Vibration error distribution and suppression method for airborne suspension type light beam pointing mechanism

Abstract

The invention discloses a vibration error distribution and suppression method for an airborne suspension type light beam pointing mechanism, and belongs to the technical field of photoelectric detection. The method comprises the following steps: determining a shearing frequency range of a servo system; a broadband vibration excitation light beam pointing mechanism is adopted to judge whether requirements are met or not; a broadband vibration excitation light beam pointing mechanism is adopted, and a frequency point where resonance occurs and the amplification factor of the corresponding resonance point are recorded; a fixed-frequency vibration excitation light beam pointing mechanism is adopted, the optical axis jitter amount generated by each frequency point where resonance occurs is obtained, and sorting is carried out according to the optical axis jitter amount; the servo system is in an open-loop state, the light beam pointing mechanism is excited again, the optical axis jitter amount generated by each frequency point where resonance occurs is obtained, and sorting is carried out according to the optical axis jitter amount; comparing the difference between the two optical axis jitter amounts, and determining the reason of the optical axis jitter; and the vibration error of the light beam pointing mechanism is compensated. The precision of the suspension type light beam pointing mechanism is effectively improved, and the detection capability of photoelectric products is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of photoelectric detection, and in particular relates to a vibration error distribution and suppression method for an airborne suspended light beam pointing mechanism. Background Art

[0002] The main feature of the airborne optoelectronic pod is that it adopts a standard mounting structure, which allows it to flexibly mount payloads suitable for various tasks without changing the structure of the carrier and the hardware interface. The airborne optoelectronic pod has a large aspect ratio. The carrier vibration load and aerodynamic load transmitted through the pylon are complex vibration conditions with high vibration intensity and long duration. Usually, vertical vibration and lateral vibration are large, and the pod generally has an axisymmetric structure, so only vertical vibration can be considered. The main task of the airborne suspended beam pointing mechanism is to isolate the carrier base and aerodynamic disturbances to ensure that the optical axis is stably pointed in the inertial space. However, with the improvement of optoelectronic payload performance, higher requirements are placed on the beam pointing mechanism.

[0003] The traditional airborne suspended beam pointing mechanism uses multiple optical elements arranged in a large-scale geometric manner in space, which brings obvious vibration problems. It is difficult for multiple optical elements to maintain consistent phases in a vibration environment. In the actual system, the suspended beam pointing mechanism can be regarded as an elastic body with multiple degrees of freedom. The system model obtained by theoretical modeling is only an abstraction of the internal mechanism and cannot accurately reflect all the characteristics of the system. The finite element simulation method of the numerical model has large errors, especially the estimation deviation of the resonance peak of the natural frequency point during random vibration, which makes it difficult to effectively improve the accuracy of the beam pointing mechanism.

[0004] Therefore, the present invention proposes a method for allocating and suppressing vibration errors of an airborne suspended beam pointing mechanism. Summary of the invention

[0005] Technical issues to be solved:

[0006] In order to avoid the shortcomings of the prior art, the present invention provides a method for allocating and suppressing vibration errors of an airborne suspended beam pointing mechanism, which comprehensively analyzes the overall vibration response of each optical element in the airborne suspended beam pointing mechanism, the vibration phase deviation between each optical element, and the error distribution in different frequency bands, and processes and compensates them separately in combination with the bandwidth design requirements of the beam pointing mechanism servo system, thereby obtaining a high-quality beam pointing effect.

