Liquid rocket unloading control method based on wind attack angle estimation
By estimating the angle of attack using data from the inertial navigation system and the onboard computer, and combining this with the rocket body parameters to calculate the normal force, the problem of measuring the angle of attack of liquid rockets was solved. This enabled precise load reduction control and attitude angle control, simplified hardware requirements, and protected the rocket body structure.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIJING WANHU ZHIHANG TECH CO LTD
- Filing Date
- 2024-01-18
- Publication Date
- 2026-07-07
AI Technical Summary
When liquid-fueled launch vehicles pass through the atmosphere, the additional angle of attack caused by wind is difficult to measure, resulting in large errors in traditional control methods, damage to the rocket body structure, and traditional load reduction methods are complex and require additional hardware equipment.
The angle of attack is estimated by using inertial measurement information and onboard computer data. The normal force is calculated using rocket body parameters, decomposed into engine and aerodynamic forces, and an approximate formula for the actual angle of attack of the rocket body is established. Load reduction control is then performed by combining traditional control gain coefficients.
It achieves accurate tracking and precise control of wind angle of attack, reduces hardware requirements, improves attitude angle control accuracy, adapts to complex flight in high wind areas, reduces rocket body load, and protects the structure.
Smart Images
Figure CN117606306B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of aircraft control technology, and in particular to a liquid rocket load reduction control method based on wind angle of attack estimation. Background Technology
[0002] When a liquid-fueled launch vehicle traverses the atmosphere, it is affected by drastically changing wind shear, resulting in a large angle of attack. While traditional control algorithms can control the attitude angle, the angle of attack remains high, hindering attitude control. Furthermore, the large angle of attack generates significant flight loads, potentially damaging the rocket's structure. Therefore, a wind angle of attack load reduction control method must be incorporated. However, the angle of attack calculated by the onboard computer from the rocket's velocity during flight does not include information on the additional angle of attack caused by wind, which is an unknown quantity.
[0003] Currently, the only device that can directly measure wind angle of attack is the angle-of-attack meter, but its measurements are relatively inaccurate and difficult to track drastic changes in wind angle of attack. Directly incorporating the angle-of-attack meter's measurements into rocket control would introduce significant errors. Other indirect methods for measuring wind angle of attack are also currently scarce, so the actual angle of attack of the rocket body is generally unknown, which poses a challenge to the precise control of liquid-fueled launch vehicles.
[0004] Besides angle-of-attack gauges, another traditional method for load reduction control is to design load reduction by measuring information using a separate gauge. While feasible, this method is not as simple and direct as using the angle of attack directly for load reduction, and it requires a separate gauge, making it more complex to implement. Summary of the Invention
[0005] The purpose of this invention is to provide a liquid rocket load reduction control method based on wind angle of attack estimation, in order to solve the problems mentioned in the background art. To achieve the above objective, this invention provides a liquid rocket load reduction control method based on wind angle of attack estimation, comprising: calculating the normal force acting on the y-axis of the rocket body based on rocket body parameters and inertial navigation system measurement information. F y The normal force acting on the y-axis of the arrow body F y Decomposed into the normal force generated by the engine sway angle F y ( d and aerodynamic normal force F y ( α ); determine the aerodynamic normal force F y ( α and the actual angle of attack of the arrow body α An approximate formula for the relationship; calculation of the actual angle of attack of the arrow body. α According to the actual angle of attack of the arrow body α To control the rocket's load reduction.
[0006] Preferably, the step of basing the arrow body on its actual angle of attack... α The control equations for rocket load reduction are as follows:
[0007] d = k 0· d 0+ k α · α ;in, d To meet the servo swing angle requirements, d 0 represents the servo swing angle requirement calculated by the traditional proportional-derivative control algorithm. k 0 represents the traditional control gain coefficient. k α To design the angle of attack control coefficient.
[0008] Preferably, the calculation of the normal force on the rocket body's y-axis based on the rocket body parameters and inertial navigation system measurement information is... F y The calculation formula is as follows: ;in, m For rocket mass, The apparent velocity increment of the rocket body along the y-axis, as measured by the inertial navigation system. T To control the cycle.
[0009] Preferably, the normal force generated by the engine sway angle F y ( d Let ) be approximately equal to 0, and let the normal force on the y-axis of the arrow body be... F y Approximately equal to the aerodynamic normal force F y ( α ).
