Precise pressure control method for hydraulic system

Abstract

The invention relates to a precise pressure control method for a hydraulic system, which comprises the following steps of: setting a theoretical value Ui of hydraulic pressure, and simultaneously collecting an actual value Uo of the hydraulic pressure; calculating an error value between the theoretical value Ui and the actual value Uo of each group so as to obtain an array eform [1. N]; iteration is carried out on the array eform [1. N]; solving an average value of the array eform [1. N] to obtain an average value array mform [1. N]; comparing the data in the array eform [1. N] and the data in the average value array mform [1. N] to obtain a jitter array shake [1. N]; a band array range [1. N] is set, range [1] is a mean value stable band, and range [2] is a jitter allowed band; determining that the mean value is stable when the average value [i] is within the range [1], and obtaining the mean value of the mean value array; on the premise of stability, when more than two pieces of data are not in the range of the jitter allowable band (2), jitter is judged; and on the premise of jitter, trying to jitter PID parameters in sequence, and after data enter a jitter allowable band, carrying out delay judgment for 2 seconds and jitter removal judgment, so that accurate control on hydraulic pressure can be realized through the method.

Description

Technical Field

[0001] The present invention relates to the field of hydraulic technology, and in particular to a method for accurately controlling the pressure of a hydraulic system. Background Art

[0002] In the chemical gunpowder production industry, it is necessary to conduct rigorous testing on the performance and parameters of gunpowder, so as to adjust the gunpowder formula and finally obtain the evaluation results based on the test data. In order to avoid casualties, automated testing equipment is currently used to replace manual testing. The automated testing equipment uses hydraulics as the power source and is fully automated in the assembly of gunpowder tooling and data collection. Specific test process: loading gunpowder--> screwing two threaded gunpowder barrels together (collecting data)--> ignition test after meeting the standards. The accuracy of hydraulic pressure directly affects the test results. At present, due to the lack of precise control of hydraulic pressure, the test is often interrupted.

[0003] The prior art discloses: CN114483246B discloses a method for controlling the oil pressure of a fully variable oil pump, comprising the following steps: S10, judging whether the engine is in a starting condition through a camshaft position sensor signal, if so, controlling the oil pump to build up oil pressure; if not, not starting the oil pump; wherein the oil pressure building in S10 is to control the oil pump to quickly build up oil pressure using an open-loop maximum displacement; S20, when it is detected that the oil pressure is built up under the engine starting condition, entering the oil pressure stepless adjustment control judgment to judge whether there is an abnormal enabling condition Occurs, if not, enter step S30; wherein, the abnormal enabling condition in S20 refers to a VVT stuck fault or an oil pressure sensor fault or a battery voltage below a certain value fault; if an abnormal enabling condition occurs, when a VVT stuck fault or an oil pressure sensor fault or a battery voltage below a certain value fault is detected, the fully variable oil pump oil pressure adopts a fixed duty cycle signal open-loop control, and specific duty cycle values ​​are set separately in different fault modes. When two or more faults occur at the same time, the maximum duty cycle is taken for output; S30, when the engine controller When the oil pressure stepless adjustment control is detected and no abnormal enabling conditions occur, the oil pump pressure enters the closed-loop dynamic control mode, and the engine controller calculates the target oil pressure through the engine speed and engine load signal, and gives the expected duty cycle value to control the oil pump, and feeds back the actual oil pressure; S40, the oil pressure sensor converts the measured AD voltage signal into the actual oil pressure, and calculates the average value of M times, and inputs it into the engine controller for comparison with the target oil pressure, and performs PID control according to the difference between the actual oil pressure average value and the target oil pressure. Adjust and output the duty cycle signal after PID adjustment; S50, perform battery voltage compensation correction on the duty cycle signal after PID adjustment, and compare it with the duty cycle limit, and finally output the duty cycle signal to accurately control the oil pressure; the S50 includes: comparing the duty cycle signal after battery voltage compensation correction with the duty cycle limit, when the duty cycle signal is greater than the duty cycle limit and the duration is greater than the set time n seconds, the duty cycle limit is output, otherwise, the duty cycle signal after battery voltage correction is output, so as to realize dynamic closed-loop control of the oil pressure of the fully variable oil pump.

