Aircraft aerodynamic parameter identification method and system

Abstract

The present invention provides an aircraft aerodynamic parameter identification method and system, relating to the field of aircraft control technology, wherein the method comprises the following steps: collecting aircraft response data; constructing a closed-loop adaptive excitation signal generator, and using the closed-loop adaptive excitation signal generator to identify the aircraft response data to obtain a corresponding excitation signal; and outputting the excitation signal to the aircraft. The present invention utilizes the closed-loop adaptive excitation signal generator to automatically match the actual flight conditions and movement performance of the aircraft, iteratively generates excitation actions that meet the requirements of the aerodynamic parameter identification data, or tries a variety of different excitation signals, which is beneficial to improving the efficiency of aerodynamic parameter identification tests and ensuring test safety.

Description

Technical Field

[0001] The present invention relates to the field of aircraft control technology, and more particularly to an aircraft aerodynamic parameter identification method and system. Background Art

[0002] At present, aircraft aerodynamic parameter identification is of great significance to aircraft development, design, and test optimization: (1) Through the identification of test data in the development stage, the parameters of the theoretical or wind tunnel model can be checked and corrected, thereby improving the design of the control law and providing the most accurate model basis for advanced control methods; (2) Through online identification, adaptive control can be achieved, or faults can be identified online to achieve fault-tolerant reconstructive control; (3) Through post-processing of flight data and system identification, flight quality appraisal can be carried out.

[0003] However, existing aircraft aerodynamic parameter identification methods suffer from the following major problems: (a) Existing aerodynamic parameter identification techniques rely on a relatively simple selection of excitation signals, relying on aerodynamic data obtained from ground wind tunnel tests and CFD simulations to select the excitation signal type, frequency, and amplitude. In actual flight tests, due to the complex flight conditions and differences between aircraft dynamics and design, the selected excitation signal may not be able to stimulate the aircraft's state variables to produce the required short-period motion modes. As a result, the obtained aircraft response data does not meet the requirements of aerodynamic parameter identification, resulting in test failure and a waste of manpower, material, financial, and time resources. The aircraft may even be affected by the unreasonable excitation signal and become unstable and crash. (b) Existing aerodynamic parameter identification techniques often run on the flight control computer core along with conventional processes such as control law algorithms and sensor data acquisition and processing. This leads to shortcomings such as insufficient computing power, inability to isolate faults, and system complexity, posing risks to aerodynamic parameter identification results and flight safety. The non-modular design also makes subsequent algorithm maintenance and upgrades difficult, making it difficult to adapt to different aircraft platforms to expand the applicable scope of aerodynamic parameter identification techniques.

[0004] Therefore, how to provide an aircraft aerodynamic parameter identification method that can solve the above problems is an issue that those skilled in the art urgently need to solve. Summary of the Invention

[0005] In view of this, the present invention provides an aircraft aerodynamic parameter identification method and system, which uses a closed-loop adaptive excitation signal generator to automatically match the aircraft's actual flight conditions and motion performance, iteratively generates excitation actions that meet the aerodynamic parameter identification data requirements or tries a variety of different excitation signals, which is conducive to improving the efficiency of aerodynamic parameter identification tests and ensuring test safety.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for identifying aircraft aerodynamic parameters comprises the following steps:

[0008] Collect aircraft response data;

[0009] Constructing a closed-loop adaptive excitation signal generator, and using the closed-loop adaptive excitation signal generator to identify the aircraft response data to obtain a corresponding excitation signal;

[0010] The excitation signal is output to the aircraft.

[0011] Preferably, the specific process of constructing a closed-loop adaptive excitation signal generator includes:

[0012] The closed-loop adaptive excitation signal generator includes: a preprocessing module, an auxiliary analysis module, a judgment module, and an adjustment module.

[0013] Preferably, the closed-loop adaptive excitation signal generator further includes: a signal excitation module.

