CN102139768B

CN102139768B - Attack angle guidance method for reentry flight of sub-orbital vehicle

Info

Publication number: CN102139768B
Application number: CN 201010522829
Authority: CN
Inventors: 张珩; 李文皓; 肖歆昕
Original assignee: Institute of Mechanics of CAS
Current assignee: Guangdong Aerospace Science And Technology Research Institute
Priority date: 2010-10-28
Filing date: 2010-10-28
Publication date: 2013-04-10
Anticipated expiration: 2030-10-28
Also published as: CN102139768A

Abstract

The invention discloses a method for guiding the angle of attack of a suborbital aircraft re-entry flight. The predicted value of the angle of attack design is obtained by simulating and simulating in different time periods. The predicted value of the angle of attack design is always within the fluctuation region of the expected normal overload dynamic balance, so as to realize the dynamic balance of the normal overload in this period of time; using the fitting method, the actual recovery of the aircraft is obtained from the predicted value of the angle of attack design. The design parameters of the angle of attack of the re-entry flight determine the design value of the angle of attack of the re-entry flight of the aircraft; the correction of the drag acceleration integral ratio is introduced at each flight time, so that the drag acceleration integral value of the actual re-entry flight and the predicted drag acceleration integral under the design value of the attack angle The value converges, and then the normal overload of the re-entry flight of the suborbital vehicle is maintained at a predetermined interval in the dynamic balance segment composed of each time period, so as to achieve the purpose of reducing the peak value of the normal overload of the suborbital re-entry flight.

Description

An Angle of Attack Guidance Method for Suborbital Vehicle Reentry Flight

技术领域technical field

本发明涉及制导控制技术领域，特别是涉及一种亚轨道飞行器再入飞行的攻角制导方法。The invention relates to the technical field of guidance and control, in particular to an angle-of-attack guidance method for reentry flight of a suborbital aircraft.

背景技术Background technique

亚轨道飞行器作为航空与航天有机结合的产物，具备既能够提供地区覆盖、又有利于应急投送和快速反应的应用优势，其活动区域——近空间处于既可威胁航天器，又可制约航空活动的敏感区域，已成为航空航天研究领域的新热点和战略高技术的增长点。As the product of the organic combination of aviation and spaceflight, suborbital vehicles have the application advantages of providing regional coverage, emergency delivery and rapid response. Its active area—near space—is not only a threat to spacecraft, but also restricts aviation. It has become a new hotspot in the field of aerospace research and a growth point of strategic high technology.

飞行器再入飞行是指航天器或航空器从地球大气层外或边缘重新进入地球大气层内部直至着陆的飞行过程。Aircraft reentry flight refers to the flight process of a spacecraft or aircraft re-entering the earth's atmosphere from the outside or edge of the earth's atmosphere until it lands.

亚轨道飞行器的再入飞行过程与航天飞机的再入飞行既有相似之处又有不同特性，相似处在于：都进行跨大气层的再入飞行，再入的飞行动力学描述也基本一致；不同之处在于：其再入大气过程的特性不同。The re-entry flight process of the suborbital vehicle and the re-entry flight of the space shuttle have both similarities and different characteristics. The difference is that the characteristics of the re-entry process are different.

亚轨道飞行器的飞行动能(速度3～10Ma)远小于航天飞机再入初期的动能(速度25Ma)，使得亚轨道飞行器不能像航天飞机那样在较高的大气边缘获得足够的升力实现平衡滑翔，导致其再入飞行高度迅速下降。随着高度下降，大气密度急剧上升，造成亚轨道飞行器的过载、热流、动压峰值同时出现(与航天飞机先热流、再过载、最后动压的三段式峰值特性完全不同)。其中，过载特别是法向过载增加的尤为明显。The flight kinetic energy (speed 3-10Ma) of the suborbital vehicle is much smaller than the kinetic energy (speed 25Ma) of the space shuttle at the initial stage of re-entry, so that the suborbital vehicle cannot obtain enough lift to achieve balanced glide at the edge of the atmosphere like the space shuttle, resulting in Its reentry flight altitude dropped rapidly. As the altitude drops, the density of the atmosphere rises sharply, causing the overload, heat flow, and dynamic pressure peaks of the suborbital vehicle to appear at the same time (completely different from the space shuttle's three-stage peak characteristic of first heat flow, then overload, and finally dynamic pressure). Among them, the increase of overload, especially the normal overload is particularly obvious.

虽然亚轨道飞行器的再入速度低，其再入过程热流小于航天飞机再入热流，但过载特别是法向过载却高出航天飞机一倍以上。当法向过载较大时，飞行器的机载人员和设备需要能够承受较大过载，对机载人员和设备的承压能力要求较高；同时，飞行器的机体所受的剪切力较大，容易产生变形，甚至折断，为确保飞行安全，需要对飞行器进行加固或采用新型材料，致使亚轨道飞行器的研究和运行成本大幅度增加。Although the re-entry speed of the suborbital vehicle is low, and the heat flow during re-entry is smaller than that of the space shuttle, the overload, especially the normal overload, is more than twice as high as that of the space shuttle. When the normal overload is large, the airborne personnel and equipment of the aircraft need to be able to withstand a large overload, and the requirements for the pressure bearing capacity of the airborne personnel and equipment are relatively high; at the same time, the shear force suffered by the aircraft body is relatively large. It is easy to deform or even break. In order to ensure flight safety, it is necessary to reinforce the aircraft or use new materials, resulting in a substantial increase in the research and operation costs of suborbital aircraft.

因此，降低法向过载对于亚轨道飞行器尤为重要。而降低法向过载的关键在于飞行器再入攻角的设计与制导。Therefore, reducing normal overload is particularly important for suborbital vehicles. The key to reducing the normal overload lies in the design and guidance of the re-entry angle of attack of the aircraft.

制导是指导引和控制飞行器按照一定规律飞向目标或预定轨道的技术和方法。对于飞行器再入过程中的攻角制导而言，就是使再入攻角按照一定规律进行调整，达到飞行器的飞行要求。具体的，通过对攻角进行设计得到设计攻角目标值，然后按照一定规律对该设计攻角目标值进行修正，得到攻角制导值。由此可见，设计攻角对攻角制导起到至关重要的作用。Guidance is the technology and method to guide and control the aircraft to fly to the target or predetermined orbit according to certain rules. For the angle-of-attack guidance during the re-entry process of the aircraft, it is to adjust the re-entry angle of attack according to certain rules to meet the flight requirements of the aircraft. Specifically, the target value of the design angle of attack is obtained by designing the angle of attack, and then the target value of the design angle of attack is corrected according to a certain rule to obtain the guidance value of the angle of attack. It can be seen that the design angle of attack plays a crucial role in the angle of attack guidance.

目前，对亚轨道飞行器再入攻角的设计方案多沿用航天飞机再入返回时的设计方法，将攻角设计为速度或时间的一次函数，通过分析在该攻角方案下D-V图(阻力加速度-速度图)中的再入走廊，来确定设计攻角。以攻角-速度为例，二者之间的函数关系可以为：At present, most of the design schemes for the re-entry angle of attack of suborbital vehicles follow the design method of space shuttle re-entry and return, and the angle of attack is designed as a linear function of speed or time. By analyzing the D-V diagram (drag acceleration - the reentry corridor in the velocity diagram) to determine the design angle of attack. Taking angle of attack-velocity as an example, the functional relationship between the two can be:

$α α = = \{{α α}_{00} - - \frac{{α α}_{00} - - {α α}_{end end}}{{V V}_{11} - - {V V}_{22}}, \begin{matrix} {α α}_{00} & V V &GreaterEqual; &Greater Equal; {V V}_{11} \\ (({V V}_{11} - - V V)) & {V V}_{11} &GreaterEqual; &Greater Equal; V V &GreaterEqual; &Greater Equal; {V V}_{22} \\ {α α}_{end end} & V V \leq \leq {V V}_{22} \end{matrix} - - - - - - ((11))$

式(1)中：α为设计攻角；α₀为设计攻角初始值；α_end为设计攻角目标值；V₁为设计攻角开始调整时飞行器速度的初始值；V₂为设计攻角调整至α_end时飞行器速度值；V为飞行器飞行速度值。In formula (1): α is the design angle of attack; α ₀ is the initial value of the design angle of attack; α _end is the target value of the design angle of attack; V ₁ is the initial value of the aircraft speed when the design angle of attack starts to adjust; V ₂ is the design attack angle The speed value of the aircraft when the angle is adjusted to α _end ; V is the flight speed value of the aircraft.

式(1)中，飞行器开始再入时，设计攻角α保持所述设计攻角初始值α0，当飞行器实时速度值V达到设计攻角开始调整时飞行器速度的初始值V₁时，开始以为下降斜率进行调整，直至设计攻角α达到所述设计攻角目标值α_end。In formula (1), when the aircraft starts re-entry, the design angle of attack α keeps the initial value of the design angle of attack α0, and when the real-time velocity value V of the aircraft reaches the initial value _V1 of the aircraft speed when the design angle of attack starts to adjust, it starts to Adjustments are made for the descending slope until the design angle of attack α reaches the design angle of attack target value α _end .

发明人在研究过程中发现，现有的攻角设计方法，攻角调整的下降斜率为一固定值，使得速度相对较低的亚轨道飞行器再入过程中法向过载体现为单峰特点或双峰特点，且法向过载峰值较大。因此，基于现有攻角设计方法的攻角制导方法，也同样具有法向过载峰值过大的问题。In the course of the research, the inventors found that in the existing angle of attack design method, the descending slope of the adjustment of the angle of attack is a fixed value, so that the normal overload during the reentry process of the suborbital vehicle with a relatively low speed is characterized by a single peak or a double peak. peak characteristics, and the peak value of the normal overload is relatively large. Therefore, the angle-of-attack guidance method based on the existing angle-of-attack design method also has the problem that the peak value of the normal overload is too large.

发明内容Contents of the invention

有鉴于此，本发明的目的在于提供一种亚轨道飞行器再入飞行的攻角制导方法，能够降低飞行器再入过程中的法向过载峰值。In view of this, the object of the present invention is to provide an angle of attack guidance method for suborbital vehicle re-entry flight, which can reduce the normal overload peak value during the re-entry process of the vehicle.

本发明实施例提供一种亚轨道飞行器再入飞行的攻角制导方法，包括以下步骤：An embodiment of the present invention provides an angle-of-attack guidance method for reentry flight of a suborbital vehicle, comprising the following steps:

步骤1、在飞行器的再入飞行之前，获取再入攻角的设计值，所述再入攻角的设计值表示为：Step 1. Before the re-entry flight of the aircraft, the design value of the re-entry angle of attack is obtained, and the design value of the re-entry angle of attack is expressed as:

${α α}_{des des} = = \{\begin{matrix} {α α}_{00} & V V &GreaterEqual; &Greater Equal; {V V}_{11} \\ {b b}_{11} + + {b b}_{22} \cdot &Center Dot; v v + + {b b}_{33} \cdot \cdot {e e}^{{b b}_{44} \cdot \cdot h h} & {V V}_{11} &GreaterEqual; &Greater Equal; V V &GreaterEqual; &Greater Equal; {V V}_{22} \\ {α α}_{end end} & V V \leq \leq {V V}_{22} \end{matrix}$

其中，α_des为再入攻角的设计值；α₀为设计攻角初始值；α_end为设计攻角目标值；V₁为设计攻角开始调整时飞行器速度的初始值；V₂为设计攻角调整至α_end时飞行器速度值；b₁、b₂、b₃、b₄为攻角设计系数，V为飞行器飞行速度值，h为飞行器飞行高度值；Among them, α _des is the design value of the re-entry angle of attack; α ₀ is the initial value of the design angle of attack; α _end is the target value of the design angle of attack; V ₁ is the initial value of the aircraft speed when the design angle of attack starts to be adjusted; V ₂ is the design Aircraft speed value when the angle of attack is adjusted to α _end ; b ₁ , b ₂ , b ₃ , b ₄ are the design coefficients of the attack angle, V is the flight speed value of the aircraft, and h is the flight altitude value of the aircraft;

步骤2、利用飞行器再入飞行模型和飞行器同态预测模型，计算得到采用该再入攻角的设计值α_des进行再入飞行时，各飞行时刻对应的阻力加速度预测值

Step 2. Using the aircraft re-entry flight model and the aircraft homomorphic prediction model, calculate the drag acceleration prediction value corresponding to each flight moment when the design value α _des of the re-entry angle of attack is used for re-entry flight

步骤3、在飞行器再入飞行过程中，实时测量得到飞行器当前时刻t的阻力加速度D(t)，结合所述阻力加速度预测值

计算得到当前时刻t对应的设计攻角的修正系数η(t)，具体为：Step 3. During the re-entry flight process of the aircraft, the drag acceleration D(t) of the aircraft at the current moment t is obtained by real-time measurement, combined with the predicted value of the drag acceleration

Calculate the correction coefficient η(t) of the design angle of attack corresponding to the current moment t, specifically:

$η η ((t t)) = = \frac{{&Integral; &Integral;}_{{t t}_{00}}^{t t} \overset{^^}{D D.} ((t t)) dt dt}{{&Integral; &Integral;}_{{t t}_{00}}^{t t} D D. ((t t)) dt dt}$

其中，t₀是指飞行器的再入飞行起始时刻；Among them, t ₀ refers to the starting time of the re-entry flight of the aircraft;

步骤4、实时测量得到飞行器当前的飞行速度v(t)和飞行高度h(t)，利用所述当前设计攻角的修正系数η(t)，对步骤1中得到的再入攻角的设计值进行修正，得到攻角制导值α_cmd：Step 4, real-time measurement obtains the current flight speed v (t) and flight altitude h (t) of the aircraft, utilizes the correction coefficient η (t) of the current design angle of attack, and designs the re-entry angle of attack obtained in step 1 The value is corrected to obtain the angle of attack guidance value α _cmd :

${α α}_{cmd cmd} = = (({b b}_{11} + + {b b}_{22} \cdot \cdot v v ((t t)) + + {b b}_{33} \cdot \cdot {e e}^{{b b}_{44} \cdot \cdot h h ((t t))})) \times \times η η ((t t)) . .$

优选的，在步骤4之后还包括：Preferably, after step 4, it also includes:

步骤5、根据设计攻角初始值α₀对攻角设计系数b1进行修正，使得修正后的攻角设计系数b′1满足：当飞行器再入飞行速度为V₁时，

其中，h₁为飞行器再入飞行速度为V₁时对应的飞行高度，t₁为飞行器再入飞行速度为V₁时对应的飞行时刻；Step 5. Correct the design coefficient b1 of the angle of attack according to the initial value of the design angle of attack α ₀ , so that the modified design coefficient b'1 of the angle of attack satisfies: when the reentry flight speed of the aircraft is V ₁ ,

Wherein, h ₁ is the flight altitude corresponding to when the re-entry flight speed of the aircraft is V ₁ , and t ₁ is the corresponding flight time when the re-entry flight speed of the aircraft is V ₁ ;

具体的，可以采用下式对攻角设计系数b1进行修正：Specifically, the following formula can be used to modify the design coefficient b1 of the angle of attack:

${b b}_{11}^{' '} = = \{\begin{matrix} {b b}_{11}^{start start} & t t = = {t t}_{11} \\ {b b}_{11}^{start start} + + {&Integral; &Integral;}_{11}^{t t} \frac{{b b}_{11} \times \times η η ((t t)) - - {b b}_{11}^{start start}}{ΔT ΔT - - ((t t - - {t t}_{11}))} dt dt & {t t}_{11} < < t t < < {t t}_{11} + + ΔT Δ T \\ {b b}_{11} \times \times η η ((t t)) & t t &GreaterEqual; &Greater Equal; {t t}_{11} + + ΔT ΔT \end{matrix}$