[0004] Although the prior art discloses an oil pressure control method, it mainly reduces the loss by controlling the oil pressure. Summary of the invention

[0005] The technical problem solved by the present invention is to overcome the problems existing in the prior art and provide a method for accurately controlling the pressure of a hydraulic system to achieve stable testing by accurately controlling the hydraulic pressure.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A method for accurately controlling pressure of a hydraulic system is disclosed, the method comprising the following steps:

[0008] S1: Set the theoretical value of hydraulic pressure Ui and collect the actual value of hydraulic pressure Uo;

[0009] S2: Calculate the error value between each set of theoretical value Ui and actual value Uo, thereby obtaining the array e_form[1..N]; and iterate the array e_form[1..N];

[0010] S3: Get the average value array m_form[1..N] of the array e_form[1..N];

[0011] S4: Compare the data in the array e_form[1..N] and the average value array m_form[1..N] to obtain the shake array shake[1..N];

[0012] S5: Set the band array range[1..N], where range[1] is the mean stable band and range[2] is the jitter allowable band;

[0013] S6: When m_form[i] is within the range[1], the mean is determined to be stable, and the mean of the mean array is obtained; under the premise of stability, if more than 2 data are not within the jitter allowable band range[2], it is determined to be jittery; under the premise of jitter, try the jitter PID parameters in turn. After the data enters the jitter allowable band, a 2s delay is made to determine and clear the jitter judgment.

[0014] Preferably, in step S2, in the array e_form[1..N], the data with the smaller subscripts are the latest collected data.

[0015] Preferably, in S2, the most recently calculated error value replaces e_form[1] in the array e_form[1..N], and other data are shifted back in sequence according to the subscript numbering to complete data iteration.

[0016] Preferably, in step S4, a jitter array shake[1..N] is obtained by subtraction.

[0017] Preferably, range[1] and range[2] are both constants, and range[3..N] are backup values.

[0018] Preferably, N is 10.

[0019] Preferably, in step S6, the jitter is determined by the data processor 1.

[0020] Preferably, in step S6, if after all jitter PID parameters have been tried and the jitter determination still cannot be exited, the test is terminated and an alarm is triggered to restart.

[0021] Preferably, the method further comprises using the data processor 2 to judge the sudden change of the tightening angle.

[0022] Preferably, the method for judging the sudden change of the tightening angle is as follows: take the value of e_form[1] and the value of e_form[2] in the array e_form[1..N], and calculate the difference between the two values; add the differential parameter Kd to obtain the gradient value; when the gradient value is greater than 3 times the jitter allowable band, it is determined that the tightening angle has undergone an instantaneous sudden change; when a sudden change occurs, the value of the integral link ei is directly and completely cleared, otherwise the integral continues to be superimposed.

[0023] Compared with the prior art, the present invention has the following effects:

[0024] 1. Hydraulic system pressure precision control method The hydraulic value is collected and processed, and the data is jittered and jittered. Finally, the actual value of the hydraulic pressure is guaranteed to be within a reasonable range, thereby ensuring the normal test of the test equipment.

[0025] 2. By judging the sudden change of tightening angle, avoid instantaneous pressure shock and no-load. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a flow chart of a method for precise pressure control of a hydraulic system according to the present invention;

[0027] Figure 2 A control principle diagram of a hydraulic system pressure precision control method according to the present invention;

[0028] Figure 3 The invention discloses a method for accurately controlling pressure of a hydraulic system, in which the tightening angle changes suddenly.

[0029] Figure 4 This is a rendering of a hydraulic system pressure precision control method of the present invention. DETAILED DESCRIPTION

[0030] In order to clearly illustrate the technical features of the present solution, the present invention is described in detail below through specific implementation methods and in conjunction with the accompanying drawings.

[0031] In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present application is not limited to the specific embodiments disclosed below.

