An Active Center of Gravity Adjustment Control Method for Advanced Aircraft Variant Processes

Abstract

This application relates to an active center of gravity adjustment control method for advanced aircraft during morphing processes. The method includes: real-time acquisition of the aircraft's morphing state information and synchronous acquisition of flight state information to obtain an input vector; wherein the morphing state information includes wing sweep angle, aspect ratio, and flap deflection angle, and the flight state information includes angle of attack, flight speed, altitude, pitch angle, and acceleration; calculating the initial aerodynamic center position based on the input vector using an aerodynamic center prediction function, and determining the aerodynamic center position based on the change in the aerodynamic center position; calculating the target center of gravity position based on the aircraft's average aerodynamic chord length and the aerodynamic center position, and obtaining the target center of gravity position adjustment amount; and adjusting the aircraft's center of gravity to the target center of gravity position using a center of gravity adjustment actuator. This application can provide active center of gravity adjustment for advanced aircraft morphing processes, suppressing attitude disturbances and ensuring flight safety through information acquisition and aerodynamic center calculation.

Description

Technical Field

[0001] This application relates to the field of aircraft control technology, and in particular to an active center of gravity adjustment control method for advanced aircraft variant processes. Background Technology

[0002] In today's rapidly developing aerospace technology, advanced aircraft with structural variability capabilities have become an important development direction for improving flight performance. These aircraft can dynamically adjust structural parameters according to different flight missions and operating conditions, optimizing aerodynamic performance and improving flight efficiency. They are widely used in advanced aircraft platforms such as high-maneuverability fighter jets and long-endurance unmanned aerial vehicles (UAVs). The center of gravity position, as a core parameter determining the full-envelope flight stability, attitude control accuracy, and control response characteristics of an aircraft, directly affects flight safety and control quality. During aircraft variability, the dynamic changes in structural morphology inevitably lead to significant alterations in mass distribution, resulting in a rapid shift of the center of gravity. If the shifted center of gravity cannot be accurately controlled in a timely manner, it can easily compromise the longitudinal static stability of the aircraft, causing attitude disturbances, control response lag, and in severe cases, even loss of flight control.

[0003] In existing technologies, aircraft center of gravity control technologies mainly include:

[0004] First, the adjustment method based on the fuel management system changes the center of gravity position by transferring fuel between different fuel tanks. However, this method has a limited fuel transfer rate and a long adjustment response time, which cannot meet the real-time compensation requirements for rapid center of gravity shifts during high-speed configuration changes. Furthermore, it is highly dependent on liquid fuel reserves; when fuel levels are low, the center of gravity adjustment capability significantly decreases, making it difficult to adapt to the operational requirements of the aircraft throughout its entire flight cycle. Second, the fixed counterweight design adjusts the center of gravity by using preset fixed counterweight blocks. However, the position and mass of the counterweights cannot be dynamically adjusted, lacking flexibility and making it difficult to adapt to the center of gravity control requirements under different flight configurations. Third, the open-loop compensation mechanism based on preset variant states compensates for the center of gravity according to pre-set variant state parameters. However, this mechanism cannot perceive real-time state and structural dynamic changes during flight, resulting in insufficient adjustment accuracy and failing to guarantee constant longitudinal static stability during configuration changes. Simultaneously, this mechanism has low coupling with the flight control system, making it difficult to achieve coordinated action between adjustment and attitude control when attitude disturbances are caused by center of gravity shifts.

[0005] Therefore, it is necessary to improve one or more of the problems existing in the above-mentioned related technical solutions.

[0006] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0007] The purpose of this disclosure is to provide an active center of gravity adjustment control method for advanced aircraft variants, thereby overcoming, at least to some extent, one or more problems caused by the limitations and defects of related technologies.

[0008] This application provides an active center of gravity adjustment control method for advanced aircraft variant processes, including:

[0009] The variant state information of the aircraft is collected in real time, and the flight state information is acquired simultaneously to obtain the input vector; wherein, the variant state information includes wing sweep angle, aspect ratio and flap deflection angle, and the flight state information includes angle of attack, flight speed, altitude, pitch angle and acceleration;

[0010] Based on the input vector, the initial aerodynamic center position is calculated using the aerodynamic center prediction function, and the aerodynamic center position is determined based on the change in the aerodynamic center position.

[0011] The target center of gravity position is calculated based on the longitudinal static stability using the aircraft's average aerodynamic chord length and the aerodynamic center position, and the target center of gravity position adjustment amount is obtained.

[0012] The center of gravity of the aircraft is adjusted to the target center of gravity position by the center of gravity adjustment actuator.

[0013] In one possible implementation, the step of real-time acquisition of variant state information of the aircraft and synchronous acquisition of flight state information to obtain the input vector includes:

[0014] Configuration status sensors are installed in the variable configuration parts of the aircraft to collect configuration parameters in real time; wherein, the variable configuration parts include the wing rotation pivot, the tail fin mounting point and the variable aspect ratio mechanism, and the configuration status sensors include photoelectric encoders, laser displacement sensors and angle sensors;

[0015] Flight status parameters are obtained through the aircraft's flight control system;

[0016] The variant state information and the flight state information are processed by anti-aliasing filtering and sensor fusion algorithms to obtain the input vector.