其中， $b_{1}^{start} = α_{0} - (b_{2} \cdot v_{1} + b_{3} \cdot e^{b_{4} \cdot h_{1}}) \times η (t_{1});$ ΔT是预先设定的调整时间间隔；in, $b_{1}^{start} = α_{0} - (b_{2} &Center Dot; v_{1} + b_{3} \cdot e^{b_{4} &Center Dot; h_{1}}) \times η (t_{1});$ ΔT is the preset adjustment time interval;

步骤6、根据所述修正后的攻角设计系数b′₁，得到修正后的攻角制导值α′_cmd：Step 6. According to the modified angle-of-attack design coefficient b′ ₁ , obtain the modified angle-of-attack guidance value α′ _cmd :

${α α}_{cmd cmd}^{' '} = = {b b}_{11}^{' '} + + (({b b}_{22} \cdot &Center Dot; v v ((t t)) + + {b b}_{33} \cdot &Center Dot; {e e}^{{b b}_{44} \cdot &Center Dot; h h ((t t))})) \times \times η η ((t t)) . .$

优选的，所述方法中的步骤1包括：Preferably, step 1 in the method comprises:

步骤11：利用飞行器再入飞行模型和飞行器同态预测模型，获取飞行器法向过载动平衡条件下的各飞行时刻的再入攻角设计预测值 Step 11: Use the aircraft re-entry flight model and aircraft homomorphic prediction model to obtain the design prediction value of the re-entry angle of attack at each flight time under the condition of aircraft normal overload dynamic balance

步骤12：通过飞行器再入飞行模型的模拟仿真，获取飞行器各飞行时刻对应的飞行速度和飞行高度；Step 12: Obtain the flight speed and flight altitude corresponding to each flight moment of the aircraft through the simulation of the re-entry flight model of the aircraft;

步骤13：利用最小二乘法，根据各飞行时刻的再入攻角设计预测值

飞行速度和飞行高度，结合下述表达式，拟合得到攻角设计值的表达式：Step 13: Use the least square method to design the predicted value according to the re-entry angle of attack at each flight time

The flight speed and flight altitude, combined with the following expressions, are fitted to obtain the expression of the design value of the angle of attack:

${α α}_{des des} = = \{\begin{matrix} {α α}_{00} & V V &GreaterEqual; &Greater Equal; {V V}_{11} \\ {b b}_{11} + + {b b}_{22} \cdot &Center Dot; v v + + {b b}_{33} \cdot &Center Dot; {e e}^{{b b}_{44} \cdot \cdot h h} & {V V}_{11} &GreaterEqual; &Greater Equal; V V &GreaterEqual; &Greater Equal; {V V}_{22} \\ {α α}_{end end} & V V \leq \leq {V V}_{22} \end{matrix} . .$

优选的，所述方法中的步骤11包括：Preferably, step 11 in the method comprises:

建立飞行器再入飞行模型以及飞行器再入飞行的同态预测模型，利用再入飞行模型模拟飞行器的再入飞行状态，再入飞行模型以时间为变量进行计算；所述再入飞行模型和预测模型的初始状态为起始时刻t_init对应的飞行器状态；Establish the aircraft re-entry flight model and the homomorphic prediction model of the aircraft re-entry flight, utilize the re-entry flight model to simulate the re-entry flight state of the aircraft, and the re-entry flight model is calculated with time as a variable; the re-entry flight model and prediction model The initial state of is the aircraft state corresponding to the initial moment t _init ;

利用所述飞行器同态预测模型，预测从起始时刻t_init开始、以预置的初始值α_init为设计攻角α进行再入飞行，达到法向过载N_n大于等于预置的法向过载动平衡的期望中值N_{n_want}的时刻t_{1_α}；Using the aircraft homomorphic prediction model, it is predicted that starting from the initial time t _init and taking the preset initial value α _init as the design angle of attack α for re-entry flight, the normal overload N _n is greater than or equal to the preset normal overload Moment t _{1_α} of expected median value N _{n_want} of dynamic balance;

从i＝1，α₀＝α_init起执行以下步骤：Perform the following steps from i=1, α ₀ =α _init :

步骤111：当飞行器再入飞行模型运行至t_{i_α}时刻时，从再入飞行模型中获取飞行器再入飞行至t_{i_α}时刻的攻角值α_i-1，利用飞行器同态预测模型，预测以飞行器t_{i_α}时刻的飞行状态为所述同态预测模型的初始状态、以α_i-1-k′_{_α_i}(t_-t_{i_α})为设计攻角α进行再入飞行时，飞行器的第i首个法向过载峰值

其中，k′_{_α_i}＜k_{_α_i-1}，当i＝1，k′_{_α_1}＝k_init，k_init为攻角下降斜率初始值，k_init≥0；Step 111: When the aircraft re-entry flight model runs to the time t _{i_α} , obtain the angle of attack value α _i-1 of the aircraft re-entry flight to the time t _{i_α} from the re-entry flight model, and use the aircraft homomorphic prediction model to predict the aircraft The flight state at time t _{i_α} is the initial state of the homomorphic prediction model, and when α _i-1 -k′ _{_α_i} (t _- t _{i_α} ) is the design angle of attack α for reentry flight, the ith first method of the aircraft peak overload

Among them, k′ _{_α_i} <k _{_α_i-1} , when i=1, k′ _{_α_1} = _kinit , _kinit is the initial value of the angle of attack descending slope, _kinit ≥ 0;

步骤112：比较所述第i首个法向过载峰值和期望的法向过载动平衡的波动区域[N_{n_want}±ΔN_n]，根据比较结果对设计攻角的下降斜率k′_{_α_i}进行调整，直到所述第i首个法向过载峰值处于所述期望的法向过载动平衡的波动区域[N_{n_want}±ΔN_n]内，并确定此时对应的设计攻角下降斜率k_{_α_i}；所述ΔN_n为预置的法向过载波动限制值；Step 112: Comparing the ith first normal overload peak value and the fluctuation area [N _{n_want} ±ΔN _n ] of the expected normal overload dynamic balance, adjust the descending slope k′ _{_α_i} of the design angle of attack according to the comparison results until the ith first normal overload peak value Be in the fluctuation region [N _{n_want} ±ΔN _n ] of the expected normal overload dynamic balance, and determine the corresponding design angle of attack descending slope k _{_α_i} at this time; the ΔN _n is the preset normal overload fluctuation limit value ;

步骤113：利用飞行器同态预测模型，预测以t_{i_α}时刻飞行器的飞行状态为所述同态预测模型的初始状态、以α_i-1-k_{_α_i}(t-t_{i_α})为设计攻角α进行再入飞行时，飞行器的法向过载N_n经过所述第i首个法向过载峰值后、脱离所述期望的法向过载动平衡的波动区域[N_{n_want}±ΔN_n]的时刻t_{i+1_α}；Step 113: Using the aircraft homomorphic prediction model, predict the flight state of the aircraft at time t _{i_α} as the initial state of the homomorphic prediction model, and use α _i-1 -k _{_α_i} (tt _{i_α} ) as the design angle of attack α for reentry During flight, the normal overload _N of the aircraft passes through the ith first normal overload peak value Afterwards, the moment t _{i+1_α} when departing from the fluctuation region [N _{n_want} ±ΔN _n ] of the expected normal overload dynamic balance;

步骤114：设定[t_{i_α}，t_{i+1_α}]时间段内，设计攻角α为α_i-1-k_{_α_i}(t-t_{i_α})；Step 114: Set the design angle of attack α to be α _i _-1 -k _{_α_i} (tt _{i_α} ) within the time period [t _{i_α} , t i+1_α ];

步骤115：当所述下降斜率k_{_α_i}小于等于预设的k₀时，飞行器的法向过载动平衡结束，结束流程；否则，i加1，返回步骤111。Step 115: When the descending slope _{k_α_i} is less than or equal to the preset _k0 , the normal overload dynamic balance of the aircraft ends, and the process ends; otherwise, i is incremented by 1, and the process returns to step 111.

优选的，所述方法还包括：当i大于等于2时，对t_{i+1_α}的更新，具体为：Preferably, the method further includes: when i is greater than or equal to 2, updating t _{i+1_α} , specifically:

在[t_{i_α}，t_{i+1_α}]时间段内，不断的以飞行器当前在再入飞行模型中的飞行状态作为同态预测模型的初始状态，预测从当前时刻开始、以α_i-1-k_{_α_i}(t-t_{i_α})为设计攻角α进行再入飞行时，飞行器的法向过载N_n经过所述第i首个法向过载峰值

后、脱离所述期望的法向过载动平衡的波动区域[N_{n_want}±ΔN_n]的时刻t′_{i+1_α}，以t′_{i+1_α}作为更新后的t_{i+1_α}。In the time period [t _{i_α} , t _{i+1_α} ], the current flight state of the aircraft in the re-entry flight model is continuously used as the initial state of the homomorphic prediction model, and the prediction starts from the current moment, with α _i-1 -k _{_α_i} (tt _{i_α} ) is the design angle of attack α during re-entry flight, the normal overload N _n of the aircraft passes through the ith first normal overload peak value

Afterwards, at the moment t′ _{i+1_α} when the fluctuation region [N _{n_want} ±ΔN _n ] departs from the expected normal overload dynamic balance, take t′ _{i+1_α} as the updated t _{i+1_α} .

优选的，当且仅当i＝1时，设定调整时间提前量为Δt_α，在[t_init，(t_{1_α}-Δt_α)]时间段内，飞行器再入飞行的设计攻角α等于初始值α_init；Preferably, if and only when i=1, the adjustment timing advance is set to Δt _α , and within the time period [t _init , (t _{1_α} -Δt _α )], the design angle of attack α of the reentry flight of the aircraft is equal to the initial value α _init ;

当飞行器再入飞行模型运行至t_{1_α}-Δt_α时刻时，利用飞行器同态预测模型，预测以飞行器t_{1_α}-Δt_α时刻的飞行状态为所述同态预测模型的初始状态、以α₀-k′_{_α_1}(t-t_{1_α}+Δt_α)为设计攻角α进行再入飞行时，飞行器的第一首个法向过载峰值 When the aircraft re-entry flight model runs to the time t _{1_α} -Δt _α , the homomorphic prediction model of the aircraft is used to predict the flight state of the aircraft at the time t _{1_α} -Δt _α as the initial state of the homomorphic prediction model, and α ₀ - k′ _{_α_1} (tt _{1_α} +Δt _α ) is the first normal overload peak value of the aircraft during reentry flight at the design angle of attack α

比较所述第一首个法向过载峰值和所述期望的法向过载动平衡的波动区域[N_{n_want}±ΔN_n]，根据比较结果对设计攻角的下降斜率k_{_α}进行调整，直到所述第一首个法向过载峰值处于所述期望的法向过载动平衡的波动区域[N_{n_want}±ΔN_n]内，并确定此时对应的设计攻角下降斜率k_{_α_1}；Compare the first normal overload peak value with the first and the fluctuation region [N _{n_want} ±ΔN _n ] of the expected normal overload dynamic balance, adjust the descending slope k _{_α} of the design angle of attack according to the comparison result until the first normal overload peak Be in the fluctuation region [N _{n_want} ±ΔN _n ] of the expected normal overload dynamic balance, and determine the corresponding design angle of attack descending slope k _{_α_1} at this time;

利用飞行器同态预测模型，预测以t_{1_α}-Δt_α时刻飞行器的飞行状态为所述同态预测模型的初始状态、以α_init-k_{_α_1}(t-t_{1_α}+Δt_α)为设计攻角α进行再入飞行时，飞行器的法向过载N_n经过所述第一首个法向过载峰值

后、脱离所述期望的法向过载动平衡的波动区域[N_{n_want}±ΔN_n]的时刻t_{2_α}；Using the homomorphic prediction model of the aircraft, it is predicted that the flight state of the aircraft at time t _{1_α} -Δt _α is the initial state of the homomorphic prediction model, and α _init -k _{_α_1} (tt _{1_α} +Δt _α ) is the design angle of attack α for further When entering the flight, the normal overload _N of the aircraft passes through the first first normal overload peak value

Afterwards, the moment t _{2_α} when departing from the fluctuation region [N _{n_want} ±ΔN _n ] of the expected normal overload dynamic balance;

设定[t_{1_α}-Δt_α，t_{2_α}]时间段内，设计攻角α为α_init-k_{_α_1}(t-t_{1_α}+Δt_α)。Set the time period [t _{1_α} -Δt _α , t _{2_α} ], the design angle of attack α is α _init -k _{_α_1} (tt _{1_α} +Δt _α ).

优选的，所述方法还包括：当i＝1时，对t_{1_α}的更新，具体为：Preferably, the method further includes: when i=1, updating t _{1_α} , specifically:

在t_init≤t≤(t_{1_α}-Δt_α)内，不断的以飞行器当前在再入飞行模型中的飞行状态作为同态预测模型的初始状态，预测从当前时刻开始、以初始值α_init为设计攻角α进行再入飞行，达到法向过载N_n大于等于法向过载动平衡的期望中值N_{n_want}的时刻t′_{1_α}，以t′_{1_α}作为更新后的t_{1_α}。Within t _init ≤t≤(t _{1_α} -Δt _α ), the current flight state of the aircraft in the re-entry flight model is continuously taken as the initial state of the homomorphic prediction model, and the prediction starts from the current moment, with the initial value α _init as Design the angle of attack α for re-entry flight, and reach the moment t′ _{1_α} when the normal overload N _n is greater than or equal to the expected median value N _{n_want} of the normal overload dynamic balance, and take t′ _{1_α} as the updated t _{1_α} .

优选的，所述方法中步骤112中所述根据比较结果对设计攻角的下降斜率k′_{_α_i}进行调整，具体为：Preferably, in the method described in step 112, the descending slope _{k'_α_i} of the design angle of attack is adjusted according to the comparison result, specifically:

若

增大设计攻角的下降斜率k′_{_α_i}；like

Increase the descending slope k′ _{_α_i} of the design angle of attack;

若

减小设计攻角的下降斜率k′_{_α_i}。like

Decrease the descending slope k′ _{_α_i} of the design angle of attack.

优选的，所述增大或减小设计攻角的下降斜率k′_{_α_i}具体为：Preferably, the descending slope _{k'_α_i} of said increase or decrease design angle of attack is specifically:

对所述设计攻角的下降斜率k′_{_α_i}增加或减少一个预设的调整量Δk_{_α}。A preset adjustment amount Δk _{_α} is added or decreased to the descending slope k′ _{_α_i} of the design angle of attack.

根据本发明提供的具体实施例，本发明公开了以下技术效果：According to the specific embodiments provided by the invention, the invention discloses the following technical effects:

本发明实施例所述方法，首先通过仿真模拟，分时间段对获取攻角设计的预测值，对于每一时间段，利用飞行器同态预测模型，找到使得飞行器的法向过载值始终处于期望的法向过载动平衡的波动区域内的攻角设计预测值，实现该时间段内的法向过载动态平衡；随后利用拟合方法，由攻角设计预测值得到飞行器实际再入飞行的攻角设计参数，确定飞行器再入飞行攻角设计值；然后在各飞行时刻引入阻力加速度积分比修正，使得实际再入飞行的阻力加速度积分值与攻角设计值下的预测阻力加速度积分值趋同，进而使得飞行器再入飞行的法向过载实现动态平衡，达到法向过载动态平衡的制导目的。The method described in the embodiment of the present invention first obtains the predicted value of the angle of attack design in time segments through simulation, and for each time segment, uses the aircraft homomorphic prediction model to find the normal overload value of the aircraft that is always at the desired value The predicted value of the angle of attack design in the fluctuation region of the normal overload dynamic balance is used to realize the dynamic balance of the normal overload within this time period; then, the actual re-entry flight design of the aircraft is obtained from the predicted value of the angle of attack design by using the fitting method Parameters to determine the design value of the re-entry flight angle of attack of the aircraft; then introduce the correction of the drag acceleration integral ratio at each flight time, so that the drag acceleration integral value of the actual re-entry flight and the predicted drag acceleration integral value under the design value of the attack angle converge, and then make The normal overload of the re-entry flight of the aircraft is dynamically balanced, and the guidance purpose of the dynamic balance of the normal overload is achieved.

