Control method of thrust type hydraulic length adjusting device

Abstract

The invention provides a control method of a thrust type hydraulic length adjusting device, and belongs to the technical field of device control. The method comprises the following steps of: 1, establishing a piston cylinder data model based on a piston rodless cavity area, rodless cavity pressure intensity, a piston rod cavity area, rod cavity pressure intensity, a viscous damping coefficient, a piston movement speed, friction force and loading force of a piston cylinder of the thrust type hydraulic length adjusting device; 2, a closed-loop feedback system of a hydraulic system of the thrust type hydraulic length adjusting device is constructed, and closed-loop feedback control is executed; 3, flow regulation is conducted according to the total control quantity serving as a self-adaptive sliding mode control instruction; and 4, the pressure of the hydraulic pump is adjusted according to the pressure error of the rodless cavity of the piston cylinder. The defects that in the prior art, a hydraulic system of a thrust type hydraulic length adjusting device is low in response speed, the adjusting precision is affected by multiple factors, and high-precision length fine adjustment is difficult to achieve are effectively overcome.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of device control, and particularly relates to a control method of a thrust type hydraulic length adjusting device. BACKGROUND

[0002] At present, the thrust type hydraulic length adjusting device mentioned in the prior art solution with the patent publication number "CN119349406A" is widely applied in industrial production. However, the hydraulic system of the existing thrust type hydraulic length adjusting device generally has the problem of slow response speed, and it is difficult to meet the work scenes with high requirements on the adjusting timeliness. At the same time, the adjusting accuracy is affected by many factors, so that it is difficult to realize high-precision length fine adjustment in actual application, and the application in the field with high accuracy requirements is limited. SUMMARY

[0003] To solve the defects in the prior art, the application provides a control method of a thrust type hydraulic length adjusting device, which effectively avoids the defects of the existing thrust type hydraulic length adjusting device, such as slow response speed of the hydraulic system, adjusting accuracy affected by many factors, and difficulty in realizing high-precision length fine adjustment.

[0004] The application uses the following technical solutions.

[0005] A control method of a thrust type hydraulic length adjusting device, comprising:

[0006] Step 1: establishing a piston cylinder data model based on the piston rodless cavity area, rodless cavity pressure, piston rod cavity area, rod cavity pressure, viscous damping coefficient, piston movement speed, friction and load force of the piston cylinder of the thrust type hydraulic length adjusting device;

[0007] Step 2: constructing a closed-loop feedback system of the hydraulic system of the thrust type hydraulic length adjusting device and performing closed-loop feedback control;

[0008] Step 3: adjusting the flow according to the total control amount as an adaptive sliding mode control instruction

[0009] Step 4: adjusting the pressure of the hydraulic pump according to the rodless cavity pressure error of the piston cylinder.

[0010] Further, in step 1, the expression of the piston cylinder data model is:

[0011] ;

[0012] wherein T is the thrust generated by the piston cylinder, A is the piston rodless cavity area of the piston cylinder, P is the rodless cavity pressure of the piston cylinder,​ is the piston rod cavity area of ​​the piston cylinder, is the rod chamber pressure of the piston cylinder, is the viscous damping coefficient of the piston cylinder, is the piston speed of the piston cylinder, is the friction force of the piston cylinder, is the load force of the piston cylinder.

[0013] Furthermore, in step 1, the rodless chamber pressure of the piston cylinder is The pressure sensor connected to the controller collects and transmits it to the controller. The pressure sensor is set in the oil inlet pipeline of the rodless chamber of the piston cylinder. The pressure of the rod chamber of the piston cylinder is The pressure is collected by the second pressure sensor connected to the controller and transmitted to the controller. The second pressure sensor is set in the oil inlet pipeline of the rod chamber of the piston cylinder. The piston movement speed of the piston cylinder The speed sensor connected to the controller collects and transmits the data to the controller. The speed sensor is set on the piston rod of the piston cylinder. The load force of the piston cylinder The force is collected by the tension sensor and transmitted to the controller. The tension sensor is set at the connection between the load and the piston cylinder. The friction of the piston cylinder The thrust generated by the piston cylinder under no-load conditions .

