A method and system for flight control

Abstract

The application discloses a flight control method and system. The method can comprise: acquiring measurement signals of an air data system, an inertial navigation system and a flight control system; calculating a center of gravity of an aircraft based on the measurement signals; mapping the center of gravity of the aircraft to a fuzzy center of gravity signal corresponding to a center of gravity interval according to a preset center of gravity partition; and generating a control surface gain based on the fuzzy center of gravity signal, wherein the fuzzy center of gravity signals of different center of gravity intervals correspond to different control surface gains. Through the embodiment of the application, the flight control parameters can be adjusted according to the center of gravity, and the flight quality of the aircraft is improved.

Description

Technical Field

[0001] This application relates to the field of aircraft, and in particular to a method and system for flight control. Background Technology

[0002] In traditional flight control systems, the center of gravity is primarily determined by ground loading or manual input, and flight control laws are typically designed based on a fixed center of gravity position. During flight, dynamic changes in the center of gravity due to fuel consumption, passenger movement, and other factors can cause the aircraft's handling characteristics to deviate from design expectations, affecting the pilot's control feel. Summary of the Invention

[0003] This application content is provided to introduce, in a simplified form, some concepts that will be further described in the following detailed description. This application content is not intended to identify key or essential features of the claimed subject matter, nor is it intended to help determine the scope of the claimed subject matter.

[0004] This application aims to provide a method and system for flight control.

[0005] In a first aspect, embodiments of this application provide a flight control method, which may include: acquiring measurement signals from an atmospheric data system, an inertial navigation system, and a flight control system; calculating the aircraft's center of gravity based on the measurement signals; mapping the aircraft's center of gravity to a fuzzy center of gravity signal corresponding to a center of gravity interval according to a preset center of gravity partition; and generating control surface gains based on the fuzzy center of gravity signals, wherein the fuzzy center of gravity signals of different center of gravity intervals correspond to different control surface gains. The flight control method provided by this application comprehensively utilizes multi-source measurement signals from an atmospheric data system, an inertial navigation system, and a flight control system for real-time center of gravity calculation, eliminating errors caused by traditional reliance on ground loading or manual input, resulting in highly reliable center of gravity estimation results. This application maps continuous center of gravity values ​​to a finite number (e.g., forward, middle, and aft) fuzzy center of gravity signals through preset center of gravity partitions, and calls different control surface gains based on these discrete signals, significantly simplifying the mathematical model and software architecture of the control law compared to continuous interpolation parameter tuning methods. Furthermore, when the center of gravity signal contains noise or instantaneous changes, the fuzzy partitioning strategy does not cause frequent fluctuations in control surface gains, effectively avoiding the deterioration in handling quality that may result from continuous parameter tuning.

[0006] In one optional implementation, the fuzzy center-of-gravity signal includes a forward center-of-gravity signal, a middle center-of-gravity signal, and a rear center-of-gravity signal. Mapping the aircraft's center of gravity to a fuzzy center-of-gravity signal corresponding to a predetermined center-of-gravity partition includes: converting aircraft center-of-gravity values ​​greater than or equal to Xcg1 and less than Xcg2 into forward center-of-gravity signals; converting aircraft center-of-gravity values ​​greater than or equal to Xcg2 and less than Xcg3 into middle center-of-gravity signals; or converting aircraft center-of-gravity values ​​greater than or equal to Xcg3 and less than or equal to Xcg4 into rear center-of-gravity signals. Partitioning based on fuzzy signals transforms the complex continuous nonlinear control problem into a linear control problem at several typical operating points. This not only reduces the real-time computational burden on the onboard computer but also significantly reduces the design complexity of the flight control law and the cost of airworthiness verification. For the rear center-of-gravity state, the system automatically switches to an appropriate low-gain parameter to prevent over-control and excessively light stick force, ensuring a consistent control feel across the entire center-of-gravity range, thereby allowing the operational center of gravity to extend rearward.

[0007] In one optional implementation, the measured signals include aileron deflection and engine thrust. During takeoff, the aileron deflection and engine thrust both correct the aircraft's center of gravity forward. Introducing aileron deflection as a correction parameter for the lift coefficient and the influence of engine thrust on the pitch moment into the aerodynamic model enables accurate calculation of the center of gravity across the entire flight envelope, including takeoff, go-around, and aileron-assisted lift configurations, significantly improving the accuracy of center of gravity estimation.

[0008] In an optional embodiment, the method further includes: limiting the rate of change of the aircraft's center of gravity to meet a preset threshold; and filtering the aircraft's center of gravity. By limiting the rate of change of the estimated real-time center of gravity signal, the dynamic change process of the center of gravity signal conforms to the objective laws of actual physical load changes in the aircraft (such as fuel consumption rate, passenger movement speed, etc.), effectively avoiding sudden changes in the center of gravity signal caused by sensor transient noise, atmospheric disturbances, or transient errors in the calculation model. Low-pass filtering of the center of gravity signal can effectively filter out high-frequency noise components mixed in with the center of gravity signal.

