Fixed horizontal tail type fly-by-wire aircraft leveling control law design method

Abstract

The invention provides a fixed horizontal tail type fly-by-wire aircraft leveling control law design method, which comprises the following steps of: when an aircraft meets a condition of entering a leveling control law, recording a flight control law integral channel instruction ELNMINT at a triggering moment; generating an elevator control command component ELFLAREFWD through a forward command shaping module based on the joystick displacement signal; the method comprises the following steps: introducing an integral channel instruction ELNMINT into a leveling control law, and obtaining a bias instruction component ELFLAREOFFSET under the leveling control law after the integral channel instruction ELNMINT passes through an instruction amplitude limiting module; subtracting the bias instruction ELFLAREOFFSET from the integral channel instruction ELNMINT to obtain an instruction initial value ELFLAREFADER0 which needs to be faded during instruction transition; after the instruction initial value ELFLAREFADER 0 passes through a desalting device module, a real-time control surface control instruction component ELFLAREFADER is formed; and an elevator control instruction ELCMD under the leveling control law is obtained. According to the method, the switching transient state can be reduced by introducing the flight control law integral channel instruction component into the leveling control law, and the method has remarkable advantages in the aspects of improving the flight safety, optimizing the flight quality, enhancing the system flexibility, improving the automation level and the like.

Description

Technical Field

[0001] The invention relates to the technical field of fly-by-wire flight control law, and in particular to a method for designing a flare control law for a fixed horizontal tail type fly-by-wire aircraft. Background Art

[0002] Traditional mechanically controlled aircraft have speed static stability, that is, to obtain and maintain a speed lower than the trim speed, a pulling force must be used; to obtain and maintain a speed higher than the trim speed, a thrust force must be used.

[0003] During the landing and leveling phase of the aircraft, the pilot needs to continue to decelerate with the stick to obtain the touchdown attitude and finally complete the landing process. For fly-by-wire aircraft with a neutral speed stability control law configuration, the pilot no longer needs to use a pulling force to maintain a speed lower than the trim speed. During the landing and leveling phase, the pilot pulls the stick to decelerate and releases the stick in time to maintain the attitude. This design feature is different from the traditional mechanical control system aircraft, which brings additional flight burden to the pilot during landing and touchdown. In order to give the aircraft a regular leveling feeling during the landing and leveling phase, the same type of aircraft (A320, A350, etc.) are designed with a separate leveling control law for transition before landing and touchdown to destroy the neutral speed stability and restore the static stability of the aircraft. The same type of aircraft all have a movable horizontal tail. When entering the leveling control law, the movable horizontal tail is first frozen, and then the control law is switched to the control law configuration of the stick displacement command elevator. The movable horizontal tail is generally used to unload the elevator during automatic trimming, and the frozen horizontal tail can transfer the trim amount of the aircraft during level flight to the leveling control law, thereby achieving a smooth transition when the aircraft control law mode is switched. For fixed-tail fly-by-wire aircraft, the automatic trim function is entirely generated by the elevator. If no processing is performed when entering the leveling control law, it will result in a large transient response. Summary of the invention

[0004] In order to solve the problems existing in the traditional fly-by-wire flare control law, the purpose of the present invention is to provide a method for designing the flare control law for a fixed horizontal tail fly-by-wire aircraft. The method can reduce the switching transient by referencing the flight control law integral channel command component into the flare control law, and has significant advantages in improving flight safety, optimizing flight quality, enhancing system flexibility and improving the level of automation.

[0005] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0006] A method for designing a flare control law for a fixed horizontal tail fly-by-wire aircraft, the method comprising the following steps:

[0007] When the aircraft meets the conditions for entering the leveling control law, the flight control law integral channel instruction ELE_NM_INT at the triggering moment is recorded;

[0008] Generate an elevator control command component ELE_FLARE_FWD based on the joystick displacement signal through a forward command shaping module;

[0009] The integral channel instruction ELE_NM_INT is introduced into the leveling control law, and the bias instruction component ELE_FLARE_OFFSET under the leveling control law is obtained after passing through the instruction limit module;

[0010] Subtract the offset instruction ELE_FLARE_OFFSET from the integral channel instruction ELE_NM_INT to obtain the instruction initial value ELE_FLARE_FADER0 that needs to be faded during instruction transition;

[0011] After the command initial value ELE_FLARE_FADER0 passes through a fader module, a real-time rudder control command component ELE_FLARE_FADER is formed;

[0012] The elevator control command ELE_CMD under the leveling control law is obtained based on the elevator control command component ELE_FLARE_FWD, the offset command component ELE_FLARE_OFFSET and the control surface control command component ELE_FLARE_FADER.

