High-dynamic weak space target space-based radar real-time measurement method and device

Abstract

The invention provides a high-dynamic weak space target space-based radar real-time measurement method and device, and belongs to the technical field of radar measurement. According to the method, maximum likelihood estimation is carried out by using search parameters to obtain target parameters. Selecting search values of radial relative acceleration and jerk in the search parameters, and determining upper and lower limits of a radial relative speed value according to a circular section where a radar search ball and a target position error ball intersect; according to the constraint relation of the radial relative speed to the radial relative acceleration, converting the upper limit and the lower limit of the value of the radial relative speed into a radial relative acceleration range, and selecting a radial relative acceleration search value from the radial relative acceleration range; the search values of the relative distance, the radial relative speed and the radial relative acceleration are utilized, and the search value of the radial relative jerk is uniquely determined through calculation. Compared with a traditional method, the method has the advantages that the parameter search dimension is reduced, the operand can be remarkably reduced, and the method can be implemented on a space-based platform in real time.

Description

Technical Field

[0001] The present invention relates to the technical field of radar measurement, and in particular to a real-time precise measurement method and device for high-dynamic weak space targets by a space-based radar. Background Art

[0002] With the rapid development of space activities, radar measurement of space targets, as a data source for space situation awareness, has gradually received extensive attention. Traditional ground-based radars are limited by the viewing angle, weather, and the curvature of the earth, and it is difficult to simultaneously meet the requirements for all-weather, large-range, and high-precision monitoring of space targets. In this context, space-based space target measurement radars rely on space-based platforms and can break through the limitations of ground-based radar observations to provide all-time and high-precision real-time measurement data of space targets.

[0003] However, under the strong constraints of resources such as layout space, weight, power consumption, and computing power on the space-based platform, there are many challenges in achieving high-precision measurement of large field-of-view and high-dynamic targets: Challenge 1, under the condition that the power aperture of the space-based radar is limited, the power of the radar echo signal of a long-distance target is weak and the signal-to-noise ratio is low, and long-time coherent integration is required to detect the target; Challenge 2, although the prior information of the target star position can be obtained through the SDP / SGP (Simplified Deep-space Perturbations / Simplified Deep-space Perturbations) orbit model based on TLE (Two Line Element), this method simplifies the earth's gravitational field and atmospheric model, and there is a large error between the predicted target star position and the actual position, and this error will gradually accumulate during a large amount of calculations and long-time simulations.

[0004] Therefore, after the orbital parameter prediction by the ground observation station, the traditional space target measurement method based on maximum likelihood estimation still needs to perform multi-dimensional parameter searches such as distance, speed, and acceleration, with high computational complexity. Typical methods include Radon-FrFT, Radon-LVD, Radon-Fourier Transform, Radon linear canonical transform, etc. For example, the GRFT algorithm proposed in the paper "Radon-Fourier transform for radar target detection (I): Generalized Doppler Filter Bank" published by Xu Jia in IEEE Transactions on Aerospace and Electronic Systems in 2011 projects the received echo signal into the parameter space composed of the three to form a "multi-dimensional focused image" of the target when dealing with uniformly accelerating moving targets, and then jointly compensates for the range migration and Doppler spread of the target envelope to obtain accurate target parameter values. At the same time, for high-dynamic moving targets such as approaching targets in different orbital planes, the GRFT algorithm can also expand the jerk dimension on the basis of the traditional three-dimensional parameter search of distance, speed, and acceleration to perform four-dimensional parameter search to match the more complex application scenarios of target motion.

[0005] In summary, in order to perform real-time precise measurement of the range and speed parameters of high-dynamic space targets, the traditional maximum likelihood estimation algorithm needs to perform parameter searches from multiple dimensions such as distance, speed, acceleration, and jerk. However, while improving the parameter estimation performance, the computational complexity of this algorithm has increased significantly. Considering the computing power constraints of the space-based radar system, it is difficult to implement this algorithm in real time on the space-based platform.

[0006] Therefore, on the basis of comprehensively considering factors such as the computational complexity and computational overhead of the algorithm, it is of great significance to study a low-complexity and high-precision parameter estimation algorithm adapted to the computing power of the space-based radar. Summary of the Invention

[0007] In view of this, the present invention provides a real-time precise measurement method and device for high-dynamic weak space targets by a space-based radar, which can achieve real-time precise measurement with low computing power.

[0008] To solve the above technical problems, the present invention is implemented as follows.