[0009] In an optional implementation, the method further includes: performing a latching operation on the aircraft's center of gravity in response to the aircraft's current flight mode and / or overload value. Through the latching operation, the system can forcibly maintain the last valid center of gravity value before the maneuver or special mode occurs during special phases, thereby avoiding control law mis-adjustment due to center of gravity estimation distortion and ensuring that the flight control system performs control surface gain scheduling with a stable center of gravity reference value.

[0010] In one optional implementation, the latching operation on the aircraft's center of gravity in response to the aircraft's current flight mode and / or overload value includes: latching the aircraft's center of gravity in response to an overload greater than 1.3g or less than 0.8g, or latching the aircraft's center of gravity in response to the aircraft's current flight mode being approach mode, leveling mode, or ground mode. This operation effectively avoids unexpected changes in handling characteristics caused by center of gravity estimation deviations during special flight phases. When the aircraft exits a high-maneuver state (e.g., the overload returns to the 0.8g–1.3g range) or leaves the special flight mode, the center of gravity latching is automatically released, and real-time estimation is restored, ensuring reliability during special phases without affecting the center of gravity tracking accuracy during normal flight.

[0011] Secondly, embodiments of this application provide a flight control system, which may include: a data acquisition unit configured to acquire measurement signals from an atmospheric data system, an inertial navigation system, and a flight control system; and a processor configured to: calculate an aircraft center of gravity signal based on the measurement signals; map the aircraft center of gravity into a fuzzy center of gravity signal corresponding to a center of gravity interval according to a preset center of gravity partition; and generate control surface gains based on the fuzzy center of gravity signal, wherein the fuzzy center of gravity signal of different center of gravity intervals corresponds to different control surface gains.

[0012] In one optional implementation, the fuzzy center of gravity signal includes a front center of gravity signal, a middle center of gravity signal, and a rear center of gravity signal. The processor configured to map the aircraft's center of gravity into a fuzzy center of gravity signal corresponding to a center of gravity interval according to a preset center of gravity partition is further configured to: convert the aircraft's center of gravity with a value greater than or equal to Xcg1 and less than Xcg2 into a front center of gravity signal; convert the aircraft's center of gravity with a value greater than or equal to Xcg2 and less than Xcg3 into a middle center of gravity signal; and convert the aircraft's center of gravity with a value greater than or equal to Xcg3 and less than or equal to Xcg4 into a rear center of gravity signal.

[0013] In one alternative implementation, the measurement signals include aileron deflection and engine thrust. During takeoff, the aileron deflection and engine thrust both correct the aircraft's center of gravity forward.

[0014] In one alternative implementation, the processor is further configured to: limit the rate of change of the aircraft's center of gravity to meet a preset threshold for the rate of change of the center of gravity; and perform filtering processing on the aircraft's center of gravity.

[0015] In an alternative implementation, the processor is further configured to perform a latching operation on the aircraft's center of gravity in response to the aircraft's current flight mode and / or overload value.

[0016] In one alternative implementation, the processor configured to perform a latching operation on the aircraft's center of gravity in response to the aircraft's current flight mode and / or overload value is further configured to: latch the aircraft's center of gravity in response to an overload greater than 1.3g or less than 0.8g, or latch the aircraft's center of gravity in response to the aircraft's current flight mode being approach mode, leveling mode, or ground mode.

[0017] Thirdly, embodiments of this application provide an aircraft, the aircraft including the flight control system as described in any of the preceding claims.

[0018] The flight control method and system provided in this application have at least one of the following advantages: (1) This application comprehensively utilizes atmospheric data, inertial navigation data, and flight control system data for center of gravity estimation. These real-time flight data are highly reliable. Unlike traditional methods that rely on manual input of values, this method is entirely based on signals automatically collected by the system, fundamentally eliminating errors that may be caused by human input and ensuring the high reliability of the center of gravity estimation results.

[0019] (2) In this application, the algorithm model not only considers the influence of engine thrust on the aircraft's center of gravity, but also the influence of ailerons on the aircraft's center of gravity. This modeling approach enables the algorithm to accurately calculate the center of gravity of the entire flight envelope, including takeoff and go-around phases, and is also applicable to aircraft using advanced control laws such as "aileron droop lift enhancement". By introducing these variables, the calculation accuracy of the center of gravity estimation is improved.

[0020] (3) This application optimizes the estimated center of gravity signal by limiting the rate change and designing a partition. Limiting the rate change avoids the impact of signal abrupt changes on the aircraft's handling characteristics and improves flight quality; the partition design provides great convenience for downstream control logic. More importantly, the fuzzy center of gravity signal output after partition design can be directly used for parameter tuning of the elevator gain control law, which can effectively improve the problem of insufficient stick force during rear center of gravity test flights, thereby expanding the aircraft's operating envelope and greatly enhancing the aircraft's commercial competitiveness. Attached Figure Description

[0021] To gain a more detailed understanding of the manner in which the features of this application are described above, reference can be made to the various embodiments for a more specific description of the content briefly outlined above, some of which are illustrated in the accompanying drawings. However, it should be noted that the drawings only illustrate certain typical aspects of this application and should not be considered as limiting its scope, as this description may allow for other equivalent aspects.

