A method for improving the anti-aerodynamic interference capability of a carrier rocket

Abstract

A method for improving the anti-aerodynamic interference capability of a launch vehicle, (1) generating a reduced load trajectory program angle and simultaneously correcting a roll program angle before launching, so that the maximum control force direction of the vehicle body is aligned with the measured wind direction before launching during flight; (2) within the allowable roll correction interval, the normal and lateral visual accelerations are observed by using an observer to deduct the lever arm effect; (3) the aerodynamic interference forces in the lateral and normal directions are obtained by using the visual accelerations after deducting the lever arm effect, and the aerodynamic interference forces are divided by the aerodynamic force coefficients to obtain the flow attack angle and the sideslip angle; (4) the total flow attack angle is calculated, and it is judged whether the total flow attack angle exceeds a threshold value. When the total flow attack angle exceeds the threshold value, the remaining process is continued; when the total flow attack angle is less than the threshold value, the process returns to step (2); (5) the wind direction angle of the incoming flow under the vehicle system is calculated based on the flow attack angle and the sideslip angle; (6) the correction increment of the roll program angle is calculated based on the wind direction angle of the incoming flow, and then a new roll program angle is regenerated.

Description

Technical Field

[0001] This invention relates to a method for improving the aerodynamic interference resistance of launch vehicles, and relates to the field of launch vehicle control system technology. Background Technology

[0002] To reduce launch vehicle testing and launch costs and improve efficiency, some launch vehicles have gradually abandoned the traditional "three-vertical" launch method in favor of a "three-horizontal" launch method, directly erecting and launching after testing. However, due to space constraints, launch vehicles cannot add tail fins to improve static stability, leading to severe aerodynamic interference when flying through windy areas. This interference is even more pronounced with a large fairing, sometimes resulting in insufficient control force and limited control swing angles in windy conditions, severely impacting control system stability and reducing launch probability. For launch vehicles with a traditional "X"-shaped first-stage engine and a circumferential tangential swing, there is an uneven circumferential distribution of control capability, with the maximum control capability being 1.4 times the minimum. If the direction of aerodynamic interference can be identified and the direction of maximum control capability aligned with the interference in real time, the rocket's resistance to aerodynamic interference will be significantly improved. This will fully leverage the control capabilities of this type of rocket configuration to resist aerodynamic interference and enhance flight reliability. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and improve the anti-aerodynamic interference capability of launch vehicles.

[0004] The objective of this invention is achieved through the following technical solutions:

[0005] A method for improving the aerodynamic interference resistance of a launch vehicle includes:

[0006] (1) Before firing, generate the unloaded ballistic program angle and correct the roll program angle so that the direction of the maximum control force of the rocket body is aligned with the wind direction measured before firing during the flight.

[0007] (2) Within the allowable rolling correction range, based on the normal and lateral unloading gauge measurement signals and the rate gyroscope measurement signals, the observer is used to observe the normal and lateral apparent acceleration after deducting the lever arm effect.

[0008] (3) Subtract the aerodynamic damping force and engine yaw control force from the apparent acceleration after deducting the lever effect to obtain the lateral and normal aerodynamic disturbance forces. Divide the aerodynamic disturbance forces by the aerodynamic coefficient to obtain the airflow angle of attack and sideslip angle.

[0009] (4) Calculate the total angle of attack of the airflow and determine whether the total angle of attack exceeds the threshold. If the total angle of attack exceeds the threshold, continue the remaining process; if the total angle of attack is less than or equal to the threshold, return to step (2).

[0010] (5) Calculate the incoming wind direction angle of the rocket body system based on the airflow angle of attack and sideslip angle;

[0011] (6) Calculate and correct the rolling program angle increment based on the incoming wind direction angle, and regenerate the new rolling program angle.

[0012] In the above-mentioned method for improving the aerodynamic interference resistance of launch vehicles, the corrected roll program angle in step (1) is calculated according to the following formula:

[0013] Δγ c0 =min{|φ c i -A w +A0|},i=1,2,…

[0014] Among them, A w The measured wind direction angle before launch is A0, and the launch azimuth angle is φ. c i Δγ is the direction angle of the maximum control force of the arrow body. c0 , where i is the pre-launch roll program angle correction amount, and i is the maximum control force direction number.

