Simulation modeling method for angle sweep test of inertial navigation system

Abstract

The application discloses a simulation modeling method for angular sweep frequency test of an inertial navigation system, which is based on the principle of angular sweep frequency test, and a virtual angular sweep frequency vibration table is established. The equivalent angular motion vibration load is applied through eccentric line motion loading. After simulation, the input and output data are post-processed, the angular motion transmission (amplitude-frequency characteristic) curve of the inertial navigation system is obtained, and the simulation result provides a direct basis for evaluation and optimization of the transmission characteristic of the inertial navigation system. The application can solve the problem that the inertial navigation system cannot perform angular motion transmission characteristic simulation and effect evaluation in the design stage.

Description

Technical Field

[0001] This invention relates to the field of inertial navigation system structural design and analysis technology, and in particular to a simulation modeling method for inertial navigation system angle sweep frequency test. Background Technology

[0002] Angular motion transfer characteristics are a crucial performance indicator for inertial navigation systems (INS), significantly impacting their navigation accuracy and environmental adaptability. In recent years, as high-speed aircraft have placed increasingly stringent demands on the accuracy and environmental adaptability of INS, vibration damping and buffering designs have become essential. This, in turn, leads to amplification of the angular motion transfer curve in the low-frequency range. While filtering can mitigate the adverse effects of this amplification, excessive amplification in angular motion transfer is still insufficient for high-precision INS systems to meet performance requirements. Therefore, it is necessary to perform angular motion transfer characteristic simulations during the design phase to optimize vibration damper performance parameters, which is of significant engineering importance for improving the angular motion transfer characteristics of INS.

[0003] Previously, the evaluation of angular motion transmission characteristics of inertial navigation systems (INS) was mainly based on angular sweep frequency physical experiments. If the requirements were not met, vibration dampers with different frequencies and damping were replaced, and the experiments were repeated iteratively until the performance parameters of the vibration dampers that met the specifications were finally found. However, this method cannot directly confirm the performance parameters of vibration dampers that meet the angular motion transmission characteristics from the design stage, and it may not simultaneously meet the requirements for vibration reduction and buffering, bringing great technical risks to the development of INS. Therefore, using angular sweep frequency simulation in the design stage can assess the range of vibration damper performance parameters that meet the specifications at an early stage. At the same time, it can comprehensively consider design constraints such as vibration reduction and buffering, and finally determine the frequency and damping performance parameters of the vibration dampers through simulation optimization iteration. This is a scientific and effective means of INS structural design. Summary of the Invention

[0004] The technical problem solved by this invention is to provide a simulation modeling method for angular sweep frequency test of inertial navigation system, which solves the problem that the angular motion transmission characteristics simulation and effect evaluation of inertial navigation system cannot be performed in the design stage.

[0005] A simulation modeling method for angular sweep frequency test of inertial navigation system is proposed. Based on the principle of angular sweep frequency test, a virtual angular sweep frequency vibration table is established. The equivalent angular motion vibration load is applied by eccentric line motion loading. After the simulation is completed, the input and output data are post-processed to obtain the angular motion transmission curve of the inertial navigation system.

[0006] Furthermore, the simulation modeling specifically includes:

[0007] First, by utilizing the conversion relationship between angular velocity and linear acceleration, equivalent angular vibration input is achieved through eccentric linear vibration loading. The three-axis gyroscope of the inertial navigation system is used to sense the response in three vibration directions respectively. The angular vibration input curve is calculated by using the linear vibration information measured by two sets of linear vibration sensors pre-arranged on the angular vibration table. By analyzing the ratio curve of response to input, the angular motion transmission characteristic curve of the inertial navigation system is obtained.

