Multi-hydraulic-cylinder cross-coupling synchronization control system and synchronization control method

Abstract

The application provides a multi-hydraulic-cylinder coupling and synchronous control system, comprising a plurality of hydraulic position servo links, each of which is used for controlling the action of a heave hydraulic cylinder; wherein, each two of the hydraulic position servo links are coupled to realize the synchronous control of each two of the hydraulic position servo links. The multi-hydraulic-cylinder coupling and synchronous control system provided by the application guarantees the synchronous control of two heave hydraulic cylinders by setting a plurality of hydraulic position servo links and coupling each two of the hydraulic position servo links, overcomes the phase lag, improves the stability of the hydraulic control system, and guarantees the synchronous control precision of the multi-hydraulic-cylinder.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydraulic synchronous control, in particular to a multi-hydraulic-cylinder coupled synchronous control system and a multi-hydraulic-cylinder coupled synchronous control method. BACKGROUND

[0002] Compared with other forms of synchronous control systems such as motor synchronous control systems, the hydraulic synchronous control system has the advantages of convenient operation, easy control, simple structure and being very suitable for high-power application occasions. Therefore, in more and more metal processing equipment, metallurgical machinery, engineering machinery and driving devices, in order to increase the driving force, double hydraulic cylinders or even multiple hydraulic cylinders are usually used to work together, and the urgent need for high-precision synchronous control technology arises at the historic moment.

[0003] Hydraulic synchronous control has always been widely concerned by the industry, but high-precision synchronous control has not been truly solved. The main influencing factors are: the dead zone of the proportional valve, the time-varying flow gain, the friction of the hydraulic cylinder, the manufacturing precision of the hydraulic system, etc. In addition to the above factors, when multiple hydraulic cylinders drive a load at the same time, the unbalance of the load, the leakage of the hydraulic cylinder, the coupling effect between multiple hydraulic cylinders and other factors make the proportional valve controlled hydraulic cylinder synchronous system a typical nonlinear and time-varying control system. Especially for large load carrying platform objects, the synchronous system is prone to the following problems: first, the system load inertia is large, which is easy to cause phase lag; second, the hydraulic system has large elasticity and small damping, which is easy to cause oscillation; third, the heave, roll and pitch motions are weakly coupled and there is mechanical deformation. In view of the existence of these key problems, especially how to obtain high quality and stable robustness of the system at high speed and high precision, the current control method has not fundamentally solved the synchronization control problem of multiple sets of valve controlled hydraulic cylinders. SUMMARY

[0004] The present application provides a multi-hydraulic-cylinder coupled synchronous control system and a multi-hydraulic-cylinder coupled synchronous control method to solve the problem of low synchronization control precision of multiple sets of valve controlled hydraulic cylinders in the prior art.

[0005] The present application provides a multi-hydraulic-cylinder coupled synchronous control system, comprising: a plurality of hydraulic position servo links, each of which is used to control the action of a heave hydraulic cylinder; wherein each two hydraulic position servo links are coupled to realize synchronous control of each two hydraulic position servo links.

[0006] According to the application, a multi-hydraulic-cylinder coupled synchronization control system is provided, and the plurality of hydraulic position servo links comprises four hydraulic position servo links, wherein the first hydraulic position servo link is cross-coupled with the third hydraulic position servo link, and the second hydraulic position servo link is cross-coupled with the fourth hydraulic position servo link.

[0007] According to the application, a multi-hydraulic-cylinder coupled synchronization control system is provided, and each hydraulic position servo link comprises a heave hydraulic cylinder, a servo valve electrically connected with the heave hydraulic cylinder and used for driving the heave hydraulic cylinder to act, and a position composite control mechanism electrically connected with the servo valve and used for acquiring an opening degree instruction of a valve core of the servo valve and driving the valve core of the servo valve to act.

[0008] According to the application, a multi-hydraulic-cylinder coupled synchronization control system is provided, and the position composite control mechanism comprises a position controller assembly used for position closed-loop processing calculation of the heave hydraulic cylinder, a speed controller used for speed closed-loop processing calculation of the heave hydraulic cylinder, and a differential pressure controller assembly electrically connected with the servo valve and used for differential pressure closed-loop control of the heave hydraulic cylinder.

[0009] According to the application, a multi-hydraulic-cylinder coupled synchronization control system is provided, and the position controller assembly comprises a position controller comprising a first PID adjustment sub-module and used for calculating a speed control amount of the heave hydraulic cylinder according to a PID control algorithm, and a position sensor installed on a piston rod of the heave hydraulic cylinder and used for detecting a stroke of an extension and retraction position of the piston rod of the heave hydraulic cylinder.

