Design method and system for cut-off frequency of rocket attitude control system
By actively designing the cutoff frequency of the rocket attitude control system based on the mission, obtaining the dominant frequency of attitude angular velocity and combining it with the rocket body frequency constraints, the problem of the lack of universality in the design of the existing technology is solved, and the theoretical and economic selection of the cutoff frequency is realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-30
- Publication Date
- 2026-04-14
AI Technical Summary
The design of cutoff frequencies for existing rocket attitude control systems lacks a systematic approach and relies heavily on empirical formulas, resulting in designs that lack universality and theoretical basis and cannot adapt to different rocket engine jet control mechanisms.
By actively designing based on the mission, the nominal trajectory, guidance maneuver attitude angle, and disturbance attitude angular velocity of the rocket are obtained. After superposition, a Fourier transform is performed to obtain the dominant frequency. The cutoff frequency is adjusted in combination with the elastic vibration and liquid sloshing frequency of the rocket body to ensure amplitude and phase margin constraints.
The theoretical and general design of the cutoff frequency of the rocket attitude control system has been realized, enabling the selection of the optimal solution within the theoretical range and saving costs.
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Figure CN121857754A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of aerospace technology, and in particular to a design method and system for the cutoff frequency of a rocket attitude control system. Background Technology
[0002] The cutoff frequency of a rocket attitude control system is a key indicator reflecting the maneuverability of the rocket attitude control system in the rocket design scheme. It is closely related to the bandwidth of the rocket attitude control system and reflects the speed and ability of the rocket attitude control system to respond to commands and suppress interference.
[0003] Currently, there is no systematic method for designing cutoff frequencies; instead, it is mostly designed based on empirical formulas and then manually adjusted. A common design method involves fixing various coefficients along the rocket's nominal trajectory at the point of maximum dynamic pressure or the moment of maximum aerodynamic torque, assuming the rocket's attitude control system is stable. These coefficients are derived from parameters such as aerodynamic derivatives, mass, and inertia. Then, the parameters of the PD controller for the rocket's attitude control system are calculated using the following formula (i.e., in the formula below). and The PD controller is a proportional-derivative controller used for rocket attitude and flight trajectory control.
[0004] When designing the rocket attitude control system, At the moment of maximum aerodynamic torque coefficient, according to A preliminary selection is made within the range of 2.5 to 3, that is: The value should be determined within the range of 2.5 to 3. in, This represents the gain coefficient of the main loop of the roll channel. This represents the aerodynamic damping coefficient of the roll channel. This represents the inertial coupling coefficient of the roll channel.
[0005] It can be obtained from the following formula
[0006]
[0007] in, ξ is the time constant of the roll channel, and ξ is the attitude motion damping coefficient, which can be selected in the range of 0.5 to 0.8. The initial value determines The computational basis, and Through ξ and The binding process ultimately formed a design chain of "aerodynamic characteristics → gain parameters → dynamic response".
[0008] It can be obtained from the following formula
[0009]
[0010] in, This represents the gain coefficient of the roll channel damping term.
[0011] The parameters of the PD controller in the rocket attitude control system can directly affect the cutoff frequency f. c1 Therefore, after obtaining the parameters of the PD controller for the rocket attitude control system, adjustments were made based on the requirement that the low-frequency amplitude margin of the rocket attitude control system be greater than 12dB, and the cutoff frequency f was fixed at this moment. c1 As a standard.
[0012] However, this method is largely based on experience, especially The selection of values within the range of 2.5 to 3 is generally only applicable to rocket engine swivel spray control mechanisms and is neither universal nor theoretically sound.
[0013] Therefore, how to make the design of the cutoff frequency of the rocket attitude control system break away from the design method based on experience and reference to similar models, and make the design of the cutoff frequency theoretical and universal, is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention
[0014] This application provides a design method and system for the cutoff frequency of a rocket attitude control system, which can actively design the cutoff frequency according to the mission, making the design of the cutoff frequency both theoretical and universal.
