A method for measuring distance and velocity of space targets using space-based radar optical composite

Abstract

The present invention provides a method for measuring the distance and velocity of space targets using a space-based radar optical composite. First, for relative measurement of space targets, a theoretical analysis is performed based on the target's relative acceleration in a relative measurement coordinate system, and the quantitative mapping relationship between the target's relative jerk, relative acceleration, relative distance, and relative velocity is obtained. Then, the method uses guidance information from optical angle measurement to reduce the dimensionality of search parameters, and then performs long-term coherent accumulation. Compared with traditional search methods, the present invention achieves dimensionality reduction of high-dimensional parameters, significantly reduces the amount of computation, is more adaptable to the working conditions of space-based platforms with limited computing power, and can be directly applied in engineering projects.

Description

Technical Field

[0001] The present invention belongs to the field of radar measurement technology, and in particular relates to a method for measuring the distance and speed of a space-based radar optical composite space target. Background Art

[0002] With the rapid development of aerospace technology, human beings' ability to enter and utilize space is constantly increasing. Space-based radar uses satellites as observation platforms to detect space targets and complete tasks such as search, tracking, positioning and measurement.

[0003] To achieve precise on-orbit detection of satellites, constructing a relative measurement model based on the equations of motion of orbiting targets is a prerequisite for measurement algorithm design. In their article "Satellite Maneuver Detection using Two-Line Element Data," published in the 9th issue of the Advanced Maui Optical and Space Surveillance Technologies Conference in 2007, Kelecy et al. proposed segmenting the target satellite's two-line orbital elements (TLEs) and performing polynomial fitting, then recursively calculating the predicted difference to detect space targets. However, since space targets' echoes are typically weak and their relative motion is highly dynamic, this method introduces significant measurement errors. In their article "Radar Maneuvering Target Motion Estimation Based on Generalized Radon-Fourier Transform," published in the IEEE Transactions on Signal Processing in December 2012, Jia Xu et al. proposed a parameter estimation method using maximum likelihood estimation. However, this method requires a four-dimensional search of range, velocity, acceleration, and jerk, which is computationally intensive.

[0004] In summary, existing TLE-based detection methods often suffer from time lags and large estimation errors. Existing detection methods for highly dynamic and faint targets require multi-dimensional searches of spatial targets, which is computationally intensive. Summary of the Invention

[0005] To solve the above problems, the present invention provides a method for measuring the distance and velocity of space targets using optical composite space radar. The method derives a target relative motion model under optical guidance, and then uses dimensionality reduction parameter search to measure distance and velocity under optical guidance, which greatly reduces the amount of calculation.

[0006] A method for measuring distance and velocity of space targets using a space-based radar optical composite system comprises the following steps:

[0007] S1: According to the generalized random Fourier transform algorithm, the coherent accumulation result of the target echo signal is obtained in the discrete form of the third-order generalized random Fourier transform expression ,in, The first target within the set relative distance search range between the radar and the target The relative distance corresponding to the search points, The first target in the target speed search range The speed corresponding to the search point;

[0008] S2: Use the maximum likelihood estimation method to construct The objective function , and then solve the objective function to get the target distance measurement value and speed measurements ;

[0009] S3: According to the target distance measurement value and speed measurements Get target acceleration and jerk :

[0010]

[0011]

[0012] in, is the target velocity prior value calculated from the target orbit parameters, Indicates fast time.

[0013] Furthermore, the third-order generalized random Fourier transform expression is The formula is:

[0014]

[0015] in, , is the distance search range, is the minimum relative distance between the radar and the target, is the maximum relative distance between the radar and the target, ,in Indicates the distance search point index, is the distance search step; , is the speed search range, is the minimum speed of the target, is the maximum speed of the target, ,in Indicates the speed search point index, Search step size for speed; Search range for the target's set acceleration The first The acceleration corresponding to the search point, and , and have , is the minimum acceleration of the target, is the maximum acceleration of the target, where Indicates the acceleration search point index, Search step size for acceleration; Search range for the set jerk at the target The first The acceleration corresponding to the search point, and , and have , is the minimum jerk of the target, is the maximum jerk of the target, where Indicates the acceleration search point index, Search step size for jerk; is the pulse period, Indicates the periodic number of the target echo signal, Indicates the total number of target echo signal cycles and the distance gate width , is the speed of light, is the distance sampling rate, is the rounding function, Phase compensation function to achieve pulse coherent accumulation.

