Three-dimensional stress feature extraction method based on track coordinate system transformation

Abstract

The invention provides a three-dimensional stress feature extraction method based on track coordinate system transformation. The method comprises the steps that a track coordinate system changing along with time is established; performing center smoothing by using a second-order 21-point least square method, and extracting the speed from the motion trail data; performing center smoothing by using a second-order 21-point least square method, and extracting acceleration from the extracted speed data; and calculating a three-dimensional acceleration vector of the target under the established track coordinate system by using coordinate transformation according to the extracted acceleration, and taking the three-dimensional acceleration vector as a three-dimensional stress feature of the target. Forward, lateral and longitudinal acceleration values of the target at each moment in the flight process are obtained through track coordinate system transformation, the values can serve as time-varying three-dimensional stress characteristics of the target, and the three-dimensional stress characteristics represent the maneuverability of the high-speed flight target in the atmosphere in all directions.

Description

Technical Field

[0001] The present invention belongs to the technical field of data processing of high-speed flying targets in the atmosphere, and specifically relates to a method for extracting three-dimensional force characteristics based on track coordinate system transformation, and more specifically relates to a method for extracting three-dimensional force characteristics during target atmospheric flight through track coordinate system transformation. Background Art

[0002] Compared with traditional exoatmospheric targets, high-speed flying targets in the atmosphere have advantages such as low flight altitude and strong maneuverability. Unlike traditional exoatmospheric targets, high-speed flying targets in the atmosphere pay more attention to their maneuverability characteristics, such as: the forward thrust capability of their carrier to the target during the active phase of flight; and the lateral maneuverability and longitudinal lifting capability that their unique structure can withstand during the gliding phase of flight. These capabilities determine the flight trajectory of the target and the possibility of being intercepted during flight, and are important characteristic parameters of the target. Whether in the field test mission of high-speed flying targets in the atmosphere or in actual combat mode, it is of great significance to extract the forward, lateral, and longitudinal three-dimensional force characteristics of the target through motion trajectory data and estimate its maneuverability in all directions.

[0003] At present, the research focuses on the track estimation, prediction, and interception of high-speed flying targets in the atmosphere. In track estimation, the geocentric system is often used as the reference coordinate, and the estimated three-dimensional acceleration is mainly used for track prediction. Since the direction of the three-dimensional acceleration in the geocentric system is inconsistent with the target's flight direction, the existing methods are difficult to use to evaluate the target's maneuverability. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that the existing technology cannot evaluate the maneuverability of high-speed flying targets in the atmosphere, and to provide a three-dimensional force feature extraction method based on track coordinate system transformation. The method can obtain the forward, lateral, and longitudinal acceleration values ​​on the target flight track. These values ​​represent the three-dimensional maneuverability of the target and can be used as maneuverability characteristic evaluation parameters.

[0005] To achieve the above purpose, the technical solution provided by the present invention is:

[0006] A three-dimensional force feature extraction method based on track coordinate system transformation includes the following steps:

[0007] Step 1: Establish a track coordinate system that changes over time:

[0008]

[0009]

[0010]

[0011] In the formula, and are the three-dimensional position vectors of the high-speed flying target in the atmosphere at three consecutive and equally spaced moments i, j, and k in the launch coordinate system, the station coordinate system, or the geocentric coordinate system, respectively. and are the unit vectors of the X-axis, Y-axis and Z-axis of the track coordinate system respectively;

[0012] Step 2: Use the second-order 21-point least squares method to perform center smoothing and extract the velocity from the motion estimation data:

[0013]

[0014] In the formula, is the velocity in any dimension at the middle moment j of 21 o'clock, h is the sampling interval of position data, w i is the speed coefficient, w i =(n-11) / 770, n=1,2,…,21,p i is any dimensional position;

[0015] Step 3, use the second-order 21-point least squares method to perform center smoothing and extract the acceleration from the extracted velocity data:

[0016]

[0017] In the formula, is the acceleration in any dimension at the middle moment j of 21 o'clock, m is the time interval of velocity data, q i is the acceleration coefficient, q i =(n-11) / 770,n=1,2,…,21,v i is the velocity in any dimension;

[0018] Step 4: Based on the extracted acceleration, use coordinate transformation to calculate the target three-dimensional acceleration vector in the established track coordinate system. Three-dimensional force characteristics with three-dimensional acceleration vector as the target:

[0019]

[0020] Furthermore, the forward acceleration represents the thrust or drag characteristics of the target, the lateral acceleration represents the lateral maneuvering force characteristics of the target, and the longitudinal acceleration represents the lift or lowering force characteristics of the target.