[0022] Figure 1 This is a schematic diagram of a flight control method according to an embodiment of this application.

[0023] Figure 2 This is a schematic diagram of an aircraft center of gravity signal estimation logic according to an embodiment of this application.

[0024] Figure 3 This is a schematic diagram of an aircraft center of gravity signal estimation control architecture according to an embodiment of this application.

[0025] Figure 4 This is a schematic diagram illustrating the effect of aileron deflection and engine thrust on the center of gravity of an aircraft according to one embodiment of this application.

[0026] Figure 5 This is a schematic diagram of a flight control system according to an embodiment of this application. Detailed Implementation

[0027] The present application will be further described below with reference to specific embodiments and accompanying drawings, but this should not be construed as limiting the scope of protection of the present application. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the present application as detailed in the appended claims.

[0028] The terms "first," "second," etc., used in this application are used to distinguish identical or similar items, without limiting the quantity or order. "At least one" as used in this application refers to one or more; "multiple" refers to two or more. The term "or" and its variations can mean "and / or." "And / or" as used in this application describes the relationship between related objects, and can represent the following situations: A exists alone, A and B exist simultaneously, or B exists alone, where A and B can be singular or plural. The character " / " used in this application can indicate that the preceding and following related objects are in an "or" relationship. Additionally, the symbol " / " can also represent a division sign.

[0029] As used in this application, "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, at least one of a, b, or c can represent the following: a, b, c; a and b; a and c; b and c; a, b, and c. Each of a, b, and c can be an element or a set containing one or more elements.

[0030] Currently, the industry commonly uses a real-time estimation method based on a linear model for real-time aircraft center of gravity estimation. This method mainly collects key aerodynamic parameters such as the aircraft's angle of attack, flap angle, elevator deflection angle, and horizontal stabilizer position, and performs comprehensive calculations in conjunction with the aircraft weight signal provided by the flight management system. After obtaining the initial center of gravity estimate, it usually undergoes amplitude limiting and filtering optimization to smooth signal fluctuations and improve data stability.

[0031] However, this traditional approach has two significant inherent drawbacks: (1) The center of gravity calculation process is highly dependent on the aircraft's weight signal. This weight signal often needs to be manually input by the pilot in the cockpit. This manual intervention not only increases the operational burden on the crew, but more importantly, due to the uncertainty of human factors, the accuracy and reliability of the input data are difficult to guarantee, thus directly affecting the accuracy and credibility of the final center of gravity estimation result; (2) The real-time estimation method uses the traditional continuous interpolation method (for example, the control surface gain is subjected to a small linear interpolation every 0.01% change in the center of gravity value), making the center of gravity calculation extremely complex. This not only places a heavy real-time computational burden on the airborne computer, but also significantly increases the design complexity of the flight control law and the cost of airworthiness verification.

[0032] Figure 1 A schematic diagram of a flight control method 100 according to an embodiment of this application is illustrated. The flight control method 100 is executed by a measurement system, a master flight control law computer, and actuators.

[0033] In step 102, measurement signals from the atmospheric system, inertial navigation system, and flight control system are acquired. The flight control system in this application acquires measurement signals from the atmospheric data system, inertial navigation system (INS), and flight control system (Flight Control) in real time to establish a reliable data input foundation. Specifically, the atmospheric data system uses sensors such as pitot tubes and angle-of-attack wind vanes to measure the aircraft's altitude. ,Mach number and angle of attack The system establishes the aircraft's external aerodynamic environment; the inertial navigation system provides the aircraft's attitude angles and overload information as an inertial reference for center of gravity estimation, where overload information may include dynamic acceleration, which is defined as the quotient of lift divided by gravity; the flight control system provides real-time feedback on flap and slat deflection through various control surface sensors. Aileron deflection elevator deflection and tail deviation Combined with the engine thrust provided by the engine system The aircraft's control surface configuration and dynamic state are reconstructed. The measured signals, after being processed by a filtering algorithm, are used as input variables for subsequent center of gravity estimation.

