High-frequency static pressure supporting oil cylinder and control method thereof

Abstract

The invention discloses a high-frequency static pressure supporting oil cylinder which comprises a front cover and a rear cover, a cylinder barrel is arranged between the front cover and the rear cover, a piston rod is movably arranged in the cylinder barrel, the piston rod partially extends out of the front cover, the high-frequency static pressure supporting oil cylinder further comprises at least two oil cavities, and the at least two oil cavities are formed in the inner circumferential face of the front cover at intervals; at least two oil inlet pipes; a high-frequency servo valve; a capillary throttling device; at least two oil pressure sensors; and at least two high-precision eddy current displacement sensors. According to the high-frequency static pressure supporting oil cylinder, the high-frequency servo valve, the high-precision eddy current displacement sensor and the oil pressure sensor are integrated, and the oil film thickness active adjusting response time is smaller than or equal to 10 ms. The oil cylinder can bear high lateral load, the oil film thickness error is smaller than or equal to 5%, the friction coefficient is reduced to be 30% or below that of a traditional oil cylinder, localization substitution verification is completed, and the requirements for the oil cylinder in the fields of high-precision machine tools, automobile testing and the like are met.

Description

Technical Field

[0001] This application relates to the field of hydrostatic support cylinder technology, and in particular to a high-frequency hydrostatic support cylinder and its control method. Background Technology

[0002] Hydrostatic bearing cylinders are revolutionary hydraulic actuators. They overturn the traditional working principle of hydraulic cylinders, which relies on metal-to-metal contact and sliding friction, and instead adopt hydrostatic bearing technology. At its core, high-pressure oil is continuously injected through an external pump station between the moving piston rod / piston and the fixed cylinder / end cap, forming an extremely thin but highly pressurized oil film that suspends the piston rod, achieving near-zero friction and zero-wear linear motion with pure liquid lubrication.

[0003] In high-precision machine tools, the structure undergoes micro-deformation during high-speed movement or cutting forces. If these micro-deformations are not corrected in a timely manner, thermal and force-induced errors will occur, affecting the accuracy of the high-precision machine tool.

[0004] Therefore, it is necessary to propose a high-frequency hydrostatic support cylinder and its control method, which adjusts the oil film pressure at high frequency to correct the micro-deformation caused by thermal stress or load. This has become an important technical problem that urgently needs to be solved. Summary of the Invention

[0005] This application provides a high-frequency hydrostatic support cylinder and its control method, aiming to solve the problem that in the prior art, machine tools will undergo micro-deformation when moving at high speed or under cutting force. If the micro-deformation cannot be corrected in time, it will lead to thermal and force-induced errors in high-precision machine tools, affecting their accuracy.

[0006] To achieve the above objectives, this application proposes a high-frequency hydrostatic support cylinder, including a front cover and a rear cover, with a cylinder barrel disposed between the front and rear covers. A piston rod is movably disposed within the cylinder barrel, with the piston rod extending out of the front cover. The cylinder also includes: at least two oil chambers, with at least two oil chambers spaced apart on the inner circumferential surface of the front cover; at least two oil inlet pipes, with at least two oil inlet pipes spaced apart along the circumferential direction on the front cover, each oil inlet pipe corresponding to one of the oil chambers; a high-frequency servo valve, with one end of each oil inlet pipe connected to the high-frequency servo valve; a capillary flowmeter, with the other end of each oil inlet pipe connected to the capillary flowmeter, which is connected to a corresponding oil chamber; at least two oil pressure sensors, with at least two oil pressure sensors spaced apart along the circumferential direction on the front cover; and at least two high-precision eddy current displacement sensors, with at least two high-precision eddy current displacement sensors spaced apart along the circumferential direction on the front cover.

[0007] In some embodiments, the capillary flow meter includes: an upper end plate connected to an oil inlet pipe; a body connected to the upper end plate; a capillary tube disposed within the body; fixed blocks disposed at both ends of the body, and the two ends of the capillary tube respectively connected to the fixed blocks; and a lower end plate connected to the body and connected to an oil cavity.

[0008] In some embodiments, the piston rod is further provided with a polytetrafluoroethylene coating.

