A multi-degree-of-freedom high-frequency motion simulation device for aircraft dynamic stability test and a method for calculating actuating angles

Abstract

The present application belongs to the field of wind tunnel experiment under hypersonic flow field environment, and discloses a multi-degree-of-freedom high-frequency motion simulation device for aircraft dynamic stability test and a method for realizing actuation angle calculation. The technical method is based on the electromechanical coupling equation determined by the electrical parameters and mechanical parameters of the piezoelectric material for calculation. According to the piezoelectric equation, the calculation method between the voltage applied by the piezoelectric actuator and the actuation angle of the device in pitch and yaw can be modeled, so as to accurately control and predict the excitation effect of the device during the ground test. The method is not only suitable for the actuation calculation of the two-degree-of-freedom pitch and yaw, but also can calculate the actuation angle of the three-axis degree-of-freedom experimental device by coordinate transformation under the condition of adding roll speed and other parameters. At present, the calculation method based on the device only considers the two-axis degree-of-freedom of pitch and yaw for calculation.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of wind tunnel experiment under hypersonic flow field environment, and relates to a multi-degree-of-freedom high-frequency motion simulation device for aircraft dynamic stability experiment and a method for calculating actuation angle. BACKGROUND

[0002] In the development process of high-performance aircraft such as supersonic fighter, wind tunnel experiment as an essential key technology plays an extremely important role. Wind tunnel experiment simulates the airflow environment of aircraft under different flight conditions, and provides important technical support for guiding the development of aircraft aerodynamic layout. However, in the high-speed flow field environment, the slight attitude change or slight airflow disturbance of the aircraft during flight can induce the instantaneous change of aerodynamic load, leading to the divergence of flight attitude oscillation, and the control system is difficult to respond and adjust in time, which seriously threatens the flight stability and service safety. Therefore, it is very important to carry out dynamic stability simulation test for high-performance aircraft such as supersonic aircraft. The core of dynamic stability simulation test is to simulate the motion state of aircraft under disturbance by exciting the scaled model, so as to obtain the key parameters such as aerodynamic force load. At the same time, the key data obtained through dynamic stability simulation experiment in high-speed wind tunnel environment can guide the aerodynamic layout design of aircraft, so as to improve the limit maneuvering performance of aircraft, and further effectively ensure the service stability and safety of aircraft. In the dynamic stability simulation test in high-speed wind tunnel, the traditional experimental device can only realize single-degree-of-freedom motion simulation, not only has the problem of low motion simulation quality due to poor adaptability of single-degree-of-freedom system, but also in order to obtain complete dynamic stability test data of aircraft, the test equipment must be frequently started and stopped for disassembly, replacement of parts, which seriously affects the test efficiency and increases the test cost. Although the motion simulation system for low-speed wind tunnel dynamic stability experiment can meet the demand of multi-degree-of-freedom motion simulation, but due to its large device volume and low actuation frequency, it cannot adapt to the experimental environment of narrow space in high-speed wind tunnel. Therefore, the traditional experimental device cannot realize multi-degree-of-freedom high-frequency motion simulation in high-speed wind tunnel environment through single test. Based on the above problems, in order to meet the experimental requirements of wind tunnel experiment, it is urgent to develop and design a multi-degree-of-freedom high-frequency motion simulation device for aircraft dynamic stability experiment.

[0003] The patent "A Resonant Excitation Device" (patent number CN201320425874.2) by Fu Zengliang et al. of the China Academy of Aerospace Aerodynamics describes a resonant excitation device comprising a servo motor, bevel gears, cylindrical gears, elastic hinges, and a balance. This device primarily utilizes the transmission between the bevel gear pair and the rack and pinion pair to achieve the conversion and reversal of the servo motor's rotation into the resonant motion of the driving model. The device has a simple structure and small cross-sectional installation size, meeting the experimental requirements of the confined space in high-speed wind tunnel tests. Furthermore, its high reciprocating motion positioning accuracy satisfies the basic experimental requirements for determining the dynamic stability of high-speed wind tunnel aircraft. However, this device only converts the servo motor's rotation into the linear motion of the elastic beam push rod connected to the rack, achieving only a single degree of freedom resonant excitation. This results in poor adaptability of experimental data, making it difficult to obtain complete dynamic stability test data for the aircraft. This experimental device cannot simulate the multi-degree-of-freedom high-frequency motion of the aircraft.

