A magnetorheological buffer for aircraft landing gear and control method thereof

Abstract

The present invention provides a magnetorheological damper and control method for aircraft landing gear. The magnetorheological damper includes a magnetorheological valve having two excitation coils wound in opposite directions. The generated magnetic circuit is perpendicular to the oil damping channel and overlaps with each other between the two coil slots, so that the entire damping channel is covered with a magnetic field. The magnetorheological damper also includes a working cylinder, a piston rod, a guide, an actuating piston, a floating piston, and a connecting rod. The working cylinder has an oil chamber and an air chamber. The magnetorheological valve is fixed in the oil chamber by a connecting rod. The floating piston sleeved on the connecting rod can isolate the magnetorheological fluid from the air in the air chamber. The present invention constructs different neural network models to reliably predict the damper input current curve under different drop shock conditions, and presets them in an external power supply controller to control the magnitude of the damper input current, thereby achieving adaptive damping adjustment of the magnetorheological damper, ensuring a constant output force of the magnetorheological damper and improving the buffering efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of large-scale structural impact load mitigation control in the field of aerospace, and particularly relates to a magnetorheological buffer for aircraft landing gear and a control method thereof. Background Art

[0002] During landing, aircraft encounter complex external environmental excitations, which can cause severe structural impacts. Therefore, significant attention must be paid to mitigating structural impact loads. Currently, installing buffers in the landing gear is a common practice. However, traditional oil-pneumatic buffers typically adjust the damping force by adjusting the size of the oil needle within the oil chamber. However, since the needle size is fixed and can only be designed based on anticipated landing conditions to meet the buffering efficiency requirements under these conditions, the buffering efficiency is low under adverse landing conditions or landing conditions that cannot be anticipated in advance. Furthermore, the buffering efficiency is difficult to flexibly adjust to different landing scenarios (such as asymmetric landings and landings in adverse weather conditions). Consequently, the system has poor adaptability to complex and changing landing conditions and cannot effectively meet the efficient buffering requirements of modern aircraft.

[0003] Magnetorheological buffers are semi-active control devices that use the magnetorheological effect of magnetorheological fluid under the action of a controllable magnetic field to provide controllable damping. Due to their simple structure and reliable operation, and the ability to adjust the control current in real time according to different application conditions to ensure buffering efficiency, magnetorheological buffers are widely used in impact mitigation in actual engineering.

[0004] Currently, the most common control algorithm used to mitigate the drop load of magnetorheological landing gear is the On-Off control method. This control algorithm controls the power on and off by triggering conditions during the landing gear drop process. That is, the power is disconnected when the output force of the magnetorheological buffer is high, and the power is connected when the output force of the magnetorheological buffer is low. This method can adjust the output force of the magnetorheological buffer within a certain range, but this control method has low control accuracy and cannot achieve precise control of the buffer during the aircraft landing gear drop process. Summary of the Invention

[0005] The purpose of the present invention is to solve the shortcomings of existing magnetorheological dampers and control methods that cannot meet the adaptive damping adjustment control during the landing shock process of aircraft landing gear, and to provide a magnetorheological damper and control method for aircraft landing gear.

[0006] To achieve the above objectives, the technical solutions provided by the present invention are:

[0007] The present invention provides a magnetorheological damper control method, which is implemented based on a magnetorheological damper for aircraft landing gear. The magnetorheological damper for aircraft landing gear includes a working cylinder, a first connector, a cylinder end cover, a piston rod, a guide, an actuating piston, a connecting rod, a floating piston, an inflation nozzle, a second connector, and the aforementioned magnetorheological valve.

[0008] The working cylinder has a working cavity, including an oil cavity and an air cavity that are connected;

[0009] One end of the piston rod is connected to the actuating piston and is located in one end of the oil chamber, and the other end of the piston rod is located outside the working cylinder and is fixedly connected to the first connector;

[0010] The cylinder end cover is coaxially sealed and mounted on one end of the working cylinder, and the guide is nested on the piston rod body and is located between the cylinder end cover and the actuating piston;

[0011] The magnetorheological valve is located at the other end of the oil chamber, and the second end cover of the magnetorheological valve is connected to a second connector coaxially mounted on the other end of the working cylinder barrel through the connecting rod; the connecting rod has a central through hole for allowing the wire to extend out of the working cylinder barrel;

[0012] The oil cavity is filled with magnetorheological fluid, and the amount of the magnetorheological fluid injected must at least cover the magnetorheological valve; the air cavity is filled with gas through the inflation nozzle;

[0013] The floating piston is sleeved on the connecting rod body and can slide along the connecting rod under the action of the gas in the gas cavity to separate the magnetorheological fluid from the gas;

[0014] The first connector is used to connect one end of the magnetorheological buffer to the aircraft landing gear wheel, and the second connector is used to install the other end of the magnetorheological buffer at the connection position between the aircraft landing gear and the aircraft body.