[0014] Furthermore, in step 2, a method for constructing a closed-loop feedback system of a hydraulic system of a thrust-type hydraulic length adjustment device includes:

[0015] The displacement sensor connected to the controller is set on the piston rod of the piston cylinder of the thrust type hydraulic length adjustment device. The controller, proportional flow valve, proportional pressure valve, pressure sensor 1 and pressure sensor 2 constitute a closed-loop feedback system of the hydraulic system of the thrust type hydraulic length adjustment device. The displacement sensor collects the displacement of the piston rod and transmits it to the controller.

[0016] Furthermore, in step 2, the method of performing closed-loop feedback control includes:

[0017] Step 2-1: Filter the load force of the piston cylinder, the rodless chamber pressure of the piston cylinder, the rod chamber pressure of the piston cylinder, and the displacement of the piston rod transmitted to the controller;

[0018] Step 2-2: Calculate multi-dimensional error;

[0019] Step 2-3: Generate adaptive sliding mode control instructions.

[0020] Furthermore, in step 2-1, the load force of the piston cylinder, the rodless chamber pressure of the piston cylinder, the rod chamber pressure of the piston cylinder, and the displacement of the piston rod transmitted to the controller are filtered using an improved second-order Butterworth low-pass filter. The calculation formula of the improved second-order Butterworth low-pass filter is:

[0021] ;

[0022] in After filtering, Load force of piston cylinder , the rodless chamber pressure of the piston cylinder , the rod chamber pressure of the piston cylinder or the displacement of the piston rod, After filtering, Load force of piston cylinder , the rodless chamber pressure of the piston cylinder , the rod chamber pressure of the piston cylinder or the displacement of the piston rod, After filtering, Load force of piston cylinder , the rodless chamber pressure of the piston cylinder , the rod chamber pressure of the piston cylinder or the displacement of the piston rod, For the first Load force of piston cylinder , the rodless chamber pressure of the piston cylinder , the rod chamber pressure of the piston cylinder or the displacement of the piston rod, For the first Load force of piston cylinder , the rodless chamber pressure of the piston cylinder , the rod chamber pressure of the piston cylinder or the displacement of the piston rod, For the first Load force of piston cylinder , the rodless chamber pressure of the piston cylinder , the rod chamber pressure of the piston cylinder Or the displacement of the piston rod.

[0023] Furthermore, step 2-2 specifically includes:

[0024] Step 2-2-1: Calculate the displacement error;

[0025] Step 2-2-2: Calculate the error change rate using the difference method according to the following formula :

[0026] ,in is the sampling period of the displacement sensor, For the calculation of displacement error, For the calculation of displacement error;

[0027] Step 2-2-3: Perform pressure-assisted calibration.

[0028] Furthermore, in step 2-2-1, the method for calculating the displacement error includes:

[0029] The controller converts the actual displacement after filtering Displacement from the preset target In contrast, the displacement error is calculated according to the following formula :

[0030] .

[0031] Furthermore, step 2-2-3 specifically includes:

[0032] According to the rodless chamber pressure of the piston cylinder after filtering Rod chamber pressure of piston cylinder , combined with the piston cylinder data model to calculate the thrust generated by the piston cylinder , then the thrust generated by the piston cylinder and the load force of the piston cylinder after filtering In contrast, when When , the controller triggers the thrust abnormality warning.

[0033] Furthermore, steps 2-3 specifically include:

[0034] Step 2-3-1: Calculate the sliding surface variables, that is, based on the displacement error and the error change rate, calculate the sliding surface variables according to the following formula: :

[0035] ;

[0036] in are the set sliding surface parameters;

[0037] Step 2-3-2: Solve the control law;

[0038] Step 2-3-3: Calculate the total control quantity as the adaptive sliding mode control instruction , thereby achieving closed-loop feedback control.

[0039] Furthermore, step 2-3-2 specifically includes:

[0040] Step 2-3-2-1: Solve the equivalent control law , whose expression is ,in is the stiffness coefficient of the piston cylinder.

[0041] Step 2-3-2-2: Solve the switching control law , whose expression is , where the switching gain , and They are the set coefficients one and two respectively.