[0015] In the above-mentioned method for improving the aerodynamic interference resistance of launch vehicles, the allowable rolling correction interval in step (2) is usually set in the high wind area. The calculation formulas for the normal and lateral apparent acceleration observations after deducting the lever arm effect in step (2) are as follows:

[0016]

[0017]

[0018]

[0019] in, These are the observed normal and lateral apparent accelerations after deducting the lever arm effect, respectively; k is the filter gain; a and b are the filter pole placement parameters; and Xz is the distance from the rocket's center of mass to its theoretical tip. JB ω represents the distance from the mounting position of the gauge to the tip of the arrow. y1 ω z1 These are the yaw and pitch channel rate gyroscope measurements, respectively. These are the measured values ​​for normal and lateral unloading, respectively. These are the apparent acceleration observations in the normal and lateral directions, respectively, after deducting the lever arm effect from the previous frame. The intermediate computation is represented by s, which is a complex frequency domain variable. The observer avoids rate differentiation and uses a low-pass filter network in the forward path to eliminate high-frequency noise from the load shedding and rate gyroscope.

[0020] In the above-mentioned method for improving the aerodynamic interference resistance of launch vehicles, the calculation formulas for the airflow angle of attack and sideslip angle in step (3) are as follows:

[0021]

[0022]

[0023] Where, α q For the angle of attack of the airflow, β q E is the airflow sideslip angle, E5 is the aerodynamic damping force coefficient, E3 is the control force coefficient, and E... 10 For aerodynamic coefficients, δ ψ These are the equivalent pitch and yaw angles of the engine, respectively.

[0024] In the above-mentioned method for improving the aerodynamic interference resistance of launch vehicles, the formula for calculating the total angle of attack of the airflow in step (4) is as follows:

[0025] α m =acos(cos(α) q cos(β) q ))

[0026] In the above-mentioned method for improving the aerodynamic interference resistance of launch vehicles, the incoming wind direction angle φ in step (5) is... q The calculation formula is as follows:

[0027] φ q =atan2(-cos(β) q sin(α) q ),sin(β q ))

[0028] Among them, atan2 is a general inverse trigonometric function that can limit the future wind direction angle range to (-π, π], which facilitates subsequent calculations.

[0029] In the above-mentioned method for improving the aerodynamic interference resistance of launch vehicles, the formula for calculating the roll program angle increment in step (6) is as follows:

[0030]

[0031] Where, Δγ c To correct for the roll program angle increment. The above calculation method helps to minimize the roll program angle correction amount.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] (1) This invention solves the problems of online identification of airflow angle of attack and sideslip angle considering lever effect and calculation of aerodynamic interference direction;

[0034] (2) This invention solves the problem of insufficient utilization of control capabilities and proposes a method that combines pre-launch measured wind correction and real-time flight identification correction, resulting in better correction effect;

[0035] (3) The algorithm of this invention is simple, fully considers the noise filtering of the load reduction and addition table and the rate gyroscope signal, has strong engineering practicality, and does not affect the stability of the system.

[0036] (4) The method of the present invention avoids differentiating the rate signal when observing the apparent acceleration after deducting the lever effect in the normal and lateral directions, thus avoiding differential explosion and meeting the actual needs of engineering use.

[0037] (5) The present invention minimizes the rolling program angle correction amount, and can minimize the rolling program angle correction amount as much as possible during the correction process. Attached Figure Description

[0038] Figure 1 This is a flowchart of the method for improving resistance to aerodynamic interference according to the present invention;

[0039] Figure 2 This is a schematic diagram illustrating the control capability of the tangential pendulum of an "X"-shaped launch vehicle.

[0040] Figure 3 This is a schematic diagram of the pre-launch calculation and correction of the roll program angle;

[0041] Figure 4 This is a block diagram of the airflow angle of attack and sideslip angle observer;

[0042] Figure 5 This is a schematic diagram for calculating the incoming wind direction angle;

[0043] Figure 6 The four-way rudder angle curve does not employ the method of this invention;

[0044] Figure 7 It is a four-way rudder angle curve obtained by using the method of the present invention. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0046] A method for improving the aerodynamic interference resistance of a launch vehicle includes:

[0047] Step (1): Before launch, generate the unloaded ballistic program angle and correct the roll program angle so that the direction of the maximum control force of the rocket body is aligned with the wind direction measured before launch.

[0048] In this embodiment, the corrected roll program angle is calculated according to the following formula:

[0049] Δγ c0 =min{|φ c i -A w +A0|},i=1,2,…

[0050] Among them, A w The measured wind direction angle before launch is A0, and the launch azimuth angle is φ. c i Δγ is the direction angle of the maximum control force of the arrow body. c0 Here, represents the pre-launch roll program angle correction, and 'i' is the maximum control force direction index. For rockets with an "X"-shaped circumferential tangential configuration, there are four maximum control force direction angles: -π / 2, 0, π / 2, and π, as shown below. Figure 2 As shown, when the direction of maximum control capability is aligned with the direction of aerodynamic interference in real time, the ability to resist aerodynamic interference is significantly improved. A schematic diagram of the pre-launch correction roll program angle calculation is shown below. Figure 3 As shown.

