A tilt-rotor aircraft radar cross section fitting method and device based on a full angle domain database

Abstract

The application discloses a tilt-rotor aircraft radar scattering cross section fitting method and equipment based on a full angle domain database, relates to the technical field of tilt-rotor aircrafts, and comprises the following steps: a full angle domain dynamic radar scattering cross section database is constructed; when the attitude of the tilt-rotor aircraft changes, the coordinates of radar observation points in an inertial coordinate system are converted to the coordinates of the radar observation points in a body coordinate system based on a conversion matrix, so that the coordinates of the radar observation points in the body coordinate system are obtained; based on the coordinates of the radar observation points in the body coordinate system, the actual incident angle of radar waves relative to the tilt-rotor aircraft under the current attitude is obtained; and based on the actual incident angle of the radar waves relative to the tilt-rotor aircraft under the current attitude and the full angle domain dynamic radar scattering cross section database, the radar scattering cross section value of the tilt-rotor aircraft under the current attitude is obtained. The application improves the efficiency and flexibility of the radar stealth performance evaluation of the tilt-rotor aircraft.

Description

Technical Field

[0001] This application relates to the field of tiltrotor aircraft technology, and in particular to a method and device for fitting the radar cross section of a tiltrotor aircraft based on a full-angle domain database. Background Technology

[0002] Tiltrotor aircraft, possessing vertical takeoff and landing, hovering, and high-speed cruise capabilities, demonstrate broad prospects for military applications, and their superior radar stealth performance has become one of their core competitive advantages. In radar stealth performance analysis, the radar cross section (RCS) is a key indicator for measuring stealth capabilities. The accurate calculation of the RCS directly affects the determination of stealth performance parameters such as the aircraft's exposure distance and probability of detection. Currently, the industry typically employs high-precision algorithms to first calculate the RCS, and then analyzes and evaluates radar stealth performance based on the obtained RCS data.

[0003] However, this analytical process has significant limitations in practical applications—changes in the flight state of tiltrotor aircraft lead to a large amount of repetitive calculations. When the aircraft's flight attitude changes, the detection angle of the radar relative to the aircraft (i.e., the incident angle of the radar wave) changes, which in turn changes the radar cross section (RCS) value of the aircraft, ultimately altering the radar stealth performance indicators. Faced with this situation, traditional analytical processes and methods require changing the parameter inputs (mainly the radar detection angle) in the high-precision method for each different flight attitude condition, recalculating the RCS under that condition, and then analyzing the radar stealth performance indicators. This results in a large number of complex and repetitive calculations. Furthermore, the high-precision RCS algorithm itself is relatively slow, ultimately leading to a significant reduction in research efficiency. At the same time, the diversity of the motion relationships between the tiltrotor aircraft's rotor, nacelle, and fuselage further multiplies the computational load of traditional analytical methods.

[0004] It is evident that traditional methods for analyzing the radar stealth performance of aircraft are inefficient and cannot meet the demands of multi-condition, rapid stealth performance analysis. Therefore, there is an urgent need for a radar cross section calculation technique that can avoid redundant calculations and adapt to complex attitude changes, in order to improve the efficiency and flexibility of radar stealth performance assessment for tiltrotor aircraft. Summary of the Invention

[0005] The purpose of this application is to provide a method and device for fitting the radar cross section of a tiltrotor aircraft based on a full-angle domain database, thereby improving the efficiency and flexibility of radar stealth performance evaluation of tiltrotor aircraft.

[0006] To achieve the above objectives, this application provides the following solution: Firstly, this application provides a method for fitting the radar cross section of a tiltrotor aircraft based on a full-angle domain database, the method comprising: Construct a full-angle dynamic radar cross section database; When the attitude of the tiltrotor aircraft changes, the coordinates of the radar observation point in the inertial coordinate system are transformed to the body coordinate system based on the transformation matrix to obtain the coordinates of the radar observation point in the body coordinate system; the transformation matrix is ​​the transformation matrix from the inertial coordinate system to the body coordinate system. Based on the coordinates of the radar observation point in the body coordinate system, the actual incident angle of the radar wave relative to the tiltrotor aircraft under the current attitude is obtained. Based on the actual incident angle of the radar wave relative to the tiltrotor aircraft in the current attitude and the full-angle dynamic radar cross section database, the radar cross section value of the tiltrotor aircraft in the current attitude is obtained.

[0007] In one embodiment, constructing a full-angle dynamic radar cross section database specifically includes: Establish a spatial reference coordinate system; the spatial reference coordinate system includes: an inertial coordinate system, a body coordinate system, and a transformation matrix for converting the inertial coordinate system to the body coordinate system; In the inertial coordinate system, radar observation points are arranged at equal intervals in the full angular domain of space. Under the condition that the body coordinate system and the inertial coordinate system coincide and the attitude angle of the tiltrotor aircraft is not considered, the static radar cross section data at each observation angle is calculated. By introducing rotor motion parameters and adding time series data to the static radar cross section data, dynamic radar cross section data under different combinations of rotor motion parameters at each observation angle are calculated, and the set of all dynamic radar cross section data is determined as a full-angle dynamic radar cross section database.