[0009] Based on another objective of the present invention, the present invention provides the following technical solution: a control method for a high-frequency hydrostatic support cylinder, wherein the control method uses a high-frequency hydrostatic support cylinder as described above, and the control method specifically includes the following steps: S1, obtaining the target pressure of at least two oil chambers; S2, obtaining the actual pressure of at least two oil chambers through an oil pressure sensor; S3, obtaining the pressure error based on the target pressure and the actual pressure; S4, calculating the control quantity based on the pressure error; S5, controlling the high-frequency servo valve through the control quantity, the high-frequency servo valve adjusting its opening according to the control quantity, thereby controlling the flow rate entering the oil chamber, changing the pressure of each oil chamber, and adjusting the oil film thickness.

[0010] In some embodiments, the pressure error in S3 above is calculated as follows:

[0011] In the formula: For the pressure error of each oil chamber, The target pressure for each oil chamber. This represents the actual pressure in each oil chamber.

[0012] In some embodiments, the calculation method for the control quantity in S4 above is as follows:

[0013] In the formula: To control the quantity, For PID parameters, To control the cycle, This is the gain coefficient.

[0014] In some embodiments, the method for obtaining the target pressure in S1 above is specifically as follows: S11. Obtain the oil film thickness of at least two oil chambers using a high-precision eddy current displacement sensor; S12. Calculate the attitude error based on the oil film thickness of at least two oil chambers; S13. Obtain the correction force based on the attitude error; S14. Distribute the correction force to at least two oil chambers and obtain the target pressure of at least two oil chambers.

[0015] In some embodiments, the attitude error in S12 above is calculated as follows:

[0016] In the formula: , , , These represent the oil film thicknesses in the four oil chambers, This represents the attitude error in one direction. This represents the attitude error in another direction.

[0017] In some embodiments, the method for calculating the corrective force in S13 above is as follows:

[0018] In the formula: This represents the corrective force in one direction. This represents the corrective force in another direction. For PID parameters, These are PID parameters.

[0019] In some embodiments, the target pressure calculation method for at least two oil chambers in S14 above is as follows:

[0020] In the formula: As the reference pressure, The effective area of ​​each oil cavity.

[0021] This application proposes a high-frequency hydrostatic support cylinder, including a front cover and a rear cover, with a cylinder barrel disposed between the front and rear covers. A piston rod is movably disposed within the cylinder barrel, with the piston rod extending out of the front cover. The cylinder also includes: at least two oil chambers, with at least two oil chambers spaced apart on the inner circumferential surface of the front cover; at least two oil inlet pipes, with at least two oil inlet pipes spaced apart along the circumferential direction on the front cover, each oil inlet pipe corresponding to one of the oil chambers; a high-frequency servo valve, with one end of each oil inlet pipe connected to the high-frequency servo valve; a capillary flowmeter, with the other end of each oil inlet pipe connected to the capillary flowmeter, which is connected to a corresponding oil chamber; at least two oil pressure sensors, with at least two oil pressure sensors spaced apart along the circumferential direction on the front cover; and at least two high-precision eddy current displacement sensors, with at least two high-precision eddy current displacement sensors spaced apart along the circumferential direction on the front cover. The high-frequency hydrostatic support cylinder provided by this application integrates a high-frequency servo valve, high-precision eddy current displacement sensors, and oil pressure sensors, achieving an active oil film thickness adjustment response time ≤10ms. It can withstand high lateral loads, with an oil film thickness error of ≤5% and a friction coefficient reduced to less than 30% of that of traditional hydraulic cylinders. It has completed the verification of domestic substitution and meets the needs of hydraulic cylinders in fields such as high-precision machine tools and automotive testing. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein: Figure 1 This is a three-dimensional structural diagram of a high-frequency hydrostatic support cylinder according to an embodiment of this application; Figure 2 for Figure 1 Enlarged view of part A in the middle; Figure 3 This is a front view of a high-frequency hydrostatic support cylinder according to an embodiment of this application; Figure 4 for Figure 3 Sectional view at point BB; Figure 5 for Figure 4 Enlarged view of a section in the middle C; Figure 6 This is a schematic diagram of the capillary infiltrator in one embodiment of this application.

