A multi-cylinder synchronous proportional valve nonlinear compensation system and a compensation method

Abstract

The application discloses a kind of multi-cylinder synchronous proportional valve nonlinear compensation system and compensation method, the system includes man-machine interaction unit, motion controller, analog output module, man-machine interaction unit is connected with motion controller, motion controller is connected with multiple proportional direction valves by analog output module, proportional direction valve is connected with hydraulic cylinder respectively, the piston rod extension end of hydraulic cylinder is connected with mechanical load, simultaneously, hydraulic cylinder is also connected with cylinder displacement sensor, cylinder displacement sensor is connected with motion controller by detection module;The method includes data recording and storage, dotting, nonlinear compensation curve determination and storage, nonlinear compensation curve calling, hydraulic cylinder synchronous operation;The application measures the actual curve of proportional direction valve and cylinder running speed by dotting method, and the difference between theoretical curve and actual measurement curve is loaded into the control command of proportional direction valve, to ensure the high-precision synchronous operation of multiple hydraulic cylinders.

Description

Technical Field

[0001] This invention relates to the field of hydraulic equipment control technology, specifically to a nonlinear compensation system and method for a multi-cylinder synchronous proportional valve. Background Technology

[0002] With the development of aerospace technology, modern machining, and oil and gas pipeline industries, electro-hydraulic proportional synchronous control technology has been widely applied in various metal sheet forming and processing fields. In particular, multi-cylinder synchronous positioning control has become the mainstream solution in the industry. In multi-cylinder synchronous positioning control systems, due to the influence of many factors such as frictional resistance, machining and installation, the response and performance of hydraulic components, and cylinder off-center loading, there is a large nonlinear region between the command given by the electro-hydraulic proportional directional valve and the speed of the actuator. This region is the key factor affecting the synchronous operation and positioning accuracy of each cylinder. If linear control theory is used to control the synchronous positioning of multiple hydraulic cylinders, the difference in the closed-loop feedback of the cylinder position will cause frequent adjustments to the proportional directional valve command, resulting in vibration of the hydraulic actuator, large positioning errors, and poor system stability.

[0003] To ensure the stable operation of high-precision synchronous positioning of multiple hydraulic cylinders, it is essential to accurately measure the nonlinear region of the proportional directional valve and compensate and correct the command input in this region. This ensures that the hydraulic cylinder operating speed remains consistent under different command input values, which is the fundamental method for achieving stable operation of the high-precision synchronous positioning system of multiple hydraulic cylinders. Summary of the Invention

[0004] The purpose of this invention is to address the technical defects in electro-hydraulic proportional multi-cylinder synchronous control systems, where the operating speeds of hydraulic cylinders driven by proportional valves of the same model vary under the same command setting due to differences in the nonlinear regions of the proportional valves. This results in poor positioning accuracy of the mechanical load driven by multiple cylinders and unstable system operation. The invention provides an automatic measurement and compensation method for the nonlinear curve of the proportional valve in multi-cylinder synchronous positioning control, which effectively improves the positioning accuracy and stability of the multi-cylinder synchronous control system.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A nonlinear compensation system for a multi-cylinder synchronous proportional valve includes a human-machine interface unit, a motion controller, and an analog output module. The human-machine interface unit is connected to the motion controller via a control circuit. The motion controller is connected to multiple proportional directional valves via the analog output module. The proportional directional valves are connected to hydraulic cylinders respectively. The piston rod extension end of the hydraulic cylinder is connected to a mechanical load. At the same time, a cylinder displacement sensor is also connected to the hydraulic cylinder. The cylinder displacement sensor is connected to the motion controller via a detection module.

[0007] A nonlinear compensation method for a multi-cylinder synchronous proportional valve, the method employing the aforementioned nonlinear compensation system for a multi-cylinder synchronous proportional valve, includes the following steps:

[0008] Step 1: Data Recording and Storage: First, the operating speed of the hydraulic cylinders is set as a percentage of the theoretically calculated value. All hydraulic cylinders are then synchronously started by the motion controller. The actual displacement values ​​of each hydraulic cylinder are fed back to the motion controller by the cylinder displacement sensor through the position detection module. The motion controller processes the detected displacement to calculate the corresponding operating speed and records the resulting operating speed and the corresponding proportional directional valve command value in the motion controller's data storage area. A set of corresponding data is recorded every set scan cycle until the hydraulic cylinder operation is complete. In this way, a large amount of data on the actual speed and commands of the hydraulic cylinder during operation is recorded in the motion controller's data storage area.

