Force feedback signal reconstruction method of hydraulic cylinder

Abstract

The invention relates to the technical field of hydraulic control and testing, and discloses a force feedback signal reconstruction method of a hydraulic cylinder, which comprises the following steps: acquiring the actual displacement of a test sample piece by using a displacement sensor of the hydraulic cylinder, and calculating the theoretical load value of the test sample piece in combination with the theoretical rigidity of the test sample piece; acquiring a force feedback signal of the hydraulic cylinder by using a force sensor of the hydraulic cylinder, and performing band-pass filtering by using a band-pass filter; drawing a load displacement hysteretic curve after band-pass filtering by taking the actual displacement of the test sample as a horizontal coordinate and the force feedback signal after band-pass filtering as a vertical coordinate; the maximum displacement point on the load displacement hysteresis curve after band-pass filtering is obtained, the maximum real load acting on the test sample piece by the hydraulic cylinder is obtained, and the load time history actually acting on the test sample piece by the hydraulic cylinder is reconstructed; according to the method, the influence of the friction force of the hydraulic cylinder on the force feedback signal is eliminated, the real load loaded on the test sample by the hydraulic cylinder is accurately restored, and the reliability of the test result is improved.

Description

Technical Field

[0001] The invention relates to the technical field of hydraulic control and testing, and in particular to a method for reconstructing a force feedback signal of a hydraulic cylinder. Background Art

[0002] Hydraulic cylinders have the advantages of strong load capacity and fast response speed, so they are widely used in various test systems. For example, shock absorber dynamic simulation test benches and vehicle motion posture simulation test benches all complete loading tests through hydraulic cylinders.

[0003] The working principle of the hydraulic cylinder is to push the hydraulic cylinder piston rod to telescope in the cylinder body through the pressure formed by the hydraulic oil, thereby completing the loading of the test system. The hydraulic cylinder piston rod and the cylinder body are usually sealed, and the friction between the two is the main factor affecting the reliability of the test system. A force sensor is usually set at the end of the hydraulic cylinder to collect the force signal during the loading process, and the force signal is fed back to the control system. The control system will adjust and compensate the control command after comparing the command signal with the feedback signal. However, in addition to the load actually loaded on the test sample, the feedback force signal also contains the friction between the hydraulic cylinder piston rod and the cylinder body, which will cause the control system to give wrong loading instructions and increase the test error. In addition, the force signal and displacement signal fed back by the hydraulic cylinder are often used to calculate various parameters of the test sample. For example, when conducting a spring stiffness measurement test, the ratio of the force signal and the displacement signal fed back by the hydraulic cylinder can be used to obtain the important parameter of the spring stiffness. However, when the feedback force signal contains the friction of the hydraulic cylinder itself, it will directly affect the spring stiffness test result. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a method for reconstructing a hydraulic cylinder force feedback signal, which eliminates the influence of the hydraulic cylinder's own friction force from the force feedback signal of the hydraulic cylinder and restores the actual load loaded by the test system onto the test sample, thereby solving the problems of large experimental errors and low experimental accuracy caused by loading tests using hydraulic cylinders in the prior art.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0006] A method for reconstructing a force feedback signal of a hydraulic cylinder comprises the following steps:

[0007] S1. Use the displacement sensor of the hydraulic cylinder to collect the actual displacement of the test sample, and calculate the theoretical load value of the test sample in combination with the theoretical stiffness of the test sample;

[0008] S2, using the force sensor of the hydraulic cylinder to collect the force feedback signal of the hydraulic cylinder;

[0009] Among them, the force feedback signal of the hydraulic cylinder includes the friction force of the hydraulic cylinder itself and the real load of the hydraulic cylinder acting on the test sample;

[0010] S3, designing a bandpass filter according to the loading frequency, and using the bandpass filter to perform bandpass filtering on the force feedback signal of the hydraulic cylinder to obtain a force feedback signal after bandpass filtering;

[0011] S4. Using the actual displacement of the test sample as the abscissa and the force feedback signal after bandpass filtering as the ordinate, draw a load-displacement hysteresis curve after bandpass filtering;

[0012] S5, obtaining the maximum displacement point on the load-displacement hysteresis curve after bandpass filtering, and obtaining the maximum true load of the hydraulic cylinder acting on the test sample;

[0013] S6. According to the maximum true load and loading frequency of the hydraulic cylinder acting on the test sample, the load time history of the hydraulic cylinder actually acting on the test sample is reconstructed to obtain a reconstructed force feedback signal of the hydraulic cylinder.