[0004] Xue Dong et al. from the Xi'an Modern Control Technology Research Institute introduced a novel dynamic derivative measurement and calibration device using an elastic hinge in their patent "A Novel Dynamic Derivative Elastic Hinge Calibration Device" (patent number CN202123287802.X). This device mainly includes two laser displacement sensors, a sensor mounting bracket, a crossbar, a turntable, a support, legs, and a sleeve. It can achieve rapid and accurate calibration of the elastic hinge in the yaw direction. Compared with traditional dynamic derivative measurement devices, its advantages lie in its ability to measure and calibrate multi-degree-of-freedom motion, and the fact that the entire experimental process does not require manual data reading, resulting in high automation efficiency. Furthermore, this experimental equipment avoids frequent disassembly and assembly during the experiment, effectively saving experimental costs and improving efficiency. However, this experimental equipment suffers from the limitation of excessive size, making it difficult to adapt to the narrow experimental requirements of high-speed wind tunnel testing spaces.

[0005] Based on the problems existing in the current technology, it is necessary to design a multi-degree-of-freedom high-frequency motion simulation device for aircraft dynamic stability testing. The device should be able to realize multi-degree-of-freedom motion simulation while taking into account the limitations of the small test space in high-speed wind tunnels. Summary of the Invention

[0006] The purpose of this invention is to provide a multi-degree-of-freedom high-frequency motion simulation device for aircraft dynamic stability testing. This device primarily utilizes the inverse piezoelectric effect to excite a piezoelectric actuator, generating actuation force. A flexible spring serves as the energy transfer and amplification device, leveraging resonance to amplify the excitation effect. A linkage transmission structure then converts the axial displacement into an actuation angle, simulating the device's motion. Simultaneously, a cylinder mounted in the excitation section provides damping force. This device overcomes the shortcomings of existing experimental devices, such as motion simulation distortion in high-speed wind tunnels and the waste of experimental resources due to frequent disassembly and reassembly, thereby improving experimental results.

[0007] The technical scheme of the present application:

[0008] A multi-degree-of-freedom high-frequency motion simulation device for aircraft dynamic stability test and a method for calculating actuating angle, first, a flexible spring is screwed to the front end of the excitation section; then, a piezoelectric actuator is assembled to the cavity of the excitation section, and the piezoelectric actuator is required to be tightly attached to the front end of the cavity of the excitation section and connected with the flexible spring at the unconnected end; secondly, a moving base, an inclined concave block, an inclined pre-tightening block are sequentially assembled at the connected end of the piezoelectric actuator, and the inclined pre-tightening block is screwed to provide axial pre-tightening force for the piezoelectric actuator, so as to reduce transmission gap and improve transmission accuracy of the piezoelectric actuator; then, a gas cylinder and a gas pipe are assembled into the excitation section to provide damping force for the experimental device; subsequently, a bow shaft, a vibration head, a force measuring balance and a chisel block are sequentially assembled at the head of the excitation section to stably connect the force measuring balance and the vibration head. Thus, the assembly of the device is completed. The core structure of the device is a coupled resonance mechanism composed of the piezoelectric actuator and the flexible spring, the mechanism generates actuating force by the piezoelectric actuator as an excitation source, and uses the flexible spring as a transmission and amplification device of actuating energy to improve excitation effect by resonance effect.