[0034] In step 104, the aircraft's center of gravity is calculated based on the measured signal. According to flight dynamics principles, the offset of the real-time center of gravity position relative to the reference center of gravity is proportional to the ratio of the pitch moment coefficient to the lift coefficient. As an example, and not a limitation, the aircraft's real-time center of gravity can be calculated using the following formula: X cg =X cg_bias – ΔCm / ΔCL Among them, X cg X represents the estimated center of gravity of the aircraft; cg_bias The reference center of gravity position represents the center of gravity of each aircraft model when identifying the pitch moment coefficient during wind tunnel testing or parameter identification flight tests; ΔCm is the real-time pitch moment coefficient increment of the aircraft; ΔCL is the real-time lift coefficient increment of the aircraft. During the center of gravity estimation process, the system uses real-time measured parameters such as altitude, Mach number, angle of attack, flap / slat deflection, aileron deflection, elevator deflection, horizontal stabilizer deflection, and engine thrust as input variables. By querying a preset aerodynamic data interpolation table, it interpolates and calculates the lift coefficient increment (ΔCL) and pitch moment coefficient increment (ΔCm) in real-time under the current flight condition. Subsequently, the ratio of these two values ​​is used to calculate the offset of the real-time center of gravity relative to the reference center of gravity, and this offset is compared with the reference center of gravity position (X). cg_bias The superposition operation is performed to calculate the final real-time center of gravity position of the aircraft.

[0035] In optional step 106, the rate of change of the aircraft's center of gravity is limited, and the aircraft's center of gravity is filtered.

[0036] The purpose of limiting the rate of change of the center of gravity (CG) is to eliminate unintended maneuvering risks caused by low-frequency noise or transient changes in the CG signal. In terms of specific parameter settings, the upper and lower thresholds of the CG rate of change limit are selected based on a comprehensive consideration of the aircraft's base fuel consumption rate and the additional CG drift that may occur due to passenger movement within the cabin. The flight control system fully considers the aircraft's takeoff weight, real-time fuel flow, and other specific design characteristics, matching differentiated limit values ​​for different aircraft models. This process effectively smooths the dynamic changes in the CG signal, ensuring that the output signal conforms to physical laws, thereby improving the reliability and safety of the CG signal.

[0037] For example, the upper and lower limits of the center of gravity change rate can be set from -1% MAC / s to 1% MAC / s, which is the average aerodynamic chord (MAC) of the center of gravity moving by one percent per second. During flight, if the aircraft encounters a sudden strong vertical gust, causing the angle of attack sensor to detect a drastic change in value in a very short instant (e.g., within 0.1 seconds), the algorithm, due to the sudden change in angle of attack, will cause the calculated center of gravity signal to shift forward by 0.5% MAC within 0.1 seconds. The instantaneous change rate of the center of gravity signal is as high as 5% MAC / s (i.e., 0.5% ÷ 0.1 seconds), which obviously far exceeds the center of gravity movement speed that the aircraft can achieve under actual physical load changes. By using the reasonable rate limit thresholds preset in this section, such as setting the upper and lower limits of the center of gravity change rate to -1% MAC / s to 1% MAC / s, this abnormally high rate of change can be automatically identified and suppressed. The flight control system does not allow the center of gravity signal to jump by 0.5% directly within 0.1 seconds. Instead, it forces a smooth transition and gradually moves the center of gravity signal to its final position over 0.5 seconds, according to a positive maximum MAC / second rate limit.

[0038] Filtering the aircraft's center of gravity involves using a low-pass filter algorithm to remove high-frequency noise components from the center of gravity signal. In actual flight, the calculated original center of gravity signal may exhibit high-frequency, repetitive oscillations around a specific value. Directly inputting such a signal into the control law to control the control surface gain can easily lead to unnecessary and frequent fluctuations in the control surface gain. Effective suppression through the low-pass filter outputs a smooth and stable center of gravity signal, preventing control surface jitter and thus ensuring the stability of the aircraft's longitudinal control and flight quality.

[0039] In optional step 106, a latching operation is performed on the aircraft's center of gravity in response to the aircraft's current flight mode and / or overload value.

[0040] The center of gravity signal latching operation is triggered by real-time monitoring of the aircraft's current flight mode and real-time overload value. The real-time overload value (i.e., dynamic acceleration g) is defined as the ratio of the aircraft's real-time lift (N) to its real-time gravity (M), characterizing the intensity of the aircraft's maneuvering flight. When the aircraft enters a high-maneuvering flight state (e.g., real-time overload greater than 1.3g or less than 0.8g), or when the aircraft's current flight mode is approach mode, leveling mode, or ground mode, the real-time center of gravity estimation result often has a large error due to drastic changes in the aerodynamic environment or ground effect interference. In this case, the flight control system will automatically trigger the latching logic, forcibly maintaining the center of gravity value at the moment before the maneuver occurred until the relevant triggering logic is released. This mechanism effectively avoids unexpected changes in handling characteristics caused by center of gravity estimation deviations during special flight phases, providing an important guarantee for flight safety. When the aircraft exits a high-G maneuver state (e.g., the overload returns to the range of 0.8g to 1.3g) or leaves a special flight mode, the center of gravity latch is automatically released, and real-time estimation is restored. This ensures the reliability of the special phase without affecting the center of gravity tracking accuracy during normal flight.

[0041] In step 108, based on the preset center of gravity partition, the center of gravity of the aircraft is mapped to a fuzzy center of gravity signal corresponding to a center of gravity interval.