[0007] The technical solution of the present invention is: a method for allocating and suppressing vibration errors of an airborne suspended beam pointing mechanism, wherein the beam pointing mechanism is controlled by a servo system, receives feedback signals from sensors through the servo system, and adjusts the position and direction of the beam pointing mechanism in real time to ensure that the beam can accurately point to a target; the specific steps are as follows:

[0008] Determine the shear frequency range of the servo system according to the performance requirements of the beam pointing mechanism;

[0009] The beam pointing mechanism is stimulated by broadband vibration, the jitter amount in two directions of the optical axis in the imaging picture is obtained, the total jitter amount is calculated and compared with the error threshold, and when the total jitter amount is less than or equal to the error threshold, the requirement is met; when the total jitter amount is greater than the error threshold, the following steps are continued;

[0010] The beam pointing mechanism is stimulated by broadband vibration, and the response of the beam pointing mechanism is measured by an acceleration sensor, and the frequency point where resonance occurs and the magnification of the corresponding resonance point are recorded;

[0011] The beam pointing mechanism is stimulated by a fixed-frequency vibration method, the optical axis jitter generated by each resonant frequency point is obtained, and the optical axis jitters are sorted according to the magnitude of the optical axis jitters;

[0012] The servo system is placed in an open-loop state, and the beam pointing mechanism is stimulated again to obtain the optical axis jitter amount generated at each resonant frequency point, and the optical axis jitter amounts are sorted according to the magnitude of the optical axis jitter amount;

[0013] Compare the differences between the two optical axis jitters. When the difference in the optical axis jitter is greater than the set jitter threshold, it is determined that the cause of the optical axis jitter is insufficient stability margin of the servo system; when the difference in the optical axis jitter is less than or equal to the set jitter threshold, it is determined that the cause of the optical axis jitter is that a certain optical element of the beam pointing mechanism has greater elasticity and the entire platform has one or more larger resonance peaks.

[0014] Based on the determined cause of the optical axis jitter, the vibration error of the beam pointing mechanism is compensated;

[0015] Repeat the above steps until the beam pointing performance in the vibration environment meets the requirements.

[0016] A further technical solution of the present invention is: the shear frequency ω c The conditions to be determined are to ensure that the working frequency of the beam pointing mechanism is ω k The open-loop frequency characteristic amplitude at is greater than or equal to the output angle θ max With the maximum error e max The ratio of |G(jω k )|≥θ max / e max ; Simultaneous shear frequency ω c The phase margin at is between 40° and 60°.

[0017] A further technical solution of the present invention is: the jitter amounts of the optical axis in the imaging picture in two directions are Δx and Δy respectively, and the recording time should be more than 1 minute; the formula of the total jitter amount Δ of the optical axis is as follows:

[0018]

[0019] In the formula, i represents the number of samples taken during the recording time, and n represents the total number of samples taken during the recording time;

[0020] Set the error threshold to e max , when Δ≤e max When, the requirements are met.

[0021] A further technical solution of the present invention is that the frequency points where resonance occurs are recorded as f1, f2, ..., f n , the magnification of the corresponding resonance point is recorded as A1, A2, ..., A n .

[0022] A further technical solution of the present invention is that when the beam pointing mechanism is excited by a fixed frequency vibration, in a non-open loop state, the optical axis jitter amount generated at each resonant frequency point is Δ a1 , Δ a2 ,…,Δ an ; In the open loop state, the optical axis jitter generated by each resonant frequency point is Δ b1 , Δ b2 ,…,Δ bn ; The difference between the two optical axis jitters is Δ a1 -Δ b1 , Δ a2 -Δ b2 ,…,Δ an -Δ bn .

[0023] A further technical solution of the present invention is: the jitter threshold is

[0024] A further technical solution of the present invention is: the method for compensating the vibration error of the beam pointing mechanism is:

[0025] When it is determined that the cause of the optical axis jitter is insufficient stability margin of the servo system, compensation is performed by adjusting the control parameters;

[0026] When it is determined that the cause of the optical axis jitter is that a certain optical element of the beam pointing mechanism has a large elasticity, the optical element is reinforced to increase the rigidity for compensation;

[0027] When it is determined that the cause of the optical axis jitter is that the entire platform has one or more large resonance peaks, compensation is performed by adding dampers or vibration absorbers to weaken the resonance peaks;

[0028] The above three measures can be implemented separately or in combination.