[0023] In the diagram: 1. Rear cover; 2. Servo oil supply valve; 3. Cylinder; 4. Piston rod; 5. Load; 6. Front cover; 7. High-frequency servo valve; 8. High-precision eddy current displacement sensor; 9. Oil pressure sensor; 10. Magnetostrictive sensor; 11. Oil inlet pipe; 12. Sealing gasket; 13. Capillary flowmeter; 131. Body; 132. Upper end plate; 133. Fixing block; 134. Capillary tube; 135. Lower end plate; 136. Oil chamber. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0025] Example 1 See Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5As shown, this application discloses a high-frequency hydrostatic support cylinder, including a front cover 6 and a rear cover 1. A cylinder 3 is disposed between the front cover 6 and the rear cover 1. A piston rod 4 is movably disposed inside the cylinder 3, with a portion of the piston rod 4 extending out of the front cover 6. The cylinder also includes: at least two oil chambers 14, with at least two oil chambers 14 spaced apart on the inner circumferential surface of the front cover 6; at least two oil inlet pipes 11, with at least two oil inlet pipes 11 spaced apart along the circumferential direction on the front cover 6, and the at least two oil inlet pipes 11 correspondingly connected to the oil chambers 14; a high-frequency servo valve 7, with one end of the oil inlet pipe 11 connected to the high-frequency servo valve 7; a capillary flowmeter 13, with the other end of the oil inlet pipe 11 connected to the capillary flowmeter 13, and the capillary flowmeter 13 connected to the corresponding oil chamber 14; at least two oil pressure sensors 9, with at least two oil pressure sensors 9 spaced apart along the circumferential direction on the front cover 6; and at least two high-precision eddy current displacement sensors 8, with at least two high-precision eddy current displacement sensors 8 spaced apart along the circumferential direction on the front cover 6.

[0026] The front cover 6, rear cover 1, piston rod 4, and cylinder 3 constitute the main structure of the high-frequency hydrostatic support cylinder. Other structures on the high-frequency hydrostatic support cylinder are directly or indirectly installed on the main structure. A servo oil supply valve 2 is also provided on the rear cover 1, and the load 5 is provided at the end of the piston rod 4 away from the load 5.

[0027] It can be understood that this also includes a hydraulic station, used to supply oil to multiple high-frequency servo valves 7 and servo oil supply valves 2. A magnetostrictive sensor 10 is also installed inside the rear cover 1 to detect the stroke of the piston rod 4. The magnetostrictive sensor 10 and the servo oil supply valve 2 form a closed-loop stroke control, effectively improving the stroke accuracy of the piston rod 4. The high-frequency servo valves 7 are selected from the MOOGD661 series, ATOS DLHZO-TE-040-L31 40 series, or MTS 257 servo valves. The frequency response of the aforementioned high-frequency servo valves 7 is ≥200Hz. The oil pressure sensor 9 is a Honeywell MIP series high-performance miniature pressure sensor. Since the hydraulic station, magnetostrictive sensor 10, oil pressure sensor 9, servo oil supply valve 2, and high-frequency servo valve 7 are all mature existing technologies, no restrictions are placed on the specific structures of the hydraulic station, magnetostrictive sensor 10, oil pressure sensor 9, servo oil supply valve 2, and high-frequency servo valve 7.

[0028] Among them, at least two oil chambers 14 include four rectangular oil chambers 14, which are evenly spaced, that is, the included angle between any two adjacent oil chambers 14 is 90°. Figure 2 As shown, there are two oil chambers 14, 1 and 3, in the x-direction, and two oil chambers 14, 2 and 4, in the y-direction. The oil supplied by the hydraulic station enters the corresponding oil chamber 14 through the high-frequency servo valve 7, the oil inlet pipe 11, and the capillary flow meter 13. The high-frequency servo valve 7 can adjust the oil supply pressure, thereby adjusting the pressure inside the oil chamber 14 to adjust the oil film thickness and achieve the correction of the piston rod 4.

[0029] In this embodiment, a sealing gasket 12 is also provided between the oil inlet pipe 11 and the front cover 6, which effectively improves the sealing ability between the oil inlet pipe 11 and the front cover 6 and prevents oil leakage.

