Transverse vibration slope acquisition method and device for full-rocket modal test of bundled rockets

Abstract

The application discloses a kind of full rocket modal test transverse vibration slope acquisition method and device for bundled rocket, selects rocket reference point, sets reference accelerometer and reference gyro in the reference point;Select slope to be measured point, set gyroscope in the to-be-measured point;Select test modal order, apply the modal order constant frequency sinusoidal force excitation to rocket body, and excitation frequency is equivalent to the order modal frequency;According to the measurement value of the reference accelerometer, the reference gyro, the to-be-measured point gyroscope, the reference point displacement amplitude is u, the to-be-measured point angular displacement amplitude is θ, the reference point angular rate phase is φ1, and the to-be-measured point angular rate phase is φ2;Determine full rocket modal transverse vibration slope according to the phase difference Δ of to-be-measured gyro and reference gyro angular rate φ2-φ1, judge the positive and negative sign of transverse vibration slope value, Δ φ < 90 0 Then the sign is negative, Δ φ ≥ 90 0 Then the sign is positive.The application can be applied to the dynamics analysis and pitch, yaw, roll multi-channel attitude control design of bundled rocket.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of carrier rockets, in particular to a full-rocket modal test lateral vibration slope acquisition method and device for bundled rockets, which can solve the slope data acquisition problem of multiple channels of pitch and yaw under the condition of fixed-frequency excitation of bundled rockets. BACKGROUND

[0002] When developing the attitude control and flight network design of a carrier rocket, the influence of the elastic vibration of the rocket body must be considered, otherwise the rocket body may be unstable. As an important single machine in the rocket attitude control device, the slope of the rocket body obtained by processing the angular rate identified by the gyroscope plays a key role in the pitch, yaw and roll of the rocket. Therefore, in the full-rocket modal test, it is particularly important to measure the slope value at the installation position of the gyroscope.

[0003] The existing slope acquisition method is that when acquiring the slope value of the same order lateral vibration mode, it is divided into the main vibration plane and the non-main vibration plane, for example, the pitch is the main vibration plane and the yaw is the non-main vibration plane. The gyroscope in the main vibration plane can measure the value and judge the sign, and the gyroscope in the non-main vibration plane can only measure the value and cannot judge the sign. Many single-core stage rockets assume that the rocket body is a symmetrical structure during development, and only the characteristics of the main vibration plane are considered. The data of the non-main vibration plane is borrowed from the main vibration plane, and it is believed that there is only a difference in sign between the two. Such a slope acquisition method conforms to the assumption of symmetrical structure. Due to the complex modal characteristics of the new generation of solid-liquid bundled rockets, the slope values of the pitch and yaw reference planes of the same order lateral vibration mode need to be acquired respectively. Not only the numerical value of the slope value of the two reference planes is concerned, but also the sign of the slope value. SUMMARY

[0004] In order to solve the problem of acquiring the slope values of the pitch and yaw reference planes of the same order lateral vibration of the bundled rocket in the full-rocket modal test, and to solve the technical problem that in the existing test, only the slope value and sign of the main vibration plane can be acquired, and the slope value of the non-main vibration plane can only be acquired without judging the sign of the slope value, the present application provides a full-rocket modal test lateral vibration slope acquisition method and device for bundled rockets.

[0005] The present application provides a full-rocket modal test lateral vibration slope acquisition method for bundled rockets, which comprises the following steps:

[0006] S1, setting a reference accelerometer and a reference gyroscope at a reference point of the rocket, and setting a gyroscope at a to-be-measured point of the rocket;

[0007] S2, selecting a test modal order, applying a sinusoidal force excitation of the modal order to the rocket body, and selecting the excitation frequency as the modal frequency of the order;

[0008] S3, calculating the reference point displacement amplitude as u and the measured point angular displacement amplitude as θ according to the measured values of the quasi-accelerometer, the reference gyro and the measured point gyro;

[0009] S4, determining the lateral vibration slope of the whole rocket mode According to the phase difference Δφ = φ2- φ1 between the phase of the measured point gyro and the angular rate phase of the reference gyro, the positive and negative signs of the lateral vibration slope value are determined, Δφ < 90°, then the sign is negative, and Δφ ≥ 90°, then the sign is positive.

[0010] Further, the reference accelerometer is used to measure the acceleration of the reference point as the reference acceleration A;

[0011] The reference gyro is used to measure the phase of the reference point as the reference reference phase φ1 of the measured point.

