Cube satellite size estimation method and apparatus based on RCS data

Abstract

The application discloses a kind of based on RCS data's CubeSat size estimation method and device, method includes: the spatial position data of CubeSat is handled, the attitude angle data of satellite is calculated;Using CubeSat RCS data, the attitude angle data obtained by calculation is corrected;Using the CubeSat size estimation method under the three-axis stable state proposed in this paper, the two side lengths of CubeSat are calculated, so as to realize the size estimation of CubeSat.The device is used to realize the above-mentioned method.The application improves the accuracy of CubeSat size estimation based on RCS data, and provides a new scheme for satellite size estimation.

Description

Technical Field

[0001] The present invention relates to the field of using RCS data to carry out on-orbit satellite size estimation, and in particular to a cube satellite size estimation method and device based on RCS data. Background Art

[0002] When using RCS data to estimate the size of in-orbit satellites, the traditional method is to treat the satellite as an ellipsoid and then use the characteristics of the ellipsoidal structure to estimate the satellite's size. This estimation method is relatively simple and crude, and does not consider the satellite's structural characteristics. It is mainly suitable for satellites with structures close to ellipsoids or spheres. Therefore, this method has significant limitations in practical applications. Summary of the Invention

[0003] The object of the present invention is to provide a method and device for estimating the size of a cube satellite based on RCS data.

[0004] The technical solution for achieving the purpose of the present invention is: a method for estimating the size of a cube satellite based on RCS data, comprising the following steps:

[0005] Step 1: Process the CubeSat spatial position data and calculate the satellite's attitude angle data;

[0006] Step 2: Use the CubeSat RCS data to correct the calculated attitude angle data;

[0007] Step 3: Utilize the cube satellite size estimation method under the three-axis stable state to calculate the two side lengths of the cube satellite, thereby realizing the size estimation of the cube satellite.

[0008] Step 1 processes the CubeSat spatial position data and calculates the satellite's attitude angle data. This involves converting the satellite's spatial position data into the satellite's attitude angle data. The specific algorithm is as follows:

[0009] Let (x, y, z) be the position coordinates of the satellite in the J2000 mean equatorial geocentric coordinate system measured by the measuring device at time t, (dx, dy, dz) be the velocity vector coordinates of the satellite in the J2000 mean equatorial geocentric coordinate system measured by the measuring device at time t, (x r ,y r , z r ) is the coordinate of the measuring device at time t in the J2000 mean equatorial geocentric coordinate system.

[0010] The satellite's axis to the Earth is the Z axis, the satellite's on-orbit motion direction is the X axis, and the other direction determined by the right-hand rule is the Y axis. The satellite's body coordinate system is constructed. The satellite's body coordinate system at time t can be expressed as follows under J2000:

[0011]

[0012] Among them, Axis x Represents the unit vector direction of the X-axis of the satellite's coordinate system, Axis y Represents the unit vector direction of the Y axis of the satellite's coordinate system, Axis z Represents the unit vector direction of the Z axis of the satellite body coordinate system;

[0013] Vector D of the direction of the electromagnetic wave reflected by the satellite to the measurement equipment r It can be expressed as:

[0014] D r =(x r -x,x r -y,x r -z)

[0015] The attitude angle (θ, φ) of the satellite in the direction of observation of the measuring device at time t can be expressed as:

[0016]

[0017] In this way, the satellite attitude angle data at each observation moment can be calculated in sequence.

[0018] This step converts the satellite's on-orbit position data into satellite attitude angle data, which makes it easier to associate features with the satellite's RCS data, facilitating the implementation of subsequent steps.

[0019] Step 2 uses the CubeSat RCS data to correct the calculated attitude angle data. This involves using the satellite RCS data features to correct the satellite attitude angle data. The specific method is as follows:

[0020] The CubeSat's RCS maximum should be achieved when a plane of the CubeSat faces the measurement device. The corresponding pitch angle at this location should be 0°. When correcting the attitude angle data, first find the pitch angle θ0 corresponding to the RCS maximum in the RCS sequence. Then, reduce the pitch angle sequence values ​​calculated in the previous step by θ0, so that the pitch angle corresponding to the RCS maximum is 0°.

