A method for quickly determining the safety boundary of different attack angles by air rudder control

Abstract

The present invention relates to a method for quickly determining the safety boundary of different attack angles by air rudder control, comprising: based on the longitudinal control capability of the aircraft, taking into account the aerodynamic and center of mass deviations to obtain the longitudinal trim rudder deviation, and determining the longitudinal available angle of attack range of the aircraft [α 1min ,α 1max ]; Based on the lateral control capability of the aircraft, taking into account the aerodynamic and center of mass deviations, the lateral control closed-loop stability parameter LCDP is obtained to determine the lateral available angle of attack range of the aircraft [α 2min ,α 2max ]; the above longitudinal available angle of attack range [α 1min ,α 1max ] and the lateral available angle of attack range [α 2min ,α 2max ], find the intersection and determine the available attack angle range of the aircraft [α min ,α max ].

Description

Technical Field

[0001] The present invention relates to a safe control boundary of an aircraft which relies on air rudder control and can stably and smoothly control the aircraft under different angles of attack. Background Art

[0002] The third stage boost phase of the carrier usually adopts swing jet control. Since the engine loses control ability after being exhausted and shut down, the third stage boost phase usually adopts low or zero angle of attack flight. Therefore, the carrier and the aircraft usually take over at a low angle of attack.

[0003] Aircraft controlled by air rudders have a wide flight profile. When the center of mass is fixed, the aircraft is mainly controlled at high altitude and high Mach with a large angle of attack and at low altitude and low Mach with a small angle of attack. However, the aircraft is faced with the problem that the air rudders cannot stably control the small angle of attack at high altitude and high Mach. Although the control problem of small angles of attack can be solved by configuring a suitable attitude control power system on the aircraft, the addition of an additional attitude control power system increases the mass and design complexity of the aircraft, thus restricting the improvement of the overall performance of the aircraft.

[0004] If an appropriate angular velocity can be provided when the carrier separates from the aircraft, the aircraft can rely on this angular velocity to quickly transition to the available angle of attack range, so that the aircraft can be stably controlled. Based on this premise, this method proposes a method for quickly determining the safety boundary at different angles of attack for control based on air rudders, ensuring that the demonstration plan is quickly closed. Summary of the invention

[0005] The technical problem solved by the present invention is: to propose a method for quickly determining the safety boundary at different attack angles by relying on air rudder control. According to this method, different angular velocity ranges that different attack angles can adapt to can be quickly determined, and the intersection with the angular velocity range that can be provided by separation can be obtained, so as to quickly close the demonstration plan for stable aircraft control.

[0006] The technical solution of the present invention is: a method for quickly determining the safety boundary of different attack angles by air rudder control, comprising:

[0007] Based on the longitudinal control capability of the aircraft, the longitudinal trim rudder deviation is obtained by considering the aerodynamic and center of mass deviations. According to the longitudinal physical rudder deviation range, the longitudinal available angle of attack range of the aircraft is determined [α 1min ,α 1max ];

[0008] Based on the lateral control capability of the aircraft, taking into account the aerodynamic and center of mass deviations, the lateral control closed-loop stability parameter LCDP is obtained to determine the available lateral attack angle range of the aircraft [α 2min ,α 2max ];

[0009] The above available longitudinal attack angle range [α 1min ,α 1max ] and the lateral available angle of attack range [α 2min ,α 2max ], find the intersection and determine the available attack angle range of the aircraft [α min ,α max ].

[0010] Preferably, LCDP<-5e-4.

[0011] Preferably, the method further comprises:

[0012] According to the minimum value α of the controllable angle of attack of the aircraft min , determine the lower limit of the initial pitch angular velocity ω that the aircraft can stably control 0_m i n ;

[0013] According to the maximum value of the controllable attack angle of the aircraft α max , determine the upper limit of the initial pitch angular velocity ω that the aircraft can stably control 0_max ;

[0014] Then determine the longitudinal angular velocity boundary [ω 0_min ,ω 0_max ].