[0042] Furthermore, in step 2-3-3, the total control amount The calculation formula is:

[0043] ;

[0044] in is the voltage regulation corresponding to unit force; is the voltage regulation amount corresponding to unit speed.

[0045] Furthermore, step 3 specifically includes:

[0046] The controller will be used as the total control quantity of the adaptive sliding mode control instruction The proportional flow valve is provided at the outlet of the hydraulic pump, so that the working voltage of the proportional flow valve is .

[0047] Furthermore, step 4 specifically includes:

[0048] Step 4-1: Calculate target pressure , whose expression is: ,in is the required thrust of the piston cylinder under the current working conditions;

[0049] Step 4-2: The controller calculates the rodless chamber pressure error of the piston cylinder every 1ms , whose expression is: ;

[0050] Step 4-3: Set the adjustment threshold ,when When the proportional pressure valve is not adjusted, the current working current of the proportional pressure valve is maintained. When the pressure regulating mechanism is triggered;

[0051] Step 4-4: When the pressure regulation mechanism is triggered, the controller adjusts the current working current of the proportional pressure valve to , and its calculation equation is:

[0052] ,in is the minimum pressure value output by the hydraulic pump, is the maximum pressure value output by the hydraulic pump, The minimum operating current of the proportional pressure valve corresponding to the minimum pressure value output by the hydraulic pump, The maximum operating current of the proportional pressure valve corresponding to the maximum pressure value output by the hydraulic pump.

[0053] Furthermore, the hydraulic system of the thrust type hydraulic length adjustment device includes a piston cylinder of the thrust type hydraulic length adjustment device, an oil storage tank, and a pipeline connecting the piston cylinder and the oil storage tank. The pipeline is provided with a hydraulic pump connected to the controller, and the outlet of the hydraulic pump is provided with a proportional flow valve and a proportional pressure valve connected to the controller.

[0054] The beneficial effects of the present invention are as follows:

[0055] Significantly improved response speed: By adopting an advanced adaptive sliding mode control algorithm and building a closed-loop feedback system, it can quickly respond to errors in the hydraulic system of the thrust-type hydraulic length adjuster and adjust the control strategy in real time, enabling the thrust-type hydraulic length adjuster to quickly reach the target length. This greatly shortens the adjustment time and meets the requirements of work scenarios with high response speed requirements.

[0056] Effectively improve adjustment accuracy: The precise mathematical model can fully consider the impact of various factors on adjustment accuracy. Through real-time monitoring and compensation, it effectively reduces the interference of multiple factors. Combined with closed-loop feedback control, high-precision length fine-tuning is achieved, which improves the applicability of the thrust-type hydraulic length adjustment device in areas with stringent precision requirements.

[0057] Enhanced system robustness: The adaptive sliding mode control algorithm can automatically adjust control parameters according to the real-time status of the hydraulic system, has a strong ability to suppress the uncertainty and interference of the hydraulic system, enhances the stability and reliability of the hydraulic system under complex working conditions, and improves the overall performance of the thrust-type hydraulic length adjustment device. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 It is a flow chart of the control method of the push-type hydraulic length adjustment device in the present invention. DETAILED DESCRIPTION

[0059] To make the objectives, technical solutions, and advantages of the present invention more clear, the following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely express the technical solutions of the present invention. The embodiments expressed in this application are only part of the embodiments of the present invention, not all of the embodiments. Based on the spirit of the present invention, other embodiments obtained by ordinary technicians in this field without making creative work are all within the scope of protection of the present invention.

[0060] like Figure 1 As shown, a control method of a thrust type hydraulic length adjustment device includes:

[0061] Step 1: Establish a piston cylinder data model based on the piston rodless cavity area, rodless cavity pressure, piston rod cavity area, rod cavity pressure, viscous damping coefficient, piston movement speed, friction force and load force of the piston cylinder of the thrust type hydraulic length adjustment device;

[0062] In a preferred but non-limiting embodiment of the present invention, in step 1, the expression of the piston-cylinder data model is:

[0063] ;

[0064] in is the thrust generated by the piston cylinder, is the rodless cavity area of ​​the piston cylinder, is the rodless chamber pressure of the piston cylinder, is the piston rod cavity area of ​​the piston cylinder, is the rod chamber pressure of the piston cylinder, is the viscous damping coefficient of the piston cylinder, is the piston speed of the piston cylinder, is the friction force of the piston cylinder, is the load force of the piston cylinder. By accurately solving this piston cylinder data model, we can accurately predict the output characteristics of the piston cylinder of the thrust-type hydraulic length adjustment device under different working conditions, providing a theoretical basis for the subsequent control strategy formulation.

