CN103852081B - Vacuum speed resolving method for air data/serial inertial navigation combined navigation system - Google Patents

Abstract

The invention discloses a vacuum speed resolving method for an air data/serial inertial navigation combined navigation system. The method comprises the following steps: calculating a scale factor between the vacuum speed and ground velocity according to a vector relation among the vacuum speed, ground velocity and wind speed based on the characteristic that upper atmosphere is mainly in horizontal flow by utilizing an attack, a sideslip angle and posture of a carrier, and resolving the vacuum speed through numerical calculation. According to the method, the defect that the vacuum speed is severely lagged due to the temperature measurement time constant in a conventional vacuum speed calculation method depending on atmospheric temperature parameters is overcome, and influence of the vacuum speed which is severely influenced by the atmospheric temperature parameters and dependence of uncertain external information of the vacuum speed estimation method on aircraft dynamics parameters are avoided, so that the measuring lag of the vacuum speed and influence on environmental factors are solved.

Description

True air speed calculation method for atmosphere data/inertial navigation integrated navigation system

Technical field:

The present invention relates to a kind of true air speed calculation method, more particularly, to a kind of combination for atmosphere data/inertial navigation are led The true air speed calculation method of boat system.

Background technology:

Air data system (air data system, abbreviation ads) is to complete atmospheric parameter perception, measurement, resolve and defeated The important airborne Aerial Electronic Equipment going out, using the Atmospheric Characteristics ginseng around sensor (Pressure/Temperature/angular transducer) survey aircraft Number, be then passed through air data computer carry out related resolve and correct, complete stagnation pressure from origin stream, static pressure, dynamic pressure, quiet Temperature, the angle of attack, yaw angle, highly, the measurement of the atmosphere data such as lifting speed, indicator air speed, true air speed, Mach number.Strap down inertial navigation is led Boat (strapdown inertial navigation system, abbreviation sins) is to obtain carrier according to Newton mechanics law to lead A kind of self-aid navigation method of boat information, it utilizes the inertance element sensitive carrier movable information such as gyroscope, accelerometer, so Afterwards computing is integrated by computer and obtains the navigational parameters such as attitude, speed and the position of carrier.

Both navigation mode respectively has feature: sins abundant information, and navigation accuracy is higher, but short transverse is unstable；ads There is not cumulative error in elevation carrection, the angle of attack, sideslip angular measurement real-time are excellent, but pressure measurement pipeline lag characteristic, temperature lag etc. Factor causes the hysteresis characteristic of true air speed measurement.Therefore sins and ads has very strong complementarity, and ads is highly carried out to sins Damping has reached the commonly used degree of engineering, and uses sins information to improve true air speed measurement performance, be based on sins/ads Measuring wind speed be then sins/ads combined system research emphasis.

True air speed calculation method currently used for atmosphere data/inertial navigation integrated navigation system is less, and true air speed resolves Method can be largely classified into two classes, and a class is aircraft dynamics equation and fly control parameter and be combined to be estimated, its thought is will be true Air speed as a quantity of state, sets up state equation according to flight dynamics model, according to Aerial Electronic Equipment metrical information and its with The relation of quantity of state sets up measurement equation, realizes true air speed using Kalman filtering and resolves, conventional has common Kalman filtering Algorithm (kf algorithm), expanded Kalman filtration algorithm (ekf algorithm) and uncented Kalman filter algorithm (ukf algorithm)；Another kind of Be by external information increase quantity of information carry out true air speed estimation, conventional is to increase gps equipment, using gps provide ground velocity, Flight path angle information, the vector correlation according to true air speed, ground velocity and wind speed carries out true air speed solution.

Carry out true air speed estimation in conjunction with aircraft dynamics equation with flying control parameter, need to obtain comprehensive aircraft dynamics ginseng Number and flight control parameter, are difficult to meet this demand in engineer applied, resolve principle complicated.Simulation result shows, the method True air speed resolution error can control within 2m/s, effect preferably (see m.l.fravolini, m.pastorelli etc., 《model-based approaches for the airspeed estimation and fault monitoring of an unamaned aerial vehicle》).Quantity of information is increased by external information and carries out true air speed estimation, principle simply may be used Lean on, applied widely, but still need to using differential pressure measurement information it is impossible to avoid the delayed problem of true air speed, only can be to differential pressure It is modified with the scale factor of true air speed, meanwhile, due to introducing external information, lead to autonomy to decline, Yi Shougan Disturb, credibility not high (see amcho, jihoon kim etc., " wind estimation and airspeed calibration using a uav with a single-antenna gps receiver and pitot tube》).