[0015] Preferably, the lower limit ω of the initial pitch angular velocity allowed for stable control of the aircraft is determined by: 0_min :

[0016] First, establish the relationship between the initial value of angular velocity ω0 and the allowable deceleration time t2:

[0017]

[0018] In the above time course, the change of the angle of attack needs to reach the minimum controllable angle of attack, which is calculated according to the following formula: 0_min :

[0019]

[0020] Preferably, the upper limit ω of the initial pitch angular velocity allowed for stable control of the aircraft is determined by: 0_max :

[0021] Establish the relationship between the initial value of angular velocity and the allowable deceleration time:

[0022]

[0023] In the above time course, the change of the angle of attack needs to reach the upper limit of the controllable angle of attack boundary, and ω is calculated according to the following formula: 0_max :

[0024]

[0025] Preferably, when the angular velocity range of the aircraft is ω0 ≥ ω 0_min When the aircraft raises its head with maximum capacity, the angle of attack is at least increased to the minimum available angle of attack α when the angular velocity decelerates to zero. min Place.

[0026] Preferably, when the angular velocity range of the aircraft is ω0≤ω 0_max When the aircraft lowers its head with maximum capability, the angle of attack is decelerated to zero, or at a small negative angle of attack, the angle of attack is pulled up to the maximum available angle of attack α max .

[0027] A system for quickly determining the safety margin of different attack angles by air rudder control, comprising:

[0028] The first module, based on the longitudinal control capability of the aircraft, considers the aerodynamic and center of mass deviations to obtain the longitudinal trim rudder deviation, and determines the longitudinal available angle of attack range of the aircraft [α 1min ,α 1max ];

[0029] The second module, based on the lateral control capability of the aircraft, takes into account the aerodynamic and center of mass deviations, obtains the lateral control closed-loop stability parameter LCDP, and determines the available lateral attack angle range of the aircraft [α 2min ,α 2max ];

[0030] The third module converts the longitudinal available angle of attack range [α 1min ,α 1max ] and the lateral available angle of attack range [α 2min ,α 2max ], find the intersection and determine the available attack angle range of the aircraft [α min ,α max ].

[0031] Preferably, the system further comprises

[0032] The fourth module is based on the minimum value α of the controllable angle of attack of the aircraft min , determine the lower limit of the initial pitch angular velocity ω that the aircraft can stably control 0_min ;

[0033] The fifth module is based on the maximum value α of the controllable angle of attack of the aircraft max , determine the upper limit of the initial pitch angular velocity ω that the aircraft can stably control 0_max ;

[0034] The sixth module determines the longitudinal angular velocity boundary [ω] at which the aircraft can be safely controlled based on the results of the fourth and fifth modules. 0_min ,ω 0_max ].

[0035] Preferably, the fourth module determines the lower boundary ω according to the following equations 0_min :

[0036]

[0037] The fifth module determines the upper boundary ω according to the following set of equations 0_max :

[0038]

[0039] in:

[0040] ω0——The initial angular velocity of the aircraft pitch, in rad / s;

[0041] C m (δ m =0)——the pitch moment coefficient of the aircraft in the zero rudder deflection state, dimensionless;

[0042] C m (δ m =δ m_max )——the pitch moment coefficient of the aircraft in the pitch positive limit rudder deflection state, dimensionless;

[0043] t1——the required servo response time for issuing the pitch limit rudder deflection command, in seconds;

[0044] t2——allowable deceleration time, unit: s;

[0045] α min ——The minimum value of the available angle of attack, in rad.

[0046] α max ——The maximum value of the available angle of attack, in rad.

[0047] α0——The initial angle of attack of the aircraft, in rad.

[0048] The beneficial effect of the present invention compared with the prior art is that the present invention can quickly determine the adaptive angular velocity range of the launch control capability at different angles of attack through a method for quickly determining the safety boundary of the air rudder launch control at different angles of attack, and maximize the launch control capability of the aircraft, which is conducive to the rapid demonstration of the overall plan. DETAILED DESCRIPTION

[0049] The present invention will be further described below in conjunction with embodiments, which are as follows:

[0050] (1) Based on the longitudinal control capability of the aircraft, according to the longitudinal physical rudder deviation range constraint, and taking into account the aerodynamic and center of mass deviation, determine the longitudinal available angle of attack range of the aircraft [α 1min ,α 1max ];

[0051] (2) Based on the lateral control capability, according to the lateral control closed-loop stability parameter LCDP, after considering the aerodynamic and center of mass deviations, the available lateral angle of attack range of the aircraft [α 2min ,α 2max ],

[0052]

[0053] in:

[0054] ——derivative of the yaw moment coefficient with respect to the sideslip angle, unit: 1 / °;