[0030] The high-frequency servo valve 7, high-precision eddy current displacement sensor 8, and oil pressure sensor 9 constitute the active oil film thickness adjustment structure. The high-precision eddy current displacement sensor 8 monitors the oil film thickness. When an abnormality occurs in the oil film thickness, a correction pressure is generated based on the thickness. The high-frequency servo valve 7 then adjusts the pressure in each oil chamber 14 to the preset correction pressure to correct the deflection of the piston rod 4. Upon receiving the correction pressure, the high-frequency servo valve 7 can quickly adjust its output pressure, thereby adjusting the pressure inside the oil chamber 14 to the preset pressure.

[0031] The capillary microfluidic device 13 forms a feedback adjustment structure for the oil film thickness. When the piston rod 4 deflects, it squeezes the corresponding oil chamber 14. The oil in the oil chamber 14 is squeezed and immediately generates a hydraulic restoring force, preventing the piston rod 4 from deviating rapidly. This feedback adjustment structure buys valuable time for the response of the active adjustment structure, avoiding cylinder runaway. Furthermore, the hydraulic resistance provided by the capillary microfluidic device 13 can effectively improve the stiffness of the oil film, enabling the cylinder to withstand high lateral loads, preferably 5-8 times the shear force of a conventional cylinder.

[0032] Specifically, the high-frequency hydrostatic support cylinder provided in this application integrates a high-frequency servo valve 7, a high-precision eddy current displacement sensor 8, and an oil pressure sensor 9, with an active oil film thickness adjustment response time ≤10ms. It can withstand high lateral loads, with an oil film thickness error ≤5%, and the friction coefficient is reduced to less than 30% of that of traditional cylinders. It completes the verification of domestic substitution and meets the cylinder requirements of high-precision machine tools, automotive testing, and other fields.

[0033] See Figure 6As shown, in some embodiments, the capillary flow meter 13 includes: an upper end plate 132 connected to an oil inlet pipe 11; an oil inlet chamber provided inside the upper end plate 132; a body 131 connected to the upper end plate 132; a capillary tube 134 disposed inside the body 131; a fixing block 133 provided at both ends of the body 131, and the two ends of the capillary tube 134 respectively connected to the fixing block 133; the fixing block 133 is snapped or welded to the body 131, and the capillary tube 134 is connected to the fixing block 133 and the body 131 by precision pressing, and through holes adapted to the capillary tube 134 are provided on the fixing block 133 and the body 131; and a lower end plate 135 connected to the body 131 and connected to an oil chamber 14. The lower end plate 135 is provided with an oil outlet cavity and an oil outlet. The oil outlet is connected to the oil outlet cavity. One end of the capillary tube 134 is connected to the oil inlet cavity, and the other end of the capillary tube 134 is connected to the oil outlet cavity.

[0034] It is understood that the capillary tubes 134 are preferably 4 to 12, more preferably 8. Sealing rings are provided between the capillary tubes 134 and the fixing block 133, between the fixing block 133 and the upper end plate 132, and between the fixing block 133 and the lower end plate 135 to ensure their sealing performance and prevent oil leakage. The body 131 is connected to the inner circumferential surface of the front cover 6 by screwing or snapping.

[0035] The capillary micro-flow element 13 provides hydraulic resistance, enabling the oil film to resist external compression, i.e., oil film stiffness. Higher pressure generally results in greater stiffness, allowing the piston rod 4 to withstand higher lateral forces. The pressure in each oil chamber 14 can be independently controlled via the corresponding capillary micro-flow element 13. When the piston rod 4 deflects, each oil chamber 14 generates a net restoring force, actively pushing the eccentric piston rod 4 back to the center. The damping characteristics of the capillary micro-flow element 13 help filter pressure pulsations in the hydraulic station, prevent pressure oscillations, and make the oil film more stable.