[0042] The center of gravity partitioning is defined as follows: the center of gravity interval [Xcg1, Xcg2) is defined as the front center of gravity, [Xcg2, Xcg3) is defined as the middle center of gravity, and [Xcg3, Xcg4] is defined as the rear center of gravity. The fuzzy center of gravity signal can include the front center of gravity signal, the middle center of gravity signal, and the rear center of gravity signal. Based on the preset center of gravity partitioning, mapping the aircraft's center of gravity to a fuzzy center of gravity signal corresponding to a center of gravity interval can include: converting aircraft center of gravity values ​​greater than or equal to Xcg1 and less than Xcg2 into a front center of gravity signal; converting aircraft center of gravity values ​​greater than or equal to Xcg2 and less than Xcg3 into a middle center of gravity signal; and converting aircraft center of gravity values ​​greater than or equal to Xcg3 and less than or equal to Xcg4 into a rear center of gravity signal.

[0043] For example, suppose the center of gravity safety envelope of a certain type of aircraft is strictly limited to between 0% and 30% of the mean aerodynamic chord (MAC), with values ​​exceeding 30% considered unacceptable. The corresponding center of gravity zones are set as follows: Xcg1 = 0% MAC (Absolute leading limit of safety envelope) Xcg2 = 10% MAC (the dividing point between the front center of gravity and the middle center of gravity) Xcg3 = 20% MAC (the dividing point between the center of gravity and the rear center of gravity) Xcg4 = 30% MAC (absolute back limit of the safety envelope, i.e., the extreme boundary of the back center of gravity) Based on the above thresholds, the mapping rules for the fuzzy centroid signal are as follows: Forward center of gravity signal: When the real-time center of gravity value is greater than or equal to 0% MAC and less than 10% MAC, the flight control system maps it to a forward center of gravity signal. At this time, the aircraft has strong longitudinal static stability, but relatively low control sensitivity.

[0044] Intermediate center of gravity signal: When the real-time center of gravity value is greater than or equal to 10% MAC and less than 20% MAC, the flight control system maps it to an intermediate center of gravity signal. At this time, the aircraft is in a relatively ideal balance state, balancing stability and maneuverability.

[0045] Aft center of gravity signal: When the real-time center of gravity value is greater than or equal to 20% MAC and less than or equal to 30% MAC, the flight control system maps it to an aft center of gravity signal. At this time, the aircraft's handling response is more sensitive, but the static stability margin is reduced.

[0046] Illegal / Disallowed Status: When the real-time centroid value is greater than 30% MAC (i.e., exceeds the boundary of Xcg4) or less than 0% MAC, the value is judged as an illegal value that is not allowed because it exceeds the preset safe range.

[0047] In step 110, control surface gains are generated based on the fuzzy center of gravity signal, where different fuzzy center of gravity ranges correspond to different control surface gains. The function of control surface gains is to convert the angle of the control stick into the angle of the control surfaces. Appropriate gains allow the pilot to obtain reasonable control surface outputs and appropriate aircraft responses under comfortable control stick input. Specifically, the flight control system presets multiple sets of control surface gain parameters for different center of gravity characteristics. When the fuzzy center of gravity signal is "forward center of gravity," the flight control system will automatically call the first set of control surface gains adapted to the forward center of gravity characteristics; when the fuzzy center of gravity signal is "intermediate center of gravity," it will automatically call the second set of control surface gains adapted to the intermediate center of gravity characteristics; and when the fuzzy center of gravity signal is "rear center of gravity," it will switch to the third set of gains adapted to the rear center of gravity characteristics.

[0048] The above operations can specifically improve flight quality. The aerodynamic characteristics of an aircraft vary greatly at different center of gravity positions. For example, when the center of gravity is in the "forward" range (e.g., 0%-10% MAC), the aircraft has strong longitudinal static stability, but the control sensitivity will decrease significantly. At this time, the control law needs to call a set of "high-gain" control surface parameters to enhance the deflection efficiency of the elevator and ensure that the aircraft has sufficient control response during takeoff or approach. Conversely, when the center of gravity is in the "rear" range (e.g., 20%-30% MAC), the aircraft's static stability margin decreases and the control response becomes more sensitive. At this time, the system automatically switches to a set of "low-gain" or control surface parameters with specific damping compensation, which can effectively prevent pilot-induced oscillations caused by overly sensitive control, thereby maintaining stable flight quality at the edge of the flight envelope.

[0049] Furthermore, compared to traditional continuous interpolation methods (e.g., performing minute linear interpolation on control surface gain for every 0.01% change in center of gravity), the fuzzy signal-based partitioning strategy significantly simplifies the mathematical model and software architecture of the control law. It transforms the complex continuous nonlinear control problem into a linear control problem at several typical operating points. This not only reduces the real-time computational burden on the onboard computer but, more importantly, significantly lowers the design complexity and airworthiness verification cost of the flight control law. Engineers only need to perform independent stability and robustness verification for three typical fuzzy states—"before," "during," and "after"—without exhaustively testing every continuous numerical point within the center of gravity envelope, thus improving R&D efficiency while ensuring flight safety.