[0014] Preferably, the specific process of using the closed-loop adaptive excitation signal generator to identify the aircraft response data includes:

[0015] preprocessing the aircraft response data by the preprocessing module;

[0016] Performing auxiliary analysis on the pre-processed aircraft response data by the auxiliary analysis module to obtain corresponding auxiliary analysis results;

[0017] Determining, by the judgment module, whether the auxiliary analysis result can excite the short-period motion mode of the aircraft, and obtaining a corresponding judgment result;

[0018] The adjustment module determines whether the current excitation signal needs to be adjusted according to the judgment result.

[0019] Preferably, the specific process of using the closed-loop adaptive excitation signal generator to identify the aircraft response data further includes:

[0020] When the current excitation signal needs to be adjusted, the signal excitation module processes the current excitation signal to obtain a corresponding new excitation signal, and outputs the new excitation signal to the aircraft.

[0021] Preferably, the specific process of determining whether the current excitation signal needs to be adjusted according to the judgment result by the adjustment module includes:

[0022] When the auxiliary analysis result cannot excite the short-period motion mode of the aircraft, determining an adjustment amount of the current excitation signal through an adaptive signal adjustment algorithm, and adjusting the current excitation signal according to the adjustment amount to obtain a new excitation signal until the new excitation signal can excite the short-period motion mode of the aircraft;

[0023] The new excitation signal is output to the aircraft.

[0024] Preferably, the specific process of determining whether the current excitation signal needs to be adjusted according to the judgment result by the adjustment module further includes:

[0025] If the new excitation signal still fails to cause the aircraft to excite the short-period motion mode of the aircraft after several iterations,

[0026] Selecting an excitation signal from a preset excitation signal library and superimposing the current excitation signal and the excitation signal to generate a new excitation signal;

[0027] The new excitation signal is converted into time domain and then output to the aircraft.

[0028] Preferably, the specific process of determining the adjustment amount of the current excitation signal by the adaptive signal adjustment algorithm includes:

[0029] defining a cost function, and quantifying an adjustment amount of the current excitation signal using the cost function, wherein the adjustment amount is any one or more of the frequency and amplitude of the current excitation signal;

[0030] Calculating gradient information of the cost function relative to the adjustment amount of the current excitation signal;

[0031] The adjustment amount of the current excitation signal is obtained by using the gradient information and a gradient descent method.

[0032] The present invention also provides an aircraft aerodynamic parameter identification system, comprising:

[0033] Acquisition module, used to collect aircraft response data;

[0034] a processing module, configured to construct a closed-loop adaptive excitation signal generator, and use the closed-loop adaptive excitation signal generator to identify the aircraft response data to obtain a corresponding excitation signal;

[0035] The output module is used to output the excitation signal to the aircraft.

[0036] As can be seen from the above technical solutions, compared with the prior art, the present invention provides a method and system for aircraft aerodynamic parameter identification. This system utilizes a closed-loop adaptive excitation signal generator to automatically match the aircraft's actual flight conditions and motion performance, iteratively generating excitation actions that meet the aerodynamic parameter identification data requirements or attempting a variety of different excitation signals. This helps improve the efficiency of aerodynamic parameter identification tests and ensures test safety. Furthermore, this identification method is deployed on a high-performance multi-core processor and a time-sharing and partitioned modular system, enabling the core-by-core completion of aircraft sensor data acquisition and processing, flight control law calculations, closed-loop excitation signal generation, and aerodynamic parameter identification calculations, achieving intelligent multi-core processing task allocation and load balancing, fault isolation, and rapid deployment. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0038] Figure 1 An overall flow chart of an aircraft aerodynamic parameter identification method provided by the present invention;

[0039] Figure 2 This is a structural principle block diagram of an aircraft aerodynamic parameter identification system provided by the present invention. DETAILED DESCRIPTION

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0041] See also Figure 1 As shown, an embodiment of the present invention discloses a method for identifying aircraft aerodynamic parameters, comprising the following steps:

[0042] Collect aircraft response data, where the aircraft response data can be collected from the flight data after excitation from the onboard sensors through a variety of different protocols such as CAN bus, 232, 422, Ethernet, etc., mainly including the aircraft relative to the airflow speed V, the aircraft roll angle φ, the aircraft pitch angle θ, the aircraft yaw angle ψ, the aircraft angle of attack α, the aircraft sideslip angle β, and the three-axis component of the aircraft relative to the ground speed in the ground inertial coordinate system V ex 、V ey 、V ez, the three-axis components a of the aircraft acceleration in the body coordinate system x 、a y 、a z , the three-axis components p, q, and r of the aircraft's angular velocity in the body coordinate system. The above physical quantities are necessary inputs for the aerodynamic parameter identification algorithm;

[0043] Construct a closed-loop adaptive excitation signal generator, and use it to identify the aircraft response data to obtain the corresponding excitation signal;

[0044] Output excitation signal to the aircraft.

[0045] In a specific embodiment, the specific process of constructing a closed-loop adaptive excitation signal generator includes:

[0046] The closed-loop adaptive excitation signal generator includes: a preprocessing module, an auxiliary analysis module, a judgment module, and an adjustment module.

[0047] In a specific embodiment, the closed-loop adaptive excitation signal generator further includes: a signal excitation module.

[0048] In a specific embodiment, the specific process of identifying aircraft response data using a closed-loop adaptive excitation signal generator includes:

[0049] Preprocessing the aircraft response data through the preprocessing module;

[0050] Perform auxiliary analysis on the pre-processed aircraft response data through the auxiliary analysis module to obtain corresponding auxiliary analysis results;

[0051] Determine through the judgment module whether the auxiliary analysis results can stimulate the short-period motion mode of the aircraft and obtain the corresponding judgment results;

[0052] The adjustment module determines whether the current excitation signal needs to be adjusted according to the judgment result.

[0053] In a specific embodiment, the specific process of identifying the aircraft response data using the closed-loop adaptive excitation signal generator further includes:

[0054] When the current excitation signal needs to be adjusted, the signal excitation module processes the current excitation signal to obtain a corresponding new excitation signal, and outputs the new excitation signal to the aircraft.

[0055] In a specific embodiment, the specific process of determining whether the current excitation signal needs to be adjusted according to the judgment result by the adjustment module includes:

[0056] When the auxiliary analysis results cannot excite the aircraft's short-period motion mode, the adaptive signal adjustment algorithm is used to determine the adjustment amount of the current excitation signal, and the current excitation signal is adjusted according to the adjustment amount to obtain a new excitation signal until the new excitation signal can excite the aircraft's short-period motion mode.

[0057] Output the new excitation signal to the aircraft.

[0058] In a specific embodiment, the specific process of determining whether the current excitation signal needs to be adjusted according to the judgment result by the adjustment module further includes:

[0059] If the new excitation signal still fails to make the aircraft excite the short-period motion mode after several iterations,

[0060] Generate a new excitation signal by selecting an excitation signal from a preset excitation signal library and superimposing the current excitation signal and the excitation signal. The excitation signal library includes signals such as 3211, sine, square wave, and sweep frequency.

[0061] The new excitation signal is converted into time domain and then output to the aircraft.

[0062] In a specific embodiment, the specific process of determining the adjustment amount of the current excitation signal by the adaptive signal adjustment algorithm includes:

[0063] A cost function is defined, and an adjustment amount of the current excitation signal is quantified by the cost function, wherein the adjustment amount is any one or more of the frequency and amplitude of the current excitation signal;

[0064] Calculate the gradient information of the cost function relative to the adjustment amount of the current excitation signal;

[0065] The adjustment amount of the current excitation signal is obtained using the gradient information and the gradient descent method.

