CN109488654B - Displacement control method of electro-hydraulic actuator - Google Patents

Displacement control method of electro-hydraulic actuator Download PDF

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CN109488654B
CN109488654B CN201811554219.0A CN201811554219A CN109488654B CN 109488654 B CN109488654 B CN 109488654B CN 201811554219 A CN201811554219 A CN 201811554219A CN 109488654 B CN109488654 B CN 109488654B
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displacement
electro
hydraulic actuator
control
temperature
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CN109488654A (en
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田中山
井健
赖少川
董珊珊
杨昌群
张书荣
刘维国
徐中节
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China Petroleum and Chemical Corp
Xian Aerospace Propulsion Institute
China Oil and Gas Pipeline Network Corp
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China Petroleum and Chemical Corp
Xian Aerospace Propulsion Institute
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B13/00—Details of servomotor systems ; Valves for servomotor systems
    • F15B13/16—Special measures for feedback, e.g. by a follow-up device
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B21/00—Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
    • F15B21/08—Servomotor systems incorporating electrically operated control means
    • F15B21/087—Control strategy, e.g. with block diagram
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/61—Secondary circuits
    • F15B2211/613—Feeding circuits

Abstract

The invention discloses a displacement control method of an electro-hydraulic actuator, which adopts a segmented PID closed-loop control method to indirectly control the displacement of an output shaft of a hydraulic cylinder in the electro-hydraulic actuator, takes the displacement of the output shaft in the hydraulic cylinder collected by a displacement sensor as a feedback quantity to participate in closed-loop control, controls the output execution quantity to be the rotating speed and the steering direction of a servo motor, and compensates the integral temperature drift of the electro-hydraulic actuator by using a temperature compensation method; the control efficiency of the control method is improved, the control precision of the control method is improved, errors caused by temperature drift are eliminated, and the control precision of the electro-hydraulic actuator under the multi-load working condition is met.

Description

Displacement control method of electro-hydraulic actuator
Technical Field
The invention relates to a control method of an electro-hydraulic control device, in particular to a displacement control method of an electro-hydraulic actuator.
Background
The electro-hydraulic actuator is a direct-drive electro-hydraulic servo system, also called a valveless servo control system, and controls the displacement, the speed and the movement direction of an output shaft in a hydraulic cylinder by controlling the rotating speed and the steering of an alternating current servo motor, thereby realizing the movement control with high thrust and high speed. The control algorithms in some domestic products mostly adopt conventional PID control, fuzzy PID algorithm and the like, and the output quantity of the used position sensor is basically analog quantity; the high precision of the REXA Xpac actuator from KOSO corporation, usa is based on a flow matching system with a pump driving a hydraulic cylinder and once the specified position is reached, the motor is stopped (locked in place).
At present, the electro-hydraulic actuator system has various operating conditions, cannot meet the control precision requirement for a wide temperature range (-20 ℃ to +50 ℃) and a wide load range (-45000N to +45000N), and particularly has certain influence on the system when the electro-hydraulic actuator normally works and the environmental temperature changes in the range of-20 ℃ to +50 ℃, so that the system precision of the electro-hydraulic actuator is influenced; the product uses the operating mode many, when the load changes in the range of-45000N- +45000N, under the no-load and heavy load condition, influence difference to the system is great, when the actuator is under the no-load and ± 45000N load condition separately, the system works normally, when approaching the target position, according to PID algorithm, the output motor speed is the same, and under different loads, the gear pump efficiency is different, therefore the actuator movement speed that the same motor speed can realize is different, so at a certain time of system control cycle, the speed may appear when heavy load this speed is not enough to impel the actuator to move, the too big system of speed appears overshoot oscillation phenomenon when the no-load.
Disclosure of Invention
The invention aims to provide a displacement control method of an electro-hydraulic actuator, which is used for solving the problems of low control efficiency, low control precision, low temperature application range and the like of the displacement control method of the electro-hydraulic actuator in the prior art.
In order to realize the task, the invention adopts the following technical scheme:
a displacement control method of an electro-hydraulic actuator is used for controlling the execution quantity of the electro-hydraulic actuator according to a control signal of a field control host, wherein the execution quantity comprises the rotating speed and the steering direction of a servo motor in the electro-hydraulic actuator, and the control method is executed according to the following steps:
step 1, initializing closed-loop control parameters, wherein the closed-loop control parameters comprise control precision and have the unit of mm; setting a response requirement parameter with the unit of mm;
step 2, judging whether a control cycle is reached currently, if so, executing step 3, otherwise, executing step 2, wherein the control cycle is a clock cycle of an electro-hydraulic actuator control system, and the unit is ms;
step 3, collecting a control signal and a feedback signal, wherein the control signal is a control displacement sent by a field control host, and the feedback signal is a feedback displacement of an actuating mechanism in the electro-hydraulic actuator;
step 4, calculating the absolute value of the difference between the feedback displacement and the control displacement, if the absolute value of the difference is greater than the response requirement parameter, executing step 5, otherwise, returning to step 2;
step 5, if the absolute value of the difference is less than or equal to the control precision, stopping the servo motor; if the absolute value of the difference is greater than the control precision, executing the step 6;
step 6, if the absolute value of the difference is greater than the threshold, executing step 7, and if the absolute value of the difference is less than or equal to the threshold, executing step 8;
step 7, setting a first PID control parameter, wherein the first PID control parameter comprises Kp, Ki and Kd, and executing step 9;
step 8, setting a second PID control parameter, wherein the second PID control parameter comprises Kp ', Ki ' and Kd ', and executing step 9;
step 9, obtaining a control quantity by using a PID control method according to the first PID control parameter or the second PID control parameter, wherein the control quantity is the displacement of an actuating mechanism in the electro-hydraulic actuator;
step 10, converting the control quantity into an execution quantity;
and 11, controlling the action of an actuating mechanism of the electro-hydraulic actuator according to the actuating quantity, and returning to the step 2.
