Method and device for calculating rudder deviation required by unit normal overload of statically unstable aircraft
By constructing a stability-enhancing control law and aerodynamic model, and using small-disturbance linearized equations and state-space matrices to calculate the rudder deflection required for a unit normal overload of a statically unstable aircraft, the problem of rudder deflection calculation for statically unstable aircraft under disturbances is solved, and low-cost handling and stability characteristics and control law design are realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-29
- Publication Date
- 2026-04-07
AI Technical Summary
Existing technologies cannot effectively calculate the rudder deflection required for a unit normal overload of a statically unstable aircraft after being disturbed, resulting in a lack of necessary inputs for aircraft handling characteristics design and control law design.
By constructing a stability-enhancing control law and establishing an aerodynamic model based on wind tunnel test data, the required rudder deflection for unit normal overload is calculated using small disturbance linearization equations and state-space matrices. Combined with pitch rate and angle of attack feedback gain, the stability and damping characteristics of the aircraft are improved, and the calculations are performed using MATLAB software.
It enables the calculation of the rudder deflection required for a unit normal overload of a statically unstable aircraft at low cost, and provides the necessary inputs for handling and stability characteristics and control law design, ensuring that the aircraft does not diverge under stability augmentation control.
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Figure CN121809074A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of aircraft flight control, and particularly relates to a method and device for calculating the required rudder deflection of a static unstable aircraft per unit normal overload. BACKGROUND
[0002] After a static unstable aircraft is manipulated or disturbed, the normal overload will present a rapid divergence state. The normal overload of an aircraft is an important index for representing the aircraft maneuvering capability, and in the process of aircraft stability design, the required rudder deflection for the normal overload capability is generally taken as a main design index. Therefore, in the process of flight control law design, the required rudder deflection per unit normal overload is taken as the core gain of the control channel to realize accurate static control characteristics.
[0003] The traditional static stable aircraft will not diverge after being manipulated or disturbed, and therefore the calculation of the required rudder deflection per unit normal overload can be realized based on the aircraft aerodynamic data and motion equation. However, for a static unstable aircraft, the traditional calculation method cannot calculate the required rudder deflection per unit normal overload because the aircraft body presents a divergence state.
[0004] Therefore, a method for calculating the required rudder deflection per unit normal overload of a static unstable aircraft is needed, so as to provide necessary design input for aircraft stability design and control law design. SUMMARY
[0005] The purpose of the present application is to provide a method and device for calculating the required rudder deflection per unit normal overload of a static unstable aircraft, so as to solve or alleviate at least one problem in the background art.
[0006] In a first aspect, the technical solution of the present application is: a method for calculating the required rudder deflection per unit normal overload of a static unstable aircraft, comprising:
[0007] selecting a plurality of calculation state points according to the flight envelope, mass characteristics and aircraft type data of the aircraft, establishing an aerodynamic model based on wind tunnel test data, and obtaining a small disturbance linear equation at each calculation state point;
[0008] constructing a stability augmentation control law, the stability augmentation control law changing the aircraft pitch moment characteristics by feeding back the angle of attack and improving the aircraft pitch damping characteristics by feeding back the pitch angular rate, so that the aircraft does not diverge and has desired stability and damping characteristics under the control of the stability augmentation control law;
[0009] establishing a calculation model of the required rudder deflection per unit normal overload based on the stability augmentation control law and the small disturbance linear equation at the calculation state points, the calculation model calculating the normal overload through the pitch angular rate and the angle of attack and the true airspeed, linearizing the calculation model to obtain a state space matrix of the elevator command to the normal overload of the control channel, and obtaining a transfer function of the elevator command to the normal overload of the control channel based on the state space matrix.
[0010] The normal overload value generated by unit elevator deflection is calculated based on the transfer function of the elevator deflection command of the control channel to the normal overload, and the reciprocal of the normal overload value is the required deflection of the unit normal overload.
[0011] Preferably, the angle of attack feedback gain is determined according to the target change of the aircraft pitch moment characteristics.
[0012] Preferably, the pitch rate feedback gain is determined according to the aircraft pitch damping requirement in the relevant standard.
[0013] Preferably, the method for calculating the normal overload based on the pitch rate and the angle of attack and the true airspeed is:
[0014]
[0015] In the formula, Nz is the normal overload, is the true airspeed, is the pitch rate, is the angle of attack derivative, and g is the gravitational acceleration.