[0008] In one embodiment, establishing a spatial reference coordinate system specifically includes: Define an inertial coordinate system; where the origin of the inertial coordinate system is fixed at the center of gravity of the tiltrotor aircraft, the x-axis of the inertial coordinate system points in the direction of flight of the aircraft, the z-axis of the inertial coordinate system points in the opposite direction of gravity, the y-axis of the inertial coordinate system is determined according to the right-hand rule, and the xOy plane is parallel to the ground. Define a body coordinate system; wherein the origin of the body coordinate system is located at the center of gravity of the aircraft, the x-axis of the body coordinate system points in the direction of the nose, the z-axis of the body coordinate system is perpendicular to the x-axis and points upward, and the y-axis of the body coordinate system is determined according to the right-hand rule; Define a transformation matrix from the inertial coordinate system to the body coordinate system; wherein the transformation matrix is ​​determined by the roll angle, pitch angle and yaw angle of the tiltrotor aircraft; The inertial coordinate system, the body coordinate system, and the transformation matrix are defined as the spatial reference coordinate system.

[0009] In one embodiment, radar observation points are arranged at equal intervals across the entire spatial angular domain in the inertial coordinate system, specifically including: The pitch angle is set to a range of [-90°, 90°], and the pitch angle is discretized according to a preset first interval to obtain a set of discretized pitch angle sample values; The azimuth angle is set to a range of [0°, 360°], and the azimuth angle is discretized at a preset second interval to obtain a set of discretized azimuth angle sample values; Specifically, the pitch angle in the horizontal plane of the aircraft is 0°, the pitch angle is positive when the radar wave is incident from above, and the pitch angle is negative when the radar wave is incident from below; the azimuth angle of the nose is 0°, and the azimuth angle of the radar wave incident increases counterclockwise when viewed from above the aircraft. The observation angles of all radar observation points are determined based on the discretized set of pitch angle samples and the discretized set of azimuth angle samples.

[0010] In one embodiment, with the body coordinate system and inertial coordinate system coinciding and without considering the attitude angles of the tiltrotor aircraft, the static radar cross section data at each observation angle is calculated, specifically including: With the body coordinate system and the inertial coordinate system coinciding and without considering the attitude angle of the tiltrotor aircraft, for each set of discretized pitch angle sampling values ​​and discretized azimuth angle sampling values, a preset algorithm is used to calculate the radar cross section value at the corresponding observation angle. The radar cross section values ​​obtained from all observation angles are defined as static radar cross section data; the static radar cross section data does not contain time dimension information.

[0011] In one embodiment, the rotor motion parameters include the rotor's tilt angle, rotation angle, pitch angle, and flapping angle; By introducing rotor motion parameters and adding time series data to the static radar cross section (RCS) data, dynamic RCS data under different combinations of rotor motion parameters at each observation angle are calculated. The set of all dynamic RCS data is then defined as a full-range dynamic RCS database, specifically including: Introducing rotor motion parameters; where the rotor rotation angle is determined by the product of the rotor rotation angular velocity and time, and the rotor pitch angle and flapping angle are both functions related to the rotation angle; For each set of discretized pitch and azimuth sampling values, a time series is added to the static radar cross section data to construct dynamic radar cross section data containing the time dimension; the dynamic radar cross section data is a function related to the observation angle, time, and rotor motion parameters. Using a pre-defined numerical calculation method, dynamic radar cross section data of each observation angle at different times and under different combinations of rotor motion parameters are calculated. Dynamic radar cross section data under all observation angles, all times, and all combinations of rotor motion parameters are used to construct a full-angle dynamic radar cross section database covering the entire spatial angular domain and the rotor motion cycle.

[0012] In one embodiment, when the attitude of the tiltrotor aircraft changes, the coordinates of the radar observation point in the inertial coordinate system are transformed to the body coordinate system based on the transformation matrix to obtain the coordinates of the radar observation point in the body coordinate system. Specifically, this includes: When at least one of the roll angle, pitch angle and yaw angle of the tiltrotor aircraft changes, the spatial position of all radar observation points in the inertial coordinate system remains unchanged; Obtain the coordinates of each radar observation point in the inertial coordinate system; the coordinates of each radar observation point are determined by the observation distance and observation angle. Based on the transformation matrix, the coordinates of each radar observation point in the inertial coordinate system are transformed to the body coordinate system, thus obtaining the coordinates of each radar observation point in the body coordinate system.

[0013] In one embodiment, based on the actual incident angle of the radar wave relative to the tiltrotor aircraft at the current attitude and the full-angle dynamic radar cross section database, the radar cross section value of the tiltrotor aircraft at the current attitude is obtained, specifically including: Determine whether the actual incident angle is in the full-angle dynamic radar cross section database; If so, the radar cross section value of the tiltrotor aircraft in the current attitude is obtained by extracting the dynamic radar cross section data corresponding to the actual incident angle from the full-angle dynamic radar cross section database. If not, then the dynamic radar cross section data of multiple neighboring observation points at the actual incident angle are interpolated and fitted in the full-angle dynamic radar cross section database to obtain the radar cross section value of the tiltrotor aircraft in the current attitude.