[0010] According to the application, a multi-hydraulic-cylinder coupled synchronization control system is provided, and the speed controller comprises a proportional feedforward adjustment sub-module and used for calculating a differential pressure control amount of the heave hydraulic cylinder.

[0011] According to the application, a multi-hydraulic-cylinder coupled synchronization control system is provided, and the differential pressure controller assembly comprises a differential pressure controller comprising a second PID adjustment sub-module and used for calculating a valve core control amount of the servo valve, and a differential pressure sensor installed on oil supply pipes of a rod cavity and a rodless cavity of the heave hydraulic cylinder and used for detecting pressures of the rod cavity and the rodless cavity of the heave hydraulic cylinder and a difference value of the pressures.

[0012] According to the application, a multi-hydraulic-cylinder coupled synchronization control system is provided, and further comprises a position cross-coupling controller used for pressure compensation of the differential pressure sensor.

[0013] The application provides a method for performing multiple hydraulic cylinder coupling and synchronization control by using the multiple hydraulic cylinder coupling and synchronization control system, comprising: detecting the stroke of the piston rod extension and retraction position of the heave hydraulic cylinder of each hydraulic position servo link; detecting the pressure of the rod cavity and the rodless cavity of the heave hydraulic cylinder of each hydraulic position servo link and the difference value thereof; performing pressure difference compensation on the pressure difference sensor of each hydraulic position servo link according to the detected stroke of the piston rod extension and retraction position; and driving the heave hydraulic cylinder to act by a servo valve.

[0014] According to the application, a multiple hydraulic cylinder coupling and synchronization control method is provided, further comprising: performing position closed loop processing calculation, speed closed loop processing calculation and pressure difference closed loop control of the heave hydraulic cylinder.

[0015] The multiple hydraulic cylinder coupling and synchronization control system provided by the application guarantees the synchronization control of two heave hydraulic cylinders, overcomes phase lag, improves the stability of the hydraulic control system and guarantees the synchronization control precision of multiple hydraulic cylinders by arranging multiple hydraulic position servo links and coupling each two of them. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0017] Figure 1 FIG. 1 is a schematic diagram of the multiple hydraulic cylinder coupling and synchronization control system provided by the application;

[0018] Figure 2 FIG. 2 is a flow chart of the multiple hydraulic cylinder coupling and synchronization control method provided by the application.

[0019] Reference signs:

[0020] 1: position controller; 2: speed controller; 3: pressure difference controller;

[0021] 4: servo valve; 5: heave hydraulic cylinder; 6: pressure difference sensor;

[0022] 7: position sensor; 8: position cross-coupling controller; 9: load platform. DETAILED DESCRIPTION

[0023] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be clearly and completely described below in conjunction with the accompanying drawings in the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0024] The present application will be described below in conjunction with Figure 1 and Figure 2 The present application provides a multi-hydraulic-cylinder coupled synchronous control system and a multi-hydraulic-cylinder coupled synchronous control method.

[0025] In an embodiment of the present application, the multi-hydraulic-cylinder coupled synchronous control system comprises a plurality of hydraulic position servo links, each of which is used to control the action of one heave hydraulic cylinder 5. Among them, every two hydraulic position servo links are coupled to realize the synchronous control of every two hydraulic position servo links, and each hydraulic position servo link is connected with the load platform 9.

[0026] Specifically, the number of the plurality of hydraulic position servo links can be an even number greater than or equal to 4, wherein every two hydraulic position servo links are coupled. Generally, two hydraulic position servo links with large characteristic difference and synchronous control deviation are coupled to obtain good coupling effect and ensure the good synchronization of the two coupled hydraulic position servo links. In the coupling process, if it is found that the effect of the two coupled hydraulic position servo links is not good, the two coupled hydraulic position servo links can be adjusted to be coupled with other hydraulic position servo links to ensure the synchronization of every two hydraulic position servo links in controlling the heave hydraulic cylinder 5, so that the phase lag can be overcome and the synchronization control precision of the multi-hydraulic-cylinder can be ensured when the load inertia of the load platform 9 is large.

[0027] The multi-hydraulic-cylinder coupled synchronous control system provided by the embodiment of the present application ensures the synchronous control of the two heave hydraulic cylinders by setting a plurality of hydraulic position servo links and coupling every two hydraulic position servo links, overcomes the phase lag, improves the stability of the hydraulic control system, and ensures the synchronization control precision of the multi-hydraulic-cylinder.

