Airplane aerodynamic parameter identification method and system

Abstract

The invention provides an aircraft aerodynamic parameter identification method and system, and relates to the technical field of aircraft control, and the method comprises the following steps: collecting aircraft response data; constructing a closed-loop self-adaptive excitation signal generator, and identifying the airplane response data by using the closed-loop self-adaptive excitation signal generator to obtain a corresponding excitation signal; outputting the excitation signal to an aircraft; according to the invention, the closed-loop adaptive excitation signal generator is utilized to automatically match the actual flight condition and motion performance of the aircraft, and the excitation action meeting the pneumatic parameter identification data requirement or attempt of various different excitation signals is iteratively generated, so that the pneumatic parameter identification test efficiency is improved and the test safety is guaranteed.

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, so as to improve the design of the control law and provide 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, the existing aircraft aerodynamic parameter identification methods mainly have the following problems: (a) The selection of excitation signals in the existing aerodynamic parameter identification technology is relatively simple, relying on the 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 the differences between the aircraft dynamics performance and the design, the selected excitation signal may not be able to excite the aircraft state quantity to the required short-period motion mode. Therefore, the obtained aircraft response data does not meet the requirements of aerodynamic parameter identification, resulting in test failure, resulting in waste of manpower, material resources, financial resources, time and other costs, and even the aircraft may be affected by unreasonable excitation signals and become unstable and crash. (b) The existing aerodynamic parameter identification technology often runs on the core of the flight control computer together with conventional links such as control law algorithms, sensor data collection and processing, etc., which has the disadvantages of insufficient computing power, inability to isolate faults, and complex systems, which poses risks to the aerodynamic parameter identification effect and flight safety. The non-modular design also brings certain difficulties to the subsequent algorithm maintenance and upgrade, and is not conducive to adapting to different aircraft platforms to expand the applicable range of aerodynamic parameter identification technology.

[0004] Therefore, how to provide an aircraft aerodynamic parameter identification method that can solve the above problems is an issue that technical personnel in this field 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 utilizes a closed-loop adaptive excitation signal generator to automatically match the actual flight conditions and motion performance of the aircraft, iteratively generates excitation actions that meet the requirements of 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.

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

[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] Determine, by the judgment module, whether the auxiliary analysis result can excite the short-period motion mode of the aircraft, and obtain 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 also includes:

[0020] When the current excitation signal needs to be adjusted, the current excitation signal is processed by the signal excitation module to obtain a corresponding new excitation signal, and the new excitation signal is output 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, an adjustment amount of the current excitation signal is determined by an adaptive signal adjustment algorithm, 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 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 the adjustment amount of the current excitation signal by 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 the gradient descent method.

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

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

[0034] A processing module, 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;

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

[0036] Through the above technical solutions, it can be known that compared with the prior art, the present invention discloses a method and system for aircraft aerodynamic parameter identification, which uses a closed-loop adaptive excitation signal generator to automatically match the actual flight conditions and motion performance of the aircraft, iteratively generates excitation actions that meet the requirements of aerodynamic parameter identification data or tries a variety of different excitation signals, which is conducive to improving the efficiency of aerodynamic parameter identification tests and ensuring test safety. At the same time, the identification method is deployed on a high-performance multi-core processor and a time-sharing and partitioned modular system, which can complete aircraft sensor data acquisition and processing, flight control law calculation, excitation signal closed-loop generation, and aerodynamic parameter identification calculation by core, realizing 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 drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

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

[0039] Figure 2 The present invention provides a structural principle block diagram of an aircraft aerodynamic parameter identification system. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work 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 airborne 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 V of the aircraft relative to the ground speed in the ground inertial coordinate system 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 rotational 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 the closed-loop adaptive excitation signal generator 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 using the closed-loop adaptive excitation signal generator to identify the aircraft response data includes:

[0049] Preprocessing the aircraft response data through a 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 result can stimulate the short-period motion mode of the aircraft and obtain the corresponding judgment result;

[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 also includes:

[0054] When the current excitation signal needs to be adjusted, the current excitation signal is processed by the signal excitation module to obtain a corresponding new excitation signal, and the new excitation signal is output 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 result cannot excite the short-period motion mode of the aircraft, the adjustment amount of the current excitation signal is determined by the adaptive signal adjustment algorithm, 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 short-period motion mode of the aircraft;