[0015] The control method comprises the following steps:

[0016] Step 1: Obtain the optimal expected damping force under several landing gear drop conditions, construct an expected damping force neural network model, and train the constructed expected damping force neural network model using the drop condition parameters and the corresponding optimal expected damping force as training data;

[0017] The expected damping force neural network model is used to predict the optimal expected damping force corresponding to the output according to the input drop shock working condition parameters;

[0018] The drop condition parameters include drop mass, sinking speed and initial pressure of the buffer;

[0019] Step 2: Construct a current time characteristic neural network model and a current numerical characteristic neural network model, and train and predict the current time characteristic neural network model and the current numerical characteristic neural network model to obtain the time characteristic data and numerical characteristic data of the magnetorheological buffer input current under different drop shock conditions:

[0020] Step 2.1, based on the output force expression of the magnetorheological damper The current time characteristic neural network model and the current numerical characteristic neural network model are constructed respectively, where the formula middle is the output force of the magnetorheological buffer, is the compression of the magnetorheological buffer, is the compression speed of the magnetorheological buffer, Input current to the magnetorheological buffer;

[0021] The current time characteristic neural network model is used to output the corresponding time characteristic of the magnetorheological buffer input current according to the input drop shock working condition parameters and the corresponding optimal expected damping force;

[0022] The current numerical characteristic neural network model is used to output the corresponding numerical characteristics of the magnetorheological buffer input current according to the input drop shock working condition parameters and the corresponding optimal expected damping force;

[0023] Step 2.2, obtaining time characteristic data and numerical characteristic data of the magnetorheological damper input current under several landing gear drop conditions, using the parameters of each drop condition, the corresponding optimal expected damping force predicted and output by the expected damping force neural network model, and the time characteristic or numerical characteristic data of the magnetorheological damper input current as training data, to train the current time characteristic neural network model and the current numerical characteristic neural network model respectively;

[0024] Step 2.3, respectively predicting and outputting the time characteristic data and the numerical characteristic data of the magnetorheological buffer input current corresponding to different drop shock conditions through the current time characteristic neural network model and the current numerical characteristic neural network model;

[0025] Step 3: Fitting the time characteristic data and the numerical characteristic data of the input current of the magnetorheological buffer under the same drop shock working condition obtained in step 2 to obtain the current-time curve of the magnetorheological buffer under the corresponding drop shock working condition;

[0026] Step 4: The current-time curve of the magnetorheological buffer in each drop shock working condition obtained in step 3 is preset in the external power supply controller. The power supply controller controls and adjusts the input current of the magnetorheological buffer according to the preset current-time curve of the magnetorheological buffer, so that the output force of the magnetorheological buffer is equal to the optimal expected damping force of the magnetorheological buffer, thereby realizing adaptive adjustment of the output force of the magnetorheological buffer.

[0027] Furthermore, the magnetorheological valve includes a housing, a first end cover, a second end cover, a first excitation coil, a second excitation coil, an iron core, a wire and a magnetorheological fluid;

[0028] The iron core is coaxially mounted in the cavity of the housing, and a gap exists between the outer wall of the iron core and the inner wall of the housing to form an annular oil damping channel; the iron core has a central hole opened along its axis;

[0029] Two annular coil slots are symmetrically provided on the outer wall of the iron core. A single conductor of the first excitation coil and the second excitation coil is wound in the two annular coil slots. After winding, the free end of the conductor is led out of the iron core through the central hole of the iron core. The winding directions of the first excitation coil and the second excitation coil are opposite.

[0030] The first end cover and the second end cover are coaxially nested at both ends of the housing, and the end surfaces of the first end cover and the second end cover are provided with a plurality of arc-shaped holes around the circumference for the magnetorheological fluid to pass through and enter the annular oil damping channel;

[0031] The second end cover has a central through hole coaxial with the central hole of the iron core, for the wire to pass through and extend out of the shell to connect to an external power source.

[0032] Furthermore, the first excitation coil and the second excitation coil are treated with vacuum paint to improve the insulation strength of the excitation coils.

[0033] Furthermore, the iron core and the shell are made of electrical pure iron material; the first end cover and the second end cover are made of stainless steel material.

[0034] Furthermore, the center hole of the iron core is a multi-step hole, wherein one end of the center hole is a threaded hole for threaded connection with the connecting rod.

[0035] Furthermore, after the connecting rod is connected to the threaded hole and the central through hole of the second end cover of the magnetorheological valve, it is sealed with hot melt adhesive to fix the wire located in the central hole of the iron core.

[0036] Furthermore, it also includes a polyurethane rubber pad, which is located at the end of the cylinder end cover and is coaxially connected to the cylinder end cover to prevent the cylinder end cover from colliding with the first connecting head.

[0037] Furthermore, in step 1, the specific process of obtaining the optimal expected damping force under several landing conditions of the aircraft landing gear is as follows:

[0038] Step 1.1: traverse and obtain the expected damping force for each drop shock working condition, and calculate the buffering efficiency of the magnetorheological buffer corresponding to the expected damping force according to the formula:

[0039] The calculation formula of the buffering efficiency of the magnetorheological buffer is:

[0040]

[0041] Where, The moment when the first compression stroke of the magnetorheological buffer ends; is the maximum output force of the magnetorheological buffer; is the maximum compression amount of the magnetorheological buffer; The output force of the magnetorheological buffer at any time within the first compression stroke, is the compression amount of the magnetorheological buffer at any time within the first compression stroke;

[0042] Step 1.2: traverse all expected damping forces and their corresponding MR damper efficiencies, and take the expected damping force corresponding to the highest MR damper efficiency as the optimal expected damping force under the current drop condition;

[0043] Step 1.3: Obtain the optimal expected damping force corresponding to each drop condition according to the method in step 1.2.