Further, when a feedback signal is collected, the feedback displacement is corrected by using a temperature compensation method.
Further, the temperature compensation method adopts a formula II to obtain the compensated feedback displacement P 'under the temperature value of the electro-hydraulic actuator when the feedback displacement is collected in the step 3'xThe unit is mm, wherein adopt displacement sensor to gather the feedback displacement volume:
Figure BDA0001911423960000031
wherein, PxThe displacement is actually acquired at the temperature of the electro-hydraulic actuator and is in mm;
ΔLlthe difference value between the displacement collected at any temperature and the displacement collected at normal temperature when the actual displacement is the zero position of the electro-hydraulic actuator,
Figure BDA0001911423960000041
wherein L isThThe difference value between the collected displacement and the collected displacement at normal temperature is measured in mm and L when the electro-hydraulic actuator is at zero position at the highest tolerable working temperature of the electro-hydraulic actuatorTlThe difference value between the collected displacement and the displacement collected at normal temperature is in mm and T when the electro-hydraulic actuator is at the zero position at the lowest tolerable working temperature of the electro-hydraulic actuatorhThe maximum tolerance working temperature of the electro-hydraulic actuator is in the unit of DEG ClThe lowest tolerance working temperature of the electro-hydraulic actuator is set as the unit, and T is the temperature value of the electro-hydraulic actuator when the feedback displacement is collected in the step 3 and is set as the unitl≤T≤Th；
ΔLhWhen the actual displacement is the full-scale position of the electro-hydraulic actuator, the difference value between the displacement acquired at any temperature and the displacement acquired at normal temperature,
Figure BDA0001911423960000042
wherein HThThe difference value between the collected displacement and the displacement collected at normal temperature is in mm and H when the electro-hydraulic actuator is at the full-scale position at the highest tolerable working temperature of the electro-hydraulic actuatorTlThe difference value between the collected displacement and the displacement collected at normal temperature is in mm when the electro-hydraulic actuator is at the full-scale position at the lowest tolerance working temperature of the electro-hydraulic actuator;
Phthe displacement of the actuator actually collected at the full range position is measured in mm and P at normal temperaturelThe displacement actually collected by the actuator at the zero position is in mm at normal temperature.
Further, in step 7, the first PID control parameter Kp is 1.01, Ki0.006 and Kd0.001; the second PID control parameter K 'in the step 8'p＝1、K′i0.004 and K'd＝0。
Further, in the step 9, the control quantity is obtained by using an integral separation algorithm according to the first PID control parameter or the second PID control parameter.
Further, the actuating mechanism of the electro-hydraulic actuator is a gear pump and a piston output shaft in a hydraulic cylinder, when the control quantity is converted into the actuating quantity in the step 10, the rotating speed of the motor is greater than the minimum rotating speed of the motor, and the minimum rotating speed of the motor is as follows:
Figure BDA0001911423960000051
wherein n isminIs the minimum rotation speed of the motor in the unit of r/min, and S is the action area of the piston of the hydraulic cylinder in the unit of mm2Vmin is the minimum speed of the piston movement of the hydraulic cylinder, the unit is mm/s, m is the gear module of the gear pump, the unit is mm, Z is the number of teeth of the gear pump, ηNFor the efficiency of the gear pump at maximum load, B is the tooth width of the gear pump in mm.
Compared with the prior art, the invention has the following technical effects:
1. the displacement control method of the electro-hydraulic actuator adopts a segmented PID control method and an integral separation PID control method, so that the control efficiency of the control method is improved, and the control precision of the control method is improved;
2. the displacement control method of the electro-hydraulic actuator provided by the invention has the advantages that the temperature compensation method is provided for compensating the overall temperature drift of the electro-hydraulic actuator, the compensation of the feedback displacement collected by the displacement sensor is reflected in a centralized manner, and the control error caused by the temperature drift is eliminated;
3. the displacement control method of the electro-hydraulic actuator provided by the invention meets the control precision of the electro-hydraulic actuator under the multi-load working condition by limiting the minimum rotating speed of the motor;
4. the electro-hydraulic actuator displacement control method provided by the invention is verified by tests that the positioning accuracy of the system at normal temperature is less than +/-0.07% of the rated stroke and is superior to +/-0.15% indexes of foreign products; the linearity is less than +/-0.03% of the rated stroke and is better than +/-0.05% indexes of foreign products; the repetition precision is less than 0.02% of the rated travel and is superior to the index of 0.10% of foreign products.