[0032] In addition, in the description of the present application, it should be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0033] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0034] In the present application, unless otherwise clearly specified and limited, a first feature "above" or "below" a second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments or examples.

[0035] Example 1

[0036] like Figures 1-2 As shown, a method for accurately controlling the pressure of a hydraulic system is disclosed, comprising the following steps:

[0037] S1: Set the theoretical value of hydraulic pressure Ui and collect the actual value of hydraulic pressure Uo;

[0038] S2: Calculate the error value between each set of theoretical value Ui and actual value Uo, thereby obtaining the array e_form[1..N]; and iterate the array e_form[1..N];

[0039] S3: Get the average value array m_form[1..N] of the array e_form[1..N];

[0040] S4: Compare the data in the array e_form[1..N] and the average value array m_form[1..N] to obtain the shake array shake[1..N];

[0041] S5: Set the band array range[1..N], where range[1] is the mean stable band and range[2] is the jitter allowable band;

[0042] S6: When m_form[i] is within the range[1], the mean is determined to be stable, and the mean of the mean array is obtained; under the premise of stability, if more than 2 data are not within the jitter allowable band range[2], it is determined to be jittery; under the premise of jitter, try the jitter PID parameters in turn. After the data enters the jitter allowable band, a 2s delay is made to determine and clear the jitter judgment.

[0043] In this embodiment, the hydraulic theoretical value Ui is set for the power source of the test setting, and the actual hydraulic output value Uo is measured by the sensor. The theoretical value Ui is greater than the actual value Uo. Multiple theoretical values ​​Ui are set in sequence, so that multiple actual values ​​Uo are obtained accordingly. The errors between multiple groups of theoretical values ​​Ui and actual values ​​Uo are compared to obtain the hydraulic deviation array e_form[1..N]. The subscript 1 in the hydraulic error array e_form[1..N] represents the deviation data of the first group, and N represents the deviation data of the Nth group. The theoretical value Ui is continuously input, so that the value of the deviation array e_form[1..N] is iteratively updated in time.

[0044] Calculate the sum of the deviation array e_form[1..N] and divide it by N to get the average value of the deviation array e_form[1..N]. Since the deviation array is always updated iteratively, each time the deviation array e_form[1..N] updates a data, the average value of a different deviation value array can be calculated. In this way, the average value array m_form[1..N] of the deviation array e_form[1..N] is obtained.

[0045] Compare the data in the deviation array e_form[1..N] and the average value array m_form[1..N] to obtain the jitter array shake[1..N].

[0046] The average value array m_form[1..N] is judged. When m_form[i] is within the range[1], the average value is determined to be stable, and the average value of the average value array is obtained. Under the premise of stability, if more than two data are not within the jitter allowable band range[2], it is determined to be jitter. When jitter occurs, the jitter PID parameters are used to delay the judgment for 2 seconds after the data enters the jitter allowable band, thereby eliminating the jitter.

[0047] By collecting the actual value of the hydraulic pressure and comparing the actual value with the theoretical value, the jitter array is finally obtained. The jitter array is judged to eliminate the jitter. Finally, the test equipment can be tested normally.

[0048] Kp proportional controller: According to the real-time difference e_form[1] value, adjust the opening size of the proportional valve and the speed of the variable frequency motor to make the pressure change effect reach Kp times of e_form[1]. It is continuously updated over time. It is updated approximately every 5ms.

[0049] Kd*s differential controller: According to the change rate of e_form[1] (i.e., whether it changes fast or slow), adjust the opening size of the proportional valve and the speed of the variable frequency motor so that the pressure change effect reaches Kd times the derivative of e_form[1]. It is continuously iterated and updated over time, and the values ​​of each iteration are accumulated. It is updated approximately every 5ms.

[0050] Ki / s ​​integral controller: According to the real-time value of e_form[1], adjust the opening size of the proportional valve and the speed of the variable frequency motor to make the pressure change effect reach Ki times of e_form[1]. It is continuously updated over time. It is updated once every 5ms. That is, it is updated 200 times in 1 second.