[0044] Furthermore, in step 2.2, time characteristic data and numerical characteristic data of the input current of the magnetorheological buffer under several landing conditions of the aircraft landing gear are obtained based on simulation.

[0045] The advantages of the present invention are:

[0046] 1. The magnetorheological valve of the magnetorheological buffer of the present invention adopts a double-coil reverse winding structure. The two coils generate magnetic circuits in opposite directions. Both magnetic circuits can generate magnetic induction intensity perpendicular to the oil damping channel, and the magnetic induction intensity is superimposed on each other in the middle part of the two coil slots. The entire damping channel is covered with magnetic induction intensity, which effectively solves the problem of low magnetic field utilization efficiency of the magnetorheological valve, realizes efficient utilization of the magnetic induction intensity of the magnetorheological buffer, and increases the damping adjustment range of the magnetorheological buffer.

[0047] 2. Based on the neural network control algorithm, the present invention constructs three neural network models of the designed magnetorheological buffer according to different landing conditions of the aircraft (including the landing mass of the landing gear, the sinking speed and the initial pressure of the buffer). First, the expected damping force neural network model is trained and predicted to obtain the optimal expected damping force under different working conditions. Then, the current time characteristic neural network model and the current numerical characteristic neural network model are trained and predicted respectively with the optimal expected damping force obtained under different landing conditions to obtain the current time characteristic and the current numerical characteristic under the corresponding working conditions. That is, the trained and predicted neural network model can accurately predict the control current time history under different working conditions, and can directly adaptively adjust the magnetorheological buffer current through the constructed neural network model according to different landing conditions, thereby realizing adaptive adjustment of the magnetorheological buffer damping parameters, effectively reducing the magnetorheological buffer output force peak, greatly improving the buffering efficiency of the buffer, and solving the problems of fixed and unadjustable damping parameters of traditional aircraft landing gear buffers and low buffering efficiency of traditional control methods.

[0048] 3. Simulation verification shows that the control method of the present invention is reliable and effective. Compared with traditional magnetorheological buffers and traditional control methods, the output force peak of the magnetorheological buffer is reduced, and the buffering efficiency is as high as over 95%, with significant effects.

[0049] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0051] Figure 1 This is a front view of the magnetorheological valve of the present invention;

[0052] Figure 2 yes Figure 1 AA cross-sectional view of the medium magnetorheological valve;

[0053] Figure 3 is a magnetic field distribution diagram of the magnetorheological valve in the present invention;

[0054] Figure 4 is a three-dimensional schematic diagram of a magnetorheological buffer of the present invention;

[0055] Figure 5 is a cross-sectional view of the magnetorheological buffer of the present invention along its axial direction;

[0056] Figure 6 This is a flow chart of the magnetorheological buffer control method of the present invention;

[0057] Figure 7 It is the landing gear drop dynamics model diagram;

[0058] Figure 8 is a current curve diagram of a magnetorheological buffer under a certain working condition obtained based on simulation in an embodiment of the present invention;

[0059] Figure 9 This is a comparison diagram of the current curve obtained based on the method of the present invention and the current curve obtained by simulation;

[0060] Figure 10 This is a graph of the magnetorheological buffer current predicted by the neural network model constructed by the present invention;

[0061] Figure 11 11a is a comparison of the output force time history of the magnetorheological buffer, and 11b is a comparison of the power of the magnetorheological buffer.

[0062] Explanation of the reference numerals: 1-lower connecting head, 2-piston rod, 3-guide, 4-actuating piston, 5-working cylinder, 6-oil chamber, 7-air chamber, 8-magnetorheological valve, 801-housing, 802-upper end cover, 803-lower end cover, 804-first excitation coil, 805-second excitation coil, 806-iron core, 807-conducting wire, 9-floating piston, 10-upper connecting head, 11-one-way inflation nozzle, 12-polyurethane rubber pad, 13-connecting rod, 14-cylinder end cover. DETAILED DESCRIPTION

[0063] The following describes in detail embodiments of the present invention. The embodiments are exemplary and intended to explain the present invention, but are not to be construed as limiting the present invention.

[0064] Reference Figure 1 and Figure 2An embodiment of the present invention provides a magnetorheological valve, comprising a housing 801, an upper end cover 802, a lower end cover 803, a first excitation coil 804, a second excitation coil 805, an iron core 806, and a conductive wire 807. The iron core 806 is embedded in the cavity of the housing 801, and a gap is formed between the outer wall of the iron core and the inner wall of the housing 801, forming an annular oil damping channel. Two annular coil slots are symmetrically provided on the outer wall of the iron core. The first excitation coil 804 and the second excitation coil 805 are formed by winding a conductive wire 807 in the two annular coil slots. The first excitation coil 804 and the second excitation coil 805 are wound in opposite directions, so that the two coils can generate magnetic circuits in opposite directions. Both magnetic circuits can generate magnetic induction intensities perpendicular to the oil damping channel. The magnetic induction intensities at the position between the two coil slots are superimposed and enhanced, thereby greatly improving the utilization efficiency of the radial magnetic field in the oil damping channel. In this embodiment, the first excitation coil and the second excitation coil are wound with a total of 260 turns. After winding, they are treated with vacuum paint to improve the insulation strength of the coil and prevent the magnetorheological fluid from directly contacting the coil and corroding the coil.