[0065] In a preferred but non-limiting embodiment of the present invention, in step 1, the viscous damping coefficient of the piston cylinder is The rodless chamber pressure of the piston cylinder can be obtained through experiments. The pressure sensor connected to the controller collects and transmits it to the controller. The pressure sensor is set in the oil inlet pipeline of the rodless chamber of the piston cylinder. The pressure of the rod chamber of the piston cylinder is The pressure is collected by the second pressure sensor connected to the controller and transmitted to the controller. The second pressure sensor is set in the oil inlet pipeline of the rod chamber of the piston cylinder. The piston movement speed of the piston cylinder The speed sensor connected to the controller collects and transmits the data to the controller. The speed sensor is set on the piston rod of the piston cylinder. The load force of the piston cylinder The force is collected by the tension sensor and transmitted to the controller. The tension sensor is set at the connection between the load and the piston cylinder. The friction of the piston cylinder The thrust generated by the piston cylinder under no-load conditions .

[0066] Step 2: Constructing a closed-loop feedback system for the hydraulic system of the thrust-type hydraulic length adjustment device and performing closed-loop feedback control;

[0067] In a preferred but non-limiting embodiment of the present invention, in step 2, a method for constructing a closed-loop feedback system of a hydraulic system of a thrust-type hydraulic length adjustment device comprises:

[0068] The displacement sensor connected to the controller is set on the piston rod of the piston cylinder of the thrust type hydraulic length adjustment device. The controller, proportional flow valve, proportional pressure valve, pressure sensor 1 and pressure sensor 2 constitute a closed-loop feedback system of the hydraulic system of the thrust type hydraulic length adjustment device. The displacement sensor collects the displacement of the piston rod and transmits it to the controller.

[0069] The displacement sensor should be a grating or magnetostrictive displacement sensor with a resolution of ≥0.1μm and a sampling frequency of ≥1kHz to ensure high-precision fine-tuning. Models with an IP67 protection rating or higher are preferred to withstand oil, dirt, and dust in industrial environments.

[0070] In a preferred but non-limiting embodiment of the present invention, in step 2, the method of performing closed-loop feedback control includes:

[0071] Step 2-1: Filter the load force of the piston cylinder, the rodless chamber pressure of the piston cylinder, the rod chamber pressure of the piston cylinder, and the displacement of the piston rod transmitted to the controller;

[0072] In a preferred but non-limiting embodiment of the present invention, in step 2-1, the piston cylinder load force, the piston cylinder rodless chamber pressure, the piston cylinder rod chamber pressure, and the piston rod displacement transmitted to the controller are filtered using an improved second-order Butterworth low-pass filter, with cutoff frequencies set at 50 Hz (displacement) and 100 Hz (pressure and load force). This filter removes high-frequency noise generated by the hydraulic system vibration of the thrust-type hydraulic length adjustment device. The calculation formula for the improved second-order Butterworth low-pass filter is:

[0073] ;

[0074] in After filtering, Load force of piston cylinder , the rodless chamber pressure of the piston cylinder , the rod chamber pressure of the piston cylinder or the displacement of the piston rod, After filtering, Load force of piston cylinder , the rodless chamber pressure of the piston cylinder , the rod chamber pressure of the piston cylinder or the displacement of the piston rod, After filtering, Load force of piston cylinder , the rodless chamber pressure of the piston cylinder , the rod chamber pressure of the piston cylinder or the displacement of the piston rod, For the first Load force of piston cylinder , the rodless chamber pressure of the piston cylinder , the rod chamber pressure of the piston cylinder or the displacement of the piston rod, For the first Load force of piston cylinder , the rodless chamber pressure of the piston cylinder , the rod chamber pressure of the piston cylinder or the displacement of the piston rod, For the first Load force of piston cylinder , the rodless chamber pressure of the piston cylinder , the rod chamber pressure of the piston cylinder Or the displacement of the piston rod.