[0051] Step (2): Within the allowable rolling correction range, based on the normal and lateral unloading gauge measurement signals and the rate gyroscope measurement signals, an observer is used to observe the normal and lateral apparent acceleration after deducting the lever arm effect.

[0052] In this embodiment, the allowable roll correction interval is typically set in the high wind zone. The normal and lateral apparent accelerations, after deducting the lever arm effect, are obtained through an observer, and the calculation formula for the observed values ​​is as follows:

[0053]

[0054]

[0055]

[0056] in, These are the apparent acceleration observations in the normal and lateral directions after deducting the lever arm effect, respectively; k is the filter gain; a and b are the filter pole placement parameters; and Xz is the distance from the rocket's center of mass to its theoretical tip. JB ω represents the distance from the mounting position of the gauge to the tip of the arrow. y1 ω z1 These are the yaw and pitch channel rate gyroscope measurements, respectively. These are the measured values ​​for normal and lateral unloading, respectively. These are the apparent acceleration observations in the normal and lateral directions, respectively, after deducting the lever arm effect from the previous frame. is an intermediate computational quantity, and s is a complex frequency domain variable.

[0057] The observer design in this invention is as follows: Figure 4 As shown, this observer considers the influence of the lever arm effect, making the observed values ​​of airflow angle of attack and sideslip angle more accurate. During flight, the noise from the load shearing and rate gyroscope signals is severe, and direct differentiation of the rate signal can lead to differential explosion. This observer cleverly avoids the need for differentiation of the rate signal, and a low-pass filter is set in the forward path of the observer. Good observation performance can be obtained by designing the three parameters k, a, and b. It should be noted that, according to the Routh stability criterion, the designed parameters need to meet the following conditions:

[0058]

[0059] Step (3): Subtract the aerodynamic damping force and engine yaw control force from the apparent acceleration after deducting the lever effect to obtain the lateral and normal aerodynamic interference forces. Divide the aerodynamic interference forces by the aerodynamic coefficient to obtain the airflow angle of attack and sideslip angle.

[0060] In this embodiment, the formulas for calculating the airflow angle of attack and sideslip angle are as follows:

[0061]

[0062]

[0063] Where, α q For the angle of attack of the airflow, β q E is the airflow sideslip angle, E5 is the aerodynamic damping force coefficient, E3 is the control force coefficient, and E... 10 For aerodynamic coefficients, δ ψ These are the equivalent pitch and yaw angles of the engine, respectively.

[0064] For a launch vehicle with an "X" shaped circumferential tangential swing, the equivalent engine swing angle is obtained by acquiring four-channel servo feedback, and the calculation method is as follows:

[0065]

[0066]

[0067] Among them, δ1, δ2, δ3 and δ4 are the four-way servo feedback swing angles.

[0068] Step (4): Calculate the total angle of attack of the airflow and determine whether the total angle of attack exceeds the threshold. If the total angle of attack exceeds the threshold, continue the remaining process; if the total angle of attack is less than or equal to the threshold, return to step (2).

[0069] In this embodiment, as Figure 5 As shown, the total airflow angle of attack is the angle between the airflow velocity and the rocket body axis, and the calculation formula is as follows:

[0070] αm =acos(cos(α) q cos(β) q ))

[0071] Step (5): Calculate the incoming wind direction angle of the rocket body system based on the airflow angle of attack and sideslip angle;

[0072] In this embodiment, as Figure 5 As shown, the incoming wind direction angle φ q Defined as the angle between the projection of the airflow velocity onto the OY1Z1 plane of the system and the Z1 axis, it can be calculated based on the airflow angle of attack and sideslip angle, as shown in the following formula:

[0073] φ q =atan2(-cos(β) q sin(α) q ),sin(β q ))

[0074] Among them, atan2 is a general inverse trigonometric function that can limit the future wind direction angle range to (-π, π], which facilitates subsequent calculations.

[0075] Step (6): Calculate the corrected rolling program angle increment based on the incoming wind direction angle, and regenerate the new rolling program angle.

[0076] In this embodiment, the formula for calculating the incremental rolling program angle is as follows:

[0077]

[0078] Where, Δγ c To correct for the roll program angle increment. The above calculation method helps to minimize the roll program angle correction amount.

