A method for constructing a simulation model of an aircraft in inverted flight state

Abstract

This application provides a method for constructing a simulation model of an aircraft in inverted flight state, including: Step 1, defining an equivalent aircraft, redefining the body axis coordinate system so that the equivalent aircraft is the aircraft after the original aircraft has rolled 180°, and converting the negative angle-of-attack aerodynamic characteristics of the original aircraft into the positive angle-of-attack aerodynamic characteristics of the equivalent aircraft; Step 2, transforming the control surfaces involved in the simulation model into the control surfaces of the equivalent aircraft according to the correspondence between the control surfaces of the equivalent aircraft and the original aircraft; Step 3, transforming the aerodynamic model in the simulation model into the aerodynamic forces of the equivalent aircraft according to the correspondence between the aerodynamic forces of the equivalent aircraft and the original aircraft; Step 4, transforming the servo model in the simulation model into the servo model according to the control surface relationship between the original aircraft and the equivalent aircraft, using the control surface commands of the original aircraft as input for the hinge moment model and the servo model, and converting the control surface output commands into control surface commands of the equivalent aircraft before inputting them into the aerodynamic model.

Description

Technical Field

[0001] This application belongs to the field of flight control technology, and specifically relates to a method for constructing a simulation model of an aircraft in inverted flight state. Background Technology

[0002] Aircraft flight states include forward flight and inverted flight. Highly maneuverable aircraft, in particular, frequently enter inverted flight states when performing maneuvers. Therefore, dynamic simulation analysis of inverted flight states is of great significance.

[0003] There are generally two scenarios for aircraft flying inverted. One is that although the aircraft's attitude is reversed, it still flies at a positive angle of attack, such as loop maneuvers or half-roll inverted maneuvers. For simulation analysis of this type of inverted flight, which falls under the analysis of positive angle of attack stability and handling characteristics, the simulation analysis can be performed as if the aircraft were flying normally. The other scenario is that the aircraft's attitude is reversed and it flies at a negative angle of attack, such as an inverted spin. For analysis of this type of inverted flight, the handling and stability of the aircraft at a negative angle of attack should be analyzed.

[0004] In conventional flight simulation analysis, aircraft dynamics models are established based on the definition of the aircraft's forward flight state, specifically its positive angle of attack characteristics. The initial trim of the simulation program must be performed under positive angle of attack conditions. While this nonlinear simulation model based on six-degree-of-freedom dynamics can simulate inverted flight, it is constrained by the initial conditions of the simulation model. The initial simulation must begin in forward flight, requiring maneuvers to induce inverted flight before analysis. This method not only impacts simulation efficiency but also makes it difficult to quantify and evaluate typical flight conditions. Therefore, it is necessary to find a simpler method for simulating and analyzing inverted flight. Summary of the Invention

[0005] The purpose of this application is to provide a method for constructing a simulation model of an aircraft in inverted flight state, so as to solve or alleviate at least one of the problems in the background art.

[0006] This application provides a method for constructing a simulation model of an aircraft in inverted flight state, including:

[0007] Step 1: Define the equivalent aircraft

[0008] The body axis coordinate system is redefined so that the equivalent aircraft is the aircraft after the original aircraft has been rotated 180° in roll attitude, and the negative angle of attack aerodynamic characteristics of the original aircraft are converted into the positive angle of attack aerodynamic characteristics of the equivalent aircraft.

[0009] Step 2, Aircraft control surface change

[0010] The control surfaces involved in the simulation model are transformed into the control surfaces of the equivalent aircraft according to the correspondence between the control surfaces of the equivalent aircraft and the original aircraft.

[0011] Step 3: Aerodynamic model transformation

[0012] The aerodynamic model in the simulation model is transformed into the aerodynamic force of the equivalent aircraft based on the correspondence between the aerodynamic forces of the equivalent aircraft and the original aircraft.

[0013] Step 4: Servo Model Transformation

[0014] The servo model in the simulation model is converted according to the control surface relationship between the original aircraft and the equivalent aircraft. The hinge torque model and servo model are input using the control surface commands of the original aircraft. After the control surface output commands are converted into the control surface commands of the equivalent aircraft, they are input to the aerodynamic model.