[0014] In one embodiment, the dynamic radar cross section data of multiple neighboring observation points at the actual incident angle are interpolated and fitted in the full-angle dynamic radar cross section database to obtain the radar cross section value of the tiltrotor aircraft at the current attitude, specifically including: Based on the actual elevation angle and the actual azimuth angle, multiple neighboring observation points located near the actual elevation angle and the actual azimuth angle are determined in the full-angle dynamic radar cross section database; the multiple neighboring observation points include: two adjacent sampling points in the elevation angle direction and two adjacent sampling points in the azimuth angle direction, which together constitute four neighboring observation points surrounding the actual incident angle. Extract the dynamic radar cross section data of the four neighboring observation points at the same time from the full-angle dynamic radar cross section database; An interpolation algorithm is used to interpolate and fit the dynamic radar cross section data of the four neighboring observation points to obtain the radar cross section fitting value corresponding to the actual incident angle under the current attitude, and the radar cross section fitting value is used as the radar cross section value of the tiltrotor aircraft under the current attitude.

[0015] Secondly, this application provides a computer device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the above-described method for fitting the radar cross section of a tiltrotor aircraft based on a full-angle domain database.

[0016] According to the specific embodiments provided in this application, this application has the following technical effects: This application discloses a method and device for fitting the radar cross section (RCS) of a tiltrotor aircraft based on a full-angle domain database. By pre-constructing a full-angle domain dynamic RCS database integrating radar illumination angle, aircraft attitude parameters, and rotor dynamic parameters, the high-precision calculation task is completed in advance. In practical applications, the actual incident angle under the current attitude is first obtained through coordinate system transformation. Then, based on this angle, nearby pitch and azimuth observation points are located in the database. A mean interpolation algorithm is used to fit the RCS data of the nearby observation points, thereby quickly obtaining the RCS value under the current attitude. This fundamentally avoids the need for repeated calculations for each new attitude. The necessity of high-precision calculations: On the one hand, since the database already covers discrete observation point data in the full-angle domain and multiple states, the RCS under any attitude can be obtained in real time through low-computation interpolation, which greatly improves the efficiency of multi-condition analysis; on the other hand, the multi-dimensional parameter coverage of the database ensures that the changes in the aircraft's attitude and the dynamic adjustment of the rotor can be accurately mapped to the changes in RCS, which enhances the adaptability and realism of the method. While ensuring the fitting accuracy, it liberates the stealth performance evaluation from lengthy repetitive calculations, significantly shortens the design iteration cycle, and provides efficient and reliable technical support for the stealth optimization and multi-scenario verification of tiltrotor aircraft. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic flowchart of a method for fitting the radar cross section of a tiltrotor aircraft based on a full-angle domain database, provided in an embodiment of this application; Figure 2 A schematic diagram comparing the fitting results and numerical calculation results for a roll angle of 5.2° provided in an embodiment of this application; Figure 3 A schematic diagram comparing the fitting results and numerical calculation results for a roll angle of 8.9° provided in an embodiment of this application; Figure 4 This is a schematic diagram of the structure of a computer device provided in an embodiment of this application. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0020] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] In one exemplary embodiment, such as Figure 1 As shown, a method for fitting the radar cross section of a tiltrotor aircraft based on a full-angle domain database is provided. This method is executed by a computer device, specifically by a terminal or server alone, or by both a terminal and a server. In this embodiment, the method is described using a server as an example, and includes the following steps: Step S1: Construct a full-angle dynamic radar cross section database.

[0022] As an optional implementation method, step S1 specifically includes: Step S11: Establish a spatial reference coordinate system; the spatial reference coordinate system includes: an inertial coordinate system, a body coordinate system, and a transformation matrix for converting the inertial coordinate system to the body coordinate system.

[0023] As an optional implementation, step S11 specifically includes: Step S111: Define an inertial coordinate system; wherein, the origin of the inertial coordinate system is fixed at the center of gravity of the tiltrotor aircraft, the x-axis of the inertial coordinate system points in the direction of flight of the aircraft, the z-axis of the inertial coordinate system points in the opposite direction of gravity, the y-axis of the inertial coordinate system is determined according to the right-hand rule, and the xOy plane is parallel to the ground.

[0024] Step S112, define the body coordinate system; wherein, the origin of the body coordinate system is located at the center of gravity of the aircraft (moving and rotating together with the movement of the tiltrotor aircraft), the x-axis of the body coordinate system points in the direction of the nose, the z-axis of the body coordinate system is perpendicular to the x-axis and upwards, and the y-axis of the body coordinate system is determined according to the right-hand rule.