[0008] Furthermore, during the simulation modeling process, virtual vibration tables for simulating pitch / roll axis tests and virtual vibration tables for simulating azimuth axis tests were established respectively. The virtual turntable was located below the inertial navigation system and a revolute joint was established between it and the ground, with only rotational degrees of freedom in the angular excitation direction. A cylindrical coordinate system was established at the center of the turntable, with the rotation direction consistent with the turntable's rotation direction. An excitation point model was established 1m away from the vibration table's rotation axis and rigidly connected to the turntable. The excitation point model constrained all degrees of freedom except for the rotation direction using the cylindrical coordinate system as the standard. Mass points were set at the angular vibration fixture position and the inertial table position of the inertial navigation system, respectively, for extracting the angular vibration response results in post-simulation processing. The mass was taken as 1g, and the inertia was taken as 1E-10Kg·m. 2 Before performing angular vibration simulation, a premodal analysis is conducted. The frequency range of the modal analysis is set to within 200Hz according to the task requirements. Using the large mass method, a rotational force based on a cylindrical coordinate system is applied at the excitation point to achieve frequency sweep loading. Simultaneously, the damper damping ratio parameter is input using the inserted command stream method, and simulation calculations are performed. The damping ratio ξ parameter is calculated from the amplification factor Q according to the following formula:

[0009]

[0010] Extract the angular displacement response curves of the combined angular vibration table and gyroscope positions in the simulation software. Obtain the amplitude-frequency transfer curve by dividing the curves, where the horizontal axis represents frequency and the vertical axis represents amplification. Perform secondary calculations on the curves in data processing software such as Origin or Excel. The calculation formula is as follows:

[0011] y = 20·lg (x)

[0012] The amplitude-frequency transfer curve with frequency on the horizontal axis and dB on the vertical axis was obtained, thus the angular motion transfer characteristics of the inertial navigation system were obtained.

[0013] This method is based on the principle of angular sweep frequency test. A virtual angular sweep frequency vibration table is established, and the equivalent angular motion vibration load is applied by eccentric line motion loading. After the simulation is completed, the input and output data are post-processed to obtain the angular motion transmission (amplitude-frequency characteristic) curve of the inertial navigation system. The simulation results provide a direct basis for the evaluation and optimization of the transmission characteristics of the inertial navigation system. Attached Figure Description

[0014] Figure 1 Schematic diagram of angular vibration test bench and sensor distribution;

[0015] a: Vibration about the pitch / roll axis b: Vibration about the azimuth axis

[0016] Figure 2 Schematic diagram of a virtual angular vibration test bench for an inertial navigation system;

[0017] Figure 3 The basic angular motion transmission characteristics of inertial navigation systems.

[0018] In the diagram: 1. Inertial navigation system; 2. Vibration damper; 3. Angular vibration fixture; 4. Angular vibration table; 5. Angular vibration exciter. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings.

[0020] Based on the principle of angle sweep frequency testing, this invention proposes a simulation modeling method for angle sweep frequency testing of inertial navigation systems:

[0021] As we know from physics, the relationship between the linear velocity V in the circular direction and the angular velocity of a moving object is: V = W·R, where R is the radius of the circle.

[0022] When R is 1m, V = W

[0023] For sinusoidal frequency sweep

[0024] That is:

[0025] This establishes the relationship between the eccentric linear acceleration A and the angular velocity W of the vibration table, thus realizing the angular velocity vibration excitation of the equivalent vibration table through linear vibration excitation.

[0026] like Figure 1 , 2As shown, based on the working principle of the angular vibration test bench (i.e., the vibration table has only one rotational degree of freedom), the equivalent angular vibration input is achieved through eccentric linear vibration loading by utilizing the conversion relationship between angular velocity and linear acceleration. The inertial navigation system's three-axis gyroscopes are used to sense the responses in three vibration directions. The angular vibration input curve is calculated using the linear vibration information measured by two sets of linear vibration sensors pre-arranged on the angular vibration bench. By analyzing the ratio curve of response to input, the angular motion transmission characteristic curve of the inertial navigation system is obtained. In the simulation modeling process, virtual vibration benches simulating the pitch / roll axis and azimuth axis are established respectively. The virtual turntable is located below the inertial navigation system, with a revolute joint established between it and the ground, possessing only rotational degrees of freedom in the angular excitation direction. A cylindrical coordinate system is established at the center of the turntable, where the Y-axis (i.e., the rotation direction) is consistent with the turntable's rotation direction. An excitation point model is established 1m away from the vibration table's rotation axis and is connected to the turntable. A rigid connection is established, and the excitation point model is constrained in cylindrical coordinates, except for the Y-axis (rotation direction). Mass points are set at the angular vibration fixture location and the inertial platform of the inertial navigation system (the structure for mounting the 3-axis gyroscope and 3-axis accelerometer) for extracting the angular vibration response results in post-simulation processing. The mass and inertia of the mass points should be very small; the mass is generally taken as 1g, and the inertia is generally taken as 1E-10Kg·m2. Before performing angular vibration simulation, a premodal analysis is performed. The frequency range of the modal analysis is determined according to the task requirements, generally focusing on the angular motion transmission characteristics in the low-frequency range, usually within 200Hz. Using the large mass method, a Y-axis (rotation direction) force based on the cylindrical coordinate system is applied at the excitation point location to achieve frequency sweep loading. At the same time, the damper damping ratio parameter is input using the inserted command stream method, and simulation calculation is performed. The damping ratio parameter ξ is calculated from the amplification factor Q according to the following formula:

[0027]

[0028] Extract the angular displacement response curves of the combined angular vibration table and gyroscope positions in the simulation software. Obtain the amplitude-frequency transfer curve by dividing the curves, where the horizontal axis represents frequency and the vertical axis represents amplification. Perform secondary calculations on the curves in data processing software such as Origin or Excel. The calculation formula is as follows:

[0029] y = 20 · lg(x)

[0030] This yields the amplitude-frequency transfer curve with frequency on the horizontal axis and dB on the vertical axis, thus obtaining the angular motion transfer characteristics of the inertial navigation system.

[0031] The above-described specific embodiments are limited to explaining and illustrating the technical solutions of the present invention, but do not constitute a limitation on the scope of protection of the claims. Those skilled in the art should understand that any new technical solutions obtained by making simple modifications or substitutions based on the technical solutions of the present invention fall within the scope of protection of the present invention.

Claims

1. A simulation modeling method for an inertial navigation system angle sweep frequency test, characterized in that, Based on the principle of angular sweep frequency testing, a virtual angular sweep frequency vibration table was established. Equivalent angular motion vibration loads were applied through eccentric linear motion loading. After simulation, the input and output data were post-processed to obtain the angular motion transmission curves of the inertial navigation system. The simulation modeling specifically includes: First, by utilizing the conversion relationship between angular velocity and linear acceleration, equivalent angular vibration input is achieved through eccentric linear vibration loading. The three-axis gyroscope of the inertial navigation system is used to sense the response in three vibration directions respectively. The angular vibration input curve is calculated by using the linear vibration information measured by two sets of linear vibration sensors pre-arranged on the angular vibration table. By analyzing the ratio curve of response to input, the angular motion transmission characteristic curve of the inertial navigation system is obtained.

2. The simulation modeling method for an inertial navigation system angle sweep frequency test according to claim 1, characterized in that, In the simulation modeling process, virtual vibration tables for simulating pitch / roll axis tests and virtual vibration tables for simulating azimuth axis tests were established. The virtual turntable was located below the inertial navigation system and a revolute joint was established between it and the ground, with only rotational degrees of freedom in the angular excitation direction. A cylindrical coordinate system was established at the center of the turntable, with the rotation direction consistent with the turntable's rotation direction. An excitation point model was established 1m away from the vibration table's rotation axis and rigidly connected to the turntable. The excitation point model constrained all degrees of freedom except for the rotation direction using the cylindrical coordinate system as the standard. Mass points were set at the angular vibration fixture position and the inertial table position of the inertial navigation system, respectively, for extracting the angular vibration response results in post-simulation processing. The mass was taken as 1g and the inertia as 1E-10Kg·m. 2 Before performing angular vibration simulation, a premodal analysis is conducted. The frequency range of the modal analysis is set to within 200Hz according to the task requirements. Using the large mass method, a rotational force based on a cylindrical coordinate system is applied at the excitation point to achieve frequency sweep loading. Simultaneously, the damper damping ratio parameter is input using an inserted command stream, and simulation calculations are performed. The parameter is obtained from the magnification factor Q according to the following formula: , Extract the angular displacement response curves of the combined angular vibration table and gyroscope positions in the simulation software. Obtain the amplitude-frequency transfer curve by dividing the curves, where the horizontal axis represents frequency and the vertical axis represents amplification. Perform secondary calculations on the curves in Origin or Excel data processing software using the following formula: We obtained the amplitude-frequency transfer curve with frequency on the horizontal axis and dB on the vertical axis, thus obtaining the angular motion transfer characteristics of the inertial navigation system.

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