[0012] The measured point gyro is used to measure the vibration angular rate value Θ and the angular rate phase φ2 of the measured point.

[0013] Further, calculating the reference point displacement amplitude u specifically includes: assuming that the vibration frequency of a certain order of the main vibration plane of the rocket body is ω, calculating the reference displacement amplitude as

[0014] Calculating the measured point angular displacement amplitude θ specifically includes: calculating the angular displacement amplitude by the vibration angular rate amplitude Θ of the measured point and the vibration frequency of a certain order of the main vibration plane ω.

[0015] Further, the reference point of the rocket is the vertex of the head of the rocket body; after the rocket discards the fairing, the reference point of the rocket is the vertex of the head of the payload.

[0016] Further, the reference gyro has multiple reference gyros, at least one reference gyro sensitive axis of which is arranged on the rocket pitch plane, at least one reference gyro sensitive axis of which is arranged on the rocket yaw plane, and at least one reference gyro sensitive axis of which is arranged on the rocket roll axis.

[0017] Further, the measured point has multiple measured points, and the gyro sensitive axes of a part of the measured points are arranged on the rocket pitch plane and the gyro sensitive axes of a part of the measured points are arranged on the rocket yaw plane.

[0018] Further, the measured point is arranged at the inter-stage connection position, the inter-tank connection position and / or the storage tank of the rocket.

[0019] Further, the rocket body is excited by the modal order constant frequency sinusoidal force, and the amplitude and phase of the excitation remain stable.

[0020] Further, the method further comprises: for the bundled rocket, the rocket body keeps the steady resonance, a point on a non-main vibration plane of the rocket body is selected as a rocket reference point, a reference accelerometer and a reference gyroscope are arranged at the reference point, and steps S3-S4 are repeated.

[0021] The application further provides a transverse vibration slope acquisition device for a full-rocket modal test of a bundled rocket.

[0022] The excitation application module applies the modal order constant frequency sinusoidal force to the rocket body, and the excitation frequency is equal to the modal frequency of the order;

[0023] The parameter calculation module calculates the reference point displacement amplitude u, the measured point angular displacement amplitude θ, the reference point angular rate phase φ1 and the measured point angular rate phase φ2 according to the measurement values of the reference accelerometer, the reference gyroscope and the measured gyroscope.

[0024] The slope calculation module determines the full-rocket modal transverse vibration slope According to the phase difference Δφ = φ2-φ1 of the angular rates of the measured gyroscope and the reference gyroscope, the sign of the transverse vibration slope value is determined, and when Δφ < 90°, the sign is negative, and when Δφ ≥ 90°, the sign is positive.

[0025] The application can meet the condition of constant frequency excitation, and can simultaneously collect the slope values of the pitch and yaw reference directions and determine the signs of the slopes at the positions, and solves the problem that only the sign of the slope in one of the pitch and yaw reference planes is determined in the prior art. The application has important significance for bundled rockets with complex modal characteristics, including symmetric four-assisted boost or face-symmetric double-assisted boost bundled rockets. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a diagram of a reference measurement point and a slope value measured position of the bundled rocket according to the application;

[0027] Figure 2 is a diagram of the sensitive axis direction of the gyroscope of the reference gyroscope and the measured position according to the application;

[0028] Figure 3 is an implementation flowchart of the transverse vibration slope acquisition method for the full-rocket modal test of the bundled rocket according to the application;

[0029] Figure 4 is a slope value measured by a traditional method;

[0030] ​​Figure 5 The slope value measured for the method of the application. DETAILED DESCRIPTION

[0031] The specific embodiment of the application is described in detail below in conjunction with the accompanying drawings. In order to measure the lateral vibration slope data of the two reference planes of pitch and yaw and determine the sign of the slope, the application proposes a lateral vibration slope acquisition method and device for full rocket modal test of bundled rockets.

[0032] The lateral vibration slope acquisition method for full rocket modal test of bundled rockets of the application comprises:

[0033] S1, a rocket reference point is selected, a reference accelerometer and a reference gyroscope are arranged at the reference point, a slope to-be-measured point is selected, and a gyroscope is arranged at the to-be-measured point. The reference accelerometer is used to measure the acceleration of the reference point as a reference acceleration A; the reference gyroscope is used to measure the phase of the reference point as a reference reference phase φ1 of the to-be-measured point; and the to-be-measured point gyroscope is used to measure the vibration angular rate value Θ and the angular rate phase φ2 of the to-be-measured point. Figure 1 is a schematic diagram of the reference measurement point and the slope value to-be-measured position on the bundled rocket. According to the rocket modal simulation prediction result and the attitude control design result, the possible installation positions of the pitch and yaw rate gyroscopes are determined. For the carrier rocket, the gyroscope is generally not installed on the inner wall of the tank. In addition, in order to reduce the aerodynamic resistance, the outer wall of the cabin section is also not selected as much as possible. As long as the slope value of the position meets the flight control stability requirement and is convenient to install, the position can be selected.