[0025] Step S113: Define the transformation matrix from the inertial coordinate system to the body coordinate system; wherein the transformation matrix is ​​determined by the roll angle, pitch angle and yaw angle of the tiltrotor aircraft.

[0026] Step S114: Determine the inertial coordinate system, the body coordinate system, and the transformation matrix as the spatial reference coordinate system.

[0027] In addition, prior to step S11, the following multi-dimensional influencing factors are set in the dynamic RCS database of the tiltrotor aircraft across the entire angular domain: radar illumination angle, i.e., the pitch angle of the incident radar wave. and azimuth The attitude parameters of a tiltrotor aircraft, namely the roll angle of the airframe. Pitch angle and yaw angle Rotor motion parameters, namely the rotor blade rotation angle. ( The rotor's angular velocity, For time, , (1 / 3 of the rotor's rotation cycle), rotor tilt angle Variable pitch angle and waving corner Among them, the pitch angle and the swing angle are related to time, and are This function enables the one-time pre-calculation and centralized storage of core RCS data.

[0028] Specifically, the full-angle dynamic RCS database is built on a coordinate system. First, the two coordinate systems mentioned above are defined. Then, the transformation matrix is ​​calculated. Among them, the roll angle of the tiltrotor aircraft... Pitch angle and yaw angle The transformation matrix from the inertial coordinate system to the body coordinate system. for: (1) Step S12: In the inertial coordinate system, radar observation points are arranged at equal intervals in the full angular domain of space. Under the condition that the body coordinate system and the inertial coordinate system coincide and the attitude angle of the tiltrotor aircraft is not considered, the static radar cross section data at each observation angle is calculated.

[0029] As an optional implementation, in step S12, radar observation points are arranged at equal intervals across the entire spatial angular domain in the inertial coordinate system, specifically including: Step S1211: Set the pitch angle range to [-90°, 90°], and discretize the pitch angle according to a preset first interval to obtain a set of discretized pitch angle sample values.

[0030] Step S1212: Set the azimuth angle range to [0°, 360°], and discretize the azimuth angle at a preset second interval to obtain a set of discretized azimuth angle sample values. Specifically, the elevation angle within the horizontal plane of the aircraft is 0°; the elevation angle is positive when the radar wave is incident from above and negative when the radar wave is incident from below. The nose-pointing azimuth angle is 0°; when viewed from above the aircraft, the radar wave incident azimuth angle increases counterclockwise.

[0031] Step S1213: Based on the discretized set of sampled elevation angles and the discretized set of sampled azimuth angles, determine the observation angles of all radar observation points.

[0032] As an optional implementation, in step S12, with the body coordinate system and inertial coordinate system coinciding and without considering the attitude angle of the tiltrotor aircraft, the static radar cross section data at each observation angle is calculated, specifically including: Step S1221: With the body coordinate system and the inertial coordinate system coinciding and without considering the attitude angle of the tiltrotor aircraft, for each set of discretized pitch angle sampling values ​​and discretized azimuth angle sampling values, a preset algorithm is used to calculate the radar cross section value at the corresponding observation angle.

[0033] Step S1222: The calculated radar cross section values ​​at all observation angles are determined as static radar cross section data; the static radar cross section data does not contain time dimension information.

[0034] Specifically, first, the body coordinate system is aligned with the inertial coordinate system. The roll, pitch, and yaw angles of the tiltrotor aircraft are disregarded. At this point, observation radars are deployed across the entire spatial angular domain, including the elevation angle range. ,interval azimuth range ,interval Pitch angle within the horizontal plane of the aircraft The elevation angle of radar waves incident from above is positive, and the elevation angle of radar waves incident from below is negative; the azimuth angle of the aircraft's nose. Radar wave incident azimuth angle viewed from above the aircraft Arranged counterclockwise. Write the RCS for each observation angle as follows: ,Right now For static radar cross section data (excluding) ).

[0035] Step S13: Introduce rotor motion parameters and add time series to the static radar cross section data to calculate dynamic radar cross section data for each observation angle under different combinations of rotor motion parameters. Then, determine the set of all dynamic radar cross section data as the full-angle dynamic radar cross section database.

[0036] As an optional implementation, the rotor motion parameters include the rotor's tilt angle, rotation angle, pitch angle, and flapping angle. Step S13 specifically includes: Step S131, introduce rotor motion parameters; wherein, the rotor rotation angle is determined by the product of the rotor rotation angular velocity and time, and the rotor pitch angle and flapping angle are both functions related to the rotation angle.

[0037] Step S132: For each set of discretized pitch angle sampling values ​​and azimuth angle sampling values, a time series is added to the static radar cross section data to construct dynamic radar cross section data containing the time dimension; the dynamic radar cross section data is a function related to the observation angle, time, and rotor motion parameters.

[0038] Step S133: Using a preset numerical calculation method, calculate the dynamic radar cross section data of each observation angle at different times and under different combinations of rotor motion parameters.

[0039] Step S134: Construct a full-angle dynamic radar cross section database covering the entire spatial angular domain and the rotor motion cycle using dynamic radar cross section data under all observation angles, all times, and all combinations of rotor motion parameters.

