Multi-degree-of-freedom high-frequency motion simulation device for aircraft dynamic stability test and calculation method for realizing actuation angle

Abstract

The invention belongs to the field of wind tunnel experiments in a hypersonic flow field environment, and discloses a multi-degree-of-freedom high-frequency motion simulation device for an aircraft dynamic stability test and a calculation method for realizing an actuation angle. According to the technical method, calculation is carried out on the basis of an electromechanical coupling equation, determined by electrical parameters and mechanical parameters, of a piezoelectric material. Modeling can be carried out according to a piezoelectric equation to obtain a calculation method between the voltage applied by the piezoelectric actuator and the pitching and yawing actuation angles of the device, so that the excitation effect of the device in the ground test process can be accurately controlled and predicted. The method is not only suitable for pitching and yawing two-degree-of-freedom actuation calculation, but also can be used for calculating the actuation angle of a three-axis degree-of-freedom experimental device added with rolling drive through coordinate transformation under the condition of adding parameters such as rolling angular velocity and the like in the face of the three-axis degree-of-freedom experimental device added with rolling drive. At present, according to a calculation method based on the device, calculation is carried out only by considering the degree of freedom of the pitching axis and the yawing axis.

Description

Technical Field

[0001] This invention belongs to the field of wind tunnel experiments in hypersonic flow field environments, and relates to a multi-degree-of-freedom high-frequency motion simulation device for aircraft dynamic stability testing and a method for calculating the motion angle. Background Technology

[0002] In the development of high-performance aircraft such as supersonic fighter jets, wind tunnel testing plays a crucial role as an indispensable key technology. By simulating the airflow environment under different flight conditions, wind tunnel testing provides vital technical support for guiding the aerodynamic layout development of aircraft. However, in high-speed flow environments, even minor attitude changes or slight airflow disturbances during flight can induce instantaneous and drastic changes in aerodynamic loads, leading to flight attitude oscillations and divergences. This makes it difficult for the control system to respond and adjust in a timely manner, seriously threatening flight stability and service safety. Therefore, dynamic stability simulation tests for supersonic and other high-performance aircraft are essential. The core of dynamic stability simulation tests is to simulate the motion state of an aircraft under disturbance using a scaled-down model to obtain key parameters such as aerodynamic loads. Simultaneously, the key data obtained from dynamic stability simulation experiments in high-speed wind tunnel environments can guide the aerodynamic layout design of aircraft, thereby improving the aircraft's extreme maneuverability and more effectively ensuring its service stability and safety. In dynamic stability simulation tests in high-speed wind tunnels, traditional experimental setups can only simulate single-degree-of-freedom motion. This not only results in low-quality simulations due to the poor adaptability of single-degree-of-freedom systems, but also necessitates frequent start-ups and shutdowns of the equipment for disassembly, assembly, and component replacement to obtain complete dynamic stability test data for the aircraft, severely impacting test efficiency and increasing costs. While current motion simulation systems designed for low-speed wind tunnel dynamic stability tests can meet the requirements for multi-degree-of-freedom motion simulation, their large size and low operating frequency make them unsuitable for the confined space of high-speed wind tunnels. Therefore, current traditional experimental setups cannot achieve multi-degree-of-freedom high-frequency motion simulation in a high-speed wind tunnel environment in a single test. Based on these problems, to meet the experimental requirements of wind tunnel testing, there is an urgent need to develop and design a multi-degree-of-freedom high-frequency motion simulation device for surface-mounted aircraft dynamic stability testing.

[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 solution of the present invention:

[0008] A multi-degree-of-freedom high-frequency motion simulation device for aircraft dynamic stability testing and a method for calculating the actuation angle are disclosed. First, a flexible spring is tightened to the front end of the excitation section. Then, a piezoelectric actuator is assembled into the cavity of the excitation section, ensuring that the unwired section of the actuator is flush against the front end of the cavity and connected to the flexible spring. Next, a movable base, a slanted concave block, and a slanted preload block are sequentially assembled at the wiring end of the piezoelectric actuator, and the slanted preload block is tightened with screws to provide axial preload force to the piezoelectric actuator, thereby reducing transmission backlash and improving the transmission accuracy of the piezoelectric actuator. Then, a cylinder and air pipe are installed into the excitation section to provide damping force for the experimental device. Finally, a bow shaft, a vibrating head, and a force balance are sequentially assembled at the head of the excitation section, and a chisel block is hammered in to securely connect the force balance and the vibrating head. The assembly of the device is now complete. The core structure of this device is a coupled resonance mechanism consisting of a piezoelectric actuator and a flexible spring. This mechanism uses the piezoelectric actuator as the excitation source to generate the actuation force, and the flexible spring as the transmission and amplification device for the actuation energy. By utilizing the resonance effect, the excitation effect is enhanced.