[0013] According to a method for designing a flare control law for a fixed horizontal tail type fly-by-wire aircraft provided by the present invention, the step of generating an elevator control command component ELE_FLARE_FWD comprises:

[0014] The forward control logic based on the leveling control law adopts the control law configuration of the elevator with stick displacement command to make the aircraft have speed static stability;

[0015] The generated joystick displacement signal is passed through the forward command shaping module to generate the elevator control command component ELE_FLARE_FWD, which is expressed as the following formula:

[0016] ELE_FLARE_FWD=KP*DE

[0017] Among them, the forward instruction shaping module is the forward transmission ratio of the aircraft, and DE is the control stick displacement signal.

[0018] According to a method for designing a flare control law for a fixed horizontal tail fly-by-wire aircraft provided by the present invention, a forward transmission ratio gain of a forward instruction shaping module is 0.2.

[0019] According to a method for designing a flare control law for a fixed horizontal tail type fly-by-wire aircraft provided by the present invention, an integral channel instruction ELE_NM_INT is introduced into the flare control law, which is equivalent to the effect of freezing the horizontal tail of similar aircraft and reduces the transient state during instruction transition; when the aircraft determines that the conditions for entering the flare control law are met (radio altitude is less than 15m), the flight control law integral channel instruction ELE_NM_INT at the triggering moment is recorded, which is expressed as the following formula:

[0020] ELE_NM_INT=KI*(errori+error*ts)

[0021] Among them, KI is the integral channel control gain, KI=3; errori is the error between the expected value and the actual value at the moment before the trigger point; error is the error between the expected value and the actual value at the trigger moment; ts is the sampling step.

[0022] According to a method for designing a flare control law for a fixed horizontal tail type fly-by-wire aircraft provided by the present invention, in the case of a non-command deviation in the integrator, a command limiter module is used to ensure that the command of the integral channel does not exceed the range that the aircraft control system can handle;

[0023] When the integral channel instruction causes the offset instruction component ELE_FLARE_OFFSET to stop at the most unfavorable position due to non-instructional reasons, the amplitude of the relevant instruction will be limited by the instruction limit module, which is expressed as the following formula:

[0024]

[0025] According to a method for designing a flare control law for a fixed horizontal tail fly-by-wire aircraft provided by the present invention, the command limiter module adopts a limiter range of -5 degrees to 5 degrees, that is, LIM_UP = 5 degrees, LIM_DN = -5 degrees.

[0026] According to a method for designing a flare control law for a fixed horizontal tail fly-by-wire aircraft provided by the present invention, the initial value of the instruction ELE_FLARE_FADER0 passes through a fader module to form a real-time control surface control instruction component ELE_FLARE_FADER; starting from the moment of entering the flare control law, the initial value of the instruction ELE_FLARE_FADER0 is gradually faded to zero within a specified time to reduce the transient state caused by the aircraft mode switching; the fader module adopts linear fade logic, and the fade time ΔT=5 seconds, which is expressed as the following formula:

[0027] ELE_FLARE_FADER=ELE_FLARE_FADER0*f(t)

[0028] Among them, the function f(t) is a fade function, which uses linear fade logic. The specific formula is as follows:

[0029]

[0030] Here, t is the real time starting from the triggering moment t=0 to enter the leveling state.

[0031] According to a method for designing a flare control law for a fixed horizontal tail type fly-by-wire aircraft provided by the present invention, the elevator control command of the flare control law is the following formula:

[0032] ELE_CMD=ELE_FLARE_FWD+ELE_FLARE_OFFSET+ELE_FLARE_FADER

[0033] Among them, ELE_FLARE_FWD is the forward control channel instruction; ELE_FLARE_OFFSET is the rudder offset instruction; ELE_FLARE_FADER is the real-time instruction generated by the instruction transition link.

[0034] It can be seen that the present invention has the following beneficial effects:

[0035] 1. The present invention ensures accurate control of the aircraft attitude during the leveling phase by accurately recording the flight control law integral channel command at the triggering moment and generating control commands based on the joystick displacement signal, thereby reducing flight safety hazards caused by inaccurate control.

[0036] 2. The present invention introduces an instruction limiter module and a desalter module to limit and desalinate the control instructions, thereby preventing sudden changes in the control instructions, making the aircraft's attitude adjustment more stable and improving flight stability and safety.