[0009] Step 2, Plotting Points: Set the hydraulic cylinder running speed value recorded in Step 1 as the X-axis of the rectangular coordinate system and the command value of the proportional directional valve as the Y-axis. Use the plotting point method to obtain the trajectory curve of the proportional directional valve command and the hydraulic cylinder running speed during actual operation.

[0010] Step 3: Measurement and storage of nonlinear compensation curves: Change the set value of the hydraulic cylinder's running speed, and repeatedly measure the trajectory curves of the proportional directional valve command and the hydraulic cylinder's running speed when the hydraulic cylinder is actually running at different speed ranges, according to the method in the steps. Compare all the measured curves with the theoretically calculated curves to obtain the nonlinear compensation curves of the proportional directional valve at different speed ranges. After editing the curve through the human-machine interaction unit, save it to the compensation curve storage area of ​​the motion controller.

[0011] Step 4: Calling up the nonlinear compensation curve: In practical applications, the motion controller automatically calls up the corresponding compensation curve of the proportional directional valve according to the set operating speed of the hydraulic cylinder, and applies the curve to the analog output module to control the opening size of the proportional direction, so as to accurately control the operating speed and displacement of the hydraulic cylinder.

[0012] Step 5: Synchronous Operation of Hydraulic Cylinders: Using the same method, measure the trajectory curves of the commands of all proportional directional valves and the corresponding operating speeds of the hydraulic cylinders. Obtain the nonlinear compensation curve of the proportional directional valves and apply it to the analog output module. This ensures that the hydraulic cylinders maintain the same operating speed under the same set speed. At this time, since the control command magnitude of the proportional directional valve corresponding to each hydraulic cylinder is determined by both the theoretical calculation value and the nonlinear compensation value, the voltage command output by the analog output module will also differ. This difference is caused by the nonlinear compensation curve obtained from the measurement in order to achieve synchronous operation of the hydraulic cylinders.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] (1) In the process of multi-cylinder driving mechanical load operation, the trajectory curves of each proportional directional valve command and the cylinder running speed are measured by plotting points. The functional relationship between the proportional directional valve command and the cylinder running speed in different intervals is obtained from the curves, and the obtained functional relationship is preset into the control command. The operation of the cylinder is determined by the actual measured functional relationship to determine the magnitude of the proportional directional valve command. In this way, the control command magnitude of the corresponding proportional valve for different hydraulic cylinders at the same running speed can be determined. The motion controller outputs the control command to the proportional directional valve corresponding to each cylinder through the analog module, which effectively solves the nonlinear control of the proportional valve in multi-cylinder synchronous positioning control and ensures the accuracy and stability of multi-cylinder synchronous positioning.

[0015] (2) The technical solution of the present invention is applicable to all application scenarios in which two or more sets of hydraulic cylinders 5 drive mechanical loads 6 together. It can effectively solve the synchronization of hydraulic cylinders 5 when multiple cylinders are synchronously positioned, and ensure the positioning accuracy of mechanical loads 6 and the stability of the whole system.

[0016] (3) The technical solution of the present invention accurately measures the actual curve of the running speed of the proportional directional valve and the cylinder by plotting points, and loads the difference between the theoretical curve and the actual measured curve (i.e. the compensation curve of the nonlinear region of the proportional directional valve) into the control command of the proportional directional valve, thereby completely eliminating the difference in the actual speed and displacement of the hydraulic cylinder under the same command caused by external factors, and ensuring high-precision synchronous operation of multiple hydraulic cylinders. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the composition structure of the present invention;

[0018] Figure 2 This is a block diagram illustrating the control principle of the present invention;

[0019] In the diagram: 1-Human-machine interaction unit; 2-Motion controller; 3-Analog output module; 4-Proportional directional valve; 5-Hydraulic cylinder; 6-Mechanical load; 7-Cylinder displacement sensor; 8-Position detection module. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to specific embodiments.

[0021] like Figure 1As shown, a nonlinear compensation system for a multi-cylinder synchronous proportional valve includes a human-machine interface unit 1, a motion controller 2, and an analog output module 3. The human-machine interface unit 1 is connected to the motion controller 2 via a control circuit. The motion controller 2 is connected to multiple proportional directional valves 4 via the analog output module 3. The proportional directional valves 4 are respectively connected to hydraulic cylinders 5. The piston rod extension end of the hydraulic cylinder 5 is connected to a mechanical load 6. At the same time, a cylinder displacement sensor 7 is also connected to the hydraulic cylinder 5. The cylinder displacement sensor 7 is connected to the motion controller 2 via a detection module 8.