[0009] A multi-degree-of-freedom high-frequency motion simulation device for aircraft dynamic stability test, comprising an excitation section 1, a bow shaft 2, a vibration head 3, a chisel block 4, an inclined pre-tightening block 5, a piezoelectric actuator 6, an inclined concave block 7, a moving base 8, a gas cylinder 9, a force measuring balance 10, a gas pipe 11 and a flexible spring 12;

[0010] The excitation section 1 is in a cylindrical structure, four fan-shaped cavities are opened on the excitation section 1, and two square cavities are opened in the excitation section 1; the four fan-shaped cavities are used to load the piezoelectric actuator 6, the inclined concave block 7, the moving base 8 and the inclined pre-tightening block 5, and the two square cavities are used to load the gas cylinder 9; a through hole is opened on the side wall of the excitation section 1, the gas inlet of the gas cylinder 9 is connected with a gas pump through the gas pipe 11 to provide sufficient gas pressure for the gas cylinder 9; an arc-shaped protruding structure is arranged at the front end of the excitation section 1 to connect with the vibration head 3 and the bow shaft 2; a cylindrical protruding structure is arranged at the rear end of the excitation section 1 to be fixedly connected with an experimental table;

[0011] The piezoelectric actuator 6 is assembled into the fan-shaped cavity of the excitation section 1, and the moving base 8, the inclined concave block 7 and the inclined pre-tightening block 5 are sequentially assembled at the connected end of the piezoelectric actuator 6 to ensure that there is no transmission gap when the piezoelectric actuator 6 is excited in the fan-shaped cavity; the gas cylinder 9 is assembled into the square cavity of the excitation section 1, and the gas pipe 11 is connected with the gas cylinder 9; the front end of the excitation section 1 is screwed with one end of the flexible spring 12 to fixedly connect the arc-shaped protruding structure at the front end of the excitation section 1 with the bow shaft 2, the bow shaft 2 is assembled and connected with the vibration head 3, and then the other end of the flexible spring 12 is screwed and assembled with the vibration head 3; the vibration head 3 is fixedly connected with the force measuring balance 10 through the chisel block 4;

[0012] The method for calculating the actuation angle of a multi-degree-of-freedom high-frequency motion simulation device for aircraft dynamic stability test is based on the electromechanical coupling equation of piezoelectric material determined by electrical parameters and mechanical parameters. According to the piezoelectric equation, the calculation method between the voltage applied by the piezoelectric actuator and the actuation angle of the device in pitch and yaw can be modeled, so as to accurately control and predict the excitation effect of the device during ground test. This method is not only suitable for actuation calculation of two degrees of freedom in pitch and yaw, but also can calculate the actuation angle by coordinate transformation in the case of adding roll angle speed and other parameters for three-axis degree-of-freedom experimental device. At present, the calculation method based on the device only considers the pitch and yaw two-axis degree-of-freedom case for calculation.

[0013] The steps are as follows:

[0014] First step, calculate the strain of the piezoelectric actuator 6;

[0015] It is known that the multi-degree-of-freedom high-frequency motion simulation device uses four same piezoelectric actuators 6, and the piezoelectric actuator 6 used is made by bonding several polarized piezoelectric ceramic sheets. In the case of determining the electrical parameters and mechanical parameters of the piezoelectric actuator 6 material, according to the piezoelectric equation, the elongation of a single piezoelectric actuator 6 under a given voltage is:

[0016] (1)

[0017] (2)

[0018] In the formula: is the strain; is the elastic compliance constant of the piezoelectric ceramic sheet when the electric field intensity is constant; is the stress; is the piezoelectric strain constant of a single piezoelectric ceramic sheet; is the voltage applied to the piezoelectric ceramic sheet, ignoring the voltage difference between the two ends of each piezoelectric ceramic sheet; is the thickness of the piezoelectric ceramic sheet; is the elongation of a single piezoelectric actuator 6; is the cross-sectional area of a single piezoelectric actuator 6; is the output force of a single piezoelectric actuator 6; is the number of piezoelectric ceramic sheets contained in a single piezoelectric actuator 6, is the original length of a single piezoelectric actuator 6;

[0019] Second step, calculate the actuation angle;

[0020] The circular plane of the vibration head 3 away from the exciting section 1 is taken as the reference rigid plane for the calculation of the actuation angle. A plane rectangular coordinate system is established on the rigid plane, and the center of the circular plane is taken as the origin of the rectangular coordinate system. The geometric center line of the piezoelectric actuators 6 on the opposite sides is taken as the x-axis direction of the rectangular coordinate system, and the y-axis direction of the rectangular coordinate system is obtained according to the right-hand rule.