[0015] To solve the above-mentioned technical problems, this application provides the following technical solution:
[0016] A method for designing the cutoff frequency of a rocket attitude control system includes the following steps: Step S110: During the rocket scheme demonstration stage, the nominal trajectory of the rocket is designed according to the mission requirements, and the nominal trajectory attitude angle is obtained. The nominal trajectory attitude angular velocity is obtained based on the nominal trajectory attitude angle; Step S120: The guidance maneuver attitude angle is obtained based on the correction of the rocket's center of mass motion deviation by the rocket guidance circuit. The guidance maneuver attitude angular velocity is obtained based on the guidance maneuver attitude angle; Step S130: The disturbance attitude angle caused by interference factors is obtained. The disturbance attitude angular velocity is obtained based on the disturbance attitude angle; Step S140: The nominal trajectory attitude angular velocity is... The attitude angular velocity is obtained by superimposing the attitude angular velocity of the guided maneuver and the attitude angular velocity of the disturbance. The amplitude-frequency characteristic curve of the attitude angular velocity is obtained based on the attitude angular velocity, and the dominant frequency of the attitude angular velocity is obtained from the amplitude-frequency characteristic curve. Step S150: Determine the rigid body attitude control frequency according to the dominant frequency of the attitude angular velocity, and determine the initial value of the cutoff frequency of the rocket attitude control system according to the rigid body attitude control frequency. Step S160: Adjust the initial value of the cutoff frequency according to the elastic vibration frequency and liquid sloshing frequency of the rocket body, and determine the final value of the cutoff frequency based on the adjusted value of the cutoff frequency in combination with the amplitude margin / phase margin constraint.
[0017] In the design method of the cutoff frequency of the rocket attitude control system as described above, preferably, the nominal ballistic attitude angle is differentiated with respect to the control period to obtain the nominal ballistic attitude angular velocity, the guided maneuver attitude angle is differentiated with respect to the control period to obtain the guided maneuver attitude angular velocity, and the disturbed attitude angle is differentiated with respect to the control period to obtain the disturbed attitude angular velocity.
[0018] The design method for the cutoff frequency of the rocket attitude control system described above preferably involves performing a Fourier transform or a fast Fourier transform on the attitude angular velocity to obtain the amplitude-frequency characteristic curve of the attitude angular velocity, wherein the peak frequency point of the amplitude-frequency characteristic curve is the dominant frequency of the attitude angular velocity.
[0019] The design method for the cutoff frequency of the rocket attitude control system described above, preferably, is based on f ctrl ≥(1.2~2)f d Determine the rigid body attitude control frequency f ctrl The lower limit value, according to f c1 ≥(1~2)f ctrl Determine the cutoff frequency f of the rocket attitude control system c1 The initial value of f, where f d The dominant frequency of attitude angular velocity.
[0020] The design method for the cutoff frequency of the rocket attitude control system described above preferably ensures that the cutoff frequency f c1 The adjustment value is related to the elastic vibration frequency f of the arrow body. elastic Liquid sloshing frequency fslosh The intervals meet the requirement of 2 to 10 times.
[0021] A design system for the cutoff frequency of a rocket attitude control system includes: an angular velocity acquisition unit, an angular velocity superposition unit, a dominant frequency acquisition unit, and a cutoff frequency determination unit. The angular velocity acquisition unit designs the rocket's nominal trajectory and obtains the nominal trajectory attitude angles based on mission requirements during the rocket feasibility study phase, and then obtains the nominal trajectory attitude angular velocity based on these angles. The angular velocity acquisition unit obtains the guided maneuver attitude angles based on the correction of the rocket's center of mass motion deviation by the rocket guidance loop, and then obtains the guided maneuver attitude angular velocity based on these angles. The angular velocity acquisition unit acquires the disturbance attitude angles caused by interference factors, and then obtains the disturbance attitude angular velocity based on these angles. The angular velocity superposition unit... The nominal ballistic attitude angular velocity, the guided maneuver attitude angular velocity, and the disturbed attitude angular velocity are superimposed to obtain the attitude angular velocity. The dominant frequency acquisition unit obtains the amplitude-frequency characteristic curve of the attitude angular velocity based on the attitude angular velocity, and obtains the dominant frequency of the attitude angular velocity from the amplitude-frequency characteristic curve. The cutoff frequency determination unit determines the rigid body attitude control frequency according to the dominant frequency of the attitude angular velocity, and determines the initial value of the cutoff frequency of the rocket attitude control system according to the rigid body attitude control frequency. The cutoff frequency determination unit adjusts the initial value of the cutoff frequency according to the elastic vibration frequency and liquid sloshing frequency of the rocket body, and determines the final value of the cutoff frequency based on the adjusted value of the cutoff frequency, combined with the amplitude margin / phase margin constraints.