Content of the invention:

The technical problem to be solved is to overcome the existing true air speed calculating side depending on atmospheric temperature parameter Method causes greatly the defect of the delayed wretched insufficiency of true air speed because of temperature measurement time constant, it is to avoid true air speed is seriously joined by atmospheric environment The impact of the number and true air speed evaluation method dependency to the uncertainty external information such as aircraft dynamics parameter, provides one kind It is not subject to the measurement delay of true air speed and the true air speed calculation method of such environmental effects, the method is applied to atmosphere data/strapdown Inertial navigation system, based on feature based on bottom horizontal flow sheet for the upper atmosphere, closes according to the vector between true air speed, ground velocity and wind speed System, using the scale factor between the Attitude Calculation true air speed of the angle of attack, yaw angle and carrier and ground velocity, by numerical computations to true Air speed is solved, it is to avoid interference to true air speed for the environmental factorss, solves true air speed measurement delay impact wind speed and resolves, flies The problem of row control performance.

The present invention adopts the following technical scheme that a kind of true air speed for atmosphere data/inertial navigation integrated navigation system Calculation method, methods described is related to air data system, strapdown inertial navigation system, comprises the following steps:

Step 1, speed position information read: be loaded into the longitude that the inertial navigation system being affected by air data system exports Long, latitude lati, height heig, east orientation speed v_e, north orientation speed v_n, sky orientation speed v_u, longitude, latitude unit are degree, highly Unit is rice, and speed unit is m/s；

Step 2, transformation matrix solve: be loaded into the roll angle γ of inertial navigation system output₀, pitching angle theta₀, course angle ψ₀, Unit is degree, determines that carrier coordinate system is transformed into the transformation matrix of geographic coordinate system according to Euler's horn cupping, specifically includes:

Step 201, the attitude angular unit that inertial navigation system exports is converted to by degree by radian according to following formula,

γ=γ₀* π/180, θ=θ₀* π/180, ψ=ψ₀* π/180,

In formula, γ, θ, ψ are respectively the roll angle that Conversion of measurement unit is radian, the angle of pitch, course angle information；

Step 202, it is transformed into the transformation matrix of carrier coordinate system according to following formula computed geographical coordinates

$c_n^b=\left[\begin{array}{ccc}\cos \mathrm{\γ}\cos \mathrm{\ψ}+\sin \mathrm{\γ}\sin \mathrm{\θ}\sin \mathrm{\ψ}& -\cos \mathrm{\γ}\sin \mathrm{\ψ}+\sin \mathrm{\γ}\sin \mathrm{\θ}\cos \mathrm{\ψ}& -\sin \mathrm{\γ}\cos \mathrm{\θ}\\ \cos \mathrm{\θ}\sin \mathrm{\ψ}& \cos \mathrm{\θ}\cos \mathrm{\ψ}& \sin \mathrm{\θ}\\ \sin \mathrm{\γ}\cos \mathrm{\ψ}-\cos \mathrm{\γ}\sin \mathrm{\θ}\sin \mathrm{\ψ}& -\sin \mathrm{\γ}\cos \mathrm{\ψ}-\cos \mathrm{\γ}\sin \mathrm{\θ}\cos \mathrm{\ψ}& \cos \mathrm{\γ}\cos \mathrm{\θ}\end{array}\right];$

Step 3, design conditions judge: according to sky orientation speed v_uJudged, if | v_u| ＜ 2m/s, return to step 1, if | v_u | >=2m/s, then carry out subsequent step；

Step 4, effective acceleration are extracted: extract acceleration measuring value, extract carrier acceleration, concrete steps include:

Step 401, the unit of latitude is converted to radian lati=lati* π/180 by degree；

Step 402, according to carrier positions, earth radius and earth ellipticity, calculate radius of curvature of the earth,

r_m=r_e(1-2f+3fsin²(lati)), r_n=r_e(1+fsin²(lati))

In formula, r_e, f be respectively earth radius, earth ellipticity, r_m、r_nRadius of curvature of the earth needed for inertial reference calculation；

Step 403, according to transformation matrixAccelerometer output is transformed under navigation system,In formula, f_b、 f_nIt is respectively body system, the specific force navigating under system；

Step 404, the harmful acceleration removing in specific force, extract carrier acceleration, resolve for speed, position,