与现有技术中采用唯一固定的攻角调整下降斜率相比，能够使得各时间段内的法向过载在期望的波动区域内小幅度波动，使得法向过载由单/双峰变为平峰，实现了各时间段内的法向过载动平衡，达到降低飞行器再入过程中的法向过载峰值的目的。Compared with the use of the only fixed angle of attack to adjust the descending slope in the prior art, it can make the normal overload in each time period fluctuate in a small range within the expected fluctuation area, so that the normal overload changes from single/double peaks to flat peaks, The dynamic balance of the normal overload in each time period is realized, and the purpose of reducing the peak value of the normal overload during the reentry process of the aircraft is achieved.

附图说明Description of drawings

图1为本发明实施例一的亚轨道飞行器再入飞行的攻角制导方法流程图；Fig. 1 is the flow chart of the angle of attack guidance method of suborbital vehicle re-entry flight according to Embodiment 1 of the present invention;

图2为本发明实施例二的亚轨道飞行器再入飞行的攻角制导方法流程图；Fig. 2 is the flow chart of the angle-of-attack guidance method of the reentry flight of the suborbital vehicle according to Embodiment 2 of the present invention;

图3为采用本发明方法进行仿真时飞行器再入飞行的高度和速度演化图；Fig. 3 is the height and velocity evolution figure of aircraft reentry flight when adopting the method of the present invention to simulate;

图4为图3所示过载动平衡时间段内飞行器对应的设计攻角、速度倾侧角和法向过载演化图；Fig. 4 is the corresponding design attack angle, velocity roll angle and normal overload evolution diagram of the aircraft in the overload dynamic balance period shown in Fig. 3;

图5为图3所示过载动平衡时间段内飞行器对应的设计攻角、速度倾侧角与设计攻角的拟合后比对图；Fig. 5 is a comparison chart after fitting of the design angle of attack, the speed roll angle and the design angle of attack corresponding to the aircraft in the overload dynamic balance period shown in Fig. 3;

图6a至图6f为图3所示实际再入飞行法向过载与设计法向过载，在法向过载动平衡条件下的飞行器法向过载的差值图。6a to 6f are difference diagrams of the normal overload of the actual reentry flight shown in FIG. 3 and the design normal overload, and the normal overload of the aircraft under the condition of dynamic balance of the normal overload.

具体实施方式Detailed ways

为使本发明的上述目的、特征和优点能够更加明显易懂，下面结合附图和具体实施方式对本发明作进一步详细的说明。In order to make the above objects, features and advantages of the present invention more comprehensible, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

在亚轨道飞行器再入飞行过程中，其气动力可近似表达为：During the reentry flight of a suborbital vehicle, its aerodynamic force can be approximately expressed as:

$\{\begin{matrix} F f = = \sqrt{{L L}^{22} + + {D D.}^{22}} \\ L L = = \frac{11}{22} {ρv ρv}^{22} S S * * cl cl \\ D D. = = \frac{11}{22} {ρv ρv}^{22} S S * * cd cd \end{matrix} - - - - - - ((22))$

其中，F为飞行器所受的气动力；L为气动升力；D为气动阻力；S为飞行器参考面积；V为飞行器飞行速度；ρ为大气密度；cl、cd为气动参数，分别为升力系数和阻力系数，均与攻角大小正相关。Among them, F is the aerodynamic force on the aircraft; L is the aerodynamic lift; D is the aerodynamic drag; S is the reference area of the aircraft; V is the flight speed of the aircraft; The drag coefficient is positively correlated with the angle of attack.

根据公式(2)可知，由于气动参数cl、cd与攻角正相关，攻角的减小会引起气动力F的减小；飞行器飞行速度V的减小也会引起气动力F减小。而飞行器再入过程中，随着高度的迅速下降，大气密度ρ呈指数型增加，使得气动力F迅速增加。According to formula (2), since the aerodynamic parameters cl and cd are positively correlated with the angle of attack, the decrease of the angle of attack will cause the decrease of the aerodynamic force F; the decrease of the flight speed V of the aircraft will also cause the decrease of the aerodynamic force F. However, during the reentry process of the aircraft, as the altitude drops rapidly, the atmospheric density ρ increases exponentially, which makes the aerodynamic force F increase rapidly.

现有攻角设计方法中，将攻角设计为速度的一次函数。当攻角下降斜率较小时，由于气动参数cl和cd与攻角呈正相关，较大的气动参数使得飞行器再入前期受到较大的气动力F，飞行速度V迅速降低，其法向过载呈现“单峰”特点‘当攻角下降斜率较大时，气动参数cl和cd迅速减小，在一定程度上补偿了增大的大气密度ρ对气动力F的影响，但是，由于再入前期没有得到足够的速度衰减，飞行器进入稠密大气后，其法向过载将再次快速增加，呈现“双峰”特点。In the existing angle of attack design method, the angle of attack is designed as a linear function of velocity. When the descending slope of the angle of attack is small, because the aerodynamic parameters cl and cd are positively correlated with the angle of attack, the larger aerodynamic parameters cause the aircraft to receive a larger aerodynamic force F in the early stage of re-entry, the flight speed V decreases rapidly, and its normal overload presents " "Single peak" characteristic' when the slope of the angle of attack is large, the aerodynamic parameters cl and cd decrease rapidly, which compensates the influence of the increased atmospheric density ρ on the aerodynamic force F to a certain extent. Sufficient speed attenuation, after the aircraft enters the dense atmosphere, its normal overload will increase rapidly again, showing the characteristics of "double peaks".

本发明实施例所述方法，通过调整攻角，使得由攻角减小引起的气动力F减小、飞行速度V衰减引起的气动力F减小、和大气密度ρ增加引起的气动力F增加在飞行器机体法向上达到平衡，使得法向过载在某一设定值附近小幅度波动，使得法向过载由单/双峰变为平峰，实现法向过载动平衡过程。然后通过延长动平衡过程的持续时间，达到降低飞行器再入过程中的法向过载峰值的目的。In the method described in the embodiment of the present invention, by adjusting the angle of attack, the aerodynamic force F caused by the decrease of the angle of attack decreases, the aerodynamic force F caused by the decay of the flight speed V decreases, and the aerodynamic force F caused by the increase of the atmospheric density ρ increases The balance is achieved in the normal direction of the aircraft body, so that the normal overload fluctuates in a small range around a certain set value, so that the normal overload changes from single/double peaks to flat peaks, and the normal overload dynamic balance process is realized. Then, by prolonging the duration of the dynamic balancing process, the purpose of reducing the peak normal overload during the reentry process of the aircraft is achieved.

飞行器的再入飞行过程中，其法向过载一般可以表达为：During the re-entry flight of the aircraft, its normal overload can generally be expressed as:

${N N}_{n no} = = \frac{{F f}_{n no}}{G G} = = \frac{L L cos cos α α + + D D. sin sin α α}{G G} = = \frac{{ρv ρv}^{22} ((cl cl \times \times cos cos α α + + cd cd \times \times sin sin α α))}{22 G G} - - - - - - ((33))$

其中，N_n为飞行器法向过载值；F_n为飞行器所受的气动力F在飞行器机体上的法向分量；L为气动升力；D为气动阻力；V为飞行器飞行速度；ρ为大气密度；α为攻角值；G为飞行器所受重力，等于飞行器质量与当地重力加速度的乘积。Among them, N _n is the normal overload value of the aircraft; F _n is the normal component of the aerodynamic force F on the aircraft body; L is the aerodynamic lift; D is the aerodynamic drag; V is the flight speed of the aircraft; ρ is the atmospheric density ; α is the value of the angle of attack; G is the gravity of the aircraft, which is equal to the product of the mass of the aircraft and the local acceleration of gravity.

由式(3)可见，影响某时刻飞行器法向过载值N_n的主要参数有：攻角值α(与气动参数cl和cd呈正相关)、飞行器飞行速度V和大气密度ρ。It can be seen from formula (3) that the main parameters affecting the normal overload value N _n of the aircraft at a certain moment are: the angle of attack value α (positively correlated with the aerodynamic parameters cl and cd), the flight speed V of the aircraft, and the atmospheric density ρ.

其中，当飞行器的飞行高度在120km内时，对大气密度ρ在高度上求导：Among them, when the flight altitude of the aircraft is within 120km, the altitude derivative of the atmospheric density ρ is obtained:

$\frac{&PartialD; &PartialD; ρ ρ}{&PartialD; &PartialD; h h} = = - - \frac{11}{{H h}_{s the s}} {e e}^{- - \frac{h h}{{H h}_{s the s}}} - - - - - - ((44))$

其中，H_s一恒定值，为7320。Among them, H _s is a constant value, which is 7320.

由式(4)可见，随着高度h下降，大气密度ρ呈指数型增加。It can be seen from formula (4) that as the height h decreases, the atmospheric density ρ increases exponentially.

为实现法向过载值N_n在某一设定值附近小幅度波动，达到降低飞行器再入过程中的法向过载峰值的目的，本发明将攻角制导方法中的攻角设计为：In order to realize that the normal overload value _N fluctuates in a small range near a certain set value and achieve the purpose of reducing the peak value of the normal overload in the reentry process of the aircraft, the present invention designs the angle of attack in the angle of attack guidance method as:

${α α}_{des des} = = \{\begin{matrix} {α α}_{00} & V V &GreaterEqual; &Greater Equal; {V V}_{11} \\ {b b}_{11} + + {b b}_{22} \cdot &Center Dot; v v + + {b b}_{33} \cdot &Center Dot; {e e}^{{b b}_{44} \cdot &Center Dot; h h} & {V V}_{11} &GreaterEqual; &Greater Equal; V V &GreaterEqual; &Greater Equal; {V V}_{22} \\ {α α}_{end end} & V V \leq \leq {V V}_{22} \end{matrix} - - - - - - ((55))$

其中，α_des为设计攻角；α₀为设计攻角初始值；α_end为设计攻角目标值；V₁为设计攻角开始调整时飞行器速度的初始值；V₂为设计攻角调整至α_end时飞行器速度值；b₁、b₂、b₃、b₄为攻角设计系数，V为飞行器飞行速度值，h为飞行器飞行高度值。Among them, α _des is the design angle of attack; α ₀ is the initial value of the design angle of attack; α _end is the target value of the design angle of attack; V ₁ is the initial value of the aircraft speed when the design angle of attack starts to be adjusted; V ₂ is the design angle of attack adjusted to The velocity value of the aircraft at α _end ; b ₁ , b ₂ , b ₃ , and b ₄ are design coefficients for the angle of attack, V is the flight speed value of the aircraft, and h is the flight altitude value of the aircraft.

式(5)中，飞行器开始再入飞行时，设计攻角α_des保持所述设计攻角初始值α₀，当飞行器飞行速度值V达到所述设计攻角开始调整时飞行器速度的初始值V₁时，设计攻角α_des开始以

进行调整，直至设计攻角α_des达到所述设计攻角目标值α_end。In formula (5), when the aircraft starts re-entry flight, the design angle of attack α _des maintains the initial value of the design angle of attack α ₀ , and when the flight speed value V of the aircraft reaches the initial value V of the aircraft speed when the design angle of attack starts to be adjusted ₁ , the design angle of attack α _des begins to

Adjustments are made until the design angle of attack α _des reaches the target value of the design angle of attack α _end .

需要注意的是，设定：当飞行器再入飞行速度为V₁，对应的飞行高度为h₁时，

当飞行器速度再入飞行速度为V₂，对应的飞行高度为h₂时，

α_{end} = b_{1} + b_{2} \cdot v_{2} + b_{3} \cdot e^{b_{4} \cdot h_{2}}

It should be noted that the setting: when the re-entry flight speed of the aircraft is V ₁ and the corresponding flight altitude is h ₁ ,

When the re-entry flight speed of the aircraft is V ₂ and the corresponding flight altitude is h ₂ ,

α_{end} = b_{1} + b_{2} &Center Dot; v_{2} + b_{3} &Center Dot; e^{b_{4} &Center Dot; h_{2}}

参照图1，为本发明实施例一所述的亚轨道飞行器再入飞行的攻角制导方法流程图。所述方法包括以下步骤：Referring to FIG. 1 , it is a flowchart of an angle-of-attack guidance method for suborbital vehicle reentry flight according to Embodiment 1 of the present invention. The method comprises the steps of:

步骤S10：在飞行器的再入飞行之前，获取再入攻角的设计值；所述再入攻角的设计值可以表示为：Step S10: before the re-entry flight of the aircraft, obtain the design value of the re-entry angle of attack; the design value of the re-entry angle of attack can be expressed as:

其中，α_des再入攻角的设计值；α₀为设计攻角初始值；α_end为设计攻角目标值；_V1为设计攻角开始调整时飞行器速度的初始值；V₂为设计攻角调整至α_end时飞行器速度值；b₁、b₂、b₃、b₄为攻角设计系数，V为飞行器飞行速度值，h为飞行器飞行高度值。Among them, α _des is the design value of the re-entry angle of attack; α ₀ is the initial value of the design angle of attack; α _end is the target value of the design angle of attack; _V 1 is the initial value of the aircraft speed when the design angle of attack starts to be adjusted; V ₂ is the design attack angle The velocity value of the aircraft when the angle is adjusted to α _end ; b ₁ , b ₂ , b ₃ , and b ₄ are design coefficients for the angle of attack, V is the flight speed value of the aircraft, and h is the flight altitude value of the aircraft.

具体的，关于获取攻角设计系数b₁、b₂、b₃、b₄的具体过程，在后面内容详细介绍。Specifically, the specific process of obtaining the design coefficients b ₁ , b ₂ , b ₃ , and b ₄ for the angle of attack will be described in detail later.

步骤S20：利用飞行器再入飞行模型和飞行器同态预测模型，计算得到采用该再入攻角的设计值α_des进行再入飞行时，各飞行时刻对应的阻力加速度预测值

Step S20: Using the aircraft re-entry flight model and the aircraft homomorphic prediction model, calculate the drag acceleration prediction value corresponding to each flight time when the design value α _des of the re-entry attack angle is used for re-entry flight

所述飞行器再入飞行模型和同态预测模型主要包括：飞行器再入飞行轨迹动力学及运动学方程；飞行器本体参数，如飞行器质量，参考面积，升、阻力系数与攻角和飞行速度的对应关系表等。The aircraft re-entry flight model and homomorphic prediction model mainly include: aircraft re-entry flight trajectory dynamics and kinematic equations; aircraft body parameters, such as aircraft mass, reference area, lift, drag coefficient, angle of attack and flight speed. relational tables, etc.