[0075] 0.0234 is and The weight of , 0.0469 is The weights satisfy 0.0234+0.0469+0.0234=0.0937, which reflects the "low-pass weighting" of recent signals, that is, by reducing the weight of high-frequency signals (high-frequency signals change dramatically at adjacent moments and cancel each other out after weighting), the trend of low-frequency signals is retained (low-frequency signals change smoothly at adjacent moments and are superimposed and enhanced after weighting).

[0076] Step 2-2: Calculate multi-dimensional error;

[0077] In a preferred but non-limiting embodiment of the present invention, step 2-2 specifically comprises:

[0078] Step 2-2-1: Calculate the displacement error;

[0079] In a preferred but non-limiting embodiment of the present invention, in step 2-2-1, the method for calculating the displacement error includes:

[0080] The controller converts the actual displacement after filtering (Unit: m) Displacement from the preset target (Unit: m) Compare and calculate the displacement error according to the following formula :

[0081] .

[0082] Step 2-2-2: Calculate the error change rate using the difference method according to the following formula :

[0083] ,in is the sampling period of the displacement sensor, For the calculation of displacement error, For the calculation of displacement error;

[0084] Step 2-2-3: Perform pressure-assisted calibration.

[0085] In a preferred but non-limiting embodiment of the present invention, step 2-2-3 specifically includes:

[0086] According to the rodless chamber pressure of the piston cylinder after filtering Rod chamber pressure of piston cylinder , combined with the piston cylinder data model to calculate the thrust generated by the piston cylinder , then the thrust generated by the piston cylinder and the load force of the piston cylinder after filtering In contrast, when When the controller triggers the thrust abnormality warning, the controller sends a thrust abnormality warning message to the display screen connected to it for display.

[0087] Step 2-3: Generate adaptive sliding mode control instructions.

[0088] In a preferred but non-limiting embodiment of the present invention, steps 2-3 specifically include:

[0089] Step 2-3-1: Calculate the sliding surface variables, that is, based on the displacement error and the error change rate, calculate the sliding surface variables according to the following formula: :

[0090] ;

[0091] in For the set sliding surface parameters, the sliding surface parameters are set according to specific requirements, for example may be 10 (unit: 1 / s), reflects the degree of deviation of the hydraulic system from the ideal trajectory;

[0092] Step 2-3-2: Solve the control law;

[0093] In the preferred but non-limiting embodiment of the present application, step 2-3-2 specifically includes:

[0094] Step 2-3-2-1: Solve the equivalent control law , that is, solve it by linearizing the mathematical model, and its expression is , where is the stiffness coefficient of the piston cylinder (calibrated by experiment).

[0095] Step 2-3-2-2: Solve the switching control law , that is, adopt an adaptive gain adjustment strategy, and its expression is , where the switching gain , and are respectively set coefficient one and coefficient two, which can be set according to specific requirements, just as may be 5, may be 0.1, and by increasing in real time, it ensures that the hydraulic system quickly approaches the sliding surface.

[0096] Step 2-3-3: Calculate the total control amount as an adaptive sliding mode control instruction , so as to realize closed-loop feedback control.

[0097] In the preferred but non-limiting embodiment of the present application, in step 2-3-3, the calculation formula of the total control amount is:

[0098] ;

[0099] , where is the voltage adjustment amount corresponding to a unit of force, which is calibrated by experiment (for example, when the load force changes by 1000N, a voltage adjustment of 2V is required, then = 0.002V / N); is the voltage adjustment amount corresponding to a unit of speed, which is calibrated by experiment (for example, when the speed of the piston rod changes by 0.01m / s, a voltage adjustment of 0.1V is required, then = 10VA*s / m).

[0100] Step 3: Perform flow regulation according to the total control amount as an adaptive sliding mode control instruction .