[0016] Preferably, when the angle of attack feedback gain and the pitch rate feedback gain in the stability augmentation control law are adjusted due to control requirement changes, the required elevator deflection for unit normal overload needs to be recalculated.
[0017] In another aspect, the application provides a device for calculating the required deflection of a unit normal overload of a statically unstable aircraft, comprising:
[0018] A small perturbation equation module is configured to select a plurality of calculation state points according to the flight envelope, mass characteristics and aircraft type data of the aircraft, establish an aerodynamic model based on wind tunnel test data, and obtain small perturbation linear equations at each calculation state point.
[0019] A stability augmentation control module is configured to construct a stability augmentation control law, which changes the pitch moment characteristics of the aircraft by feeding back the angle of attack and improves the pitch damping characteristics of the aircraft by feeding back the pitch rate, so that the aircraft does not diverge under the control of the stability augmentation control law and has desired stability and damping characteristics.
[0020] A model processing module is configured to establish a calculation model of the required deflection of a unit normal overload based on the stability augmentation control law and the small perturbation linear equations at the calculation state points, the calculation model calculating the normal overload based on the pitch rate and the angle of attack and the true airspeed. The calculation model is linearized to obtain a state space matrix of the elevator deflection command of the control channel to the normal overload, and a transfer function of the elevator deflection command of the control channel to the normal overload is obtained based on the state space matrix.
[0021] The rudder deflection calculation module for unit normal overload is used to calculate the normal overload value generated by unit elevator deflection based on the transfer function from the control channel elevator command to normal overload. The reciprocal of the normal overload value is the rudder deflection required per unit normal overload.
[0022] Preferably, the angle of attack feedback gain is determined based on the target change according to the aircraft pitch moment characteristics.
[0023] Preferably, the pitch rate feedback gain is determined according to the aircraft pitch damping requirements in relevant standards.
[0024] Preferably, the method for calculating normal overload based on pitch rate, angle of attack, and vacuum velocity is as follows:
[0025]
[0026] In the formula, Nz represents the normal overload. Vacuum speed, For pitch rate, Let g be the derivative of the angle of attack, and g be the acceleration due to gravity.
[0027] Preferably, when the control requirements change, adjusting the angle of attack feedback gain and pitch rate feedback gain in the stability enhancement control law requires recalculating the elevator deflection required per unit normal overload.
[0028] Thirdly, this application provides an electronic device, comprising:
[0029] One or more processors;
[0030] Memory;
[0031] One or more applications, which are stored in the memory and configured to be executed by the one or more processors, are configured to implement the method for calculating rudder deflection required for unit normal overload of a statically unstable aircraft as described in any of the preceding claims.
[0032] Finally, this application provides a computer-readable storage medium, characterized in that the computer-readable storage medium stores at least one instruction, at least one program, code set, or instruction set, wherein the at least one instruction, the at least one program, the code set, or instruction set is loaded and executed by a processor to implement the rudder deflection calculation method for unit normal overload of a statically unstable aircraft as described in any of the preceding claims.
[0033] The method for calculating the rudder deflection required for unit normal overload of statically unstable aircraft provided in this application solves the problem that the rudder deflection required for unit normal overload caused by the divergent characteristics of statically unstable aircraft cannot be calculated. It also has low computational cost and can provide necessary design inputs for aircraft handling and stability characteristic design and control law design. Attached Figure Description
[0034] 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.
[0035] Figure 1 This is a schematic diagram illustrating the method for calculating the rudder deflection required for a unit normal overload of a statically unstable aircraft, as described in this application.
[0036] Figure 2 This is a schematic diagram of the stabilization control law architecture of this application.
[0037] Figure 3 This is a schematic diagram of the rudder deflection calculation model required for unit normal overload in this application.
[0038] Figure 4 This is a schematic diagram of the rudder deflection calculation device required for unit normal overload of a statically unstable aircraft according to this application. Detailed Implementation
[0039] 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.
[0040] This application provides a method and apparatus for calculating the rudder deflection required for unit normal overload of a statically unstable aircraft, which solves the problem that the rudder deflection required for unit normal overload cannot be calculated due to the divergent characteristics of statically unstable aircraft. This application only requires a regular computer and MATLAB software to perform the calculation, which has low computational cost and can provide the necessary design input for aircraft handling and stability characteristic design and control law design.