[0040] Specifically, the tilt angle, rotation angle, pitch angle, and flapping angle of the rotor are introduced, and the obtained static radar cross-section data are analyzed. Add a time series data point and convert it into a dynamic RCS dataset on the time axis: (2) in, n The number of discrete points (representing the discretization of continuous time).

[0041] Therefore, the dynamic RCS data set of the full-angle domain is: (3) Among them, the dynamic RCS data set of the full-angle domain in the above formula It can be calculated directly using high-precision numerical methods.

[0042] Step S2: When the attitude of the tiltrotor aircraft changes, the coordinates of the radar observation point in the inertial coordinate system are transformed to the body coordinate system based on the transformation matrix to obtain the coordinates of the radar observation point in the body coordinate system; the transformation matrix is ​​the transformation matrix from the inertial coordinate system to the body coordinate system.

[0043] As an optional implementation method, step S2 specifically includes: Step S21: When at least one of the roll angle, pitch angle and yaw angle of the tiltrotor aircraft changes, the spatial position of all radar observation points in the inertial coordinate system remains unchanged.

[0044] Step S22: Obtain the coordinates of each radar observation point in the inertial coordinate system; the coordinates of each radar observation point are determined by the observation distance and the observation angle. The observation distance satisfies the far-field condition, and the observation angle is determined by the discretized pitch angle sampled values ​​and the discretized azimuth angle sampled values.

[0045] Step S23: Based on the transformation matrix, transform the coordinates of each radar observation point in the inertial coordinate system to the body coordinate system to obtain the coordinates of each radar observation point in the body coordinate system.

[0046] Specifically, the effects of airframe roll angle, pitch angle, and yaw angle are introduced into the obtained dynamic RCS data set across the entire angular domain. Based on this, RCS data (i.e., full-angle RCS database) under any attitude angle can be obtained through interpolation methods.

[0047] In the inertial coordinate system, the coordinates of radar observation points evenly distributed spherically across the entire angular domain can be expressed as follows: express, Representing an infinitely large distance, this represents the distance from the detection radar to the aircraft (an infinitely large distance is used to satisfy the far-field assumption in the RCS calculation method). For ease of processing, the distance coordinates are normalized, and the radar observation point coordinates become... .

[0048] Keeping the radar observation point's coordinates in space (inertial coordinate system) constant, the relative incident angle of the radar wave will change due to the aircraft's attitude angle. In the body coordinate system, the coordinates of the radar observation point become: (4) in, These represent the x, y, and z axis values ​​of the radar observation point location in the aircraft coordinate system.

[0049] Step S3: Based on the coordinates of the radar observation point in the body coordinate system, obtain the actual incident angle of the radar wave relative to the tiltrotor aircraft in the current attitude.

[0050] Specifically, the actual incident angle of the radar wave relative to the tiltrotor aircraft for: (5) The actual angle of incidence obtained Subsequently, dynamic RCS dataset Represented as: (6) Step S4: Based on the actual incident angle of the radar wave relative to the tiltrotor aircraft in the current attitude and the full-angle dynamic radar cross section database, obtain the radar cross section value of the tiltrotor aircraft in the current attitude.

[0051] As an optional implementation, step S4 specifically includes: Step S41: Determine whether the actual incident angle is in the full-angle dynamic radar cross section database.

[0052] Step S42, if yes, then based on extracting the dynamic radar cross section data corresponding to the actual incident angle from the full-angle dynamic radar cross section database, the radar cross section value of the tiltrotor aircraft in the current attitude is obtained.

[0053] Step S43: If not, interpolate and fit the dynamic radar cross section data of multiple neighboring observation points at the actual incident angle in the full-angle dynamic radar cross section database to obtain the radar cross section value of the tiltrotor aircraft in the current attitude.

[0054] As an optional implementation, in step S43, the dynamic radar cross section data of multiple neighboring observation points at the actual incident angle are interpolated and fitted in the full-angle dynamic radar cross section database to obtain the radar cross section value of the tiltrotor aircraft in the current attitude, specifically including: Step S431: Based on the actual elevation angle and the actual azimuth angle, determine multiple neighboring observation points located near the actual elevation angle and the actual azimuth angle in the full-angle dynamic radar cross section database; the multiple neighboring observation points include: two adjacent sampling points in the elevation angle direction and two adjacent sampling points in the azimuth angle direction, which together constitute four neighboring observation points surrounding the actual incident angle.

[0055] Step S432: Extract the dynamic radar cross section data of the four neighboring observation points at the time corresponding to the current time from the full-angle dynamic radar cross section database.

[0056] Step S433: Using an interpolation algorithm, the dynamic radar cross section data of the four neighboring observation points are interpolated and fitted to obtain the radar cross section fitting value corresponding to the actual incident angle under the current attitude, and the radar cross section fitting value is used as the radar cross section value of the tiltrotor aircraft under the current attitude.