[0034] As shown in Figure 1 , the positions of the No. 3 measurement point to the No. 8 measurement point in the interstage section are all optional positions of the gyroscope. The positions of the reference accelerometer and the reference gyroscope are generally selected to be positions at which the local vibration is small but the overall vibration mode is obvious. The reference vibration mode obtained by integrating the acceleration measured by the reference accelerometer is used as the normalized vibration mode reference point, and the phase of the reference gyroscope is used as the reference phase of the to-be-measured position. The sign of the slope value can be determined according to the phase difference. In the embodiment, it can be assumed that the pitch plane in Figure 2 is the main vibration plane.

[0035] Figure 1 In , the No. 1 point and the No. 2 point respectively represent two reference gyroscopes, the reference accelerometer and the reference gyroscope are at the same position, the sensitive axis of the No. 1 reference gyroscope is arranged in the rocket pitch plane, the sensitive axis of the No. 2 reference gyroscope is arranged in the rocket yaw plane, and the slope value is normalized by the translational component of the vibration mode obtained by integrating the reference accelerometer. The No. 3 to No. 8 measurement points represent the to-be-measured positions of the slope value, the No. 3 to No. 5 measurement points represent that the sensitive axes of the gyroscopes are in the rocket pitch plane, and the No. 6 to No. 8 measurement points represent that the sensitive axes of the gyroscopes are in the yaw plane. Figure 2Indicate the sensitive axis direction of each gyroscope, in one embodiment, the sensitive axis direction of the 1st reference gyroscope of the rocket head is consistent with the sensitive axis direction of the to-be-tested gyroscope 3, 4, 5, and the sensitive axis direction of the 2nd reference gyroscope of the rocket head is consistent with the sensitive axis direction of the to-be-tested gyroscope 6, 7, 8. By using the method of the present application, the slope values and signs of the main vibration plane and the non-main vibration plane have practical significance. The to-be-tested point can be arranged at the inter-stage connection position, the inter-tank connection position and / or the storage tank.

[0036] S2, select the test modal order, apply a constant frequency sinusoidal force excitation to the rocket body, and the excitation frequency is equal to the modal frequency of the order.

[0037] The full rocket modal test will undergo multiple sinusoidal excitation force sweeps, and the amplitude and phase of the excitation force will be adjusted to ensure that the pitch, yaw and roll plane modes can be fully reflected in the frequency response function, and abnormal and unimportant modes are excluded. The modal orders that have greater influence on the attitude control design are determined and recorded in combination with the pre-test analysis results. Before the formal start of the full rocket modal test, the modal characteristics of the rocket body will be analyzed in advance based on the simulation calculation model, and the calculation results have reference significance for the full rocket modal test.

[0038] Among the selected modal orders, the slope collection is carried out step by step, for example, the first order modal of the main vibration plane is implemented by constant frequency sinusoidal force excitation. If multiple exciters are used, the phases of the constant frequency sinusoidal forces applied by all the exciters participating in the excitation are ensured to be in phase or anti-phase, and the excitation frequency is the same as the rocket body frequency. The constant frequency excitation force must ensure that the amplitude of the force is constant and the phase is stable, the rocket body reaches steady-state resonance, and each measuring point exhibits single degree of freedom vibration characteristics. Under the premise of stable amplitude and phase, slope collection can be carried out.

[0039] S3, according to the measurement values of the reference accelerometer, the reference gyroscope and the to-be-tested point gyroscope, the reference point displacement amplitude is u, the to-be-tested point angular displacement amplitude is θ, the reference point angular rate phase is φ1, and the to-be-tested point angular rate phase is φ2.