[0055] ——derivative of the rolling moment coefficient with respect to the sideslip angle, unit: 1 / °;

[0056] ——derivative of yaw moment coefficient with respect to differential rudder, unit: 1 / °;

[0057] ——derivative of the rolling moment coefficient with respect to the differential rudder, unit: 1 / °;

[0058] J x ——The moment of inertia of the aircraft around the x-axis, in kg.m2

[0059] J y ——The moment of inertia of the aircraft around the y-axis, in kg.m2

[0060] J xy ——The moment of inertia of the aircraft around the xoy plane of the coordinate system, unit: kg.m2

[0061] (3) Based on the determined longitudinal available angle of attack range [α 1min ,α 1max ], and the available angle of attack range [α 2min ,α 2max ], find the intersection and determine the available attack angle range of the aircraft [α min ,α max ]

[0062] [α min ,α max ]=[α 1min ,α 1max ]∩[α 2min ,α 2max ]

[0063] (4) According to the determined minimum value α of the controllable angle of attack of the aircraft min , determine the lower limit of the initial pitch angular velocity ω that the aircraft can stably control 0_min :

[0064] Considering the response time of the servo mechanism and the change in the aircraft's attitude after the servo mechanism outputs the required rudder deviation to correct the attitude, in order to ensure the safe take-off and control of the aircraft, the aircraft needs to raise its head with maximum capacity, ensure that the angular velocity decelerates to zero, and the angle of attack is at least increased to the minimum controllable angle of attack.

[0065] First, establish the relationship between the initial value of angular velocity and the allowable deceleration time:

[0066]

[0067] In the above time course, the change in angle of attack needs to reach the minimum controllable angle of attack:

[0068]

[0069] in:

[0070] ω0——The initial angular velocity of the aircraft pitch, in rad / s;

[0071] t2——allowable deceleration time, unit: s;

[0072] C m (δ m =0)——the pitch moment coefficient of the aircraft in the zero rudder deflection state, dimensionless;

[0073] C m (δ m =δ m_min )——the pitch moment coefficient of the aircraft in the state of negative pitch limit rudder deflection, dimensionless;

[0074] t1——the required servo response time for issuing the pitch limit negative rudder deflection command, in seconds;

[0075] α min ——The minimum value of the available angle of attack, in rad.

[0076] α0——The initial angle of attack of the aircraft, in rad. ;

[0077] (5) According to the maximum value α of the controllable attack angle of the aircraft max , determine the upper limit of the initial pitch angular velocity ω that the aircraft can stably control 0_max ;

[0078] Considering the response time of the servo mechanism and the change in the aircraft's attitude after the servo mechanism outputs the required rudder deviation to correct the attitude, in order to ensure the safe control of the aircraft, the aircraft needs to lower its head with maximum ability to ensure that the angular velocity decelerates to zero and the angle of attack drops to the maximum controllable angle of attack.

[0079] Establish the relationship between the initial value of angular velocity and the allowable deceleration time:

[0080]

[0081] In the above time course, the change of the angle of attack needs to reach the controllable angle of attack boundary

[0082]

[0083] in:

[0084] t2——allowable deceleration time, unit: s;

[0085] α max ——The maximum value of the available angle of attack, in rad.

[0086] (6) Based on the angular velocity boundary determined above, determine the longitudinal angular velocity boundary [ω 0_min ,ω 0_max ]

[0087] When the angular velocity range of the aircraft ω0 ≥ ω 0_min When the aircraft raises its head with maximum capacity, the angle of attack is at least increased to the minimum available angle of attack α when the angular velocity decelerates to zero. min At ω0, the minimum angular velocity allowed by the aircraft is obtained. 0_min .

[0088] When the angular velocity range of the aircraft is ω0≤ω 0_max When the aircraft lowers its head with maximum capability, the angle of attack is decelerated to zero, or at a small negative angle, the angle of attack is pulled up to the maximum available angle of attack α max , get the minimum angular velocity initial value ω0=ω allowed by the aircraft 0_max .

[0089] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

[0090] Parts not described in detail in the present invention belong to common knowledge of those skilled in the art.