[0015] Furthermore, after redefining the body axis coordinate system, the coordinate relationships are as follows:

[0016] x t等效飞机 =x t原飞机

[0017] y t等效飞机 =-y t原飞机

[0018] z t等效飞机 =-z t原飞机

[0019] In the formula, x t原飞机 The original aircraft body axis is in the X direction; y t原飞机 The original aircraft body axis is in the Y direction; z t原飞机 The original aircraft body axis is in the Z direction; x t等效飞机 The equivalent aircraft body axis is in the X direction; y t等效飞机 For the equivalent aircraft body axis in the Y direction; z t等效飞机 The equivalent aircraft body axis is in the Z direction;

[0020] The three-axis moment correspondence between the equivalent aircraft and the original aircraft satisfies the following:

[0021] M x等效飞机 =M x原飞机

[0022] M y等效飞机 =-M y原飞机

[0023] M z等效飞机 =-M z原飞机

[0024] In the formula, M x原飞机 M represents the original aircraft rolling moment. y原飞机 M is the original yaw moment of the aircraft; z原飞机 M represents the original aircraft pitch moment; x等效飞机 M is the equivalent aircraft rolling moment;y等效飞机 M is the equivalent aircraft yaw moment. z等效飞机 This is the equivalent aircraft pitching moment.

[0025] Furthermore, the control surfaces involved include the aircraft ailerons, the aircraft rudder, and the aircraft horizontal stabilizer.

[0026] Furthermore, the correspondence between the ailerons of the equivalent aircraft and the ailerons of the original aircraft is as follows:

[0027] δ xR =-δ′ xL δ xL =-δ′ xR

[0028] In the formula, δ xR The equivalent right aileron deflection; δ xL The equivalent left aileron deflection; δ′ xR The original right aileron deflection; δ′ xL This refers to the original aircraft's left aileron deflection.

[0029] Furthermore, the correspondence between the equivalent aircraft's rudder and the original aircraft's rudder is as follows:

[0030] δ yR =-δ′ yL δ yL =-δ′ yR

[0031] In the formula, δ yR The equivalent right rudder deflection; δ yL The equivalent left rudder deflection of the aircraft; δ' yR The original right rudder deflection; δ' yL This refers to the original left rudder deflection of the aircraft.

[0032] Furthermore, the correspondence between the horizontal stabilizer of the equivalent aircraft and the horizontal stabilizer of the original aircraft is as follows:

[0033] δ zR =-δ′ zL δ zL =-δ′ zR

[0034] In the formula, δ zR The equivalent right horizontal stabilizer deflection of the aircraft; δ zL The equivalent left horizontal stabilizer deflection of the aircraft; δ′ zR The original aircraft's right horizontal stabilizer deviation; δ′ zL This refers to the original aircraft's left horizontal stabilizer deflection.

[0035] Furthermore, the aerodynamic relationship between the equivalent aircraft and the original aircraft is as follows:

[0036] α 原飞机 =-α 等效飞机

[0037] β 原飞机 =-β 等效飞机

[0038] δ x原飞机 =δ x等效飞机

[0039] δ y原飞机 =-δ y等效飞机

[0040] δ z原飞机 =-δ z等效飞机

[0041] C y原飞机 =-C y等效飞机

[0042] C x原飞机 =C x等效飞机

[0043] C z原飞机 =-C z等效飞机

[0044] m x原飞机 =m x等效飞机

[0045] m y原飞机 =-m y等效飞机

[0046] m z原飞机 =m z等效飞机

[0047] In the formula, α 原飞机 This is the original angle of attack of the aircraft; β 原飞机 This represents the original aircraft sideslip angle; δ x原飞机 The original aircraft aileron deflection; δ y原飞机 The original aircraft rudder deflection; δ z原飞机 The original aircraft horizontal stabilizer deflection; C y原飞机 C represents the original aircraft lift coefficient. x原飞机 C represents the original aircraft drag coefficient. z原飞机 m represents the original aircraft side force coefficient. x原飞机 The original aircraft rolling moment coefficient; m y原飞机 The original aircraft yaw moment coefficient; m z原飞机 This is the original aircraft pitch moment coefficient;

[0048] α 等效飞机 β is the equivalent angle of attack of the aircraft. 等效飞机 δ is the equivalent aircraft sideslip angle; x等效飞机 For equivalent aircraft aileron deflection; δ y等效飞机δ is the equivalent aircraft rudder deflection. z等效飞机 C is the equivalent aircraft horizontal stabilizer deflection; y等效飞机 C is the equivalent aircraft lift coefficient. x等效飞机 C is the equivalent aircraft drag coefficient. z等效飞机 m is the equivalent aircraft side force coefficient. x等效飞机 The equivalent aircraft rolling moment coefficient; m y等效飞机 The equivalent aircraft yaw moment coefficient; m z等效飞机 This is the equivalent aircraft pitching moment coefficient.