[0017] In one possible implementation, the input vector is:

[0018]

[0019] in, For the input vector, For wing sweep angle, For aspect ratio, For the flap deflection angle, For the angle of attack, For flight speed, For height, The pitch angle, For lateral acceleration, This is the longitudinal acceleration.

[0020] In one possible implementation, the step of calculating the change in aerodynamic center position based on the input vector using the aerodynamic center prediction function includes:

[0021] The aerodynamic center prediction function is obtained by using a pre-established wind tunnel test database, CDF simulation data, or online modeling.

[0022] Substitute the input vector into the aerodynamic center prediction function to calculate the initial aerodynamic center position;

[0023] The aerodynamic center position is determined by limiting the change in the position of the aerodynamic center using a saturation function.

[0024] In one possible implementation, the saturation function is:

[0025]

[0026] in, This represents the change in the position of the aerodynamic center. The location of the aerodynamic center. This represents the maximum change in the position of the aerodynamic center.

[0027] In one possible implementation, the step of calculating the target center of gravity position based on the longitudinal static stability using the aircraft's average aerodynamic chord length and the aerodynamic center position, and obtaining the target center of gravity position adjustment amount, includes:

[0028] Determine the desired longitudinal static stability based on the flight mission scenario;

[0029] Based on the aircraft's average aerodynamic chord length, the aerodynamic center position, and the desired longitudinal static stability margin, the target center of gravity position is obtained using the target center of gravity position formula.

[0030] When there are requirements for short-period damping ratio and natural frequency, the target centroid position is obtained through a multi-objective optimization problem;

[0031] The target center of gravity position adjustment amount is obtained based on the target center of gravity position and the current center of gravity position.

[0032] In one possible implementation, the formula for the target centroid position is:

[0033]

[0034] in, The target center of gravity position, For desired longitudinal static stability;

[0035] The multi-objective optimization problem is:

[0036]

[0037] in, As the first weighting coefficient, This is the second weighting coefficient. The third weighting coefficient, For short-cycle damping ratio, This is a reference value for the short-cycle damping ratio. It is a short-period natural frequency. This is a reference value for the short-period natural frequency.

[0038] In one possible implementation, the center of gravity adjustment actuator is controlled by a feedforward PID composite control, and the mechanism thrust formula is:

[0039]

[0040] in, For institutional thrust, As a proportion, For differential, For feedforward gain, This is the error in the position of the center of gravity. , This represents the rate of change of the center of gravity position error.

[0041] In one possible implementation, the step of adjusting the aircraft's center of gravity to the target center of gravity position via the center of gravity adjustment actuator further includes:

[0042] During the adjustment process of the center of gravity adjustment actuator, the flight control system corrects the pitch moment compensation term based on the real-time position of the slider and the predicted aerodynamic center; the calculation formula for the pitch moment compensation term is as follows:

[0043]

[0044] in, For pitch moment compensation, As the reference aerodynamic torque, For quality, It is the acceleration due to gravity. Adjustment amount for the target center of gravity position. It is the pitch angle.

[0045] In one possible implementation, the step of adjusting the aircraft's center of gravity to the target center of gravity position via the center of gravity adjustment actuator further includes:

[0046] Throughout the center of gravity adjustment process, the slider position, speed, and drive current are monitored, and the slider is stopped when any of these exceed the preset range.

[0047] The technical solution provided in this application may include the following beneficial effects:

[0048] This application relates to an active center of gravity adjustment control method for advanced aircraft during variability maneuvers. It can synchronously collect variability and flight status information in real time and form a precise input vector, avoiding variability prediction errors caused by information lag or missing dimensions. Furthermore, it accurately determines the aerodynamic center position by combining an aerodynamic center prediction function and scientifically calculates the target center of gravity position and adjustment amount based on longitudinal static stability, achieving precise targeted positioning of the center of gravity adjustment. Simultaneously, the center of gravity is quickly adjusted to the target position via a center of gravity adjustment actuator, effectively suppressing attitude disturbances caused by center of gravity shift during variability maneuvers, significantly improving the aircraft's flight stability and handling qualities, and ensuring the flight safety of advanced variability aircraft throughout its entire flight envelope.

[0049] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0050] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0051] Figure 1 This diagram illustrates a flowchart of an active center of gravity adjustment control method for advanced aircraft variants in an exemplary embodiment of this disclosure.

[0052] Figure 2 A detailed flowchart of step S100 of the active center of gravity adjustment control method for advanced aircraft variants in an exemplary embodiment of this disclosure is shown.

[0053] Figure 3 A detailed flowchart of step S200 of the active center of gravity adjustment control method for advanced aircraft variants in an exemplary embodiment of this disclosure is shown.

