阅读说明：本技术 一种基于轴向过载的两级飞行器分离时刻判别方法 (Two-stage aircraft separation time discrimination method based on axial overload ) 是由 奚勇 沈洁 陈光山 夏斌 冯昊 廖幻年 朱雯雯 刘露 于 2020-05-13 设计创作，主要内容包括：本发明公开了一种基于轴向过载的两级飞行器分离时刻判别方法,包括以下步骤：步骤一：确定轴向过载作为在线实时判别分离的基础变量；步骤二：计算分离前后飞行器轴向过载数值；步骤三：根据步骤二中所得,确定安全分离时轴向过载安全阈值；步骤四：对实时过载信号进行均值滤波处理；步骤五：确定安全分离时刻轴向过载和安全分离阈值之间的大小关系；步骤六：记录步骤五中满足安全分离条件的时间点,作为主级启控时刻。本发明根据飞行器两级分离前后轴向过载出现明显变化的特点,据此实现对两级分离时刻进行在线实时判别。(The invention discloses a two-stage aircraft separation time judging method based on axial overload, which comprises the following steps of: the method comprises the following steps: determining axial overload as a basic variable for online real-time discrimination and separation; step two: calculating axial overload values of the aircrafts before and after separation; step three: determining an axial overload safety threshold value during safety separation according to the result obtained in the step two; step four: carrying out mean value filtering processing on the real-time overload signal; step five: determining the magnitude relation between the axial overload and the safe separation threshold value at the safe separation moment; step six: and recording the time point meeting the safe separation condition in the step five as the primary control starting time. According to the characteristic that the axial overload of the aircraft is obviously changed before and after two-stage separation, online real-time judgment on the two-stage separation moment is realized.)

1. A two-stage aircraft separation time judging method based on axial overload is characterized by comprising the following steps:

the method comprises the following steps: determining axial overload as a basic variable for online real-time discrimination and separation;

step two: calculating axial overload values of the aircrafts before and after separation;

step three: determining an axial overload safety threshold value during safety separation according to the result obtained in the step two;

step four: carrying out mean value filtering processing on the real-time overload signal;

step five: determining the magnitude relation between the axial overload and the safe separation threshold value at the safe separation moment;

step six: and recording the time point meeting the safe separation condition in the step five as the primary control starting time.

2. The two-stage aircraft separation moment discrimination method based on axial overload according to claim 1, characterized in that the first step is: the change rule of the pneumatic characteristic at the moment of separation of the boosting stage is analyzed, the parameters such as the mass of the aircraft, the axial force coefficient and the like before and after separation are changed, the analysis result is consistent, the axial overload signals of the aircraft before and after separation can directly reflect the safe separation of the front stage and the rear stage, the axial overload is selected as the safe separation judgment basis, the physical significance is clear, and the engineering application is easier to realize.

3. The two-stage aircraft separation moment discrimination method based on axial overload according to claim 1, characterized in that the second step: selecting a typical boosting stage separation state of the aircraft, respectively calculating the corresponding axial overload sizes of the aircraft before and after boosting stage separation, and confirming the size relationship.

4. A two-stage aircraft separation moment discrimination method based on axial overload according to claim 3, characterized in that the third step: the setting of the safety threshold mainly depends on the two theoretical values calculated in the second step, and the value of the value must be within the range determined by the two theoretical values.

5. The two-stage aircraft separation moment discrimination method based on axial overload according to claim 4, characterized in that the fourth step: and rapidly processing the signal by adopting a method of sampling and averaging for multiple times, and comparing the processed axial overload with a safety threshold.

6. The two-stage aircraft separation moment discrimination method based on axial overload according to claim 5, characterized in that the fifth step: according to the safety threshold set in the third step, the real-time axial overload in the fourth step is compared with the safety threshold on line; when the real-time axial overload is smaller than a safety threshold value, the safe separation between the boosting stage and the main stage is indicated; otherwise, the separation is incomplete.

Technical Field

The invention relates to the field of flight control of unmanned aerial vehicles, in particular to an online real-time discrimination method for two-stage safety separation of an aircraft.

Background

The current research of unmanned aerial vehicles tends to the development of high speed and long range gradually, while the improvement of flight speed and range usually adopts a multi-stage boosting scheme, the boosting stage accelerates the aerial vehicle to a certain flight speed, and then the air is thrown away by an interstage separation mechanism. The difference of the aerodynamic characteristics of the aircrafts before and after interstage separation is large, the attitude instability of the aircrafts is easily caused by the interaction force and the aerodynamic interference between the booster stage and the main stage, and the requirement of a flight control system on accurate judgment of the separation time of the front stage and the rear stage is high. The primary stage starting and controlling time is directly related to success or failure of the whole flight test, and if the primary stage is started and controlled in advance, the danger of collision between the front stage and the rear stage is easily caused; and if the primary level lags the control starting, the primary level has flight risk of the uncontrolled section.

Therefore, the accurate judgment of the interstage safe separation moment is used as a key link for the interstage separation stable control, and the online real-time judgment is necessary through corresponding measures, so that the timely starting and control of the main stage after separation are ensured, and the interstage separation control quality of the aircraft is improved.

Disclosure of Invention

In order to solve a series of problems brought by judging the interstage separation time of the aircraft, the flight state quantity with strong correlation before and after two-stage separation, namely axial overload is searched as a basic parameter for judging the separation time, so that the influence caused by inaccurate starting and controlling opportunity of a main stage after separation is avoided to a certain extent, and a two-stage aircraft separation time judging method based on axial overload is provided to realize stable control of interstage separation.