考虑到地球为椭球体，采用指数大气率及标准大气下的声速值，在地球旋转坐标系下建立飞行器再入飞行轨迹动力学及运动学方程：Considering that the earth is an ellipsoid, using the exponential atmospheric rate and the sound velocity value under the standard atmosphere, the dynamics and kinematic equations of the reentry flight trajectory of the aircraft are established in the earth rotating coordinate system:

$\frac{dr dr}{dt dt} = = v v sin sin γ γ - - - - - - ((66))$

$\frac{dλ dλ}{dt dt} = = \frac{v v cos cos γ γ cos cos ξ ξ}{r r cos cos ψ ψ} - - - - - - ((77))$

$\frac{dψ dψ}{dt dt} = = \frac{v v cos cos γ γ sin sin ξ ξ}{r r} - - - - - - ((88))$

$\frac{dv dv}{dt dt} = = - - \frac{11}{m m} D D. - - {g g}_{r r} sin sin γ γ + + {ω ω}^{22} r r cos cos ψ ψ ((sin sin γ γ cos cos ψ ψ - - - - - - ((99))$

$- - cos cos γ γ sin sin ξ ξ sin sin ψ ψ))$

$v v \frac{dγ dγ}{dt dt} = = \frac{11}{m m} L L cos cos σ σ - - {g g}_{r r} cos cos γ γ + + \frac{{v v}^{22}}{r r} cos cos γ γ + + 22 ω ω v v cos cos ξ ξ cos cos ψ ψ - - - - - - ((1010))$

$+ + {ω ω}^{22} r r cos cos ψ ψ ((cos cos γ γ cos cos ψ ψ + + sin sin γ γ sin sin ξ ξ sin sin ψ ψ))$

$v v \frac{dξ dξ}{dt dt} = = - - \frac{11}{m m} \cdot \cdot \frac{L L sin sin σ σ}{cos cos γ γ} - - \frac{{v v}^{22}}{r r} cos cos γ γ cos cos ξ ξ tan the tan ψ ψ$

$ωv ω v ((tan the tan γ γ sin sin ξ ξ cos cos ψ ψ - - sin sin ψ ψ)) - - - - - - ((1111))$

$- - \frac{{ω ω}^{22} r r}{cos cos γ γ} cos cos ψ ψ sin sin ψ ψ cos cos ξ ξ - - {g g}_{ψ ψ} \frac{sin sin ξ ξ cos cos ξ ξ}{cos cos γ γ}$

其中：γ、ξ分别为航迹倾角和航迹偏角；ψ、λ分别为地理纬度和地理经度‘σ为飞行器速度倾侧角；L为气动升力；D为气动阻力；m为飞行器质量；v为飞行器飞行速度；r为飞行器与地心的距离；g_r为重力加速度分量；ω为地球自转角速度。Among them: γ and ξ are track inclination and track declination respectively; ψ and λ are geographic latitude and longitude respectively; σ is aircraft velocity roll angle; L is aerodynamic lift; D is aerodynamic drag; m is mass of aircraft; v is the flight speed of the aircraft; r is the distance between the aircraft and the center of the earth; g _r is the gravitational acceleration component; ω is the angular velocity of the earth's rotation.

需要说明的是，利用所述飞行器再入飞行模型和飞行器同态预测模型，计算得到采用一定攻角值进行再入飞行时各飞行时刻对应的阻力加速度值为本领域的公知常识，在此不再详述。It should be noted that, using the aircraft re-entry flight model and the aircraft homomorphic prediction model, the calculated resistance acceleration values corresponding to each flight time when a certain angle of attack value is used for re-entry flight are common knowledge in the field, and are not described herein. More details.

步骤S30：在飞行器再入飞行过程中，实时测量得到飞行器当前时刻t的阻力加速度D(t)，结合所述阻力加速度预测值

计算得到当前时刻t对应的设计攻角的修正系数η(t)。Step S30: During the re-entry flight of the aircraft, the drag acceleration D(t) of the aircraft at the current moment t is obtained by real-time measurement, combined with the predicted value of the drag acceleration

Calculate the correction coefficient η(t) of the design angle of attack corresponding to the current moment t.

其中，当前设计攻角的修正系数η(t)可以通过下式计算得到：Among them, the correction coefficient η(t) of the current design angle of attack can be calculated by the following formula:

$η η ((t t)) = = \frac{{&Integral; &Integral;}_{{t t}_{00}}^{t t} \overset{^^}{D D.} ((t t)) dt dt}{{&Integral; &Integral;}_{{t t}_{00}}^{t t} D D. ((t t)) dt dt} - - - - - - ((1212))$

其中，t₀是指飞行器的再入飞行起始时刻。Among them, t ₀ refers to the starting time of the re-entry flight of the aircraft.

步骤S40：实时测量得到飞行器当前的飞行速度v(t)和飞行高度h(t)，利用所述当前设计攻角的修正系数η(t)，对步骤S10中得到的再入攻角的设计值进行修正，得到攻角制导值α_cmd。Step S40: Real-time measurement obtains the current flight speed v(t) and flight height h(t) of the aircraft, and utilizes the correction coefficient η(t) of the current design angle of attack to design the re-entry angle of attack obtained in step S10 The value is corrected to obtain the angle of attack guidance value α _cmd .

${α α}_{cmd cmd} = = (({b b}_{11} + + {b b}_{22} \cdot &Center Dot; v v ((t t)) + + {b b}_{33} \cdot &Center Dot; {e e}^{{b b}_{44} \cdot &Center Dot; h h ((t t))})) \times \times η η ((t t)) - - - - - - ((1313))$

本发明实施例一所述方法，首先通过仿真模拟，分时间段对获取攻角设计的预测值，对于每一时间段，利用飞行器同态预测模型，找到使得飞行器的法向过载值始终处于期望的法向过载动平衡的波动区域内的攻角设计预测值，实现该时间段内的法向过载动态平衡；随后利用拟合方法，由攻角设计预测值得到飞行器实际再入飞行的攻角设计参数，确定飞行器再入飞行攻角设计值；然后在各飞行时刻引入阻力加速度积分比修正，使得实际再入飞行的阻力加速度积分值与攻角设计值下的预测阻力加速度积分值趋同，进而使得飞行器再入飞行的法向过载实现动态平衡，达到法向过载动态平衡的制导目的。The method described in Embodiment 1 of the present invention first obtains the predicted value of the angle of attack design in time periods through simulation, and for each time period, uses the aircraft homomorphic prediction model to find the normal overload value of the aircraft so that it is always at the desired value. The predicted value of the angle of attack design in the fluctuation region of the normal overload dynamic balance, to achieve the dynamic balance of the normal overload within this time period; then use the fitting method to obtain the actual reentry flight angle of the aircraft from the predicted value of the angle of attack design Design parameters, determine the design value of the aircraft re-entry flight angle of attack; then introduce the correction of the drag acceleration integral ratio at each flight time, so that the drag acceleration integral value of the actual re-entry flight is similar to the predicted drag acceleration integral value under the design value of the attack angle, and then The normal overload of the re-entry flight of the aircraft can be dynamically balanced, and the guidance purpose of the dynamic balance of the normal overload can be achieved.

与现有技术中采用唯一固定的攻角调整下降斜率相比，能够使得各时间段内的法向过载在期望的波动区域内小幅度波动，使得法向过载由单/双峰变为平峰，实现了各时间段内的法向过载动平衡，达到降低飞行器再入过程中的法向过载峰值的目的。Compared with the use of a single fixed angle of attack to adjust the descending slope in the prior art, it can make the normal overload in each time period fluctuate in a small range within the expected fluctuation area, so that the normal overload changes from single/double peaks to flat peaks, The dynamic balance of the normal overload in each time period is realized, and the purpose of reducing the peak value of the normal overload during the reentry process of the aircraft is achieved.

为了满足设计条件，本发明所述方法中还可以对攻角设计系数b1进行修正，使得修正后的攻角设计系数b′₁能够满足再入飞行设计的条件。参照图2，为本发明实施例二所述的亚轨道飞行器再入飞行的攻角制导方法流程图。In order to meet the design conditions, the method of the present invention can also modify the design coefficient b1 of the angle of attack, so that the modified design coefficient _b'1 of the angle of attack can meet the conditions of the reentry flight design. Referring to FIG. 2 , it is a flow chart of the angle-of-attack guidance method for suborbital vehicle reentry flight described in Embodiment 2 of the present invention.

如图2所示，本发明实施例二所述方法中，步骤S10至步骤S40与实施例一所述方法相同，在此不再赘述。实施例二与实施例一所述方法的区别在于，在步骤S40之后，所述方法还包括：As shown in FIG. 2 , in the method described in Embodiment 2 of the present invention, step S10 to step S40 are the same as the method described in Embodiment 1, and will not be repeated here. The difference between the method described in Embodiment 2 and Embodiment 1 is that, after step S40, the method further includes:

步骤S50：根据设计攻角初始值α₀对攻角设计系数b1进行修正，使得修正后的攻角设计系数b′₁满足：当飞行器再入飞行速度为V₁时，

其中，h₁为飞行器再入飞行速度为V₁时对应的飞行高度，t₁为飞行器再入飞行速度为V₁时对应的飞行时刻。Step S50: Correct the design coefficient of the angle of attack b1 according to the initial value of the design angle of attack α ₀ , so that the modified design coefficient of the angle of attack b′ ₁ satisfies: when the reentry flight speed of the aircraft is V ₁ ,

Among them, h ₁ is the flight altitude corresponding to the re-entry flight speed of the aircraft at V ₁ , and t ₁ is the flight time corresponding to the re-entry flight speed of the aircraft at V ₁ .

${b b}_{11}^{' '} = = \{\begin{matrix} {b b}_{11}^{start start} & t t = = {t t}_{11} \\ {b b}_{11}^{start start} + + {&Integral; &Integral;}_{11}^{t t} \frac{{b b}_{11} \times \times η η ((t t)) - - {b b}_{11}^{start start}}{ΔT ΔT - - ((t t - - {t t}_{11}))} dt dt & {t t}_{11} < < t t < < {t t}_{11} + + ΔT Δ T \\ {b b}_{11} \times \times η η ((t t)) & t t &GreaterEqual; &Greater Equal; {t t}_{11} + + ΔT ΔT \end{matrix} - - - - - - ((1414))$

其中，

ΔT是预先设定的调整时间间隔。in,

ΔT is a preset adjustment time interval.

所述调整时间间隔ΔT可以根据实际需要具体设定。例如，可以取5s。The adjustment time interval ΔT can be specifically set according to actual needs. For example, 5s can be taken.

步骤S60：根据所述修正后的攻角设计系数b′₁，得到修正后的攻角制导值α′_cmd。Step S60: Obtain a corrected angle of attack guidance value α' _cmd according to the corrected angle of attack design coefficient b' ₁ .

${α α}_{cmd cmd}^{' '} = = {b b}_{11}^{' '} + + (({b b}_{22} \cdot &Center Dot; v v ((t t)) + + {b b}_{33} \cdot &Center Dot; {e e}^{{b b}_{44} \cdot &Center Dot; h h ((t t))})) \times \times η η ((t t)) - - - - - - ((1515))$

本发明实施例二所述方法，根据设计攻角初始值α₀对攻角设计系数b1进行修正，使得修正后的攻角设计系数b′₁能够满足再入飞行设计的条件。对上述本发明各实施例提供的方法中，所述步骤S10中所述在飞行器的再入飞行之前，获取再入攻角的设计值可以具体包括以下步骤：The method described in Embodiment 2 of the present invention corrects the design coefficient b1 of the angle of attack according to the initial value _α0 of the design angle of attack, so that the modified design coefficient _b'1 of the angle of attack can meet the conditions of the reentry flight design. In the methods provided by the above-mentioned embodiments of the present invention, before the re-entry flight of the aircraft described in step S10, obtaining the design value of the re-entry angle of attack may specifically include the following steps:

步骤S101：利用飞行器同态预测模型，获取飞行器法向过载动平衡条件下的各飞行时刻的再入攻角设计预测值

Step S101: Using the homomorphic prediction model of the aircraft, obtain the design prediction value of the re-entry angle of attack at each flight time under the condition of the aircraft's normal overload dynamic balance

步骤S102：通过飞行器再入飞行模型的模拟仿真，获取飞行器各飞行时刻对应的飞行速度和飞行高度；Step S102: Obtain the flight speed and flight altitude corresponding to each flight moment of the aircraft through the simulation of the re-entry flight model of the aircraft;

步骤S103：利用最小二乘法，根据各飞行时刻的再入攻角设计值

飞行速度和飞行高度，结合式(5)，拟合得到攻角设计系数b₁、b₂、b₃、b₄，将再入攻角设计值表示为：Step S103: Use the least square method to design the value according to the re-entry angle of attack at each flight time

Flight speed and flight altitude, combined with Equation (5), to obtain the design coefficients of the angle of attack b ₁ , b ₂ , b ₃ , b ₄ , and the design value of the re-entry angle of attack is expressed as:

具体的，下面详细介绍步骤S101中利用飞行器再入飞行模型和同态预测模型，获取飞行器法向过载动平衡条件下的各飞行时刻的再入攻角设计预测值

的过程。本发明实施例提供两种获取飞行器再入攻角设计预测值

的具体实施方式。下面分别进行详细介绍。Specifically, the following describes in detail the use of the aircraft re-entry flight model and the homomorphic prediction model in step S101 to obtain the design prediction value of the re-entry angle of attack at each flight time under the condition of the aircraft's normal overload dynamic balance

the process of. The embodiment of the present invention provides two methods for obtaining the design prediction value of the reentry angle of attack of the aircraft

specific implementation. The following are detailed introductions respectively.

第一种实施方式：The first implementation mode:

步骤S201：选取设计攻角α的初始值α_init，以初始值α_init对应的时刻t_init为攻角设计起始时刻。Step S201: Select the initial value α _init of the design angle of attack α, and use the time t _init corresponding to the initial value α _init as the starting time of the angle of attack design.

其中，所述初始值α_init可以根据经验预先设置；也可以由飞行器自分离点自由飞行后获取。Wherein, the initial value α _init can be preset according to experience; it can also be obtained after the aircraft flies freely from the separation point.

一般，α_init的取值可以为35°至45°。当采用较大的设计攻角初始值α_init时，可使飞行器在再入初期得到更多的速度衰减。Generally, the value of α _init may be 35° to 45°. When a larger initial value of the design angle of attack α _init is adopted, the aircraft can obtain more velocity attenuation at the initial stage of reentry.

举例说明由飞行器自分离点自由飞行后获取初始值α_init的过程。假设，飞行器的分离点倾角为20°，在经过无动力上升和再入滑翔至分离点高度时，若飞行器姿态仍为分离点状态，则其攻角将达到40°左右，此时可以选择初始值α_init为40°An example is given to illustrate the process of obtaining the initial value α _init after the aircraft flies freely from the separation point. Assume that the inclination angle of the separation point of the aircraft is 20°. After unpowered ascent and re-entry glide to the height of the separation point, if the attitude of the aircraft is still in the state of the separation point, the angle of attack will reach about 40°. At this time, the initial Value of α _init is 40°

步骤S202：建立飞行器再入飞行模型以及飞行器再入飞行的同态预测模型，利用再入飞行模型模拟飞行器的再入飞行状态，再入飞行模型以时间为变量进行计算。所述再入飞行模型和预测模型的初始状态为攻角设计起始时刻t_init对应的飞行器状态。Step S202: Establishing the re-entry flight model of the aircraft and the homomorphic prediction model of the re-entry flight of the aircraft, using the re-entry flight model to simulate the re-entry flight state of the aircraft, and calculating the re-entry flight model with time as a variable. The initial state of the re-entry flight model and the prediction model is the state of the aircraft corresponding to the initial time t _init of the angle of attack design.

所述飞行器再入飞行模型和同态预测模型建立方法为本领域的公知常识，在此不再详述。The aircraft re-entry flight model and homomorphic prediction model establishment methods are common knowledge in the field, and will not be described in detail here.

步骤S203：设定法向过载动平衡的期望中值N_{n_want}和法向过载波动限制值ΔN_n，则期望的法向过载动平衡的波动区域为[N_{n_want}±ΔN_n]。Step S203: Set the expected median value N _{n_want} of normal overload dynamic balance and the limit value of normal overload dynamic balance ΔN _n , then the expected fluctuation range of normal overload dynamic balance is [N _{n_want} ±ΔN _n ].

具体的，所述法向过载动平衡的期望中值N_{n_want}和法向过载波动限制值ΔN_n可以根据实际需要具体设定。Specifically, the expected median value N _{n_want} of normal overload dynamic balance and the limit value ΔN _n of normal overload dynamic balance can be specifically set according to actual needs.

例如，可以设定法向过载动平衡的期望中值N_{n_want}为飞行器机载人员和设备所能承受的法向过载约束值，法向过载波动限制值ΔN_n为该期望中值N_{n_want}的2％至5％。For example, the expected median value N _{n_want} of the normal overload dynamic balance can be set as the normal overload constraint value that the aircraft onboard personnel and equipment can bear, and the normal overload movement limit value ΔN _n is 2 of the expected median value N _{n_want} % to 5%.

步骤S204：利用飞行器同态预测模型，预测从起始时刻t_init开始、以初始值α_init为设计攻角α进行再入飞行，达到法向过载N_n大于等于法向过载动平衡的期望中值N_{n_want}的时刻t_{1_α}。Step S204: Using the homomorphic prediction model of the aircraft, it is predicted that the re-entry flight will be carried out starting from the initial time t _init with the initial value α _init as the design angle of attack α, and the expected normal overload N _n is greater than or equal to the normal overload dynamic balance. Time t _{1_α} of value N _{n_want} .