[0028] As shown in Figure 1 In an embodiment of the present application, the plurality of hydraulic position servo links comprises four hydraulic position servo links, wherein the first hydraulic position servo link and the third hydraulic position servo link are cross-coupled, and the second hydraulic position servo link and the fourth hydraulic position servo link are cross-coupled.

[0029] Specifically, in practical work, coupling can be performed according to the characteristics of the hydraulic position servo links that are specifically set. Two hydraulic position servo links with large differences in characteristics and synchronous control deviations can be coupled together to ensure the synchronization of the control of the swaying hydraulic cylinder 5.

[0030] like Figure 1 As shown, in one embodiment of the present invention, each hydraulic position servo link includes: a position composite control mechanism, a servo valve 4, and a swaying hydraulic cylinder 5. Specifically, the position composite control mechanism obtains the desired position value of the swaying hydraulic cylinder 5 from the upper-level control device or upper-level control module, and performs position closed-loop processing calculation, speed closed-loop processing calculation, and differential pressure closed-loop control to obtain the opening command of the servo valve 4 spool. After D / A conversion, it outputs an electrical signal to drive the servo valve 4 spool to move. The servo valve 4 is electrically connected to the swaying hydraulic cylinder 5, thereby realizing the drive control of the swaying hydraulic cylinder 5.

[0031] Furthermore, such as Figure 1 As shown, in one embodiment of the present invention, the position composite control mechanism includes: a position controller assembly, a speed controller 2, and a differential pressure controller assembly.

[0032] Specifically, the position controller assembly is used to perform closed-loop position processing calculations for the helical hydraulic cylinders 5. Further, the position controller assembly includes a position controller 1 and a position sensor 7. The position controller includes a first PID control submodule, which is used to calculate the speed control quantity of each helical hydraulic cylinder 5 based on the position deviation of the helical hydraulic cylinders 5 using a PID control algorithm. The position sensor 7 is mounted on the piston rod of each helical hydraulic cylinder 5 to detect the stroke of the piston rod at its extension / retraction position.

[0033] Furthermore, in one embodiment of the present invention, optionally, the number of each position sensor 7 is one.

[0034] The speed controller 2 includes a proportional feedforward adjustment submodule. This proportional feedforward adjustment submodule uses a proportional and feedforward control algorithm to calculate the differential pressure control of each helical hydraulic cylinder 5 based on the speed control of each helical hydraulic cylinder 5, so as to overcome phase lag and prevent oscillation of the hydraulic system.

[0035] The differential pressure controller assembly includes a differential pressure controller 3 and a differential pressure sensor 6. The differential pressure controller 3 includes a second PID control submodule, which uses a PID control algorithm to calculate the control quantity of the valve core of each servo valve 4 based on the differential pressure control of each oscillating hydraulic cylinder 5. The differential pressure sensor 6 includes oil supply pipes respectively installed on the rod chamber and rodless chamber of each oscillating hydraulic cylinder 5, used to detect the pressure and its difference between the rod chamber and rodless chamber of the oscillating hydraulic cylinder 5.

[0036] Further, in one embodiment of the present application, the number of differential pressure sensors 6 is 2.

[0037] As shown in the figure, in one embodiment of the present application, the multi-cylinder coupled synchronous control system further comprises a position cross-coupling controller 8 for pressure compensation of the differential pressure controller 3 of each heave cylinder 5 according to the extension and retraction position information fed back by the piston rod of each heave cylinder 5. Figure 1

[0038] Specifically, the position controller 1 subtracts the position feedback value from the position expected value to obtain the position deviation, and adopts the PID control algorithm to obtain the speed expected value, i.e.

[0039]

[0040] wherein U(i) is the output, T is the sampling time interval, Kp is the integral coefficient, Ti is the integral time constant, Td is the differential time constant, and e(i) is the deviation between the position expected value and the position detection value of each heave cylinder 5. The speed controller 2 obtains the speed deviation based on the speed expected value and the differential speed value, adopts the proportional and feedforward compensation control algorithm for speed closed-loop processing, and obtains the differential pressure expected value (torque expected value); the differential pressure controller 3 performs differential pressure closed-loop processing based on the torque expected value and the differential pressure feedback value, and obtains the servo valve 4 spool opening command, which is converted by D / A and then output as an electric signal to drive the servo valve 4 spool to act, thereby realizing the driving control of the heave cylinder 5. The position sensor 7 obtains the extension and retraction position measurement value of the heave cylinder 5, which is used for the position closed-loop control of the outer ring position controller 1.