[0029] A further technical solution of the present invention is: when the compensation is performed by adjusting the control parameters, a differential correction network is used. Wherein, T represents the time constant; s represents the Laplace operator; α represents the adjustment coefficient;

[0030] α<1, adjust the coefficient α to reduce it from 1 to an appropriate level, and increase the stability margin of the servo system.

[0031] A further technical solution of the present invention is: the vibration absorber is composed of a spring-damper-mass block, and adjusting the spring and the mass block can adjust the resonance point frequency and the amplification factor until the optical axis jitter of the light beam pointing mechanism at the resonance point is attenuated to less than the error threshold.

[0032] An airborne suspended beam pointing mechanism vibration error distribution and suppression system, comprising a beam pointing mechanism, an excitation module, a stability margin adjustment module, and a vibration absorber;

[0033] Apply broadband vibration or fixed-frequency vibration to the beam pointing mechanism through the excitation module, record the frequency point where resonance occurs and the magnification of the corresponding resonance point, and obtain the optical axis jitter generated by each frequency point where resonance occurs;

[0034] The control parameters are adjusted through the stability margin adjustment module to compensate for the insufficient stability margin;

[0035] The resonance peak is weakened by the vibration absorber to compensate for the larger resonance peak.

[0036] Beneficial Effects

[0037] The beneficial effects of the present invention are as follows: a method for distributing and suppressing vibration errors of an airborne suspended beam pointing mechanism of the present invention distributes and sorts vibration responses on the basis of an existing beam pointing mechanism, analyzes the frequencies that have a significant impact on beam pointing, and supplements damping links or vibration absorbers, thereby being able to specifically suppress beam jitter caused by phase differences in frequency responses of optical elements, effectively improving the accuracy of the suspended beam pointing mechanism, and improving the detection capability of optoelectronic products.

[0038] The method of the present invention unifies the vibration transmission, error distribution, pointing accuracy control and vibration response compensation of the suspended pointing mechanism of the airborne pod, adopts multiple measures, and distributes the vibration response errors of different frequency bands on the basis of not making a significant change to the overall structure. Based on the accuracy requirement of the servo system, the three frequency bands are divided into low frequency band, medium frequency band and high frequency band. The low frequency band is optimized and reinforced with parts, the medium frequency band is increased with a damping ratio or a vibration absorber is used to reduce the resonance peak, and the high frequency band is reduced to achieve vibration response error compensation, so as to obtain a high-quality light beam pointing control effect, improve the dynamic performance of the optical axis pointing of the airborne pod, and have broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The vibration error transmission distribution diagram of the suspended beam pointing mechanism is listed.

[0040] Figure 2 The relationship diagram between the servo system and resonance is listed.

[0041] Figure 3 List the compensation links and resonance improvement diagram.

[0042] Explanation of reference numerals: 1. bracket, 2. beam pointing mechanism, 3. target, 4. optical element, 5. vibration absorber, 6. photoelectric load mounting surface, 7. damper. DETAILED DESCRIPTION

[0043] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0044] Based on the existing technology, the system model obtained by theoretical modeling is only an abstraction of the internal mechanism and cannot accurately reflect all the characteristics of the system. The finite element simulation method of the numerical model has large errors, especially the estimation deviation of the resonance peak of the natural frequency point during random vibration is large, and it is difficult to effectively improve the accuracy of the beam pointing mechanism. The present invention uses the existing experimental means and data processing methods to perform vibration excitation on the distribution characteristics of the beam pointing mechanism, confirm the distribution of the pointing stiffness of the suspended beam pointing mechanism under the vibration environment with the frequency, identify the frequency band and optical elements that have a significant impact on the beam pointing, and reinforce individual optical elements in the low-frequency area, increase damping in the mid-frequency area to reduce the resonance peak, and reduce vibration or add vibration absorbers in the high-frequency area without affecting the closed-loop stability of the servo system. The phase difference between the optical elements in the pointing mechanism is reduced, thereby reducing the jitter of the optical axis and improving the beam pointing accuracy. The beam pointing mechanism is controlled by a servo system, receives the feedback signal of the sensor through the servo system, and adjusts the position and direction of the beam pointing mechanism in real time to ensure that the beam can accurately point to the target; the specific operations are as follows:

[0045] 1) Distribution of vibration error of beam pointing mechanism. In the low frequency band (generally less than 0.1ω c ) is mainly linear vibration. The responses of the optical elements in the mechanism are basically consistent, and there will be no obvious phase difference. The error in detecting long-distance targets can be ignored. A certain number of resonance peaks will be generated in the medium and high frequency bands, which will begin to affect the stability of the servo system. The resonance peaks allowed cannot exceed the relative stability margin requirements of the servo system.

[0046] 2) Determination of the influence of vibration on the optical axis pointing. Apply vibration excitation to the beam pointing mechanism and observe the optical axis jitter. The test adopts broadband vibration or fixed frequency vibration.

[0047] 3) Determine the impact of resonance on the servo system. It is necessary to determine which kind of impact resonance has on the servo system: first, a system with a low stability margin is prone to instability when vibrating; second, a higher resonance peak will make some frequency responses extremely large, and the increased interference will cause the system accuracy to drop sharply and exceed the linear region. By changing the vibration excitation value and observing the response value of the servo system at the resonance point, it can be distinguished whether the servo system has resonated or has been significantly disturbed.

[0048] 4) Compensation for the optical axis pointing error during vibration. If a problem occurs in the low-frequency band, it should be caused by looseness or low installation stiffness of individual optical components, and reinforcement compensation is sufficient; when resonance occurs in the mid-frequency band, the peak value of the resonance point should be measured. When the resonance peak is low, the servo system parameters should be adjusted appropriately to enhance the stability margin. When the resonance peak is high, the damping or vibration absorber at the resonance point should be appropriately increased to turn the narrow peak into a wide peak; when resonance occurs in the high-frequency region, vibration reduction measures should be used to reduce the damage of high-frequency vibration to components. Since it is easy to make judgments and supplements when resonance occurs in the high-frequency region, the technical solution of the present invention mainly makes judgments and supplements for the low-frequency and mid-frequency bands.

[0049] Based on the above analysis, the specific steps of the vibration error distribution and suppression method of an airborne suspended beam pointing mechanism of the present invention are as follows:

[0050] Step 1: Determine the shear frequency range of the servo system according to the performance requirements of the beam pointing mechanism;

[0051] Step 2: Use broadband vibration to stimulate the beam pointing mechanism, obtain the jitter in two directions of the optical axis in the imaging picture, calculate the total jitter and compare it with the error threshold. When the total jitter is less than or equal to the error threshold, the requirement is met; when the total jitter is greater than the error threshold, continue with the following steps;

[0052] Step 3: Use broadband vibration to excite the beam pointing mechanism, and use an acceleration sensor to measure the response of the beam pointing mechanism, and record the frequency point where resonance occurs and the magnification of the corresponding resonance point;

[0053] Step 4: Use a fixed-frequency vibration method to excite the beam pointing mechanism, obtain the optical axis jitter generated by each resonant frequency point, and sort them according to the size of the optical axis jitter;

[0054] Step 5: Place the servo system in an open-loop state, stimulate the beam pointing mechanism again, obtain the optical axis jitter generated by each resonant frequency point, and sort them according to the size of the optical axis jitter;

[0055] Step 6: Compare the differences between the two optical axis jitters. When the difference in the optical axis jitter is greater than the set jitter threshold, it is determined that the cause of the optical axis jitter is insufficient stability margin of the servo system; when the difference in the optical axis jitter is less than or equal to the set jitter threshold, it is determined that the cause of the optical axis jitter is that a certain optical element of the beam pointing mechanism has greater elasticity, or the entire platform has one or more larger resonance peaks.

[0056] Step 7: Based on the determined cause of the optical axis jitter, the vibration error of the beam pointing mechanism is compensated;

[0057] Step 8: Repeat the above steps until the beam pointing performance in the vibration environment meets the requirements.