[0036] In some embodiments, the piston rod 4 is further comprising a polytetrafluoroethylene (PTFE) coating. The PTFE coating is applied to the middle section of the piston rod 4, typically using methods such as flame spraying. The PTFE coating has an extremely low coefficient of friction, with a dry coefficient of friction of 0.04-0.07, and is chemically inert, effectively reducing the friction between the piston rod 4 and the front cover 6. Other parts of the piston rod 4 are plasma-sprayed with a tungsten carbide coating to enhance the load-bearing capacity of these other parts.

[0037] Understandably, after the coating is applied, the piston rod 4 still needs to be precision ground and polished to ensure that its dimensions and surface meet design requirements. The double-sided clearance between the piston rod 4 and the front cover 6 is 0.020±0.004mm. Through the aforementioned PTFE coating and clearance settings, leakage can be reduced to below 0.1L / min without using traditional sealing rings.

[0038] The cylinder barrel 3 is made of 42CrMoA alloy steel, heat-treated to a hardness of HRC28-32, with a tensile strength ≥850MPa. The front cover 6 and rear cover 1 are made of 45# steel and are connected by screws and lock nuts. The cylinder barrel 3 is snapped between the front cover 6 and rear cover 1. Sealing rings are installed between the front cover 6 and rear cover 1 and the cylinder barrel 3 to ensure sealing performance. The piston rod 4 is made of 38CrMoAlA nitrided steel.

[0039] Example 2 In this embodiment, the parts that are the same as in Embodiment 1 are given the same reference numerals, and the same text descriptions are omitted.

[0040] This embodiment discloses a control method for a high-frequency hydrostatic support cylinder. The control method uses a high-frequency hydrostatic support cylinder as described in Embodiment 1. The controller is an FPGA or an FPGA + real-time microcontroller. The above control method is developed based on LabVIEW. It should be noted that the following embodiments are described using at least two oil chambers as examples. That is, those skilled in the art will understand that when the number of oil chambers is more than two, the purpose of this invention can be achieved through adapted control logic (such as controlling only the attitude error in a single direction). The following description using at least two examples should not be construed as limiting the scope of protection of this invention.

[0041] The specific control method includes the following steps: S1. Obtain the target pressure of at least two oil chambers; S2. Obtain the actual pressure of at least two oil chambers through oil pressure sensors; the controller's control cycle is 1ms, and data acquisition and calculation are performed once per control cycle. S3. Obtain the pressure error based on the target pressure and actual pressure; S4. Calculate the control quantity based on the pressure error; S5. Control the high-frequency servo valve through the control quantity. The high-frequency servo valve adjusts its opening according to the control quantity, thereby controlling the flow rate into the oil chambers and changing the pressure of each oil chamber to adjust the oil film thickness. The control method adopts incremental PID calculation with feedforward, perfectly integrating predictability and anti-saturation, achieving a response speed close to the physical limit while ensuring control stability. The incremental algorithm, by outputting changes rather than absolute values, naturally avoids integral saturation, keeping the system stable under frequent large-value commands; while the feedforward control performs pre-action based on the changing trend of the target command, directly offsetting the inertial delay of the controlled object and minimizing the phase lag of pressure establishment. The combination of the two allows the pressure loop to track rapidly changing pressure commands without overshoot at the microsecond level, achieving high-frequency response of the system and strong robustness.

[0042] In some embodiments, the pressure error in S3 above is calculated as follows:

[0043] In the formula: For the pressure error of each oil chamber, The target pressure for each oil chamber. This represents the actual pressure in each oil chamber.

[0044] In some embodiments, the calculation method for the control quantity in S4 above is as follows:

[0045] In the formula: To control the quantity, For PID parameters, To control the cycle, This is the gain coefficient. The controller will calculate the digital control quantity. The data is written to the data register of the designated channel in the AO module. The DAC circuit converts this digital value into the corresponding analog voltage in real time. The analog voltage is fed into a voltage-to-current converter integrated into the high-frequency servo valve driver. This amplifier linearly converts the voltage signal into a proportional current and has current negative feedback to ensure that the output current accurately follows the input voltage, unaffected by coil resistance temperature drift. The proportional current flows through the coil of the high-frequency servo valve torque motor, generating an electromagnetic force proportional to the current. This electromagnetic force drives the valve core of the high-frequency servo valve to overcome spring force and hydraulic force, generating a displacement proportional to the proportional current. The valve core displacement changes the flow area of ​​the throttling window, thereby precisely controlling the flow rate and pressure to the hydraulic cylinder oil chamber, ultimately achieving regulation of the oil film pressure.