[0057] Specifically, interpolation methods are used for... The fitting process is performed as follows: (7) Where i represents the pitch direction index, used to distinguish between two adjacent pitch angle observations; j represents the azimuth direction index, used to distinguish between two adjacent azimuth observations.

[0058] The above formula means: the elevation angle and azimuth angle of the observation point are... and Within range Find the mean, as The value of satisfies the following assignment conditions: (8) In order to handle boundary points, the elevation angle is defined from -90 to 90° and the azimuth angle is defined from 0° to 360°. During the aforementioned coordinate system transformation, there may be cases where the radar incident elevation angle is less than -90° or greater than 90°, and the azimuth angle is less than 0° or greater than 360°. In this case, correction is required, that is, the points less than -90° are assigned the values ​​of the -90° points, and then the corresponding values ​​are assigned using equation (8).

[0059] Therefore, at the incident elevation angle is azimuth angle is Under radar illumination, the radar cross section (RCS) of a tiltrotor aircraft flying in any attitude can be directly extracted by fitting the established full-range dynamic radar cross section database. When the aircraft flies in any attitude, the incident angle of the radar wave is also arbitrary, but it is always surrounded by four neighboring observation points whose RCS has been pre-calculated. Therefore, the RCS of the aircraft after attitude changes can be interpolated and fitted using the RCS values ​​of these four neighboring observation points. The fitting accuracy is related to the distribution density of the database observation points; the higher the distribution density, the higher the fitting accuracy.

[0060] It is important to note that the full-angle dynamic radar cross section (RCS) database in this application is constructed for a specific type of tiltrotor aircraft, reflecting the inherent electromagnetic scattering characteristics of that type of aircraft. This means that a corresponding full-angle dynamic RCS database needs to be established for each type of tiltrotor aircraft. When the aircraft model or configuration changes, the corresponding database needs to be reconstructed. For the same type of aircraft, once the database is constructed, it can be used throughout its entire lifecycle to quickly fit the RCS value under any operating condition by acquiring real-time attitude and rotor motion parameters.

[0061] Based on the radar cross section fitting method for tiltrotor aircraft using a full-range database proposed in this application, this paper focuses on a specific type of tiltrotor aircraft. Roll angles of 5.2° and 8.9° are selected. A full-range dynamic RCS database is used to interpolate and fit the dynamic RCS of the entire aircraft in the horizontal plane. The radar operates at a frequency of 3 GHz with horizontal polarization, resulting in the following: Figures 2-3 The diagram shows a comparison between the fitting results (the method of this application) and the results calculated by the numerical method.

[0062] from Figures 2-3 As can be seen, under two different roll angle attitudes, the numerical calculation results and the interpolation fitting results are in high agreement, with average errors of only 0.03dB and 0.06dB, respectively. This demonstrates that the full-angle dynamic RCS database for tiltrotor aircraft established by the method in this application can directly interpolate and fit other states based on dynamic RCS data at existing observation points, with high accuracy and significantly improved computational efficiency.

[0063] Beneficial effects: This application discloses a tiltrotor aircraft RCS fitting method based on a full-angle domain database, aiming to solve the problems of redundant calculations and low efficiency caused by changes in aircraft attitude and adjustments in radar detection angles in traditional RCS calculations. Specifically: 1) Significantly improves computational efficiency and avoids redundant calculations. By pre-constructing a full-range dynamic RCS database covering radar illumination angle, aircraft attitude parameters, and rotor dynamic parameters, rapid acquisition of RCS data for tiltrotor aircraft under arbitrary attitudes and detection angles is achieved. This method eliminates the need for repetitive high-precision numerical calculations for different flight states, significantly reducing the computational overhead of multi-condition analysis.

[0064] 2) High fitting accuracy and strong reliability By employing the mean interpolation method of nearby observation points, the RCS value of the target working condition can be efficiently fitted based on preset observation points in the database. The fitting accuracy is positively correlated with the density of observation points in the database. Verification through examples shows that the average error is only 0.03dB to 0.06dB, meeting the accuracy requirements of engineering applications.

[0065] 3) Simplify the stealth performance evaluation process By relying on the database to extract and fit RCS data, the process of evaluating the stealth performance of tiltrotor aircraft in multiple scenarios and attitudes is effectively simplified, providing efficient technical support for the optimization of aircraft stealth design.

[0066] 4) Supports dynamic response of multi-dimensional parameters The database integrates multiple influencing factors such as attitude parameters and rotor dynamic parameters, which can accurately reflect the changes in electromagnetic scattering characteristics of the aircraft during actual flight, thus improving the authenticity and adaptability of the RCS fitting results.

[0067] 5) Provide a universal platform for stealth design and verification This method is not only applicable to the rapid RCS assessment of the current model, but can also be extended to the stealth design and performance verification of other tiltrotor aircraft, demonstrating strong versatility and scalability.

[0068] In one exemplary embodiment, a computer device is provided, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement a method for fitting the radar cross section of a tiltrotor aircraft based on a full-angle domain database.