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FIG. 1 is a flow chart of a displacement control method of an electro-hydraulic actuator provided by the invention;
FIG. 2 is a schematic diagram illustrating temperature compensation in a displacement control method for an electro-hydraulic actuator according to an embodiment of the present disclosure;
FIG. 3 is a positioning accuracy curve at normal temperature by using the displacement control method of the electro-hydraulic actuator provided by the present invention in an embodiment of the present invention;
FIG. 4 is a positioning accuracy curve at high and low temperatures by using the displacement control method of the electro-hydraulic actuator provided by the invention in one embodiment of the invention.
Detailed Description
The field control host computer: a processing device, generally a Programmable Logic Controller (PLC), for transmitting a control signal in a plant or an operation site controls various types of actuators to operate by outputting an analog quantity.
An electro-hydraulic actuator: the executing device for converting standard input signals (4-20mA, D.C.) into angular displacement output torque or linear displacement output force of 0-90 degrees corresponding to the input signals through electro-hydraulic conversion and hydraulic amplification comprises a communication system, a control system and an executing mechanism, wherein the communication system is used for communicating with a field control host and receiving control signals, the control system is used for operating a control method, and the executing mechanism is used for carrying out specific actions.
The control system comprises: any quantities of interest or variability within a machine, mechanism or other device can be maintained and varied in a desired manner by a control system, which is divided into open-loop control systems, which refer to systems controlled using closed-loop control methods, and closed-loop control systems, which include motors for driving actuators.
An executing mechanism: the invention is characterized in that the actuating mechanism is a piston and an output shaft in a hydraulic cylinder, the gear pump is a rotary pump which conveys liquid or supercharges the liquid by means of the change and movement of the working volume formed between a pump cylinder and a meshing gear, and the rotation of the gear pump is transmitted to the piston and the output shaft to generate linear movement.
The closed-loop control method comprises the following steps: closed-loop control refers to a control method in which a controlled output is returned to an input terminal as control in a certain manner, and is corrected based on feedback of the output of a controlled object, and is corrected by a fixed amount or a standard when a deviation between an actual controlled variable and a planned controlled variable is measured, and closed-loop control, which is generally negative feedback control, performs control based on a difference between the actual controlled variable and the planned controlled variable, such as a control faucet: firstly, an expected flow is provided for water flow in the mind, the existing flow is observed by eyes after the faucet is opened and compared with the expected value, and the current flow is continuously adjusted by hands to form a feedback closed-loop control.
The PID closed-loop control method comprises the following steps: PID is the abbreviation of Proportion (Proportion), Integral (Integral) and Differential (Differential coefficient), which respectively represent three control algorithms, and the parameters of the controller can be adjusted by an experimental method according to the qualitative relationship between the parameters of the controller and the dynamic performance and the steady-state performance of the system when the parameters (the proportional parameter Kp, the Integral parameter Ki and the Differential parameter Kd) of the PID controller are adjusted according to the output of the three parameter adjustment control methods of the PID controller.
Integral separation PID control method: when the deviation of the controlled quantity and the set value is large, the integral action is cancelled; when the controlled quantity is close to the given value, a PID closed-loop control method of integral control is introduced to eliminate the static error and improve the precision.
The temperature compensation method comprises the following steps: in some electronic products, some electronic components with positive and negative temperature coefficients are used, and taking resistance as an example, the positive temperature coefficient increases with temperature, the resistance value increases, and the negative temperature coefficient is just opposite. In application, for example, when a sensor is used, if an element with a temperature coefficient is used alone, the error is relatively large, and if the elements with positive and negative temperature coefficients are combined, positive and negative phases are balanced, and the error is relatively small.
The following are specific examples given by the inventors for further explanation of the technical solution of the present invention.
Example one
The embodiment discloses a displacement control method of an electro-hydraulic actuator, which is implemented after a control signal exceeds a certain variable quantity in a specific control mode of an electro-hydraulic actuator controller.
In this embodiment, as shown in fig. 1, a closed-loop control method for an electro-hydraulic actuator is provided, in which the electro-hydraulic actuator operates in a wide temperature range (-20 ℃ to +50 ℃), a wide load range (-45000N to +45000N), and a high-precision (0.15%) positioning requirement is to be met, so that the method is implemented by a PID closed-loop control algorithm, and since a PID algorithm needs to acquire a control signal and a feedback signal, the control method needs to operate after the electro-hydraulic actuator operates and can acquire the feedback signal.
The control method in the embodiment is operated in a control system of the electro-hydraulic actuator, and mainly operated on a microcontroller and a signal processing module.
The control method is executed according to the following steps:
step 1, initializing closed-loop control parameters, wherein the closed-loop control parameters comprise control precision; setting a response requirement parameter with the unit of mm;
the closed-loop control parameters also comprise closed-loop control output quantity, process variables and input and output modes;
in this embodiment, the control accuracy is set to be 0.03mm, the closed-loop control output and the process variable are both 0mm, the input is displacement, the output is motor speed and steering, and the response requirement parameter is 0.05 mm.
In this step, the control is performed when the difference between the control displacement and the feedback displacement satisfies the response requirement.
Step 2, judging whether a control cycle is reached currently, if so, executing step 3, otherwise, executing step 2, wherein the control cycle is a clock cycle of the signal processing module;
since the clock cycles of each microcontroller are different, i.e. step 2-step 11 are run once in each clock cycle of the microcontroller in this step.
In the present embodiment, the control period is 20 milliseconds.