[0009] A multi-degree-of-freedom high-frequency motion simulation device for aircraft dynamic stability testing includes an excitation section 1, a bow shaft 2, a vibration head 3, a chisel block 4, an inclined preload block 5, a piezoelectric actuator 6, an inclined concave block 7, a movable base 8, a cylinder 9, a force balance 10, an air tube 11, and a flexible spring 12.

[0010] The excitation section 1 is a cylindrical structure with four fan-shaped cavities on its surface and two square cavities inside each. The four fan-shaped cavities are used to house the piezoelectric actuator 6, the inclined concave block 7, the movable base 8, and the inclined preload block 5. The two square cavities are used to house the cylinder 9. The side wall of the excitation section 1 has a through hole, through which the air inlet of the cylinder 9 is connected to the air pump via the air pipe 11 to provide sufficient air pressure to the cylinder 9. The front end of the excitation section 1 has an arc-shaped protrusion structure for connecting with the vibrating head 3 and the bow shaft 2. The rear end of the excitation section 1 has a cylindrical protrusion structure for fixed connection with the experimental platform.

[0011] The piezoelectric actuator 6 is assembled into the fan-shaped cavity of the excitation section 1. The movable base 8, the inclined concave block 7, and the inclined preload block 5 are sequentially assembled at one end of the wiring of the piezoelectric actuator 6 to ensure that there is no transmission backlash when the piezoelectric actuator 6 is excited in the fan-shaped cavity. The cylinder 9 is assembled into the square cavity of the excitation section 1, and the air pipe 11 is connected to the cylinder 9. The front end of the excitation section 1 is screwed to one end of the flexible spring 12 to fix the bow-shaped protrusion structure at the front end of the excitation section 1 to the bow shaft 2. After assembling and connecting the bow shaft 2 to the vibrating head 3, the other end of the flexible spring 12 is screwed and assembled to the vibrating head 3. The vibrating head 3 is fixedly connected to the force balance 10 through the chisel block 4.

[0012] A method for calculating the actuation angle of a multi-degree-of-freedom high-frequency motion simulation device for aircraft dynamic stability testing is based on the electromechanical coupling equations determined by the electrical and mechanical parameters of piezoelectric materials. According to the piezoelectric equations, a model can be developed to calculate the relationship between the voltage applied by the piezoelectric actuator and the device's actuation angles in pitch and yaw, thereby accurately controlling and predicting the excitation effect of the device during ground testing. This method is not only applicable to the calculation of pitch and yaw actuation, but also, for three-degree-of-freedom experimental devices with added roll drive, the method can calculate the actuation angle through coordinate transformation when parameters such as roll angular velocity are added. Currently, the calculation method based on this device only considers the pitch and yaw axes for calculation.

[0013] The steps are as follows:

[0014] Step 1: Calculate the strain of piezoelectric actuator 6;

[0015] It is known that a multi-degree-of-freedom high-frequency motion simulation device uses four identical piezoelectric actuators 6, and the piezoelectric actuators 6 are made of several polarized piezoelectric ceramic sheets bonded together. Given the electrical and mechanical parameters of the piezoelectric actuator material 6, 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: In response to the situation; is the elastic compliance constant of the piezoelectric ceramic sheet under constant electric field strength; For stress; The piezoelectric strain constant of a single piezoelectric ceramic sheet; The voltage applied across the piezoelectric ceramic sheet, ignoring the voltage difference across each piezoelectric ceramic sheet; The thickness of the piezoelectric ceramic sheet; The elongation of a single piezoelectric actuator 6; The cross-sectional area of ​​a single piezoelectric actuator 6; The output force of a single piezoelectric actuator 6; This refers to the number of piezoelectric ceramic sheets contained in a single piezoelectric actuator 6. The original length of the single piezoelectric actuator 6;

[0019] The second step is to calculate the actuation angle.

[0020] Take the circular plane at the end of the vibrating head 3 away from the excitation section 1 as the rigid plane for calculating the actuation angle. Construct a planar rectangular coordinate system on this rigid plane, with the center of the circular plane as the origin of the rectangular coordinate system. The x-axis direction of the rectangular coordinate system is obtained by connecting the geometric centers of the four piezoelectric actuators 6 that are distributed around each other and whose relative positions are opposite. The y-axis direction of the rectangular coordinate system is obtained by the right-hand rule.