[0022] The design system for the cutoff frequency of the rocket attitude control system described above preferably involves differentiating the nominal ballistic attitude angle with respect to the control period to obtain the nominal ballistic attitude angular velocity, differentiating the guided maneuver attitude angle with respect to the control period to obtain the guided maneuver attitude angular velocity, and differentiating the disturbed attitude angle with respect to the control period to obtain the disturbed attitude angular velocity.
[0023] The design system for the cutoff frequency of the rocket attitude control system described above preferably involves performing a Fourier transform or a fast Fourier transform on the attitude angular velocity to obtain the amplitude-frequency characteristic curve of the attitude angular velocity, wherein the peak frequency point of the amplitude-frequency characteristic curve is the dominant frequency of the attitude angular velocity.
[0024] The design system for the cutoff frequency of the rocket attitude control system described above, preferably, is based on f ctrl ≥(1.2~2)f d Determine the rigid body attitude control frequency f ctrl The lower limit value, according to f c1 ≥(1~2)f ctrl Determine the cutoff frequency f of the rocket attitude control system c1 The initial value of f, where f d The dominant frequency of attitude angular velocity.
[0025] The design system for the cutoff frequency of the rocket attitude control system described above preferably ensures that the cutoff frequency f c1 The adjustment value is related to the elastic vibration frequency f of the arrow body. elastic Liquid sloshing frequency f slosh The intervals meet the requirement of 2 to 10 times.
[0026] Compared to the aforementioned background technology, the rocket attitude control system cutoff frequency design method and system in this application can actively design the cutoff frequency according to the mission, making the cutoff frequency design theoretical and universal, breaking away from the past design methods based on experience and reference to similar models, thereby allowing the selection of the most suitable scheme (such as the power size when selecting a servo) within the theoretical range, saving costs. Attached Figure Description
[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings.
[0028] Figure 1 This is a flowchart of the design method for the cutoff frequency of the rocket attitude control system provided in this application;
[0029] Figure 2 This is a schematic diagram of the design system for the cutoff frequency of the rocket attitude control system provided in this application. Detailed Implementation
[0030] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.
[0031] Example 1
[0032] like Figure 1 As shown, this application provides a design method for the cutoff frequency of a rocket attitude control system, including the following steps:
[0033] Step S110, Rocket scheme demonstration stage: Design the rocket's nominal trajectory and obtain the nominal trajectory attitude angle according to the mission requirements, and obtain the nominal trajectory attitude angular velocity based on the nominal trajectory attitude angle.
[0034] In the design of rocket attitude control systems, the frequency characteristics of attitude angular velocity are the core basis for determining the cutoff frequency of the rocket attitude control system. During rocket flight, the change in attitude angle includes three parts: the nominal ballistic attitude angle, the guidance maneuver attitude angle generated by the guidance loop, and the disturbance attitude angle generated by various disturbances.
[0035] During the rocket design and feasibility study phase, the rocket's nominal trajectory is designed based on mission requirements, which means the nominal trajectory attitude angle θ is known. ballistic (t), nominal ballistic attitude angle θ ballistic (t) is a low-frequency signal that varies smoothly with the flight time sequence, representing the nominal ballistic attitude angle θ. ballistic The nominal ballistic attitude angular velocity is obtained by differentiating (t) with respect to the control period.
[0036] Step S120: Obtain the guidance maneuver attitude angle based on the correction of the rocket's center of mass motion deviation by the rocket guidance circuit, and obtain the guidance maneuver attitude angular velocity based on the guidance maneuver attitude angle.
[0037] The core function of a rocket's guidance circuit is to correct deviations in the rocket's center of mass motion (e.g., range deviation, orbital altitude deviation). During this correction process, it outputs the guidance maneuver attitude angle θ. guidance (t), guidance maneuver attitude angle θ guidance (t) represents the nominal ballistic attitude angle θ. ballistic The correction amount is the sum of the baseline value and the adjustment amount, which will affect the guided maneuver attitude angle θ. guidance (t) The derivative of the control period yields the guided maneuver attitude angular velocity.