Step 3, collecting a control signal and a feedback signal, wherein the control signal is a control displacement and the feedback signal is a feedback displacement;
in this step, utilize the control displacement volume that PLC sent out among the signal acquisition module collection communication system, utilize the feedback displacement volume of the actuating mechanism of signal acquisition module collection displacement sensor collection among the operating system.
When the electro-hydraulic actuator normally works and the environmental temperature changes in the range of minus 20 ℃ to plus 50 ℃, certain influence is generated on the system, so that the control precision of the electro-hydraulic actuator system is influenced, wherein the displacement sensor can generate temperature drift, the selected low-temperature coefficient linear displacement sensor is manufactured by adopting a non-contact magnetostrictive principle, the working range is 200mm, the temperature coefficient is 30ppm/K, and when the system normally works and the temperature changes in the range of minus 20 ℃ to plus 50 ℃, the measurement error delta L caused by the temperature drift of the sensor is as follows:
(Δ L) α × L × Δ T formula I
α -temperature coefficient, unit is ppm/K;
l is the sensor range, and the unit is mm;
Δ T-amount of temperature change in units of;
as shown in the formula I, the maximum error caused by the temperature drift of the sensor is 0.42mm, which has a great influence on the system precision.
Therefore, in order to improve the control precision of the electro-hydraulic actuator, when the feedback signal is acquired in the step 3, the feedback displacement is corrected by using a temperature compensation algorithm.
The existing temperature compensation method mainly modifies and compensates the temperature coefficient of the displacement sensor, but the method cannot be considered according to the overall situation of the electro-hydraulic actuator, because the electro-hydraulic actuator is in the working process, the influence of the temperature on the electro-hydraulic controller is not only reflected on the displacement sensor, but also reflected on the viscosity of oil, when the environmental temperature changes, the viscosity and the fluidity of the engine oil in the gear pump and the hydraulic cylinder are influenced, the higher the temperature is, the lower the viscosity of the engine oil is, the better the fluidity is, and vice versa. Therefore, when the system works, the moving speeds of piston rods in hydraulic cylinders with the same motor rotating speed at different temperatures are different, the requirement on the adaptability of a control algorithm is high, and the control precision can also generate certain influence, so that when the temperature drift of the electro-hydraulic actuator is compensated, comprehensive compensation is needed, and the displacement sensor is not only simply subjected to temperature compensation, so that when the temperature compensation method in the prior art is applied to the control method provided by the invention, the compensation result is inaccurate, and the control precision is reduced.
The temperature compensation method adopts a formula II to obtain the compensated feedback displacement P 'under the temperature value of the electro-hydraulic actuator and the temperature value of the electro-hydraulic actuator when the feedback displacement is acquired in the step 3 by adopting a displacement sensor'xIn mm:
Figure BDA0001911423960000111
wherein, PxThe displacement is actually acquired at the temperature of the electro-hydraulic actuator and is in mm;
ΔLlthe difference value between the displacement collected at any temperature and the displacement collected at normal temperature when the actual displacement is the zero position of the electro-hydraulic actuator,
Figure BDA0001911423960000112
wherein L isThThe difference value between the collected displacement and the collected displacement at normal temperature is measured in mm and L when the electro-hydraulic actuator is at zero position at the highest tolerable working temperature of the electro-hydraulic actuatorTlThe difference value between the collected displacement and the displacement collected at normal temperature is in mm and T when the electro-hydraulic actuator is at the zero position at the lowest tolerable working temperature of the electro-hydraulic actuatorhThe maximum tolerance working temperature of the electro-hydraulic actuator is in the unit of DEG ClThe lowest tolerance working temperature of the electro-hydraulic actuator is set as the unit, and T is the temperature value of the electro-hydraulic actuator when the feedback displacement is collected in the step 3 and is set as the unitl≤T≤Th；
ΔLhWhen the actual displacement is the full-scale position of the electro-hydraulic actuator, the difference value between the displacement acquired at any temperature and the displacement acquired at normal temperature,
Figure BDA0001911423960000121
wherein HThThe difference value between the collected displacement and the displacement collected at normal temperature is in mm and H when the electro-hydraulic actuator is at the full-scale position at the highest tolerable working temperature of the electro-hydraulic actuatorTlThe difference value between the collected displacement and the displacement collected at normal temperature is in mm when the electro-hydraulic actuator is at the full-scale position at the lowest tolerance working temperature of the electro-hydraulic actuator;
Phthe displacement of the actuator actually collected at the full range position is measured in mm and P at normal temperaturelThe displacement actually collected by the actuator at the zero position is in mm at normal temperature.
In this step, the normal temperature was 25 ℃.
In this example, the whole system was placed in a high and low temperature test chamber, the temperature of the test chamber was raised from room temperature to +50 ℃ at a span of 10 ℃ each time at the zero position of the system, and then lowered to-20 ℃ at the same span, and the zero position was recorded at each temperature point and compared with the room temperature position, and it was found that the offset was L when the temperature of the test chamber was-20 ℃TlThe position offset is L when the temperature of the test chamber is +50 DEG CTh(ii) a In the same way, the same test is carried out at the full range position of the system, and the position offset is respectively H at minus 20 ℃ and plus 50 DEG CTlAnd HThIn the zero position or the full scale, when the temperature changes within 5 ℃ to 35 ℃, the position offset is small, and the influence of the temperature drift on the system can be ignored, so that the system temperature compensation is only performed in the temperature range with large temperature influence, namely, in the embodiment, when the actuator is between-20 ℃ to 5 ℃ and 35 ℃ to 50 ℃, the displacement acquired by the displacement sensor needs to be compensated by adopting a temperature compensation method.