[0021] Based on the formula for the elongation of the piezoelectric actuator 6 after coupling with the flexible spring 12, the relative rotation angle, i.e., the actuation angle, of the piezoelectric actuator 6 acting on the force balance 10 is calculated:

[0022] (3)

[0023] (4)

[0024] (5)

[0025] In the formula: The center distance of the piezoelectric actuators 6 that are located on opposite sides of the four piezoelectric actuators 6 arranged in a ring. This represents the difference in elongation of the piezoelectric actuator 6 on the opposite side in the x-axis direction. This represents the difference in elongation of the piezoelectric actuator 6 on the opposite side in the y-axis direction. The angle of deflection of the rigid plane about the y-axis; Let x be the deflection angle of the rigid plane about the x-axis; The deflection angle after the four piezoelectric actuators 6 are coupled together;

[0026] Step 3: Establish the angle-control voltage control equation;

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

[0028] (6)

[0029] In the formula: U1 and U2 are the voltages applied across the piezoelectric actuator 6 in the x-axis direction; U3 and U4 are the voltages applied across the piezoelectric actuator 6 in the y-axis direction.

[0030] The beneficial effects of this invention are as follows: This invention proposes a method for calculating the actuation angle of a multi-degree-of-freedom high-frequency motion simulation device for aircraft dynamic stability testing. It uses a piezoelectric actuator as the excitation source and achieves the transfer and amplification of actuation energy through the coupling resonance of a flexible spring. This device achieves motion simulation of pitch and yaw axes through four axially radially distributed power sources and corresponding transmission mechanisms. This overcomes the shortcomings of existing experimental devices, such as difficulties in multi-degree-of-freedom motion simulation in high-speed wind tunnels and the waste of experimental resources due to frequent disassembly and assembly, while also meeting the size limitations of experimental equipment in high-speed wind tunnel testing environments. To achieve precise control of the device, this invention performs a simple calculation of the actuation angle based on the piezoelectric equation, facilitating users to quickly write relevant control algorithms and achieve precise control of the device. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of a multi-degree-of-freedom high-frequency motion simulation device for testing the dynamic stability of aircraft.

[0032] Figure 2 This is a geometric diagram of the deflection angle calculation, where (a) is a three-dimensional projection view of the core actuator of this device, (b) is a left view of the core actuator of this device, (c) is a schematic diagram of the deflection process and deflection angle of the piezoelectric actuator, and (d) is a schematic diagram of the voltage applied to both ends of the four piezoelectric actuators.

[0033] Figure 3 This is a flowchart illustrating the calculation of the device's operating angle;

[0034] Figure 4 This is a schematic diagram of the excitation section;

[0035] In the diagram: 1-excitation section, 2-bow shaft, 3-vibration head, 4-chisel block, 5-slanted preload block, 6-piezoelectric actuator, 7-slanted concave block, 8-moving base, 9-cylinder, 10-force balance, 11-air pipe, 12-flexible spring. Detailed Implementation

[0036] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0037] Example

[0038] The center distance of the diagonal 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 for a multi-degree-of-freedom high-frequency motion simulation device for aircraft dynamic stability testing are as follows:

[0040] The flexible spring 12 is assembled to the front end of the excitation section 1. The piezoelectric actuator 6, the movable base 8, the inclined concave block 7, and the inclined preload block 5 are assembled into the fan-shaped cavity of the excitation section 1. The cylinder 9 is connected to 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 at the front of the excitation section 1. At this point, a multi-degree-of-freedom high-frequency motion simulation device for aircraft dynamic stability testing is installed.

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

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

[0043] The calculations are performed using the following parameters as an example:

[0044] The elastic compliance constant of a piezoelectric ceramic sheet at a voltage of 100V for The elastic compliance constant of the piezoelectric ceramic sheet at a voltage of 300V for The piezoelectric strain constant of a single piezoelectric ceramic sheet is... The four piezoelectric actuators 6 are connected to voltages of respectively .

[0045] Assuming the piezoelectric actuator 6 is in a mechanically free state, i.e., the output force is... Furthermore, a single piezoelectric actuator (6) contains 100 piezoelectric ceramic sheets, so the elongation of the piezoelectric actuator 6 connected to a 100V voltage is... The elongation of a single piezoelectric actuator 6, which is 6mm long and connected to a 300V voltage. It is 18mm.

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

[0047] From the above calculations, it can be seen that The diameter is 12 mm, while the measured center distance r of the diagonal piezoelectric actuator 6 is 48 mm. Referencing formula (6):

[0048]

[0049] Therefore, it can be calculated Solving for .

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

[0051] A multi-degree-of-freedom high-frequency motion simulation device for aircraft dynamic stability testing utilizes a piezoelectric actuator 6 as the excitation source and a flexible spring 12 as the actuation energy transfer and amplification device, leveraging resonance to achieve high-frequency motion simulation. Simultaneously, a cylinder 9 installed in the excitation section 1 provides damping force. This structure, capable of simultaneously simulating pitch and yaw motion along two axes, overcomes the limitation of existing experimental devices in high-speed wind tunnel environments for multi-degree-of-freedom motion simulation. Furthermore, the device's lightweight and simple structure meets the size constraints of high-speed wind tunnel testing, providing an effective solution for successful wind tunnel dynamic stability testing. The proposed actuation angle calculation method allows users to quickly and accurately control the device's motion, enabling wider engineering applications.