[0041] like Figure 1 As shown, the method for calculating the rudder deflection required for a unit normal overload of a statically unstable aircraft provided in this application includes the following process:
[0042] Step S1: Select multiple calculation state points based on the aircraft's flight envelope, mass characteristics, and aircraft configuration data. Establish an aerodynamic model based on wind tunnel test data and obtain the small perturbation linearization equations at each calculation state point.
[0043] In this application, calculation state points can be selected based on the aircraft's flight envelope, mass characteristics, and aircraft configuration data. An aerodynamic model can be established based on wind tunnel test data, and small disturbance linearization calculations can be performed at each calculation state point to obtain the small disturbance equations at each calculation state point.
[0044] Step S2: Construct a stability augmentation control law. This law changes the aircraft's pitch moment characteristics by feeding back the angle of attack and improves the aircraft's pitch damping characteristics by feeding back the pitch rate.
[0045] like Figure 2 The diagram shows the stability augmentation control law architecture constructed in this application. This law sets feedback angle of attack and feedback pitch rate after the angle of attack and pitch rate output from the small disturbance equation. The feedback angle of attack is fed back into the actuator model through the angle of attack feedback gain KAOA, thereby altering the aircraft's pitch moment characteristics. The feedback pitch rate is fed back into the actuator model through the pitch rate feedback gain KQ, thereby improving the aircraft's pitch damping characteristics. Under the control of the stability augmentation control law, the aircraft will not diverge and will possess the desired stability and damping characteristics.
[0046] In this application, the angle-of-attack feedback gain KAOA can be determined by changing the target based on the aircraft's pitch moment characteristics. Specifically, the angle-of-attack feedback gain KAOA is determined by increasing the target based on the pitch moment coefficient at each calculated state point. The pitch rate feedback gain KQ can be determined according to the aircraft pitch damping requirements in GJB2874.
[0047] In this embodiment of the application, the actuator model may be 20 / (s+20).
[0048] Step S3: Based on the stability augmentation control law in Step S2 and the linearized equation of small disturbance at the calculated state point in Step S1, establish a calculation model for the rudder deflection required for unit normal overload. This calculation model calculates the normal overload using pitch rate, angle of attack, and vacuum speed. Linearize the calculation model to obtain the state space matrix from the elevator command in the control channel to the normal overload. Based on the state space matrix, obtain the transfer function from the elevator command in the control channel to the normal overload.
[0049] like Figure 3 The figure shows the calculation model of the rudder deflection required for unit normal overload established based on the stability augmentation control law and the linearized equation of small disturbance at the calculation state point in this embodiment of the application. The calculation model can be established based on the SIMULINK graphical development platform in MATLAB software. In the figure, the control channel command De_cmd is connected through the Inport input module, and the normal overload Nz is connected through the Outport output module. In the figure, AOA is the angle of attack, Q is the pitch rate, V0 is the vacuum speed, and du / dt represents differentiation. The small disturbance equation is determined according to step S1.
[0050] The computational model established based on the SIMULINK graphical development platform can essentially be processed using MATLAB program statements. Therefore, the computational model can be linearized to obtain the state-space matrix from the control channel elevator command De_cmd to the normal overload Nz. Based on the state-space matrix from the control channel elevator command De_cmd to the normal overload Nz, the transfer function from the control channel elevator command De_cmd to the normal overload Nz can be calculated.
[0051] In this application, the calculation model calculates the normal overload using pitch rate, angle of attack, and vacuum speed. Based on the principles that normal overload equals lift divided by gravity, pitch acceleration, and pitch angle equals angle of attack plus track inclination, the calculation method for normal overload Nz is as follows:
[0052]
[0053] in, For lift, The value represents the lift increment (i.e., the lift increment caused by the angle of attack deviating from the calculated angle of attack), where G is the aircraft's weight, m is the aircraft's mass, and g is the acceleration due to gravity. For pitch acceleration, Vertical velocity, Vacuum speed, For the inclination angle of the flight path, The pitch angle, For the angle of attack, For pitch rate, The value is the derivative of the vertical velocity. The dots above the variables in the equation all represent derivatives. for The derivative of .
[0054] Step S4: Calculate the normal overload value generated per unit elevator deflection based on the transfer function from the elevator command to the normal overload in the control channel. The reciprocal of the normal overload value is the rudder deflection required per unit normal overload.