As shown in FIG. 2, the offset Δ L at any temperature at the zero position can be obtained according to the zero offset at high and low temperatures1Similarly, the offset Delta L of the system at the full scale position at any temperature can be obtainedh(ii) a Thereby converting an arbitrary position PXOffset amount Δ L ofXWhen the ambient temperature of the system changes, the measured value of the displacement sensor can be compensated according to formula III to obtain a compensated feedback displacement P 'of the system'X：
P′X＝PX+ΔLXFormula III
In the formula, PXThe feedback displacement collected by the sensor at any temperature.
In the embodiment, the maximum tolerable working temperature T of the electro-hydraulic actuatorh50 ℃ and the lowest tolerance working temperature T of the electro-hydraulic actuatorlThe maximum measuring range of the displacement sensor in the electro-hydraulic actuator is 500mm at the temperature of minus 20 ℃, and the zero position is 0 mm; the displacement P actually collected when the displacement sensor collects 500mm of displacement at 25 DEG Ch500mm, at 25 deg.C, displacement sensorDisplacement P actually acquired when 0m displacement is collectedlIs 0 mm.
And 3, calculating the displacement P 'acquired by the compensated displacement sensor when the displacement sensor acquires the feedback displacement in the step 3, wherein the temperature of the electro-hydraulic actuator is 40℃'xAt this time, the displacement P actually collected by the displacement sensorx＝160mm；
The displacement when the actual displacement is 0m at 50 deg.C is-12 mm, and the difference L between the actual displacement and the displacementThIs-12 mm; at the temperature of minus 20 ℃, when the actual displacement is 0mm, the displacement when the displacement sensor collects the actual displacement is 22mm, and the difference L between the actual displacement and the displacement isTl22mm, then:
Figure BDA0001911423960000131
the difference value H between the displacement quantity of 560mm and 500mm when the actual displacement is 500mm at 50 ℃ is acquired by the displacement sensorThIs 60 mm; the displacement is 480mm when the displacement sensor collects the actual displacement and the difference value H between the displacement and 500mm is acquired when the actual displacement is 500mm at the temperature of minus 20 DEG CTlIs-20 mm, then:
Figure BDA0001911423960000141
then it is determined that,
Figure BDA0001911423960000142
in this embodiment, with the displacement compensation method provided by the present invention, under the condition of 30 ℃, the displacement feedback amount actually acquired by the displacement sensor is 160mm, and the displacement feedback amount after actual compensation is 171 mm.
Step 4, calculating the absolute value of the difference between the feedback displacement and the control displacement, if the absolute value of the difference is greater than the response requirement parameter, executing step 5, otherwise, returning to step 2;
in this step, when the system is in a stopped state, and when the absolute value of the difference between the control displacement and the feedback displacement is smaller than the response requirement, which indicates that the control amount is too small, the electro-hydraulic actuator does not respond, for example, the response requirement is 0.01% of the full stroke, i.e., 0.05mm, when the control displacement is 0.5mm, the feedback displacement is 0.46mm, and the difference is 0.04mm, the electro-hydraulic actuator does not respond, and if the feedback displacement is 0.42mm, the difference is 0.08mm, and is larger than the response requirement, step 5 is performed to perform control adjustment.
Step 5, if the absolute value of the difference is less than or equal to the control precision, stopping the servo motor; if the absolute value of the difference is greater than the control precision, executing the step 6;
in this step, a stopping condition of the control method is set until when the absolute value of the difference between the feedback displacement and the control displacement meets the precision requirement, which indicates that the movement of the electro-hydraulic actuator has reached a required state, for example, the control displacement is 0.5mm, and the feedback displacement is 0.4999mm, so that the absolute value of the difference is 0.0001mm and the precision requirement is 0.001mm, in this case, the action of the actuator in the action system meets the requirement, so that no readjustment is needed, and at this time, the servo motor is stopped, so the action of the actuator is stopped; if the feedback displacement is 0.4800mm and the absolute value of the difference is 0.0200mm and the precision requirement is far from being met, step 6 is executed until the precision requirement is met, namely the servo motor is closed, namely the actuator is closed.
Step 6, if the absolute value of the difference is greater than the threshold, executing step 7, and if the absolute value of the difference is less than or equal to the threshold, executing step 8;
step 7, setting a first PID control parameter, wherein the first PID control parameter comprises Kp, Ki and Kd, and executing step 9;
step 8, setting a second PID control parameter, wherein the second PID control parameter comprises Kp ', Ki ' and Kd ', and executing step 9;
because the same group of PID parameters can not meet the precision requirements under all position differences at the same time under the full stroke of the system, and when the error is large, the system has longer adjustment time and is easy to generate large overshoot, two groups of PID control parameters are provided in the steps 6-8, the control method of the segmented PID is realized, when the absolute value of the difference value is large, the first PID control parameter is used for realizing the rapid reduction of the distance between the feedback displacement and the control displacement, but the overshoot phenomenon is easy to occur to the system under different working conditions; when the absolute value of the difference is small, the second PID control parameter is used for accurately adjusting the distance between the feedback displacement and the control displacement, but the speed is low, and the efficiency of the control method is improved by using the segmented PID control method.