[0010] Preferably, the step of determining the aerodynamic normal force F y ( α and the actual angle of attack of the arrow body α An approximate formula for the relationship is as follows: ;in, The normal force acting on the y-axis of the arrow body F y The actual angle of attack of the rocket body α The derivative, q The dynamic pressure is calculated in real time by the computer on the arrow. S This is the aerodynamic reference area of the rocket.
[0011] Preferably, the The following formula is used for estimation: ;in, For the Rockets α =2 0 , β =0 0 The normal force coefficients at different Mach numbers are obtained from aerodynamic data tables through Mach number interpolation. Yes This refers to the Mach number calculated in real time by the computer on the rocket.
[0012] Preferably, the calculation of the actual angle of attack of the arrow body α The formula is as follows: .
[0013] The present invention has the following technical effects: (1) The present invention uses the inertial measurement information of the liquid launch vehicle, the calculation information of the onboard computer and other rocket body information to estimate the wind angle of attack, which is much more accurate than the angle of attack table directly measuring the angle of attack, and can track the wind angle of attack information that changes drastically in the wind area in real time. (2) After estimating the wind angle of attack, the present invention controls the angle of attack, which is more accurate than the traditional control method that only controls the attitude angle, and can adapt to the more complex flight conditions in the wind area. (3) The present invention can achieve precise control of attitude angle, angular velocity and angle of attack at the same time through the coordinated control of the traditional control gain coefficient and the design angle of attack control coefficient, which is more accurate and advanced than the traditional control method. (4) The present invention performs direct load reduction control after estimating the wind angle of attack through inertial measurement information, which reduces the need for angle of attack tables, load tables and other devices compared with the traditional load reduction method, making it simpler and more effective. Attached Figure Description
[0014] Figure 1 This is a flowchart of a liquid rocket load reduction control method based on wind angle of attack estimation, according to an embodiment of the present invention. Implementation
[0015] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.
[0016] The rocket body coordinate system of this invention is as follows: the origin O is the rocket's center of mass; the Ox axis points towards the nose along the theoretical rocket body axis; the Oy axis lies in the rocket's longitudinal symmetry plane, perpendicular to the Ox axis and pointing towards the reference direction; the Oz axis, together with the Ox and Oy axes, forms a right-handed rectangular coordinate system. The rocket body y-axis described in this invention is the Oy axis in the rocket body coordinate system.
[0017] like Figure 1 As shown, the liquid rocket load reduction control method based on wind angle of attack estimation according to an embodiment of the present invention includes:
[0018] Step S1: Calculate the normal force on the rocket body along the y-axis based on the rocket body parameters and inertial navigation system measurement information. Fy The calculation formula is as follows: ;in, m For rocket mass, The apparent velocity increment of the rocket body along the y-axis, as measured by the inertial navigation system. T To control the cycle.
[0019] Step S2: The normal force on the y-axis of the arrow body F y Decomposed into the normal force generated by the engine sway angle F y ( d and aerodynamic normal force F y ( α Expressed in formulas, that is... F y = F y ( d )+ F y ( α Since the engine lever arm is longer than the aerodynamic lever arm, when the torque is balanced, the normal force on the y-axis of the rocket body can be approximated. F y It is mainly generated by aerodynamic forces, while the normal force generated by the engine sway angle is... F y ( d The value is approximately 0. Based on the estimation, the normal force generated by the engine sway angle is approximated as 0. F y ( d Let's assume it's approximately equal to 0, then express it using a formula. F y ( d Since y = 0, the normal force on the arrow body along the y-axis is approximately 0. F y Approximately equal to the aerodynamic normal force F y ( α ), expressed in formula F y ≈ F y ( α ).
[0020] Determine the aerodynamic normal force F y ( α and the actual angle of attack of the arrow body α An approximate formula for the relationship. The aerodynamic normal force generated under small angle of attack conditions can be expressed as: ;in, The normal force acting on the y-axis of the arrow body F yThe actual angle of attack of the rocket body α The derivative, q The dynamic pressure is calculated in real time by the computer on the arrow. S This represents the aerodynamic reference area of the rocket. An approximate method was used for estimation. During rocket flight, the trajectory was stable, operating at a low angle of attack and with minimal sideslip. Angle of attack can be used α =2 0 Sideslip angle β =0 0 The aerodynamic data are calculated by Mach number interpolation, and can be expressed by the formula: ;in, For the Rockets α =2 0 , β =0 0 The normal force coefficients at different Mach numbers are obtained from aerodynamic data tables through Mach number interpolation. Yes This refers to the Mach number calculated in real time by the computer on the rocket.
