CN106372307A - Civil aircraft air flow angle estimation method based on pneumatic model - Google Patents

Abstract

The invention belongs to flight control technologies, and provides a civil aircraft air flow angle estimation method based on a pneumatic model. The method comprises the step 1 of calculating out a total lift coefficient CL and a total side force coefficient CY of an aircraft; the step 2 of utilizing an aerodynamic force wind tunnel experiment to obtain an interpolation table of aerodynamic coefficients generated by all components; the step 3 of classifying aerodynamic force generated by all the components; the step 4 of obtaining a variable polynomial of degree N of an attack angle, and obtaining a variable polynomial of degree M of a sideslip angle; the step 5 of overlaying a plurality of parameters of the variable polynomial of degree N of the attack angle to obtain a total variable polynomial of degree N of the attack angle, and overlaying a plurality of parameters of the variable polynomial of degree M of the sideslip angle to obtain a total variable polynomial of degree M of the sideslip angle; the step 6 of reversely solving the attack angle through the variable polynomial of degree N, and reversely solving the sideslip angle through the variable polynomial of degree M; the step 7 of determining a real-time attack angle and a real-time sideslip angle according to actual value ranges of the attack angle and the side slip angle.

Description

A kind of civil aircraft flow angle method of estimation based on aerodynamic model

Technical field

The invention belongs to flight control technology, it is related to a kind of flow angle method of estimation being applied to civil aircraft.

Background technology

The angle of attack of aircraft and yaw angle are particularly significant for flight mechanics, and its certainty of measurement is directly connected to the flight of aircraft Safety and flight quality.The lift of aircraft and resistance are closely related with the angle of attack, will lead to aircraft when the angle of attack exceedes the critical angle of attack Stall, it is out of hand to be embodied in aircraft, automatically into rolling or Dutch roll state, highly drastically reduces, in turn results in aircraft Accident；In the horizontal Heading control of aircraft flight control system, sideslip angle signal serves the effect increasing steady and coordinate turn, and And the deviation of yaw angle also will lead to aircraft to produce extra energy loss.With the requirement more and more higher to control law for the main frame, The angle of attack and sideslip angle signal with degree of precision need to be introduced in design of control law.

The approach of the existing acquisition angle of attack and yaw angle mainly has three kinds: measuring method, integration method, method of geometry relation.

Measuring method: traditional angle of attack and yaw angle typically pass through weathercock sensor on aircraft, pressure difference sensor and Zero-pressure differential sensor etc. is measuring, but the office that this kind of sensor is due to being frozen, high frequency fitful wind is relevant with state of flight Portion's circulation and the impact of installation site and rotational angular velocity, almost invariably can cause very big zero deviation.Therefore The angle of attack measured and yaw angle signal accuracy relatively low it is impossible to be directly used as the feedback signal of control system.

Integration method: the overload being measured using Inertial Measurement Unit (imu) and angular speed are to six-degree-of-freedom dynamics equation Carry out numerical integration, try to achieve the speed of return capsule, the angle of attack, yaw angle etc..But the error of accelerometer and angular rate gyroscope, attitude Initial value error, discreteness of data acquisition etc., all may lead to the cumulative error integrating, especially because acceleration of gravity is with height Degree declines and increases, and significantly exacerbates the speed that integration dissipates.

Method of geometry relation: the attitude being provided using gnc and velocity information, according to the angle of attack and yaw angle and speed and attitude angle Between geometrical relationship, calculate the angle of attack and yaw angle.The difficult point of the method is measurement or the estimation of wind speed.

Measuring method, integration method and method of geometry relation are affected larger, at this stage to this in itself by extraneous factor or device The processing method of a little impacts is not also too perfect, and precision is relatively low.

Content of the invention

Goal of the invention: a kind of civil aircraft flow angle method of estimation based on aerodynamic model is provided, the accurate angle of attack can be obtained With yaw angle signal value.