[0038] Based on the control capabilities of the rocket's attitude control system actuators, the engine (or servo) trim angle and the guidance maneuver attitude angle θ of the rocket under specific flight conditions are obtained. guidance (t) Take the value as 10% of the trim angle. For example: the trim angle is 5°, the guided maneuver attitude angle is 0.5°, the control period is 10ms, and the guided maneuver attitude angular velocity is 0.5 / 0.01=50° / s=0.87rad / s.
[0039] Step S130: Obtain the disturbance attitude angle caused by the interference factors, and obtain the disturbance attitude angular velocity based on the disturbance attitude angle;
[0040] During flight, rockets experience disturbances in their attitude angle θ due to factors such as structural interference, aerodynamic interference, wind interference, and engine interference. disturbance (t), the perturbation attitude angle θ disturbance (t) The derivative with respect to the control period yields the disturbance attitude angular velocity.
[0041] Step S140: Superimpose the nominal ballistic attitude angular velocity, the guided maneuver attitude angular velocity, and the disturbed attitude angular velocity to obtain the attitude angular velocity. Obtain the amplitude-frequency characteristic curve of the attitude angular velocity based on the attitude angular velocity, and obtain the dominant frequency of the attitude angular velocity from the amplitude-frequency characteristic curve.
[0042] The nominal ballistic attitude angular velocity ω ballistic (t), guided maneuver attitude angular velocity ω guidance (t) and the perturbation attitude angular velocity ω disturbance The attitude angular velocity ω(t) can be obtained by directly superimposing the values of ω(t). ballistic (t)+ω guidance (t)+ω disturbance Then, perform a Fourier transform or fast Fourier transform on the attitude angular velocity ω(t) to obtain the amplitude-frequency response curve of the attitude angular velocity. The peak frequency of this amplitude-frequency response curve is the dominant frequency f of the attitude angular velocity. d .
[0043] Step S150: Determine the rigid body attitude control frequency according to the dominant frequency of the attitude angular velocity, and determine the initial value of the cutoff frequency of the rocket attitude control system according to the rigid body attitude control frequency.
[0044] The cutoff frequency of the rocket attitude control system determines its "tracking capability" for signals—only when the rigid body attitude control frequency f is constant can the rocket's attitude control system achieve its tracking capability. ctrl The dominant frequency f above the controlled attitude angular velocity d Only then can the rocket attitude control system complete the closed-loop process of detection, calculation, and execution within one cycle of signal change, thus avoiding the accumulation of attitude deviations.
[0045] To ensure sufficient tracking margin, this application follows f ctrl ≥(1.2~2)f d Determine the rigid body attitude control frequency f ctrl The lower limit value, according to f c1 ≥(1~2)f ctrl Determine the cutoff frequency f of the rocket attitude control system c1 The initial value.
[0046] Step S160: Adjust the initial value of the cutoff frequency according to the elastic vibration frequency of the rocket body and the sloshing frequency of the liquid. Combine the amplitude margin / phase margin constraints and determine the final value of the cutoff frequency based on the adjusted value of the cutoff frequency.
[0047] The design of a rocket attitude control system needs to avoid modal coupling and ensure flight stability in order to solve the problem of mutual interference between rigid body control and flexible modes. Therefore, it is necessary to test and obtain the elastic vibration frequency f of the rocket body. elastic and the frequency of liquid sloshing f sloshAdjust the cutoff frequency f c1 The initial value ensures the cutoff frequency f c1 The adjustment value is related to the elastic vibration frequency f of the arrow body. elastic Liquid sloshing frequency f slosh The spacing should meet the requirement of 2 to 10 times to avoid modal coupling.
[0048] Then, combined with gain margin / phase margin constraints (e.g., gain margin > 12dB, phase margin > 45°), at the cutoff frequency f c1 Based on the adjustment values, the final cutoff frequency f of the rocket attitude control system was determined. c1 The final value.
[0049] Example 2
[0050] like Figure 2 As shown, this application provides a design system 200 for the cutoff frequency of a rocket attitude control system, including: an angular velocity acquisition unit 210, an angular velocity superposition unit 220, a dominant frequency acquisition unit 230, and a cutoff frequency determination unit 240.