[0021] In this way, the corrected satellite attitude angle data can be obtained.

[0022] This step uses the characteristic points (maximum points) of the RCS sequence to correct the satellite attitude angle data, so that a more accurate correlation is formed between the satellite attitude angle data and the RCS sequence, which can make subsequent size estimation more accurate.

[0023] Step 3 uses the cube satellite size estimation method under the three-axis stable state to calculate the two side lengths of the cube satellite, thereby realizing the size estimation of the cube satellite. The method involves the cube satellite size estimation method under the three-axis stable state. The specific method is as follows:

[0024] The CubeSat is composed of six rectangular plates. When the attitude angles are arbitrary θ and φ, the RCS of a perfect conductive rectangular plate can be approximately expressed as:

[0025]

[0026] Where a and b represent the length and width of the rectangular plate, λ represents the wavelength of the electromagnetic wave of the measuring device, and k = 2π / λ;

[0027] When the pitch angle θ is 0°, RCS reaches its maximum value max(RCS), that is:

[0028]

[0029] When θ and φ satisfy |aksinθcosφ|=n*π or |bksinθsinφ|=n*π (n>0), RCS obtains the lowest value point in the area; if n=1, an extreme low point is obtained on the left and right of the RCS maximum value point, and the corresponding attitude angles are recorded as (θ l ,φ l ) and (θ r ,φ r ), then one of the following formulas is satisfied:

[0030]

[0031] or

[0032]

[0033] Formula (3) can be used to calculate a set of a values ​​(a1, a2), and combined with formula (2) to obtain a corresponding set of b values ​​(b1, b2), namely:

[0034]

[0035] Using formula (4), we can calculate a set of b values ​​(b3, b4), and combining it with formula (2), we can get the corresponding set of a values ​​(a3, a4), namely:

[0036]

[0037] The mean values ​​of the two groups of satellite sizes (A1, B1) and (A2, B2) calculated by formula (3) and formula (4) are:

[0038]

[0039] The standard deviation of the two sets of satellite size mean results is:

[0040]

[0041] The minimum value of the sum of the coefficients of variation is used to determine the final value. The sum of the coefficients of variation corresponding to the two sets of results is:

[0042]

[0043] Compare the sizes of C1 and C2: When the C1 value is smaller, the first set of results (A1, B1) is the final size of the CubeSat; when the C2 value is smaller, the second set of results (A2, B2) is the final size of the CubeSat.

[0044] In this way, the size estimation of the CubeSat is completed.

[0045] This step selects two RCS data minimum points, one to the left and one to the right of the maximum, as eigenvalue points. Using the formulas for these two eigenvalue points, we calculate two different sets of size estimates. We then use the coefficient of variation and the correlation between the data to determine the better estimate, which we then use as the final satellite size estimate. This approach ensures more reasonable and accurate estimates.

[0046] A device for estimating the size of a cube satellite based on RCS data, comprising:

[0047] The satellite attitude angle data calculation module is used to process the CubeSat spatial position data to obtain the satellite attitude angle data;

[0048] The satellite attitude angle data correction module uses the cube satellite RCS data to correct the satellite attitude angle data to obtain the corrected satellite attitude angle data;

[0049] The cube satellite size estimation module uses the cube satellite size estimation method under the three-axis stable state to calculate the two side lengths of the cube satellite and estimate the size of the cube satellite.

[0050] Compared with the existing technology, the present invention has the following significant advantages: 1) a satellite attitude angle calculation module is added, so that the changes in the satellite's visible surface with the viewing angle of the measuring equipment can be expressed through data, and the changes in the satellite attitude angle are integrated into the target size estimation process, thereby improving the effectiveness and accuracy of size estimation; 2) this method limits the research object to cube satellites, which is also the main structural type of most current small and medium-sized satellites, and helps to solve the size estimation problem of most small and medium-sized satellites; 3) an in-depth study is conducted on the size estimation problem of cube satellites, and a cube satellite size estimation method is proposed based on the RCS equivalent formula of cube satellites, which can solve the cube satellite size estimation problem in a targeted manner.