[0049] The method of this application is based on the equivalent transformation of the aerodynamic forces of the original aircraft using an equivalent aircraft. It uses a simulation environment based on positive flight to perform simulation. When obtaining the same aircraft dynamic characteristics, the simulation setup is simple and avoids the difficulty of directly analyzing the stability and handling of the aircraft under negative angle of attack conditions. Attached Figure Description

[0050] To more clearly illustrate the technical solutions provided in this application, the accompanying drawings will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application.

[0051] Figure 1 The flowchart illustrates the method for constructing a simulation model of the aircraft in inverted flight state as described in this application.

[0052] Figure 2 This diagram illustrates the relationship between the angles of attack of an aircraft flying forward and backward.

[0053] Figure 3 This diagram illustrates the relationship between the sideslip angles of an aircraft flying forward and backward. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings.

[0055] like Figure 1 As shown, the simulation model construction method for an aircraft in inverted flight state provided in this application specifically includes the following steps:

[0056] 1. Define the equivalent aircraft

[0057] like Figure 1 As shown, the body axis coordinate system is first redefined, and the equivalent aircraft is defined as the aircraft after the original aircraft has been rotated 180°. By redefining the body axis coordinate system, the negative angle of attack aerodynamic characteristics of the original aircraft can be converted into the positive angle of attack aerodynamic characteristics of the equivalent aircraft.

[0058] The redefined body coordinate system has the following relationship with the original body coordinate system:

[0059] xt等效飞机 =x t原飞机

[0060] y t等效飞机 =-y t原飞机

[0061] z t等效飞机 =-z t原飞机 .

[0062] The correspondence between the three-axis moments of the equivalent aircraft and the original aircraft is transformed into:

[0063] M x等效飞机 =M x原飞机

[0064] M y等效飞机 =-M y原飞机

[0065] M z等效飞机 =-M z原飞机 .

[0066] 2. Aircraft control surface changes

[0067] The control surfaces or command parameters involved in the simulation model are transformed into the control surfaces of the equivalent aircraft based on the correspondence between the control directions of the equivalent aircraft and the original aircraft.

[0068] The aforementioned control surfaces include the aircraft ailerons, the aircraft rudder, and the aircraft horizontal stabilizer.

[0069] The correspondence between the ailerons of the equivalent aircraft and the original aircraft is: δ xR =-δ′ xL δ xL =-δ′ xR Thus, if the original aircraft rolls to the left: δ xR >0, δ xL <0, the equivalent aircraft control surface is: δ' xR >0, δ' xL <0 left roll, consistent with the original aircraft handling.

[0070] The correspondence between the rudder of the equivalent aircraft and the original aircraft is: δ yR =-δ′ yL δ yL =-δ′ yR Thus, if the original aircraft yaws to the left: δ yR <0, δ yL <0, the equivalent aircraft control surface is: δ' yR >0, δ' yL >0 yaw to the left, consistent with the original aircraft handling characteristics.

[0071] The correspondence between the horizontal stabilizer of the equivalent aircraft and the original aircraft is: δ zR =-δ′zL δ zL =-δ′ zR Thus, if the original aircraft pitches down: δ zR >0, δ zL >0, the equivalent aircraft control surface is: δ' zR <0, δ' zL <0 pitch up, consistent with the original aircraft's handling characteristics.

[0072] 3. Aerodynamic model transformation

[0073] The aerodynamic model in the simulation model is transformed into the aerodynamic force of the equivalent aircraft based on the correspondence between the aerodynamic forces of the equivalent aircraft and the original aircraft.

[0074] Specifically, in the original aircraft aerodynamic model input parameters, the angle of attack α 原飞机 =-α 等效飞机 Sideslip angle β 原飞机 =-β 等效飞机 Aileron δ x原飞机 =δ x等效飞机 rudder δ y原飞机 =-δ y等效飞机 , flat tail δ z原飞机 =-δ z等效飞机 .

[0075] In the original aircraft aerodynamic model output parameters: lift C y原飞机 =-C y等效飞机 Resistance C x原飞机 =C x等效飞机 Lateral force C z原飞机 =-C z等效飞机 Rolling torque coefficient m x原飞机 =m x等效飞机 Yaw moment coefficient m y原飞机 =-m y等效飞机 Pitch moment coefficient, m z原飞机 =m z等效飞机 .