[0040] Under the constant frequency force excitation, each point of the rocket body exhibits single degree of freedom vibration. Assuming that the vibration frequency of the first order of the main vibration plane is ω, at this time, the acceleration amplitude of the reference position 1st gyroscope sensitive axis direction is A, the accelerometer is an electrical element, and the direct measurement value is voltage. After sensitivity conversion, the amplitude physical quantity A is obtained. After integration of the acceleration, the reference displacement amplitude is The angular rate phase measured by the 1st reference gyroscope is φ1, the angular rate amplitude measured by the to-be-tested point 3rd gyroscope is a voltage value, the angular rate amplitude physical quantity Θ is obtained through gyroscope sensitivity conversion, and the angular displacement amplitude is obtained after integration. The angular rate phase measured by the 3rd gyroscope is φ2, and the phase difference with the 1st reference gyroscope is Δφ = φ2- φ1.

[0041] S4. Determine the transverse vibration slope of the entire rocket mode. Based on the phase difference Δφ = φ2 - φ1 between the angular velocities of the gyroscope under test and the reference gyroscope, determine the sign of the transverse vibration slope value; if Δφ < 90°, then... If the sign is negative, then Δφ≥90° The sign is positive.

[0042] Since the final step is to obtain slope data, it is normalized according to the reference displacement and calculated using the slope formula. Obtain the normalized slope data of gyroscope No. 3 Based on the phase difference between the gyroscope under test and the reference gyroscope, determine the sign of the slope data; when Δφ < 90° If the sign is negative, then Δφ≥90° The sign is positive. Traditional methods can simultaneously measure normalized slope data from non-dominant plane gyroscopes. However, because the sensitive axis direction of the non-dominant plane gyroscope is inconsistent with the reference gyroscope, the sign cannot be determined. Traditional methods are the slope acquisition methods used in single-core rockets, as shown in the attached diagram. Figure 4 .

[0043] Steps S3 and S4 can be automated by developing a slope acquisition system. The slope values ​​and signs at the positions of gyroscopes 3, 4, and 5, as well as the slope values ​​at the positions of gyroscopes 6, 7, and 8, are obtained synchronously. However, since the sensitive axis directions of gyroscopes 6, 7, and 8 are inconsistent with those of reference gyroscope 1, gyroscopes 6, 7, and 8 cannot determine their signs.

[0044] S5, keeping the reference accelerometer unchanged, that is, ensuring the reference displacement used for normalization remains unchanged, and keeping the rocket body in a steady-state resonance state, reselect reference gyroscope No. 2, and repeat steps 4 and 5 to obtain the slope values ​​and signs of gyroscopes No. 6, 7, and 8, as shown in the appendix. Figure 5 The entire process of this invention does not require shutting down or restarting the exciter, because if the exciter is restarted, the rocket body needs time to re-reach the resonance state for tuning. Therefore, avoiding restarting the exciter helps improve the efficiency of the test.

[0045] Furthermore, the slope acquisition system and the acceleration signal acquisition system need to be started simultaneously and work together to complete the task.

[0046] This completes the acquisition of lateral vibration slope data for the pitch and yaw references of the full-rocket modal test of the bundled rocket.

[0047] Appendix Figure 4The results without step 6 are shown in the table, the reference gyro is No. 1 gyro, the sensitive axis directions of No. 3, No. 4 and No. 5 gyro are consistent with No. 1 gyro, the obtained slope values are meaningful in both value and sign, the sensitive axes of No. 6, No. 7 and No. 8 gyro are inconsistent with No. 1 gyro, the obtained slope values are meaningful in value but not in sign. Figure 5 The double-channel lateral vibration slope acquisition method realized by the application is shown in the table, step 6 is added, the reference gyro of No. 6, No. 7 and No. 8 gyro is changed to No. 2 reference gyro which is consistent with the sensitive axis direction of the gyro, the values and signs are both meaningful.

[0048] The application provides a full-rocket modal test lateral vibration slope acquisition device for bundled rockets, which comprises:

[0049] The excitation applying module applies a modal order fixed-frequency sinusoidal force excitation to the rocket body according to the selected test modal order, and the excitation frequency is equal to the modal frequency of the order.

[0050] The parameter calculation module calculates the reference point displacement amplitude u, the measured point angular displacement amplitude θ, the reference point angular rate phase φ1 and the measured point angular rate phase φ2 according to the measurement values of the reference accelerometer, the reference gyro and the measured gyro.

[0051] The slope calculation module determines the full-rocket modal lateral vibration slope According to the phase difference Δφ = φ2-φ1 of the angular rates of the measured gyro and the reference gyro, the positive and negative signs of the lateral vibration slope value are determined, if Δφ < 90°, the sign is negative, and if Δφ ≥ 90°, the sign is positive.