[0065] The iron core 806 has a central hole with two large sections and a smaller center hole along its axis. The wire 807 is wound in the two annular coil slots and then led out from the central hole of the iron core for connection to an external power supply.

[0066] The upper and lower end caps 802 and 803 have identical appearances and are mounted on either end of the housing 801. Four arcuate holes, evenly distributed around the circumference of each end cap, allow external magnetorheological fluid to pass through and enter the annular oil damping channel between the housing 801 and the core 806. The upper end cap 802 has a central through-hole for the passage of a wire 807. This wire 807 is routed through the core's central hole and the upper end cap's central through-hole before being connected to an external power source.

[0067] The iron core 806 and shell 801 of the magnetorheological valve are made of electrical pure iron with high magnetic permeability, and the upper end cover 802 and lower end cover 803 are made of 304 stainless steel with low magnetic permeability. The purpose is to concentrate the magnetic lines of force loop in the iron core, oil damping channel and shell, reduce the magnetic lines of force entering the upper end cover, lower end cover and external air, and maximize the use of the radial magnetic field generated by the excitation coil in the oil damping channel.

[0068] In order to verify and analyze the magnetic induction intensity distribution of the magnetorheological valve designed in the embodiment of the present invention, a constant DC current of 1A was passed through the magnetorheological valve in this embodiment, and the radial magnetic induction intensity at different axial depths of the oil damping channel under the same oil hole was measured through experiments and simulations. Figure 3It can be seen that the radial magnetic induction intensity in the oil damping channel of the magnetorheological valve is symmetrically distributed about the middle position of the oil damping channel. The direction of the magnetic induction intensity at the inlet and outlet of the oil damping channel is opposite to that at the middle position, and there are regions of uniform magnetic field intensity. The magnetic induction intensity at the inlet and outlet positions is smaller than that at the middle position. Specifically, along the axial direction of the oil damping channel, the radial magnetic induction intensity of the oil damping channel gradually increases at a depth of 0-10mm. At a position near 10mm, the magnetic induction intensity remains at the same level of approximately 60mT. At a depth of 15-20mm, the magnetic induction intensity gradually decreases until it reaches 0, at which point the magnetic field direction is opposite. When the oil damping channel depth is 20-25mm, the magnetic induction intensity gradually increases until it reaches a maximum value. At a depth of 25-35mm, that is, in the middle of the damping channel, the magnetic induction intensity always maintains a maximum value of approximately 70mT. The magnetic induction intensity of the oil damping channel with a depth of 35-60 mm is symmetrically distributed with the oil damping channel with a depth of 0-25 mm. Figure 3 The experimental data of medium magnetic field are in close agreement with the simulation data, which proves the effectiveness of the simulation analysis.

[0069] Reference Figure 4 and Figure 5 The embodiment of the present invention also provides a magnetorheological buffer for aircraft landing gear, including a lower connector 1, a piston rod 2, a guide 3, an actuating piston 4, a working cylinder 5, a magnetorheological valve 8, a floating piston 9, an upper connector 10, an inflation nozzle 11, a polyurethane rubber pad 12, a connecting rod 13 and a cylinder end cover 14. Definition Figure 4 and Figure 5 The upper part of the magnetorheological buffer is on the right side of the middle image, and the lower part of the magnetorheological buffer is on the left side.

[0070] The working cylinder 5 comprises a working chamber, comprising an air chamber 7 at the top and an oil chamber 6 connected to the air chamber at the bottom. The air chamber is pre-filled with nitrogen, and the oil chamber is pre-filled with magnetorheological fluid, with the amount of fluid being at least sufficient to cover the magnetorheological valve 8. The magnetorheological valve 8 is disposed within the oil chamber and coaxially connected to an upper connector 10 at the upper end of the working cylinder 5 via a connecting rod 13. This prevents direct connection between the magnetorheological valve and the working cylinder from damaging the working cylinder. To prevent the presence of gas from affecting the buffering effect during oil-gas mixing, a floating piston 9 is mounted on the connecting rod 13 in this embodiment. The floating piston 9 can slide along the connecting rod 13 to ensure separation of the oil and gas. Specifically, one end of the connecting rod 13 is fixedly connected to the upper end cap 802 and the iron core of the magnetorheological valve 8 via threads, while the other end is axially fixed to the inner wall of the upper connector 10. The upper connector 10 has a central through-hole. A wire 807 extends through the central hole of the connecting rod 13 and the central through-hole of the upper connector 10, extending out of the working cylinder and connecting to an external power source. This prevents the wire from coming into contact with the magnetorheological fluid, which could corrode it and shorten its service life. A one-way inflation nozzle 11 is mounted on the outer wall of the upper end of the working cylinder for injecting nitrogen into the air cavity 7 to regulate the pressure within the cavity.