[0054] Figure 4 A detailed flowchart of step S300 of the active center of gravity adjustment control method for advanced aircraft variants in an exemplary embodiment of this disclosure is shown. Detailed Implementation

[0055] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that this disclosure will be more comprehensive and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0056] Furthermore, the accompanying drawings are merely illustrative of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0057] This example implementation first provides an active center of gravity adjustment control method for advanced aircraft variant processes. This method can be applied to a terminal device, such as a mobile terminal like a mobile phone, desktop computer, personal digital assistant, laptop, tablet, or smartwatch. (Reference) Figure 1 As shown, the method may include the following steps:

[0058] Step S100: Collect the variant state information of the aircraft in real time and simultaneously acquire the flight state information to obtain the input vector; wherein, the variant state information includes wing sweep angle, aspect ratio and flap deflection angle, and the flight state information includes angle of attack, flight speed, altitude, pitch angle and acceleration.

[0059] Step S200: Calculate the initial aerodynamic center position using the aerodynamic center prediction function based on the input vector, and determine the aerodynamic center position based on the change in the aerodynamic center position.

[0060] Step S300: Calculate the target center of gravity position based on the longitudinal static stability using the aircraft's average aerodynamic chord length and the aerodynamic center position, and obtain the target center of gravity position adjustment amount.

[0061] Step S400: Adjust the center of gravity of the aircraft to the target center of gravity position using the center of gravity adjustment actuator.

[0062] The aforementioned method can accurately address center of gravity shifts during advanced aircraft morphing processes. By synchronously collecting multi-dimensional state information in real time and processing it with specialized algorithms, it provides precise data support for center of gravity adjustment. Combined with aerodynamic center prediction functions and longitudinal static stability calculations, it achieves precise positioning of the target center of gravity. Furthermore, relying on a center of gravity adjustment actuator with feedforward PID composite control, it can complete center of gravity adjustment within seconds, with position errors controlled within ±0.5mm, significantly improving adjustment response speed and accuracy, and effectively solving the problems of slow response and fuel quantity limitations in traditional fuel management adjustments. At the same time, through the coordinated compensation of the flight control system and the center of gravity adjustment system, this method can suppress pitch attitude fluctuations during morphing processes to within ±0.4° and altitude fluctuations to within ±2m, successfully maintaining constant longitudinal static stability of the aircraft and significantly reducing the risk of attitude disturbances.

[0063] Below, we will refer to Figures 2 to 4 The steps of the method described above in this example embodiment will be explained in more detail.

[0064] In step S100, the variant state information of the aircraft is collected in real time, and the flight state information is acquired synchronously to obtain the input vector; wherein, the variant state information includes wing sweep angle, aspect ratio and flap deflection angle, and the flight state information includes angle of attack, flight speed, altitude, pitch angle and acceleration.

[0065] Understandably, variant state information directly reflects the dynamic adjustment of the aircraft configuration, while flight state information accurately characterizes its flight conditions. Real-time synchronous acquisition of both is the core data foundation for subsequent aerodynamic center prediction, target center of gravity calculation, and precise adjustment. The completeness and temporal consistency of these two types of information directly determine the response speed and control accuracy of active center of gravity adjustment, providing reliable input support for the entire closed-loop control process and serving as a prerequisite for resolving the center of gravity shift problem during variant processes.

[0066] In one embodiment, such as Figure 2 As shown, step S100 may include the following sub-steps:

[0067] In step S110, a configuration status sensor is installed on the variable configuration part of the aircraft to collect configuration parameters in real time; wherein, the variable configuration part includes the wing rotation pivot, the tail mounting point and the variable aspect ratio mechanism, and the configuration status sensor includes an optical encoder, a laser displacement sensor and an angle sensor.

[0068] It should be noted that the selected variable configuration parts are all key nodes where structural parameters change during the aircraft's transformation process, and the changes in these parameters are directly related to changes in aerodynamic characteristics. The corresponding sensors are matched to the measurement requirements of different parameters. For example, an optical encoder is used to capture the rotation angle of the wing's rotation pivot with its high-precision angle measurement capability to obtain the wing sweep angle; a laser displacement sensor is used to obtain the aspect ratio through linear displacement detection; and an angle sensor is used to collect the flap deflection angle. The three work together to achieve comprehensive and accurate capture of the transformation state parameters.

[0069] In step S120, flight status parameters are obtained through the flight control system of the aircraft.

[0070] It should be noted that the aircraft flight control system itself integrates a mature state detection module and data transmission channel, which can stably acquire core parameters such as angle of attack and flight speed. Moreover, its data acquisition frequency can be matched with the configuration state sensor, effectively avoiding the time sequence deviation between the two types of information, ensuring the accuracy of subsequent data fusion processing, and providing time-unified flight state data for the construction of input vectors.

[0071] In step S130, the variant state information and the flight state information are processed by anti-aliasing filtering and sensor fusion algorithm to obtain the input vector.

[0072] Understandably, to ensure the accuracy of the input vector, this application first applies an anti-aliasing low-pass filter to the raw sensor data to suppress high-frequency noise, such as a 6th-order Butterworth filter with a cutoff frequency 0.2 times the sampling frequency. Subsequently, sensor fusion algorithms, such as complementary filtering (combining fast response with low-frequency stability) or extended Kalman filtering (based on real-time estimation using aircraft dynamics and measurement models), are employed to achieve denoising and unification of multi-source data. The final output is a unified configuration-state input vector for use in aerodynamic center prediction and control law calculation.