[0014] Furthermore, the calculation formula of the theoretical load value of the test sample in step S1 is:

[0015] F t =K t ·Δx

[0016] Among them, F t Indicates the theoretical load value of the test specimen, K t represents the theoretical stiffness of the test specimen, and Δx represents the actual displacement of the test specimen.

[0017] Furthermore, step S3 specifically includes:

[0018] S31, obtaining the lower cutoff frequency and the upper cutoff frequency of the loading frequency, setting the filter order and selecting the filter type as a bandpass filter, and calculating the transfer function numerator coefficient and the transfer function denominator coefficient of the bandpass filter;

[0019] S32. Performing bandpass filtering on the force feedback signal of the hydraulic cylinder using the bandpass filter according to the numerator coefficient and the denominator coefficient of the transfer function of the bandpass filter to obtain a force feedback signal after bandpass filtering.

[0020] Furthermore, in step S31, the calculation formula of the transfer function numerator coefficient and the transfer function denominator coefficient of the bandpass filter is:

[0021] [b,a]=butter(N,f min ,f max ,′bandpass′)

[0022] Where b represents the numerator coefficient of the transfer function of the bandpass filter, a represents the denominator coefficient of the transfer function of the bandpass filter, butter represents the filter design function, N represents the filter order, and f min Indicates the lower cutoff frequency of the loading frequency, f max It indicates the upper cutoff frequency of the loading frequency, and bandpass indicates the type of filter.

[0023] Furthermore, the force feedback signal after bandpass filtering in step S32 is:

[0024] F band =filter(b,a,F ori )

[0025] Among them, F band represents the force feedback signal after bandpass filtering, fikter represents the filter function, F ori Represents the force feedback signal of the hydraulic cylinder.

[0026] Furthermore, the force feedback signal of the hydraulic cylinder reconstructed in step S6 is:

[0027] F r =A m ·sin(2·π·f·t)

[0028] Among them, F r represents the reconstructed hydraulic cylinder force feedback signal, A m represents the maximum load of the hydraulic cylinder on the test specimen, sin represents the sine function, f represents the loading frequency, and t represents the loading time.

[0029] The present invention has the following beneficial effects:

[0030] A hydraulic cylinder force feedback signal reconstruction method proposed in the present invention eliminates the influence of the hydraulic cylinder friction force on the force feedback signal, and quickly and accurately restores the real load loaded by the hydraulic cylinder on the test sample, greatly improving the reliability of the test results; at the same time, this force signal reconstruction process is simple and convenient, easy to program, and can be quickly transplanted into the test data processing program for data processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic flow chart of a hydraulic cylinder force feedback signal reconstruction method proposed by the present invention;

[0032] Figure 2 It is a schematic diagram of the axial side of the dynamic stiffness test bench of the helical spring group driven by the hydraulic cylinder in the embodiment;

[0033] Figure 3It is a front view schematic diagram of a dynamic stiffness measurement test bench of a coil spring group driven by a hydraulic cylinder in the embodiment;

[0034] Figure 4 Schematic diagram of the structure of the coil spring group in the embodiment;

[0035] Figure 5 It is a structural schematic diagram of the hydraulic cylinder in the embodiment;

[0036] Figure 6 The displacement signal of the test system fed back by the displacement sensor of the hydraulic cylinder in the embodiment;

[0037] Figure 7 Schematic diagram of theoretical load of the coil spring group in the embodiment;

[0038] Figure 8 Schematic diagram of actual force feedback signal of the hydraulic cylinder in the embodiment;

[0039] Fig. 9 is a force feedback signal after conventional bandpass filtering in the embodiment;

[0040] Fig.10 Schematic diagram for comparing the theoretical load-displacement hysteresis curve, the actual load-displacement hysteresis curve, and the load-displacement hysteresis curve after bandpass filtering of the test sample in the embodiment;

[0041] Fig.11 Schematic diagram of comparison between the load time history obtained after reconstruction in the embodiment and the theoretical load time history of the test sample. DETAILED DESCRIPTION

[0042] The specific implementation modes of the present invention are described below to facilitate those skilled in the art to understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0043] like Figure 1 As shown, a method for reconstructing a force feedback signal of a hydraulic cylinder includes the following steps S1-S6:

[0044] S1. Use the displacement sensor of the hydraulic cylinder to collect the actual displacement of the test sample, and calculate the theoretical load value of the test sample in combination with the theoretical stiffness of the test sample.