[0071] The coaxially connected piston rod 2 and the actuating piston 4 are installed in the lower part of the working cylinder, and the actuating piston 4 is located in the oil chamber 6 of the working cylinder 5. The magnetorheological buffer realizes the extension or compression stroke through the actuating piston. The lower end of the working cylinder is successively installed with a cylinder end cover 14 and a polyurethane rubber pad 12 to prevent the lower connector 1 from colliding with the cylinder end cover 14. The piston rod 2 is provided with a guide 3, and the guide is located between the actuating piston 4 and the cylinder end cover 14, which is used to provide a guiding effect for the movement of the piston rod and ensure the coaxiality of the piston rod movement. The protruding end of the piston rod 2 is threadedly connected to a coaxially arranged lower connector 1, which is used to connect the magnetorheological buffer to the aircraft landing gear wheel; the upper connector 10 is connected to the connection position between the aircraft landing gear and the aircraft body.

[0072] The operating principle of the magnetorheological damper designed in this embodiment of the present invention is as follows: When the damper is pressurized, the actuating piston 4 pushes the magnetorheological fluid through the fan-shaped through-holes in the lower end cap of the magnetorheological valve and into the oil damping channel. The magnetic induction intensity in the oil damping channel can be adjusted by the current in the excitation coil, thereby changing the shear yield stress of the magnetorheological fluid flowing through the oil damping channel, and thus the fluid viscosity, thereby controlling the damping force of the magnetorheological damper. During the movement of the actuating piston, part of the aircraft landing energy is dissipated as damping heat, and the remaining part is stored as potential energy in the air cavity of the working cylinder 5. When the nitrogen in the air cavity is compressed to a certain level, the air cavity pressure exceeds the pressure of the actuating piston 4, and the damper begins its extension stroke. The magnetorheological fluid enters the oil damping channel through the fan-shaped through-holes in the upper end cap of the magnetorheological valve, generating a damping force. The aircraft landing energy is again dissipated as heat until the air cavity pressure is insufficient to support the damper's extension movement. In this reciprocating motion, the buffer dissipates the aircraft's landing energy through the compression and extension stroke of the actuating piston, thereby reducing the shock load on the aircraft's landing gear.

[0073] Design ideas of the magnetorheological buffer control method according to the embodiment of the present invention:

[0074] Due to the magnetorheological effect of magnetorheological fluid, as the external magnetic induction intensity increases, the shear yield stress of the magnetorheological fluid increases, manifesting as an increase in oil viscosity, thereby increasing the damping force of the magnetorheological damper. Based on a neural network model, the present invention generates preset current curves for different drop shock conditions to control the damper's output force, maintaining a constant output force and achieving a "plateau" effect. This improves the damping efficiency of the damper and achieves optimal damping performance.

[0075] By constructing a landing gear drop dynamics model including the above-mentioned magnetorheological damper, the damping force of the magnetorheological damper, the air spring force, and the wheel spring force are obtained through parameter identification to obtain a specific relationship expression, and the landing gear drop dynamics response is solved. The expression that affects the output force of the magnetorheological damper is: , that is, the output force of the magnetorheological buffer can be determined by the buffer compression , compression speed and the excitation coil current

[0076] To improve the buffering efficiency of the MR buffer, it is necessary to make the power curve of the MR buffer tend to be rectangular, to ensure that the output force of the MR buffer remains constant, and to present a "platform" effect, that is, to ensure that the output force of the MR buffer changes with the compression of the buffer. and compression speed The output force remains unchanged , is the optimal expected damping force of the magnetorheological buffer. When the external power supply is applied, The current I, when When the current is .

[0077] The expected damping force of the magnetorheological buffer is different under different drop shock conditions.

[0078] The drop parameters (including drop mass, sinking speed and initial pressure of the buffer) are used to obtain the corresponding desired damping force. During the landing gear drop process, the motion state of the magnetorheological buffer is continuously input to make the magnetorheological buffer output force equal to the desired damping force. The current is used to keep the output force of the magnetorheological buffer constant throughout the entire falling shock process, thereby ultimately achieving a "platform" effect of the output force.

[0079] Considering that there is a time delay in the landing gear during the landing process, the current cannot be adjusted in real time according to the compression amount and compression speed of the magnetorheological buffer. Therefore, the present invention adopts a preset current method, and obtains a preset current curve under the landing condition through a neural network control algorithm. The current curve is then input into the external power control system, so that the external power control system controls and adjusts the input current of the magnetorheological buffer according to the current curve. Figure 6 The control method of the magnetorheological buffer of the present invention comprises the following steps:

[0080] Step 1: Obtain the optimal expected damping force under several landing gear drop conditions, construct an expected damping force neural network model, and train the constructed expected damping force neural network model using the drop condition parameters and the corresponding optimal expected damping force as training data. The expected damping force neural network model constructed in this step is used to predict the corresponding optimal expected damping force based on the input drop condition parameters.

[0081] Step 1.1, according to Figure 7 The established landing gear drop dynamics model can obtain the drop dynamics equation of the magnetorheological buffer landing gear two-degree-of-freedom system:

[0082]

[0083] in, is the sprung mass, including the total mass of the buffer outer tube, the basket (corresponding to the mass of the aircraft body) and their connecting parts; The unsprung mass includes the mass of the piston rod, the wheel and its connected parts.

[0084] is the output force of the magnetorheological buffer, is the wheel elastic force; is the displacement of the sprung mass, is the displacement of the unsprung mass; the compression of the magnetorheological buffer , the compression speed of the magnetorheological buffer is .