[0101] In a preferred but non-limiting embodiment of the present invention, step 3 specifically comprises:

[0102] The controller will be used as the total control quantity of the adaptive sliding mode control instruction The proportional flow valve is provided at the outlet of the hydraulic pump, so that the working voltage of the proportional flow valve is Among them, the flow valve control signal and In direct proportion.

[0103] During flow regulation, when When u increases, the opening of the proportional flow valve increases, and the output flow Q of the hydraulic pump increases linearly according to Q=Qmax×u / 10 (Qmax is the maximum flow of the hydraulic pump), pushing the piston cylinder to accelerate; when u decreases, the flow decreases and the piston cylinder decelerates.

[0104] Step 4: Adjust the pressure of the hydraulic pump according to the rodless chamber pressure error of the piston cylinder.

[0105] In a preferred but non-limiting embodiment of the present invention, step 4 specifically comprises:

[0106] Step 4-1: Calculate target pressure , whose expression is: ,in The required thrust of the piston cylinder under the current working condition, which is preset according to the load characteristics;

[0107] Step 4-2: The controller calculates the rodless chamber pressure error of the piston cylinder every 1ms , whose expression is: ;

[0108] Step 4-3: To avoid frequent adjustments, set the error dead zone and thus set the adjustment threshold , adjust the threshold It can be set to a value greater than zero according to specific requirements, which ensures the pressure accuracy is within Within, as It can be 0.05MPa. When the proportional pressure valve is not adjusted, the current working current of the proportional pressure valve is maintained. When the pressure regulating mechanism is triggered;

[0109] Step 4-4: When the pressure regulation mechanism is triggered, the controller adjusts the current working current of the proportional pressure valve to , and its calculation equation is:

[0110] ,in is the minimum pressure value output by the hydraulic pump, is the maximum pressure value output by the hydraulic pump, The minimum operating current of the proportional pressure valve corresponding to the minimum pressure value output by the hydraulic pump, The maximum operating current of the proportional pressure valve corresponding to the maximum pressure value output by the hydraulic pump.

[0111] According to this calculation equation, the current working current of the proportional pressure valve can be obtained. As a result, the proportional pressure valve can be accurately corrected according to the rodless chamber pressure error, so that the actual pressure dynamically tracks the target pressure and provides stable thrust for the piston cylinder.

[0112] Through the above-mentioned specific method, accurate acquisition of sensor signals, efficient execution of control algorithms and precise adjustment of hydraulic pumps can be achieved, effectively reducing the interference of multiple factors, and ultimately building a stable and reliable closed-loop feedback system, significantly improving the adjustment accuracy and response speed of the device.

[0113] In a preferred but non-limiting embodiment of the present invention, the hydraulic system of the thrust-type hydraulic length adjuster includes a piston cylinder of the thrust-type hydraulic length adjuster, an oil storage tank, and a pipeline connecting the piston cylinder and the oil storage tank. The pipeline is provided with a hydraulic pump connected to a controller, and the outlet of the hydraulic pump is provided with a proportional flow valve and a proportional pressure valve connected to the controller. The controller may be a PLC controller.

[0114] The beneficial effects of the present invention are as follows:

[0115] Significantly improved response speed: By adopting an advanced adaptive sliding mode control algorithm and building a closed-loop feedback system, it can quickly respond to errors in the hydraulic system of the thrust-type hydraulic length adjuster and adjust the control strategy in real time, enabling the thrust-type hydraulic length adjuster to quickly reach the target length. This greatly shortens the adjustment time and meets the requirements of work scenarios with high response speed requirements.

[0116] Effectively improve adjustment accuracy: The precise mathematical model can fully consider the impact of various factors on adjustment accuracy. Through real-time monitoring and compensation, it effectively reduces the interference of multiple factors. Combined with closed-loop feedback control, high-precision length fine-tuning is achieved, which improves the applicability of the thrust-type hydraulic length adjustment device in areas with stringent precision requirements.

[0117] Enhanced system robustness: The adaptive sliding mode control algorithm can automatically adjust control parameters according to the real-time status of the hydraulic system, has a strong ability to suppress the uncertainty and interference of the hydraulic system, enhances the stability and reliability of the hydraulic system under complex working conditions, and improves the overall performance of the thrust-type hydraulic length adjustment device.