[0051] By setting appropriate Kp, Kd, ​​Ki values ​​and adjusting the overall integral value of the integral controller, precise control of the hydraulic pressure can be achieved. The adjustment process is the real-time iterative update of the above three controllers to control the opening size of the proportional valve and the speed of the variable frequency motor.

[0052] Example 2

[0053] A method for accurately controlling pressure of a hydraulic system is disclosed, comprising the following steps:

[0054] S1: Set the theoretical value of hydraulic pressure Ui and collect the actual value of hydraulic pressure Uo;

[0055] S2: Calculate the error value between each set of theoretical value Ui and actual value Uo, thereby obtaining the array e_form[1..N]; and iterate the array e_form[1..N];

[0056] S3: Get the average value array m_form[1..N] of the array e_form[1..N];

[0057] S4: Compare the data in the array e_form[1..N] and the average value array m_form[1..N] to obtain the shake array shake[1..N];

[0058] S5: Set the band array range[1..N], where range[1] is the mean stable band and range[2] is the jitter allowable band;

[0059] S6: When m_form[i] is within the range[1], the mean is determined to be stable, and the mean of the mean array is obtained; under the premise of stability, if more than 2 data are not within the jitter allowable band range[2], it is determined to be jittery; under the premise of jitter, try the jitter PID parameters in turn. After the data enters the jitter allowable band, a 2s delay is made to determine and clear the jitter judgment.

[0060] The difference between this embodiment and the first embodiment is that in step S2, in the array e_form[1..N], the data with a smaller subscript is the latest collected data.

[0061] The most recently calculated error value replaces e_form[1] in the array e_form[1..N], and the other data are shifted back in sequence according to the subscript number to complete the data iteration.

[0062] The shake array shake[1..N] is obtained by subtracting the values ​​of the average value array m_form[1..N] from the values ​​of the array e_form[1..N].

[0063] In the band array range[1..N], range[1] is the mean stable band, and range[2] is the jitter allowable band. The mean stable band and jitter allowable band are common sense and are set based on experience. Other values ​​are backup values.

[0064] In order to further improve the precise control of hydraulic pressure, each array includes ten values, that is, N is 10. By increasing the values ​​included in each array, the accuracy of the data is improved and the error is reduced.

[0065] The jitter determination can be performed automatically by the data processor 1, without manual determination, thereby reducing human error. When all jitter PID parameter attempts are completed and the jitter determination still cannot be exited, the test is terminated and an alarm is issued to restart.

[0066] Example 3

[0067] like Figure 3 As shown, a method for accurately controlling the pressure of a hydraulic system is disclosed, comprising the following steps:

[0068] S1: Set the theoretical value of hydraulic pressure Ui and collect the actual value of hydraulic pressure Uo;

[0069] S2: Calculate the error value between each set of theoretical value Ui and actual value Uo, thereby obtaining the array e_form[1..N]; and iterate the array e_form[1..N];

[0070] S3: Get the average value array m_form[1..N] of the array e_form[1..N];

[0071] S4: Compare the data in the array e_form[1..N] and the average value array m_form[1..N] to obtain the shake array shake[1..N];

[0072] S5: Set the band array range[1..N], where range[1] is the mean stable band and range[2] is the jitter allowable band;

[0073] S6: When m_form[i] is within the range[1], the mean is determined to be stable, and the mean of the mean array is obtained; under the premise of stability, if more than 2 data are not within the jitter allowable band range[2], it is determined to be jittery; under the premise of jitter, try the jitter PID parameters in turn. After the data enters the jitter allowable band, a 2s delay is made to determine and clear the jitter judgment.

[0074] In the automatic tightening part of the gunpowder tooling, there are strict technical requirements for hydraulic pressure to ensure that the torque value meets the standard and the torque data cannot exceed the standard. In the actual tightening process of the thread, the relationship between the change in torque and the rotation angle is neither smooth nor linear, and is extremely uncertain. During the tightening process, the pressure gradually increases, and there will be a sudden change in the tightening angle, resulting in a huge tightening torque. This uncertainty is prone to instantaneous pressure shock and no-load conditions.