[0085] The coordinate origin is the position of the sprung mass block and the unsprung mass block when the landing gear is fully extended and the wheels just touch the ground, and the vertical upward direction is defined as the positive direction. Since the compression amount and compression speed of the magnetorheological buffer will change continuously with the change of the landing gear drop height during the landing shock process, the output force of the magnetorheological buffer can be obtained , that is, the output force of the magnetorheological buffer can be determined by the compression , compression speed and the excitation coil current According to the output force expression of magnetorheological buffer It can be seen that when the compression amount and compression speed are constantly changing, the output force of the MR buffer can be kept constant by adjusting the current. Next, we determine the optimal expected damping force to keep the output force of the MR buffer constant:

[0086] Determine several drop shock working conditions, traverse and determine the expected damping force for each drop shock working condition, and calculate the buffering efficiency of the magnetorheological buffer corresponding to the expected damping force according to the formula:

[0087] The calculation formula of the buffering efficiency of the magnetorheological buffer is:

[0088]

[0089] Where, The moment when the first compression stroke of the magnetorheological buffer ends; is the maximum output force of the magnetorheological buffer; is the maximum value of the compression of the magnetorheological buffer; The output force of the magnetorheological buffer at any time within the first compression stroke, is the compression amount of the magnetorheological buffer at any time within the first compression stroke.

[0090] In step 1.2, all expected damping forces and their corresponding MR damping efficiencies are traversed, and the expected damping force corresponding to the highest MR damping efficiency is taken as the optimal expected damping force for the current drop condition.

[0091] Step 1.3: Obtain the optimal expected damping force corresponding to multiple drop vibration conditions according to step 1.2.

[0092] In step 1.4, the constructed expected damping force neural network model is trained using the drop vibration working condition parameters and the corresponding optimal expected damping force as training parameters, so that the neural network model of the constructed expected damping force neural network model memorizes the input-output relationship between the drop vibration working condition parameters and the optimal expected damping force.

[0093] Step 2: Construct a current time characteristic neural network model and a current numerical characteristic neural network model, and train and predict the current time characteristic neural network model and the current numerical characteristic neural network model to obtain the time characteristic data and numerical characteristic data of the magnetorheological buffer input current under different drop shock conditions. Specifically, the following steps are included:

[0094] Step 2.1, based on the output force expression of the magnetorheological damper The current time characteristic neural network model and the current numerical characteristic neural network model are constructed respectively, where the formula middle is the output force of the magnetorheological buffer, is the compression of the magnetorheological buffer, is the compression speed of the magnetorheological buffer, Input current to the magnetorheological buffer;

[0095] The constructed current time characteristic neural network model is used to output the corresponding time characteristics of the magnetorheological buffer input current according to the input drop shock working condition parameters and the corresponding optimal expected damping force.

[0096] The constructed current numerical characteristic neural network model is used to output the corresponding numerical characteristics of the magnetorheological buffer input current according to the input drop shock working condition parameters and the corresponding optimal expected damping force.

[0097] Step 2.2, in this embodiment, simulation is first used to obtain the time characteristic data and numerical characteristic data of the magnetorheological buffer input current under several drop shock conditions of the aircraft landing gear. Then, the parameters of each drop shock condition, the corresponding optimal expected damping force predicted and output by the expected damping force neural network model in step 1, and the time characteristic data or numerical characteristic data of the magnetorheological buffer input current are used as training data to train the constructed current time characteristic neural network model and current numerical characteristic neural network model respectively, so that the constructed current time characteristic neural network model and current numerical characteristic neural network model are trained to respectively memorize the corresponding input-output relationship. After training, the current time characteristic neural network model and the current numerical characteristic neural network model can respectively predict and output the current time characteristic and current numerical characteristic under the corresponding drop shock condition based on any drop shock condition parameters and the corresponding optimal expected damping force.

[0098] Figure 8The current-time characteristic curve of the magnetorheological buffer under a certain working condition obtained based on simulation in this embodiment can be simplified into a curve consisting of 8 characteristic numbers, where is the time when the curve first drops, is the time when the curve drops to the minimum value, is the time when the curve reaches its maximum value, is the second descending time of the curve, is the time when the curve drops to the minimum value for the second time, is the time when the curve reaches its maximum value again, and is the size of the first valley value, is the size of the second valley value. From this we can see that as long as we get these eight eigenvalues, we can fit each curve segment with a quadratic function to obtain the current-time curve.

[0099] In step 2.3, the current time characteristic neural network model and the current numerical characteristic neural network model are used to predict and output the time characteristic data and numerical characteristic data of the magnetorheological buffer input current corresponding to different drop shock conditions.

[0100] Step 3: Use the quadratic function fitting method to fit the time characteristic data and numerical characteristic data of the magnetorheological buffer input current under the same drop shock working condition obtained in step 2 to obtain the current-time curve of the magnetorheological buffer in the corresponding drop shock working condition.

[0101] Figure 9 The figure shows a comparison of the current curve obtained under a certain drop shock condition based on the method of the present invention and the current curve obtained by simulation. As can be seen from the figure, the current curve obtained based on the prediction of the neural network model and the data fitting method of the present invention is basically consistent with the current curve obtained by simulation, indicating the reliability of the current control curve obtained by the method of the present invention. By analyzing and statistically analyzing the current curves obtained by the method of the present invention and the simulation method under multiple drop shock conditions, the prediction accuracy of the time feature neural network model is 94.78%, and the prediction accuracy of the numerical feature neural network model is 95.53%, which proves the effectiveness of the neural network model method of the present invention.