[0016] Furthermore, the phase compensation function The calculation formula is as follows:

[0017]

[0018] in, Indicates plural, Indicates the wavelength of the target echo signal.

[0019] Furthermore, for the minimum relative distance , the radial velocity search range of the target is:

[0020]

[0021] in, The minimum relative distance The radial velocity search lower limit is The minimum relative distance The upper limit of radial velocity search under 、 、 are all set coefficients, and , , ,in, and are two orthogonal unit vectors in the intersection circle of the radar equidistant step projection sphere and the target position error sphere, represents the coordinates of the center of the intersecting section circle, is the parameter of the intersecting section circle in polar coordinates, is the polar axis, is the polar angle; is the position coordinate of the radar in the geocentric coordinate system, is the relative speed between the radar and the target in the observation coordinate system established with the radar as the center;

[0022] For the maximum relative distance , the radial velocity search range of the target is:

[0023]

[0024] in, The maximum relative distance The radial velocity search lower limit is The maximum relative distance The upper limit of the radial velocity search is given below.

[0025] Furthermore, for the minimum relative distance , the target's tangential velocity search range is:

[0026]

[0027] in, The minimum relative distance The lower limit of the tangential velocity search is The minimum relative distance The upper limit of the tangential velocity search under is the relative speed between the radar and the target in the observation coordinate system established with the radar as the center;

[0028] For the maximum relative distance , the target's tangential velocity search range is:

[0029]

[0030] in, The maximum relative distance The lower limit of the tangential velocity search is The maximum relative distance The upper limit of the tangential velocity search is given below.

[0031] Furthermore, for the minimum relative distance , the radial acceleration search range of the target is:

[0032]

[0033] in, The minimum relative distance The search lower limit of radial acceleration under The minimum relative distance The search upper limit of radial acceleration under is the current relative distance between the radar and the target;

[0034] For the maximum relative distance , the radial acceleration search range of the target is:

[0035]

[0036] in, The maximum relative distance The search lower limit of radial acceleration under The maximum relative distance The search upper limit for the radial acceleration under .

[0037] Furthermore, the target radial acceleration at different relative distances The expression is:

[0038]

[0039] in, is the current relative speed between the radar and the target in the observation coordinate system established with the radar as the center, is the current radial velocity of the target in the observation coordinate system established with the radar as the center, is the current relative distance between the radar and the target.

[0040] Furthermore, the target acceleration at different relative distances The expression is:

[0041]

[0042] in, is the current relative speed The relative acceleration between the radar and the target under is the current relative distance The target radial acceleration under is the current relative speed between the radar and the target in the observation coordinate system established with the radar as the center, is the current relative distance between the radar and the target.

[0043] Beneficial effects:

[0044] The present invention provides a method for measuring the distance and velocity of space targets using a space-based radar optical composite. First, for relative measurement of space targets, a theoretical analysis is performed based on the target's relative acceleration in a relative measurement coordinate system, and the quantitative mapping relationship between the target's relative jerk, relative acceleration, relative distance, and relative velocity is obtained. Then, the method uses guidance information from optical angle measurement to reduce the dimensionality of search parameters, and then performs long-term coherent accumulation. Compared with traditional search methods, the present invention achieves dimensionality reduction of high-dimensional parameters, significantly reduces the amount of computation, is more adaptable to the working conditions of space-based platforms with limited computing power, and can be directly applied in engineering projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 A flow chart of a method for measuring distance and velocity of space targets using a space-based radar optical composite is provided by the present invention;

[0046] Figure 2 The relative measurement coordinate system provided by the present invention;

[0047] Figure 3 A schematic diagram of radar search and distance error provided by the present invention;

[0048] Figure 4 A flowchart of the theoretical analysis of the quantitative mapping relationship provided by the present invention;

[0049] Figure 5 A schematic diagram of acceleration changing with distance provided by the present invention;

[0050] Figure 6 This is a schematic diagram of the change of acceleration with distance provided by the present invention. DETAILED DESCRIPTION

[0051] In order to enable people skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0052] Specifically, such as Figure 1 As shown, a method for measuring distance and velocity of space targets by space-based radar optical composite includes the following steps:

[0053] S1: According to the generalized random Fourier transform algorithm, the coherent accumulation result of the target echo signal is obtained in the discrete form of the third-order generalized random Fourier transform expression ,in, The first target within the set relative distance search range between the radar and the target The relative distance corresponding to the search points, The first target in the target speed search range The speed corresponding to the search point;

[0054] S2: Use the maximum likelihood estimation method to construct The objective function , and then solve the objective function to get the target distance measurement value and speed measurements ;

[0055] S3: According to the target distance measurement value and speed measurements Get target acceleration and jerk :

[0056]

[0057]

[0058] in, is the target velocity prior value calculated from the target orbit parameters, Indicates fast time.

[0059] The recursive relationship between target distance and speed, acceleration, and jerk is derived in detail below to prove that the present invention can calculate speed, acceleration, and jerk through target distance.

[0060] Step 1: Analyze the error range of the distance target motion parameters

[0061] In actual detection, it is usually necessary to use methods such as ground measurement to measure the orbital parameters of space targets and obtain the relative prior information of the target. However, there are usually errors in the orbital parameters, which also causes the prior position of the target to be an error sphere. In order to analyze the error range of the target motion parameters, it is necessary to describe the relative motion state of the high-dynamic target in space and the radar. First, an observation coordinate system is established with the observation radar as the center, such as Figure 2 As shown, is the radial velocity of the target, is the tangential velocity of the target, represents the relative speed, Indicates relative distance. With the help of high-precision target angle information obtained by optical sensing, the direction vector pointing from the radar to the target can be obtained. , let this direction be radial. The radial velocity is obtained by projecting radially and tangentially , tangential velocity , where the radial velocity expression is:

[0062] (1)

[0063] The relationship between radial velocity and tangential velocity is as follows:

[0064] (2)

[0065] The acceleration expression is:

[0066] (3)

[0067] like Figure 3 As shown in , the position coordinates of the radar in the geocentric coordinate system are , relative speed , the target-radar line and the cross-sectional position of the two balls are , then the radial velocity is (Relative speed in radial projection)

[0068] Since the intersection of the radar equidistant step projection sphere and the target position error sphere is a circle, we can use polar coordinates to convert Parameterized as

[0069] (4)

[0070] in and are two orthogonal unit vectors within the cross-section circle, represents the coordinates of the center of the cross-section circle, is the parameter in polar coordinates. Then the radial velocity can be expressed as

[0071] (5)

[0072] in, .

[0073] It is not difficult to find that for the minimum distance , the radial velocity search range is:

[0074] (6)

[0075] For the maximum distance , then the radial velocity search range is:

[0076] (7)

[0077] According to the relationship between tangential velocity and radial velocity in (2), it can be seen that when the radial velocity is maximum, the tangential velocity is minimum; and when the radial velocity is minimum, the tangential velocity is maximum. The range of tangential velocity can be obtained:

[0078] (8)

[0079] According to formula (3), the maximum and minimum values ​​of radial acceleration can be obtained, namely:

[0080] (9)

[0081] It can be seen that when the search relative distance is When the target is , the radial acceleration search range is .

[0082] Step 2: Range error sphere projection based on optical guidance

[0083] When using space-based radar to detect targets, the intersection of the radar's equidistant step projection sphere and the target's orbital parameter error sphere is a circle. Under optical guidance, angle measurement is extremely accurate. Therefore, we only need to consider one point on the intersection of the two spheres, that is, the intersection of the line connecting the radar and the target position and the interface, as shown in the figure. Figure 3 As shown in .

[0084] Step 3: Narrowing the speed error range based on optical guidance

[0085] In practical applications, the prior information of the relative distance and relative velocity of the two stars can be obtained by predicting the orbital parameters of the target star. In the space-based radar optical composite scenario, the platform optical sensor is usually used to measure the target angle, and the radar is used to measure the distance and velocity. Under optical guidance, we only need to consider a point on the cross section determined by the intersection of the radar equidistant step projection sphere and the target position orbit parameter error sphere. That is, in formula (4) The coordinates are only related to the radius of the radar's equidistant stepped projection sphere.

[0086] In the expression of radial velocity in formula (5), and Equivalent, that is, the parameters in polar coordinates are , then (10)

[0087] There are , it is not difficult to see that the search range of speed and The point coordinate correspondence is equivalent to the one-to-one correspondence between the speed search range and the distance search range.