${\mathrm{\ω}}_{enn}=\left[\begin{array}{c}-\frac{v_n}{(r_m+heig)}\\ \frac{v_e}{(r_n+heig)}\\ \frac{v_e\tan \left(lati\right)}{(r_n+heig)}\end{array}\right],{\mathrm{\ω}}_{ien}=\left[\begin{array}{c}0\\ {\mathrm{\ω}}_{ie}\cos \left(lati\right)\\ {\mathrm{\ω}}_{ie}\sin \left(lati\right)\end{array}\right],$

$f_{nt}=f_n-(2{\mathrm{\ω}}_{ien}+{\mathrm{\ω}}_{enn})\×v_n+\left[\begin{array}{c}0\\ 0\\ -(1-\frac{2heig}{r_e})g\end{array}\right],$

In formula, heig is carrier flying height, ω_ieFor rotational-angular velocity of the earth, g is acceleration of gravity, f_ntFor carrier plus Speed, can be used for speed, position resolves；

Step 5, inertial navigation velocity location resolve: with reference to existing positional information, carry out inertial navigation velocity location resolving, concrete step Rapid inclusion:

Step 501, according to current simulation time t_iWith previous moment simulation time t_i-1, determine simulation step length t, t=t_i- t_i-1；

Step 502, according to carrier acceleration f_nt, simulation step length t, bearer rate is integrated resolve, make v_g=[v_ev_n v_u]^t, then v_g=v_g+f_ntt；

Step 503, the unit of longitude is converted to radian long=long* π/180 by degree；

Step 504, according to bearer rate v_g, simulation step length t, carrier positions are integrated resolve,

Heig=heig+tv_u,

Step 505, by longitude, latitude unit by radian degree of being converted to, long=long*180/ π, lati=lati* 180/π；

Step 6, transformation matrix element extraction: extract coordinate system transformation matrixIn element,I= 1,2,3, j=1,2,3；

Step 7, scale factor calculation: the angle of attack, yaw angle and the seat being provided according to air data system angular transducer Mark system transformation matrixIn element c_ij, calculate the scale factor needing during true air speed calculates, specifically include:

Step 701, the angle of attack being provided air data system angular transducer according to following formula, sideslip angular unit are by spending conversion For radian,

α=α₀* pi/180, β=β₀* pi/180,

In formula, α₀、β₀It is respectively the angle of attack, the yaw angle that air data system angular transducer provides, unit is degree, and α, β divide The angle of attack, the sideslip angle information of radian is not converted to for unit；

Step 702, according to coordinate system transformation matrixIn every element, the angle of attack, yaw angle, calculate true air speed resolve in The scale factor d needing₁=c₃₁*sinβ+c₃₂*cosα*cosβ+c₃₃*sinα*cosβ；

Step 8, true air speed resolve: according to the vector correlation between true air speed, wind speed and ground velocity, in being calculated using true air speed The scale factor d needing₁, sky orientation speed v_uCarry out the resolving of true air speed, v=v_u/d₁, in formula, v is true air speed, when realizing current After carving true air speed resolving, return to step 2, proceed follow-up true air speed and resolve.

The invention has the following beneficial effects:

(1) it is directed to existing combination aircraft dynamics equation and carry out true air speed calculation method to aircraft dynamics with winged control parameter The excessively complicated problem of model, the excessive demand of flight control parameter, calculation method, the present invention uses for reference true air speed, wind speed and ground The vector correlation of speed carries out true air speed resolving, it is to avoid aircraft dynamics model, the use of flight control parameter, to true air speed solution Calculation method is simplified；

(2) for existing, the reduction true air speed resolving of true air speed evaluation method is carried out independently by external information increase quantity of information Property deficiency, there is not the phenomenon of convection current according to Sudden warming in stratosphere, reduce unknown quantity in the present invention, it is to avoid the need to external information Will be it is ensured that the autonomy of system.

Brief description:

Fig. 1 is the principle schematic of the true air speed calculation method of the present invention.

Fig. 2 is the algorithm flow chart of the true air speed calculation method of the present invention.

Fig. 3 is the simulation program structure figure of the true air speed calculation method of the present invention.

Fig. 4 is the result of the true air speed resolving of the true air speed calculation method of the present invention.

Specific embodiment:

Fig. 1 show the principle schematic of true air speed calculation method proposed by the present invention, Fig. 1 .a) in, coordinate axess represent ground Reason coordinate system, transverse axis e represents east orientation, and longitudinal axis n represents north orientation,Represent wind speed,Represent ground velocity,Represent true air speed, ψ represents Course angle, χ_wRepresent wind angle, Fig. 1 .b) in, oxyz represents body axis system,Represent true air speed, α represents the angle of attack, and β represents side Sliding angle.Using the inventive method, at any time, the resolving of true air speed can all be carried out it is not necessary to the accumulation of measured value.