[0009] A real-time measurement method for high-dynamic weak space targets by a space-based radar, including: According to the orbital parameters of our star and the target star, determine the prior information including the relative distance between the two stars and the position of the target star; Select search parameters; among them, when selecting the search value of the radial relative acceleration and the search value of the radial relative jerk , according to the relative distance , the selected relative distance search value and the positions of our star and the target star, determine the radar search sphere and the target position error sphere; determine the upper and lower limits of the radial relative velocity within the circular cross-section formed by the intersection of the radar search sphere and the target position error sphere; according to the constraint relationship between the radial relative velocity and the radial relative acceleration, convert the upper and lower limits of the radial relative velocity into the corresponding radial relative acceleration range, and select the radial relative acceleration search value from the radial relative acceleration range; use the calculation relationship between the relative distance, the radial relative velocity, the radial relative acceleration and the radial relative jerk to calculate the radial relative jerk search value in the current search parameters ; Use the search parameters to perform maximum likelihood estimation to obtain the target parameters.

[0010] Preferably, in the step of selecting search parameters, when selecting the relative distance search value , according to the relative distance between the two stars and the distance error , determine the relative distance search range; select the relative distance search value from the relative distance search range.

[0011] Preferably, in the step of selecting search parameters, when selecting the relative radial velocity search value , select the relative radial velocity search value from the set relative radial velocity search range.

[0012] Preferably, the determination of the upper and lower limits of the radial relative velocity within the circular cross-section formed by the intersection of the radar search sphere and the target position error sphere is as follows: The coordinates of the center of the circular cross-section formed by the intersection of the radar search sphere and the target position error sphere are ; Determine two orthogonal unit vectors and in the circular cross-section; Calculate the variable ; in the formula is the radius of the circular cross-section, is the position coordinate of our star in the geocentric coordinate system, is the prior value of the relative velocity determined from the orbital parameters; The lower limit of the calculated radial relative velocity value is: Determine whether it satisfies , if so, the lower limit value of the radial relative velocity is ; otherwise, ; The upper limit of the calculated radial relative velocity value is: Determine whether it satisfies , if so, the upper limit value of the radial relative velocity is ; otherwise is .

[0013] Preferably, according to the constraint relationship between the radial relative velocity and the radial relative acceleration, converting the upper and lower limits of the radial relative velocity value into the corresponding radial relative acceleration range is: Based on the prior value of the relative velocity determined by the orbital parameters and the upper and lower limits of the radial relative velocity value, calculate the upper limit and the lower limit of the tangential relative velocity:

[0014] In the formula and are respectively the upper limit of the radial relative velocity value and the lower limit of the radial relative velocity value determined within the circular cross-section formed by the intersection of the radar search sphere and the target position error sphere; According to the relationship between the radial relative acceleration and the tangential relative velocity, determine the radial relative acceleration range as:

[0015] In the formula is the relative distance search value in this set of search parameters; Sample multiple acceleration search values from the radial relative acceleration range , corresponding to the same relative distance search value .

[0016] Preferably, using the calculation relationship between the relative distance, the radial relative velocity, the radial relative acceleration and the radial relative jerk, calculate the radial relative jerk search value in the current search parameters as: Calculate the radial relative jerk search value using the following formula:

[0017] In the formula, is the prior value of the relative velocity determined by the orbital parameters, For the relative velocity prior value The relative acceleration of our satellite and the target satellite obtained by modulus differential.

[0018] The present invention also discloses a space-based radar real-time measurement device for high-dynamic weak space targets, and the device includes: An orbital parameter acquisition and calculation module, configured to determine prior information including the relative distance between the two satellites and the position of the target satellite according to the orbital parameters of our satellite and the target satellite; A distance search value determination module, configured to determine a relative distance search value ; A velocity search value determination module, configured to determine a radial relative velocity search value ; An acceleration search value determination module, configured to determine a radar search sphere and a target position error sphere according to the relative distance , the selected relative distance search value , the positions of our satellite and the target satellite; determine the upper and lower limits of the radial relative velocity value within the circular cross-section formed by the intersection of the radar search sphere and the target position error sphere; according to the constraint relationship between the radial relative velocity and the radial relative acceleration, convert the upper and lower limits of the radial relative velocity value into corresponding radial relative acceleration ranges, and select a radial relative acceleration search value from the radial relative acceleration ranges ; A jerk search value determination module, configured to calculate a radial relative jerk search value in the current search parameters by using the calculation relationship between the relative distance, the radial relative velocity, the radial relative acceleration, and the radial relative jerk ; A maximum likelihood estimation module, which performs maximum likelihood estimation by using the determined search parameters to obtain target parameters.