[0073] The core function of anti-aliasing low-pass filtering is to filter high-frequency noise and interference signals in the raw data, preventing data distortion caused by high-frequency components and ensuring data smoothness. Sensor fusion algorithms, on the other hand, integrate heterogeneous data from multiple sources to compensate for the measurement limitations of a single sensor and improve data redundancy and reliability. The input vector formed after processing by both can comprehensively and accurately integrate the current variant state and flight state of the aircraft, providing high-quality data support for subsequent key steps such as aerodynamic center prediction and target center of gravity calculation, ensuring the accurate implementation of control strategies.

[0074] Furthermore, the input vector is:

[0075]

[0076] in, For the input vector, For wing sweep angle, For aspect ratio, For the flap deflection angle, For the angle of attack, For flight speed, For height, The pitch angle, For lateral acceleration, This is the longitudinal acceleration.

[0077] In step S200, the initial aerodynamic center position is calculated using the aerodynamic center prediction function based on the input vector, and the aerodynamic center position is determined based on the change in the aerodynamic center position.

[0078] It should be noted that the aerodynamic center is the point of application of the resultant aerodynamic forces of the aircraft, and its position changes dynamically with the variant state and flight state. The relative position of the aerodynamic center and the center of gravity directly determines the longitudinal static stability of the aircraft. Therefore, this step, which calculates and determines the position of the aerodynamic center by input vector, is the core link between state perception and center of gravity adjustment. It provides key aerodynamic parameters for the subsequent accurate calculation of the target center of gravity position, and directly affects the effectiveness of active center of gravity adjustment and flight stability.

[0079] In one embodiment, such as Figure 3 As shown, step S200 may include the following sub-steps:

[0080] In step S210, the aerodynamic center prediction function is obtained by using a pre-established wind tunnel test database, CDF simulation data, or online modeling.

[0081] It should be noted that the three methods for obtaining aerodynamic center prediction functions each have their advantages and can complement each other: wind tunnel test databases, based on measured data from physical models, possess the highest physical realism and serve as the fundamental data source for prediction functions; computational fluid dynamics (CFD) simulation data can cover a wider range of operating conditions, such as extreme speeds and angles of attack combinations, compensating for the high cost and limited operating conditions of wind tunnel testing; online modeling can dynamically correct the prediction function using real-time data during flight, adapting to performance degradation or sudden changes in aerodynamic characteristics during long-term aircraft use, such as component deformation. In practical applications, these three methods are often combined to ensure the accuracy and robustness of the prediction function across the entire flight envelope, meeting the aerodynamic center prediction requirements under different variant scenarios.

[0082] In step S220, the input vector is substituted into the aerodynamic center prediction function to calculate the initial aerodynamic center position.

[0083] It should be noted that the input vector covers all key parameters of the aircraft's variant state and flight state. Substituting it into the prediction function can realize the calculation of the aerodynamic center under the coupling of multiple factors, avoiding the deviation caused by the prediction of a single parameter.

[0084] In step S230, the change in the aerodynamic center position is limited by a saturation function to determine the aerodynamic center position.

[0085] Understandably, the core function of the saturation function is to impose physical boundaries and safety threshold constraints on the changes in the aerodynamic center position. On one hand, the changes in the aerodynamic center of an aircraft have physical limits; predictions exceeding these limits have no practical physical meaning. On the other hand, sensor noise and instantaneous extreme conditions can cause abnormal jumps in the changes in the aerodynamic center position. Directly using these jumps would lead to erroneous center-of-gravity adjustment commands, or even attitude instability. By limiting the amplitude using the saturation function, the final output aerodynamic center position can be ensured to be within a safe and reasonable range, significantly improving parameter reliability and providing a stable and safe input basis for subsequent target center-of-gravity calculations and actuator adjustments.

[0086] Optionally, the saturation function is:

[0087]

[0088] in, This represents the change in the position of the aerodynamic center. The location of the aerodynamic center. This represents the maximum change in the position of the aerodynamic center.

[0089] Understandably, this saturation function ensures that the change in aerodynamic center position conforms to the physical limits of the aircraft's aerodynamic characteristics by limiting the change in aerodynamic center position to the maximum range of aerodynamic center position change. At the same time, it can effectively avoid abnormal changes caused by sensor noise and instantaneous extreme conditions, and prevent subsequent center of gravity adjustment commands from jumping or exceeding limits. This ensures the stability and safety of the active center of gravity adjustment system, so that the final output aerodynamic center position is always in a reliable and controllable range, providing a physically logical input basis for target center of gravity calculation and actuator actions.

[0090] In step S300, the target center of gravity position is calculated based on the longitudinal static stability using the aircraft's average aerodynamic chord length and the aerodynamic center position, and the target center of gravity position adjustment amount is obtained.