[0102] Step 4: preset the current-time curve of the lower magnetorheological buffer in each drop shock condition obtained in step 3 in the external power supply controller. The power supply controller controls and adjusts the input current of the magnetorheological buffer according to the preset current-time curve of the magnetorheological buffer, so that the output force of the magnetorheological buffer is always equal to the optimal expected damping force of the magnetorheological buffer, thereby realizing adaptive adjustment of the damping force of the magnetorheological buffer.

[0103] In order to verify the effectiveness of the method of the present invention, a certain drop shock condition was randomly selected, in which the landing gear drop shock mass was 210kg, the sinking speed was 1m / s, and the initial pressure of the buffer air cavity was 0.6MPa. First, the expected damping force neural network model constructed by the present invention was used to predict that the optimal expected resistance under this condition was 4600N. Then, the drop shock condition parameters and the obtained optimal expected damping force corresponding to this condition were input into the constructed current time characteristic neural network model and current numerical characteristic neural network model, and the time characteristic data and numerical characteristic data of the current were predicted respectively. Finally, the obtained time characteristic data and numerical characteristic data were fitted with a quadratic function to obtain the input current curve of the magnetorheological buffer. The current curve is shown in the figure below. Figure 10 The current-time curve obtained by the method of the present invention is input into the constructed landing gear drop dynamics simulation model to obtain the output force time history curve and work curve of the magnetorheological buffer.

[0104] Figure 11 The output force time history and power curves of the MR damper obtained using the present invention's method are compared with those obtained using a conventional on-off control method. 11a shows the output force time history of the MR damper, while 11b shows the power history of the MR damper. The output force history curves show that, under the same landing gear drop shock condition, the peak output force of the MR damper using the conventional on-off control method is 6249.5N; while the peak output force of the MR damper using the present invention's control method is 4505.7N. This reduces the peak output force by 27.9% while maintaining a constant output force, achieving a "plateau" effect for the output force. It can be seen from the work curve that the buffering efficiency of the magnetorheological buffer is 61.86% when the traditional on-off method is used for control, while the buffering efficiency of the magnetorheological buffer reaches 95.10% when the method of the present invention is used for control. This shows that the control method of the present invention can effectively improve the buffering efficiency of the magnetorheological buffer, proving the superiority of the magnetorheological buffer designed by the present invention and the control method of the present invention.

[0105] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present invention, and these modifications or replacements should all be included in the scope of protection of the present invention.

Claims

1. A magnetorheological buffer control method, characterized in that: Based on the implementation of magnetorheological dampers for aircraft landing gear; The magnetorheological buffer for aircraft landing gear includes a working cylinder, a first connector, a cylinder end cover, a piston rod, a guide, an actuating piston, a connecting rod, a floating piston, an inflation nozzle, a second connector, and a magnetorheological valve; The working cylinder has a working cavity, including an oil cavity and an air cavity that are connected; One end of the piston rod is connected to the actuating piston and is located in one end of the oil chamber, and the other end of the piston rod is located outside the working cylinder and is fixedly connected to the first connector; The cylinder end cover is coaxially sealed and mounted on one end of the working cylinder, and the guide is nested on the piston rod body and is located between the cylinder end cover and the actuating piston; The magnetorheological valve is located at the other end of the oil chamber, and the second end cover of the magnetorheological valve is connected to a second connector coaxially mounted on the other end of the working cylinder barrel via the connecting rod; the connecting rod has a central through hole for allowing the wire of the magnetorheological valve to extend out of the working cylinder barrel; The oil cavity is filled with magnetorheological fluid, and the amount of the magnetorheological fluid injected must at least cover the magnetorheological valve; The air cavity is filled with gas through the inflation nozzle; The floating piston is sleeved on the rod body of the connecting rod and can slide along the connecting rod under the action of the gas in the air cavity to separate the magnetorheological fluid from the gas; The first connector is used to connect one end of the magnetorheological buffer to the aircraft landing gear wheel, and the second connector is used to install the other end of the magnetorheological buffer at the connection position between the aircraft landing gear and the aircraft body; The control method comprises the following steps: Step 1: Obtain the optimal expected damping force under several landing gear drop conditions, construct an expected damping force neural network model, and train the constructed expected damping force neural network model using the drop condition parameters and the corresponding optimal expected damping force as training data; The expected damping force neural network model is used to predict the optimal expected damping force corresponding to the output according to the input drop shock working condition parameters; The drop condition parameters include drop mass, sinking speed and initial pressure of the buffer; Step 2: Construct a current time characteristic neural network model and a current numerical characteristic neural network model, and train and predict the current time characteristic neural network model and the current numerical characteristic neural network model to obtain the time characteristic data and numerical characteristic data of the magnetorheological buffer input current under different drop shock conditions: Step 2.1, based on the output force expression of the magnetorheological damper The current time characteristic neural network model and the current numerical characteristic neural network model are constructed respectively, where the formula middle is the output force of the magnetorheological buffer, is the compression of the magnetorheological buffer, is the compression speed of the magnetorheological buffer, Input current to the magnetorheological buffer; The current time characteristic neural network model is used to output the corresponding time characteristic of the magnetorheological buffer input current according to the input drop shock working condition parameters and the corresponding optimal expected damping force; The current numerical characteristic neural network model is used to output the corresponding numerical characteristics of the magnetorheological buffer input current according to the input drop shock working condition parameters and the corresponding optimal expected damping force; Step 2.2, obtaining time characteristic data and numerical characteristic data of the magnetorheological damper input current under several landing gear drop conditions, using the parameters of each drop condition, the corresponding optimal expected damping force predicted and output by the expected damping force neural network model, and the time characteristic or numerical characteristic data of the magnetorheological damper input current as training data, to train the current time characteristic neural network model and the current numerical characteristic neural network model respectively; Step 2.3, respectively predicting and outputting the time characteristic data and the numerical characteristic data of the magnetorheological buffer input current corresponding to different drop shock conditions through the current time characteristic neural network model and the current numerical characteristic neural network model; Step 3: Fitting the time characteristic data and the numerical characteristic data of the input current of the magnetorheological buffer under the same drop shock working condition obtained in step 2 to obtain the current-time curve of the magnetorheological buffer under the corresponding drop shock working condition; Step 4: The current-time curve of the magnetorheological buffer in each drop shock working condition obtained in step 3 is preset in the external power supply controller. The power supply controller controls and adjusts the input current of the magnetorheological buffer according to the preset current-time curve of the magnetorheological buffer, so that the output force of the magnetorheological buffer is equal to the optimal expected damping force of the magnetorheological buffer, thereby realizing adaptive adjustment of the output force of the magnetorheological buffer.