[0019] Preferably, the distance search value determination module determines the relative distance search value in the following manner: according to the relative distance between the two satellites and the distance error , determine the relative distance search range; select a relative distance search value from the relative distance search range ; The velocity search value determination module determines the radial relative velocity search value in the following manner: select a relative radial velocity search value from the set relative radial velocity search range .

[0020] Preferably, the acceleration search value determination module includes a radial relative velocity upper and lower limit calculation unit and a radial relative acceleration range calculation unit; The radial relative velocity upper and lower limit conversion unit determines a radar search sphere and a target position error sphere according to the relative distance , the selected relative distance search value , the positions of the satellite of our side and the target satellite; the center coordinates of the circular cross-section formed by the intersection of the radar search sphere and the target position error sphere are ; determine two orthogonal unit vectors and in the circular cross-section; calculate the variable ; in the formula is the radius of the circular cross-section, is the position coordinate of the satellite of our side in the geocentric coordinate system, is the prior value of the relative velocity determined from the orbital parameters; Judge whether it satisfies , if so, the lower limit value of the radial relative velocity is ; otherwise ; judge whether it satisfies , if so, the upper limit value of the radial relative velocity is ; otherwise is ; The radial relative acceleration range calculation unit is used to calculate the upper limit and the lower limit of the tangential relative velocity based on the prior value of the relative velocity and the upper and lower limits of the radial relative velocity value:

[0021] In the formula and are respectively the upper limit and the lower limit of the radial relative velocity value determined within the circular cross-section formed by the intersection of the radar search sphere and the target position error sphere; Determine the radial relative acceleration range as:

[0022] In the formula is the relative distance search value in this set of search parameters; Sample multiple acceleration search values from the radial relative acceleration range , corresponding to the same relative distance search value .

[0023] Preferably, the jerk search value determination module calculates the radial relative jerk search value using the following formula :

[0024] In the formula, is the prior value of the relative velocity determined from the orbital parameters, is the relative acceleration of our satellite and the target satellite obtained by differentiating the modulus value of the prior value of the relative velocity .

[0025] Beneficial effects: Compared with the traditional maximum likelihood estimation algorithm, which is a precise ranging and velocity measurement method based on the search of four-dimensional parameters of distance, velocity, acceleration, and jerk, the present invention takes into account various constraint conditions of the space-based platform and designs a real-time precise measurement method for high-dynamic weak space targets with strong computing power constraints and low computing power.

[0026] This scheme first proves that in the measurement coordinate system, there is a quantitative mapping relationship between the target relative acceleration, relative distance, and relative velocity, and the jerk can be approximately determined by the relative distance and acceleration.

[0027] Based on the above proof results, in the parameter search process of the present invention, for the acceleration dimension, the acceleration distribution at different search distances is calculated in real time through the derived relationship, thereby reducing the search range, rather than directly using the given acceleration search range; for the jerk dimension, the present invention directly obtains it according to the calculation formula without parameter search. It can be seen that the present invention reduces the parameter search dimension by reducing the search range of the acceleration dimension and replacing the search with the calculation of the jerk dimension, significantly reducing the computational complexity and being able to be realized in real time on the space-based platform. Description of the drawings

[0028] Figure 1 is a schematic diagram of the relative measurement coordinate system.

[0029] Figure 2 is a schematic diagram of radar search and error sphere in space.

[0030] Figure 3 is a flowchart of the real-time measurement method for high-dynamic weak space targets by the space-based radar in the embodiment of the present invention.

[0031] Figure 4 is a schematic diagram of the real-time measurement device for high-dynamic weak space targets by the space-based radar in the embodiment of the present invention.

[0032] Figure 5 is a schematic diagram of the acceleration search range before and after dimension reduction.

[0033] Figure 6To derive the schematic diagram of the jerk range. Specific implementation mode

[0034] The present invention will be described in detail below with reference to the accompanying drawings and by way of examples.

[0035] First, in the embodiment of the present invention, the target relative motion model is derived first to prove that there is a quantitative mapping relationship between the target relative acceleration, relative distance, and relative velocity; then the relationship that the jerk can be approximately determined by the relative distance and acceleration is determined. According to the above relationship, the dimensionality reduction of parameter search can be carried out, which can effectively reduce the amount of calculation.

[0036] The derivation process of the present invention includes the following aspects: (1) First, according to the orbital parameters of our satellite and the target satellite, the radial acceleration constraint relationship is determined.