[0091] Understandably, this step transforms aerodynamic characteristics requirements into center of gravity control targets. The average aerodynamic chord of the aircraft serves as a standardized benchmark, eliminating the impact of dimensional differences under different aircraft types or configurations on parameter calculations. Longitudinal static stability is a key indicator for measuring flight stability, and its value directly determines the reasonable distance between the center of gravity and the aerodynamic center, directly ensuring the balance between flight stability and handling quality during variant processes.

[0092] In one embodiment, such as Figure 4 As shown, step S300 may include the following sub-steps:

[0093] In step S310, the desired longitudinal static stability is determined based on the flight mission scenario.

[0094] It should be noted that the expected longitudinal static stability is determined based on flight mission requirements, the aerodynamic characteristic boundaries of the aircraft, and aviation safety standards.

[0095] First, based on the flight mission scenario, i.e., the different requirements for aircraft stability and maneuverability balance for different missions, a preliminary value for the desired longitudinal static stability is determined:

[0096] Cruise and long-endurance flight must prioritize attitude stability, with a target longitudinal static stability of 0.05 to 0.15 (based on the mean aerodynamic chord), meeting the "high stability margin" requirement for longitudinal static stability. High-maneuverability flight requires reduced stability to improve handling agility, with a target longitudinal static stability of 0.02 to 0.05, and even allowing for a small range of "weak stability". During takeoff and landing, stability and disturbance rejection capabilities must be considered, with a target longitudinal static stability of 0.08 to 0.12, higher than the cruise value, to cope with low-altitude airflow disturbances.

[0097] Secondly, it is necessary to combine the aerodynamic characteristics boundary of the aircraft to lock the feasible range of stability. First, the maximum range of change of the aerodynamic center within the entire flight envelope is determined by wind tunnel test database and CFD expected longitudinal static stability simulation data. Then, combined with the maximum stroke of the center of gravity adjustment actuator, the feasible range of the relative distance between the aerodynamic center and the center of gravity is calculated. In turn, the physical upper and lower limits of the expected static stability are deduced to avoid exceeding the adjustment capability and causing stability to run out of control.

[0098] Finally, the final values ​​are determined by verification according to aviation safety standards. They must meet industry standards such as the FAA's "Aircraft Flight Quality Standards" and the national military standard "Military Aircraft Flight Quality Requirements" to ensure a safety redundancy of 15% to 20% under extreme disturbances. At the same time, the actual flight data of similar aircraft models are referenced, and fine-tuning is performed based on the aircraft's own aerodynamic differences to ensure the engineering feasibility of the preset values. Finally, the values ​​must be verified by reverse verification using the target center of gravity position formula to ensure that they match the center of gravity adjustment capability.

[0099] In step S320, the target center of gravity position is obtained by using the target center of gravity position formula based on the aircraft's average aerodynamic chord length, the aerodynamic center position, and the desired longitudinal static stability margin.

[0100] It should be noted that this step uses the aerodynamic center position as a reference, and calculates the reasonable distance that the center of gravity should maintain from the aerodynamic center by multiplying the desired longitudinal static stability by the average aerodynamic chord length, thereby determining the specific coordinates of the center of gravity. The introduction of the average aerodynamic chord length avoids calculation deviations caused by size differences, ensuring the consistency of the calculation logic for the target center of gravity position under different configurations; at the same time, its calculation results provide basic target values ​​for conventional flight conditions.

[0101] Optionally, the target center of gravity position formula is determined based on the longitudinal static stability formula, wherein:

[0102] The formula for longitudinal static stability is:

[0103]

[0104] in, For longitudinal static stability, The location of the aerodynamic center. The current center of gravity position, The mean aerodynamic chord of the aircraft.

[0105] The formula for the target centroid position is:

[0106]

[0107] in, The target center of gravity position, This represents the desired longitudinal static stability.

[0108] Understandably, the aerodynamic center position determined in step S200 is obtained based on the longitudinal static stability formula.

[0109] In step S330, when there are requirements for the short-period damping ratio and the natural frequency, the target centroid position is obtained through a multi-objective optimization problem.

[0110] It should be noted that this step makes up for the limitations of relying solely on longitudinal static stability calculations. The short-cycle damping ratio determines the smoothness of the aircraft's attitude response. If the damping ratio is too low, it can easily cause attitude oscillations. The short-cycle natural frequency determines the response speed. If the frequency is too high, it can easily lead to sensitive control. Both factors together affect the flight control feel and safety.

[0111] Optionally, the multi-objective optimization problem is:

[0112]

[0113] in, As the first weighting coefficient, This is the second weighting coefficient. The third weighting coefficient, For short-cycle damping ratio, This is a reference value for the short-cycle damping ratio. It is a short-period natural frequency. This is a reference value for the short-period natural frequency.

[0114] It should be noted that in the multi-objective optimization problem, the first, second, and third weighting coefficients can be dynamically adjusted according to the flight phase. By balancing stability and handling characteristics, the target center of gravity position is output to better meet the needs of complex missions, reflecting the flexibility and comprehensiveness of the control strategy.

[0115] In step S340, the target center of gravity position adjustment amount is obtained based on the target center of gravity position and the current center of gravity position.