[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 cannot cause the aircraft to excite the short-period motion mode after several iterations,

[0060] Select an excitation signal from a preset excitation signal library, and superimpose the current excitation signal and the excitation signal to generate a new 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 that are processed in sequence. The conversion from the time domain to the frequency domain is completed by the Fourier transform unit. 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 reflected 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 short-period modal motion law, the parameter identification partition is notified to perform recursive least squares estimation on the filtered flight data through parameter identification application in combination with the linear small perturbation equation group to obtain the aerodynamic parameter identification results. The results mainly include the derivative of the pitch 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 pitch 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 pitch 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: according to the current excitation situation, the excitation signal change is calculated through the adaptive signal adjustment algorithm to adjust the period and amplitude of the excitation signal; different signals including but not limited to 3211, sine signal, square wave signal, sweep frequency signal, etc. can also 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 generate a new excitation action, and then going back to step one for data collection, and then entering step two for processing and judgment until the aircraft excitation action meets the aerodynamic identification requirements, achieving the goal of adaptively matching the excitation signal with the current aircraft 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 one of the above embodiments, comprising:

[0070] A collection 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 above system can run on an integrated modular avionics core processor, which uses Freescale QorIQ T1042 as the core processing chip. The chip contains 4 e5500 cores, each core DMIPS reaches 4200; supports 32 / 64-bit mode, 4 cores share 256KB L3 cache, each core has 32KB L1 data / instruction cache, and 256KB L2 cache; supports a DDR3L / 4 memory controller; supports PCI-E 2.0, SATA 2.0, and USB 2.0 interfaces; serial ports support UART, I2C, and SPI, etc.; has multiple 5GHz frequency SerDes, which 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, which 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 above-mentioned ARINC 653Hypervisor architecture can provide the aircraft with strong computing power on the basis of low power consumption. At the same time, with the support of the ARINC 653 architecture, it can realize sensor data acquisition and control quantity output, signal filtering processing and signal closed-loop generation, flight control law and excitation signal fusion, and parameter identification algorithm running on different cores and partitions of the CPU, ensuring the independent execution of multiple tasks without mutual influence, and ensuring the smooth and correct operation of the aerodynamic parameter identification algorithm based on the closed-loop adaptive excitation signal generator.

[0077] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0078] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be 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 will not be limited to the embodiments shown herein, but rather 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; The 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 building a closed-loop adaptive excitation signal generator includes: The closed-loop adaptive excitation signal generator includes: a preprocessing module, an auxiliary analysis module, a judgment module, and an adjustment module.

3. The method for identifying aircraft aerodynamic parameters according to claim 2, characterized in that: The closed-loop adaptive excitation signal generator also includes: a signal excitation module.

4. The method for identifying aircraft aerodynamic parameters according to claim 3, characterized in that: 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; Determine, by the judgment module, whether the auxiliary analysis result can excite the short-period motion mode of the aircraft, and obtain a corresponding judgment result; The adjustment module determines whether the current excitation signal needs to be adjusted according to the judgment result.

5. The method for identifying aircraft aerodynamic parameters according to claim 4, 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 current excitation signal is processed by the signal excitation module to obtain a corresponding new excitation signal, and the new excitation signal is output to the aircraft.

6. The method for identifying aircraft aerodynamic parameters according to claim 4, 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 includes: When the auxiliary analysis result cannot excite the short-period motion mode of the aircraft, an adjustment amount of the current excitation signal is determined by an adaptive signal adjustment algorithm, 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 short-period motion mode of the aircraft; The new excitation signal is output to the aircraft.

7. The method for identifying aircraft aerodynamic parameters according to claim 6, 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 also 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.

8. The method for identifying aircraft aerodynamic parameters according to claim 6, 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 the adjustment amount of the current excitation signal by 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 the gradient descent method.

9. A system using the aircraft aerodynamic parameter identification method according to any one of claims 1 to 8, characterized in that: include: A collection module, used to collect aircraft response data; A processing module, 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; The output module is used to output the excitation signal to the aircraft.

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