[0051] During the rocket program demonstration phase, the angular velocity acquisition unit 210 designs the rocket's nominal trajectory and obtains the nominal trajectory attitude angle based on the mission requirements, and obtains the nominal trajectory attitude angular velocity based on the nominal trajectory attitude angle.
[0052] In the design of rocket attitude control systems, the frequency characteristics of attitude angular velocity are the core basis for determining the cutoff frequency of the rocket attitude control system. During rocket flight, the change in attitude angle includes three parts: the nominal ballistic attitude angle, the guidance maneuver attitude angle generated by the guidance loop, and the disturbance attitude angle generated by various disturbances.
[0053] During the rocket design and feasibility study phase, the rocket's nominal trajectory is designed based on mission requirements, which means the nominal trajectory attitude angle θ is known. ballistic (t), nominal ballistic attitude angle θ ballistic (t) is a low-frequency signal that varies smoothly with the flight time sequence, representing the nominal ballistic attitude angle θ. ballistic The nominal ballistic attitude angular velocity is obtained by differentiating (t) with respect to the control period.
[0054] The angular velocity acquisition unit 210 obtains the guided maneuver attitude angle based on the correction of the rocket's center of mass motion deviation by the rocket guidance circuit, and obtains the guided maneuver attitude angular velocity based on the guided maneuver attitude angle.
[0055] The core function of a rocket's guidance circuit is to correct deviations in the rocket's center of mass motion (e.g., range deviation, orbital altitude deviation). During this correction process, it outputs the guidance maneuver attitude angle θ. guidance (t), guidance maneuver attitude angle θ guidance(t) represents the nominal ballistic attitude angle θ. ballistic The correction amount of (t) is the superposition of the reference value and the adjustment amount, which will affect the guided maneuver attitude angle θ. guidance (t) The derivative of the control period yields the guided maneuver attitude angular velocity.
[0056] Based on the control capabilities of the rocket's attitude control system actuators, the engine (or servo) trim angle and the guidance maneuver attitude angle θ of the rocket under specific flight conditions are obtained. guidance (t) Take the value as 10% of the trim angle. For example: the trim angle is 5°, the guided maneuver attitude angle is 0.5°, the control period is 10ms, and the guided maneuver attitude angular velocity is 0.5 / 0.01=50° / s=0.87rad / s.
[0057] The angular velocity acquisition unit 210 acquires the disturbance attitude angle caused by the interference factors, and obtains the disturbance attitude angular velocity based on the disturbance attitude angle.
[0058] During flight, rockets experience disturbances in their attitude angle θ due to factors such as structural interference, aerodynamic interference, wind interference, and engine interference. disturbance (t), the perturbation attitude angle θ disturbance (t) The derivative with respect to the control period yields the disturbance attitude angular velocity.
[0059] The angular velocity superposition unit 220 superimposes the nominal ballistic attitude angular velocity, the guided maneuver attitude angular velocity, and the disturbance attitude angular velocity to obtain the attitude angular velocity. The dominant frequency acquisition unit 230 obtains the amplitude-frequency characteristic curve of the attitude angular velocity based on the attitude angular velocity, and obtains the dominant frequency of the attitude angular velocity from the amplitude-frequency characteristic curve.
[0060] The nominal ballistic attitude angular velocity ω ballistic (t), guided maneuver attitude angular velocity ω guidance (t) and the perturbation attitude angular velocity ω disturbance The attitude angular velocity ω(t) can be obtained by directly superimposing the values of ω(t). ballistic (t)+ω guidance (t)+ω disturbance Then, perform a Fourier transform or fast Fourier transform on the attitude angular velocity ω(t) to obtain the amplitude-frequency response curve of the attitude angular velocity. The peak frequency of this amplitude-frequency response curve is the dominant frequency f of the attitude angular velocity. d .
[0061] The cutoff frequency determination unit 240 determines the rigid body attitude control frequency according to the dominant frequency of the attitude angular velocity, and determines the initial value of the cutoff frequency of the rocket attitude control system according to the rigid body attitude control frequency.