[0116] It should be noted that the adjustment amount of the target center of gravity directly determines the direction and distance of movement of the actuator. Factors such as aircraft fuel consumption and slight load shifts may cause dynamic changes in the current center of gravity. Therefore, the latest value must be obtained through real-time data collection or model estimation to avoid deviations in the adjustment amount due to lag in the current center of gravity data. Simultaneously, the adjustment amount must match the physical travel of the actuator to ensure the safety and reliability of subsequent execution processes.

[0117] In step S400, the center of gravity of the aircraft is adjusted to the target center of gravity position by means of the center of gravity adjustment actuator.

[0118] It should be noted that the center of gravity adjustment actuator can adopt the specific structure of the center of gravity adjustment actuator described in, for example, the "Design of Double-Rail Forward-Sweeping Mechanism for Aircraft Wings" in the Journal of Aeronautics, DOI: CNKI:SUN:HKXB.0.2012-11-009.

[0119] In one embodiment, the center of gravity adjustment actuator is controlled by a feedforward PID composite control, and the mechanism thrust formula is:

[0120]

[0121] in, For institutional thrust, As a proportion, For differential, For feedforward gain, This is the error in the position of the center of gravity. , This represents the rate of change of the center of gravity position error.

[0122] It should be noted that feedforward PID composite control combines the advantages of feedforward compensation and PID feedback regulation; the feedforward term... By introducing compensation for the rate of change of the target center of gravity in advance, the dynamic adjustment needs of the center of gravity can be responded to quickly; proportional term To achieve instant correction of the center of gravity position error, the differential term This suppresses overshoot and oscillations during the adjustment process. This control architecture can simultaneously ensure adjustment accuracy and dynamic response speed in scenarios where the center of gravity of a variant aircraft changes rapidly. For example, when the aerodynamic center shifts sharply backward due to large-angle wing sweep, this control law can quickly drive the center of gravity adjustment mechanism to avoid large fluctuations in flight stability.

[0123] In one embodiment, the step of adjusting the aircraft's center of gravity to the target center of gravity position via the center of gravity adjustment actuator further includes:

[0124] During the adjustment process of the center of gravity adjustment actuator, the flight control system corrects the pitch moment compensation term based on the real-time position of the slider and the predicted aerodynamic center; the calculation formula for the pitch moment compensation term is as follows:

[0125]

[0126] in, For pitch moment compensation, As the reference aerodynamic torque, For quality, It is the acceleration due to gravity. Adjustment amount for the target center of gravity position. It is the pitch angle.

[0127] It should be noted that during center of gravity adjustment, the change in the target center of gravity position will trigger an additional pitch moment. If not compensated, this can easily lead to pitch instability of the aircraft. The core function of the pitch moment compensation term is to correct the torque deviation caused by the adjustment of the center of gravity and the change in pitch angle in real time. The reference aerodynamic moment is the torque corresponding to the initial center of gravity matching the aerodynamic center, quantifying the change in gravitational torque caused by the shift of the center of gravity. By dynamically correcting this compensation term, the flight control system can maintain pitch stability while adjusting the center of gravity. For example, when the center of gravity shifts significantly backward, the compensation moment can be increased to prevent the aircraft from pitching down, ensuring handling stability during the transformation process.

[0128] In one embodiment, the step of adjusting the aircraft's center of gravity to the target center of gravity position via the center of gravity adjustment actuator further includes:

[0129] Throughout the center of gravity adjustment process, the slider position, speed, and drive current are monitored, and the slider is stopped when any of these exceed the preset range.

[0130] It should be noted that the continuous monitoring of the slider position, speed, and drive current is a safety redundancy design: exceeding the slider position limits can lead to mechanical damage to the mechanism, such as structural deformation caused by exceeding the slide rail travel; abnormal speed, such as sudden speed increases / decreases due to jamming, or drive current overload can lead to actuator malfunctions, such as motor stall. The preset range must be set in conjunction with the physical performance parameters of the actuator, such as the maximum slider travel, the rated motor current, and the safe speed threshold. If any parameter exceeds the range, the slider will stop immediately, which can effectively avoid damage to the center of gravity adjustment mechanism and prevent loss of flight attitude control caused by abnormal adjustment. This is a key measure to ensure the robustness of the center of gravity adjustment system of the variator aircraft.

[0131] Furthermore, specific implementation examples are provided for different scenarios:

[0132] Implementation 1: In response to the configuration adjustment process of an advanced variable-sweep wing aircraft, especially the problem of decreased longitudinal static stability caused by a significant rearward shift of the aerodynamic center of gravity during rapid switching from a low sweep angle to a high sweep angle at high speeds, the active center of gravity adjustment control method for advanced aircraft variant processes proposed in this application was used for verification.

[0133] This scheme utilizes configuration status sensors and flight control systems to predict the aerodynamic center of gravity, calculates the target's center of gravity position based on stability indicators, and completes precise adjustment within seconds using high-speed sliding rail mass blocks. This achieves longitudinal stability maintenance and attitude disturbance suppression throughout the configuration change process, significantly improving flight quality and safety margin during high-speed configuration switching.