[0055] In this application, the numerical calculation program for the normal overload generated by the unit elevator deflection can be calculated using the MATLAB program dcgain(G), where G is the transfer function from the control channel elevator command obtained in step S3 to the normal overload.
[0056] In this application, if the angle-of-attack feedback gain KAOA and pitch rate feedback gain KQ in the stability augmentation control law constructed in step S2 are adjusted due to changes in control requirements, then the elevator deflection required per unit normal overload needs to be recalculated using the above method.
[0057] The above process allows us to calculate the control surface deflection required for a unit normal overload of a statically unstable aircraft.
[0058] The method for calculating the rudder deflection required for unit normal overload of statically unstable aircraft provided in this application solves the problem that the rudder deflection required for unit normal overload caused by the divergent characteristics of statically unstable aircraft cannot be calculated. It also has low computational cost and can provide necessary design inputs for aircraft handling and stability characteristic design and control law design.
[0059] like Figure 4 As shown, based on the above technical solution, this application also provides a device for calculating the rudder deflection required for a unit normal overload of a statically unstable aircraft. The device 100 includes:
[0060] The small perturbation equation module 101 is used to select multiple calculation state points based on the aircraft flight envelope, mass characteristics and aircraft configuration data, establish an aerodynamic model based on wind tunnel test data, and obtain the small perturbation linearized equations at each calculation state point.
[0061] The stability augmentation control module 102 is used to construct a stability augmentation control law. The stability augmentation control law changes the pitch moment characteristics of the aircraft by feedback angle of attack and improves the pitch damping characteristics of the aircraft by feedback pitch rate, so that the aircraft does not diverge under the control of the stability augmentation control law and has the desired stability and damping characteristics.
[0062] The model processing module 103 is used to establish a calculation model for the rudder deflection required for unit normal overload based on the stability augmentation control law and the linearized equation of small disturbance at the calculation state point. The calculation model calculates the normal overload by pitch rate, angle of attack and vacuum speed. The calculation model is linearized to obtain the state space matrix from the control channel elevator command to the normal overload. Based on the state space matrix, the transfer function from the control channel elevator command to the normal overload is obtained.
[0063] The rudder deflection calculation module 104 for unit normal overload is used to calculate the normal overload value generated by unit elevator deflection based on the transfer function from the elevator command in the control channel to the normal overload. The reciprocal of the normal overload value is the rudder deflection required per unit normal overload.
[0064] The processing procedures of each module of the rudder deflection calculation device for unit normal overload of statically unstable aircraft in this application can refer to the above-mentioned rudder deflection calculation method for unit normal overload of statically unstable aircraft, and will not be repeated here.
[0065] In addition, this application also provides an electronic device, which includes:
[0066] One or more processors;
[0067] Memory;
[0068] One or more applications, which are stored in the memory and configured to be executed by the one or more processors, are configured to implement the method for calculating rudder deflection required for unit normal overload of a statically unstable aircraft as described in any of the preceding claims.
[0069] Finally, this application also provides a computer-readable storage medium, characterized in that the computer-readable storage medium stores at least one instruction, at least one program, code set, or instruction set, wherein the at least one instruction, the at least one program, the code set, or the instruction set is loaded and executed by a processor to implement the rudder deflection calculation method for unit normal overload of statically unstable aircraft as described above.
[0070] 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.
Claims
1. A method for calculating the rudder deflection required for a unit normal overload of a statically unstable aircraft, characterized in that, include: Multiple calculation state points are selected based on the aircraft flight envelope, mass characteristics and aircraft configuration data. An aerodynamic model is established based on wind tunnel test data, and the small perturbation linearization equations at each calculation state point are obtained. A stability augmentation control law is constructed, which changes the aircraft pitch moment characteristics by feedback angle of attack and improves the aircraft pitch damping characteristics by feedback pitch rate, so that the aircraft does not diverge under the control of the stability augmentation control law and has the desired stability and damping characteristics. Based on the stability enhancement control law and the linearized equation of small disturbance at the calculated state point, a calculation model for the rudder deflection required for unit normal overload is established. This calculation model calculates the normal overload by pitch rate, angle of attack and vacuum speed. The calculation model is linearized to obtain the state space matrix from the control channel elevator command to the normal overload. Based on the state space matrix, the transfer function from the control channel elevator command to the normal overload is obtained. The normal overload value generated per unit elevator deflection is calculated based on the transfer function from the control channel elevator command to the normal overload. The reciprocal of the normal overload value is the rudder deflection required per unit normal overload.