[0051] The present invention is further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 Flowchart of the CubeSat size estimation method based on RCS data;

[0053] Figure 2 A CubeSat built for simulation in one instance;

[0054] Figure 3 is an RCS sequence curve and attitude angle change curve of the cube satellite in the example. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0056] In one embodiment, combined Figure 1 The specific implementation flow chart of the present invention provides a CubeSat size estimation method based on RCS data, including the following steps:

[0057] Step 1: Process the spatial position data of the cube satellite and calculate the satellite's attitude angle data;

[0058] Step 2: Use the CubeSat RCS data to correct the calculated attitude angle data;

[0059] Step 3: Utilize the cube satellite size estimation method under the three-axis stable state to calculate the two side lengths of the cube satellite, thereby realizing the size estimation of the cube satellite.

[0060] Furthermore, in one embodiment, in step 1, the CubeSat spatial position data acquired by the measurement equipment is processed to calculate the attitude angle data within the airspace of the satellite transiting the measurement equipment. The STK satellite analysis tool can be used to simulate the spatial position data of a CubeSat (0.3m*0.3m*0.3m in size) measured by a certain device and calculate the corresponding satellite attitude angle data. The satellite's spatial position data includes the transit time scale, position (x, y, z), and velocity (dx, dy, dz) in the J2000 mean equatorial geocentric coordinate system. Vector analysis methods can be used to calculate the pitch and roll angles of the satellite's attitude in the direction of the measurement equipment's viewing angle. Figure 2 The structural model of the cube satellite is shown. Figure 3 The satellite RCS change curve and the satellite attitude angle data (pitch angle and roll angle) obtained through steps 1 and 2 are displayed.

[0061] Furthermore, in one embodiment, the calculated attitude angle data is corrected in step 2 using the CubeSat RCS data acquired by the measurement equipment, primarily the pitch angle within the attitude angle. First, the maximum value in the RCS data is found. This point theoretically corresponds to a pitch angle of 0°. If the pitch angle corresponding to the RCS maximum is θ, the pitch angle sequence values ​​calculated in the previous step are sequentially reduced by θ to obtain the corrected attitude angle data.

[0062] Furthermore, in one embodiment, a cube satellite size estimation method under a three-axis stable state is used to calculate the two side lengths of the cube satellite, thereby achieving the size estimation of the cube satellite. The cube satellite size estimation method is explained as follows:

[0063] The CubeSat is composed of six rectangular plates. When the attitude angles are arbitrary θ and φ, the RCS of a perfect conductive rectangular plate can be approximately expressed as:

[0064]

[0065] In the above formula, a and b represent the length and width of the rectangular plate, λ represents the wavelength of the electromagnetic wave, and k = 2π / λ.

[0066] When the pitch angle θ is 0°, RCS reaches its maximum value max(RCS), that is:

[0067]

[0068] When θ and φ satisfy |aksinθcosφ|=n*π or |bksinθsinφ|=n*π (n>0), RCS obtains the lowest value point in the area; if n=1, an extreme low point is obtained on the left and right of the RCS maximum value point, and the corresponding attitude angles are recorded as (θl ,φ l ) and (θ r ,φ r ), then one of the following formulas is satisfied:

[0069]

[0070] or

[0071]

[0072] Formula (3) can be used to calculate a set of a values ​​(a1, a2), and combined with formula (2) to obtain a corresponding set of b values ​​(b1, b2), namely:

[0073]

[0074] Using formula (4), we can calculate a set of b values ​​(b3, b4), and combining it with formula (2), we can get the corresponding set of a values ​​(a3, a4), namely:

[0075]

[0076] The mean values ​​of the two groups of satellite sizes (A1, B1) and (A2, B2) calculated by formula (3) and formula (4) are:

[0077]

[0078] The standard deviation of the two sets of satellite size mean results is:

[0079]

[0080]

[0081] The minimum value of the sum of the coefficients of variation is used to determine the final value. The sum of the coefficients of variation corresponding to the two sets of results is:

[0082]

[0083] Compare the sizes of C1 and C2: When the C1 value is smaller, the first set of results (A1, B1) is the final size of the CubeSat; when the C2 value is smaller, the second set of results (A2, B2) is the final size of the CubeSat.