[0066] Specifically, the preprocessing module may include a filtering unit and a Fourier transform unit. The filtering unit may include a low-pass filter and a Kalman filter processed in sequence. The Fourier transform unit completes the conversion from the time domain to the frequency domain. After the Fourier transform, the frequency spectrum of the motion state of each physical quantity in the aircraft excitation response data can be obtained. Since the short-period mode of the aircraft is mainly reflected in the motion state of the aircraft angle of attack α and the pitch angular velocity q in the longitudinal motion, it is manifested as an oscillation characteristic with high frequency, short period and fast decay after being excited. Therefore, the motion frequency composition of the aircraft angle of attack α and the pitch angular velocity q can be analyzed through the frequency domain auxiliary analysis module, and compared with the short-period modal frequency obtained in the simulation control stability characteristic analysis, it is judged whether the excitation signal has excited the short-period motion mode of the aircraft.

[0067] If the frequency domain analysis results show that the aircraft excitation state conforms to the law of short-period modal motion, the parameter identification partition is notified to perform recursive least squares estimation on the filtered flight data through the parameter identification application combined with the linear small perturbation equations to obtain the aerodynamic parameter identification results. The results mainly include the derivative of the pitching moment coefficient with respect to the angle of attack Cmα, the derivative of the lift coefficient with respect to the angle of attack CLα, the derivative of the pitching moment coefficient with respect to the pitch angular velocity Cmq, the derivative of the lift coefficient with respect to the pitch angular velocity CLq, the derivative of the lift coefficient with respect to the elevator deflection CLδe, and the derivative of the pitching moment coefficient with respect to the elevator deflection Cmδe.

[0068] If the frequency domain analysis results show that the aircraft does not excite short-period modes under the current excitation signal, the excitation signal is processed through the excitation signal closed-loop generation application in the signal processing partition. The specific processing method is as follows Figure 1 As shown in the circular structure on the right: Based on the current excitation situation, the excitation signal change is calculated through an adaptive signal adjustment algorithm to adjust the period and amplitude of the excitation signal. Alternatively, different signals, including but not limited to 3211, sine signals, square wave signals, and swept frequency signals, can be reselected from the excitation library to generate the next excitation signal. After the signal is regenerated, the excitation signal fusion application in the control law partition is used to output a new excitation signal to the control surface, thereby controlling the aircraft to produce a new excitation action, and then returning to step one for data collection. Then, step two is entered for processing and judgment until the aircraft's excitation action meets the aerodynamic identification requirements, achieving the goal of adaptively matching the excitation signal to the current aircraft's flight conditions and actual performance, and efficiently and safely completing the collection of aerodynamic parameter identification data.

[0069] See also Figure 2 As shown, an embodiment of the present invention further provides a system using the aircraft aerodynamic parameter identification method of any of the above embodiments, comprising:

[0070] Acquisition module, used to collect aircraft response data;

[0071] A processing module is used to construct a closed-loop adaptive excitation signal generator, and use the closed-loop adaptive excitation signal generator to identify the aircraft response data to obtain a corresponding excitation signal;

[0072] The output module is used to output the excitation signal to the aircraft.

[0073] Specifically, the hardware used in the aforementioned system can run on an integrated modular avionics core processor, which uses the Freescale QorIQ T1042 as its core processing chip. This chip contains four e5500 cores, each with a DMIPS performance of 4200. It supports 32 / 64-bit modes, with four cores sharing a 256KB L3 cache. Each core has 32KB of L1 data / instruction cache and 256KB of L2 cache. It also supports a DDR3L / 4 memory controller, PCI-E 2.0, SATA 2.0, and USB 2.0 interfaces, and serial ports including UART, I2C, and SPI. It also has multiple 5GHz SerDes interfaces that can be used to configure other types of interfaces.

[0074] The operating system uses the vxWorks 6533.x multi-core version operating system that complies with the ARINC 653 specification, and uses hypervisor technology to provide partitioning functions in time and space to curb the spread of faults and effectively reduce SWaP (Space, Weight, and Power) and bill of materials.