The present invention is used for the true air speed calculation method of atmosphere data/inertial navigation integrated navigation system, and it is related to air Data system, strapdown inertial navigation system, the method feature based on bottom horizontal flow sheet based on upper atmosphere, according to inertial navigation The angle of attack of the ground velocity of system output, attitude angle and air data system output, yaw angle, calculate the ratio between true air speed and ground velocity The example factor, solves true air speed, specifically in the range of inertial navigation system site error and the angle of attack, sideslip measurement error allow True air speed calculation method flow process as shown in Fig. 2 it comprises the following steps:

Step 1, speed position information read: be loaded into the longitude that the inertial navigation system being affected by air data system exports Long, latitude lati, height heig, east orientation speed v_e, north orientation speed v_n, sky orientation speed v_u, longitude, latitude unit are degree, highly Unit is rice, and speed unit is m/s；

Step 2, transformation matrix solve: be loaded into the roll angle γ of inertial navigation system output₀, pitching angle theta₀, course angle ψ₀, Unit is degree, determines that carrier coordinate system is transformed into the transformation matrix of geographic coordinate system according to Euler's horn cupping, specifically includes:

Step 201, the attitude angular unit that inertial navigation system exports is converted to by degree by radian according to following formula,

γ=γ₀* π/180, θ=θ₀* π/180, ψ=ψ₀* π/180,

In formula, γ, θ, ψ are respectively the roll angle that Conversion of measurement unit is radian, the angle of pitch, course angle information；

Step 202, it is transformed into the transformation matrix of carrier coordinate system according to following formula computed geographical coordinates

$c_n^b=\left[\begin{array}{ccc}\cos \mathrm{\γ}\cos \mathrm{\ψ}+\sin \mathrm{\γ}\sin \mathrm{\θ}\sin \mathrm{\ψ}& -\cos \mathrm{\γ}\sin \mathrm{\ψ}+\sin \mathrm{\γ}\sin \mathrm{\θ}\cos \mathrm{\ψ}& -\sin \mathrm{\γ}\cos \mathrm{\θ}\\ \cos \mathrm{\θ}\sin \mathrm{\ψ}& \cos \mathrm{\θ}\cos \mathrm{\ψ}& \sin \mathrm{\θ}\\ \sin \mathrm{\γ}\cos \mathrm{\ψ}-\cos \mathrm{\γ}\sin \mathrm{\θ}\sin \mathrm{\ψ}& -\sin \mathrm{\γ}\cos \mathrm{\ψ}-\cos \mathrm{\γ}\sin \mathrm{\θ}\cos \mathrm{\ψ}& \cos \mathrm{\γ}\cos \mathrm{\θ}\end{array}\right];$

Step 3, design conditions judge: according to sky orientation speed v_uJudged, if | v_u| ＜ 2m/s, return to step 1, if | v_u | >=2m/s, then carry out subsequent step；

Step 4, effective acceleration are extracted: extract acceleration measuring value, extract carrier acceleration, concrete steps include:

Step 401, the unit of latitude is converted to radian lati=lati* π/180 by degree；

Step 402, according to carrier positions, earth radius and earth ellipticity, calculate radius of curvature of the earth,

r_m=r_e(1-2f+3f sin²(lati)), r_n=r_e(1+f sin²(lati))

In formula, r_e, f be respectively earth radius, earth ellipticity, r_m、r_nRadius of curvature of the earth needed for inertial reference calculation；

Step 403, according to transformation matrixAccelerometer output is transformed under navigation system,In formula, f_b、 f_nIt is respectively body system, the specific force navigating under system；

Step 404, the harmful acceleration removing in specific force, extract carrier acceleration, resolve for speed, position,

${\mathrm{\ω}}_{enn}=\left[\begin{array}{c}-\frac{v_n}{(r_m+heig)}\\ \frac{v_e}{(r_n+heig)}\\ \frac{v_e\tan \left(lati\right)}{(r_n+heig)}\end{array}\right],{\mathrm{\ω}}_{ien}=\left[\begin{array}{c}0\\ {\mathrm{\ω}}_{ie}\cos \left(lati\right)\\ {\mathrm{\ω}}_{ie}\sin \left(lati\right)\end{array}\right],$