[0037] 3. The present invention realizes the smooth transition of control instructions by calculating the initial value of the instruction that needs to be faded during instruction transition and processing it through the fader module, thereby avoiding the jitter or instability of the aircraft caused by sudden changes in control instructions during the leveling stage, thereby improving the flight quality.

[0038] 4. The elevator control command ELE_CMD finally obtained by the present invention is the result of integrating the forward command, the offset command and the control surface control command components, making the control of the aircraft more comprehensive and accurate, and further improving the flight quality.

[0039] 5. This method adopts a modular design concept, including a forward command shaping module, a command limiter module and a desalination module. This design makes the system easy to maintain and upgrade, and each module can be adjusted and optimized according to different flight requirements.

[0040] 6. By adjusting the control parameters and strategies of each module, this method can adapt to different types of fixed-horizontal-tail fly-by-wire aircraft as well as different flight environments and mission requirements, and has strong adaptability and flexibility.

[0041] 7. The present invention realizes the whole process of automatic control from the triggering moment to the generation of elevator control instructions, reduces the need for manual intervention, and improves the level of flight automation. Automatic control reduces the pilot's operating burden and psychological pressure, allowing the pilot to focus more on the execution of the flight mission and the monitoring of the flight status.

[0042] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 The present invention is a flow chart of an embodiment of a method for designing a leveling control law for a fixed horizontal tail type fly-by-wire aircraft.

[0044] Figure 2 The present invention is a logic principle diagram of a flight control law in an embodiment of a method for designing a leveling control law for a fixed horizontal tail type fly-by-wire aircraft.

[0045] Figure 3 The present invention is a logic principle diagram of a flare control law in an embodiment of a method for designing a flare control law for a fixed horizontal tail type fly-by-wire aircraft.

[0046] Figure 4 It is a time domain curve diagram of a test flight result of an aircraft landing flare process in an embodiment of a method for designing a flare control law for a fixed horizontal tail type fly-by-wire aircraft of the present invention. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0049] Flare control law: The flare control law is the control law used by the flight control system and thrust control system during the flare phase of automatic landing. It ensures the stability and safety of the aircraft before landing.

[0050] Flight control law: The flight control law is the algorithm for the flight control system to generate control commands, which describes the functional relationship between the controlled state variables and the system input signals. During the leveling phase, this algorithm will calculate and output the corresponding control commands based on the actual state of the aircraft (such as speed, altitude, attitude, etc.) and the pilot's input (or the command of the autopilot).

[0051] The present invention is a control law design that can be applied to a fixed-horizontal-tail fly-by-wire aircraft to obtain a conventional flare feeling during the landing flare phase. The invention has a simple structure and can be extended to all fixed-horizontal-tail fly-by-wire transport aircraft with neutral speed stability for application.

[0052] See also Figures 1 to 4 The present invention provides a method for designing a flare control law for a fixed horizontal tail type fly-by-wire aircraft, the method comprising the following steps:

[0053] Step S1, when the aircraft meets the conditions for entering the leveling control law, the flight control law integral channel instruction ELE_NM_INT at the triggering moment is recorded;

[0054] Step S2, generating an elevator control command component ELE_FLARE_FWD through a forward command shaping module based on the joystick displacement signal;

[0055] Step S3, introducing the integral channel instruction ELE_NM_INT into the leveling control law, which is equivalent to the effect of freezing the horizontal tail of similar aircraft, and reduces the transient state during instruction transition. The integral channel instruction ELE_NM_INT passes through the instruction limit module to obtain the offset instruction component ELE_FLARE_OFFSET under the leveling control law;

[0056] Step S4, subtracting the offset instruction ELE_FLARE_OFFSET from the integral channel instruction ELE_NM_INT to obtain the instruction initial value ELE_FLARE_FADER0 that needs to be faded during instruction transition;

[0057] Step S5, the command initial value ELE_FLARE_FADER0 passes through a fader module to form a real-time control surface control command component ELE_FLARE_FADER;

[0058] Step S6, obtaining the elevator control instruction ELE_CMD under the flare control law based on the elevator control instruction component ELE_FLARE_FWD, the offset instruction component ELE_FLARE_OFFSET, and the control surface control instruction component ELE_FLARE_FADER.