[0062] The cutoff frequency of the rocket attitude control system determines its "tracking capability" for signals—only when the rigid body attitude control frequency f is constant can the rocket's attitude control system achieve its tracking capability. ctrl The dominant frequency f above the controlled attitude angular velocity d Only then can the rocket attitude control system complete the closed-loop process of detection, calculation, and execution within one cycle of signal change, thus avoiding the accumulation of attitude deviations.
[0063] To ensure sufficient tracking margin, this application follows f ctrl ≥(1.2~2)f d Determine the rigid body attitude control frequency f ctrl The lower limit value, according to f c1 ≥(1~2)f ctrl Determine the cutoff frequency f of the rocket attitude control system c1 The initial value.
[0064] The cutoff frequency determination unit 240 adjusts the initial value of the cutoff frequency based on the elastic vibration frequency of the rocket body and the sloshing frequency of the liquid, and determines the final value of the cutoff frequency based on the adjusted value of the cutoff frequency in combination with the amplitude margin / phase margin constraints.
[0065] The design of a rocket attitude control system needs to avoid modal coupling and ensure flight stability in order to solve the problem of mutual interference between rigid body control and flexible modes. Therefore, it is necessary to test and obtain the elastic vibration frequency f of the rocket body. elastic and the frequency of liquid sloshing f slosh Adjust the cutoff frequency f c1 The initial value ensures the cutoff frequency f c1 The adjustment value is related to the elastic vibration frequency f of the arrow body. elastic Liquid sloshing frequency f slosh The spacing should meet the requirement of 2 to 10 times to avoid modal coupling.
[0066] Then, combined with gain margin / phase margin constraints (e.g., gain margin > 12dB, phase margin > 45°), at the cutoff frequency f c1 Based on the adjustment values, the final cutoff frequency f of the rocket attitude control system was determined. c1 The final value.
[0067] The design method and system for the cutoff frequency of the rocket attitude control system in this application can actively design the cutoff frequency according to the mission, making the cutoff frequency design theoretical and universal, breaking away from the past design methods based on experience and reference to similar models. Thus, the most suitable solution (such as the power size when selecting a servo) can be selected within the theoretical range, saving costs.
[0068] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.
[0069] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A method for designing the cutoff frequency of a rocket attitude control system, characterized in that, Includes the following steps: Step S110, Rocket scheme demonstration stage: Design the rocket's nominal trajectory and obtain the nominal trajectory attitude angle according to the mission requirements, and obtain the nominal trajectory attitude angular velocity based on the nominal trajectory attitude angle. Step S120: Obtain the guidance maneuver attitude angle based on the correction of the rocket's center of mass motion deviation by the rocket guidance circuit, and obtain the guidance maneuver attitude angular velocity based on the guidance maneuver attitude angle. Step S130: Obtain the disturbance attitude angle caused by the interference factors, and obtain the disturbance attitude angular velocity based on the disturbance attitude angle; Step S140: Superimpose the nominal ballistic attitude angular velocity, the guided maneuver attitude angular velocity, and the disturbed attitude angular velocity to obtain the attitude angular velocity. Obtain the amplitude-frequency characteristic curve of the attitude angular velocity based on the attitude angular velocity, and obtain the dominant frequency of the attitude angular velocity from the amplitude-frequency characteristic curve. Step S150: Determine the rigid body attitude control frequency according to the dominant frequency of the attitude angular velocity, and determine the initial value of the cutoff frequency of the rocket attitude control system according to the rigid body attitude control frequency. Step S160: Adjust the initial value of the cutoff frequency according to the elastic vibration frequency and liquid sloshing frequency of the rocket body, and determine the final value of the cutoff frequency based on the adjusted value of the cutoff frequency, combined with the amplitude margin / phase margin constraint.
2. The design method for the cutoff frequency of the rocket attitude control system according to claim 1, characterized in that, The nominal ballistic attitude angle is differentiated with respect to the control period to obtain the nominal ballistic attitude angular velocity; the guided maneuver attitude angle is differentiated with respect to the control period to obtain the guided maneuver attitude angular velocity; and the disturbed attitude angle is differentiated with respect to the control period to obtain the disturbed attitude angular velocity.