[0088] Step 4: Narrowing the Acceleration Error Range Based on Optical Guidance

[0089] From formula (3), we can know that the target radial acceleration can be obtained from the tangential velocity Relative distance The tangential velocity and radial velocity satisfy the constraint relationship of formula (2), so the radial velocity can be used to determine the different search distances. Downward acceleration However, due to the errors in orbital parameters, the possible positions of the target star form an error sphere in space. With the help of high-precision angle measurement information from space-based optics, the orbital parameter guidance error range can be corrected. The corrected search area is only a line segment at this angle within the sphere. At the same time, the radial velocity of the target in this area is .

[0090] From this we can deduce different search distances The target radial acceleration expression under is:

[0091] (11)

[0092] In the formula is the relative velocity modulus, is the unit vector in the direction of the target.

[0093] Therefore, under optical guidance, the relative distance is known , radial acceleration It is a fixed value and does not need to be searched.

[0094] Step 5: Analyze the jerk error range based on optical guidance

[0095] Radial acceleration Differentiating the jerk gives the following expression:

[0096] (12)

[0097] Expanding the above formula, we can get

[0098] (13)

[0099] And there is

[0100] (14)

[0101] Substituting formula (14) into formula (13), we can obtain:

[0102] (15)

[0103] Also because

[0104] (16)

[0105] Then we can substitute equations (15) and (16) into (12) to obtain the following expression for the jerk:

[0106] (17)

[0107] in Represents the differential of the relative velocity between the target star and our star, that is, the relative acceleration.

[0108] Assume there is acceleration According to formula (3), we know that at this point is also determined according to the following velocity vector relationship:

[0109] (18)

[0110] We can also know Substituting equations (3) and (18) into equation (17) yields the jerk expression:

[0111] (19)

[0112] Considering the first term in the above formula, it is not difficult to find that for a certain known speed and the determined unknown relative acceleration , both with relative distance Regardless, the radius is The sphere is the target a priori position error sphere (such as Figure 3 On the surface intercepted by Therefore, according to formula (19), each acceleration value corresponds to a unique jerk value, thus achieving search dimensionality reduction.

[0113] Therefore, under the optical guidance condition, high-precision target angle information can be obtained. When the target is , the radial acceleration and radial jerk are both fixed values ​​and there is no need to search for them.

[0114] Step 6: Perform maximum likelihood estimation based on the above dimensionality reduction parameter method

[0115] Assume that the transmitted signal of the nth cycle is ,in For slow time, is the pulse period, For fast time, the target echo signal can be modeled as:

[0116] (20)

[0117] In the formula Indicates the echo signal amplitude (including target reflection characteristics), represents the time delay (related to the target distance R), Representative noise (usually assumed to be additive white Gaussian noise)

[0118] The echo signal is coherently accumulated, and the coherent accumulation result is used as the likelihood function, which can be expressed as

[0119] (twenty one)

[0120] In the formula , is the speed of light, Phase compensation function to achieve pulse coherent accumulation.

[0121] The estimated values ​​of each parameter can be obtained based on the likelihood function. The specific process is as follows:

[0122] (twenty two)

[0123] In the formula The estimated results are the initial radial distance, radial velocity, radial acceleration and radial jerk. MLE provides a theoretical framework for parameter estimation through model matching.

[0124] According to the generalized RFT (GRFT) algorithm, the present invention can derive the third-order GRFT expression in discrete form as follows:

[0125] (twenty three)

[0126] in, , is the distance search range, is the minimum relative distance between the radar and the target, is the maximum relative distance between the radar and the target, ,in Indicates the distance search point index, is the distance search step; , is the speed search range, is the minimum speed of the target, is the maximum speed of the target, ,in Indicates the speed search point index, Search step size for speed; Search range for the target's set acceleration The first The acceleration corresponding to the search point, and , and have , is the minimum acceleration of the target, is the maximum acceleration of the target, where Indicates the acceleration search point index, Search step size for acceleration; Search range for the set jerk at the target The first The acceleration corresponding to the search point, and , and have , is the minimum jerk of the target, is the maximum jerk of the target, where Indicates the acceleration search point index, Search step size for jerk; is the pulse period, Indicates the periodic number of the target echo signal, Indicates the total number of target echo signal cycles and the distance gate width , is the speed of light, is the distance sampling rate, is the rounding function, To realize the phase compensation function of pulse coherent accumulation, .