[0059] In the above step S1, when the aircraft meets the conditions for entering the leveling control law, recording the ELE_NM_INT command value at the triggering time generally involves the following steps:

[0060] Monitoring flight status: The flight control system will continuously monitor the actual status of the aircraft, including speed, altitude, attitude, etc.

[0061] Determine entry conditions: When the aircraft's state meets the preset conditions for entering the leveling control law (such as reaching a specific altitude, speed or attitude range), the flight control system will make a judgment.

[0062] Calculate control instructions: Once the leveling control law is entered, the flight control system will calculate the control instructions based on the current flight status and the preset control law algorithm.

[0063] Record instruction value: In this process, ELE_NM_INT is one of the control instructions of the integral channel, and its value will be calculated and recorded in real time.

[0064] In the above step S2, the elevator control command component ELE_FLARE_FWD is generated, including:

[0065] Based on the forward control logic of the leveling control law, the control law configuration of the elevator with the stick displacement command is adopted to make the aircraft have speed static stability, which is expressed as the following formula:

[0066] ELE_FLARE_FWD=KP*DE

[0067] Among them, DE is the steering column displacement signal;

[0068] The generated joystick displacement signal is passed through the forward command shaping module to generate the elevator control command component ELE_FLARE_FWD;

[0069] Among them, the forward instruction shaping module is the forward transmission ratio of the aircraft, which is related to the design characteristics and design intent of the aircraft.

[0070] In this embodiment, the forward transmission ratio gain of the forward instruction shaping module is 0.2.

[0071] Specifically, in the aircraft control system, the forward command shaping module is responsible for receiving commands from the pilot or other control sources, and preprocessing, adjusting or shaping these commands to ensure that they are suitable for being received and executed by the aircraft's actuators. The forward transmission ratio can be regarded as the gain or attenuation ratio of the forward command shaping module to the input command, which determines the degree of amplification or reduction of the command during the transmission process.

[0072] If the forward transmission ratio gain is greater than 1, the input command will be amplified. Gain equal to 1: In this case, the input command remains unchanged, that is, the forward command shaping module does not perform any amplification or reduction on the command. Gain less than 1 (such as 0.2): When the gain is 0.2, the input command will be significantly reduced, which helps to limit the output range, enhance system stability, and may reduce the impact of external interference on the system.

[0073] In this embodiment, the fly-by-wire aircraft with automatic longitudinal trim usually adopts a proportional-integral control law configuration. Among them, the proportional channel is used to track the deviation of the desired instruction, and when there is a deviation, it is corrected in real time; and the integral channel is used to eliminate the steady-state error of the control system, which is equivalent to the trim component of the aircraft during level flight. The integral channel instruction ELE_NM_INT is introduced into the leveling control law, which is equivalent to the effect of freezing the horizontal tail of similar aircraft and reducing the transient state during instruction transition. When the aircraft determines that the conditions for entering the leveling control law are met (radio altitude is less than 15m), the flight control law integral channel instruction ELE_NM_INT at the triggering moment is recorded, which is expressed as the following formula:

[0074] ELE_NM_INT=KI*(errori+error*ts)

[0075] Among them, KI is the integral channel control gain, and in this patent KI=3; errori is the error between the expected value and the actual value at the moment before the trigger point; error is the error between the expected value and the actual value at the trigger moment; ts is the sampling step.

[0076] In the above step S3, the limit value of the command limit module is limited by the control efficiency of the aircraft. It is used to ensure that the aircraft still has an acceptable landing leveling capability when the integral channel command is in an abnormal position due to non-commands in the integrator and the offset command component ELE_FLARE_OFFSET stops at the most unfavorable position.

[0077] In this embodiment, in the case of non-command deviation in the integrator, the command limit module is used to ensure that the integral channel command does not exceed the range that the aircraft control system can handle;

[0078] When the integral channel instruction causes the offset instruction component ELE_FLARE_OFFSET to stop at the most unfavorable position due to non-instructional reasons, the amplitude of the relevant instruction will be limited by the instruction limiting module.

[0079] In this embodiment, the instruction limiting module adopts a limiting range of -5 degrees to 5 degrees.

[0080] Specifically, the integral channel instruction ELE_NM_INT passes through the instruction limit module to obtain the bias instruction component ELE_FLARE_OFFSET under the leveling control law; the limit value of the instruction limit module is limited by the aircraft's control efficiency. It is used when the integral channel instruction is in an abnormal position due to non-instructions in the integrator and the bias instruction component ELE_FLARE_OFFSET stops at the most unfavorable position. The aircraft can still have an acceptable landing leveling capability, which is expressed as the following formula:

[0081]

[0082] In this embodiment, the instruction limit module adopts a limit range of -5 degrees to 5 degrees, that is, LIM_UP=5 degrees, LIM_DN=-5 degrees.