[0079] Simulations were performed on a launch vehicle with an "X"-shaped circumferential tangential pendulum configuration. Without taking the aforementioned steps, the simulated pendulum angles of the four engines were as follows: Figure 6 As shown, the two engine swing angles are at full swing of 4° in the high wind area, with short-term amplitude limitation, while the other two engines show almost no swing; when the above steps of the present invention are taken, the simulated swing angles of the four engines are as follows: Figure 7 As shown, the swing angles of the four engines are almost identical in the high-wind area, with no full-swing limitation observed. This demonstrates that the present invention can effectively improve the aerodynamic interference resistance of a type of launch vehicle with unevenly distributed circumferential control capabilities, fully exploit the control potential of the launch vehicle, and enhance flight reliability.

[0080] The contents not described in detail in this specification are common knowledge to those skilled in the art.

[0081] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for improving the aerodynamic interference resistance of a launch vehicle, characterized in that, include: (1) Before launch, generate the unloaded ballistic program angle and correct the roll program angle so that the direction of the maximum control force of the rocket body is aligned with the wind direction measured before launch during flight. (2) Within the allowable rolling correction range, based on the normal and lateral load reduction gauge measurement signals and the rate gyroscope measurement signals, the observer is used to observe the normal and lateral apparent acceleration after deducting the lever arm effect; (3) Subtract the aerodynamic damping force and engine sway control force from the apparent acceleration to obtain the lateral and normal aerodynamic interference forces. Divide the aerodynamic interference forces by the aerodynamic coefficient to obtain the airflow angle of attack and sideslip angle. (4) Calculate the total angle of attack of the airflow and determine whether the total angle of attack exceeds the threshold value; When the total angle of attack exceeds the threshold, proceed to step (5); when the total angle of attack is less than or equal to the threshold, return to step (2). (5) Calculate the incoming wind direction angle of the rocket body system based on the airflow angle of attack and sideslip angle; (6) Calculate and correct the roll program angle increment based on the incoming wind direction angle, and regenerate the new roll program angle; The formulas for calculating the normal and lateral apparent acceleration observations after deducting the lever effect in step (2) are as follows: in, , These are the apparent acceleration observations in the normal and lateral directions, after deducting the lever arm effect, respectively. For filter gain, , Configure parameters for filter poles. This is the distance from the arrow's center of mass to its theoretical tip. To indicate the distance between the mounting position of the gauge and the tip of the arrow body. , These are the yaw and pitch channel rate gyroscope measurements, respectively. , These are the measured values ​​for normal and lateral unloading, respectively. , These are the apparent acceleration observations in the normal and lateral directions, respectively, after deducting the lever arm effect from the previous frame. , , , This is for intermediate calculations. For complex frequency domain variables; The formulas for calculating the airflow angle of attack and sideslip angle in step (3) are as follows: in, For the angle of attack of the airflow, The sideslip angle is the airflow angle. This is the aerodynamic damping force coefficient. For control force coefficient, The aerodynamic coefficient, , These are the equivalent pitch and yaw angles of the engine, respectively.

2. The method for improving the aerodynamic interference resistance of a launch vehicle according to claim 1, characterized in that... The formula for calculating the corrected rolling program angle in step (1) is as follows: in, The wind direction angle was measured before launch. For the launch azimuth angle, The angle of maximum control force of the arrow body. This is the pre-launch roll angle correction amount. This is the sequence number of the direction of maximum control force.

3. The method for improving the aerodynamic interference resistance of a launch vehicle according to claim 1, characterized in that... Step (4) The formula for calculating the total angle of attack of the airflow is as follows: 。 4. The method for improving the aerodynamic interference resistance of a launch vehicle according to claim 1, characterized in that... In step (6), the incoming wind direction angle The calculation formula is as follows: 。 5. A method for improving the aerodynamic interference resistance of a launch vehicle according to claim 2, characterized in that... The formula for calculating the rolling program angle increment in step (6) is as follows: in, To correct the rolling program angle increment, The direction of the incoming wind.

6. A method for improving the aerodynamic interference resistance of a launch vehicle according to any one of claims 1 to 5, characterized in that, The first-stage engine of the launch vehicle adopts an X-shaped layout.

7. A method for improving the aerodynamic interference resistance of a launch vehicle according to any one of claims 1 to 5, characterized in that, The control capabilities of a launch vehicle are unevenly distributed circumferentially.

8. A method for improving the aerodynamic interference resistance of a launch vehicle according to any one of claims 1 to 5, characterized in that, The first-stage engine of the launch vehicle is capable of circumferential and tangential swing.

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