3. The design method for the cutoff frequency of the rocket attitude control system according to claim 1 or 2, characterized in that, Perform a Fourier transform or a fast Fourier transform on the attitude angular velocity to obtain the amplitude-frequency characteristic curve of the attitude angular velocity. The peak frequency point of the amplitude-frequency characteristic curve is the dominant frequency of the attitude angular velocity.
4. The design method for the cutoff frequency of the rocket attitude control system according to claim 1 or 2, characterized in that, According to f ctrl ≥(1.2~2)f d Determine the rigid body attitude control frequency f ctrl The lower limit value, according to f c1 ≥(1~2)f ctrl Determine the cutoff frequency f of the rocket attitude control system c1 The initial value of f, where f d The dominant frequency of attitude angular velocity.
5. The design method for the cutoff frequency of the rocket attitude control system according to claim 4, characterized in that, Ensure the cutoff frequency f c1 The adjustment value is related to the elastic vibration frequency f of the arrow body. elastic Liquid sloshing frequency f slosh The intervals meet the requirement of 2 to 10 times.
6. A design system for the cutoff frequency of a rocket attitude control system, characterized in that, include: Angular velocity acquisition unit, angular velocity superposition unit, dominant frequency acquisition unit, and cutoff frequency determination unit; During the rocket program demonstration phase, the angular velocity acquisition unit designs the rocket's nominal trajectory and obtains the nominal trajectory attitude angles based on the mission requirements, and then obtains the nominal trajectory attitude angular velocity based on the nominal trajectory attitude angles. The angular velocity acquisition unit obtains the guided maneuver attitude angle based on the correction of the rocket's center of mass motion deviation by the rocket guidance circuit, and obtains the guided maneuver attitude angular velocity based on the guided maneuver attitude angle. The angular velocity acquisition unit acquires the disturbance attitude angle caused by interference factors, and obtains the disturbance attitude angular velocity based on the disturbance attitude angle; The angular velocity superposition unit superimposes the nominal ballistic attitude angular velocity, the guided maneuver attitude angular velocity, and the disturbed attitude angular velocity to obtain the attitude angular velocity. The dominant frequency acquisition unit obtains the amplitude-frequency characteristic curve of the attitude angular velocity based on the attitude angular velocity, and obtains the dominant frequency of the attitude angular velocity from the amplitude-frequency characteristic curve. The cutoff frequency determination unit determines the rigid body attitude control frequency according to the dominant frequency of the attitude angular velocity, and determines the initial value of the cutoff frequency of the rocket attitude control system according to the rigid body attitude control frequency. The cutoff frequency determination unit adjusts the initial value of the cutoff frequency based on the elastic vibration frequency of the rocket body and the sloshing frequency of the liquid. Combined with the amplitude margin / phase margin constraints, the final value of the cutoff frequency is determined based on the adjusted value of the cutoff frequency.
7. The design system for the cutoff frequency of the rocket attitude control system according to claim 6, characterized in that, The nominal ballistic attitude angle is differentiated with respect to the control period to obtain the nominal ballistic attitude angular velocity; the guided maneuver attitude angle is differentiated with respect to the control period to obtain the guided maneuver attitude angular velocity; and the disturbed attitude angle is differentiated with respect to the control period to obtain the disturbed attitude angular velocity.
8. The design system for the cutoff frequency of the rocket attitude control system according to claim 6 or 7, characterized in that, Perform a Fourier transform or a fast Fourier transform on the attitude angular velocity to obtain the amplitude-frequency characteristic curve of the attitude angular velocity. The peak frequency point of the amplitude-frequency characteristic curve is the dominant frequency of the attitude angular velocity.
9. The design system for the cutoff frequency of the rocket attitude control system according to claim 6 or 7, characterized in that, According to f ctrl ≥(1.2~2)f d Determine the rigid body attitude control frequency f ctrl The lower limit value, according to f c1 ≥(1~2)f ctrl Determine the cutoff frequency f of the rocket attitude control system c1 The initial value of f, where f d The dominant frequency of attitude angular velocity.
10. The design system for the cutoff frequency of the rocket attitude control system according to claim 9, characterized in that, Ensure the cutoff frequency f c1 The adjustment value is related to the elastic vibration frequency f of the arrow body. elastic Liquid sloshing frequency f slosh The intervals meet the requirement of 2 to 10 times.