A kind of technical scheme: civil aircraft flow angle method of estimation based on aerodynamic model, comprising:

Step 1: by current total life l of the aircraft of acquisition, total side force y, quality m, longitudinal acceleration a_by, lateral acceleration Degree a_bz, dynamic pressure q, wing area of reference s_w, calculate aircraft total life coefficient c_lWith total lateral force coefficient c_y, formula is as follows:

$\left\{\begin{array}{c}l=c_{l}q{s}_w=m{a}_{by}\\ y=c_y{\mathrm{qs}}_w={\mathrm{ma}}_{bz}\end{array}\right.\&doublerightarrow;\left\{\begin{array}{c}{c}_l=m{a}_{by}/q{s}_w\\ c_y={\mathrm{ma}}_{bz}/{\mathrm{qs}}_w\end{array}\right.;$

Step 2: obtain the interpolation table of the aerodynamic coefficient that each part produces using aerodynamic force wind tunnel test；

Step 3: the aerodynamic force that each part is produced is classified respectively；The lift that each part produces can be divided into and angle of attack phase Close and two classes unrelated with the angle of attack；The side force that each part produces can be divided into two related and unrelated with yaw angle to yaw angle Class；

Step 4: the aerodynamic coefficient related to the angle of attack is carried out curve fitting from interpolation table, obtains the unitary with regard to the angle of attack Polynomial of degree n；The aerodynamic coefficient related to yaw angle is carried out curve fitting from interpolation table, obtains the unitary with regard to yaw angle M order polynomial；

Step 5: by obtain several with regard to the angle of attack Unitary Polynomial of n Degree enter line parameter superposition obtain total with regard to meeting The Unitary Polynomial of n Degree at angle；By obtain several with regard to yaw angle unitary m order polynomial enter line parameter superposition obtain total Unitary m order polynomial with regard to yaw angle；

Step 6: the angle of attack is gone out by Unitary Polynomial of n Degree reverse；Yaw angle is gone out by unitary m order polynomial reverse；

Step 7: the real-time angle of attack and yaw angle be can determine that according to the actual span of the angle of attack and yaw angle.

Beneficial effect: awing the angle of attack is maintained in less numerical range so that its aerodynamic force due to civil aircraft Wind tunnel test result more accurate.It is applied to the flow angle method of estimation based on aerodynamic model of civil aircraft, its effect is Using the overload measurement data reduction aerodynamic coefficient of civil aircraft, using the more accurate aerodynamic force wind tunnel test of civil aircraft The result reverse angle of attack and yaw angle, thus obtain the more accurate angle of attack and yaw angle signal value.The advantage of the method is only Affected by wind-tunnel test accuracy, calculating is simple, be easy to Project Realization, need not increase additional devices, and estimated accuracy is higher, Under technical conditions, the precision of wind tunnel test is better than the impact that extraneous factor or device resolve to flow angle at this stage.

Brief description

Fig. 1 be the air-flow angular estimation based on aerodynamic model realize schematic diagram.

Specific embodiment

The invention will be further described below in conjunction with the accompanying drawings.

A kind of civil aircraft flow angle method of estimation based on aerodynamic model, as shown in Figure 1, comprising:

Step 1: by current total life l of the aircraft of acquisition, total side force y, quality m, longitudinal acceleration a_by, lateral acceleration Degree a_bz, dynamic pressure q, wing area of reference s_w, calculate aircraft total life coefficient c_lWith total lateral force coefficient c_y, formula is as follows:

$\left\{\begin{array}{c}l=c_{l}q{s}_w=m{a}_{by}\\ y=c_y{\mathrm{qs}}_w={\mathrm{ma}}_{bz}\end{array}\right.\&doublerightarrow;\left\{\begin{array}{c}{c}_l=m{a}_{by}/q{s}_w\\ c_y={\mathrm{ma}}_{bz}/{\mathrm{qs}}_w\end{array}\right.;$

Step 2: obtain the interpolation table of the aerodynamic coefficient that each part produces using aerodynamic force wind tunnel test.

The lift of aircraft can regard fuselage, wing, elevator, horizontal tail, spoiler, wing flap, undercarriage, electromotor etc. as The lift sum that each part produces, along with the lift caused by the factors such as aeroelasticity, ground effect；The side force of aircraft is permissible Regard the side force sum of each part such as empennage, spoiler, rudder generation as, along with the side caused by the factors such as aeroelasticity Power.

Step 3: the aerodynamic force that each part is produced is classified respectively；The lift that each part produces can be divided into and angle of attack phase Close and two classes unrelated with the angle of attack；The side force that each part produces can be divided into two related and unrelated with yaw angle to yaw angle Class.

Step 4: the aerodynamic coefficient related to the angle of attack is carried out curve fitting from interpolation table, obtains the unitary with regard to the angle of attack Polynomial of degree n；The aerodynamic coefficient related to yaw angle is carried out curve fitting from interpolation table, obtains the unitary with regard to yaw angle M order polynomial.