[0127] When the distance template is , speed template is When, because of different search distances Acceleration under and jerk It has been given and there is no need to search for it, so formula (23) can be rewritten as:

[0128] (twenty four)

[0129] From formula (24), we can see that when the search distance ,speed , acceleration , acceleration When they match the target's true distance, velocity, acceleration, and jerk respectively, the energy of all echo pulses can be gathered together to achieve coherent accumulation, and ultimately obtain the target distance and velocity parameters.

[0130] According to the MLE method, the measurement results of target distance and speed can be obtained:

[0131] (25)

[0132] According to equations (11) and (19), the measurement results of target acceleration and jerk can be obtained:

[0133] (26)

[0134] (27)

[0135] Furthermore, if Figure 4 As shown, the present invention proposes a low-computing-power, high-precision measurement method for distance and speed of high-dynamic targets using space-based radar optical composite. This method achieves distance and speed measurement under low-computing-power conditions through the target relative motion model under optical guidance and the parameter search algorithm of the method of the present invention.

[0136] In this embodiment, our satellite approaches the target satellite at a distance of 50km and measures the relative distance and velocity parameters of the two satellites. Figure 3 This paper demonstrates how a space-based radar searches for the target satellite under optical guidance. The specific simulation parameters are as follows:

[0137]

[0138] First, using orbital parameter guidance, we determine the relative distance between the two satellites to be 50 km, with an error of 5 km. The target satellite's possible positions form an error sphere in space, with a center 50 km from the target satellite and a radius of 5 km. High-precision angular information obtained by optical sensing is used to further correct the orbital parameter error guidance error range. Since the typical error of space-based optical angular measurement is 0.01°, the lateral positioning error at a distance of 50 km is only 8.7 meters, which can be ignored in this embodiment.

[0139] By using the dimensionality reduction parameter search method proposed in this invention, by real-time calculation of the acceleration and jerk values ​​at different search distances, only two-dimensional searches of distance and speed are required to achieve high-precision parameter estimation at a low computing cost. Figure 5 As shown, the acceleration parameter changes as Figure 6 shown.

[0140] Using the parameters shown in the table above, we calculate the computational complexity of the traditional parameter search algorithm and the dimensionality reduction parameter search algorithm (the computational complexity is measured by the number of real number multiplications), and obtain the following results.

[0141]

[0142] As shown in the above table, the total computational complexity is reduced by 24084 times. It can be concluded that the dimensionality reduction parameter search method proposed in the present invention can significantly reduce the computational complexity and realize high-precision distance and velocity parameter measurement in real time on a space-based platform with limited computing power.

[0143] In summary, the method for measuring the distance and velocity of space targets using optical composite space radars provided by the present invention is a low-computing-power, high-precision method for measuring the distance and velocity of space targets using optically guided motion parameter dimensionality reduction search. Compared with traditional precision ranging and velocity measurement algorithms based on four-dimensional parameter searches of distance, velocity, acceleration, and jerk, the present invention takes into account various constraints of the space-based platform (computing power constraints, power consumption limitations, storage resource limitations, etc.), and combines the accuracy of angle measurement using optical detection to design a set of dimensionality reduction parameter search methods under optical guidance, which greatly reduces the amount of computation. The method is suitable for high-precision, low-computing-power measurement of the distance and velocity of highly dynamic targets in space-based radar optical composite scenarios, and can be directly applied in engineering.

[0144] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may of course make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for measuring distance and velocity of space targets using a space-based radar optical composite, characterized in that: The following steps are involved: S1: According to the generalized random Fourier transform algorithm, the coherent accumulation result of the target echo signal is obtained in the discrete form of the third-order generalized random Fourier transform expression ,in, The first target within the set relative distance search range between the radar and the target The relative distance corresponding to the search points, The first target in the target speed search range The speed corresponding to the search point; S2: Use the maximum likelihood estimation method to construct The objective function , and then solve the objective function to get the target distance measurement value and speed measurements ; S3: According to the target distance measurement value and speed measurements Get target acceleration and jerk : in, is the target velocity prior value calculated from the target orbit parameters, Indicates fast time.