[0021] Step S4: Calculate the actual angle of attack of the arrow. α .because F y ≈ F y ( α ),Right now ,Will Substituting into the formula, the actual angle of attack of the arrow body, which includes wind angle of attack information, can be obtained. α , .
[0022] Step S5: Based on the actual angle of attack of the arrow body α The rocket is subjected to load reduction control. In this embodiment, load reduction control is performed on the actual angle of attack in the high wind region, which includes wind angle of attack information. The control equation is as follows: d = k 0· d 0+ k α · α ;in, d To meet the servo swing angle requirements, d 0 represents the servo swing angle requirement calculated by the traditional proportional-derivative control algorithm. k 0 represents the traditional control gain coefficient. k α To design the angle of attack control coefficient.
[0023] This embodiment has the following technical effects: (1) This embodiment uses the inertial measurement information of the liquid launch vehicle, the calculation information of the onboard computer and other rocket body information to estimate the wind angle of attack, which is much more accurate than directly measuring the angle of attack using an angle of attack table, and can track the wind angle of attack information that changes drastically in the wind zone in real time. (2) After estimating the wind angle of attack, this embodiment controls the angle of attack, which is more accurate than the traditional control method that only controls the attitude angle, and can adapt to the more complex flight conditions in the wind zone. Controlling the angle of attack in the wind zone within a small range creates good conditions for the rocket's stable flight and load reduction control in the wind zone. (3) This embodiment can achieve precise control of attitude angle, angular velocity and angle of attack simultaneously through the coordinated control of the traditional control gain coefficient and the design angle of attack control coefficient, which is more accurate and advanced than the traditional control method. (4) In this embodiment, the wind angle of attack is estimated by inertial measurement information and then the load is reduced directly. Compared with the traditional load reduction method, the angle of attack table, the addition table and other devices are reduced. No new hardware equipment is required. The load reduction control is simpler and more effective. Load reduction control in the windy area is realized, which reduces the load on the rocket in the windy area and avoids adverse effects on the rocket body structure.
[0024] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. "Above" and "below" both include the stated number. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.
[0025] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles of the present invention, and all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of the present invention.
Claims
1. A liquid rocket load reduction control method based on wind angle of attack estimation, characterized in that, including: Calculate the normal force on the rocket body along the y-axis based on the rocket body parameters and inertial navigation system measurement information. F y The calculation formula is as follows: ;in, m For rocket mass, The apparent velocity increment of the rocket body along the y-axis, as measured by the inertial navigation system. T To control the cycle; The normal force on the y-axis of the arrow body F y Decomposed into the normal force generated by the engine sway angle F y ( d and aerodynamic normal force F y ( α ); Determine the aerodynamic normal force F y ( α and the actual angle of attack of the arrow body α An approximate formula for the relationship is as follows: ;in, The y-axis normal force coefficient of the arrow body relative to the actual angle of attack of the arrow body. α The derivative of q The dynamic pressure is calculated in real time by the computer on the arrow. S This is the aerodynamic reference area of the rocket. Calculate the actual angle of attack of the rocket body α ; Based on the actual angle of attack of the arrow α The rocket's load reduction control is implemented using the following control equations: ;in, d To meet the servo swing angle requirements, d 0 represents the servo swing angle requirement calculated by the traditional proportional-derivative control algorithm. k 0 represents the traditional control gain coefficient. k α To design the angle of attack control coefficient.
2. The liquid rocket load reduction control method based on wind angle of attack estimation according to claim 1, characterized in that, The normal force generated by the engine sway angle F y ( d Let ) be approximately equal to 0, and let the normal force on the y-axis of the arrow body be... F y Approximately equal to the aerodynamic normal force F y ( α ).
3. The liquid rocket load reduction control method based on wind angle of attack estimation according to claim 1, characterized in that, The The following formula is used for estimation: ;in, For the rocket at the angle of attack α =2°, sideslip angle β The y-axis normal force coefficients of the rocket body at 0° and different Mach numbers were obtained by interpolation from the aerodynamic data table based on the Mach number. Yes This refers to the Mach number calculated in real time by the computer on the rocket.
4. The liquid rocket load reduction control method based on wind angle of attack estimation according to claim 3, characterized in that, The calculation of the actual angle of attack of the arrow body α The formula is as follows: .