[0083] In the above step S4, the offset instruction ELE_FLARE_OFFSET is subtracted from the integral channel instruction ELE_NM_INT to obtain the instruction initial value ELE_FLARE_FADER0 that needs to be faded during instruction transition. The calculation formula is as follows:

[0084]

[0085] In this embodiment, the initial value of the command ELE_FLARE_FADER0 passes through a fader module to form a real-time control surface control command component ELE_FLARE_FADER; starting from the moment of entering the leveling control law, the initial value of the command ELE_FLARE_FADER0 is gradually faded to zero within a specified time to reduce the transient state caused by the aircraft mode switching. In this embodiment, the fader module adopts linear fade logic, and the fade time ΔT=5 seconds.

[0086] ELE_FLARE_FADER=ELE_FLARE_FADER0*f(t)

[0087] Among them, function f(t) is the fade function. This patent adopts linear fade logic. The specific formula is as follows:

[0088]

[0089] Here, t is the real time starting from the triggering moment t=0 to enter the leveling state.

[0090] In this embodiment, the transition time design of the desalination module is limited by the transient response size of the aircraft.

[0091] In this embodiment, the fader module adopts a 5-second linear fade logic. In the fader module adopting the 5-second linear fade logic, the command initial value ELE_FLARE_FADER0 will gradually fade to zero within 5 seconds, that is, in each time step, the value of the command initial value ELE_FLARE_FADER will decrease according to a fixed ratio until it finally becomes zero. It can be seen that the fader module adopting the 5-second linear fade logic in this embodiment is a simple and effective control strategy for reducing transient response when switching the aircraft control mode.

[0092] In this embodiment, the flight control law of the fly-by-wire aircraft generally adopts the design feature of neutral speed stability, which is different from the control habits of traditional aircraft. In order to ensure that the aircraft can simulate the control habits of traditional aircraft before landing, civil aircraft usually design a leveling control law for transition. The significant design feature of the leveling control law is to restore the static speed stability, and different aircraft have different ways of achieving it. Since the aircraft is a fixed horizontal tail fly-by-wire aircraft, it is different from the general civil movable horizontal tail aircraft, so the design of the leveling control law will be different. Therefore, the elevator control instruction ELE_CMD of the leveling control law of this embodiment is the following formula:

[0093] ELE_CMD=ELE_FLARE_FWD+ELE_FLARE_OFFSET+ELE_FLARE_FADER

[0094] Among them, ELE_FLARE_FWD is the forward control channel instruction; ELE_FLARE_OFFSET is the rudder offset instruction; ELE_FLARE_FADER is the real-time instruction generated by the instruction transition link.

[0095] like Figure 4 As shown, Figure 4 This is a time domain curve of the aircraft landing process using the method of this embodiment, which shows that the method is simple, reliable and effective.

[0096] In summary, the present invention ensures accurate control of the aircraft attitude during the leveling phase by accurately recording the flight control law integral channel instructions at the triggering moment and generating control instructions based on the joystick displacement signal, thereby reducing flight safety hazards caused by inaccurate control.

[0097] Furthermore, the present invention introduces an instruction limiting module and a desalination module to limit and desalinate the control instructions, thereby preventing sudden changes in the control instructions, making the aircraft's attitude adjustment more stable and improving flight stability and safety.

[0098] Furthermore, the present invention realizes a smooth transition of control instructions by calculating the initial value of the instructions that need to be faded during instruction transition and processing it through a fader module, thereby avoiding jitter or instability caused by sudden changes in control instructions during the leveling phase of the aircraft, thereby improving the flight quality.

[0099] Furthermore, the elevator control command ELE_CMD finally obtained by the present invention is the result of integrating the forward command, the offset command and the control surface control command components, so that the control of the aircraft is more comprehensive and accurate, and the flight quality is further improved.

[0100] Furthermore, the method adopts a modular design concept, including a forward command shaping module, a command limiting module and a desalinator module. This design makes the system easy to maintain and upgrade, and each module can be adjusted and optimized according to different flight requirements.

[0101] Furthermore, by adjusting the control parameters and strategies of each module, the method of the present invention can adapt to different types of fixed horizontal tail fly-by-wire aircraft and different flight environments and mission requirements, and has strong adaptability and flexibility.