[0021] Furthermore, when the forward acceleration is a positive value, it indicates the thrust characteristics of the target, and when the forward acceleration is a negative value, it indicates the resistance characteristics of the target; when the lateral acceleration is a positive value, it indicates the leftward maneuvering force characteristics of the target, and when the lateral acceleration is a negative value, it indicates the rightward maneuvering force characteristics of the target; when the longitudinal acceleration is a positive value, it indicates the lift characteristics of the target, and when the lateral acceleration is a negative value, it indicates the downforce characteristics of the target.

[0022] The advantages of the present invention are:

[0023] 1. The three-dimensional force feature extraction method based on track coordinate system transformation of the present invention first constructs a track coordinate system that changes with time through the common rectangular coordinate system position data, then calculates the acceleration using the common rectangular coordinate system position data, and finally converts the acceleration at each moment in the common rectangular coordinate system to the track coordinate system at the corresponding moment, thereby obtaining the forward, lateral, and longitudinal acceleration values ​​at each moment in the target's flight process. These values ​​can be used as the three-dimensional force characteristics of the target that change with time. These force characteristic values ​​in three dimensions represent the various directional maneuverability of high-speed flying targets in the atmosphere.

[0024] 2. The present invention can be used to extract the force characteristics of any aerospace flight target in the forward, lateral and longitudinal directions, and can evaluate its flight status, maneuverability and other performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and / or other features and advantages of the present invention will become more easily understood through the following description with reference to the accompanying drawings, which are not drawn to scale and some features are exaggerated or reduced to show details of specific components. In the accompanying drawings:

[0026] Figure 1 It is a flow chart of the three-dimensional force feature extraction method based on track coordinate system transformation of the present invention;

[0027] Figure 2 It is the initial moment track coordinate system constructed by simulating the motion trajectory in the example of the present invention;

[0028] Figure 3 The acceleration curve of the simulated motion trajectory target in the geocentric coordinate system obtained in the example of the present invention;

[0029] Figure 4 The present invention obtains a three-dimensional force characteristic curve of a simulated motion trajectory target in an example. DETAILED DESCRIPTION

[0030] The present invention will be described in detail below with reference to the accompanying drawings by means of exemplary embodiments of the present invention. It should be noted that the following detailed description of the present invention is only for the purpose of illustration, and is not intended to limit the present invention.

[0031] The present invention provides a three-dimensional force feature extraction method based on track coordinate system transformation, which is used to obtain the forward, lateral and longitudinal acceleration values ​​of a high-speed flying target in the atmosphere at each moment during the flight process as the three-dimensional force characteristics of the target changing with time. These values ​​characterize the various directional maneuverability of the high-speed flying target in the atmosphere, and can solve the problem that the existing technology cannot evaluate the maneuverability of the high-speed flying target in the atmosphere.

[0032] Reference Figure 1 As an exemplary embodiment of the present invention, a three-dimensional force feature extraction method based on track coordinate system transformation includes the following steps:

[0033] Step S1, establishing a track coordinate system that changes with time;

[0034] Step S2, using the second-order 21-point least squares method to perform center smoothing and extract the speed from the motion trajectory data;

[0035] Step S3, using a second-order 21-point least squares method to perform center smoothing and extract acceleration from the extracted velocity data;

[0036] Step S4, based on the extracted acceleration, a three-dimensional acceleration vector of the target in the established track coordinate system is calculated by using coordinate transformation, and the three-dimensional acceleration vector is used as the three-dimensional force characteristic of the target.

[0037] In step S1, the trajectory coordinate system takes the reference target mass center as the origin, the target flight direction as the X-axis, the vertical target motion trajectory plane and the direction to the left as the Y-axis, and the Z-axis, X-axis, and Y-axis form a right-handed rectangular coordinate system.

[0038] Suppose the position coordinates of the high-speed flying target in the atmosphere at three consecutive and equally spaced moments i, j, k in any rectangular coordinate system such as the launch coordinate system, the station coordinate system or the geocentric coordinate system are [x i ,y i ,z i ]、[x j ,y j ,z j ]、[x k ,y k ,z k ], and record each position coordinate as a three-dimensional position vector Then the track coordinate system of the target at the middle time j can be defined as follows:

[0039]

[0040]

[0041] Where × is the cross product in the vector operator. Formula (1) is the unit vector of the X-axis of the defined track coordinate system, which represents the forward direction of the target, and the positive direction is the forward direction; Formula (2) is the unit vector of the Y-axis of the defined track coordinate system, which represents the lateral direction of the target, and the positive direction is the left direction; Formula (3) is the unit vector of the Z-axis of the defined track coordinate system, which represents the longitudinal direction of the target, and the positive direction is the ascending direction.