[0041] The intermediate ring speed controller 2 is composed of a proportional controller and a feedforward controller, and on the basis of proportional control, the speed feedforward control is added. Compared with feedback control, the speed feedforward control needs to take the difference of the position variable to calculate the speed, and the actual position and the predicted speed value of the target position are obtained, and the speed value is updated before each input to the speed feedback controller, so that the latest data is used in the loop cycle.

[0042] The differential pressure sensor 6 is installed on the oil supply pipe of the rod cavity and the rodless cavity of each heave cylinder 5, and is used to obtain the pressure measurement value and the differential pressure measurement value of the heave cylinder 5, and is used for the closed-loop control of the driving torque of the heave cylinder 5 by the inner ring differential pressure controller 3.

[0043] The differential pressure sensor 6 adopts the PID control algorithm to calculate the servo valve 4 spool opening value, i.e.

[0044]

[0045] ​Wherein, U(i) is the output, T is the sampling time interval, Kp is the integral coefficient, Ti is the integral time constant, Td is the differential time constant, and e(i) is the deviation between the pressure difference detection value and the expected value of each heave hydraulic cylinder chamber. The inner loop pressure difference controller 3 performs pressure difference closed loop control according to the pressure difference compensation value obtained by the position cross-coupling controller 8 and the spool opening value from the pressure difference controller 3.

[0046] The embodiment of the present application also provides a multi-hydraulic-cylinder coupled synchronous control method, and the specific steps include:

[0047] Step 01: detecting the stroke of the piston rod extension and retraction position of the heave hydraulic cylinder 5 of each hydraulic position servo link;

[0048] Step 02: detecting the pressure and the difference value of the rod chamber and the rodless chamber of the heave hydraulic cylinder 5 of each hydraulic position servo link;

[0049] Step 03: performing pressure difference compensation on the pressure difference sensor 6 of each hydraulic position servo link according to the detected stroke of the piston rod extension and retraction position;

[0050] Step 04: driving the heave hydraulic cylinder 5 to act by the servo valve 4.

[0051] Specifically, the position sensor 7 detects the stroke of the piston rod extension and retraction position of each heave hydraulic cylinder 5, the position controller 1 adopts a PID control algorithm to calculate the speed control quantity of each heave hydraulic cylinder 5 according to the position deviation of the heave hydraulic cylinder 5, the speed controller 2 adopts a proportional and feedforward control algorithm to calculate the pressure difference control quantity of each heave hydraulic cylinder 5 according to the speed control quantity of each heave hydraulic cylinder 5, the pressure difference controller 3 adopts a PID control algorithm to calculate the control quantity of the spool of each servo valve 4 according to the pressure difference control of each heave hydraulic cylinder 5, the pressure difference sensor 6 detects the pressure and the difference value of the rod chamber and the rodless chamber of the heave hydraulic cylinder 5, and the position cross-coupling controller 8 performs pressure compensation on the pressure difference controller 3 of each heave hydraulic cylinder 5 according to the piston rod feedback extension and retraction position information of each heave hydraulic cylinder 5.

[0052] In an embodiment of the present application, the multi-hydraulic-cylinder coupled synchronous control method further includes: performing position closed loop processing calculation, speed closed loop processing calculation and pressure difference closed loop control of the heave hydraulic cylinder 5.

[0053] Specifically, the position controller 1 subtracts the position feedback value from the position expected value to obtain the position deviation, and adopts a PID control algorithm to obtain the speed expected value, that is:

[0054]

[0055] Wherein, U(i) is the output, T is the sampling time interval, Kp is the integral coefficient, Ti is the integral time constant, Td is the differential time constant, e(i) is the deviation of each heave hydraulic cylinder 5 position expected value and position detection value. The speed controller 2 is based on the above speed expected value and the differential speed value, the speed deviation is calculated, and the proportional, feedforward compensation control algorithm is used for speed closed loop processing, and the pressure difference expected value (torque expected value) is calculated; the pressure difference controller 3 is based on the above torque expected value and the pressure difference feedback value, and the pressure difference closed loop processing is carried out, and the each servo valve 4 valve core opening degree instruction is calculated, and after D / A conversion, the electric signal is output to drive the servo valve 4 valve core to act, thereby realizing the driving control of the heave hydraulic cylinder 5. Wherein, the position sensor 7 obtains the heave hydraulic cylinder 5 extension position measurement value, which is used for the position closed loop control of the outer ring position controller 1.