[0022] The multi-cylinder synchronous proportional valve nonlinear compensation system provided by this invention is a miniature independent control system that can be integrated into any multi-cylinder synchronous control system. It mainly includes a motion controller, an analog output module, a proportional directional valve, hydraulic cylinders, cylinder displacement sensors, and a position detection module. The motion controller outputs ±10V voltage commands as a percentage to the proportional directional valve via the analog module. The magnitude of the proportional directional valve command controls the cylinder's operating speed. The cylinder displacement and speed are fed back to the motion controller via cylinder displacement sensors connected to the position detection module, forming a fully closed-loop control system. Theoretically, as long as the hydraulic cylinders are set to the same operating speed, the proportional directional valve will respond with the same control command, ensuring synchronized operation of the cylinders' positions and speeds while simultaneously issuing start or stop commands. However, in practical applications, even under the same command, the operating speed and displacement of each cylinder differ, leading to adverse factors such as mechanical load skew, vibration, and poor positioning accuracy in multi-cylinder driven systems.

[0023] like Figure 2 As shown, a nonlinear compensation method for a multi-cylinder synchronous proportional valve, employing the aforementioned multi-cylinder synchronous proportional valve nonlinear compensation system, includes the following steps:

[0024] Step 1: Data Recording and Storage: First, the operating speed of hydraulic cylinder 5 is set as a percentage of the theoretically calculated value. All hydraulic cylinders 5 are then synchronously started by motion controller 2. The actual displacement value of each hydraulic cylinder 5 is fed back to motion controller 2 by cylinder displacement sensor 7 via position detection module 8. Motion controller 2 processes the detected displacement of hydraulic cylinder 5 internally to calculate the corresponding operating speed, and records the resulting operating speed and the corresponding command value of proportional directional valve 4 in the data storage area of ​​motion controller 2. A set of corresponding data is recorded every set scan cycle until hydraulic cylinder 5 completes its operation. In this way, a large amount of data on the actual speed and command of hydraulic cylinder 5 during operation is recorded in the data storage area of ​​motion controller 2.

[0025] Step 2, Plotting: Set the running speed value of hydraulic cylinder 5 in the data recorded in Step 1 as the X-axis of the rectangular coordinate system, and set the command value of proportional directional valve 4 as the Y-axis. By plotting, obtain the trajectory curve of the command of proportional directional valve 4 and the running speed of hydraulic cylinder 5 during actual operation.

[0026] Step 3: Measurement and storage of nonlinear compensation curve: Change the set value of the running speed of hydraulic cylinder 5, and repeatedly measure the trajectory curve of the command of proportional directional valve 4 and the running speed of hydraulic cylinder 5 when hydraulic cylinder 5 is running at different speed ranges according to the method in step 1. Compare all the measured curves with the theoretical calculation curves to obtain the nonlinear compensation curves of proportional directional valve 4 at different speed ranges. After editing the curve through human-machine interaction unit 1, save it to the compensation curve storage area of ​​motion controller 2.

[0027] Step 4: Calling up the nonlinear compensation curve: In practical applications, the motion controller 2 automatically calls up the corresponding compensation curve of the proportional directional valve 4 according to the set operating speed of the hydraulic cylinder 5, and applies the curve to the analog output module 3 to control the opening size of the proportional directional valve 4, so as to accurately control the operating speed and displacement of the hydraulic cylinder 5.

[0028] Step 5: Synchronous Operation of Hydraulic Cylinders: Using the same method, measure the trajectory curves of the commands of all proportional directional valves 4 and the corresponding operating speeds of hydraulic cylinders 5. Obtain the nonlinear compensation curve of the proportional directional valves 4 and apply it to the analog output module 3. This ensures that the hydraulic cylinders 5 maintain the same operating speed under the same set speed. At this time, since the control command magnitude of the proportional directional valves 4 corresponding to each hydraulic cylinder 5 is determined by both the theoretical calculation value and the nonlinear compensation value, the voltage command output by the analog output module 3 will also be different. This difference is caused by the nonlinear compensation curve obtained from the measurement in order to achieve the synchronous operation of the hydraulic cylinders 5.