[0084] In this way, the size estimation of CubeSats can be achieved.

[0085] In one embodiment, the electromagnetic frequency emitted by the measurement equipment is 1 GHz, and a cube satellite (size 0.3 m*0.3 m*0.3 m) is detected. The calculated maximum RCS of the satellite is 0.9850 m2, the attitude angle of the extreme low point to the left of the RCS maximum point is (44.24°, -62.45°), and the attitude angle of the extreme low point to the right of the RCS maximum point is (-28.77°, 74.68°). Using the maximum RCS value and the two sets of attitude angle data, the target size estimation results corresponding to formulas (5) and (6) are calculated, as shown in the following table:

[0086]

[0087] Since the coefficient of variation and the value of the sum of the calculated results using formula (6) are the smallest, the mean satellite size calculated using formula (6) (i.e., 0.283m*0.303m) is determined as the final estimated satellite size. This result is consistent with the actual size of a single satellite surface (0.3m*0.3m).

[0088] Furthermore, using a traditional ellipsoidal model size estimation method to process this data, the satellite size was calculated to be 0.171m by 0.488m. Compared to the estimated value in this paper (0.283m by 0.303m), the traditional ellipsoidal model size estimation method yields a poorer result, indicating that the proposed CubeSat size estimation method is more effective.

[0089] In one embodiment, a device for estimating the size of a CubeSat based on RCS data is provided, the device comprising:

[0090] The satellite attitude angle calculation module can process and calculate the satellite's spatial position data to obtain the attitude angle data when the satellite passes;

[0091] The attitude angle correction module can correct the attitude angle data according to the RCS data characteristics;

[0092] The cube satellite size estimation method can estimate the size of the satellite's visible surface based on the RCS data characteristics and attitude angle data, thereby realizing the cube satellite size estimation.

[0093] The specific definition of a CubeSat size estimation device based on RCS data can be found in the definition of a CubeSat size estimation method based on RCS data above and will not be repeated here. Each module in the aforementioned CubeSat size estimation device based on RCS data can be implemented in whole or in part via software, hardware, or a combination thereof. Each of these modules can be embedded in or independent of a processor in a computer device in hardware form, or stored in a computer device memory in software form, allowing the processor to call and execute the corresponding operations of each module.

[0094] This invention provides a CubeSat size estimation method and device based on RCS data. This method uses RCS data to estimate the size of a CubeSat. The device calculates satellite attitude angles based on satellite motion data and RCS data, and uses the CubeSat size estimation method to estimate satellite size, thereby obtaining a CubeSat size estimation result. This invention provides a CubeSat size estimation method that effectively improves the accuracy of CubeSat size estimation results and offers a new approach to space satellite size estimation.