[0045] Specifically, the calculation formula of the theoretical load value of the test sample in step S1 is:

[0046] F t =K t ·Δx

[0047] Among them, F t Indicates the theoretical load value of the test specimen, K t represents the theoretical stiffness of the test specimen, and Δx represents the actual displacement of the test specimen.

[0048] In this embodiment, a coil spring group with known stiffness is selected as a test sample. The theoretical stiffness of the coil spring group is 1.55MN / m and has good linearity. The coil spring group is loaded by a hydraulic cylinder, that is, a dynamic stiffness measurement test bench (test system) of a coil spring group driven by a hydraulic cylinder is constructed to test the stiffness of the coil spring group. By eliminating the influence of the friction of the hydraulic cylinder itself from the force feedback signal of the hydraulic cylinder, the actual load loaded on the test sample by the test system is restored, thereby reducing the error of the test system and improving the test accuracy. Among them, the purpose of selecting a coil spring group with known stiffness as a test sample is that the theoretical load on the coil spring group can be calculated from the measured displacement (actual displacement) of the coil spring group and the known theoretical stiffness, which can be used as a standard reference value. Otherwise, there is a lack of a reference, and it is impossible to compare the gap between the actual feedback force signal of the hydraulic cylinder and the theoretical value, and finally it is impossible to verify whether the reconstructed load has truly eliminated the influence of friction.

[0049] like Figure 2-Figure 3 As shown, they are the isometric view and front view of the dynamic stiffness test bench for the coil spring group driven by the hydraulic cylinder; Figure 2-Figure 3 In the figure, 1 is the test bench base of the test system, 2 is the column, 3 is the cross beam, 4 is the hydraulic cylinder piston rod, 5 is the cylinder body of the hydraulic cylinder, 6 is the displacement sensor, 7 is the force sensor, 8 is the upper transition plate, 9 is the lower transition plate, and 10 is the coil spring group; and the test bench base provides support for the entire test system; the frame structure composed of the column 2 and the cross beam 3 provides a restraining reaction force for the test system; the cylinder body 5 of the hydraulic cylinder is suspended under the cross beam 3, and the hydraulic cylinder piston rod 4 is matched with the inside of the cylinder body 5, and the internal cavity of the cylinder body 5 is filled with hydraulic oil, and the pressure formed by the hydraulic oil pushes the hydraulic cylinder piston rod 4 to move; the end of the hydraulic cylinder piston rod 4 is connected to the upper surface of the upper transition plate 8, and a coil spring group 10 is installed between the upper transition plate 8 and the lower transition plate 9, and the lower transition plate 9 is installed on the upper surface of the test bench base 1; and the coil spring group 10 is composed of 8 coil steel springs installed side by side, and its structure is as shown in Figure 4 As shown; wherein the hydraulic cylinder includes a hydraulic cylinder piston rod 4, a hydraulic cylinder body 5, a displacement sensor 6, and a force sensor 7, and its structure is as shown Figure 5As shown; and the hydraulic control system drives the hydraulic cylinder piston rod 4 to move downward to apply pressure to the tested coil spring group 10, and the movement displacement of the hydraulic cylinder piston rod 4 is the same as that of the coil spring group 10, the displacement can be directly obtained by the displacement sensor 6 at the tail of the cylinder body, and the load applied by the hydraulic cylinder can be obtained by the force sensor 7 at the end of the hydraulic cylinder piston rod.

[0050] In addition, a standard sinusoidal loading command was used during the dynamic stiffness test of the coil spring group, such as Figure 6 As shown, Figure 6 The actual displacement of the coil spring group fed back by the displacement sensor at the rear of the hydraulic cylinder during the test is shown. Therefore, based on the actual displacement and the theoretical stiffness of the coil spring group, the theoretical value of the load on the coil spring group can be calculated, as shown in the figure below: Figure 7 shown.

[0051] S2. Using the force sensor of the hydraulic cylinder to collect the force feedback signal of the hydraulic cylinder; wherein the force feedback signal of the hydraulic cylinder includes the friction force of the hydraulic cylinder itself and the real load of the hydraulic cylinder acting on the test sample.