Preferably, under a plurality of experiments of the inventor, the first PID control parameter Kp is determined to be 1.01 and Ki0.006 and Kd0.001; second PID control parameter K'p＝1、K′i0.004 and K'd＝0。
Step 9, obtaining a controlled variable by a PID control method according to the first PID control parameter or the second PID control parameter;
when the first PID control parameter or the second PID control parameter is obtained, the control quantity can be output by adopting the existing PID control algorithm, but the existing system has longer adjustment time because the integral effect is too strong and large overshoot is easy to generate, and in order to further improve the efficiency of the control method, the control quantity is obtained by utilizing an integral separation PID control method according to the first PID control parameter or the second PID control parameter in the step 8.
Step 10, converting the control quantity into an execution quantity;
in the step, the control method directly controls the rotating speed and the steering direction of the servo motor, but in the actual control process, the actuating mechanism of the electro-hydraulic actuator is a gear pump and a piston output shaft in a hydraulic cylinder, so that after the control quantity is converted into the rotating speed and the steering direction of the motor of the servo motor, the servo motor is used for driving the gear pump to rotate, the pressures of an upper cavity and a lower cavity in the hydraulic cylinder are changed, the piston and the output shaft are pushed to act, and the output shaft moves for a certain displacement.
Because when the ambient temperature changes, can influence the viscosity and the mobility of machine oil in gear pump and the pneumatic cylinder, the higher the temperature, the lower the machine oil viscosity mobility is better, otherwise opposite. Therefore, when the system works, the moving speeds of the piston rods in the hydraulic cylinders with the same motor rotating speed at different temperatures are different, the requirement on the adaptability of a control algorithm is high, and the control precision can also have certain influence.
In addition, in some cases, for example, when the actuator is under the conditions of no load and maximum or minimum load ± 45000N load respectively, the system works normally, when the target position is approached, the output motor rotation speed is the same according to the PID algorithm, and under different loads, the gear pump efficiency is different, so the actuator movement speed which can be realized by the same motor rotation speed is different, so that at a certain time of the system control period, the rotation speed is not enough to promote the actuator to move when the large load occurs, and the overshoot oscillation phenomenon occurs when the rotation speed is too large when the system is no load.
Optionally, when the control amount is converted into the execution amount in step 10, the rotation speed of the motor is greater than the minimum rotation speed of the motor, where the minimum rotation speed of the motor is:
Figure BDA0001911423960000171
wherein n isminIs the minimum rotation speed of the motor in the unit of r/min, and S is the action area of the piston of the hydraulic cylinder in the unit of mm2Vmin is the minimum speed of the piston movement of the hydraulic cylinder, the unit is mm/s, m is the gear module of the gear pump, the unit is mm, Z is the number of teeth of the gear pump, ηNEfficiency of the gear pump at maximum load.
The piston action areas of the two ends of the hydraulic cylinder in the system are the same, and the piston action area S can be obtained according to the diameters of the piston and the piston rod of the hydraulic cylinder, so that the flow speed relation of the hydraulic cylinder is shown as the formula V:
Q＝S×V×10-6x 60 formula V
In the formula: Q-Gear Pump flow, L/min;
v-hydraulic cylinder piston speed, mm/s;
s-piston area of action, mm2。
By the inherent characteristics of the gear pump, the relationship of the flow and the rotating speed of the gear pump is shown as formula VI:
Q＝2πdjmBnηv×10-6＝2πm2ZBnηv×10-6formula VI
In the formula: q-actual flow of gear pump, L/min;
djgear pitch diameter, mm;
m-gear module, mm;
b-tooth width, mm;
ηvgear pump efficiency (section clearance and radial clearance leakage);
z-number of teeth;
n-motor speed, r/min.
The relation between the motor rotating speed and the hydraulic cylinder piston running speed can be obtained as formula VII:
Figure BDA0001911423960000181
according to the test of the electro-hydraulic actuator, when the piston speed V of the hydraulic cylinder is very small, under the condition of a certain control period, the time for the electro-hydraulic actuator to reach the target position is longer, so the piston speed V of the hydraulic cylinder must be greater than Vmin(test: 0.4mm/s), the electro-hydraulic actuator can quickly reach the target position when approaching, and the positioning precision is met.
The gear pump test shows that the gear pump efficiency is different when the system is unloaded and loaded, and the unloaded efficiency is greater than the loaded efficiency, namely η0＞ηNThe lower the efficiency when the load is larger; therefore, according to formula VII, when the piston has a minimum velocity VminFor fixed value, the motor speed N under different loads is different, and in order to satisfy the normal operation of the system under the maximum load of 45000N, in this embodiment, the minimum motor speed is as shown in formula IV, wherein ηNGear pump efficiency at a load of 45000N.
The whole system needs to meet the positioning precision requirement under all working conditions, so the minimum rotating speed of the motor must be nminThe rotation speed can cause the piston of the hydraulic cylinder to move when the system is in no-loadThe speed of the line is fast, and overshoot oscillation is possible to occur, and the problem can be solved by shortening the control period, so that the system meets all working condition requirements.