[0021] According to the elongation formula of the piezoelectric actuators 6 coupled with the flexible spring 12, the relative angle of the piezoelectric actuators 6 acting on the force balance 10, i.e. the actuation angle, is calculated:

[0022] (3)

[0023] (4)

[0024] (5)

[0025] In the formula: is the center distance of the piezoelectric actuators 6 on the opposite sides among the four circumferentially distributed piezoelectric actuators 6; is the difference in elongation of the piezoelectric actuators 6 on the opposite sides in the x-axis direction; is the difference in elongation of the piezoelectric actuators 6 on the opposite sides in the y-axis direction; is the deflection angle of the rigid plane around the y-axis; is the deflection angle of the rigid plane around the x-axis; is the deflection angle of the four piezoelectric actuators 6 after coupling;

[0026] Third step, establish angle-control voltage control equation;

[0027] By combining equations (1), (2), (3), (4), and (5), we get:

[0028] (6)

[0029] In the formula: U1, U2 are the voltages applied to the two ends of the piezoelectric actuators 6 in the x-axis direction; U3, U4 are the voltages applied to the two ends of the piezoelectric actuators 6 in the y-axis direction.

[0030] The beneficial effects of the present application: the present application proposes a kind of multi-degree-of-freedom high-frequency motion simulation device for aircraft dynamic stability test realizes the calculation method of actuating angle, with piezoelectric actuator as excitation source, and the coupling resonance of flexible spring is realized to realize the transmission and amplification of actuating energy.The device realizes the motion simulation of two-axis freedom of pitch and yaw through four axial radiation distribution power sources and corresponding transmission mechanism, overcomes the disadvantages of existing experimental devices, such as difficult multi-degree-of-freedom motion simulation under high-speed wind tunnel, frequent disassembly of equipment and waste of experimental resources, while meeting the volume limit of test equipment in high-speed wind tunnel test environment.In order to realize the precise control of the device, the actuating angle of the device is calculated based on piezoelectric equation, which is convenient for users to quickly realize the programming of related control algorithm and realize the precise control of the device. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is a kind of multi-degree-of-freedom high-frequency motion simulation device for aircraft dynamic stability test schematic diagram;

[0032] Figure 2 It is the geometric relationship diagram of deflection angle calculation, wherein (a) is the three-dimensional projection view of the core actuating component of the device, (b) is the left view of the core actuating component of the device, (c) is the deflection process and deflection angle schematic diagram of piezoelectric actuator, and (d) is the voltage applied to the two ends of the four piezoelectric actuators;

[0033] Figure 3 It is the calculation flow chart of the actuating angle of the device;

[0034] Figure 4 It is the structure schematic diagram of the excitation section;

[0035] In the figure: 1-excitation section, 2-bow axis, 3-vibration head, 4-chisel block, 5-oblique pre-tightening block, 6-piezoelectric actuator, 7-oblique concave block, 8-moving base, 9-cylinder, 10-dynamometer, 11-air pipe, 12-flexible spring. DETAILED DESCRIPTION

[0036] The specific embodiments of the present application are further illustrated in combination with the drawings and technical solutions.

[0037] EMBODIMENT

[0038] The center distance of the angular piezoelectric actuator 6 is 48mm, the length of the excitation section 1 is 205mm, the original length of the flexible spring 12 is 40mm, and the length of the piezoelectric actuator 6 is 164mm.

[0039] The installation steps of a kind of multi-degree-of-freedom high-frequency motion simulation device for aircraft dynamic stability test are as follows:

[0040] The flexible spring 12 is assembled to the front end of the excitation section 1, the sector-shaped cavity of the excitation section 1 is assembled with the piezoelectric actuator 6, the moving base 8, the inclined concave block 7 and the inclined pre-tightening block 5. The air cylinder 9 is connected with the air pipe 11 and then assembled into the square cavity of the excitation section 1. The bow shaft 2, the flexible spring 12, the vibration head 3 and the force balance 10 are assembled to the front part of the excitation section 1. Thus, the multi-degree-of-freedom high-frequency motion simulation device for aircraft dynamic stability test is assembled.