Claims

1. A multi-degree-of-freedom high-frequency motion simulation device for aircraft dynamic stability testing, characterized in that, The multi-degree-of-freedom high-frequency motion simulation device includes an excitation section (1), a bow shaft (2), a vibrating 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 cylinder (9), a force balance (10), an air tube (11), and a flexible spring (12). The excitation section (1) is a cylindrical structure with four fan-shaped cavities on it and two square cavities inside. Each of the four fan-shaped cavities is equipped with a piezoelectric actuator (6), a slanted concave block (7), a movable base (8), and a slanted preload block (5). The two square cavities are used to load cylinders (9). The side wall of the excitation section (1) has through holes, and the air inlet of the cylinder (9) is connected to the air pump through the air pipe (11) to provide air pressure to the cylinder (9). The front end of the excitation section (1) is provided with an arc-shaped protrusion structure for connecting with the vibrating head (3) and the bow shaft (2). The rear end of the excitation section (1) is provided with a cylindrical protrusion structure for fixed connection with the experimental platform. The piezoelectric actuator (6) is assembled into the fan-shaped cavity of the excitation section (1). The movable base (8), the inclined concave block (7) and the inclined pre-tightening block (5) are sequentially assembled at one end of the wiring 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 cylinder (9) is assembled into the square cavity of the excitation section (1), and the air pipe (11) is connected to the cylinder (9). The front end of the excitation section (1) is screwed to one end of the flexible spring (12) to fix the bow-shaped protrusion structure at the front end of the excitation section (1) to the bow shaft (2). After assembling and connecting the bow shaft (2) to the vibrating head (3), the other end of the flexible spring (12) is screwed and assembled to the vibrating head (3). The vibrating head (3) is fixedly connected to the force balance (10) through the chisel block (4).

2. The method for calculating the actuation angle using the multi-degree-of-freedom high-frequency motion simulation device as described in claim 1, characterized in that, The steps are as follows: The first step is to construct a multi-degree-of-freedom high-frequency motion simulation device; The second step is to calculate the strain of the piezoelectric actuator (6); It is known that the multi-degree-of-freedom high-frequency motion simulation device uses four identical piezoelectric actuators (6), and the piezoelectric actuators (6) used are made of several polarized piezoelectric ceramic sheets bonded together. Given the electrical and mechanical parameters of the piezoelectric actuator (6) material, according to the piezoelectric equation, the elongation obtained by a single piezoelectric actuator (6) under a given voltage is: （1） （2） In the formula: In response to the situation; is the elastic compliance constant of the piezoelectric ceramic sheet under constant electric field strength; For stress; The piezoelectric strain constant of a single piezoelectric ceramic sheet; The voltage applied across the piezoelectric ceramic sheet, ignoring the voltage difference across each piezoelectric ceramic sheet; The thickness of the piezoelectric ceramic sheet; The elongation of a single piezoelectric actuator (6); The cross-sectional area of ​​a single piezoelectric actuator (6); The output force of a single piezoelectric actuator (6); The number of piezoelectric ceramic sheets contained in a single piezoelectric actuator (6) The original length of the single piezoelectric actuator (6); Step 3: Calculate the actuation angle; Take the circular plane at the end of the vibrating head (3) away from the excitation section (1) as the rigid plane for calculating the actuation angle. Construct a planar rectangular coordinate system on this rigid plane. Take the center of the circular plane as the origin of the rectangular coordinate system. Take the geometric center of the piezoelectric actuator (6) that is located on the opposite side of the four piezoelectric actuators (6) that are distributed around it to obtain the x-axis direction of the rectangular coordinate system. According to the right-hand rule, obtain the y-axis direction of the rectangular coordinate system. Based on the elongation formula after coupling the piezoelectric actuator (6) and the flexible spring (12), the relative rotation angle, i.e. the actuation angle, of the piezoelectric actuator (6) acting on the force balance (10) is calculated: （3） （4） （5） In the formula: The center distance of the piezoelectric actuators (6) that are located on opposite sides of the four piezoelectric actuators (6) that are distributed in a ring around each other; The difference in elongation of the piezoelectric actuator (6) on the opposite side in the x-axis direction; The difference in elongation of the piezoelectric actuator (6) on the opposite side in the y-axis direction; The angle of deflection of the rigid plane about the y-axis; Let x be the deflection angle of the rigid plane about the x-axis; The deflection angle after coupling of the four piezoelectric actuators (6); Step 4: Establish the angle-control voltage control equation; Combining equations (1), (2), (3), (4), and (5), we get: （6） In the formula: U1 and U2 are the voltages applied to both ends of the piezoelectric actuator (6) in the x-axis direction; U3 and U4 are the voltages applied to both ends of the piezoelectric actuator (6) in the y-axis direction.

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