[0056] The intermediate ring speed controller 2 is composed of a proportional controller and a feedforward controller, and on the basis of proportional control, the speed feedforward control is increased. Compared with feedback control, the speed feedforward control needs to calculate the difference of the position variable to calculate the speed, and the actual position and the predicted speed value of the target position are obtained. The speed value is updated before each input to the speed feedback controller, so that the latest data is used in the loop cycle.

[0057] The pressure difference sensor 6 is installed on the oil supply pipe of each heave hydraulic cylinder 5 rod cavity and rodless cavity, which is used to obtain the pressure measurement value and the pressure difference measurement value of the two cavities of the heave hydraulic cylinder 5, and is used for the closed loop control of the driving torque of the heave hydraulic cylinder 5 by the inner ring pressure difference controller 3.

[0058] The above pressure difference sensor 6 uses the PID control algorithm to calculate the servo valve 4 valve core opening degree value, that is:

[0059]

[0060] Wherein, U(i) is the output, T is the sampling time interval, Kp is the integral coefficient, Ti is the integral time constant, Td is the differential time constant, e(i) is the deviation of each heave hydraulic cylinder two cavity pressure expected value and pressure difference detection value. The inner ring pressure difference controller 3 carries out pressure difference closed loop control according to the pressure difference compensation value calculated by the position cross coupling controller 8 and the valve core opening degree value from the pressure difference controller 3.

[0061] Finally, it should be pointed out that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for coupled synchronous control of multiple hydraulic cylinders, characterized in that, The method of multi-hydraulic cylinder coupling and synchronization control is based on a multi-hydraulic cylinder coupling and synchronization control system, which includes multiple hydraulic position servo links, each of which controls the movement of a helical hydraulic cylinder; wherein, every two hydraulic position servo links are cross-coupled to achieve synchronous control of every two hydraulic position servo links. Each of the hydraulic position servo links includes: a heave hydraulic cylinder; a servo valve electrically connected to the heave hydraulic cylinder for driving the heave hydraulic cylinder to move; and a position composite control mechanism electrically connected to the servo valve for acquiring the opening command of the servo valve spool and driving the servo valve spool to move. The position composite control mechanism includes: a position controller assembly for performing position closed-loop processing calculations for the helical hydraulic cylinder; a speed controller for performing speed closed-loop processing calculations for the helical hydraulic cylinder; and a differential pressure controller assembly electrically connected to the servo valve for performing differential pressure closed-loop control of the helical hydraulic cylinder. The position controller assembly includes: a position controller, including a first PID adjustment submodule, for calculating the speed control quantity of the swaying hydraulic cylinder according to a PID control algorithm; and a position sensor, installed on the piston rod of the swaying hydraulic cylinder, for detecting the stroke of the piston rod at the extension and retraction position of the swaying hydraulic cylinder. The speed controller includes a proportional feedforward adjustment submodule, which uses a proportional and feedforward control algorithm to calculate the differential pressure control of each helical hydraulic cylinder based on the speed control of each helical hydraulic cylinder, in order to overcome phase lag. The differential pressure controller assembly includes: a differential pressure controller, including a second PID adjustment submodule, which uses a PID control algorithm to calculate the control quantity of each servo valve core based on the differential pressure control of each helical hydraulic cylinder; and a differential pressure sensor, installed on the oil supply pipes of the rod chamber and rodless chamber of the helical hydraulic cylinder, for detecting the pressure and the difference between the rod chamber and rodless chamber of the helical hydraulic cylinder. A position cross-coupling controller is used to compensate the differential pressure sensor of each helical hydraulic cylinder based on the extension and retraction position information fed back by the piston rod of each helical hydraulic cylinder. The method for multi-hydraulic cylinder coupling and synchronous control includes: The stroke of the piston rod extension / retraction position of the heave hydraulic cylinder of each of the hydraulic position servo links is detected; Detect the pressure and the difference between the rod-side and rodless-side chambers of the swaying hydraulic cylinder of each hydraulic position servo link; Differential pressure compensation is performed on the differential pressure sensor of each hydraulic position servo link based on the detected stroke of the piston rod extension / retraction position; The servo valve drives the oscillating hydraulic cylinder to move; The position closed-loop processing calculation, speed closed-loop processing calculation, and differential pressure closed-loop control of the helical hydraulic cylinder are performed.

2. The method for multi-hydraulic cylinder coupling and synchronous control according to claim 1, characterized in that, The plurality of hydraulic position servo links include four hydraulic position servo links, wherein the first hydraulic position servo link is cross-coupled with the third hydraulic position servo link, and the second hydraulic position servo link is cross-coupled with the fourth hydraulic position servo link.

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