[0046] In some embodiments, the method for obtaining the target pressure in S1 above is specifically as follows: S11. Obtain the oil film thickness of at least two oil chambers using a high-precision eddy current displacement sensor; S12. Calculate the attitude error based on the oil film thickness of at least two oil chambers; S13. Obtain the correction force based on the attitude error; S14. Distribute the correction force to at least two oil chambers and obtain the target pressure of at least two oil chambers.

[0047] In some embodiments, the attitude error in S12 above is calculated as follows:

[0048] In the formula: , , , These represent the oil film thicknesses in the four oil chambers, This represents the attitude error in one direction. This represents the attitude error in another direction.

[0049] In some embodiments, the method for calculating the corrective force in S13 above is as follows:

[0050] In the formula: This represents the corrective force in one direction. This represents the corrective force in another direction. For PID parameters, These are PID parameters.

[0051] In some embodiments, the target pressure calculation method for at least two oil chambers in S14 above is as follows:

[0052] In the formula: As the reference pressure, The effective area of ​​each oil chamber. The reference pressure is usually selected between 30% and 70% of the supply pressure.

[0053] This application combines a high-frequency servo valve 7, a capillary microflow element 13, and multi-sensor closed-loop control. The high-frequency servo valve 7 provides high-speed active response capability, the capillary microflow element 13 provides transient passive damping and high stiffness, and the multi-sensor closed-loop control ensures precise control objectives. The synergistic effect of these three components produces a synergistic effect of '1+1+1>3', making the response time (≤10ms) and accuracy (error ≤5%) of active oil film thickness adjustment far exceed those of existing static load support cylinders.

[0054] Specifically, during the test, a step position command with an amplitude of 10μm was sent, and the time required for the pressure in oil chamber 14 to reach 95% of the target value and the time required for the displacement of piston rod 4 to reach 95% of the target value were recorded. The results showed that the step response time of the pressure ring in oil chamber 14 was 2.8ms; the overall system position step response time was 8.5ms. When piston rod 4 was in sinusoidal reciprocating motion at 1m / s at 50Hz, the oil film thickness between piston rod 4 and the bearing surface was monitored in real time using a high-precision eddy current sensor, and the percentage error between the oil film thickness and the target thickness (25μm) was calculated. The results showed that during full-stroke dynamic operation, the oil film thickness fluctuated between 24.1μm and 25.8μm, with a maximum dynamic error of ±3.4%. In both static and dynamic states of piston rod 4, radial static loads and alternating loads were applied through a lateral loading device, with load values ​​reaching 5.2 times the rated shear force of a conventional hydraulic cylinder of the same specification. Simultaneously, the oil film thickness and the eccentricity of piston rod 4 were monitored. The results show that under 5.2 times the rated lateral load, the maximum radial eccentricity of piston rod 4 is 1.1 μm, the oil film remains intact, and no metal-to-metal contact occurs. The controller can automatically adjust the pressure difference in oil chamber 14 to stably maintain the alignment of piston rod 4. Under no-load 5, the pressure required to drive piston rod 4 at a constant low speed (5 mm / s) was measured, its equivalent Coulomb friction was calculated, and compared with a cylinder of the same size using a traditional U-shaped seal. The results show that the equivalent dynamic friction coefficient of piston rod 4 is 0.008, while the friction coefficient of the traditional comparison cylinder is 0.035.

[0055] The inventors have discovered that by combining the active response capability provided by the high-frequency servo valve, the passive damping and high stiffness provided by the capillary flowmeter, and the precise target provided by the multi-sensor closed-loop control, a synergistic effect is achieved, resulting in a system response time and control accuracy that are far superior to existing technologies, thus solving the problem that traditional hydraulic cylinders cannot correct deviations in real time.

[0056] The above description is only a part or preferred embodiment of this application. Neither the text nor the drawings should limit the scope of protection of this application. All equivalent structural transformations made using the content of this application's specification and drawings under the overall concept of this application, or direct / indirect applications in other related technical fields, are included within the scope of protection of this application.