2. A magnetorheological damper control method according to claim 1, characterized in that: In step 1, the specific process of obtaining the optimal expected damping force under several landing conditions of the aircraft landing gear is as follows: Step 1.1: traverse and obtain the expected damping force for each drop shock working condition, and calculate the buffering efficiency of the magnetorheological buffer corresponding to the expected damping force according to the formula: The calculation formula of the buffering efficiency of the magnetorheological buffer is: Where, The moment when the first compression stroke of the magnetorheological buffer ends; is the maximum output force of the magnetorheological buffer; is the maximum compression amount of the magnetorheological buffer; The output force of the magnetorheological buffer at any time within the first compression stroke, is the compression amount of the magnetorheological buffer at any time within the first compression stroke; Step 1.2: traverse all expected damping forces and their corresponding MR damper efficiencies, and take the expected damping force corresponding to the highest MR damper efficiency as the optimal expected damping force under the current drop condition; Step 1.3: Obtain the optimal expected damping force corresponding to each drop condition according to the method in step 1.

2.

3. The magnetorheological damper control method according to claim 1, characterized in that: In the step 2.2, the time characteristic data and the numerical characteristic data of the input current of the magnetorheological buffer under several landing conditions of the aircraft landing gear are obtained based on the simulation.

4. A magnetorheological valve, characterized in that: The magnetorheological valve is used for the magnetorheological buffer for aircraft landing gear controlled by the control method according to any one of claims 1 to 3, and the magnetorheological valve includes a housing, a first end cover, a second end cover, a first excitation coil, a second excitation coil, an iron core, a wire, and a magnetorheological fluid; The iron core is coaxially mounted in the cavity of the housing, and a gap exists between the outer wall of the iron core and the inner wall of the housing to form an annular oil damping channel; the iron core has a central hole opened along its axis; Two annular coil slots are symmetrically provided on the outer wall of the iron core. The first excitation coil and the second excitation coil are formed by winding a wire in the two annular coil slots. After winding, the free end of the wire is led out of the iron core through the central hole of the iron core. The winding directions of the first excitation coil and the second excitation coil are opposite. The first end cover and the second end cover are coaxially nested at both ends of the housing, and a plurality of arc-shaped holes are circumferentially provided on the end surfaces of the first end cover and the second end cover for the magnetorheological fluid to pass through and enter the annular oil damping channel; The second end cover has a central through hole coaxial with the central hole of the iron core, for the wire to pass through and extend out of the shell to connect to an external power source.

5. The magnetorheological valve according to claim 4, characterized in that: The first excitation coil and the second excitation coil are treated with vacuum paint to improve the insulation strength of the excitation coils.

6. The magnetorheological valve according to claim 5, characterized in that: The iron core and the shell are made of electrical pure iron; the first end cover and the second end cover are made of stainless steel.

7. A magnetorheological buffer for aircraft landing gear, characterized in that: The magnetorheological buffer for aircraft landing gear is controlled by the control method according to any one of claims 1 to 3, and includes the magnetorheological valve according to any one of claims 4 to 6.

8. The magnetorheological buffer for aircraft landing gear according to claim 7, characterized in that: The center hole of the iron core is a multi-step hole, wherein one end of the center hole is a threaded hole for threaded connection with the connecting rod.

9. The magnetorheological buffer for aircraft landing gear according to claim 8, characterized in that: After the connecting rod is connected to the threaded hole and the central through hole of the second end cover of the magnetorheological valve, it is sealed with hot melt adhesive to fix the wire located in the central hole of the iron core.

10. The magnetorheological damper for aircraft landing gear according to claim 9, characterized in that: It also includes a polyurethane rubber pad, which is located at the end of the cylinder end cover and is coaxially connected to the cylinder end cover to prevent the cylinder end cover from colliding with the first connecting head.

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