For the part related to the angle of attack, such as rigid body aircraft basic lift coefficient cl_basic is a two-dimensional interpolation Table, its size is determined by the angle of attack, 2 factors of Mach number, can extract current Mach number corresponding according to real-time Mach number Dimension interpolation table, and then one-dimensional interpolation table is carried out curve fitting according to the angle of attack, obtain a Unitary Polynomial of n Degree with regard to the angle of attack (n is bigger, and matching is more accurate).In the same manner, for the part related to yaw angle, the lateral force coefficient cy_ that for example rudder kick produces Rud is a three-dimensional interpolation table, and its size is determined by yaw angle, Mach number and 3 factors of rudder, can be first according in real time Mach number extract current Mach number corresponding two-dimensional interpolation table, extract further according to real-time rudder and work as front direction The corresponding one-dimensional interpolation table of angle of rudder reflection, and then one-dimensional interpolation table is carried out curve fitting according to yaw angle, obtain one with regard to side The unitary m order polynomial (m is bigger, and matching is more accurate) at sliding angle.

Step 5: by obtain several with regard to the angle of attack Unitary Polynomial of n Degree enter line parameter superposition obtain total with regard to meeting The Unitary Polynomial of n Degree at angle；By obtain several with regard to yaw angle unitary m order polynomial enter line parameter superposition obtain total Unitary m order polynomial with regard to yaw angle.

The lift coefficient of each part related to the angle of attack all can get a Unitary Polynomial of n Degree with regard to the angle of attack, by this A series of Unitary Polynomial of n Degree enters line parameter superposition, and then obtains a total Unitary Polynomial of n Degree with regard to the angle of attack；With The lateral force coefficient of the related each part of yaw angle all can get a unitary m order polynomial with regard to yaw angle, and this is a series of Unitary m order polynomial enter line parameter superposition, and then obtain a total unitary m order polynomial with regard to yaw angle.

Step 6: the angle of attack is gone out by Unitary Polynomial of n Degree reverse；Yaw angle is gone out by unitary m order polynomial reverse.

The lift coefficient of each part related to the angle of attack can be by aircraft total life coefficient c_lDeduct each portion unrelated with the angle of attack The lift coefficient of part obtains, then reverse can go out n angle of attack value by total Unitary Polynomial of n Degree with regard to the angle of attack；With sideslip The lateral force coefficient of the related each part in angle can be by aircraft total lateral force coefficient c_yDeduct the side force system of each part unrelated with yaw angle Number obtains, then reverse can go out m sideslip angle value by total unitary m order polynomial with regard to yaw angle.

Step 7: the real-time angle of attack and yaw angle be can determine that according to the actual span of the angle of attack and yaw angle.

Claims (1)

1. a kind of civil aircraft flow angle method of estimation based on aerodynamic model is it is characterised in that include:

Step 1: by current total life l of the aircraft of acquisition, total side force y, quality m, longitudinal acceleration a_by, lateral acceleration a_bz, dynamic pressure q, wing area of reference s_w, calculate aircraft total life coefficient c_lWith total lateral force coefficient c_y, formula is as follows:

$\left\{\begin{array}{c}l=c_{l}q{s}_w=m{a}_{by}\\ y=c_y{\mathrm{qs}}_w={\mathrm{ma}}_{bz}\end{array}\right.\&doublerightarrow;\left\{\begin{array}{c}{c}_l=m{a}_{by}/q{s}_w\\ c_y={\mathrm{ma}}_{bz}/{\mathrm{qs}}_w\end{array}\right.;$

Step 2: obtain the interpolation table of the aerodynamic coefficient that each part produces using aerodynamic force wind tunnel test；

Step 3: the aerodynamic force that each part is produced is classified respectively；The lift that each part produces can be divided into related to the angle of attack And two classes unrelated with the angle of attack；The side force that each part produces can be divided into two classes related and unrelated with yaw angle to yaw angle；

Step 4: the aerodynamic coefficient related to the angle of attack is carried out curve fitting from interpolation table, obtains unitary n time with regard to the angle of attack Multinomial；The aerodynamic coefficient related to yaw angle is carried out curve fitting from interpolation table, obtains unitary m time with regard to yaw angle Multinomial；

Step 5: by obtain several with regard to the angle of attack Unitary Polynomial of n Degree enter line parameter superposition obtain total with regard to the angle of attack Unitary Polynomial of n Degree；By obtain several with regard to yaw angle unitary m order polynomial enter line parameter superposition obtain total with regard to The unitary m order polynomial of yaw angle；

Step 6: the angle of attack is gone out by Unitary Polynomial of n Degree reverse；Yaw angle is gone out by unitary m order polynomial reverse；

Step 7: the real-time angle of attack and yaw angle be can determine that according to the actual span of the angle of attack and yaw angle.