[0118] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not deviate from the spirit and scope of the present invention should be covered within the protection space of the claims of the present invention.

Claims

1. A control method for a thrust type hydraulic length adjustment device, characterized in that: include: Step 1: Establish a piston cylinder data model based on the piston rodless cavity area, rodless cavity pressure, piston rod cavity area, rod cavity pressure, viscous damping coefficient, piston movement speed, friction force and load force of the piston cylinder of the thrust type hydraulic length adjustment device; Step 2: Constructing a closed-loop feedback system for the hydraulic system of the thrust-type hydraulic length adjustment device and performing closed-loop feedback control; Step 3: Based on the total control quantity as the adaptive sliding mode control instruction Perform flow regulation; Step 4: Adjust the pressure of the hydraulic pump according to the rodless chamber pressure error of the piston cylinder.

2. The control method of the thrust type hydraulic length adjustment device according to claim 1, characterized in that: In step 1, the expression of the piston-cylinder data model is: ； in is the thrust generated by the piston cylinder, is the rodless cavity area of ​​the piston cylinder, is the rodless chamber pressure of the piston cylinder, is the piston rod cavity area of ​​the piston cylinder, is the rod chamber pressure of the piston cylinder, is the viscous damping coefficient of the piston cylinder, is the piston speed of the piston cylinder, is the friction force of the piston cylinder, is the load force of the piston cylinder; In step 1, the rodless chamber pressure of the piston cylinder is The pressure sensor connected to the controller collects and transmits it to the controller. The pressure sensor is set in the oil inlet pipeline of the rodless chamber of the piston cylinder. The pressure of the rod chamber of the piston cylinder is The pressure is collected by the second pressure sensor connected to the controller and transmitted to the controller. The second pressure sensor is set in the oil inlet pipeline of the rod chamber of the piston cylinder. The piston movement speed of the piston cylinder The speed sensor connected to the controller collects and transmits the speed to the controller. The speed sensor is set on the piston rod of the piston cylinder. The load force of the piston cylinder The force is collected by the tension sensor and transmitted to the controller. The tension sensor is set at the connection between the load and the piston cylinder. The friction of the piston cylinder The thrust generated by the piston cylinder under no-load conditions .

3. The control method of the thrust type hydraulic length adjustment device according to claim 2, characterized in that: In step 2, a method for constructing a closed-loop feedback system of a hydraulic system of a thrust-type hydraulic length adjustment device includes: The displacement sensor connected to the controller is set on the piston rod of the piston cylinder of the thrust type hydraulic length adjustment device. The controller, proportional flow valve, proportional pressure valve, pressure sensor 1 and pressure sensor 2 constitute a closed-loop feedback system of the hydraulic system of the thrust type hydraulic length adjustment device. The displacement sensor collects the displacement of the piston rod and transmits it to the controller.

4. The control method of the thrust type hydraulic length adjustment device according to claim 3, characterized in that: In step 2, a closed-loop feedback control method is performed, including: Step 2-1: Filter the load force of the piston cylinder, the rodless chamber pressure of the piston cylinder, the rod chamber pressure of the piston cylinder, and the displacement of the piston rod transmitted to the controller; Step 2-2: Calculate multi-dimensional error; Step 2-3: Generate adaptive sliding mode control instructions.

5. The control method of the thrust type hydraulic length adjustment device according to claim 4, characterized in that: In step 2-1, the load force of the piston cylinder, the rodless chamber pressure of the piston cylinder, the rod chamber pressure of the piston cylinder, and the displacement of the piston rod transmitted to the controller are filtered using an improved second-order Butterworth low-pass filter. The calculation formula of the improved second-order Butterworth low-pass filter is: ； in After filtering, Load force of piston cylinder , the rodless chamber pressure of the piston cylinder , the rod chamber pressure of the piston cylinder or the displacement of the piston rod, After filtering, Load force of piston cylinder , the rodless chamber pressure of the piston cylinder , the rod chamber pressure of the piston cylinder or the displacement of the piston rod, After filtering, Load force of piston cylinder , the rodless chamber pressure of the piston cylinder , the rod chamber pressure of the piston cylinder or the displacement of the piston rod, For the first Load force of piston cylinder , the rodless chamber pressure of the piston cylinder , the rod chamber pressure of the piston cylinder or the displacement of the piston rod, For the first Load force of piston cylinder , the rodless chamber pressure of the piston cylinder , the rod chamber pressure of the piston cylinder or the displacement of the piston rod, For the first Load force of piston cylinder , the rodless chamber pressure of the piston cylinder , the rod chamber pressure of the piston cylinder Or the displacement of the piston rod.