[0050] Figure 2 A schematic diagram illustrating the aircraft center of gravity signal estimation logic according to an embodiment of this application is provided.

[0051] like Figure 2 As shown, the aircraft center of gravity signal estimation is achieved by collecting raw flight data through the measurement system 201, performing algorithm calculations by the main flight control law computer 206, and finally having the actuator 207 responsible for converting control commands into physical actions.

[0052] Specifically, the measurement system 201 includes an atmospheric system, an inertial navigation system, and a flight control system, which provide flight parameters such as airspeed, altitude, attitude angle, and angular rate, respectively. These measurement signals are sent to the main flight control law computer 206, where the lift coefficient estimation logic module 202 and the pitch moment coefficient estimation logic module 203 first perform real-time calculations of the aerodynamic characteristics. Their outputs are then input to the center of gravity calculation logic module 204 to derive the current center of gravity position of the aircraft. This center of gravity signal is then transmitted to the control surface control logic module 205, which generates corresponding control surface deflection commands based on a preset control law and the control surface gain corresponding to the fuzzy signal. Finally, the control surface deflection commands are sent to the main control surface actuators in the actuator 207, driving the main control surfaces 208 (such as elevators, ailerons, or rudders) to produce actual deflections, thereby changing the aerodynamic attitude of the aircraft and completing closed-loop control. The entire process embodies a complete flight control link from sensing and calculation to execution, ensuring that the aircraft maintains good handling qualities and stability at different flight stages and center of gravity states.

[0053] The lift coefficient estimation logic module 202 is a unit in the main flight control law computer 206 used to calculate the aircraft's aerodynamic state in real time. This module mainly calculates the aircraft's current total lift coefficient based on the aircraft's aerodynamic layout parameters, real-time angle of attack, Mach number, and current control surface deflection, using aerodynamic model formulas or lookup tables.

[0054] The pitch moment coefficient estimation logic module 203, as another aerodynamic calculation unit in the main flight control law computer, is responsible for estimating the aircraft's current pitch moment coefficient in real time based on flight status data (such as attitude angles and angular rates) provided by the measurement system. This coefficient is an indicator that measures the aircraft's longitudinal balance state and stability trend.

[0055] The gravity calculation logic module 204 receives output data from the lift coefficient estimation logic module 202 and the pitch moment coefficient estimation logic module 203, calculates the aircraft's center of gravity position based on the aforementioned calculation formula, maps this center of gravity position to a corresponding fuzzy center of gravity signal, and then outputs the fuzzy center of gravity signal to the control surface logic module 205 for subsequent flight control command generation. The gravity calculation logic module 204 is a key component in achieving stable aircraft control, ensuring the accuracy and safety of control surface commands by dynamically estimating the center of gravity position.

[0056] The actuator 207 is the mechanism that translates the control algorithm into physical actions. It receives instructions from the control surface control logic module 205 and physically drives the main control surface 208 by driving the main control surface actuator, thereby generating aerodynamic torque and achieving final control of the aircraft's attitude or trajectory.

[0057] Figure 3A schematic diagram of an aircraft center of gravity signal estimation control architecture according to an embodiment of this application is explained.

[0058] like Figure 3 As shown, the measurement system acquires flight status data, including altitude (12), flap / slat deflection (13), Mach number (14), aileron deflection (15), angle of attack (16), elevator deflection (17), horizontal stabilizer deflection (18), and engine thrust (19). This data is input into interpolation table (10), and through interpolation calculations using the aerodynamic characteristic database, outputs the pitch moment coefficient increment (20, ΔCm) and lift coefficient increment (21, ΔCL). Subsequently, the division operation module (11) calculates ΔCm / ΔCL to obtain the center of gravity data offset, which is then superimposed with the reference center of gravity data (22) to finally output the real-time center of gravity position signal. This step, through multi-parameter fusion and interpolation calculations, achieves dynamic estimation of the center of gravity position during flight, providing fundamental data for subsequent control laws.

[0059] The real-time center of gravity signal sequentially passes through a rate limiting stage 23 (limiting the rate of change to avoid abrupt control changes), a low-pass filtering stage 24 (filtering out high-frequency noise and improving signal quality), and a limiting stage 25 (limiting the signal range to prevent over-limit anomalies). It then enters a latching stage 26. When the overload Nz27 > 1.3g or < 0.8g, or when the aircraft is in automatic flight approach mode 28, leveling mode 29, or ground mode 30, the center of gravity signal CG_ESTIMATE is latched to ensure stable control characteristics during critical phases. The latched signal is then processed by a fuzzy logic stage 31, dividing it into forward center of gravity, intermediate center of gravity, and aft center of gravity according to the intervals [Xcg1,Xcg2), [Xcg2,Xcg3), and [Xcg3,Xcg4], generating a fuzzy signal CG_ESTIMATE_fuzzy to simplify subsequent control logic.