[0134] Step S100: Configuration and flight status acquisition;

[0135] A high-precision photoelectric encoder is installed on the wing sweep adjustment mechanism of this fighter jet to measure the wing sweep angle. The measurement accuracy is During flight, the sweep angle was adjusted from 30° to 60°, and the configuration change time was 3.0s.

[0136] Meanwhile, the flight control system collects angle of attack data via the integrated avionics bus. Vacuum speed Flight altitude Pitch angle and longitudinal acceleration .

[0137] These data, after being synchronously processed at a sampling frequency of 100Hz, form a configuration-state input vector:

[0138] .

[0139] Step S200: Aerodynamic center prediction;

[0140] An aerodynamic center prediction model was established by fusing wind tunnel tests, CFD simulations, and real flight data. The instantaneous position change of the aerodynamic center during the sweep angle variation is calculated. The prediction results show that when... When the angle increases from 30° to 60°, the aerodynamic center The distance was moved from 15.20m to 15.65m, a shift of 0.45m relative to the aircraft's reference plane. To suppress the influence of sensor noise, the prediction module employed an extended Kalman filter, with process noise covariance... Measure noise covariance This ensures that the prediction curve is smooth and free of spikes or jitter.

[0141] Step S300: Calculate the target center of gravity position;

[0142] Mean aerodynamic chord of aircraft Desired longitudinal static stability According to the formula:

[0143] ;

[0144] .

[0145] Step S400: Mass slider adjustment is performed;

[0146] The actuator is an electric lead screw driven slide rail type mass slider, the slider mass is 200kg, and the maximum stroke is... Maximum linear velocity Rated thrust 5kN.

[0147] The controller employs a feedforward + PID composite control:

[0148] .

[0149] To reduce impact load, velocity planning employs S-curve acceleration limits, with a maximum acceleration of 1.5 m / s² and a maximum jerk. Actual execution time Position error ±0.4mm.

[0150] Step S500: Flight control coordination compensation;

[0151] Upon receiving feedback on the slider position, the flight control computer immediately adjusts the pitch moment compensation.

[0152] .

[0153] Step S600: Safety protection;

[0154] The slider position, speed, and drive current were adjusted throughout the entire process, and no over-limit or abnormal alarms occurred; the limit switches and software protection were both effective, ensuring flight safety.

[0155] Second, for mission switching scenarios of large, long-endurance variable aspect ratio UAVs, when rapidly shrinking from a high aspect ratio flight configuration to a low aspect ratio high-speed penetration configuration, the change in stability margin caused by the forward shift of the aerodynamic center is compensated in real time by the active center of gravity adjustment control method for advanced aircraft variant processes proposed in this application.

[0156] Before configuration changes, the system predicts the change in aerodynamic center, calculates the required rearward shift of the center of gravity, and drives a high-speed responsive sliding mass slider to complete the adjustment. At the same time, the flight control system coordinates to correct elevator trim, ensuring smooth attitude changes and stable flight trajectory throughout the process, thereby maintaining stable handling and stability during mission transitions across the large flight envelope.

[0157] Step S100: Configuration and flight status acquisition;

[0158] The drone's wing extension mechanism is equipped with a high-precision linear displacement sensor, which measures the aspect ratio change range from 16 to 10, and the extension process takes 4.0 seconds.

[0159] Flight control system collects angle of attack ,speed ,high Pitch angle Longitudinal acceleration The data sampling rate is 80Hz.

[0160] Step S200: Aerodynamic center prediction;

[0161] By accessing the aspect ratio-aerodynamic center database and combining it with flight correction factors, the aerodynamic center is predicted from... Move forward The change is +0.28m.

[0162] Unscented Kalman filtering was used to smooth the data during the prediction process, with the process noise variance set to 0.001 and the measurement noise variance set to 0.003, to ensure that the output curve remained stable during dynamic changes in the aspect ratio.

[0163] Step S300: Calculate the target center of gravity position;

[0164] Mean aerodynamic chord length Desired longitudinal static stability Calculate the target's center of gravity position:

[0165] ;

[0166] .

[0167] Step S400: Mass slider adjustment is performed;

[0168] The slider weighs 150kg, has a maximum stroke of ±0.4m, and the drive system is a brushless servo motor + ball screw mechanism with a rated thrust of 3kN.

[0169] Position closed-loop PID control is adopted, combined with five-stage speed planning (acceleration-constant speed-deceleration-buffering-stop) to reduce mechanical shock;

[0170] Adjusting time Position control accuracy is ±0.5mm.

[0171] Step S500: Flight control coordination compensation;

[0172] The flight control system corrects the elevator trim angle based on the slider position and increases the damping coefficient by 15% in the short-period channel to control pitch attitude fluctuations within ±0.4° and altitude fluctuations ≤±2m, thus maintaining a smooth mission switching process.

[0173] Step S600: Safety protection;

[0174] The slider control system is equipped with dual limit protection (hardware limit + software limit) and current overload protection, and no abnormalities occurred during the entire adjustment process.

[0175] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the appended claims.