[0058] The present invention discloses an airborne suspended beam pointing mechanism vibration error distribution and suppression system, comprising a beam pointing mechanism, an excitation module, a stability margin adjustment module, and a vibration absorber; broadband vibration or fixed-frequency vibration is applied to the beam pointing mechanism by the excitation module, the frequency point where resonance occurs and the magnification of the corresponding resonance point are recorded, and the optical axis jitter generated by each frequency point where resonance occurs is obtained; control parameters are adjusted by the stability margin adjustment module to compensate for insufficient stability margin; and the resonance peak is weakened by the vibration absorber to compensate for a larger resonance peak.

[0059] According to the requirements of the accuracy of the beam pointing mechanism, the amplitude-phase-frequency characteristics of the servo system are determined, and then the degree of resonance that the mechanism can tolerate is clarified. The modal excitation of each optical element of the beam pointing mechanism is used to obtain the vibration error-frequency distribution, and then damping or vibration absorbers are added to compensate for the natural frequency and its resonance peak. This method can effectively improve the optical axis jitter of the suspended beam pointing mechanism.

[0060] The above technical solution is further described below in conjunction with the accompanying drawings:

[0061] Reference Figure 1 As shown in the figure, the vibration error of the suspended beam pointing mechanism can be approximated as an elastic body composed of multiple mass blocks, damping and springs. Each optical component can be used as a small elastic body. The light beam enters the image plane after being reflected or transmitted by each optical unit. With the beam propagation direction as the axis, the elastic body formed by each optical element of the beam pointing mechanism will contribute to the influence of the optical axis pointing accuracy.

[0062] Reference Figure 2 As shown, the servo system bandwidth that meets the precise pointing performance requirements is determined. c The left side belongs to the low-frequency area (generally less than 0.1ω c), which can suppress the disturbance caused by vibration to a considerable extent. In general, in the low-frequency region, the multiple optical elements that constitute the beam pointing mechanism can be approximated as rigid bodies. The amplitude and phase deviation of the vibration response between the optical elements are extremely small, and no obvious angular motion will be generated, and the effect on the optical axis is minimal; the shear frequency ω c The vicinity belongs to the mid-frequency band (generally 0.1ω c ~5ω c Within), the size of the resonance peak affects the relative stability of the servo system; in the high frequency area (generally 5ω c The vibration amplitude is relatively small, and the main consideration is the impact of vibration on the reliability of components.

[0063] Reference Figure 3 As shown, it illustrates the compensation effect on the resonance point and resonance peak after adding damping or vibration absorber.

[0064] For airborne suspended beam pointing mechanisms, vibration error distribution and compensation are relatively complex. The specific implementation steps are as follows:

[0065] The first step is to determine the servo system shear frequency (ω) according to the performance requirements of the beam pointing mechanism. c ) range. The selection of shear frequency should ensure accurate pointing mechanism working frequency ω k The open-loop frequency characteristic amplitude at is greater than the output angle θ max With the maximum error e max The ratio of |G(jω k )|≥θ max / e max , while the shear frequency ω c The phase margin at is between 40° and 60°.

[0066] The second step is to use broadband vibration to excite the beam pointing mechanism and observe the jitter Δx and Δy of the optical axis in the imaging image in both directions. The recording time should be more than 1 minute, and the total jitter Δ of the optical axis should not be greater than the error e max ,Right now In the formula, i represents the number of samples taken during the recording time, and n represents the total number of samples taken during the recording time. If the requirements are met, the following steps are not performed; if the requirements are not met, proceed to the next step.

[0067] In the third step, the broadband vibration excitation beam is directed to the mechanism, and the acceleration sensor is used to measure the structural response and record the frequency points where resonance occurs (f1, f2, ..., f n ) and the magnification of the corresponding resonance point (A1, A2, ..., A n ).