[0069] In one exemplary embodiment, a computer-readable storage medium is provided having a computer program stored thereon that, when executed by a processor, implements a method for fitting the radar cross section of a tiltrotor aircraft based on a full-angle domain database.

[0070] In one exemplary embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements a method for fitting the radar cross section of a tiltrotor aircraft based on a full-angle domain database.

[0071] In one exemplary embodiment, a computer device is provided, which may be a server or a terminal, and its internal structure diagram may be as follows. Figure 4As shown, this computer device includes a processor, memory, input / output (I / O) interfaces, and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is also connected to the system bus via the I / O interfaces. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and a database. The internal memory provides the environment for the operating system and computer programs stored in the non-volatile storage media to run. The I / O interfaces are used for exchanging information between the processor and external devices. The communication interface is used for communicating with external terminals via a network connection. When the computer program is executed by the processor, it implements a method for fitting the radar cross section of a tiltrotor aircraft based on a full-angle domain database.

[0072] Those skilled in the art will understand that Figure 4 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0073] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0074] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM).

[0075] The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based tiltrotor aircraft logic devices, etc., and are not limited to these.

[0076] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0077] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for fitting the radar cross section of a tiltrotor aircraft based on a full-angle domain database, characterized in that, The method for fitting the radar cross section of a tiltrotor aircraft based on a full-angle domain database includes: Construct a full-angle dynamic radar cross section database; When the attitude of the tiltrotor aircraft changes, the coordinates of the radar observation point in the inertial coordinate system are transformed to the body coordinate system based on the transformation matrix to obtain the coordinates of the radar observation point in the body coordinate system; the transformation matrix is ​​the transformation matrix from the inertial coordinate system to the body coordinate system. Based on the coordinates of the radar observation point in the body coordinate system, the actual incident angle of the radar wave relative to the tiltrotor aircraft under the current attitude is obtained. Based on the actual incident angle of the radar wave relative to the tiltrotor aircraft in the current attitude and the full-angle dynamic radar cross section database, the radar cross section value of the tiltrotor aircraft in the current attitude is obtained.

2. The method for fitting the radar cross section of a tiltrotor aircraft based on a full-angle domain database according to claim 1, characterized in that, Constructing a full-angle dynamic radar cross section database, specifically including: Establish a spatial reference coordinate system; the spatial reference coordinate system includes: an inertial coordinate system, a body coordinate system, and a transformation matrix for converting the inertial coordinate system to the body coordinate system; In the inertial coordinate system, radar observation points are arranged at equal intervals in the full angular domain of space. Under the condition that the body coordinate system and the inertial coordinate system coincide and the attitude angle of the tiltrotor aircraft is not considered, the static radar cross section data at each observation angle is calculated. By introducing rotor motion parameters and adding time series data to the static radar cross section data, dynamic radar cross section data under different combinations of rotor motion parameters at each observation angle are calculated, and the set of all dynamic radar cross section data is determined as a full-angle dynamic radar cross section database.

3. The method for fitting the radar cross section of a tiltrotor aircraft based on a full-angle domain database according to claim 2, characterized in that, Establishing a spatial reference coordinate system specifically includes: Define an inertial coordinate system; where the origin of the inertial coordinate system is fixed at the center of gravity of the tiltrotor aircraft, the x-axis of the inertial coordinate system points in the direction of flight of the aircraft, the z-axis of the inertial coordinate system points in the opposite direction of gravity, the y-axis of the inertial coordinate system is determined according to the right-hand rule, and the xOy plane is parallel to the ground. Define a body coordinate system; wherein the origin of the body coordinate system is located at the center of gravity of the aircraft, the x-axis of the body coordinate system points in the direction of the nose, the z-axis of the body coordinate system is perpendicular to the x-axis and points upward, and the y-axis of the body coordinate system is determined according to the right-hand rule; Define a transformation matrix from the inertial coordinate system to the body coordinate system; wherein the transformation matrix is ​​determined by the roll angle, pitch angle and yaw angle of the tiltrotor aircraft; The inertial coordinate system, the body coordinate system, and the transformation matrix are defined as the spatial reference coordinate system.

4. The method for fitting the radar cross section of a tiltrotor aircraft based on a full-angle domain database according to claim 3, characterized in that, In the inertial coordinate system, radar observation points are arranged at equal intervals across the entire spatial angular domain, specifically including: The pitch angle is set to a range of [-90°, 90°], and the pitch angle is discretized according to a preset first interval to obtain a set of discretized pitch angle sample values; The azimuth angle is set to a range of [0°, 360°], and the azimuth angle is discretized at a preset second interval to obtain a set of discretized azimuth angle sample values; Specifically, the pitch angle in the horizontal plane of the aircraft is 0°, the pitch angle is positive when the radar wave is incident from above, and the pitch angle is negative when the radar wave is incident from below; the azimuth angle of the nose is 0°, and the azimuth angle of the radar wave incident increases counterclockwise when viewed from above the aircraft. The observation angles of all radar observation points are determined based on the discretized set of pitch angle samples and the discretized set of azimuth angle samples.