[0095] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only illustrative of the principles of the present invention. Without departing from the spirit and scope of the present invention, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A cube satellite size estimation method based on RCS data, characterized in that: The following steps are involved: Step 1: Process the CubeSat spatial position data to obtain the satellite's attitude angle data; Step 2: Using the CubeSat RCS data, the satellite attitude angle data obtained in step 1 is corrected to obtain the corrected satellite attitude angle data, specifically including: In the CubeSat RCS data, the position of the RCS maximum is when one of the CubeSat planes faces the direction of the measurement equipment, and the corresponding pitch angle at this position should be 0°; When correcting the attitude angle data, first find the pitch angle θ0 corresponding to the RCS maximum value in the CubeSat RCS data, then reduce the pitch angle in the satellite attitude angle data obtained in step 1 by θ0, so that the pitch angle corresponding to the RCS maximum position is 0°, and obtain the corrected satellite attitude angle data; Step 3: Using the cube satellite size estimation method under the three-axis stable state, calculate the two side lengths of the cube satellite to complete the size estimation of the cube satellite, which specifically includes: The CubeSat is composed of six rectangular plates. When the attitude angles are arbitrary θ and φ, the RCS of a perfect conductive rectangular plate can be approximately expressed as: Where a and b represent the length and width of the rectangular plate, λ represents the wavelength of the electromagnetic wave of the measuring device, and k = 2π / λ; When the pitch angle θ is 0°, RCS reaches its maximum value max(RCS), that is: When θ and φ satisfy |aksinθcosφ|=n*π or |bksinθsinφ|=n*π, n>0, RCS obtains the lowest value point in the area; if n=1, an extreme low point is obtained on the left and right of the RCS maximum value point, and the corresponding attitude angles are recorded as (θ l ,φ l ) and (θ r ,φ r ), then one of the following formulas is satisfied: or Formula (3) is used to calculate a set of a values ​​(a1, a2), and combined with formula (2) to obtain a corresponding set of b values ​​(b1, b2), namely: Using formula (4) to calculate a set of b values ​​(b3, b4), combined with formula (2) to obtain the corresponding set of a values ​​(a3, a4), namely: The mean values ​​of the two groups of satellite sizes (A1, B1) and (A2, B2) calculated by formula (3) and formula (4) are: The standard deviation of the two sets of satellite size mean results is: The minimum value of the sum of the coefficients of variation is used to determine the final value. The sum of the coefficients of variation corresponding to the two sets of results is: Compare the sizes of C1 and C2: When the C1 value is smaller, the first set of results (A1, B1) is the final size of the CubeSat; when the C2 value is smaller, the second set of results (A2, B2) is the final size of the CubeSat. In this way, the size estimation of the CubeSat is completed.

2. The CubeSat size estimation method based on RCS data according to claim 1, characterized in that: In step 1, the CubeSat spatial position data is processed to calculate the satellite's attitude angle data, including: Let (x, y, z) be the position coordinates of the satellite in the J2000 mean equatorial geocentric coordinate system measured by the measuring device at time t, (dx, dy, dz) be the velocity vector coordinates of the satellite in the J2000 mean equatorial geocentric coordinate system measured by the measuring device at time t, (x r ,y r , z r ) is the coordinate of the measuring device at time t in the J2000 mean equatorial geocentric coordinate system; The satellite's axis to the Earth is the Z axis, the satellite's on-orbit motion direction is the X axis, and the other direction determined by the right-hand rule is the Y axis. The satellite's body coordinate system is constructed. The satellite's body coordinate system at time t is expressed in J2000 as follows: Among them, Axis x Represents the unit vector direction of the X-axis of the satellite's coordinate system, Axis y Represents the unit vector direction of the Y axis of the satellite's coordinate system, Axis z Represents the unit vector direction of the Z axis of the satellite body coordinate system; Vector D of the direction of the electromagnetic wave reflected by the satellite to the measurement equipment r Expressed as: D r =(x r -x,x r -y,x r -z) The attitude angle (θ, φ) of the satellite in the direction of observation of the measuring device at time t is expressed as: Calculate the satellite attitude angle data at each observation moment; The satellite attitude angle data at each observation time forms the satellite attitude angle data.

3. A CubeSat size estimation device based on RCS data for implementing the method of claim 1 or 2, characterized in that: include: The satellite attitude angle data calculation module is used to process the CubeSat spatial position data to obtain the satellite attitude angle data; The satellite attitude angle data correction module uses the cube satellite RCS data to correct the satellite attitude angle data to obtain the corrected satellite attitude angle data; The cube satellite size estimation module uses the cube satellite size estimation method under the three-axis stable state to calculate the two side lengths of the cube satellite and estimate the size of the cube satellite.

Images