[0076] 4. Servo Model Transformation

[0077] When the control surface commands calculated by the control law are transmitted to the servo model, they are converted according to the control surface relationship between the original aircraft and the equivalent aircraft. The horizontal stabilizer command δ in the pitch direction is... z Transformed into δ zc =δ zRc =δ zLc After step 2, the original aircraft control surface commands are transformed and entered into the corresponding servo model. The servo output commands are then entered into the aircraft hinge moment model as the control surface input values. The angle of attack and sideslip angle inputs of the hinge moment model are the angle of attack α. 原飞机 =-α 等效飞机 Sideslip angle β 原飞机=-β 等效飞机 The hinge torque output is fed into the servo model as feedback; the servo's control surface outputs the command δ. zR舵机 δ zR舵机 The transformation in step 2 converts the data into equivalent aircraft control surface output commands, which are then fed into the aerodynamic model to calculate the aircraft's aerodynamic forces and aerodynamic moments.

[0078] The simulation model construction method for aircraft inverted flight proposed in this invention can transform the analysis of negative angle of attack in inverted flight into the analysis of positive angle of attack in normal flight by transforming the aircraft coordinate axis, effectively solving the problem of initial value setting in simulation. Furthermore, the stability and maneuverability analysis of inverted flight can be performed using the linearized small perturbation theory based on normal flight.

[0079] Existing methods for analyzing the stability and controllability of aircraft inverted flight are mainly nonlinear simulation analyses. They require starting with a normal flight simulation and setting up maneuvers before entering the inverted flight phase. This approach is simplistic and involves complex simulation setups. In contrast, this method uses an equivalent aircraft to perform an equivalent transformation of the original aircraft's aerodynamics and employs a simulation environment based on normal flight. This simplifies the simulation setup while obtaining the same aircraft dynamic characteristics, avoiding the difficulties of directly analyzing aircraft stability and controllability under negative angle-of-attack conditions.

[0080] Furthermore, the analysis theories of aircraft stability and handling are all based on positive angle of attack. Moreover, the analysis of aircraft stability and handling first requires trim calculations, followed by linear small disturbance analysis. These theories are all based on positive flight. Using this method, the analysis of aircraft stability and handling at negative angle of attack can be transformed into the analysis of characteristics at positive angle of attack, allowing for direct trim calculations and linear small disturbance analysis.

[0081] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0082] Symbol explanation:

[0083] x t The X-axis is the axis of the aircraft.

[0084] y t The Y-axis is the axis of the aircraft.

[0085] z t The Z-axis is the axis of the aircraft.

[0086] M x This refers to the rolling torque;

[0087] M y This is the yaw moment;

[0088] M z For pitching moment;

[0089] δ xR Right aileron deflection;

[0090] δ xL Left aileron deflection;

[0091] δ yR This refers to the right rudder deflection;

[0092] δ yL Left rudder deflection;

[0093] δ zR The right tail deviation;

[0094] δ zL Left tail deviation;

[0095] α is the angle of attack;

[0096] β is the sideslip angle;

[0097] C y The lift coefficient;

[0098] C x This is the drag coefficient;

[0099] C z This is the lateral force coefficient;

[0100] m x This is the rolling moment coefficient;

[0101] m y This is the yaw moment coefficient;

[0102] m z This is the pitch moment coefficient;

[0103] Among them, the subscript "original aircraft" indicates the corresponding parameters of the original aircraft, and the subscript "equivalent aircraft" indicates the corresponding parameters of the equivalent aircraft.

Claims

1. A method for constructing a simulation model of an aircraft in inverted flight state, characterized in that, include: Step 1: Define the equivalent aircraft The body-axis coordinate system is redefined so that the equivalent aircraft is the aircraft after the original aircraft has been rotated 180° in roll attitude. The negative angle-of-attack aerodynamic characteristics of the original aircraft are converted into the positive angle-of-attack aerodynamic characteristics of the equivalent aircraft. After redefining the body-axis coordinate system, the coordinate relationships are as follows: X 等效飞机 =X t原飞机 and t等效飞机 =-y t原飞机 WITH t等效飞机 =-Z t原飞机 In the formula, x t原飞机 The original aircraft body axis is in the X direction; y t原飞机 The original aircraft body axis is in the Y direction; z t原飞机 The original aircraft body axis is in the Z direction; x t等效飞机 The equivalent aircraft body axis is in the X direction; y t等效飞机 For the equivalent aircraft body axis in the Y direction; z t等效飞机 The equivalent aircraft body axis is in the Z direction; The three-axis moment correspondence between the equivalent aircraft and the original aircraft satisfies the following: M x等效飞机 =M x原飞机 M y等效飞机 =-M y原飞机 M z等效飞机 =-M z原飞机 In the formula, M x原飞机 M represents the original aircraft rolling moment. y原飞机 M is the original yaw moment of the aircraft; z原飞机 M represents the original aircraft pitch moment; x等效飞机 M is the equivalent aircraft rolling moment; y等效飞机 M is the equivalent aircraft yaw moment. z等效飞机 This is the equivalent aircraft pitching moment; Step 2, Aircraft control surface change The control surfaces involved in the simulation model are transformed into the control surfaces of the equivalent aircraft according to the correspondence between the control surfaces of the equivalent aircraft and the original aircraft. Step 3: Aerodynamic model transformation The aerodynamic model in the simulation model is transformed into the aerodynamic force of the equivalent aircraft based on the correspondence between the aerodynamic forces of the equivalent aircraft and the original aircraft. Step 4: Servo Model Transformation The servo model in the simulation model is converted according to the control surface relationship between the original aircraft and the equivalent aircraft. The hinge torque model and servo model are input using the control surface commands of the original aircraft. After the control surface output commands are converted into the control surface commands of the equivalent aircraft, they are input to the aerodynamic model.