Claims

1. A high-frequency hydrostatic support cylinder, comprising a front cover and a rear cover, wherein a cylinder is disposed between the front cover and the rear cover, and a piston rod is movably disposed within the cylinder, the piston rod partially extending out of the front cover, characterized in that, Also includes: At least two oil chambers are provided at intervals on the inner circumferential surface of the front cover; At least two oil inlet pipes are provided on the front cover at circumferential intervals, and the at least two oil inlet pipes are connected to the oil chamber in a one-to-one correspondence; A high-frequency servo valve, with one end of the oil inlet pipe connected to the high-frequency servo valve; A capillary flowmeter, the other end of the oil inlet pipe is connected to the capillary flowmeter, and the capillary flowmeter is connected to the corresponding oil chamber; At least two oil pressure sensors are provided on the front cover at circumferential intervals; At least two high-precision eddy current displacement sensors are provided on the front cover at circumferential intervals.

2. The high-frequency hydrostatic support cylinder according to claim 1, characterized in that, The capillary flowmeter includes: Upper end plate, the upper end plate being connected to the oil inlet pipe; The upper end plate is connected to the main body; Capillary tube, wherein the capillary tube is disposed within the body; The fixing blocks are provided at both ends of the body, and the two ends of the capillary are respectively connected to the fixing blocks; The lower end plate is connected to the body and communicates with the oil cavity.

3. A high-frequency hydrostatic support cylinder according to claim 1, characterized in that, Also includes: A polytetrafluoroethylene (PTFE) coating is provided on the piston rod.

4. A control method for a high-frequency hydrostatic support cylinder, wherein the control method uses a high-frequency hydrostatic support cylinder according to any one of claims 1-3, characterized in that, The control method specifically includes the following steps: S1. Obtain the target pressure of at least two oil chambers; S2. Obtain the actual pressure of at least two oil chambers through oil pressure sensors; S3. Obtain the pressure error based on the target pressure and the actual pressure; S4. Calculate the control quantity based on the pressure error; S5. The high-frequency servo valve is controlled by the control quantity. The high-frequency servo valve adjusts its opening according to the control quantity, thereby controlling the flow rate into the oil chamber and changing the pressure of each oil chamber to adjust the oil film thickness.

5. The high-frequency hydrostatic support cylinder and its control method according to claim 4, characterized in that, The method for calculating the pressure error in S3 above is as follows: ； In the formula: For the pressure error of each oil chamber, The target pressure for each oil chamber. This represents the actual pressure in each oil chamber.

6. The high-frequency hydrostatic support cylinder and its control method according to claim 5, characterized in that, The calculation method for the control quantity in S4 above is as follows: ； In the formula: To control the quantity, For PID parameters, To control the cycle, This is the gain coefficient.

7. The high-frequency hydrostatic support cylinder and its control method according to claim 4, characterized in that, The specific method for obtaining the target pressure in S1 above is as follows: S11. Obtain the oil film thickness of at least two oil chambers using a high-precision eddy current displacement sensor; S12. Calculate the attitude error based on the oil film thickness of at least two oil chambers; S13. Obtain the correction force based on the attitude error; S14. Distribute the correction force to at least two oil chambers and obtain the target pressure of at least two oil chambers.

8. The high-frequency hydrostatic support cylinder and its control method according to claim 7, characterized in that, The method for calculating the attitude error in S12 above is as follows: ； In the formula: , , , These represent the oil film thicknesses in the four oil chambers, This represents the attitude error in one direction. This represents the attitude error in another direction.

9. A high-frequency hydrostatic support cylinder and its control method according to claim 8, characterized in that, The calculation method for the corrective force in S13 above is as follows: ； In the formula: This represents the corrective force in one direction. This represents the corrective force in another direction. For PID parameters, These are PID parameters.

10. A high-frequency hydrostatic support cylinder and its control method according to claim 7, characterized in that, The method for calculating the target pressure of at least two oil chambers in S14 above is as follows: ； In the formula: As the reference pressure, The effective area of ​​each oil cavity.

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