5. The method for fitting the radar cross section of a tiltrotor aircraft based on a full-angle domain database according to claim 4, characterized in that, Under the condition that the body coordinate system and the inertial coordinate system coincide and the attitude angle of the tiltrotor aircraft is not considered, the static radar cross section data at each observation angle is calculated, specifically including: With the body coordinate system and the inertial coordinate system coinciding and without considering the attitude angle of the tiltrotor aircraft, for each set of discretized pitch angle sampling values ​​and discretized azimuth angle sampling values, a preset algorithm is used to calculate the radar cross section value at the corresponding observation angle. The radar cross section values ​​obtained from all observation angles are defined as static radar cross section data; the static radar cross section data does not contain time dimension information.

6. The method for fitting the radar cross section of a tiltrotor aircraft based on a full-angle domain database according to claim 5, characterized in that, The rotor motion parameters include the rotor's tilt angle, rotation angle, pitch angle, and flapping angle; By introducing rotor motion parameters and adding time series data to the static radar cross section (RCS) data, dynamic RCS data under different combinations of rotor motion parameters at each observation angle are calculated. The set of all dynamic RCS data is then defined as a full-range dynamic RCS database, specifically including: Introducing rotor motion parameters; where the rotor rotation angle is determined by the product of the rotor rotation angular velocity and time, and the rotor pitch angle and flapping angle are both functions related to the rotation angle; For each set of discretized pitch and azimuth sampling values, a time series is added to the static radar cross section data to construct dynamic radar cross section data containing the time dimension; the dynamic radar cross section data is a function related to the observation angle, time, and rotor motion parameters. Using a pre-defined numerical calculation method, dynamic radar cross section data of each observation angle at different times and under different combinations of rotor motion parameters are calculated. Dynamic radar cross section data under all observation angles, all times, and all combinations of rotor motion parameters are used to construct a full-angle dynamic radar cross section database covering the entire spatial angular domain and the rotor motion cycle.

7. The method for fitting the radar cross section of a tiltrotor aircraft based on a full-angle domain database according to claim 6, characterized in that, When the attitude of the tiltrotor aircraft changes, the coordinates of the radar observation point in the inertial coordinate system are transformed to the body coordinate system based on the transformation matrix, resulting in the coordinates of the radar observation point in the body coordinate system. Specifically, this includes: When at least one of the roll angle, pitch angle and yaw angle of the tiltrotor aircraft changes, the spatial position of all radar observation points in the inertial coordinate system remains unchanged; Obtain the coordinates of each radar observation point in the inertial coordinate system; the coordinates of each radar observation point are determined by the observation distance and observation angle. Based on the transformation matrix, the coordinates of each radar observation point in the inertial coordinate system are transformed to the body coordinate system, thus obtaining the coordinates of each radar observation point in the body coordinate system.

8. The method for fitting the radar cross section of a tiltrotor aircraft based on a full-angle domain database according to claim 7, characterized in that, Based on the actual incident angle of the radar wave relative to the tiltrotor aircraft at the current attitude and the full-angle dynamic radar cross section database, the radar cross section value of the tiltrotor aircraft at the current attitude is obtained, specifically including: Determine whether the actual incident angle is in the full-angle dynamic radar cross section database; If so, the radar cross section value of the tiltrotor aircraft in the current attitude is obtained by extracting the dynamic radar cross section data corresponding to the actual incident angle from the full-angle dynamic radar cross section database. If not, then the dynamic radar cross section data of multiple neighboring observation points at the actual incident angle are interpolated and fitted in the full-angle dynamic radar cross section database to obtain the radar cross section value of the tiltrotor aircraft in the current attitude.

9. The method for fitting the radar cross section of a tiltrotor aircraft based on a full-angle domain database according to claim 8, characterized in that, Interpolation fitting is performed on the dynamic radar cross section data of multiple neighboring observation points at the actual incident angle in the full-angle dynamic radar cross section database to obtain the radar cross section value of the tiltrotor aircraft in the current attitude, specifically including: Based on the actual elevation angle and the actual azimuth angle, multiple neighboring observation points located near the actual elevation angle and the actual azimuth angle are determined in the full-angle dynamic radar cross section database; the multiple neighboring observation points include: two adjacent sampling points in the elevation angle direction and two adjacent sampling points in the azimuth angle direction, which together constitute four neighboring observation points surrounding the actual incident angle. From the full-angle dynamic radar cross section database, extract the dynamic radar cross section data of the four neighboring observation points at the time corresponding to the current time; An interpolation algorithm is used to interpolate and fit the dynamic radar cross section data of the four neighboring observation points to obtain the radar cross section fitting value corresponding to the actual incident angle under the current attitude, and the radar cross section fitting value is used as the radar cross section value of the tiltrotor aircraft under the current attitude.

10. A computer device, comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the computer program to implement the tiltrotor aircraft radar cross section fitting method based on a full-angle domain database as described in any one of claims 1-9.

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