[0068] The fourth step is to vibrate the beam pointing mechanism at a fixed frequency, and observe and record the optical axis jitter (Δ a1 , Δ a2 ,…,Δ an ), sort by the magnitude of the optical axis jitter;

[0069] Step 5: Put the servo system in an open-loop state (under the premise of ensuring the safety of the mechanism), stimulate again, observe and record the optical axis jitter (Δ b1 , Δ b2 ,…,Δ bn ), sort by the magnitude of the optical axis jitter;

[0070] Step 6: Compare the difference in optical axis jitter between Step 4 and Step 5, (Δ a1 -Δ b1 ), (Δ a2 -Δ b2 ),…,(Δ an -Δ bn ), to analyze the cause of optical axis jitter: If the jitter difference is greater than It can be considered that the main reason for the optical axis jitter is the insufficient stability margin of the servo system; otherwise, it may include one or two of the following reasons: a certain optical element has greater elasticity, and the entire platform has one or more larger resonance peaks.

[0071] Step 7: If the servo system stability margin is insufficient, the control parameters can be adjusted to compensate. A differential correction network can be used. Wherein, T represents the time constant; s represents the Laplace operator; α represents the adjustment coefficient; α<1, adjusting the coefficient α to reduce it from 1 to an appropriate level can increase the stability margin of the servo system; if a certain optical element has large elasticity, the structural parts can be reinforced to increase the rigidity; if the entire platform has several large resonance peaks, a vibration absorber needs to be added to weaken the resonance peak. The vibration absorber is composed of a spring-damper-mass block. Adjusting the spring and the mass block can adjust the resonance point (f1, f2, ..., f n ) frequency and magnification (A1, A2, ..., A n ), until the optical axis jitter of the beam pointing mechanism at the resonance point is attenuated to an acceptable error, and one or more vibration absorbers can be added for the resonance points with significant influence. The three measures can be implemented separately or in combination, and the second to sixth steps are repeated until the beam pointing performance meets the requirements under the vibration environment.

[0072] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A method for allocating and suppressing vibration errors of an airborne suspended beam pointing mechanism, wherein the beam pointing mechanism is controlled by a servo system, receives feedback signals from a sensor through the servo system, and adjusts the position and direction of the beam pointing mechanism in real time to ensure that the beam can accurately point to a target; characterized in that The specific steps are as follows: Determine the shear frequency range of the servo system according to the performance requirements of the beam pointing mechanism; The beam pointing mechanism is stimulated by broadband vibration, the jitter amount in two directions of the optical axis in the imaging picture is obtained, the total jitter amount is calculated and compared with the error threshold, and when the total jitter amount is less than or equal to the error threshold, the requirement is met; when the total jitter amount is greater than the error threshold, the following steps are continued; The beam pointing mechanism is stimulated by broadband vibration, and the response of the beam pointing mechanism is measured by an acceleration sensor, and the frequency point where resonance occurs and the magnification of the corresponding resonance point are recorded; The beam pointing mechanism is stimulated by a fixed-frequency vibration method, the optical axis jitter generated by each resonant frequency point is obtained, and the optical axis jitters are sorted according to the magnitude of the optical axis jitters; The servo system is placed in an open-loop state, and the beam pointing mechanism is stimulated again to obtain the optical axis jitter amount generated at each resonant frequency point, and the optical axis jitter amounts are sorted according to the magnitude of the optical axis jitter amount; Compare the differences between the two optical axis jitters. When the difference in the optical axis jitter is greater than the set jitter threshold, it is determined that the cause of the optical axis jitter is insufficient stability margin of the servo system; when the difference in the optical axis jitter is less than or equal to the set jitter threshold, it is determined that the cause of the optical axis jitter is that a certain optical element of the beam pointing mechanism has greater elasticity and the entire platform has one or more larger resonance peaks. Based on the determined cause of the optical axis jitter, the vibration error of the beam pointing mechanism is compensated; Repeat the above steps until the beam pointing performance in the vibration environment meets the requirements.