[0075] The difference between this embodiment and the above embodiment is that: the value of e_form[1] and the value of e_form[2] in the deviation array e_form[1..N] are taken, and the difference between the two values ​​is calculated; the differential parameter Kd is added to the difference to obtain the gradient value. The gradient value is judged, specifically, when the gradient value is greater than 3 times the jitter allowable band, it is determined that the tightening angle has undergone an instantaneous mutation; when the mutation occurs, the value of the integral link ei is directly and completely cleared, otherwise the integral continues to be superimposed.

[0076] Through the above method, the instantaneous change of the tightening angle can be avoided, thereby avoiding instantaneous pressure shock and no-load.

[0077] like Figure 4 ,The actual effect diagram after applying this technology, the two arrows are the abnormal conditions generated at the moment of tightening the thread, and it can be seen that no overshoot occurs after the abnormality. From the timeline, both rapidity and overshoot are taken into account. The output value has a quick response when it suddenly changes, but the algorithm is quickly adjusted to avoid overshoot.

[0078] Parameters: Kp[0] is 1.3, Kd[0] is 0.1, Ki[0] is 2.5.

[0079] Obviously, the above embodiments are merely examples for clearly illustrating the technical solutions of the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all implementation methods here. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for precise pressure control of a hydraulic system, characterized in that: The method comprises the following steps: S1: Set the theoretical value of hydraulic pressure Ui and collect the actual value of hydraulic pressure Uo; S2: Calculate the error value between each set of theoretical value Ui and actual value Uo, thereby obtaining the array e_form[1..N]; and iterate the array e_form[1..N]; S3: Calculate the average value of the array e_form[1..N] to obtain the average value array m_form[1..N]; S4: Compare the data in the array e_form[1..N] and the average value array m_form[1..N] to obtain the shake array shake[1..N]; S5: Set the band array range[1..N], where range[1] is the mean stable band and range[2] is the jitter allowable band; S6: When m_form[i] is within the range[1], the mean is determined to be stable, and the mean of the mean array is obtained; under the premise of stability, if more than 2 data are not within the jitter allowable band range[2], it is determined to be jittery; under the premise of jitter, try the jitter PID parameters in turn. After the data enters the jitter allowable band, a 2s delay is made to determine and clear the jitter judgment.

2. A hydraulic system pressure precision control method according to claim 1, characterized in that: In step S2, in the array e_form[1..N], the data with smaller subscripts are the latest collected data.

3. A hydraulic system pressure precision control method according to claim 2, characterized in that: In S2, the latest error value replaces e_form[1] in the array e_form[1..N], and other data are shifted back in sequence according to the subscript number to complete the data iteration.

4. A hydraulic system pressure precision control method according to claim 2, characterized in that: In step S4, the jitter array shake[1..N] is obtained by subtraction.

5. A hydraulic system pressure precision control method according to claim 1, characterized in that: The range[1] and range[2] are both constants, and range[3..N] are backup values.

6. A hydraulic system pressure precision control method according to claim 1, characterized in that: The N is 10.

7. A hydraulic system pressure precision control method according to claim 1, characterized in that: In step S6, the data processor 1 determines the jitter.

8. A hydraulic system pressure precision control method according to claim 1, characterized in that: In step S6, if after all the jitter PID parameters have been tried, the jitter determination still cannot be exited, the test is terminated and an alarm is sounded to restart.

9. A hydraulic system pressure precision control method according to claim 1, characterized in that: The method further comprises using the data processor 2 to judge the sudden change of the tightening angle.

10. A hydraulic system pressure precision control method according to claim 9, characterized in that: The method for judging the sudden change of the tightening angle is as follows: take the value of e_form[1] and the value of e_form[2] in the array e_form[1..N], and calculate the difference between the two values; add the differential parameter Kd to obtain the gradient value; when the gradient value is greater than 3 times the jitter allowable band, it is determined that the tightening angle has undergone an instantaneous sudden change; when a sudden change occurs, the value of the integral link ei is directly and completely cleared, otherwise the integral continues to be superimposed.

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