[0029] The technical solution of the present invention is applicable to all application scenarios in which two or more sets of hydraulic cylinders 5 drive mechanical loads 6 together. It can effectively solve the synchronization problem of hydraulic cylinders 5 when multiple cylinders are operating in synchronous positioning mode, and ensure the positioning accuracy of mechanical loads 6 and the stability of the entire system.

[0030] The technical solution of this invention accurately measures the actual speed curves of the proportional directional valve and the hydraulic cylinder using the point-plotting method, and loads the difference between the theoretical curve and the actual measured curve (i.e., the compensation curve for the nonlinear region of the proportional directional valve) into the control command of the proportional directional valve, thereby completely eliminating the difference in the actual speed and displacement of the hydraulic cylinder under the same command caused by external factors, and ensuring high-precision synchronous operation of multiple hydraulic cylinders.

[0031] The above are merely preferred embodiments of the present invention. It should be noted that, for those skilled in the art, based on the technical teachings provided by the present invention and as common knowledge in the field of mechanical manufacturing, other equivalent modifications and improvements can be made, and these should also be considered within the scope of protection of the present invention.

Claims

1. A nonlinear compensation method for a multi-cylinder synchronous proportional valve, characterized in that, A multi-cylinder synchronous proportional valve nonlinear compensation system is adopted. The compensation system includes a human-machine interaction unit (1), a motion controller (2), and an analog output module (3). The human-machine interaction unit (1) and the motion controller (2) are connected through control lines. The motion controller (2) is connected to multiple proportional directional valves (4) through the analog output module (3). The proportional directional valves (4) are connected to hydraulic cylinders (5) respectively. The piston rod extension end of the hydraulic cylinder (5) is connected to a mechanical load (6). At the same time, a cylinder displacement sensor (7) is also connected to the hydraulic cylinder (5). The cylinder displacement sensor (7) is connected to the motion controller (2) through a position detection module (8). The method includes the following steps: Step 1, Data Recording and Storage: First, set the running speed of the hydraulic cylinder (5) as a percentage of the theoretical calculation value. Then, start all the hydraulic cylinders (5) synchronously through the motion controller (2). Feed back the actual displacement value of each hydraulic cylinder (5) to the motion controller (2) through the position detection module (8) via the cylinder displacement sensor (7). The motion controller (2) calculates the corresponding running speed by processing the detected displacement of the hydraulic cylinder (5) through internal data processing. Record the obtained running speed and the command value of the corresponding proportional directional valve (4) in the data storage area of ​​the motion controller (2). Record a set of corresponding data every set scanning cycle until the hydraulic cylinder (5) finishes running. In this way, a large amount of data of the actual speed and command of the hydraulic cylinder (5) during operation is recorded in the data storage area of ​​the motion controller (2). Step 2, plotting points: Set the running speed value of the hydraulic cylinder (5) in the data recorded in Step 1 as the X-axis of the rectangular coordinate system, and set the command value of the proportional directional valve (4) as the Y-axis. By plotting points, the trajectory curve of the command of the proportional directional valve (4) and the running speed of the hydraulic cylinder (5) during actual operation is obtained. Step 3, Nonlinear Compensation Curve Measurement and Storage: Change the set value of the running speed of the hydraulic cylinder (5), and repeatedly measure the trajectory curve of the command of the proportional directional valve (4) and the running speed of the hydraulic cylinder (5) when the hydraulic cylinder (5) is running in different speed ranges according to the method in Step 1. Compare all the measured curves with the theoretical calculation curves to obtain the nonlinear compensation curves of the proportional directional valve (4) in different speed ranges. After editing the curve through the human-machine interaction unit (1), save it to the compensation curve storage area of ​​the motion controller (2). Step 4: Calling the nonlinear compensation curve: In practical applications, the motion controller (2) automatically calls the corresponding compensation curve of the proportional directional valve (4) according to the set running speed of the hydraulic cylinder (5), and applies the curve to the analog output module (3) to control the opening size of the proportional directional valve (4) to achieve the purpose of accurately controlling the running speed and displacement of the hydraulic cylinder (5). Step 5: Synchronous operation of hydraulic cylinders: Using the methods in Step 3 and Step 4, measure the trajectory curves of the commands of all proportional directional valves (4) and the running speed of the corresponding hydraulic cylinders (5), obtain the nonlinear compensation curve of the proportional directional valves (4) and apply it to the analog output module (3), and ensure that the hydraulic cylinders (5) have the same running speed under the same set speed.

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