In order to achieve the purpose, the invention is realized by the following technical scheme:

a two-stage aircraft separation time judging method based on axial overload comprises the following steps:

the method comprises the following steps: determining axial overload as a basic variable for online real-time discrimination and separation;

step two: calculating axial overload values of the aircrafts before and after separation;

step three: determining an axial overload safety threshold value during safety separation according to the result obtained in the step two;

step four: carrying out mean value filtering processing on the real-time overload signal;

step five: determining the magnitude relation between the axial overload and the safe separation threshold value at the safe separation moment;

step six: and recording the time point meeting the safe separation condition in the step five as the primary control starting time.

Further, the first step: analyzing the change rule of the aerodynamic characteristics at the moment of separation of the booster stage, and changing parameters such as the mass of the aircraft, the axial force coefficient and the like before and after separation, wherein for example, the mass has larger change but is not easy to be directly measured; the analysis results are consistent, the axial overload signals of the aircrafts before and after separation can directly reflect the front-stage and rear-stage safety separation, the axial overload is selected as a safety separation judgment basis, the physical significance is clear, and the engineering application is easier to realize.

Further, the second step: selecting a typical boosting stage separation state of the aircraft, respectively calculating the corresponding axial overload sizes of the aircraft before and after boosting stage separation, and confirming the size relationship.

Further, the third step: the setting of the safety threshold mainly depends on the two theoretical values calculated in the second step, and the value of the value must be within the range determined by the two theoretical values.

Further, the fourth step: filtering the overload signal output by the inertial measurement combination measuring device in real time, avoiding separation misjudgment caused by burrs and outliers in the overload signal, rapidly processing the signal by adopting a method of sampling and averaging for multiple times in general engineering, and comparing the processed axial overload with a safety threshold.

Further, the fifth step: and according to the safety threshold set in the third step, comparing the real-time axial overload in the fourth step with the size of the safety threshold on line. When the real-time axial overload is smaller than a safety threshold value, the safe separation between the boosting stage and the main stage is indicated; otherwise, the separation is incomplete.

Step six: and recording the time point meeting the safe separation condition in the step five as the primary control starting time.

The advantages of the invention include: the aerodynamic characteristic change rule of the aircraft in a typical separation state is analyzed, the axial overload of the aircraft is used as a basic parameter for judging the two-stage separation time, and the physical concept is clear; setting a safety threshold value at the time of safety separation through calculation and analysis, sampling for multiple times to carry out mean value filtering processing on real-time axial overload, preventing separation misjudgment, comparing a processing result with the safety threshold value in real time, and determining a safety separation time point as a main-level starting and controlling time; from the aspect of engineering application, on the basis of not increasing any hardware cost, the method solves the online judgment of the separation time of the two-stage aircraft, avoids early or late start control of the main stage after boosting separation, reduces the risk of separation control, improves the flight control quality of the aircraft, and ensures the separation safety.

Drawings

Fig. 1 is a flow chart of an implementation of a two-stage aircraft separation time determination method based on axial overload provided by the invention.

Detailed Description

The invention is further illustrated below with reference to the figures and examples.

Obtaining the flight state of the aircraft at two-stage separation moment, and calculating the theoretical value N of axial overload before and after separation_x1、N_x2(ii) a With axial overload N before separation_x1For example, the calculation formula is shown in the following formula (1);

wherein: q. q.s₁Dynamic pressure of real-time flight of the aircraft at the moment of separation; k is a radical of₁Is about Ca₁,S₁,Mass₁Correlation f function，Ca₁,S₁,Mass₁The axial force coefficient, the cross sectional area and the mass of the aircraft are respectively;

N_x2is calculated by the method and N_x1The calculation methods are the same, and are not described herein again.

Calculating the theoretical values of axial overload before and after separation according to the formula (1), and determining the size relationship between the two theoretical values, wherein the expression of the mathematical relationship is shown as the formula (2);

N_x2＜N_x1(2)

defining the value range of the separation safety threshold according to the formula (2), and carrying out N_{x_safe}The value of (2) is restricted, and the restriction condition is shown as a formula (3);

N_x2＜N_{x_safe}＜N_x1(3)

according to the formula (3), a safe separation threshold value N is set within a range defined by the constraint condition_{x_safe}

N_{x_safe}＝N_x2+(N_x1-N_x2)×a (4)

Wherein the value range of the proportionality coefficient a is within 0-1.

In a severe vibration environment of an aircraft, an overload signal output by an inertia measuring device contains high-frequency components, so that an overload output value fluctuates around a steady-state value of the overload output value, erroneous judgment of separation time is easily caused, real-time axial overload needs to be sampled for multiple times on line and averaged, a calculation formula is as shown in the following formula (5), and axial overload N after processing is obtained_x；

Wherein n is generally 10,15,20 …

Will N_xWith a set safety threshold value N_{x_safe}And comparing, and when the two satisfy the following constraint conditions, indicating that the front and the back are safely separated.

N_x＜N_{x_safe}(6)

And recording a time point t corresponding to the satisfaction formula (6) as the separated main-level start control moment.

Although the present invention has been described with reference to the preferred embodiments, it is not intended to limit the present invention, and those skilled in the art can make variations and modifications of the present invention without departing from the spirit and scope of the present invention by using the methods and technical contents disclosed above.