步骤S205：设定i＝1；α₀＝α_init。Step S205: Set i=1; α ₀ =α _init .

步骤S206：当飞行器再入飞行运行至t_{i_α}时刻时，从再入飞行模型中获取飞行器再入飞行至t_{i_α}时刻的攻角值α_i-1，利用飞行器同态预测模型，预测以飞行器t_{i_α}时刻的飞行状态为所述同态预测模型的初始状态、以α_i-1-k′_{_α_i}(t-t_{i_α})为设计攻角α进行再入飞行时，飞行器的第i首个法向过载峰值

其中，k′_{_α_i}＜k_{_α_i-1}，当i＝1，k′_{_α_1}＝k_init，k_init为攻角下降斜率初始值，k_init≥0。Step S206: When the aircraft re-entry flight runs to the time t _{i_α} , obtain the value of the angle of attack α _i-1 of the aircraft re-entry flight to the time t _{i_α} from the re-entry flight model, and use the aircraft homomorphic prediction model to predict the aircraft t The flight state at time _{i_α} is the initial state of the homomorphic prediction model, and when α _i-1 -k′ _{_α_i} (tt _{i_α} ) is the design angle of attack α for reentry flight, the ith first normal overload peak value of the aircraft

Among them, k′ _{_α_i} <k _{_α_i-1} , when i=1, k′ _{_α_1} = _kinit , _kinit is the initial value of the angle of attack descending slope, and _kinit≥0 .

步骤S207：比较所述第i首个法向过载峰值

和所述期望的法向过载动平衡的波动区域[N_{n_want}±ΔN_n]，根据比较结果对设计攻角的下降斜率k′_{_α_i}进行调整，直到所述第i首个法向过载峰值处于所述期望的法向过载动平衡的波动区域[N_{n_want}±ΔN_n]内，并确定此时对应的设计攻角下降斜率k_{_α_i}。Step S207: Comparing the ith first normal overload peak value

and the fluctuation area [N _{n_want} ±ΔN _n ] of the expected normal overload dynamic balance, adjust the descending slope k′ _{_α_i} of the design angle of attack according to the comparison result until the ith first normal overload peak value It is within the fluctuation region [N _{n_want} ±ΔN _n ] of the expected normal overload dynamic balance, and the corresponding design angle of attack descending slope k _{_α_i} is determined at this time.

其中，所述根据比较结果对设计攻角的下降斜率k′_{_α_i}进行调整，具体为：Wherein, the descending slope _{k′_α_i} of the design angle of attack is adjusted according to the comparison result, specifically:

若说明法向过载N_n过大，增大设计攻角的下降斜率k′_{_α_i}；若

需要减小设计攻角的下降斜率k′_{_α_i}。like It shows that the normal overload N _n is too large, increase the descending slope k′ _{_α_i} of the design angle of attack; if

It is necessary to reduce the descending slope k′ _{_α_i} of the design angle of attack.

具体的设计攻角的下降斜率k′_{_α_i}的调整方式可以为：对所述设计攻角的下降斜率k′_{_α_i}增加或减少一个预设的调整量Δk_{_α}。所述调整量Δk_{_α}可以根据实际需要具体设定，例如设定调整量Δk_{_α}为攻角下降斜率初始值k_init的1％至3％。A specific way to adjust the descending slope k′ _{_α_i} of the design angle of attack may be: increase or decrease a preset adjustment amount Δk _{_α} to the descending slope k′ _{_α_i} of the design angle of attack. The adjustment amount _{Δk_α} can be specifically set according to actual needs, for example, the adjustment amount _{Δk_α} is set to be 1% to 3% of the initial value _kinit of the angle of attack descending slope.

步骤S208：利用飞行器同态预测模型，预测以t_{i_α}时刻飞行器的飞行状态为所述同态预测模型的初始状态、以α_i-1-k_{_α_i}(t-t_{i_α})为设计攻角α进行再入飞行时，飞行器的法向过载N_n经过所述第i首个法向过载峰值后、脱离所述期望的法向过载动平衡的波动区域[N_{n_want}±ΔN_n]的时刻t_{i+1_α}。Step S208: Using the aircraft homomorphic prediction model, predict the flight state of the aircraft at time t _{i_α} as the initial state of the homomorphic prediction model, and use α _i-1 -k _{_α_i} (tt _{i_α} ) as the design angle of attack α for reentry During flight, the normal overload _N of the aircraft passes through the ith first normal overload peak value Afterwards, time t _{i+1_α} departing from the expected normal overload dynamic balance fluctuation region [N _{n_want} ±ΔN _n ].

结合步骤S206至步骤S208可知，在[t_{i_α}，t_{i+1_α}]时间段内，在飞行器再入飞行模型运行至t_{i_α}时刻时，法向过载N_n是处于所述期望的法向过载动平衡的波动区域[N_{n_want}±ΔN_n]内的；而且时刻t_{i+1_α}是指飞行器的法向过载N_n经过所述第i首个法向过载峰值

后、脱离所述期望的法向过载动平衡的波动区域[N_{n_want}±ΔN_n]的时刻；同时，在[t_{i_α}，t_{i+1_α}]时间段内，通过对其设计攻角的设定，可以使得其法向过载峰值

处于所述期望的法向过载动平衡的波动区域[N_{n_want}±ΔN_n]内。因此，可知，在整个[t_{i_α}，t_{i+1_α}]时间段，飞行器的法向过载值始终是处于期望的法向过载动平衡的波动区域[N_{n_want}±ΔN_n]内的，达到了在[t_{i_α}，t_{i+1_α}]时间段内飞行器再入飞行法向过载动平衡的目的。Combining steps S206 to S208, it can be seen that within the time period [t _{i_α} , t _{i+1_α} ], when the aircraft re-entry flight model runs to the time t _{i_α} , the normal overload N _n is at the desired normal overload dynamic within the balanced fluctuation region [N _{n_want} ±ΔN _n ]; and the moment t _{i+1_α} means that the normal overload N _n of the aircraft passes the ith first normal overload peak value

Afterwards, the moment when it departs from the fluctuation region [N _{n_want} ±ΔN _n ] of the expected normal overload dynamic balance; at the same time, within the time period [t _{i_α} , t _{i+1_α} ], by setting the design angle of attack , which can make its normal overload peak

It is within the fluctuation region [N _{n_want} ±ΔN _n ] of the desired normal overload dynamic balance. Therefore, it can be seen that during the entire [t _{i_α} , t _{i+1_α} ] time period, the normal overload value of the aircraft is always within the fluctuation region [N _{n_want} ±ΔN _n ] of the expected normal overload dynamic balance, reaching the [t _{i_α} , t _{i+1_α} ] The purpose of the aircraft re-entry flight normal overload dynamic balance.

优选地，所述方法还包括：当i大于等于2时，对t_{i+1_α}的更新，具体为：Preferably, the method further includes: when i is greater than or equal to 2, updating t _{i+1_α} , specifically:

在[t_{i_α}，t_{i+1_α}]时间段内，不断的以飞行器不断的以飞行器当前在再入飞行模型中的飞行状态作为同态预测模型的初始状态，预测从当前时刻开始、以α_i-1-k_{_α_i}(t-t_{i_α})为设计攻角α进行再入飞行时，飞行器的法向过载N_n经过所述第i首个法向过载峰值

后、脱离所述期望的法向过载动平衡的波动区域[N_{n_want}±Δ_N]的时刻t′_{i+1_α}，以t′_{i+1_α}作为更新后的t_{i+1_α}。During the time period [t _{i_α} , t _{i+1_α} ] _, the aircraft continuously takes the current flight state of the aircraft in the re-entry flight model as the initial state of the homomorphic prediction model. _-1 -k _{_α_i} (tt _{i_α} ) is the design angle of attack α during re-entry flight, the normal overload N _n of the aircraft passes through the ith first normal overload peak value

Afterwards, at the moment t′ _{i+1_α} when the fluctuation region [N _{n_want} ±Δ _N ] departs from the expected normal overload dynamic balance, take t′ _{i+1_α} as the updated t _{i+1_α} .

步骤S209：设定[t_{i_α}，t_{i+1_α}]时间段内，设计攻角α为α_i-1-k_{_α_i}(t-t_{i_α})。Step S209: Set the design angle of attack α to be α _i-1 -k _{_α_i} (tt _{i_α} ) within the time period [t _{i_α} , t _i+ 1_α ].

步骤S210：当所述下降斜率k_{_α_i}小于等于预设的k₀时，飞行器的法向过载动平衡结束，结束流程；否则，i加1，返回步骤S206。Step S210: When the descending slope k _{_α_i} is less than or equal to the preset k ₀ , the normal overload dynamic balance of the aircraft ends, and the process ends; otherwise, add 1 to i, and return to step S206.

所述预设k₀为一较小值。具体的，可以设定k₀等于步骤S207中所述调整量Δk_{_α}的1至2倍。The preset k ₀ is a small value. Specifically, k ₀ may be set equal to 1 to 2 times the adjustment amount Δk _{_α} in step S207.

综上所述，本发明实施例中，所得到的飞行器法向过载动平衡条件下的各飞行时刻的再入攻角设计预测值

为：To sum up, in the embodiment of the present invention, the obtained re-entry attack angle design prediction value at each flight time under the condition of aircraft normal overload dynamic balance

for:

${\overset{~ ~}{α α}}_{des des} = = [\begin{matrix} {α α}_{init init} & {t t}_{init init} \leq \leq t t \leq \leq {t t}_{11__α α} \\ \cdot &Center Dot; \\ \cdot &Center Dot; \\ \cdot &Center Dot; \\ {α α}_{i i - - 11} - - {k k}_{__α α__i i} ((t t - - {t t}_{i i__α α})) & {t t}_{i i__α α} < < t t \leq \leq {t t}_{i i + + 11__α α} \\ \cdot &Center Dot; \\ \cdot \cdot \\ \cdot &Center Dot; \\ {α α}_{N N - - 11} - - {k k}_{__α α__N N} ((t t - - {t t}_{N N__α α})) & {t t}_{N N - - 11__α α} < < t t \leq \leq {t t}_{end end} \end{matrix}] - - - - - - ((1616))$

本发明实施例提供的第一种获取再入攻角设计预测值

的实施方式中，分时间段对设计攻角α的取值进行设定。对于每一时间段，利用飞行器同态预测模型，找到使得飞行器的法向过载值始终处于期望的法向过载动平衡的波动区域内的设计攻角值，实现该时间段内的法向过载动态平衡。The first method to obtain the design prediction value of the re-entry angle of attack provided by the embodiment of the present invention

In the embodiment, the value of the design angle of attack α is set according to time periods. For each time period, use the homomorphic prediction model of the aircraft to find the design angle of attack value that makes the normal overload value of the aircraft always in the fluctuation region of the expected normal overload dynamic balance, and realize the normal overload dynamics in this time period balance.

与现有技术中采用唯一固定的攻角调整下降斜率相比，能够使得各时间段内的法向过载在期望的波动区域内小幅度波动，使得法向过载由单/双峰变为平峰，实现了各时间段内的法向过载动平衡，达到降低飞行器再入过程中的法向过载峰值的目的。Compared with the use of a unique fixed angle of attack to adjust the descending slope in the prior art, the normal overload in each time period can be made to fluctuate in a small range within the expected fluctuation range, so that the normal overload changes from a single/double peak to a flat peak, The dynamic balance of the normal overload in each time period is realized, and the purpose of reducing the peak value of the normal overload during the reentry process of the aircraft is achieved.

优选地，上述方法中，当且仅当i＝1时，还可以包括：设定调整时间提前量为Δt_α，在[t_init，（t_{1_α}-Δt_α)]时间段内，飞行器再入飞行的设计攻角α等于初始值α_init；Preferably, in the above method, if and only when i=1, it may also include: setting the adjustment timing advance as Δt _α , and within the time period [t _init , (t _{1_α} -Δt _α )], the aircraft re-entry The flight design angle of attack α is equal to the initial value α _init ;

当飞行器再入飞行模型运行至t_{1_α}-Δt_α时刻时，利用飞行器同态预测模型，预测以飞行器t_{1_α}-Δt_α时刻的飞行状态为所述同态预测模型的初始状态、以α₀-k′_{_α_1}(t-t_{1_α}+Δt_α)为设计攻角α进行再入飞行时，飞行器的第一首个法向过载峰值

When the aircraft re-entry flight model runs to the time t _{1_α} -Δt _α , the homomorphic prediction model of the aircraft is used to predict the flight state of the aircraft at the time t _{1_α} -Δt _α as the initial state of the homomorphic prediction model, and α ₀ - k′ _{_α_1} (tt _{1_α} +Δt _α ) is the first normal overload peak value of the aircraft during reentry flight at the design angle of attack α

比较所述第一首个法向过载峰值

和所述期望的法向过载动平衡的波动区域[Nn_{_want}±ΔN_n]，根据比较结果对设计攻角的下降斜率k_{_α}进行调整，直到所述第一首个法向过载峰值

处于所述期望的法向过载动平衡的波动区域[N_{n_want}±ΔN_n]内，并确定此时对应的设计攻角下降斜率k_{_α_1}；Compare the first normal overload peak value with the first

and the fluctuation region [Nn _{_want} ±ΔN _n ] of the expected normal overload dynamic balance, adjust the descending slope k _{_α} of the design angle of attack according to the comparison result until the first normal overload peak

Be in the fluctuation region [N _{n_want} ±ΔN _n ] of the expected normal overload dynamic balance, and determine the corresponding design angle of attack descending slope k _{_α_1} at this time;

利用飞行器同态预测模型，预测以t_{1_α}-Δt_α时刻飞行器的飞行状态为所述同态预测模型的初始状态、以α_init-k_{_α_1}(t-t_{1_α}+Δt_α)为设计攻角α进行再入飞行时，飞行器的法向过载N_n经过所述第一首个法向过载峰值后、脱离所述期望的法向过载动平衡的波动区域[N_{n_want}±ΔN_n]的时刻t_{2_α}；Using the homomorphic prediction model of the aircraft, it is predicted that the flight state of the aircraft at time t _{1_α} -Δt _α is the initial state of the homomorphic prediction model, and α _init -k _{_α_1} (tt _{1_α} +Δt _α ) is the design angle of attack α for further When entering the flight, the normal overload _N of the aircraft passes through the first first normal overload peak value Afterwards, the moment t _{2_α} when departing from the fluctuation region [N _{n_want} ±ΔN _n ] of the expected normal overload dynamic balance;

优选地，所述方法还包括：当i＝1时，对t_{1_α}的更新，具体为：Preferably, the method further includes: when i=1, updating t _{1_α} , specifically:

第二种实施方式：The second implementation mode:

本发明实施例提供的第二种获取再入攻角设计预测值

方法可以包括以下步骤：The second method of obtaining the design prediction value of the re-entry angle of attack provided by the embodiment of the present invention

The method may include the steps of:

步骤S301：选取设计攻角α的初始值α_init，以初始值α_init所对应的时刻t_init为起始时刻。Step S301: Select the initial value α _init of the design angle of attack α, and take the time t _init corresponding to the initial value α _init as the starting time.

步骤S302：建立飞行器再入飞行模型以及飞行器再入飞行的同态预测模型，利用再入飞行模型模拟飞行器的再入飞行状态，再入飞行模型以时间为变量进行计算。所述再入飞行模型和预测模型的初始状态为攻角设计起始时刻t_init对应的飞行器状态。Step S302: Establishing the re-entry flight model of the aircraft and the homomorphic prediction model of the re-entry flight of the aircraft, using the re-entry flight model to simulate the re-entry flight state of the aircraft, and calculating the re-entry flight model with time as a variable. The initial state of the re-entry flight model and the prediction model is the state of the aircraft corresponding to the initial time t _init of the angle of attack design.