Claims

1. A method for active center of gravity adjustment control during advanced aircraft variant processes, characterized in that, include: The variant state information of the aircraft is collected in real time, and the flight state information is acquired simultaneously to obtain the input vector; wherein, the variant state information includes wing sweep angle, aspect ratio and flap deflection angle, and the flight state information includes angle of attack, flight speed, altitude, pitch angle and acceleration; Based on the input vector, the initial aerodynamic center position is calculated using the aerodynamic center prediction function, and the aerodynamic center position is determined based on the change in the aerodynamic center position. The target center of gravity position is calculated based on the longitudinal static stability using the aircraft's average aerodynamic chord length and the aerodynamic center position, and the target center of gravity position adjustment amount is obtained. The center of gravity of the aircraft is adjusted to the target center of gravity position by the center of gravity adjustment actuator.

2. The active center of gravity adjustment control method for advanced aircraft variant processes according to claim 1, characterized in that, The step of acquiring real-time variant state information of the aircraft and synchronously obtaining flight state information to obtain an input vector includes: Configuration status sensors are installed in the variable configuration parts of the aircraft to collect configuration parameters in real time; wherein, the variable configuration parts include the wing rotation pivot, the tail fin mounting point and the variable aspect ratio mechanism, and the configuration status sensors include photoelectric encoders, laser displacement sensors and angle sensors; Flight status parameters are obtained through the aircraft's flight control system; The variant state information and the flight state information are processed by anti-aliasing filtering and sensor fusion algorithms to obtain the input vector.

3. The active center of gravity adjustment control method for advanced aircraft variant processes according to claim 2, characterized in that, The input vector is: in, For the input vector, For wing sweep angle, For aspect ratio, For the flap deflection angle, For the angle of attack, For flight speed, For height, The pitch angle, For lateral acceleration, This is the longitudinal acceleration.

4. The active center of gravity adjustment control method for advanced aircraft variant processes according to claim 1, characterized in that, The step of calculating the change in aerodynamic center position based on the input vector using the aerodynamic center prediction function includes: The aerodynamic center prediction function is obtained by using a pre-established wind tunnel test database, CDF simulation data, or online modeling. Substitute the input vector into the aerodynamic center prediction function to calculate the initial aerodynamic center position; The aerodynamic center position is determined by limiting the change in the position of the aerodynamic center using a saturation function.

5. The active center of gravity adjustment control method for advanced aircraft variant processes according to claim 4, characterized in that, The saturation function is: in, This represents the change in the position of the aerodynamic center. The location of the aerodynamic center. This represents the maximum change in the position of the aerodynamic center.

6. The active center of gravity adjustment control method for advanced aircraft variant processes according to claim 1, characterized in that, The step of calculating the target center of gravity position based on the longitudinal static stability using the average aerodynamic chord length of the aircraft and the aerodynamic center position, and obtaining the target center of gravity position adjustment amount, includes: Determine the desired longitudinal static stability based on the flight mission scenario; Based on the aircraft's average aerodynamic chord length, the aerodynamic center position, and the desired longitudinal static stability margin, the target center of gravity position is obtained using the target center of gravity position formula. When there are requirements for short-period damping ratio and natural frequency, the target centroid position is obtained through a multi-objective optimization problem; The target center of gravity position adjustment amount is obtained based on the target center of gravity position and the current center of gravity position.

7. The active center of gravity adjustment control method for advanced aircraft variant processes according to claim 6, characterized in that, The formula for the target centroid position is: in, The target center of gravity position, To achieve the desired longitudinal static stability, The mean aerodynamic chord of the aircraft; The multi-objective optimization problem is: in, As the first weighting coefficient, This is the second weighting coefficient. The third weighting coefficient, For short-cycle damping ratio, This is a reference value for the short-cycle damping ratio. It is a short-period natural frequency. This is a reference value for the short-period natural frequency. For longitudinal static stability.

8. The active center of gravity adjustment control method for advanced aircraft variant processes according to claim 1, characterized in that, The center of gravity adjustment actuator is controlled by a feedforward PID composite control, and the thrust formula of the mechanism is: in, For institutional thrust, As a proportion, For differential, For feedforward gain, This is the error in the position of the center of gravity. , This represents the rate of change of the center of gravity position error.

9. The active center of gravity adjustment control method for advanced aircraft variant processes according to claim 1, characterized in that, The step of adjusting the aircraft's center of gravity to the target center of gravity position via the center of gravity adjustment actuator further includes: During the adjustment process of the center of gravity adjustment actuator, the flight control system corrects the pitch moment compensation term based on the real-time position of the slider and the predicted aerodynamic center; the calculation formula for the pitch moment compensation term is as follows: in, For pitch moment compensation, As the reference aerodynamic torque, For quality, It is the acceleration due to gravity. Adjustment amount for the target center of gravity position. It is the pitch angle.

10. The active center of gravity adjustment control method for advanced aircraft variant processes according to claim 1, characterized in that, The step of adjusting the aircraft's center of gravity to the target center of gravity position via the center of gravity adjustment actuator further includes: Throughout the center of gravity adjustment process, the slider position, speed, and drive current are monitored, and the slider is stopped when any of these exceed the preset range.

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