[0102] Furthermore, the present invention realizes full-process automated control from the triggering moment to the generation of elevator control instructions, reduces the need for manual intervention, and improves the level of flight automation.

[0103] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0104] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A method for designing a flare control law for a fixed horizontal tail fly-by-wire aircraft, characterized in that: The method comprises the following steps: Generate an elevator control command component ELE_FLARE_FWD based on the joystick displacement signal through a forward command shaping module; When the aircraft meets the conditions for entering the leveling control law, the flight control law integral channel instruction ELE_NM_INT at the triggering moment is recorded; The integral channel instruction ELE_NM_INT is introduced into the leveling control law, and the bias instruction component ELE_FLARE_OFFSET under the leveling control law is obtained after passing through the instruction limit module; Subtract the offset instruction ELE_FLARE_OFFSET from the integral channel instruction ELE_NM_INT to obtain the instruction initial value ELE_FLARE_FADER0 that needs to be faded during instruction transition; After the command initial value ELE_FLARE_FADER0 passes through a fader module, a real-time rudder control command component ELE_FLARE_FADER is formed; The elevator control command ELE_CMD under the leveling control law is obtained based on the elevator control command component ELE_FLARE_FWD, the offset command component ELE_FLARE_OFFSET and the control surface control command component ELE_FLARE_FADER.

2. The method according to claim 1, characterized in that The generating of the elevator control command component ELE_FLARE_FWD comprises: The forward control logic based on the leveling control law adopts the control law configuration of the elevator with stick displacement command to make the aircraft have speed static stability; The generated joystick displacement signal is passed through the forward command shaping module to generate the elevator control command component ELE_FLARE_FWD, which is expressed as the following formula: ELE_FLARE_FWD=KP*DE Among them, the forward instruction shaping module is the forward transmission ratio of the aircraft, and DE is the control stick displacement signal.

3. The method according to claim 2, characterized in that: The forward transmission ratio gain of the forward command shaping module is 0.

2.

4. The method according to claim 1, characterized in that: The integral channel instruction ELE_NM_INT is introduced into the leveling control law, which is equivalent to the effect of freezing the horizontal tail of similar aircraft, reducing the transient state during instruction transition; when the aircraft determines that the conditions for entering the leveling control law are met, the flight control law integral channel instruction ELE_NM_INT at the triggering moment is recorded, which is expressed as the following formula: ELE_NM_INT=KI*(errori+error*ts) Among them, KI is the integral channel control gain, KI=3; errori is the error between the expected value and the actual value at the moment before the trigger point; error is the error between the expected value and the actual value at the trigger moment; ts is the sampling step.

5. The method according to claim 1, characterized in that: In the event of non-command deviations in the integrator, the command limiter module is used to ensure that the command of the integral channel does not exceed the range that the aircraft control system can handle; When the integral channel instruction causes the offset instruction component ELE_FLARE_OFFSET to stop at the most unfavorable position due to non-instructional reasons, the amplitude of the relevant instruction will be limited by the instruction limit module, which is expressed as the following formula:

6. The method according to claim 5, characterized in that: The command limit module adopts a limit range of -5 degrees to 5 degrees, that is, LIM_UP = 5 degrees, LIM_DN = -5 degrees.

7. The method according to any one of claims 1 to 6, characterized in that: After the initial value of the command ELE_FLARE_FADER0 passes through a fader module, a real-time control surface command component ELE_FLARE_FADER is formed; starting from the moment of entering the leveling control law, the initial value of the command ELE_FLARE_FADER0 is gradually faded to zero within the specified time to reduce the transient state caused by the aircraft mode switching; the fader module adopts linear fade logic, and the fade time ΔT = 5 seconds, which is expressed as the following formula: ELE_FLARE_FADER=ELE_FLARE_FADER0*f(t) Among them, the function f(t) is a fade function, which uses linear fade logic. The specific formula is as follows: Here, t is the real time starting from the triggering moment t=0 to enter the leveling state.

8. The method according to any one of claims 1 to 6, characterized in that: The elevator control command of the flare control law is as follows: ELE_CMD=ELE_FLARE_FWD+ELE_FLARE_OFFSET+ELE_FLARE_FADER Among them, ELE_FLARE_FWD is the forward control channel instruction; ELE_FLARE_OFFSET is the rudder offset instruction; ELE_FLARE_FADER is the real-time instruction generated by the instruction transition link.

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