[0052] In this embodiment, due to the influence of the friction force of the hydraulic cylinder itself, the real force signal fed back by the force sensor at the end of the hydraulic cylinder piston rod is no longer a standard simple harmonic signal. Figure 8 As shown, and through analysis Figure 8 It can be seen that the friction effect of the hydraulic cylinder can be divided into two stages, specifically: the first stage: when the movement speed is close to zero, it is also the moment when the movement direction changes. The lubrication between the hydraulic cylinder piston rod and the cylinder body is insufficient, and the friction of the hydraulic cylinder is manifested as static friction. In this stage, the force feedback signal of the hydraulic cylinder will be suddenly raised due to the superposition of static friction, and the force feedback signal is no longer continuous; in the second stage, after the change of movement direction is completed, the hydraulic cylinder piston rod begins to reciprocate in the cylinder body. After the initial few reciprocating motions, a layer of oil film is formed between the hydraulic cylinder piston rod and the cylinder body, and the two are in a state of complete lubrication. In this stage, the friction between the hydraulic cylinder piston rod and the cylinder body is viscous friction, and the magnitude of the friction is related to the movement speed. The force feedback signal of the hydraulic cylinder will be greater than the theoretical value after the viscous friction is superimposed; therefore, if the force feedback signal of the hydraulic cylinder is directly used to calculate the stiffness value of the tested coil spring group, its value is 3.2MN / m, which is twice the theoretical value.

[0053] S3. Design a bandpass filter according to the loading frequency, and use the bandpass filter to perform bandpass filtering on the force feedback signal of the hydraulic cylinder to obtain a force feedback signal after bandpass filtering.

[0054] Specifically, step S3 specifically includes S31-S32:

[0055] S31, obtaining the lower cutoff frequency and the upper cutoff frequency of the loading frequency, setting the filter order and selecting the filter type as a bandpass filter, and calculating the transfer function numerator coefficient and the transfer function denominator coefficient of the bandpass filter, that is:

[0056] [b,a]=butter(N,f min ,f max ,′bandpass′)

[0057] Where b represents the numerator coefficient of the transfer function of the bandpass filter, a represents the denominator coefficient of the transfer function of the bandpass filter, butter represents the filter design function, N represents the filter order, and f min Indicates the lower cutoff frequency of the loading frequency, f max It indicates the upper cutoff frequency of the loading frequency, and bandpass indicates the type of filter.

[0058] S32, according to the transfer function numerator coefficient and the transfer function denominator coefficient of the bandpass filter, the force feedback signal of the hydraulic cylinder is bandpass filtered by using the bandpass filter to obtain the force feedback signal after bandpass filtering, that is:

[0059] F band =filter(b,a,F ori )

[0060] Among them, F band represents the force feedback signal after bandpass filtering, fikter represents the filter function, F ori Represents the force feedback signal of the hydraulic cylinder.

[0061] In this embodiment, the force feedback signal of the hydraulic cylinder is mixed with a lot of noise signals, so the force feedback is firstly subjected to bandpass filtering, such as Fig. 9 As shown, Fig. 9 The force feedback signal after traditional bandpass filtering is shown; since traditional bandpass filtering will remove most of the noise signals in the signal, although the signal curve will become smoother, it still cannot eliminate the influence of the friction of the hydraulic cylinder. The amplitude of the force signal after bandpass filtering is still greater than the theoretical value. This is because the friction of the hydraulic cylinder is caused by the reciprocating motion of the hydraulic cylinder, so the frequency of the friction force is consistent with the movement frequency of the hydraulic cylinder, so the traditional bandpass filtering can never eliminate the influence of friction. And if the force feedback signal after traditional bandpass filtering is used to calculate the stiffness value of the tested coil spring group, its value is 2.5MN / m, which is 1.6 times the theoretical value.

[0062] In summary, in order to obtain accurate test results, it is necessary to further analyze and eliminate the influence of friction from the force feedback signal of the hydraulic cylinder to restore the actual force condition of the test piece.

[0063] S4. With the actual displacement of the test specimen as the abscissa and the force feedback signal after band-pass filtering as the ordinate, draw the load-displacement hysteresis curve after band-pass filtering.

[0064] In this embodiment, the following analysis process is performed to eliminate the friction force, so as to obtain the real load of the hydraulic cylinder acting on the test sample, that is, the reconstructed force feedback signal of the hydraulic cylinder. The specific analysis is as follows:

[0065] First, the actual displacement of the test system is used as the horizontal coordinate, and the theoretical load value of the test sample is used as the vertical coordinate to draw the theoretical load displacement hysteresis curve. That is, the spiral spring group is still used as the test sample for the test, and the actual displacement of the test system is used as the horizontal coordinate, and the theoretical value of the spiral spring group load is used as the vertical coordinate to draw the relationship curve between the two. The relationship curve is: Fig.10 The theoretical load-displacement hysteresis curve in is a straight line segment with the endpoints of point E and point F, because the stiffness of the coil spring group has good linearity.