[0060] The system dynamically adjusts the elevator, aileron, and rudder gains based on the processed fuzzy signals: increasing the gain at the forward center of gravity to enhance pitch control torque, and decreasing the gain at the aft center of gravity to avoid oversensitivity. The same stick input corresponds to different control surface deflections at different centers of gravity, ensuring consistent handling quality across the entire center of gravity range. The final generated elevator, aileron, and other commands drive the control surfaces through actuators, achieving precise control of the aircraft's attitude and ensuring flight safety and stability.

[0061] Figure 4 A schematic diagram illustrating the effect of aileron deflection and engine thrust on the aircraft's center of gravity according to one embodiment of this application is provided.

[0062] Traditional lift coefficient estimation algorithms typically consider the dominant contributions of angle of attack and elevator deflection to lift. For ailerons, traditional algorithms are often based on idealized assumptions: that for aircraft with symmetrically deflected ailerons, when the two ailerons deflect differentially (in opposite directions) to generate rolling moment, the increase in lift on one wing cancels out the decrease in lift on the other wing, and therefore the effect on the total lift coefficient is considered zero or negligible.

[0063] However, for some modern aircraft with advanced flight control laws, the following situation can significantly affect the total lift: the left and right ailerons deflect downwards at the same time. Specifically, during low-speed or high-lift demand phases, the left and right ailerons may deflect downwards simultaneously as lift-enhancing devices, which will directly and significantly increase the wing camber and total lift.

[0064] To quantify the aforementioned effects, according to one embodiment of this application, a new parameter—aileron deflection—is introduced into the lift coefficient estimation logic, aiming to address the estimation bias of the aircraft's center of gravity during the takeoff phase of traditional algorithms. Figure 4 As shown, if aileron deflection is not considered, the estimated center of gravity of the aircraft would be further back during takeoff. Therefore, during takeoff, aileron deflection corrects the center of gravity forward. In other phases of flight, aileron deflection has no significant impact on the estimated center of gravity.

[0065] In conventional pitch moment estimation logic, the algorithm mainly focuses on the moment generated by aerodynamic forces, namely the moment components caused by wing lift, horizontal stabilizer load, and elevator deflection. However, this purely aerodynamic estimation often ignores the direct contribution of the propulsion system to the longitudinal moment, leading to deviations in the estimation results when thrust changes drastically (such as go-around, aborted takeoff, or single-engine failure).

[0066] To quantify the above effects, according to one embodiment of this application, engine thrust is introduced as a correction parameter into the pitch moment coefficient estimation logic. For example... Figure 4 As shown in the diagram, taking an aircraft type that generates a nose-down moment due to increased thrust as an example, if engine thrust is not considered, the estimated center of gravity of the aircraft would be further back during takeoff. Therefore, during takeoff, engine thrust corrects the aircraft's center of gravity forward. In other phases of flight, engine thrust has no significant impact on the estimated center of gravity.

[0067] Figure 5 A schematic diagram of a flight control system 500 according to an embodiment of this application is illustrated.

[0068] like Figure 5As shown, the flight control system 500 may include a data acquisition unit 502 and a processor 504. The data acquisition unit 502 is configured to acquire measurement signals from an atmospheric data system, an inertial navigation system, and the flight control system. The processor 504 is configured to: calculate the aircraft's center of gravity based on the measurement signals; map the aircraft's center of gravity to a fuzzy center of gravity signal corresponding to a center of gravity interval according to a preset center of gravity partition; and generate control surface gains based on the fuzzy center of gravity signal, wherein the fuzzy center of gravity signal for different center of gravity intervals corresponds to different control surface gains.

[0069] The processor, configured to map the aircraft's center of gravity into a fuzzy center of gravity signal corresponding to a center of gravity interval based on a preset center of gravity partition, is further configured to: convert the aircraft's center of gravity with a value greater than or equal to Xcg1 and less than Xcg2 into a forward center of gravity signal; convert the aircraft's center of gravity with a value greater than or equal to Xcg2 and less than Xcg3 into an intermediate center of gravity signal; and convert the aircraft's center of gravity with a value greater than or equal to Xcg3 and less than or equal to Xcg4 into a rear center of gravity signal.

[0070] The processor 504 is also configured to: limit the rate of change of the aircraft's center of gravity to meet a preset threshold for the rate of change of the center of gravity; and perform filtering processing on the aircraft's center of gravity.

[0071] The processor 504 is also configured to perform a latching operation on the aircraft's center of gravity in response to the aircraft's current flight mode and / or overload value.

[0072] The processor configured to perform a latching operation on the aircraft's center of gravity in response to the aircraft's current flight mode and / or overload value is further configured to: latch the aircraft's center of gravity in response to an overload greater than 1.3g or less than 0.8g, and latch the aircraft's center of gravity in response to the aircraft's current flight mode being approach mode, leveling mode, or ground mode.

[0073] The foregoing description includes examples of various aspects of the claimed subject matter. It is certainly impossible to describe every conceivable combination of components or methods for the purpose of depicting the claimed subject matter, but those skilled in the art will recognize that many further combinations and arrangements of the claimed subject matter are possible. Thus, the disclosed subject matter is intended to cover all such changes, modifications, and variations that fall within the spirit and scope of the appended claims.