步骤S303：设定法向过载动平衡的期望中值N_{n_want}和法向过载波动限制值ΔN_n，则期望的法向过载动平衡的波动区域为[N_{n_want}±ΔN_n]。Step S303: Set the expected median value N _{n_want} of the normal overload dynamic balance and the normal overload fluctuation limit value ΔN _n , then the expected fluctuation range of the normal overload dynamic balance is [N _{n_want} ±ΔN _n ].

步骤S304：利用飞行器同态预测模型，预测从起始时刻t_init开始、以初始值α_init为设计攻角α进行再入飞行，达到法向过载N_n大于等于法向过载动平衡的期望中值N_{n_want}的时刻t_{1_α}。Step S304: Using the homomorphic prediction model of the aircraft, it is predicted that the re-entry flight will start from the initial time t _init and take the initial value α _init as the design angle of attack α to achieve the expected normal overload N _n greater than or equal to the normal overload dynamic balance Time t _{1_α} of value N _{n_want} .

步骤S305：设定调整时间提前量为Δt_α，在t_init≤t≤(t_{1_α}-Δt_α)内，飞行器再入飞行的设计攻角α等于初始值α_init。Step S305: Set the adjustment timing advance amount to Δt _α , and within t _init ≤t ≤ (t _{1_α} -Δt _α ), the design attack angle α of the reentry flight of the aircraft is equal to the initial value α _init .

即为，在[t_init，(t_{1_α}-Δ_tα)]时间段内，设计攻角α等于初始值α_init。That is, within the time period [t _init , (t _{1_α} -Δ _tα )], the design angle of attack α is equal to the initial value α _init .

由于具体实现中，对于攻角的控制过程具有一定的延迟，因此需要在时间上保留一定的调整余地，故设定调整时间提前量为Δt_α。Since there is a certain delay in the control process of the angle of attack in the specific implementation, it is necessary to reserve a certain room for adjustment in time, so the adjustment time advance is set as Δt _α .

优选地，飞行器的再入飞行过程中，由于受到风力的作用、大气不均与的影响，可能使得飞行器实际从初始时刻t_init起、达到法向过载N_n大于等于法向过载动平衡的期望中值N_{n_want}的时刻与步骤S304中得到的预测值t_{1_α}是存在误差的。Preferably, during the re-entry flight of the aircraft, due to the effect of wind force and the influence of atmospheric inhomogeneity, the aircraft may actually reach the expectation of normal overload N _n being greater than or equal to the normal overload dynamic balance from the initial time t _init There is an error between the moment of the median N _{n_want} and the predicted value t _{1_α} obtained in step S304.

因此，本发明实施例所述方法，还进一步包括对所述预测值t_{1_α}的更新过程。具体的，Therefore, the method described in the embodiment of the present invention further includes an update process of the predicted value t _{1_α} . specific,

在t_init≤t≤(t_{1_α}-Δt_α)内，可以不断的以飞行器当前在再入飞行模型中的飞行状态作为同态预测模型的初始状态，预测从当前时刻开始、以初始值α_init为设计攻角α进行再入飞行，达到法向过载N_n大于等于法向过载动平衡的期望中值N_{n_want}的时刻t′_{1_α}；用t′_{1_α}更新步骤S305所述t_init≤t≤(t_{1_α}-Δt_α)中的t_{1_α}。Within t _init ≤t≤(t _{1_α} -Δt _α ), the current flight state of the aircraft in the re-entry flight model can be continuously used as the initial state of the homomorphic prediction model, and the prediction starts from the current moment with the initial value α _init To design the angle of attack α to carry out re-entry flight, to reach the moment t′ _{1_α} at which the normal overload N _n is greater than or equal to the expected median value N _{n_want} of the normal overload dynamic balance; use t′ _{1_α} to update the t _init ≤ t ≤ ( t _{1_α} in t _{1_α} -Δt _α ).

步骤S306：当飞行器再入飞行模型运行至t_{1_α}-Δt_α时刻时，利用飞行器同态预测模型，预测以飞行器当前的飞行状态为所述同态预测模型的初始状态、以α_init-k_init(t-t₁__α+Δt_α)为设计攻角α进行再入飞行时，飞行器的第一首个法向过载峰值

其中，k_init攻角下降斜率k_{_α}的初始值，k_init≥0。Step S306: When the aircraft re-entry flight model runs to the time t _{1_α} -Δt _α , use the aircraft homomorphic prediction model to predict the current flight state of the aircraft as the initial state of the homomorphic prediction model, and use α _init -k _init (tt ₁ _ _α +Δt _α ) is the first normal overload peak of the aircraft during reentry flight at the design angle of attack α

Among them, _kinit is the initial value of the angle of attack descending slope _{k_α} , _kinit ≥ 0.

具体的，攻角下降斜率k_{_α}的初始值为k_init可以根据经验具体设定。Specifically, the initial value of the angle-of-attack descending slope k _{_α} _{is kinit,} which can be specifically set according to experience.

步骤S307：比较所述第一首个法向过载峰值

和所述期望的法向过载动平衡的波动区域[N_{n_want}±ΔN_n]，根据比较结果对设计攻角的下降斜率k_{_α}进行调整。Step S307: Comparing the first first normal overload peak value

and the expected fluctuation region [N _{n_want} ±ΔN _n ] of the normal overload dynamic balance, adjust the descending slope k _{_α} of the design angle of attack according to the comparison result.

具体的，所述对设计攻角的下降斜率k_{_α}进行调整可以为：Specifically, the adjustment to the descending slope _{k_α} of the design angle of attack can be:

若

说明法向过载N_n过大，需要增大设计攻角的下降斜率k_{_α}；若

需要减小设计攻角的下降斜率k_{_α}。like

It shows that the normal overload N _n is too large, it is necessary to increase the descending slope _{k_α} of the design angle of attack; if

It is necessary to reduce the descending slope k _{_α} of the design angle of attack.

具体的，设计攻角的下降斜率k_{_α}的调整方式可以为：增加或减少一个预设的调整量Δk_{_α}。所述调整量Δk_{_α}可以根据实际需要具体设定，例如设定调整量Δk_{_α}为攻角下降斜率初始值k_init的1％至3％。Specifically, the method of adjusting the descending slope k _{_α} of the design angle of attack may be: increase or decrease a preset adjustment amount Δk _{_α} . The adjustment amount _{Δk_α} can be specifically set according to actual needs, for example, the adjustment amount _{Δk_α} is set to be 1% to 3% of the initial value _kinit of the angle of attack descending slope.

步骤S308：用调整后的下降斜率k_{_α}替换步骤S306中所述α_init-k_init(t-t_{1_α}+Δt_α)中的k_init，重复步骤S306至步骤S308，直到所述第一首个法向过载峰值

处于所述期望的法向过载动平衡的波动区域[N_{n_want}±ΔN_n]内，并确定此时对应的设计攻角下降斜率k_{_α_1}。Step S308: Replace the kinit in α _init _-kinit (tt _{1_α} +Δt _α ) in step _S306 with the adjusted descending slope k _{_α} , and repeat steps S306 to S308 until the first normal direction overload peak

It is within the fluctuation region [N _{n_want} ±ΔN _n ] of the expected normal overload dynamic balance, and the corresponding design angle of attack descending slope k _{_α_1} is determined at this time.

步骤S309：利用飞行器同态预测模型，预测以t_{1_α}-Δ_α时刻飞行器的飞行状态为所述同态预测模型的初始状态、以α_init-k_{_α_1}(t-t_{1_α}+Δt_α)为设计攻角α进行再入飞行时，飞行器的法向过载N_n经过所述第一首个法向过载峰值后、脱离所述期望的法向过载动平衡的波动区域[N_{n_want}±ΔN_n]的时刻t_{2_α}。Step S309: Using the homomorphic prediction model of the aircraft, predict that the flight state of the aircraft at time t _{1_α} -Δ _α is the initial state of the homomorphic prediction model, and α _init -k _{_α_1} (tt _{1_α} +Δt _α ) is the design angle of attack When α is performing re-entry flight, the normal overload N _n of the aircraft passes through the first first normal overload peak value Afterwards, the time t _{2_α} when departing from the fluctuation region [N _{n_want} ±ΔN _n ] of the expected normal overload dynamic balance.

即为，在[t_{1_α}-Δt_α，t_{2_α}]时间段内，设计攻角α为α_init-k_{_α_1}(t-t_{1_α}+Δt_α)。That is, within the time period [t _{1_α} -Δt _α , t _{2_α} ], the design angle of attack α is α _init -k _{_α_1} (tt _{1_α} +Δt _α ).

优选地，还可以包括对所述预测值t_{2_α}的更新过程。具体为：Preferably, an update process for the predicted value t _{2_α} may also be included. Specifically:

在[t_{1_α}-Δt_α，t_{2_α}]内，可以不断的以飞行器当前在再入飞行模型中的飞行状态作为同态预测模型的初始状态，预测从当前时刻开始、以α_inik-k_{_α_1}(t-t_{1_α}+Δt_α)为设计攻角α进行再入飞行，飞行器的法向过载N_n经过所述第一首个法向过载峰值

后、脱离所述期望的法向过载动平衡的波动区域[N_{n_want}±ΔN_n]的时刻t′_{2_α}；用t′_{2_α}更新步骤S309所述[t_{1_α}-Δt_α，t_{2_α}]中的t_{2_α}。Within [t _{1_α} -Δt _α , t _{2_α} ], the current flight state of the aircraft in the re-entry flight model can be continuously used as the initial state of the homomorphic prediction model, and the prediction starts from the current moment with α _inik -k _{_α_1} ( tt _{1_α} +Δt _α ) is the design angle of attack α for re-entry flight, the normal overload N _n of the aircraft passes through the first first normal overload peak

Afterwards, the moment t′ _{2_α} departing from the fluctuation region [N _{n_want} ±ΔN _n ] of the expected normal overload dynamic balance; use t′ _{2_α} to update the t in [t _{1_α} -Δt _α , t _{2_α} ] described in step S309 _{2_α} .

步骤S310：获取飞行器再入飞行至t_{2_α}时刻的实际攻角值α₁，利用飞行器同态预测模型，预测以飞行器t_{2_α}时刻的飞行状态为所述同态预测模型的初始状态、以α₁-k′_{_α_2}(t-t_{2_α})为设计攻角α进行再入飞行时，飞行器的第二首个法向过载峰值

其中，k′_{_α_2}小于k_{_α_1}。采用与步骤S307至S308中相同的方法，对k′_{_α_2}进行调整，确定所述第二首个法向过载峰值

处于所述期望的法向过载动平衡的波动区域[N_{n_want}±ΔN_n]内时对应的下降斜率k_{_α_2}，采用与步骤S309相同的方法，获得飞行器的法向过载N_n经过所述第二首个法向过载峰值

后、脱离所述期望的法向过载动平衡的波动区域[N_{n_want}±ΔN_n]的时刻t_{3_α}。Step S310: Obtain the actual angle of attack value α ₁ of the aircraft re-entry flight to the time t _{2_α} , and use the aircraft homomorphic prediction model to predict the flight state of the aircraft at the time t _{2_α} as the initial state of the homomorphic prediction model, with α ₁ -k′ _{_α_2} (tt _{2_α} ) is the second first normal overload peak value of the aircraft during reentry flight at the design angle of attack α

Among them, k′ _{_α_2} is smaller than k _{_α_1} . Using the same method as in steps S307 to S308, _{k'_α_2} is adjusted to determine the second first normal overload peak value

When it is in the expected normal overload dynamic balance fluctuation region [N _{n_want} ±ΔN _n ], the corresponding descending slope k _{_α_2} , using the same method as step S309, obtains the normal overload N _n of the aircraft passing through the second First normal overload peak

Afterwards, time t _{3_α} departing from the expected normal overload dynamic balance fluctuation region [N _{n_want} ±ΔN _n ].

即为，在[t_{2_α}，t_{3_α}]时间段内，设计攻角α为α₁-k_{_α_2}(t-t_{2_α})。That is, in the time period [t _{2_α} , t _{3_α} ], the design angle of attack α is α ₁ -k _{_α_2} (tt _{2_α} ).

优选地，还可以包括对所述预测值t_{3_α}的更新过程。具体为：Preferably, an update process for the predicted value t _{3_α} may also be included. Specifically:

在[t_{2_α}，t_{3_α}]内，可以不断的以飞行器当前在再入飞行模型中的飞行状态作为同态预测模型的初始状态，预测从当前时刻开始、以α₁-k′_{_α_2}(t-t_{2_α})为设计攻角α进行再入飞行，飞行器的法向过载N_n经过所述第二首个法向过载峰值

后、脱离所述期望的法向过载动平衡的波动区域[N_{n_want}±ΔN_n]的时刻t′_{3_α}；用t′_{3_α}更新步骤S310所述[t_{2_α}，t_{3_α}]中的t_{3_α}。In [t _{2_α} , t _{3_α} ], the current flight state of the aircraft in the re-entry flight model can be continuously used as the initial state of the homomorphic prediction model, and the prediction starts from the current moment with α ₁ -k′ _{_α_2} (tt _{2_α} ) is the design angle of attack α for re-entry flight, the normal overload N _n of the aircraft passes through the second first normal overload peak value

Afterwards, the moment t′ _{3_α} departing from the fluctuation region [N _{n_want} ±ΔN _n ] of the expected normal overload dynamic balance; use t′ _{3_α} to update t _{3_α} in [t _{2_α} , t _{3_α} ] in step S310.

步骤S311：以此类推，重复步骤S310，获取飞行器再入飞行模型运行至t_{N_α}时刻的模拟攻角值α_N-1，利用飞行器同态预测模型，预测以飞行器t_{N_α}时刻的飞行状态为所述同态预测模型的初始状态、以α_N-1-k′_{_α_N}(t-t_{N_α})为设计攻角α进行再入飞行时，第N首个法向过载峰值

其中，k′_{_α_N}小于k_{_α_N-1}；获取所述第N首个法向过载峰值

处于所述期望的法向过载动平衡的波动区域[N_{n_want}±ΔN_n]内时对应的下降斜率k_{_α_N}，以及飞行器的法向过载N_n经过所述第N首个法向过载峰值后、脱离所述期望的法向过载动平衡的波动区域[N_{n_want}±ΔN_n]的时刻t_{N+1_α}。Step S311: By analogy, repeat step S310, obtain the simulated angle of attack value α _N-1 of the aircraft re-entry flight model running to the time t _{N_α} , and use the aircraft homomorphic prediction model to predict the flight state of the aircraft at the time t _{N_α} In the initial state of the homomorphic prediction model, when α _N-1 -k′ _{_α_N} (tt _{N_α} ) is the design angle of attack α for reentry flight, the Nth first normal overload peak

Wherein, k′ _{_α_N} is less than k _{_α_N-1} ; Obtain the N first normal overload peak value

The corresponding descending slope k _{_α_N} when it is in the fluctuation region [N _{n_want} ±ΔN _n ] of the expected normal overload dynamic balance, and after the normal overload N _n of the aircraft passes through the Nth first normal overload peak value, The moment t _{N+1_α} at which the desired normal overload dynamic balance is out of the fluctuation range [N _{n_want} ±ΔN _n ].

即为，在[t_{N_α}，t_{N+1_α}]时间段内，设计攻角α为α_N-1-k_{_α_N}(t-t_{N_α})。That is, within the time period [t _{N_α} , t _{N+1_α} ], the design angle of attack α is α _N-1 -k _{_α_N} (tt _{N_α} ).