[0037] A relative measurement coordinate system of the target satellite is established, as Figure 1 shown. Considering the motion state of two satellites approaching each other in space, an observation system is established with our satellite as the center. Let the relative distance between our satellite and the target satellite be , and the relative velocity be . Project onto the radial and tangential directions respectively to obtain the radial relative velocity (hereinafter simply referred to as the radial velocity ), and the tangential relative velocity (hereinafter simply referred to as the tangential velocity ), where the radial direction is from our satellite to the target satellite. Similarly, the relative acceleration can be decomposed into the radial relative acceleration (hereinafter simply referred to as the radial acceleration ) and the tangential relative acceleration (abbreviated as the tangential acceleration ). The relationship between the radial acceleration and the tangential velocity can be expressed as: (1) It can be seen from equation (1) that the radial acceleration can be uniquely determined by the tangential velocity and the relative distance . Since the tangential velocity and the radial velocity satisfy relationship, the search range of the radial acceleration at a certain search distance can be determined by solving the value range of the radial velocity.

[0038] (2) Determine the constraint relationship of the radial jerk On the basis of equation (1), differentiating the radial acceleration gives the radial jerk The expression is as follows: (2) Expanding the above formula, we can get (3) And there is (4) Substituting formula (4) into formula (3), we can get: (5) Also because (6) Then we can substitute equations (5) and (6) into equation (2) to obtain the radial acceleration: The expression is: (7) in Represents the relative speed between the target star and our star The differential of is the relative acceleration. The relative velocity prior value obtained based on orbital parameters is adopted.

[0039] (3) Analysis of acceleration With jerk The correspondence.

[0040] Assume there is acceleration According to formula (1), we know that at this point is also determined according to the following velocity vector relationship: (8) Also know Substituting equations (1) and (8) into equation (7) yields the radial jerk: expression: (9) Consider the first term in the above formula , it is not difficult to find that for the known velocity determined by the orbital parameters and determine the unknown relative acceleration , both of which are related to the relative distance Regardless, when the radius is The spherical surface of is intercepted by the target prior position error sphere. To set the relative distance error, Figure 2 As shown, each point corresponds to Therefore, according to formula (9), under each acceleration search value, only one jerk value needs to be searched, thus achieving search dimensionality reduction.

[0041] In practical applications, the orbital parameters of the target star can be obtained through ground measurements or other means, and then the relative distance between the two stars can be obtained. and the relative velocity of the prior information. However, due to the existence of orbital parameter errors, the prior information can only determine the approximate position of the target star. And the possible positions of the target star form a sphere of error with the possible position of the target star as the center and the distance error as the radius, which is called the target position error sphere. When our satellite measures the distance and velocity parameters of the target star through the space-based radar, a search radar search sphere can be obtained with the position of our satellite as the center and the relative distance search value as the radius. And because the distance search value is equally spaced within the relative distance search range, multiple radar search spheres are obtained, which are also called radar equidistant stepped projection spherical surfaces. The cross-section determined by the intersection of the radar search sphere and the target position error sphere is a circle. In order to reduce the computational complexity, it is necessary to calculate the dynamic range of the radial velocity changing with the distance in real time.

[0042] As Figure 2 shown, the position coordinates of our satellite in the geocentric coordinate system, the relative velocity , for the intersecting circle: the position coordinates of the center , the radius is , and the normal vector of the plane where it is located , then the possible target position may be any point on the circle . The problem of the value range of the radial velocity can be transformed into solving the maximum and minimum values of the modulus of the inner product (the projection of the relative velocity in the radial direction).

[0043] Using two orthogonal unit vectors and within the circular cross-section, any point Q on the circle can be parametrically represented in polar coordinates as: (10) In the formula, represents the center coordinates, are the polar radius and azimuth parameters in polar coordinates.

[0044] The radial velocity (the projection of the relative velocity in the direction ) can be expressed as: (11) In the formula , , . To ensure that the radial velocity reaches its maximum or minimum value, when calculating the values of A and B, the maximum value, i.e., the radius R of the circular cross-section, should be substituted.

[0045] Since , analyzing the above formula shows that: For the minimum value of the radial velocity, if , then the lower limit of the radial velocity is ; if , then the lower limit of the radial velocity is 0.

[0046] For the maximum value of the radial velocity, if , then the upper limit of the radial velocity is ; if , then the upper limit of the radial velocity is .

[0047] It should be noted that the selected upper and lower limits of the radial velocity here are only intermediate quantities for calculating the range of the radial acceleration and do not serve as the range for selecting the search value of the radial velocity.

[0048] Based on the above analysis in (1)-(4), the implementation process of the space-based radar real-time measurement method for high-dynamic weak space targets of the present invention will be described in detail below in combination with Figure 3 . As shown in Figure 3 , the method includes the following steps: Step 1: Obtain the orbital parameters of our satellite and the target satellite, and use the orbital parameters to determine the relative distance , the prior value of the relative velocity and the prior information of the target satellite's position.