2. The method for constructing a simulation model of an aircraft in inverted flight state as described in claim 1, characterized in that, The control surfaces involved include the aircraft ailerons, the aircraft rudder, and the aircraft horizontal stabilizer.

3. The method for constructing a simulation model of an aircraft in inverted flight state as described in claim 2, characterized in that, The correspondence between the ailerons of the equivalent aircraft and the ailerons of the original aircraft is as follows: d xR =-d' xL ,d xL =-d' xR In the formula, δ xR The equivalent right aileron deflection; δ xL The equivalent left aileron deflection; δ′ xR The original right aileron deflection; δ′ xL This refers to the original aircraft's left aileron deflection.

4. The method for constructing a simulation model of an aircraft in inverted flight state as described in claim 2, characterized in that, The correspondence between the rudder of the equivalent aircraft and the rudder of the original aircraft is as follows: d yR =-δ′ yL ,d yL =-δ′ yR In the formula, δ yR The equivalent right rudder deflection; δ yL The equivalent left rudder deflection of the aircraft; δ' yR The original right rudder deflection; δ' yL This refers to the original left rudder deflection of the aircraft.

5. The method for constructing a simulation model of an aircraft in inverted flight state as described in claim 2, characterized in that, The correspondence between the horizontal stabilizer of the equivalent aircraft and the horizontal stabilizer of the original aircraft is as follows: d zR =-δ′ zL ,d zL =-δ′ zR In the formula, δ zR The equivalent right horizontal stabilizer deflection of the aircraft; δ zL The equivalent left horizontal stabilizer deflection of the aircraft; δ′ zR The original aircraft's right horizontal stabilizer deviation; δ′ zL This refers to the original aircraft's left horizontal stabilizer deflection.

6. The method for constructing a simulation model of an aircraft in inverted flight state as described in claim 1, characterized in that, The aerodynamic relationship between the equivalent aircraft and the original aircraft is as follows: α 原飞机 ＝-α 等效飞机 β 原飞机 ＝-β 等效飞机 d x原飞机 =d x等效飞机 d y原飞机 =-d y等效飞机 d z原飞机 =-d z等效飞机 C y原飞机 =-C y等效飞机 C x原飞机 =C x等效飞机 C z原飞机 =-C z等效飞机 m x原飞机 =m x等效飞机 m y原飞机 =-m y等效飞机 m z原飞机 =m 等效飞机 In the formula, α 原飞机 This is the original angle of attack of the aircraft; β 原飞机 This represents the original aircraft sideslip angle; δ x原飞机 The original aircraft aileron deflection; δ y原飞机 The original aircraft rudder deflection; δ z原飞机 The original aircraft horizontal stabilizer deflection; C y原飞机 C represents the original aircraft lift coefficient. x原飞机 C represents the original aircraft drag coefficient. z原飞机 m represents the original aircraft side force coefficient. x原飞机 The original aircraft rolling moment coefficient; m y原飞机 The original aircraft yaw moment coefficient; m z原飞机 This is the original aircraft pitch moment coefficient; α 等效飞机 β is the equivalent angle of attack of the aircraft. 等效飞机 δ is the equivalent aircraft sideslip angle; x等效飞机 For equivalent aircraft aileron deflection; δ y等效飞机 δ is the equivalent aircraft rudder deflection. z等效飞机 C is the equivalent aircraft horizontal stabilizer deflection; y等效飞机 C is the equivalent aircraft lift coefficient. x等效飞机 C is the equivalent aircraft drag coefficient. z等效飞机 m is the equivalent aircraft side force coefficient. x等效飞机 The equivalent aircraft rolling moment coefficient; m y等效飞机 The equivalent aircraft yaw moment coefficient; m z等效飞机 This is the equivalent aircraft pitching moment coefficient.

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