Claims

1. A flight control method, the method comprising: Acquire measurement signals from atmospheric data systems, inertial navigation systems, and flight control systems; The aircraft's center of gravity is calculated based on the measured signals. Based on a preset center of gravity partition, the aircraft's center of gravity is mapped to a fuzzy center of gravity signal corresponding to a center of gravity interval. The fuzzy center of gravity signal includes a forward center of gravity signal, a middle center of gravity signal, and a rear center of gravity signal. Mapping the aircraft's center of gravity to a fuzzy center of gravity signal corresponding to a center of gravity interval includes: The aircraft center of gravity with a value greater than or equal to Xcg1 and less than Xcg2 is converted into a forward center of gravity signal; The aircraft's center of gravity, with a value greater than or equal to Xcg2 and less than Xcg3, is converted into an intermediate center of gravity signal; or The aircraft's center of gravity values ​​greater than or equal to Xcg3 and less than or equal to Xcg4 are converted into rear center of gravity signals. Where Xcg1, Xcg2, Xcg3, and Xcg4 are the mean aerodynamic chord (MAC) values ​​at different proportions, satisfying: Xcg1 < Xcg2 < Xcg3 < Xcg4, and Xcg1 is 0% MAC, Xcg4 is 30% MAC; and The control surface gain is generated based on the fuzzy centroid signal, wherein the fuzzy centroid signal in different centroid intervals corresponds to different control surface gains.

2. The method as described in claim 1, characterized in that, The measurement signals include aileron deflection and engine thrust. During takeoff, the aileron deflection corrects the aircraft's center of gravity forward, as does the engine thrust.

3. The method as described in claim 1, characterized in that, The method further includes: The rate of change of the aircraft's center of gravity is limited to meet a preset threshold. The center of gravity of the aircraft is filtered.

4. The method as described in claim 1, characterized in that, The method further includes: In response to the aircraft's current flight mode and / or overload value, a latching operation is performed on the aircraft's center of gravity.

5. The method as described in claim 4, characterized in that, The latching operation on the aircraft's center of gravity in response to the aircraft's current flight mode and / or overload value includes: In response to an overload greater than 1.3g or less than 0.8g, the aircraft's center of gravity is latched, or In response to the aircraft's current flight mode being approach mode, leveling mode, or ground mode, the aircraft's center of gravity is locked.

6. A flight control system, the system comprising: The data acquisition unit is configured to acquire measurement signals from the atmospheric data system, inertial navigation system, and flight control system. The processor is configured as follows: The aircraft's center of gravity is calculated based on the measured signals. Based on a preset center of gravity partition, the aircraft's center of gravity is mapped and converted into a fuzzy center of gravity signal corresponding to a center of gravity interval. The fuzzy center of gravity signal includes a forward center of gravity signal, a middle center of gravity signal, and a rear center of gravity signal. Mapping the aircraft's center of gravity into a fuzzy center of gravity signal corresponding to a center of gravity interval includes: The aircraft center of gravity with a value greater than or equal to Xcg1 and less than Xcg2 is converted into a forward center of gravity signal; The aircraft's center of gravity, with a value greater than or equal to Xcg2 and less than Xcg3, is converted into an intermediate center of gravity signal; or The aircraft's center of gravity values ​​greater than or equal to Xcg3 and less than or equal to Xcg4 are converted into rear center of gravity signals. Where Xcg1, Xcg2, Xcg3, and Xcg4 are the mean aerodynamic chord (MAC) values ​​at different proportions, satisfying: Xcg1 < Xcg2 < Xcg3 < Xcg4, and Xcg1 is 0% MAC, Xcg4 is 30% MAC; and The control surface gain is generated based on the fuzzy centroid signal, wherein the fuzzy centroid signal in different centroid intervals corresponds to different control surface gains.

7. The system as described in claim 6, characterized in that, The measurement signals include aileron deflection and engine thrust. During takeoff, the aileron deflection and engine thrust both correct the aircraft's center of gravity forward.

8. The system as described in claim 6, characterized in that, The processor is also configured to: The rate of change of the aircraft's center of gravity is limited to meet a preset threshold. The center of gravity of the aircraft is filtered.

9. The system as described in claim 6, characterized in that, The processor is also configured to: In response to the aircraft's current flight mode and / or overload value, a latching operation is performed on the aircraft's center of gravity.

10. The system as described in claim 9, characterized in that, The processor configured to perform a latching operation on the aircraft's center of gravity in response to the aircraft's current flight mode and / or overload value is further configured to: In response to an overload greater than 1.3g or less than 0.8g, the aircraft's center of gravity is latched, or In response to the aircraft's current flight mode being approach mode, leveling mode, or ground mode, the aircraft's center of gravity is locked.

11. An aircraft comprising a flight control system as claimed in any one of claims 6-10.

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