[0041] The specific steps for calculating the actuation angle of the multi-degree-of-freedom high-frequency motion simulation device for aircraft dynamic stability test are as follows:

[0042] The first step is to determine the related parameters of the piezoelectric actuator 6 and calculate the elongation of a single piezoelectric actuator 6.

[0043] The following parameters are taken as examples for calculation:

[0044] The elastic compliance constant of the piezoelectric ceramic sheet is when the voltage is 100 V. The elastic compliance constant of the piezoelectric ceramic sheet is when the voltage is 300 V. The piezoelectric strain constant of the single piezoelectric ceramic sheet is The voltages applied to the four piezoelectric actuators 6 are .

[0045] It is assumed that the piezoelectric actuator 6 is in a mechanical free state, i.e. the output force . And a single piezoelectric actuator (6) contains 100 piezoelectric ceramic sheets, so the elongation of the piezoelectric actuator 6 connected to 100 V is 6 mm, and the elongation of the single piezoelectric actuator 6 connected to 300 V is 18 mm.

[0046] The second step is to calculate the actuation angle.

[0047] From the above calculation, the elongation of the piezoelectric actuator 6 is 12 mm, and the measured center distance r of the diagonal piezoelectric actuator 6 is 48 mm. Referring to formula (6):

[0048]

[0049] Therefore, the actuation angle can be calculated as , and the solution is .

[0050] Thus, the calculation of the actuation angle of the multi-degree-of-freedom high-frequency motion simulation device for aircraft dynamic stability test is completed.

[0051] ​A kind of multi-degree-of-freedom high-frequency motion simulation device for aircraft dynamic stability test, the transmission part is excited by piezoelectric actuator 6, flexible spring 12 is used as actuating energy transmission and amplification device, and high-frequency motion simulation of the device is realized by using resonance effect. The air cylinder 9 installed in the vibration section 1 can provide damping force for the device. This structure can complete the motion simulation of pitch and yaw two-axis freedom at the same time, so it can overcome the problem that the existing experimental device cannot complete multi-degree-of-freedom motion simulation in high-speed wind tunnel environment, and the device structure is light and simple, which can meet the volume limitation of test equipment in high-speed wind tunnel test environment, and provides an effective solution for the smooth progress of wind tunnel dynamic stability test. The proposed actuation angle calculation method can quickly and accurately control the motion of the device, so that the device can be more widely used in engineering applications.

Claims

1. A multi-degree-of-freedom high-frequency motion simulation device for aircraft dynamic stability test, characterized in that, The multi-degree-of-freedom high-frequency motion simulation device comprises a vibration excitation section (1), a bow shaft (2), a vibration head (3), a chisel block (4), an inclined pre-tightening block (5), a piezoelectric actuator (6), an inclined concave block (7), a moving base (8), an air cylinder (9), a force measuring platform (10), an air pipe (11) and a flexible spring (12); The vibration excitation section (1) is in a cylindrical structure, four fan-shaped cavities are opened on the vibration excitation section (1), and two square cavities are opened in the vibration excitation section (1); the piezoelectric actuator (6), the inclined concave block (7), the moving base (8) and the inclined pre-tightening block (5) are loaded in the four fan-shaped cavities, and the air cylinder (9) is loaded in the two square cavities; a through hole is opened on the side wall of the vibration excitation section (1), the air inlet of the air cylinder (9) is connected with an air pump through the air pipe (11) to provide air pressure for the air cylinder (9); an arc-shaped protruding structure is arranged at the front end of the vibration excitation section (1) to connect with the vibration head (3) and the bow shaft (2); a cylindrical protruding structure is arranged at the rear end of the vibration excitation section (1) to be fixedly connected with a test bench; The piezoelectric actuator (6) is assembled into the fan-shaped cavity of the vibration excitation section (1), the moving base (8), the inclined concave block (7) and the inclined pre-tightening block (5) are sequentially assembled at the wiring end of the piezoelectric actuator (6) to ensure that there is no transmission gap when the piezoelectric actuator (6) vibrates in the fan-shaped cavity; the air cylinder (9) is assembled into the square cavity of the vibration excitation section (1), and the air pipe (11) is connected with the air cylinder (9); the front end of the vibration excitation section (1) is screwed with one end of the flexible spring (12) to fixedly connect the arc-shaped protruding structure at the front end of the vibration excitation section (1) with the bow shaft (2), the bow shaft (2) and the vibration head (3) are assembled and connected, and then the other end of the flexible spring (12) is screwed and assembled with the vibration head (3); the vibration head (3) is fixedly connected with the force measuring platform (10) through the chisel block (4).