[0052] Although the application has been disclosed with the above preferred embodiments, it is not intended to limit the application, and any person skilled in the art can make possible changes and modifications to the technical solutions of the application by using the disclosed methods and technical contents without departing from the spirit and scope of the application, therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the application without departing from the technical solutions of the application are within the protection scope of the application.​​

Claims

1. A method for acquiring the lateral vibration slope in a full-rocket modal test of a strapped rocket, characterized in that, include: S1. Set up a reference accelerometer and a reference gyroscope at the rocket reference point; A gyroscope is installed at the test point on the rocket. S2. Select the test mode order, and apply the modal order constant frequency sinusoidal force to the rocket body to excite it. The excitation frequency is selected from the modal frequency of this order. S3. Based on the measured values ​​of the reference accelerometer, the reference gyroscope, and the gyroscope at the point under test, calculate the displacement amplitude of the reference point as u, the angular displacement amplitude of the point under test as θ, the angular rate phase of the reference point as φ1, and the angular rate phase of the point under test as φ2; wherein φ1 is used as the reference reference phase of the point under test. S4. Determine the transverse vibration slope of the entire rocket mode. Based on the phase difference Δφ = φ2 - φ1 between the phase of the angular rate at the test point of the gyroscope and the phase of the angular rate at the reference point of the reference gyroscope, determine the sign of the transverse vibration slope value. If Δφ < 90°, then... If the sign is negative, then Δφ≥90° The sign is positive; The rocket reference point is the apex of the rocket's nose cone; after the rocket jettisons its fairing, the rocket reference point is the apex of the payload's nose cone. There are multiple reference gyroscopes, of which at least one reference gyroscope sensing axis is set on the rocket pitch plane, at least one reference gyroscope sensing axis is set on the rocket yaw plane, and at least one reference gyroscope sensing axis is set on the rocket roll axis. There are multiple test points. The sensitive axes of the gyroscopes at some of the test points are set in the rocket pitch plane, and the sensitive axes of the gyroscopes at some of the test points are set in the rocket yaw plane. The rocket pitch plane is set as the principal vibration plane, and the rocket yaw plane is set as the non-principal vibration plane. Further steps include: for a bundled rocket, the rocket body maintains steady-state resonance, a point on the non-dominant plane of the rocket body is selected as the rocket reference point, a reference accelerometer and a reference gyroscope are set at the reference point, and steps S3-S4 are repeated.

2. The method according to claim 1, characterized in that, The reference accelerometer is used to measure the acceleration of the reference point as the reference acceleration A; The reference gyroscope is used to measure the angular rate phase φ1 of the reference point; The gyroscope at the test point is used to measure the amplitude of the vibration angular rate Θ and the phase of the angular rate φ2 at the test point.

3. The method according to claim 2, characterized in that, Calculating the displacement amplitude of the reference point, u, specifically includes: assuming the vibration frequency of a certain order of the principal vibration plane of the rocket body is ω, calculating the displacement amplitude of the reference point as u. Calculating the angular displacement amplitude θ of the point to be measured specifically includes: calculating the angular displacement amplitude of the point to be measured using the vibration angular velocity amplitude Θ of the point to be measured and the vibration frequency ω of a certain order of the principal vibration plane.

4. The method according to claim 1, characterized in that, The test points are located at the connection points between rocket stages, between tanks, and / or in storage tanks.

5. The method according to claim 4, characterized in that, The modal-order constant-frequency sinusoidal force is applied to the rocket body to excite it, and the excitation amplitude and phase remain stable.

6. A data acquisition device for acquiring the lateral vibration slope of a full-rocket modal test of a strapped rocket, based on any one of claims 1 to 5, characterized in that, include: The excitation application module selects the test mode order and applies a constant-frequency sinusoidal force to the rocket body to excite the rocket body. The excitation frequency is equal to the mode frequency of that order. The parameter calculation module calculates the displacement amplitude of the reference point as u, the angular displacement amplitude of the point under test as θ, the angular rate phase of the reference point as φ1, and the angular rate phase of the point under test as φ2, based on the measured values ​​of the reference accelerometer, the reference gyroscope, and the gyroscope of the point under test; φ1 is used as the reference phase of the point under test. The slope calculation module determines the transverse vibration slope of the entire rocket mode. Based on the phase difference Δφ = φ2 - φ1 between the angular velocities of the gyroscope under test and the reference gyroscope, determine the sign of the transverse vibration slope value; if Δφ < 90°, then... If the sign is negative, then Δφ≥90° The sign is positive.

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