$f_{nt}=f_n-(2{\mathrm{\ω}}_{ien}+{\mathrm{\ω}}_{enn})\×v_n+\left[\begin{array}{c}0\\ 0\\ -(1-\frac{2heig}{r_e})g\end{array}\right],$

In formula, heig is carrier flying height, ω_ieFor rotational-angular velocity of the earth, g is acceleration of gravity, f_ntFor carrier plus Speed, can be used for speed, position resolves；

Step 5, inertial navigation velocity location resolve: with reference to existing positional information, carry out inertial navigation velocity location resolving, concrete step Rapid inclusion:

Step 501, according to current simulation time t_iWith previous moment simulation time t_i-1, determine simulation step length t, t=t_i- t_i-1；

Step 502, according to carrier acceleration f_nt, simulation step length t, bearer rate is integrated resolve, make v_g=[v_ev_n v_u]^t, then v_g=v_g+f_ntt；

Step 503, the unit of longitude is converted to radian long=long* π/180 by degree；

Step 504, according to bearer rate v_g, simulation step length t, carrier positions are integrated resolve,

Heig=heig+tv_u,

Step 505, by longitude, latitude unit by radian degree of being converted to, long=long*180/ π, lati=lati* 180/π；

Step 6, transformation matrix element extraction: extract coordinate system transformation matrixIn element,I= 1,2,3, j=1,2,3；

Step 7, scale factor calculation: the angle of attack, yaw angle and the seat being provided according to air data system angular transducer Mark system transformation matrixIn element c_ij, calculate the scale factor needing during true air speed calculates, specifically include:

Step 701, the angle of attack being provided air data system angular transducer according to following formula, sideslip angular unit are by spending conversion For radian,

α=α₀* pi/180, β=β₀* pi/180,

In formula, α₀、β₀It is respectively the angle of attack, the yaw angle that air data system angular transducer provides, unit is degree, and α, β divide The angle of attack, the sideslip angle information of radian is not converted to for unit；

Step 702, according to coordinate system transformation matrixIn every element, the angle of attack, yaw angle, calculate true air speed resolve in The scale factor d needing₁=c₃₁*sinβ+c₃₂*cosα*cosβ+c₃₃*sinα*cosβ；

Step 8, true air speed resolve: according to the vector correlation between true air speed, wind speed and ground velocity, in being calculated using true air speed The scale factor d needing₁, sky orientation speed v_uCarry out the resolving of true air speed, v=v_u/d₁, in formula, v is true air speed, when realizing current After carving true air speed resolving, return to step 2, proceed follow-up true air speed and resolve.

In order to evaluate the performance of true air speed calculation method proposed by the present invention, devise simulated program, structure such as Fig. 3 institute Show, this simulated program comprises the following steps:

(1) flight simulation software is carried out with flying condition setting (including wind speed, wind angle etc.)；

(2) carry out flight simulation using flight simulation software, generate flying quality and (include inertial guidance data, atmospheric environment ginseng Number, air-flow angular data etc.)；

(3) it is based on inertial guidance data (including attitude angle, ground velocity), air-flow angular data (including the angle of attack, yaw angle) carries out vacuum Speed resolves, and is compared with real vacuum speed.

Experimental result as shown in figure 4, showing that the true air speed calculation result of the present invention and real vacuum speed essentially coincide, error Average is 0.3m/s, max value of error within 1m/s it was demonstrated that the present invention according to true air speed, wind speed and ground vector relation, The transformation relation of coordinate system resolves correctness and the effectiveness of true air speed method.

The above is only the preferred embodiment of the present invention it is noted that ordinary skill people for the art For member, some improvement can also be made under the premise without departing from the principles of the invention, these improvement also should be regarded as the present invention's Protection domain.

Claims (1)

1. a kind of true air speed calculation method for atmosphere data/inertial navigation integrated navigation system, methods described is related to greatly Gas data system, strapdown inertial navigation system it is characterised in that: comprise the following steps

Step 1, speed position information read: be loaded into the longitude that the inertial navigation system being affected by air data system exports Long, latitude lati, height heig, east orientation speed v_e, north orientation speed v_n, sky orientation speed v_u, longitude, latitude unit are degree, highly Unit is rice, and speed unit is m/s；

Step 2, transformation matrix solve: be loaded into the roll angle γ of inertial navigation system output₀, pitching angle theta₀, course angle ψ₀, unit For degree, determine that carrier coordinate system is transformed into the transformation matrix of geographic coordinate system according to Euler's horn cupping, specifically include:

Step 201, the attitude angular unit that inertial navigation system exports is converted to by degree by radian according to following formula,

γ=γ₀* π/180, θ=θ₀* π/180, ψ=ψ₀* π/180,

In formula, γ, θ, ψ are respectively the roll angle that Conversion of measurement unit is radian, the angle of pitch, course angle information；

Step 202, it is transformed into the transformation matrix of carrier coordinate system according to following formula computed geographical coordinates

Step 3, design conditions judge: according to sky orientation speed v_uJudged, if | v_u| ＜ 2m/s, return to step 1, if | v_u|≥ 2m/s, then carry out subsequent step；

Step 4, effective acceleration are extracted: extract acceleration measuring value, extract carrier acceleration, concrete steps include:

Step 401, the unit of latitude is converted to radian lati=lati* π/180 by degree；

Step 402, according to carrier positions, earth radius and earth ellipticity, calculate radius of curvature of the earth,

r_m=r_e(1-2f+3f sin²(lati)), r_n=r_e(1+f sin²(lati))

In formula, r_e, f be respectively earth radius, earth ellipticity, r_m、r_nRadius of curvature of the earth needed for inertial reference calculation；

Step 403, according to transformation matrixAccelerometer output is transformed under navigation system,In formula, f_b、f_nPoint Wei not body system, the specific force navigating under system；

Step 404, make v_g=[v_ev_nv_u]^t, remove the harmful acceleration in specific force, extract carrier acceleration, for speed, position Put resolving,

${\mathrm{\ω}}_{enn}=\left[\begin{array}{c}-\frac{v_n}{(r_m+heig)}\\ \frac{v_e}{(r_n+heig)}\\ \frac{v_e\tan \left(lati\right)}{(r_n+heig)}\end{array}\right],{\mathrm{\ω}}_{ien}=\left[\begin{array}{c}0\\ {\mathrm{\ω}}_{ie}\cos \left(lati\right)\\ {\mathrm{\ω}}_{ie}\sin \left(lati\right)\end{array}\right],$

$f_{nt}=f_n-(2{\mathrm{\ω}}_{ien}+{\mathrm{\ω}}_{enn})\×v_g+\left[\begin{array}{c}0\\ 0\\ -(1-\frac{2heig}{r_e})g\end{array}\right],$

In formula, heig is carrier flying height, ω_ieFor rotational-angular velocity of the earth, g is acceleration of gravity, f_ntFor carrier acceleration, Can be used for speed, position resolves；

Step 5, inertial navigation velocity location resolve: with reference to existing positional information, carry out inertial navigation velocity location resolving, concrete steps bag Include:

Step 501, according to current simulation time t_iWith previous moment simulation time t_i-1, determine simulation step length t, t=t_i-t_i-1；

Step 502, according to carrier acceleration f_nt, simulation step length t, bearer rate is integrated resolve, then v_g=v_g+f_ntt；

Step 503, the unit of longitude is converted to radian long=long* π/180 by degree；

Step 504, according to bearer rate v_g, simulation step length t, carrier positions are integrated resolve,

Heig=heig+tv_u,

Step 505, by longitude, latitude unit by radian degree of being converted to, long=long*180/ π, lati=lati*180/ π；

Step 6, transformation matrix element extraction: extract coordinate system transformation matrixIn element,I=1,2, 3, j=1,2,3；

Step 7, scale factor calculation: the angle of attack, yaw angle and the coordinate system being provided according to air data system angular transducer Transformation matrixIn element c_ij, calculate the scale factor needing during true air speed calculates, specifically include:

Step 701, according to following formula, by air data system angular transducer, the angle of attack providing, sideslip angular unit are converted to arc by degree Degree,

α=α₀* pi/180, β=β₀* pi/180,

In formula, α₀、β₀It is respectively the angle of attack, the yaw angle that air data system angular transducer provides, unit is degree, and α, β are respectively Conversion of measurement unit is the angle of attack of radian, sideslip angle information；

Step 702, according to coordinate system transformation matrixIn every element, the angle of attack, yaw angle, calculate true air speed resolve in need Scale factor d₁=c₃₁*sinβ+c₃₂*cosα*cosβ+c₃₃*sinα*cosβ；

Step 8, true air speed resolve: according to the vector correlation between true air speed, wind speed and ground velocity, need in being calculated using true air speed Scale factor d₁, sky orientation speed v_uCarry out the resolving of true air speed, v=v_u/d₁, in formula, v is true air speed, realizes current time true After air speed resolves, return to step 2, proceed follow-up true air speed and resolve.