2. The method for calculating the rudder deflection required for a unit normal overload of a statically unstable aircraft as described in claim 1, characterized in that, The angle-of-attack feedback gain is determined based on the target change according to the aircraft pitch moment characteristics.
3. The method for calculating the rudder deflection required for a unit normal overload of a statically unstable aircraft as described in claim 1, characterized in that, The pitch rate feedback gain is determined according to the aircraft pitch damping requirements in relevant standards.
4. The method for calculating the rudder deflection required for a unit normal overload of a statically unstable aircraft as described in any one of claims 1 to 3, characterized in that, The method for calculating normal overload based on pitch rate, angle of attack, and vacuum velocity is as follows: In the formula, Nz represents the normal overload. Vacuum speed, For pitch rate, Let g be the derivative of the angle of attack, and g be the acceleration due to gravity.
5. The method for calculating the rudder deflection required for a unit normal overload of a statically unstable aircraft as described in claim 4, characterized in that, When control requirements change, adjusting the angle-of-attack feedback gain and pitch rate feedback gain in the stability augmentation control law requires recalculating the elevator deflection required per unit normal overload.
6. A device for calculating rudder deflection required for a unit normal overload of a statically unstable aircraft, characterized in that, include: The small perturbation equation module is used to select multiple calculation state points based on the aircraft's flight envelope, mass characteristics, and flight configuration data, establish an aerodynamic model based on wind tunnel test data, and obtain the small perturbation linearized equations at each calculation state point. The stability augmentation control module is used to construct a stability augmentation control law. The stability augmentation control law changes the aircraft pitch moment characteristics by feedback angle of attack and improves the aircraft pitch damping characteristics by feedback pitch rate, so that the aircraft does not diverge under the control of the stability augmentation control law and has the desired stability and damping characteristics. The model processing module is used to establish a calculation model of the rudder deflection required for unit normal overload based on the stability enhancement control law and the linearized equation of small disturbance at the calculation state point. The calculation model calculates the normal overload by pitch rate, angle of attack and vacuum speed. The calculation model is linearized to obtain the state space matrix from the control channel elevator command to the normal overload. Based on the state space matrix, the transfer function from the control channel elevator command to the normal overload is obtained. The rudder deflection calculation module for unit normal overload is used to calculate the normal overload value generated by unit elevator deflection based on the transfer function from the control channel elevator command to normal overload. The reciprocal of the normal overload value is the rudder deflection required per unit normal overload.
7. The rudder deflection calculation device for a unit normal overload of a statically unstable aircraft as described in claim 6, characterized in that, The angle-of-attack feedback gain is determined based on the target change according to the aircraft pitch moment characteristics.
8. The rudder deflection calculation device for a unit normal overload of a statically unstable aircraft as described in claim 7, characterized in that, The pitch rate feedback gain is determined according to the aircraft pitch damping requirements in relevant standards.
9. The rudder deflection calculation device for a unit normal overload of a statically unstable aircraft as described in any one of claims 6 to 8, characterized in that, The method for calculating normal overload based on pitch rate, angle of attack, and vacuum velocity is as follows: In the formula, Nz represents the normal overload. Vacuum speed, For pitch rate, Let g be the derivative of the angle of attack, and g be the acceleration due to gravity.
10. The rudder deflection calculation device for a unit normal overload of a statically unstable aircraft as described in claim 9, characterized in that, When control requirements change, adjusting the angle-of-attack feedback gain and pitch rate feedback gain in the stability augmentation control law requires recalculating the elevator deflection required per unit normal overload.
11. An electronic device, characterized in that, include: One or more processors; Memory; One or more applications, which are stored in the memory and configured to be executed by the one or more processors, are configured to implement the method for calculating rudder deflection required for unit normal overload of a statically unstable aircraft as described in any one of claims 1 to 5.
12. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores at least one instruction, at least one program, code set, or instruction set, wherein the at least one instruction, the at least one program, the code set, or instruction set is loaded and executed by a processor to implement the rudder deflection calculation method for unit normal overload of a statically unstable aircraft as described in any one of claims 1 to 5.