2. The method for measuring distance and velocity of a space-based radar optical composite space target according to claim 1, wherein: The third-order generalized random Fourier transform expression The formula is: in, , is the distance search range, is the minimum relative distance between the radar and the target, is the maximum relative distance between the radar and the target, ,in Indicates the distance search point index, is the distance search step; , is the speed search range, is the minimum speed of the target, is the maximum speed of the target, ,in Indicates the speed search point index, Search step size for speed; Search range for the target's set acceleration The first The acceleration corresponding to the search point, is the minimum acceleration of the target, is the maximum acceleration of the target; Search range for the set jerk at the target The first The acceleration corresponding to the search point, is the minimum jerk of the target, is the maximum jerk of the target; is the pulse period, Indicates the periodic number of the target echo signal, Indicates the total number of target echo signal cycles and the distance gate width , is the speed of light, is the distance sampling rate, is the rounding function, Phase compensation function to achieve pulse coherent accumulation.

3. The method for measuring distance and velocity of a space-based radar optical composite space target according to claim 2, wherein: Phase compensation function The calculation formula is as follows: in, Indicates plural, Indicates the wavelength of the target echo signal; Search range for the target's set acceleration The first The acceleration corresponding to the search point, and , and have , is the minimum acceleration of the target, is the maximum acceleration of the target, where Indicates the acceleration search point index, Search step size for acceleration; Search range for the set jerk at the target The first The acceleration corresponding to the search point, and , and have , is the minimum jerk of the target, is the maximum jerk of the target, where Indicates the acceleration search point index, The jerk search step size.

4. The method for measuring distance and velocity of a space-based radar optical composite space target according to claim 2, wherein: For the minimum relative distance , the radial velocity search range of the target is: in, The minimum relative distance The radial velocity search lower limit is The minimum relative distance The upper limit of radial velocity search under 、 、 are all set coefficients, and , , ,in, and are two orthogonal unit vectors in the intersection circle of the radar equidistant step projection sphere and the target position error sphere, Represents the coordinates of the center of the intersecting section circle in the geocentric coordinate system, is the parameter of the intersecting section circle in polar coordinates, is the polar axis, is the polar angle; is the position coordinate of the radar in the geocentric coordinate system, is the relative speed between the radar and the target in the observation coordinate system established with the radar as the center; For the maximum relative distance , the radial velocity search range of the target is: in, The maximum relative distance The radial velocity search lower limit is The maximum relative distance The upper limit of the radial velocity search is given below.

5. The method for measuring distance and velocity of space targets using a space-based radar optical composite method as claimed in claim 4, wherein: For the minimum relative distance , the target's tangential velocity search range is: in, The minimum relative distance The lower limit of the tangential velocity search is The minimum relative distance The upper limit of the tangential velocity search under is the relative speed between the radar and the target in the observation coordinate system established with the radar as the center; For the maximum relative distance , the target's tangential velocity search range is: in, The maximum relative distance The lower limit of the tangential velocity search is The maximum relative distance The upper limit of the tangential velocity search is given below.

6. The method for measuring distance and velocity of space targets using a space-based radar optical composite method as claimed in claim 5, wherein: For the minimum relative distance , the radial acceleration search range of the target is: in, The minimum relative distance The search lower limit of radial acceleration under The minimum relative distance The search upper limit of radial acceleration under is the current relative distance between the radar and the target; For the maximum relative distance , the radial acceleration search range of the target is: in, The maximum relative distance The search lower limit of radial acceleration under The maximum relative distance The search upper limit for the radial acceleration under .

7. The method for measuring distance and velocity of space targets using a space-based radar optical composite method as claimed in claim 2, wherein: Target radial acceleration at different relative distances The expression is: in, is the current relative speed between the radar and the target in the observation coordinate system established with the radar as the center, is the current radial velocity of the target in the observation coordinate system established with the radar as the center, is the current relative distance between the radar and the target.

8. The method for measuring distance and velocity of space targets using a space-based radar optical composite method as claimed in claim 2, wherein: Target acceleration at different relative distances The expression is: in, is the current relative speed The relative acceleration between the radar and the target under is the current relative distance The target radial acceleration under is the current relative speed between the radar and the target in the observation coordinate system established with the radar as the center, is the current relative distance between the radar and the target.

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