed deviation, the rate of change of speed deviation and the pressure signal, according to the preset mapping rules; the dominant disturbance type includes load disturbance, oil temperature disturbance and leakage disturbance. S5. Generate corresponding compensation instructions based on the determined dominant interference type; S6. Based on the currently determined dominant interference type and the preset multi-interference coordination strategy, output the compensation command generated in S5 to the corresponding execution mechanism for execution; S7. Closed-loop monitoring and status decision: Continuously monitor the speed deviation. If it returns to the tolerance threshold and remains stable, switch back to the basic PID mode. If it continues to exceed the limit, the exception protection process is triggered; otherwise, repeat steps S4 to S6. In step S4, the mapping rule is as follows: When the first set of composite conditions is met, the load interference is determined to be the dominant factor. When the second set of composite conditions is met, oil temperature interference is determined to be the dominant factor. When the third set of composite conditions is met, leakage interference is determined to be the dominant factor. Each set of composite conditions is determined based on a comprehensive assessment of speed deviation, speed deviation change rate, duration, and key correlation parameters of the corresponding type. The first set of composite conditions includes: the absolute value of the speed deviation is greater than the first speed deviation threshold, the absolute value of the speed deviation change rate is greater than the first change rate threshold, the duration of the deviation and change rate exceeding the limit is less than the first duration threshold, and the pressure difference between the inlet and outlet is greater than the first pressure difference threshold or its change rate is greater than the first pressure change rate threshold. The second set of composite conditions includes: the absolute value of the speed deviation is greater than the second speed deviation threshold, the absolute value of the speed deviation change rate is less than or equal to the second change rate threshold, the duration of the state is greater than or equal to the second duration threshold, and the oil temperature deviation is greater than the oil temperature deviation threshold or its change rate is greater than the oil temperature change rate threshold. The third set of composite conditions includes: the absolute value of the speed deviation is greater than the third speed deviation threshold, the absolute value of the speed deviation change rate is greater than the third change rate threshold and less than or equal to the fourth change rate threshold, the duration of the state is greater than or equal to the third duration threshold, and the leakage flow estimated based on the state space model is greater than the rated leakage reference value.

2. The method according to claim 1, characterized in that, The state variables of the state-space model include: actual slider speed, main cylinder inlet / outlet pressure, hydraulic oil temperature, and estimated leakage.

3. The method according to claim 1, characterized in that, Based on the dominant interference type, the corresponding fuzzy rule subset is activated, the parameters of the adaptive fuzzy PID controller are adjusted, and physical execution instructions are generated; wherein, To address load interference, the first fuzzy rule subset is activated to increase the proportional gain and derivative gain, decrease the integral gain, and generate a proportional directional valve opening adjustment command. To address oil temperature interference, the second fuzzy rule subset is activated to reduce the proportional gain and differential gain, increase the integral gain, and generate a cooling water regulating valve opening adjustment command. To address leakage interference, the third fuzzy rule subset is activated to maintain the proportional gain, significantly reduce the integral gain, increase the differential gain, and generate hydraulic pump displacement compensation commands.

4. The method according to claim 1, characterized in that, In S6, the multi-interference coordination strategy specifically includes: If the current problem is determined to be a single dominant interference type, the compensation command corresponding to that type will be directly output to its corresponding actuator. If the current scenario is determined to be a complex one with multiple dominant interference types coexisting, then the compensation instructions for each interference type are coordinated and output according to the preset hybrid scheduling strategy. The core of the hybrid scheduling strategy is to prioritize handling load interference, process leakage interference in parallel, and process oil temperature interference with a delay.

5. The method according to claim 1, characterized in that, In step S7, triggering the exception protection process includes: The controller generates an alarm signal and controls the hydraulic pump displacement gradient to decrease until the speed deviation returns to within the tolerance threshold. If the slider speed deviation continues to exceed the limit, a shutdown alarm is triggered.

6. The method according to claim 3, characterized in that, The generation of the proportional directional valve opening adjustment command includes calculating the corresponding opening adjustment amount according to the following formula: ,in: Δ 开度 This indicates the adjustment amount of the proportional directional valve opening. K p K i K d This indicates the parameters for adaptive fuzzy PID real-time control in response to load disturbances. ΔP represents the pressure difference between the inlet and outlet ports of the main hydraulic cylinder, reflecting a feedforward signal indicating load changes. K p ×Δp: Represents feedforward compensation based on load changes to improve system response speed; K i ×∫Δv×dt: represents integral compensation based on the cumulative amount of slider speed deviation, eliminating steady-state error; K d ×d(Δv) / dt: This represents the differential compensation based on the trend of slider speed change, which suppresses overshoot and enhances stability.

7. The method according to claim 3, characterized in that, The generation of the cooling water regulating valve opening adjustment command includes calculating the corresponding opening adjustment amount according to the following formula: ,in, Δ 冷却水 This indicates the adjustment amount of the cooling water regulating valve opening. ΔT represents the oil temperature deviation. K pt Indicates the temperature compensation proportional gain. K it This represents the integral gain for temperature control. ∫ΔTdt represents the historical cumulative temperature deviation, used to eliminate static errors.

8. The method according to claim 3, characterized in that, The generation of the hydraulic pump displacement compensation command includes calculating the corresponding displacement adjustment amount according to the following formula: ,in, ΔQ 液压泵 This indicates the adjustment amount of the hydraulic pump displacement. Q 泄漏 Real-time leakage estimate based on state-space model. K pq This indicates the leakage compensation ratio gain. K iq This represents the integral gain for leakage compensation. ∫Q 泄漏 ×dt represents the total volume of oil that has been leaked.

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