[0042] In steps S2 and S3, the second-order 21-point least squares method refers to a second-order least squares method that uses 21 data points for calculation.

[0043] The formula for extracting speed from motion trajectory data using the second-order 21-point least squares method is as follows:

[0044]

[0045] In the formula, is the speed in any dimension at the middle moment j of 21 o'clock, which can be specifically or h is the position data sampling interval; w i =(n-11) / 770(n=1,2,…,21), is the speed coefficient; p i is any dimensional position, specifically x i ,y i or i .

[0046] The acceleration can be extracted from the velocity data by using the second-order 21-point least squares method for center smoothing:

[0047]

[0048] In the formula, is the acceleration in any dimension at the middle moment j of 21 o'clock, which can be specifically or m is the time interval of speed data; q i =(n-11) / 770(n=1,2,…,21), is the acceleration coefficient, m and q i The specific values ​​of are the same as h and w in expression (4) i Same; v i is the velocity in any dimension, the same as in expression (4) Specifically, it can be or

[0049] For step S4, assume that the acceleration of the target at time j in the corresponding rectangular coordinate system mentioned above is Denoted as the three-dimensional acceleration vector Using the track coordinate system defined by expressions (1), (2), and (3), the acceleration vector of the target in the track coordinate system at time j can be expressed as:

[0050]

[0051] In the formula, · is the dot product in the vector operator. This expression is the acceleration coordinate transformation. Through this coordinate transformation, the forward, lateral, and longitudinal acceleration values ​​of the target at each moment during flight can be obtained. These values ​​can characterize the three-dimensional force characteristics of the target that change over time.

[0052] Therefore, as described above, the present invention first constructs a track coordinate system that changes with time through the common rectangular coordinate system position data, then uses the common rectangular coordinate system position data to calculate the acceleration, and finally converts the acceleration at each moment in the common rectangular coordinate system to the track coordinate system at the corresponding moment, thereby obtaining the forward, lateral, and longitudinal acceleration values ​​at each moment in the target flight process. These values ​​can be used as the three-dimensional force characteristics of the target that change with time. These force characteristic values ​​in three dimensions represent the maneuverability of the high-speed flying target in the atmosphere in all directions. The results obtained by the present invention have clear physical meanings and can be used to extract the force characteristics of any aerospace flight target in its forward, lateral, and longitudinal directions, and to evaluate its flight status and maneuverability and other performance.

[0053] Next, the three-dimensional force feature extraction method based on track coordinate system transformation provided by the present invention is further explained with reference to examples.

[0054] In this example, we first simulate the continuous and equally spaced position information of the target in the geocentric coordinate system [x i ,y i ,z i ]、[x j ,y j ,z j ]、[x k ,y k ,z k ], using the track coordinate system to construct expressions (1), (2), (3), and establish a track coordinate system that changes over time. The track coordinate system at the initial moment is as follows: Figure 1 shown.

[0055] Then, the target position information of the simulated motion trajectory [x i ,y i ,z i ], using the velocity calculation expression (4) and the acceleration calculation expression (5), the acceleration of the target in the geocentric coordinate system is obtained The results are as follows Figure 2 shown.

[0056] Result in step 2 It can be written as a three-dimensional acceleration vector Through the coordinate transformation expression (6), the target three-dimensional acceleration vector in the track coordinate system is obtained: That is, the target three-dimensional force characteristics, the results are as follows Figure 3 shown.

[0057] pass Figure 1 It can be seen intuitively that the X-axis (blue line) of the track coordinate system is along the target's flight direction at the current moment. The magnitude of the acceleration value on this axis reflects the magnitude of the target's forward force. A positive value represents the thrust force of the rocket and other forces on the target, and a negative value represents the resistance of the atmosphere and other forces on the target. The Y-axis (red line) of the track coordinate system is perpendicular to the current motion trajectory plane and points to the left. The magnitude of the acceleration value on this axis reflects the magnitude of the target's lateral force. A positive value represents the lateral maneuvering force to the left on the target, and a negative value represents the lateral maneuvering force to the right on the target. The Z-axis (yellow line) of the track coordinate system is perpendicular to the plane formed by the X and Y axes and points upward. The magnitude of the acceleration value on this axis reflects the magnitude of the target's longitudinal force. A positive value represents the upward lift force on the target, and a negative value represents the downward force on the target. These are consistent with the definition of the track coordinate system.