优选地，还可以包括对所述预测值t_{N+1_α}的更新过程。具体为：Preferably, an update process for the predicted value t _{N+1_α} may also be included. Specifically:

在[t_{N_α}，t_{N+1_α}]内，可以不断的以飞行器当前在再入飞行模型中的飞行状态作为同态预测模型的初始状态，预测从当前时刻开始、以α_N-1-k′_{_α_N}(t-t_{N_α})为设计攻角α进行再入飞行，飞行器的法向过载N_n经过所述第N首个法向过载峰值后、脱离所述期望的法向过载动平衡的波动区域[N_{n_want}±ΔN_n]的时刻t′_{N+1_α}；用t′_{N+1_α}更新步骤S311所述[t_{N_α}，t_{N+1_α}]中的t_{N+1_α}。In [t _{N_α} , t _{N+1_α} ], the current flight state of the aircraft in the re-entry flight model can be continuously used as the initial state of the homomorphic prediction model, and the prediction starts from the current moment, with α _N-1 -k′ _{_α_N} (tt _{N_α} ) is the design angle of attack α for re-entry flight, and the normal overload N _n of the aircraft passes through the Nth first normal overload peak Afterwards, the moment t′ _{N+1_α} departing from the fluctuation region [N _{n_want} ±ΔN _n ] of the expected normal overload dynamic balance; use t′ _{N+1_α} to update [t _{N_α} , t _{N+1_α} ] in step S311 t _{N+1_α} in .

步骤S312：当所述α_N-1-k_{_α_N}(t-t_{N_α})中的下降斜率k_{_α_N}小于等于预设的k₀时，飞行器的法向过载动平衡结束，跳出步骤S311，结束流程；将时刻t_{N+1_α}作为动平衡的结束时刻t_end。Step S312: When the descending slope k _{_α_N} in the α _N-1 -k _{_α_N} (tt _{N_α} ) is less than or equal to the preset k ₀ , the normal overload dynamic balance of the aircraft ends, step S311 is skipped, and the process ends; t _{N+1_α} is used as the end time t _end of the dynamic balance.

所述预设k₀为一较小值。具体的，可以设定k₀等于步骤S307中所述调整量Δk_{_α}的1至2倍。The preset k ₀ is a small value. Specifically, k ₀ may be set equal to 1 to 2 times the adjustment amount Δk _{_α} in step S307.

综上所述，本发明实施例中，由第二种再入攻角设计预测值

获取方法所得到的飞行器法向过载动平衡条件下的各飞行时刻的再入攻角设计预测值

为：In summary, in the embodiment of the present invention, the predicted value is designed by the second re-entry angle of attack

The design prediction value of the re-entry angle of attack at each flight time under the condition of normal overload dynamic balance of the aircraft obtained by the acquisition method

for:

${\overset{~ ~}{α α}}_{des des} = = \{\begin{matrix} {α α}_{init init} & {t t}_{init init} \leq \leq t t \leq \leq (({t t}_{11__α α} - - {Δt Δt}_{α α})) \\ {α α}_{init init} - - {k k}_{__α α__11} ((t t - - {t t}_{11__α α} + + {Δt Δt}_{α α})) & (({t t}_{11__α α} - - {Δt Δt}_{α α})) < < t t \leq \leq {t t}_{22__α α} \\ {α α}_{11} - - {k k}_{__α α__22} ((t t - - {t t}_{22__α α})) & {t t}_{22__α α} < < t t \leq \leq {t t}_{33__α α} \\ \cdot &Center Dot; \\ \cdot &Center Dot; \\ \cdot &Center Dot; \\ {α α}_{N N - - 11} - - {k k}_{__α α__N N} ((t t - - {t t}_{N N__α α})) & {t t}_{N N - - 11__α α} < < t t \leq \leq {t t}_{end end} \end{matrix} - - - - - - ((1717))$

本发明实施例中提供的第二种再入攻角设计预测值

获取方法中，分时间段对设计攻角α的取值进行设定。对于每一时间段，利用飞行器同态预测模型，找到使得飞行器的法向过载值始终处于期望的法向过载动平衡的波动区域内的设计攻角值，实现该时间段内的法向过载动态平衡。The second type of re-entry angle of attack design prediction value provided in the embodiment of the present invention

In the acquisition method, the value of the design angle of attack α is set in time periods. For each time period, use the homomorphic prediction model of the aircraft to find the design angle of attack value that makes the normal overload value of the aircraft always in the fluctuation region of the expected normal overload dynamic balance, and realize the normal overload dynamics in this time period balance.

需要说明的是，在亚轨道飞行器的再入飞行中，影响其法向过载的因素不仅仅是攻角，还有速度倾侧角。所述速度倾侧角不改变飞行器所受气动力大小，但是可以可变飞行器所受气动力的方向。当速度倾侧角不为零时，飞行器所受气动力的方向发生改变，将加快飞行器的下降速度，导致飞行器的法向过载进一步增大。It should be noted that, in the reentry flight of a suborbital vehicle, the factors affecting its normal overload are not only the angle of attack, but also the velocity roll angle. The speed roll angle does not change the magnitude of the aerodynamic force received by the aircraft, but can change the direction of the aerodynamic force received by the aircraft. When the velocity roll angle is not zero, the direction of the aerodynamic force on the aircraft will change, which will accelerate the descent speed of the aircraft, resulting in a further increase in the normal overload of the aircraft.

对于本发明实施例所述的飞行器再入飞行过程中的设计攻角的获取方法，当不需要考虑速度倾侧角时，只需设定步骤S202和S302中所述飞行器同态预测模型中对应的飞行器速度倾侧角σ为0；当需要同时考虑速度倾侧角和攻角时，需要预先制定各时刻的速度倾侧角的设计值，使步骤S202和S302中所述飞行器同态预测模型中的速度倾侧角σ为各对应时刻的速度倾侧角设计值即可。For the acquisition method of the design angle of attack during the aircraft re-entry flight described in the embodiment of the present invention, when the speed roll angle does not need to be considered, it is only necessary to set the corresponding The speed roll angle σ of the aircraft is 0; when the speed roll angle and the attack angle need to be considered at the same time, it is necessary to pre-determine the design value of the speed roll angle at each moment, so that the speed roll in the aircraft homomorphic prediction model described in steps S202 and S302 The angle σ is only the design value of the velocity roll angle at each corresponding moment.

本发明实施例中，在飞行器的再入飞行之前，获取了实现法向过载动平衡的再入攻角的设计值，并以该设计值通过最小二乘方法得到攻角设计系数b₁、b₂、b₃、b₄，由此得到的式(5)所示攻角表达下的攻角设计值能够实现法向过载动态平衡。在飞行器再入飞行过程中，引入的修正参数η(t)是随时间变化的积分比值，比值的分子为阻力加速度预测值在当前时刻t之前的积分值

比值的分母为阻力加速度实际测量值D(t)在当前时刻t之前的积分值

当阻力加速度预测值

的积分与阻力加速度实际测量值D(t)的积分

趋同时，说明实际飞行的飞行状态正与在设计攻角下得预测飞行状态趋同。从式(13)可见，当修正系数η(t)＝1，则攻角制导值α_cmd(t)等于攻角设计值α_des(t)，此时阻力加速度预测值

在当前时刻t之前的积分值等于阻力加速度实际测量值D(t)在当前时刻t之前的积分值

当修正系数η(t)不为1时，攻角制导值α_cmd(t)将在攻角设计值α_des(t)进行调整，使得

与

趋同。In the embodiment of the present invention, before the re-entry flight of the aircraft, the design value of the re-entry attack angle to realize the normal overload dynamic balance is obtained, and the design value of the attack angle design coefficient b ₁ , b is obtained by the least square method ₂ , b ₃ , b ₄ , the design value of the angle of attack expressed in formula (5) can realize the dynamic balance of normal overload. During the re-entry flight of the aircraft, the introduced correction parameter η(t) is the integral ratio that changes with time, and the numerator of the ratio is the predicted value of drag acceleration The integral value before the current time t

The denominator of the ratio is the integral value of the actual measured resistance acceleration D(t) before the current time t

When the drag acceleration prediction value

points Integral with the actual measured value D(t) of drag acceleration

When converging, it means that the flight state of the actual flight is converging with the predicted flight state at the design angle of attack. It can be seen from formula (13) that when the correction coefficient η(t)=1, the angle-of-attack guidance value α _cmd (t) is equal to the design value α _des (t) of the attack angle, and the predicted value of drag acceleration at this time

The integral value before the current time t Equal to the integral value of the actual measurement value D(t) of resistance acceleration before the current time t

When the correction coefficient η(t) is not 1, the angle-of-attack guidance value α _cmd (t) will be adjusted at the design value α _des (t) of the angle of attack, so that

and

converge.

下面结合采用本发明所述方法对亚轨道飞行器进行仿真实验得到的结果，进一步说明本发明实施例实现的目的。The purpose achieved by the embodiment of the present invention will be further described below in combination with the results obtained from the simulation experiment of the suborbital vehicle using the method of the present invention.

仿真实验中，设定：In the simulation experiment, set:

飞行器的再入初始高度(即为峰点高度)H＝148km，飞行器在所述再入初始高度时对应的速度V＝2133.5m/s。The initial re-entry altitude of the aircraft (ie, the height of the peak point) H=148km, and the corresponding velocity V of the aircraft at the initial re-entry altitude=2133.5m/s.

飞行器再入飞行过程中的速度峰值为2415m/s，该速度峰值对应的飞行高度为47.691km。The peak speed of the aircraft during the reentry flight is 2415m/s, and the flight altitude corresponding to the peak speed is 47.691km.

首先将说明本发明的设计攻角值的获取方法的效果。First, the effect of the acquisition method of the design angle of attack value of the present invention will be described.

从飞行器达到所述速度峰值开始，以法向过载动态平衡为目的，对攻角进行设计，设定所述法向过载动平衡的期望中值N_{n_want}＝4.99，法向过载波动限制值ΔN_n＝0.005，设计攻角α的初始值α_init＝40°，速度倾侧角初始为零，在飞行速度衰减足够后加入。From the time when the aircraft reaches the peak speed, the angle of attack is designed for the purpose of normal overload dynamic balance, and the expected median value N _{n_want} of the normal overload dynamic balance is set = 4.99, and the normal overload dynamic limit value ΔN _n =0.005, the initial value of the design attack angle α α _init =40°, the speed roll angle is initially zero, and it is added after the flight speed decays enough.

如图3所示，为采用本发明所述方法进行仿真时，飞行器再入飞行的高度和速度演化图。其中，图3所示点1(峰值高度点)对应时刻表示飞行器在峰点高度的时刻，也是再入初始时刻；点2(峰值速度点)对应时刻为飞行器再入达到速度峰值的时刻；点3(动平衡结束点)对应时刻为动平衡结束时刻。As shown in FIG. 3 , it is an evolution diagram of the height and speed of the reentry flight of the aircraft when the method of the present invention is used for simulation. Among them, the corresponding time of point 1 (peak height point) shown in Figure 3 represents the moment when the aircraft is at the height of the peak point, which is also the initial moment of re-entry; the corresponding time of point 2 (peak speed point) is the time when the aircraft re-entries reaches the peak speed; 3 (end point of dynamic balance) corresponds to the end time of dynamic balance.

图3所示点2和点3之间的时间段即法向过载动态平衡段[t_init，t_end]。所述图3所示过载动平衡时间段内飞行器对应的设计攻角、速度倾侧角和法向过载的演化如图4所示。The time period between point 2 and point 3 shown in Fig. 3 is the normal overload dynamic balance period [t _init , t _end ]. The evolution of the design angle of attack, velocity roll angle and normal overload of the aircraft corresponding to the overload dynamic balance period shown in FIG. 3 is shown in FIG. 4 .

可见，在维持设计攻角初始值α_init一段时间后，法向过载N_n急剧增加(图4所示虚线1前)。在留有一定调整提前量Δt_α时，设计攻角开始调整，法向过载在预定区域[4.99±0.005]内达到动平衡(图4所示虚线1至虚线2之间)。当飞行速度得到足够衰减后，加入速度倾侧角(即为速度倾侧角不为零)，并继续调整设计攻角，使法向过载N_n在预定区域[4.99±0.005]内达到动态平衡(图4所示虚线2至虚线3之间)。由此可以看出，本发明实施例描述的攻角设计方法可以较理想实现亚轨道飞行器再入飞行的法向过载动平衡。It can be seen that after maintaining the initial value of the design angle of attack α _init for a period of time, the normal overload N _n increases sharply (before the dotted line 1 shown in Figure 4). When a certain adjustment advance amount Δt _α is left, the design angle of attack starts to be adjusted, and the normal overload reaches dynamic balance within the predetermined area [4.99±0.005] (between the dotted line 1 and the dotted line 2 shown in Figure 4). When the flight speed is sufficiently attenuated, add the speed roll angle (that is, the speed roll angle is not zero), and continue to adjust the design angle of attack, so that the normal overload N _n reaches a dynamic balance within the predetermined area [4.99±0.005] (Fig. 4 between dotted line 2 and dotted line 3). It can be seen from this that the method for designing the angle of attack described in the embodiment of the present invention can ideally realize the normal overload dynamic balance of the reentry flight of the suborbital vehicle.

如果将所述法向过载动平衡的期望中值N_{n_want}逐渐调低，经过多次仿真的结果分析，可将法向过载峰值压低至3.7～3.8左右。If the expected median value N _{n_want} of the normal overload dynamic balance is gradually lowered, the peak value of the normal overload can be reduced to about 3.7-3.8 after analyzing the results of multiple simulations.

对于本发明所述方法，对于不同的法向过载动平衡的期望中值N_{n_want}，其再入过程的轨迹特征如表1所示：For the method described in the present invention, for the expected median value N _{n_want} of different normal overload dynamic balances, the trajectory characteristics of its reentry process are shown in Table 1:

从表1中可以看到，随着法向过载动平衡的期望中值N_{n_want}的降低，其动压峰值和热流峰值将升高，说明维持较高的法向过载动平衡的期望中值N_{n_want}有利于降低动压峰值和热流峰值。还可以看出，法向过载动平衡的维持时间越长，其可实现的法向过载动平衡的期望中值N_{n_want}越低。It can be seen from Table 1 that with the decrease of the expected median value N _{n_want} of the normal overload dynamic balance, the peak value of dynamic pressure and heat flow will increase, indicating that the expected median value N of the normal overload dynamic balance will be maintained relatively high _{n_want} is good for reducing dynamic pressure peaks and heat flow peaks. It can also be seen that the longer the normal overload dynamic balance is maintained, the lower the expected median value N _{n_want} of the normal overload dynamic balance can be achieved.

同样对于此仿真算例，如采用现有攻角设计方法，即为采用式(1)设计攻角，其中设计攻角初始值α₀＝40°；设计攻角目标值α_end＝15°，设计攻角开始调整时飞行器速度的初始值V₁对应为仿真算例中的飞行器再入速度峰值，则设计攻角的下降斜率

即由不同的V₂唯一确定。Also for this simulation example, if the existing angle of attack design method is used, the angle of attack is designed using formula (1), where the initial value of the design angle of attack α ₀ =40°; the target value of the design angle of attack α _end =15°, The initial value V ₁ of the aircraft velocity when the design angle of attack starts to adjust corresponds to the peak re-entry velocity of the aircraft in the simulation example, then the descending slope of the design angle of attack is

That is, uniquely determined by different V ₂ .

对于现有方法，不同的攻角下降斜率

再入过程的轨迹特征如表2所示：For existing methods, different angle-of-attack descent slopes

The trajectory characteristics of the reentry process are shown in Table 2:

由对比表1和表2可知，采用本发明所述方法，可将最小法向过载动平衡的期望中值N_{n_want}压低至3.7；而如果采用现有攻角设计方法，其能够达到的最低法向过载峰值也在5.9以上。由此可见，本发明实施例所述的方法，可以大幅度的压低飞行器再入飞行过程中的法向过载峰值。By comparing Table 1 and Table 2, it can be known that adopting the method of the present invention can reduce the expected median value N _{n_want} of the minimum normal overload dynamic balance to 3.7; The peak overload is also above 5.9. It can be seen that the method described in the embodiment of the present invention can greatly reduce the peak value of the normal overload during the re-entry flight of the aircraft.

其次将说明本发明的攻角设计系数b₁、b₂、b₃、b₄获取方法的效果。Next, the effect of the method for obtaining the attack angle design coefficients b ₁ , b ₂ , b ₃ , and b ₄ of the present invention will be described.