And 11, controlling the action of the executing mechanism according to the executing quantity, and returning to the step 2 until the electro-hydraulic actuator meets the requirement of controlling precision and is closed.
In this step, after the control method outputs the rotation speed and the steering of the motor, the execution mechanism is controlled to act to complete one adjustment.
Example two
In this embodiment, the precision test is performed on the displacement control method of the electro-hydraulic actuator provided by the invention, and the test includes a normal temperature test and a high and low temperature test.
The method provided by the invention is combined with the existing electro-hydraulic actuator, and the normal temperature test process comprises the following steps:
the first step is as follows: powering on the equipment and setting output; electrifying the electro-hydraulic actuator, and setting control parameters including control precision of 0.03mm by operating a keyboard;
the second step is that: setting the minimum rotating speed of the motor and the maximum high speed of the motor (the maximum rotating speed cannot exceed the rated rotating speed); setting parameters such as system position and signals;
the third step: simulating DCS with a standard signal source to set a target position, responding the signal by a controller, adjusting an actuator to reach a corresponding position, and recording the position;
the fourth step: the signal source settings were tested starting at 4mA, increasing up to 20mA at 2mA intervals, and decreasing down to 4mA at 2mA intervals under different loads.
According to the test steps, the positioning precision test is carried out under different load working conditions (no load, 20000N, 45000N, -2000N, -45000N), and the test result is shown in figure 3.
And (4) conclusion: when the load is changed from-45000N to 45000N, the positioning accuracy of the system is less than +/-0.07% of the rated stroke at normal temperature.
High and low temperature tests: the system is placed into a high-low temperature test chamber to perform a positioning precision test under a high-low temperature environment, the steps are the same as the steps of the test under normal temperature, and the test result is shown in fig. 4.
And (4) conclusion: the system has no-load state, and the positioning accuracy of the system is less than +/-0.15% of the rated stroke under the environment of-20 ℃ and 50 ℃.

Claims (4)

1. The displacement control method of the electro-hydraulic actuator is characterized by being used for controlling the execution quantity of the electro-hydraulic actuator according to a control signal of a field control host, wherein the execution quantity comprises the rotating speed and the steering direction of a servo motor in the electro-hydraulic actuator, and the control method is implemented according to the following steps:
step 1, initializing closed-loop control parameters, wherein the closed-loop control parameters comprise control precision and have the unit of mm; setting a response requirement parameter with the unit of mm;
step 2, judging whether a control cycle is reached currently, if so, executing step 3, otherwise, executing step 2, wherein the control cycle is a clock cycle of an electro-hydraulic actuator control system, and the unit is ms;
step 3, collecting a control signal and a feedback signal, wherein the control signal is a control displacement sent by a field control host, and the feedback signal is a feedback displacement of an actuating mechanism in the electro-hydraulic actuator;
step 4, calculating the absolute value of the difference between the feedback displacement and the control displacement, if the absolute value of the difference is greater than the response requirement parameter, executing step 5, otherwise, returning to step 2;
step 5, if the absolute value of the difference is less than or equal to the control precision, stopping the servo motor; if the absolute value of the difference is greater than the control precision, executing the step 6;
step 6, if the absolute value of the difference is greater than the threshold, executing step 7, and if the absolute value of the difference is less than or equal to the threshold, executing step 8;
step 7, setting a first PID control parameter, wherein the first PID control parameter comprises Kp, Ki and Kd, and executing step 9;
step 8, setting a second PID control parameter, wherein the second PID control parameter comprises Kp ', Ki ' and Kd ', and executing step 9;
step 9, obtaining a control quantity by using a PID control method according to the first PID control parameter or the second PID control parameter, wherein the control quantity is the displacement of an actuating mechanism in the electro-hydraulic actuator;
step 10, converting the control quantity into an execution quantity;
step 11, controlling the action of an actuating mechanism of the electro-hydraulic actuator according to the actuating quantity, and returning to the step 2;
when a feedback signal is collected, correcting the feedback displacement by using a temperature compensation method;
the temperature compensation method adopts a formula II to obtain the compensated feedback displacement P 'under the temperature value of the electro-hydraulic actuator when the feedback displacement is collected in the step 3'xThe unit is mm, wherein adopt displacement sensor to gather the feedback displacement volume:
Figure FDA0002325913550000021
wherein, PxThe displacement is actually acquired at the temperature of the electro-hydraulic actuator and is in mm;
ΔLlthe difference value between the displacement collected at any temperature and the displacement collected at normal temperature when the actual displacement is the zero position of the electro-hydraulic actuator,
Figure FDA0002325913550000022
wherein L isThThe difference value between the collected displacement and the collected displacement at normal temperature is measured in mm and L when the electro-hydraulic actuator is at zero position at the highest tolerable working temperature of the electro-hydraulic actuatorTlThe difference value between the collected displacement and the displacement collected at normal temperature is in mm and T when the electro-hydraulic actuator is at the zero position at the lowest tolerable working temperature of the electro-hydraulic actuatorhThe maximum tolerance working temperature of the electro-hydraulic actuator is in the unit of DEG ClThe lowest tolerance working temperature of the electro-hydraulic actuator is set as the unit, and T is the position of the electro-hydraulic actuator when the feedback displacement is collected in the step 3Temperature value in deg.C, Tl≤T≤Th；
ΔLhWhen the actual displacement is the full-scale position of the electro-hydraulic actuator, the difference value between the displacement acquired at any temperature and the displacement acquired at normal temperature,
Figure FDA0002325913550000031
wherein HThThe difference value between the collected displacement and the displacement collected at normal temperature is in mm and H when the electro-hydraulic actuator is at the full-scale position at the highest tolerable working temperature of the electro-hydraulic actuatorTlThe difference value between the collected displacement and the displacement collected at normal temperature is in mm when the electro-hydraulic actuator is at the full-scale position at the lowest tolerance working temperature of the electro-hydraulic actuator;
Phthe displacement of the actuator actually collected at the full range position is measured in mm and P at normal temperaturelThe displacement actually collected by the actuator at the zero position is in mm at normal temperature.