6. The control method of the thrust type hydraulic length adjustment device according to claim 5, characterized in that: Step 2-2 specifically includes: Step 2-2-1: Calculate the displacement error; Step 2-2-2: Calculate the error change rate using the difference method according to the following formula : ,in is the sampling period of the displacement sensor, For the calculation of displacement error, For the calculation of displacement error; Step 2-2-3: Perform pressure-assisted calibration.

7. The control method of the thrust type hydraulic length adjustment device according to claim 6, characterized in that: In step 2-2-1, the method for calculating the displacement error includes: The controller converts the actual displacement after filtering Displacement from the preset target In contrast, the displacement error is calculated according to the following formula : ； Step 2-2-3 specifically includes: According to the rodless chamber pressure of the piston cylinder after filtering Rod chamber pressure of piston cylinder , combined with the piston cylinder data model to calculate the thrust generated by the piston cylinder , then the thrust generated by the piston cylinder and the load force of the piston cylinder after filtering In contrast, when When , the controller triggers the thrust abnormality warning.

8. The control method of the thrust type hydraulic length adjustment device according to claim 7, characterized in that: Steps 2-3 specifically include: Step 2-3-1: Calculate the sliding surface variables, that is, based on the displacement error and the error change rate, calculate the sliding surface variables according to the following formula: : ； in are the set sliding surface parameters; Step 2-3-2: Solve the control law; Step 2-3-3: Calculate the total control quantity as the adaptive sliding mode control instruction , thereby realizing closed-loop feedback control; Step 2-3-2 specifically includes: Step 2-3-2-1: Solve the equivalent control law , whose expression is ,in is the stiffness coefficient of the piston cylinder; Step 2-3-2-2: Solve the switching control law , whose expression is , where the switching gain , and They are the set coefficients one and two respectively; In step 2-3-3, the total control amount The calculation formula is: ； in is the voltage regulation corresponding to unit force; is the voltage regulation amount corresponding to unit speed.

9. The control method of the thrust type hydraulic length adjustment device according to claim 8, characterized in that: Step 3 specifically includes: The controller will be used as the total control quantity of the adaptive sliding mode control instruction The proportional flow valve is provided at the outlet of the hydraulic pump, so that the working voltage of the proportional flow valve is ; Step 4 specifically includes: Step 4-1: Calculate target pressure , whose expression is: ,in is the required thrust of the piston cylinder under the current working conditions; Step 4-2: The controller calculates the rodless chamber pressure error of the piston cylinder every 1ms , whose expression is: ; Step 4-3: Set the adjustment threshold ,when When the proportional pressure valve is not adjusted, the current working current of the proportional pressure valve is maintained. When the pressure regulating mechanism is triggered; Step 4-4: When the pressure regulation mechanism is triggered, the controller adjusts the current working current of the proportional pressure valve to , and its calculation equation is: ,in is the minimum pressure value output by the hydraulic pump, is the maximum pressure value output by the hydraulic pump, The minimum operating current of the proportional pressure valve corresponding to the minimum pressure value output by the hydraulic pump, The maximum operating current of the proportional pressure valve corresponding to the maximum pressure value output by the hydraulic pump.

10. The control method of the thrust type hydraulic length adjustment device according to claim 9, characterized in that: The hydraulic system of the thrust type hydraulic length adjustment device includes a piston cylinder of the thrust type hydraulic length adjustment device, an oil storage tank, and a pipeline connecting the piston cylinder and the oil storage tank. A hydraulic pump connected to a controller is provided on the pipeline, and a proportional flow valve and a proportional pressure valve connected to the controller are provided at the outlet of the hydraulic pump.

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