2. According to claim 1, a method for allocating and suppressing vibration errors of an airborne suspended beam pointing mechanism is characterized in that: The shear frequency ω c The conditions to be determined are to ensure that the working frequency of the beam pointing mechanism is ω k The open-loop frequency characteristic amplitude at is greater than or equal to the output angle θ max With the maximum error e max The ratio of |G(jω k )|≥θ max / e max ; Simultaneous shear frequency ω c The phase margin at is between 40° and 60°.

3. The method for allocating and suppressing vibration errors of an airborne suspended beam pointing mechanism according to claim 2, characterized in that: The jitter amounts of the optical axis in the imaging image in two directions are Δx and Δy respectively, and the recording time should be more than 1 minute; the formula of the total jitter amount Δ of the optical axis is as follows: In the formula, i represents the number of samples taken during the recording time, and n represents the total number of samples taken during the recording time; Set the error threshold to e max , when Δ≤e max When, the requirements are met.

4. The method for allocating and suppressing vibration errors of an airborne suspended beam pointing mechanism according to claim 3, characterized in that: The frequency points where resonance occurs are recorded as f1, f2, ..., f n , the magnification of the corresponding resonance point is recorded as A1, A2, ..., A n .

5. The method for allocating and suppressing vibration errors of an airborne suspended beam pointing mechanism according to claim 4, characterized in that: When the beam pointing mechanism is excited by constant frequency vibration, in the non-open loop state, the optical axis jitter generated at each resonant frequency point is Δ a1 , Δ a2 ,…,Δ an ; In the open loop state, the optical axis jitter generated by each resonant frequency point is Δ b1 , Δ b2 ,…,Δ bn ; The difference between the two optical axis jitters is Δ a1 -Δ b1 , Δ a2 -Δ b2 ,…,Δ an -Δ bn .

6. The method for allocating and suppressing vibration errors of an airborne suspended beam pointing mechanism according to claim 5, characterized in that: The jitter threshold is 7. The method for allocating and suppressing vibration errors of an airborne suspended beam pointing mechanism according to claim 6, characterized in that: The method for compensating the vibration error of the beam pointing mechanism is: When it is determined that the cause of the optical axis jitter is insufficient stability margin of the servo system, compensation is performed by adjusting the control parameters; When it is determined that the cause of the optical axis jitter is that a certain optical element of the beam pointing mechanism has a large elasticity, the optical element is reinforced to increase the rigidity for compensation; When it is determined that the cause of the optical axis jitter is that the entire platform has one or more large resonance peaks, compensation is performed by adding dampers or vibration absorbers to weaken the resonance peaks; The above three measures can be implemented separately or in combination.

8. The method for allocating and suppressing vibration errors of an airborne suspended beam pointing mechanism according to claim 7, characterized in that: When the compensation is performed by adjusting the control parameters, a differential correction network is used. Wherein, T represents the time constant; s represents the Laplace operator; α represents the adjustment coefficient; α<1, adjust the coefficient α to reduce it from 1 to an appropriate level, and increase the stability margin of the servo system.

9. The method for allocating and suppressing vibration errors of an airborne suspended beam pointing mechanism according to claim 8, characterized in that: The vibration absorber is composed of a spring-damper-mass block. The resonance point frequency and the magnification can be adjusted by adjusting the spring and the mass block until the optical axis jitter of the light beam pointing mechanism at the resonance point is attenuated to less than an error threshold.

10. A vibration error distribution and suppression system for an airborne suspended beam pointing mechanism, used to implement the vibration error distribution and suppression method for an airborne suspended beam pointing mechanism according to any one of claims 1 to 9, characterized in that: It includes a beam pointing mechanism, an excitation module, a stability margin adjustment module, and a vibration absorber; Apply broadband vibration or fixed-frequency vibration to the beam pointing mechanism through the excitation module, record the frequency point where resonance occurs and the magnification of the corresponding resonance point, and obtain the optical axis jitter generated by each frequency point where resonance occurs; The control parameters are adjusted through the stability margin adjustment module to compensate for the insufficient stability margin; The resonance peak is weakened by the vibration absorber to compensate for the larger resonance peak.

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