[0066] Secondly, the force sensor of the hydraulic cylinder is used to collect the force feedback signal of the hydraulic cylinder, and the actual displacement of the test system is used as the horizontal coordinate, and the force feedback signal of the hydraulic cylinder is used as the vertical coordinate to draw the actual load displacement hysteresis curve. That is, the spiral spring group is still used as the test sample for the test, and the actual displacement of the test system is used as the horizontal coordinate, and the actual feedback force signal of the hydraulic cylinder is used as the vertical coordinate to draw the relationship curve between the two. The relationship curve is as follows: Fig.10 The actual load-displacement hysteresis curve in the figure; due to the influence of the friction force of the hydraulic cylinder, the two-dimensional curve between the actual displacement and the actual force feedback signal is a rhombus, and the four endpoints of the rhombus are recorded as A, B, C, and D, which correspond to the moments when the motion acceleration is the largest; at the same time, due to the interference of noise, the actual force feedback signal curve is not smooth; among them, the line segment AB shows a steep drop in the force signal, and the line segment CD shows a steep increase in the force signal, which is caused by the static friction force of the hydraulic cylinder; among them, the line segments BC and DA correspond to the reciprocating motion of the hydraulic cylinder piston rod in the cylinder body. After the initial several reciprocating motions, a layer of oil film is formed between the hydraulic cylinder piston rod and the cylinder body, and the two are in a state of complete lubrication. At this stage, the friction between the piston rod and the cylinder body is viscous friction, and the magnitude of the friction force is related to the motion speed; that is, the force feedback signal of the hydraulic cylinder is superimposed with the system friction, so the amplitude of the force signal is greater than the theoretical value.

[0067] Therefore, based on the analysis of the above theoretical load-displacement hysteresis curve and the actual load-displacement hysteresis curve, it is proposed to draw the load-displacement hysteresis curve after bandpass filtering in order to reconstruct the force feedback signal of the hydraulic cylinder and eliminate the influence of friction. The specific operation process is: the coil spring group is still used as the test sample for the test, the actual displacement of the test system is used as the horizontal coordinate, and the force feedback signal after bandpass filtering is used as the vertical coordinate, and the relationship curve between the two is drawn. The relationship curve is: Fig.10 The load-displacement hysteresis curve after band-pass filtering in the figure. Since band-pass filtering has the effect of data smoothing, the relationship curve between the force feedback signal after band-pass filtering and the actual displacement changes from the original sharp diamond ABCD to a smooth ellipse. In addition, since the traditional band-pass filtering method cannot completely eliminate the influence of friction, the maximum value of the force signal on the ellipse is still greater than the theoretical value.

[0068] S5. Obtain the maximum displacement point on the load-displacement hysteresis curve after bandpass filtering to obtain the maximum true load of the hydraulic cylinder acting on the test sample.

[0069] In this embodiment, from Fig.10 It can also be known that the line segment EF formed by the theoretical load-displacement hysteresis curve of the coil spring group is exactly the chord length of the ellipse formed by the load-displacement hysteresis curve after band-pass filtering. The horizontal coordinates of the two endpoints of the chord length correspond to the maximum value of the actual displacement, and the vertical coordinates of the two endpoints of the chord length correspond to the maximum value of the real load borne by the test piece. The reason is: since the movement speed corresponding to the maximum displacement moment is zero, the friction force of the hydraulic cylinder is also zero when the movement speed is zero; therefore, the maximum real load of the hydraulic cylinder acting on the test piece can be obtained by the maximum displacement point on the load-displacement hysteresis curve after band-pass filtering.

[0070] S6. According to the maximum true load and loading frequency of the hydraulic cylinder acting on the test sample, the load time history of the hydraulic cylinder actually acting on the test sample is reconstructed to obtain a reconstructed force feedback signal of the hydraulic cylinder.

[0071] Specifically, the force feedback signal of the hydraulic cylinder reconstructed in step S6 is:

[0072] F r =A m ·sin(2·π·f·t)

[0073] Among them, F r represents the reconstructed hydraulic cylinder force feedback signal, A m represents the maximum load of the hydraulic cylinder on the test specimen, sin represents the sine function, f represents the loading frequency, and t represents the loading time.