Claims

1. A method for quickly determining the safety margin of different attack angles by air rudder control, characterized in that include: Based on the longitudinal control capability of the aircraft, the longitudinal trim rudder deviation is obtained by considering the aerodynamic and center of mass deviations. According to the longitudinal physical rudder deviation range, the longitudinal available angle of attack range of the aircraft is determined [α 1min ,α 1max ]; Based on the lateral control capability of the aircraft, taking into account the aerodynamic and center of mass deviations, the lateral control closed-loop stability parameter LCDP is obtained to determine the available lateral attack angle range of the aircraft [α 2min ,α 2max ]; The above available longitudinal attack angle range [α 1min ,α 1max ] and the lateral available angle of attack range [α 2min ,α 2max ], find the intersection and determine the available attack angle range of the aircraft [α min ,α max ]; The invention is characterized in that: According to the minimum value α of the controllable angle of attack of the aircraft min , determine the lower limit of the initial pitch angular velocity ω that the aircraft can stably control 0_min ; According to the maximum value of the controllable attack angle of the aircraft α max , determine the upper limit of the initial pitch angular velocity ω that the aircraft can stably control 0_max ; Then determine the longitudinal angular velocity boundary [ω 0_min ,ω 0_max ]; It is characterized in that the lower limit ω of the initial pitch angular velocity allowed for stable start-up of the aircraft is determined by the following method 0_min : First, establish the relationship between the initial value of angular velocity ω0 and the allowable deceleration time t2: In the above time course, the change of the angle of attack needs to reach the minimum controllable angle of attack, which is calculated according to the following formula: 0_min : It is characterized in that the upper limit ω of the initial pitch angular velocity allowed for stable start-up of the aircraft is determined by the following method 0_max : Establish the relationship between the initial value of angular velocity and the allowable deceleration time: In the above time course, the change of the angle of attack needs to reach the upper limit of the controllable angle of attack boundary, and ω is calculated according to the following formula: 0_max :

2. The method according to claim 1, characterized in that: LCDP<-5e-4 is required.

3. The method according to claim 1, characterized in that: When the angular velocity range of the aircraft ω0 ≥ ω 0_min When the aircraft raises its head with maximum capacity, the angle of attack is at least increased to the minimum available angle of attack α when the angular velocity decelerates to zero. min Place.

4. The method according to claim 1, characterized in that: When the angular velocity range of the aircraft is ω0≤ω 0_max When the aircraft lowers its head with maximum capability, the angle of attack is decelerated to zero, or at a small negative angle, the angle of attack is pulled up to the maximum available angle of attack α max .

5. A system for quickly determining the safety margin of different attack angles by air rudder control, characterized in that include: The first module, based on the longitudinal control capability of the aircraft, considers the aerodynamic and center of mass deviations to obtain the longitudinal trim rudder deviation, and determines the longitudinal available angle of attack range of the aircraft [α 1min ,α 1max ]; The second module, based on the lateral control capability of the aircraft, takes into account the aerodynamic and center of mass deviations, obtains the lateral control closed-loop stability parameter LCDP, and determines the available lateral attack angle range of the aircraft [α 2min ,α 2max ]; The third module converts the longitudinal available angle of attack range [α 1min ,α 1max ] and the lateral available angle of attack range [α 2min ,α 2max ], find the intersection and determine the available attack angle range of the aircraft [α min ,α max ]; The fourth module is based on the minimum value α of the controllable angle of attack of the aircraft mi n, determine the lower limit of the initial pitch angular velocity ω that the aircraft can stably control 0_min ; The fifth module is based on the maximum value α of the controllable angle of attack of the aircraft max , determine the upper limit of the initial pitch angular velocity ω that the aircraft can stably control 0_max ; The sixth module determines the longitudinal angular velocity boundary [ω] at which the aircraft can be safely controlled based on the results of the fourth and fifth modules. 0_min ,ω 0_max ]; The seventh module determines the lower boundary ω according to the following set of equations 0_min : The eighth module determines the upper boundary ω according to the following set of equations 0_max : in: ω0——The initial angular velocity of the aircraft pitch, in rad / s; C m (δ m =0)——the pitch moment coefficient of the aircraft in the zero rudder deflection state, dimensionless; C m (δ m =δ m_max )——the pitch moment coefficient of the aircraft in the pitch positive limit rudder deflection state, dimensionless; t1——the required servo response time for issuing the pitch limit rudder deflection command, in seconds; t2——allowable deceleration time, unit: s; α mi n——the minimum value of the available angle of attack, in rad; α max ——The maximum value of the available angle of attack, in rad; α0——The initial angle of attack of the aircraft, in rad.

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