[0058] pass Figure 2 It can be seen intuitively that the X-axis, Y-axis, and Z-axis accelerations of the geocentric system can be used to estimate the track of high-speed flying targets in the atmosphere. However, since the direction of the three-dimensional acceleration in the geocentric system is inconsistent with the target's flight direction, it is difficult to use it to evaluate the target's maneuverability. Figure 2 and Figure 3 It can also be seen from the comparison that although the curves of acceleration in the two coordinate systems are highly similar in trend, due to the differences in the definitions of the two coordinate systems, there are many differences in the specific values ​​on the curves.

[0059] pass Figure 3 It can be seen intuitively that the forward acceleration, that is, the numerical curve of the X-axis of the track coordinate system, has a maximum value of 239, which is the maximum thrust characteristic of the target booster rocket, etc.; the minimum value is -23, which is the maximum resistance characteristic of the target. The lateral acceleration, that is, the numerical curve of the Y-axis of the track coordinate system, has a maximum value of 15, which is the maximum lateral maneuvering force characteristic to the left suffered by the target structure; its minimum value is -32, which is the maximum lateral maneuvering force characteristic to the right suffered by the target structure. The longitudinal acceleration, that is, the numerical curve of the Z-axis of the track coordinate system, has a maximum value of 30, which is the maximum upward lift characteristic suffered by the target structure; its minimum value is -22, which is the maximum downward force characteristic suffered by the target structure. These force characteristic values ​​in three dimensions represent the directional maneuverability of high-speed flying targets in the atmosphere, and can be used as indicators for evaluating the maneuverability characteristics of the target, verifying the effectiveness of the method provided by the present invention.

[0060] Finally, it should be noted that the features mentioned and / or shown in the above description of the exemplary embodiments of the present invention may be combined in the same or similar manner into one or more other embodiments, combined with the features in other embodiments or substituted for the corresponding features in other implementations. The technical solutions obtained by these combinations or substitutions shall also be deemed to be included in the protection scope of the present invention.

Claims

1. A three-dimensional force feature extraction method based on track coordinate system transformation, characterized in that: The following steps are involved: Step 1: Establish a track coordinate system that changes over time: In the formula, and are the three-dimensional position vectors of the high-speed flying target in the atmosphere at three consecutive and equally spaced moments i, j, and k in the launch coordinate system, the station coordinate system, or the geocentric coordinate system, respectively. and are the unit vectors of the X-axis, Y-axis and Z-axis of the track coordinate system respectively; Step 2: Use the second-order 21-point least squares method to perform center smoothing and extract the velocity from the motion estimation data: In the formula, is the velocity in any dimension at the middle moment j of 21 o'clock, h is the sampling interval of position data, w i is the speed coefficient, w i =(n-11) / 770, n=1,2,…,21,p i is any dimensional position; Step 3, use the second-order 21-point least squares method to perform center smoothing and extract the acceleration from the extracted velocity data: In the formula, is the acceleration in any dimension at the middle moment j of 21 o'clock, m is the time interval of velocity data, q i is the acceleration coefficient, q i =(n-11) / 770,n=1,2,…,21,v i is the velocity in any dimension; Step 4: Based on the extracted acceleration, use coordinate transformation to calculate the target three-dimensional acceleration vector in the established track coordinate system. Three-dimensional force characteristics with three-dimensional acceleration vector as the target:

2. The three-dimensional force feature extraction method based on track coordinate system transformation according to claim 1 is characterized in that: The forward acceleration represents the thrust or drag characteristics of the target, the lateral acceleration represents the lateral maneuvering force characteristics of the target, and the longitudinal acceleration represents the lift or lowering force characteristics of the target.

3. The three-dimensional force feature extraction method based on track coordinate system transformation according to claim 2 is characterized in that: When the forward acceleration is a positive value, it indicates the thrust characteristics of the target, and when the forward acceleration is a negative value, it indicates the resistance characteristics of the target; when the lateral acceleration is a positive value, it indicates the leftward maneuvering force characteristics of the target, and when the lateral acceleration is a negative value, it indicates the rightward maneuvering force characteristics of the target; When the longitudinal acceleration is a positive value, it indicates the lift characteristics of the target, and when the lateral acceleration is a negative value, it indicates the downforce characteristics of the target.

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