[0075] The airborne bus adopts the FC-AE-1553 bus. This bus protocol uses Fibre Channel technology and defines a command / response bus with a transmission rate and functions far exceeding the MIL-STD-1553 bus.

[0076] The core processor based on the ARINC 653 Hypervisor architecture can provide the aircraft with strong computing power while maintaining low power consumption. Supported by the ARINC 653 architecture, it can implement sensor data acquisition and control quantity output, signal filtering and closed-loop signal generation, flight control law and excitation signal fusion, and parameter identification algorithms running on different CPU cores and partitions. This ensures the independent execution of multiple tasks without mutual influence, and ensures the smooth and accurate operation of the aerodynamic parameter identification algorithm based on the closed-loop adaptive excitation signal generator.

[0077] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0078] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for identifying aircraft aerodynamic parameters, characterized in that: The following steps are involved: Collect aircraft response data; Constructing a closed-loop adaptive excitation signal generator, and using the closed-loop adaptive excitation signal generator to identify the aircraft response data to obtain a corresponding excitation signal; outputting the excitation signal to the aircraft; The closed-loop adaptive excitation signal generator includes: a preprocessing module, an auxiliary analysis module, a judgment module, an adjustment module, and a signal excitation module; The specific process of using the closed-loop adaptive excitation signal generator to identify the aircraft response data includes: preprocessing the aircraft response data by the preprocessing module; Performing auxiliary analysis on the pre-processed aircraft response data by the auxiliary analysis module to obtain corresponding auxiliary analysis results; Determining, by the judgment module, whether the auxiliary analysis result can excite the short-period motion mode of the aircraft, and obtaining a corresponding judgment result; The adjustment module determines whether the current excitation signal needs to be adjusted according to the judgment result, and the specific process includes: When the auxiliary analysis result cannot excite the short-period motion mode of the aircraft, determining an adjustment amount of the current excitation signal through an adaptive signal adjustment algorithm, and adjusting the current excitation signal according to the adjustment amount to obtain a new excitation signal until the new excitation signal can excite the short-period motion mode of the aircraft; The new excitation signal is output to the aircraft.

2. The method for identifying aircraft aerodynamic parameters according to claim 1, characterized in that: The specific process of using the closed-loop adaptive excitation signal generator to identify the aircraft response data also includes: When the current excitation signal needs to be adjusted, the signal excitation module processes the current excitation signal to obtain a corresponding new excitation signal, and outputs the new excitation signal to the aircraft.

3. The method for identifying aircraft aerodynamic parameters according to claim 1, characterized in that: The specific process of determining whether the current excitation signal needs to be adjusted according to the judgment result by the adjustment module further includes: If the new excitation signal still fails to cause the aircraft to excite the short-period motion mode of the aircraft after several iterations, Selecting an excitation signal from a preset excitation signal library and superimposing the current excitation signal and the excitation signal to generate a new excitation signal; The new excitation signal is converted into time domain and then output to the aircraft.

4. The method for identifying aircraft aerodynamic parameters according to claim 1, characterized in that: The specific process of determining the adjustment amount of the current excitation signal through the adaptive signal adjustment algorithm includes: defining a cost function, and quantifying an adjustment amount of the current excitation signal using the cost function, wherein the adjustment amount is any one or more of the frequency and amplitude of the current excitation signal; Calculating gradient information of the cost function relative to the adjustment amount of the current excitation signal; The adjustment amount of the current excitation signal is obtained by using the gradient information and a gradient descent method.

5. A system using the aircraft aerodynamic parameter identification method according to any one of claims 1 to 4, characterized in that: include: Acquisition module, used to collect aircraft response data; a processing module, configured to construct a closed-loop adaptive excitation signal generator, and use the closed-loop adaptive excitation signal generator to identify the aircraft response data to obtain a corresponding excitation signal; The output module is used to output the excitation signal to the aircraft.

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