图5为用获取的攻角设计预测值拟合攻角设计系数b₁、b₂、b₃、b₄的效果图，拟合的方法采用的是最小二乘法。可以从图中看出，对于不同的法向过载动平衡的期望中值N_{n_want}，拟和后的攻角设计值α_des与获得的再入攻角设计预测值

很好的匹配。Figure 5 shows the predicted value of the design with the obtained angle of attack The effect diagram of fitting the design coefficients b ₁ , b ₂ , b ₃ , b ₄ of the angle of attack, and the fitting method is the least square method. It can be seen from the figure that for different expected median values N _{n_want} of normal overload dynamic balance, the fitted design value of the angle of attack α _des and the obtained predicted value of the re-entry angle of attack

nice match.

最后将说明本发明的制导效果。Finally, the guidance effect of the present invention will be explained.

图6a至图6f为当实际再入飞行时的飞行器气动参数与所述再入飞行模型和同态预测模型中的飞行器气动参数相差±5％、±10％、±20％的情况下，在所述法向过载动平衡段内，采用本发明方法制导的实际再入飞行的法向过载与期望法向过载平衡中值的差值情况。Fig. 6a to Fig. 6f show that when the aircraft aerodynamic parameters during the actual re-entry flight differ from the aircraft aerodynamic parameters in the re-entry flight model and the homomorphic prediction model by ±5%, ±10%, ±20%, in the case In the normal overload dynamic balance section, the difference between the normal overload of the actual reentry flight guided by the method of the present invention and the expected normal overload balance median.

图6a至图6f中，“整体修正”所指线为本发明实施例一的攻角制导方法下，在所述法向过载动平衡段内的实际再入飞行的法向过载与期望过载平衡中值的差值情况。此时攻角制导对应为式(13)：In Figures 6a to 6f, the line indicated by "Overall Correction" is the normal overload and expected overload balance of the actual reentry flight in the normal overload dynamic balance section under the angle of attack guidance method of Embodiment 1 of the present invention The difference between the median values. At this time, the angle of attack guidance corresponds to formula (13):

${α α}_{cmd cmd} = = (({b b}_{11} + + {b b}_{22} \cdot &Center Dot; v v ((t t)) + + {b b}_{33} \cdot &Center Dot; {e e}^{{b b}_{44} \cdot \cdot h h ((t t))})) \times \times η η ((t t)) - - - - - - ((1313))$

图6a至图6f中，“b1针对修正+整体修正”所指线为本发明实施例二的攻角制导方法下，在所述法向过载动平衡段内的实际再入飞行的法向过载与期望过载平衡中值的差值情况。此时攻角制导对应为式(15)：In Fig. 6a to Fig. 6f, the line indicated by "b1 correction + overall correction" is the normal overload of the actual re-entry flight in the normal overload dynamic balance section under the angle-of-attack guidance method of Embodiment 2 of the present invention The difference from the median value of the desired overload balance. At this time, the angle of attack guidance corresponds to formula (15):

${α α}_{cmd cmd}^{' '} = = {b b}_{11}^{' '} + + (({b b}_{22} \cdot &Center Dot; v v ((t t)) + + {b b}_{33} \cdot \cdot {e e}^{{b b}_{44} \cdot \cdot h h ((t t))})) \times \times η η ((t t)) - - - - - - ((1515))$

从图6至图6f中可以看出，当不采用本发明的制导方法时，其法向过载平衡段内的实际法向过载与期望法向过载平衡中值存在误差，而采用本发明的制导方法，可以有效的降低飞行器再入飞行偏差带来的影响，使得飞行器实际再入飞行的法向过载与设计攻角下的法向过载趋于一致，达到制导目的。It can be seen from Fig. 6 to Fig. 6f that when the guidance method of the present invention is not used, there is an error between the actual normal overload and the expected normal overload balance in the normal overload balance section, while the guidance method of the present invention The method can effectively reduce the impact of the aircraft's re-entry flight deviation, so that the normal overload of the actual re-entry flight of the aircraft tends to be consistent with the normal overload at the design angle of attack, so as to achieve the purpose of guidance.

以上对本发明所提供的一种亚轨道飞行器再入飞行的攻角制导方法，进行了详细介绍，本文中应用了具体个例对本发明的原理及实施方式进行了阐述，以上实施例的说明只是用于帮助理解本发明的方法及其核心思想；同时，对于本领域的一般技术人员，依据本发明的思想，在具体实施方式及应用范围上均会有改变之处。综上所述，本说明书内容不应理解为对本发明的限制。Above, the angle-of-attack guidance method of a kind of suborbital vehicle reentry flight provided by the present invention has been introduced in detail. In this paper, specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only used To help understand the method and its core idea of the present invention; at the same time, for those skilled in the art, according to the idea of the present invention, there will be changes in the specific implementation and application scope. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. An attack angle guidance method for reentry flight of a sub-orbital vehicle is characterized by comprising the following steps:

step 1, before reentry flight of an aircraft, obtaining a design value of a reentry attack angle, wherein the design value of the reentry attack angle is represented as:

α_{des} = \{\begin{matrix} α_{0} \\ b_{1} + b_{2} \cdot v + b_{3} \cdot e^{b_{4} \cdot h} \\ α_{end} \end{matrix} \begin{matrix} v &GreaterEqual; V_{1} \\ V_{1} &GreaterEqual; V &GreaterEqual; V_{2} \\ V \leq V_{2} \end{matrix}

wherein alpha is_desIs the design value of reentrant angle of attack; alpha is alpha₀For designing angle of attackAn initial value; alpha is alpha_endDesigning a target value of an attack angle; v₁Starting to adjust the initial value of the speed of the aircraft for the designed attack angle; v₂Adjusted to alpha for design of angle of attack_endA time flight vehicle speed value; b₁、b₂、b₃、b₄Designing coefficients for an attack angle, wherein V is a flight speed value of the aircraft, and h is a flight height value of the aircraft;

step 2, calculating to obtain a design value alpha adopting the reentry attack angle by utilizing an aircraft reentry flight model and a homomorphic prediction model_desPredicted values of resistance and acceleration corresponding to each flying time when reentry flying is carried out

Step 3, in the process of the reentry flight of the aircraft, measuring in real time to obtain the drag acceleration D (t) of the aircraft at the current moment t, and combining the predicted value of the drag acceleration

Calculating to obtain a correction coefficient eta (t) of the design attack angle corresponding to the current moment t, specifically:

η (t) = \frac{{&Integral;}_{t_{0}}^{t} \hat{D} (t) dt}{{&Integral;}_{t_{0}}^{t} D (t) dt}

wherein, t₀Refers to the reentry flight starting time of the aircraft;

step 4, measuring in real time to obtain the current flight speed v (t) and the flight altitude h (t) of the aircraft, and correcting the design value of the reentry angle of attack obtained in the step 1 by using the correction coefficient eta (t) of the current design angle of attack to obtain an angle of attack guidance value alpha_cmd：

α_{cmd} = (b_{1} + b_{2} \cdot v (t) + b_{3} \cdot e^{b_{4} \cdot h (t)}) \times η (t);

The step 1 comprises the following steps:

step 11: obtaining the reentry attack angle design predicted value of each flight time under the normal overload dynamic balance condition of the aircraft by using the aircraft reentry flight model and the aircraft homomorphic prediction model

Step 12: acquiring the flight speed and the flight altitude corresponding to each flight moment of the aircraft through the simulation of the reentry of the aircraft into the flight model;

step 13: designing a predicted value according to a reentry attack angle of each flight time by using a least square method

And (3) combining the flying speed and the flying height with the following expression, and fitting to obtain an expression of an attack angle design value:

α_{des} = \{\begin{matrix} α_{0} \\ b_{1} + b_{2} \cdot v + b_{3} \cdot e^{b_{4} \cdot h} \\ α_{end} \end{matrix} \begin{matrix} v &GreaterEqual; V_{1} \\ V_{1} &GreaterEqual; V &GreaterEqual; V_{2} \\ V \leq V_{2} \end{matrix};

wherein the step 11 comprises:

establishing an aircraft reentry flight model and a homomorphic prediction model of the aircraft reentry flight, simulating the reentry flight state of the aircraft by using the reentry flight model, and calculating by using time as a variable in the reentry flight model; the initial state of the reentry flight model and the prediction model is the starting time t_initA corresponding aircraft state;

predicting the starting time t by utilizing the aircraft homomorphic prediction model_initStarting with a preset initial value alpha_initReentry flight is carried out for designing an attack angle alpha to achieve normal overload N_nGreater than or equal to a preset normal overload dynamic balance expected median value N_{n_want}At time t_{1_α}(ii) a Desired median value N of said normal overload dynamic balance_{n_want}Normal overload constraint values borne by aircraft loaders and equipment;

from i to 1, α₀＝α_initThe following steps are performed:

step 111: when the aircraft reenters the flight model and runs to t_{i_α}At the moment, the reentry flight time t of the aircraft is obtained from the reentry flight model_{i_α}Angle of attack alpha at a moment_i-1Predicting the aircraft t by using the aircraft homomorphic prediction model_{i_α}The flight state at the moment is the initial state of the homomorphic prediction model and is alpha_i-1-k′_{_α_i}(t-t_{i_α}) First normal overload peak of aircraft during reentry flight for design angle of attack alpha

Wherein, k'_{_α_i}＜k_{_α_i-1}When i is 1, k'_{_α_1}＝k_init，k_initAs an initial value of the angle of attack descent slope, k_init≥0；

Step 112: comparing the ith normal overload peak

And a desired normal overload dynamic equilibrium fluctuation region [ N ]_{n_want}±ΔN_n]And a falling slope k 'of the design angle of attack according to the comparison result'_{_α_i}Adjusting until the ith normal overload peak

A fluctuation region [ N ] in the expected normal overload dynamic balance_{n_want}±ΔN_n]And determining the corresponding design attack angle descending slope k at the moment_{_α_i}(ii) a The Δ N_nIs a preset normal overload fluctuation limit value delta N_nIs a desired median value N of the normal overload dynamic balance_{n_want}2% to 5%;

step 113: predicting t with an aircraft homomorphic prediction model_{i_α}The flight state of the aircraft at the moment is the initial state of the homomorphic prediction model and is alpha_i-1-k_{_α_i}(t-t_{i_α}) Normal overload N of aircraft during reentry flight for design angle of attack alpha_nPassing through the ith normal overload peakA wave zone [ N ] after and out of the desired normal overload dynamic balance_{n_want}±ΔN_n]At time t_{i+1_α}；

Step 114: set [ t ]_{i_α}，t_{i+1_α}]Within a time period, the design attack angle alpha is alpha_i-1-k_{_α_i}(t-t_{i_α})；

Step 115: when the falling slope k_{_α_i}K is less than or equal to the preset value₀When the normal overload dynamic balance of the aircraft is finished, the process is finished; otherwise, i is added by 1, and the step 111 is returned.

2. The method of claim 1, further comprising, after step 4:

step 5, according to the initial value alpha of the designed attack angle₀The design factor b1 of the attack angle is corrected so that the design factor b 'of the attack angle after correction'₁Satisfies the following conditions: when the reentry flight speed of the aircraft is V₁When the temperature of the water is higher than the set temperature,

wherein h is₁The reentry flight speed of the aircraft is V₁Flight height, t, corresponding to time₁The reentry flight speed of the aircraft is V₁The corresponding flying time;

specifically, the attack angle design coefficient b1 may be corrected by the following formula:

b_{1}^{'} = \{\begin{matrix} b_{1}^{start} \\ b_{1}^{start} + {&Integral;}_{t_{1}}^{t} \frac{b_{1} \times η (t) - b_{1}^{start}}{ΔT - (t - t_{1})} dt \\ b_{1} \times η (t) \end{matrix} \begin{matrix} t = t_{1} \\ t_{1} < t < t_{1} + ΔT \\ t &GreaterEqual; t_{1} + ΔT \end{matrix}

wherein,

b_{1}^{start} = α_{0} - (b_{2} \cdot v_{1} + b_{3} \cdot e^{b_{4} \cdot h_{1}}) \times η (t_{1});

Δ T is a preset adjustment time interval;

step 6, designing a coefficient b 'according to the corrected attack angle'₁Obtaining a corrected attack angle guidance value alpha'_cmd：

α_{cmd}^{'} = b_{1}^{'} + (b_{2} \cdot v (t) + b_{3} \cdot e^{b_{4} \cdot h (t)}) \times η (t) .

3. The method of claim 1, wherein when i is greater than or equal to 2, for t_{i+1_α}The updating specifically comprises:

at [ t ]_{i_α}，t_{i+1_α}]In the time period, the flight state of the aircraft in the reentry flight model is continuously used as the initial state of the homomorphic prediction model, and the prediction starts from the current moment and is carried out by alpha_i-1-k_{_α_i}(t-t_{i_α}) Normal overload N of aircraft during reentry flight for design angle of attack alpha_nPassing through the ith normal overload peak

A wave zone [ N ] after and out of the desired normal overload dynamic balance_{n_want}±ΔN_n]Time t'_{i+1_α}From t'_{i+1_α}As updated t_{i+1_α}。

4. The method of claim 1, wherein the adjustment timing advance is set to Δ t if and only if i is 1_αAt [ t ]_init，(t_{1_α}-Δt_α)]In the time period, the design attack angle alpha of the reentry flight of the aircraft is equal to the initial value alpha_init；

When the aircraft reenters the flight model and runs to t_{1_α}-Δt_αAt the moment, the aircraft t is predicted by utilizing the aircraft homomorphic prediction model_{1_α}-Δt_αThe flight state at the moment is the initial state of the homomorphic prediction model and is alpha₀-k′_{_α_1}(t-t_{1_α}+Δt_α) First normal overload peak of aircraft during reentry flight for design angle of attack alpha

Comparing the first normal overload peak

And a wave zone [ N ] of said desired normal overload dynamic balance_{n_want}±ΔN_n]The falling slope k of the design attack angle is determined according to the comparison result_{_α}Adjusting until the first normal overload peak

A fluctuation region [ N ] in the expected normal overload dynamic balance_{n_want}±ΔN_n]And determining the corresponding design attack angle descending slope k at the moment_{_α_1}；

Predicting t with an aircraft homomorphic prediction model_{1_α}-Δt_αThe flight state of the aircraft at the moment is the initial state of the homomorphic prediction model and is alpha_init-k_{_α_1}(t-t_{1_α}+Δt_α) Normal overload N of aircraft during reentry flight for design angle of attack alpha_nPassing said first normal overload peak

A wave zone [ N ] after and out of the desired normal overload dynamic balance_{n_want}±ΔN_n]At time t_{2_α}；

Set [ t ]_{1_α}-Δt_α，t_{2_α}]Time periodInner and outer design attack angles alpha_init-k_{_α_1}(t-t_{1_α}+Δt_α)。

5. The method of claim 4, wherein when i is 1, t is selected_{1_α}The updating specifically comprises:

at t_init≤t≤(t_{1_α}-Δt_α) Continuously taking the current flight state of the aircraft in the reentry flight model as the initial state of the homomorphic prediction model, and predicting from the current moment to the initial value alpha_initReentry flight is carried out for designing an attack angle alpha to achieve normal overload N_nGreater than or equal to the desired median value N of the normal overload dynamic balance_{n_want}Time t'_{1_α}From t'_{1_α}As updated t_{1_α}。

6. The method of claim 1, wherein said decreasing slope k 'of design angle of attack according to comparison results in step 112'_{_α_i}The adjustment is carried out, and specifically:

if it is

N_{n_\max}^{i_α} > N_{n_want} + Δ N_{n},

Decreasing slope k 'for increasing design angle of attack'_{_α_i}；

If it is

N_{n_\max}^{i_α} < N_{n_want} - Δ N_{n},

Down slope k 'to reduce design angle of attack'_{_α_i}。

7. The method of claim 6, wherein the droop slope k 'of design angle of attack is increased or decreased'_{_α_}The i is specifically as follows:

down slope k 'to the design angle of attack'_{_α_i}By increasing or decreasing a preset adjustment quantity delta_{k_α}。