2. The displacement control method for the electro-hydraulic actuator according to claim 1, wherein in the step 7, the first PID control parameter Kp is 1.01, Ki0.006 and Kd0.001; the second PID control parameter K 'in the step 8'p＝1、K′i0.004 and K'd＝0。
3. The displacement control method of the electro-hydraulic actuator according to claim 2, wherein in step 9, the control quantity is obtained by using an integral separation algorithm according to the first PID control parameter or the second PID control parameter.
4. The displacement control method of the electro-hydraulic actuator according to claim 1, wherein the actuator of the electro-hydraulic actuator is a gear pump and a piston output shaft in a hydraulic cylinder, and when the control quantity is converted into the execution quantity in step 10, the rotation speed of a servo motor in the electro-hydraulic actuator is greater than the minimum rotation speed of the motor, and the minimum rotation speed of the motor is as follows:
Figure FDA0002325913550000041
wherein n isminIs the minimum rotation speed of the motor in the unit of r/min, and S is the action area of the piston of the hydraulic cylinder in the unit of mm2Vmin is the minimum speed of the piston movement of the hydraulic cylinder, the unit is mm/s, m is the gear module of the gear pump, the unit is mm, Z is the number of teeth of the gear pump, ηNFor the efficiency of the gear pump at maximum load, B is the tooth width of the gear pump in mm.
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Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1923559A1 (en) * 2006-11-14 2008-05-21 Delphi Technologies, Inc. A method of controlling a piezoelectric actuator
CN201444035U (en) * 2008-12-19 2010-04-28 上海诺玛液压系统有限公司 Displacement transducer used for electro-hydraulic servo valve
CN102562714A (en) * 2011-12-27 2012-07-11 同济大学 Compound control method of speed and position of hydraulic cylinder system based on displacement feedback
CN104407639A (en) * 2014-11-26 2015-03-11 中国工程物理研究院总体工程研究所 Servo control method and servo control device for high-frequency hydraulic shock excitation system
CN105159081A (en) * 2015-09-02 2015-12-16 中国民航大学 Intelligent control method of steering engine electro-hydraulic loading system
CN105697470A (en) * 2016-01-18 2016-06-22 西安电子科技大学 Hydraulic movement control system and method for cantilever truss fatigue test
CN107703887A (en) * 2017-11-11 2018-02-16 成都海逸机电设备有限公司 A kind of Digit Control Machine Tool Electro-hydraulic Loading Servo System and control method
CN108181803A (en) * 2018-01-02 2018-06-19 海南大学 The fuzzy self-adaption Fractional Order PID method for adjusting rotation speed and system of Turbo-generator Set
CN108873702A (en) * 2018-07-17 2018-11-23 太原科技大学 A kind of linear active disturbance rejection control method and device of electro-hydraulic position servo control system

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1923559A1 (en) * 2006-11-14 2008-05-21 Delphi Technologies, Inc. A method of controlling a piezoelectric actuator
DE602006009683D1 (en) * 2006-11-14 2009-11-19 Delphi Tech Inc Method for controlling a piezoelectric actuator
CN201444035U (en) * 2008-12-19 2010-04-28 上海诺玛液压系统有限公司 Displacement transducer used for electro-hydraulic servo valve
CN102562714A (en) * 2011-12-27 2012-07-11 同济大学 Compound control method of speed and position of hydraulic cylinder system based on displacement feedback
CN104407639A (en) * 2014-11-26 2015-03-11 中国工程物理研究院总体工程研究所 Servo control method and servo control device for high-frequency hydraulic shock excitation system
CN105159081A (en) * 2015-09-02 2015-12-16 中国民航大学 Intelligent control method of steering engine electro-hydraulic loading system
CN105697470A (en) * 2016-01-18 2016-06-22 西安电子科技大学 Hydraulic movement control system and method for cantilever truss fatigue test
CN107703887A (en) * 2017-11-11 2018-02-16 成都海逸机电设备有限公司 A kind of Digit Control Machine Tool Electro-hydraulic Loading Servo System and control method
CN108181803A (en) * 2018-01-02 2018-06-19 海南大学 The fuzzy self-adaption Fractional Order PID method for adjusting rotation speed and system of Turbo-generator Set
CN108873702A (en) * 2018-07-17 2018-11-23 太原科技大学 A kind of linear active disturbance rejection control method and device of electro-hydraulic position servo control system

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