[0074] In this embodiment, a comparison between the force feedback signal of the hydraulic cylinder obtained after reconstruction and the theoretical force value of the test sample is shown in Figure 11, from which it can be seen that the two completely overlap. Therefore, through the method for reconstructing the force feedback signal of the hydraulic cylinder proposed in the present invention, the influence of the friction force of the hydraulic cylinder on the force feedback signal can be eliminated, and the real load of the hydraulic cylinder on the test sample can be obtained, thereby improving the test accuracy.

[0075] In summary, the hydraulic cylinder force feedback signal reconstruction method proposed in the present invention eliminates the influence of the hydraulic cylinder friction on the force feedback signal, and quickly and accurately restores the actual load loaded by the hydraulic cylinder on the test sample, greatly improving the reliability of the test results; at the same time, this force signal reconstruction process is simple and convenient, easy to program, and can be quickly transplanted into the test data processing program for data processing.

[0076] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

[0077] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the present invention.

Claims

1. A method for reconstructing a force feedback signal of a hydraulic cylinder, characterized in that: The following steps are involved: S1. Use the displacement sensor of the hydraulic cylinder to collect the actual displacement of the test sample, and calculate the theoretical load value of the test sample in combination with the theoretical stiffness of the test sample; S2, using the force sensor of the hydraulic cylinder to collect the force feedback signal of the hydraulic cylinder; Among them, the force feedback signal of the hydraulic cylinder includes the friction force of the hydraulic cylinder itself and the real load of the hydraulic cylinder acting on the test sample; S3, designing a bandpass filter according to the loading frequency, and using the bandpass filter to perform bandpass filtering on the force feedback signal of the hydraulic cylinder to obtain a force feedback signal after bandpass filtering; S4. Using the actual displacement of the test sample as the abscissa and the force feedback signal after bandpass filtering as the ordinate, draw a load-displacement hysteresis curve after bandpass filtering; S5, obtaining the maximum displacement point on the load-displacement hysteresis curve after bandpass filtering, and obtaining the maximum true load of the hydraulic cylinder acting on the test sample; S6. According to the maximum true load and loading frequency of the hydraulic cylinder acting on the test sample, the load time history of the hydraulic cylinder actually acting on the test sample is reconstructed to obtain a reconstructed force feedback signal of the hydraulic cylinder.

2. The hydraulic cylinder force feedback signal reconstruction method according to claim 1, characterized in that: The calculation formula of the theoretical load value of the test sample in step S1 is: F t =K t ·Δx Among them, F t Indicates the theoretical load value of the test specimen, K t represents the theoretical stiffness of the test specimen, and Δx represents the actual displacement of the test specimen.

3. The hydraulic cylinder force feedback signal reconstruction method according to claim 2, characterized in that: Step S3 specifically includes: S31, obtaining the lower cutoff frequency and the upper cutoff frequency of the loading frequency, setting the filter order and selecting the filter type as a bandpass filter, and calculating the transfer function numerator coefficient and the transfer function denominator coefficient of the bandpass filter; S32. Performing bandpass filtering on the force feedback signal of the hydraulic cylinder using the bandpass filter according to the numerator coefficient and the denominator coefficient of the transfer function of the bandpass filter to obtain a force feedback signal after bandpass filtering.

4. The hydraulic cylinder force feedback signal reconstruction method according to claim 3, characterized in that: The calculation formula of the transfer function numerator coefficient and the transfer function denominator coefficient of the bandpass filter in step S31 is: [b,a]=butter(N,f min ,f max ,′bandpass′) Where b represents the numerator coefficient of the transfer function of the bandpass filter, a represents the denominator coefficient of the transfer function of the bandpass filter, butter represents the filter design function, N represents the filter order, and f min Indicates the lower cutoff frequency of the loading frequency, f max It indicates the upper cutoff frequency of the loading frequency, and bandpass indicates the type of filter.

5. The hydraulic cylinder force feedback signal reconstruction method according to claim 4, characterized in that: The force feedback signal after bandpass filtering in step S32 is: F band =filter(b,a,F ori ) Among them, F band represents the force feedback signal after bandpass filtering, filter represents the filter function, F ori Represents the force feedback signal of the hydraulic cylinder.

6. The hydraulic cylinder force feedback signal reconstruction method according to claim 5, characterized in that: The force feedback signal of the hydraulic cylinder reconstructed in step S6 is: F r =A m sin(2πft) Among them, F r represents the reconstructed hydraulic cylinder force feedback signal, A m represents the maximum load of the hydraulic cylinder on the test specimen, sin represents the sine function, f represents the loading frequency, and t represents the loading time.

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