2. The multi-degree-of-freedom high-frequency motion simulator of claim 1, wherein the method for calculating the actuation angle is implemented by the processor. The steps are as follows: Firstly, a multi-degree-of-freedom high-frequency motion simulation device is constructed; Secondly, the strain of the piezoelectric actuator (6) is calculated; Since four same piezoelectric actuators (6) are used in the multi-degree-of-freedom high-frequency motion simulation device, and the piezoelectric actuators (6) are made by bonding a plurality of polarized piezoelectric ceramic sheets, under the condition that the electrical and mechanical parameters of the piezoelectric actuator (6) material are determined, the elongation of a single piezoelectric actuator (6) under a given voltage is calculated according to the piezoelectric equation: （1） （2） In the formula: is the strain; is the elastic compliance constant of the piezoelectric ceramic sheet when the electric field intensity is constant; is the stress; is the piezoelectric strain constant of the monolithic piezoelectric ceramic sheet; is the voltage applied to both ends of the piezoelectric ceramic sheet, ignoring the voltage difference between both ends of each piezoelectric ceramic sheet; is the thickness of the piezoelectric ceramic sheet; is the elongation of a single piezoelectric actuator (6); is the cross-sectional area of a single piezoelectric actuator (6); is the output force of a single piezoelectric actuator (6); is the number of piezoelectric ceramic sheets contained in a single piezoelectric actuator (6), is the original length of a single piezoelectric actuator (6); Thirdly, the actuation angle is calculated; The circular plane at the end of the vibration head (3) away from the vibration excitation section (1) is taken as a rigid plane for calculating the actuation angle, a plane rectangular coordinate system is constructed on the rigid plane, and the center of the circular plane is taken as the origin of the rectangular coordinate system, wherein the geometric center connecting line of the piezoelectric actuators (6) at the opposite positions of the four circumferentially distributed piezoelectric actuators (6) is taken as the x-axis direction of the rectangular coordinate system, and the y-axis direction of the rectangular coordinate system is obtained according to the right-hand rule; According to the elongation formula of the coupling of the piezoelectric actuator (6) and the flexible spring (12), the relative angle of the piezoelectric actuator (6) acting on the force measuring platform (10) is calculated, that is, the actuation angle: （3） （4） （5） In the formula: is the center distance of the piezoelectric actuators (6) in opposite positions among the four circumferentially distributed piezoelectric actuators (6); is the difference in elongation of the piezoelectric actuators (6) in opposite positions in the x-axis direction; is the difference in elongation of the piezoelectric actuators (6) in opposite positions in the y-axis direction; is the deflection angle of the rigid plane about the y-axis; is the deflection angle of the rigid plane about the x-axis; is the deflection angle of the four piezoelectric actuators (6) after coupling; Fourth step, angle-control voltage control equation is established; By combining (1), (2), (3), (4) and (5), we have: （6） In the formula: U1 and U2 are the voltages applied to the piezoelectric actuator (6) at both ends in the x-axis direction; U3 and U4 are the voltages applied to the piezoelectric actuator (6) at both ends in the y-axis direction.

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