[0049] Step 2: Select the relative distance search value .

[0050] In this embodiment, according to the relative distance between the two satellites and the distance error , determine the relative distance search range ; select the relative distance search value from this relative distance search range.

[0051] Step 3: Select the relative radial velocity search value .

[0052] In this embodiment, set the relative radial velocity search range . The search methods for the relative distance and radial velocity in Steps 2 and 3 are the same as those in the prior art. Therefore, the number of searches for the relative distance and radial velocity in Table 2 of the following examples is the same as that of the traditional maximum likelihood algorithm.

[0053] Step 4: Select the relative radial acceleration search value .

[0054] In this step, according to the relative distance , the selected relative distance search value and the positions of our satellite and the target satellite, determine the radar search sphere and the target position error sphere; determine the upper and lower limits of the radial velocity value within the circular cross-section formed by the intersection of the radar search sphere and the target position error sphere; according to the constraint relationship between the radial velocity and the radial acceleration, convert the upper and lower limits of the radial velocity value into the corresponding radial acceleration range, and select the radial acceleration search value from the radial acceleration range .

[0055] The specific implementation process of this Step 4 includes the following sub-steps: Step 41: Determine the radar equidistant stepped projection spherical surface with the coordinates of our satellite as the center and the relative distance search value as the radius; determine the radar search sphere with the coordinates of the target satellite determined based on the orbital parameters as the center and the distance error as the radius; the radar equidistant stepped projection spherical surface and the radar search sphere intersect to form a circular cross-section. The center coordinates of the circular cross-section are .

[0056] Step 42: Determine two orthogonal unit vectors and in the circular cross-section.

[0057] One way to obtain the orthogonal unit vectors and is as follows: The orthogonal unit vector is obtained by cross-multiplying the normal vector by the unit vector, and then is cross-multiplied by to obtain .

[0058] Step 43: Calculate the variable ; in the formula, to ensure that the radial velocity reaches the maximum and minimum values, substitute the maximum value, that is, the radius of the circular cross-section, and substitute the prior value of the relative velocity determined from the orbital parameters.

[0059] Step 44: Calculate the upper and lower limits of the radial velocity value.

[0060] For the lower limit of the radial velocity value: Determine whether it satisfies . If so, the lower limit value of the radial velocity is ; otherwise, the lower limit value of the radial velocity .

[0061] For the upper limit of the radial velocity value: Determine whether it satisfies . If so, the upper limit value of the radial velocity is ; otherwise, the upper limit value of the radial velocity is .

[0062] The upper and lower limits and obtained in this step are only used for calculating the radial acceleration range in step 45 and are not used as the relative radial velocity search range adopted in step 3.

[0063] Step 45: Use the constraint relationship between the radial velocity and the radial acceleration to convert the upper and lower limits of the radial velocity value into the corresponding radial acceleration range .

[0064] In this step, due to the constraint relationship between the tangential velocity and the radial velocity, when the radial velocity reaches the maximum, the tangential velocity reaches the minimum, and when the radial velocity reaches the minimum, the tangential velocity reaches the maximum, that is: (12) In the above formula, the prior value of the relative velocity determined by the orbital parameters is adopted. and the upper and lower limits of the radial velocity value calculated in step 44 are adopted.

[0065] According to the constraint relationship of formula (1), and taking the r relative distance search value in the formula, the maximum value and the minimum value of the radial acceleration search range can be obtained: (13) It can be seen from this that when searching for the target with a relative distance of , the radial acceleration search range is .

[0066] Sample multiple radial acceleration search values from the radial acceleration range , corresponding to the same relative distance search value . When the sampling step size is the same, the longer, the radial acceleration search value The more the quantity selected, if is a value, then the radial acceleration search value is only one. Therefore, in Table 2 of the following examples, the acceleration search times are 1 - 336, which is a variable quantity.

[0067] Step 5: Select the radial jerk search value .

[0068] In this step, using the calculation relationships between the relative distance, radial velocity, radial acceleration and radial jerk, calculate the radial jerk search value in the current search parameters .

[0069] Specifically, as can be seen from Equation (9) above, the radial jerk can be uniquely determined by the relative distance , radial velocity and radial acceleration . Therefore, when the relative distance search value , radial velocity search value and radial acceleration search value have been determined in Steps 2 - 4, the radial jerk search value can be directly calculated by Equation (9) without searching within the range given by the jerk, thus reducing the parameter search dimension.

[0070] Specifically, the following formula is used to calculate the radial jerk search value :

[0071] In the formula, adopts the prior value of the relative velocity determined by the orbital parameters, uses the prior value of the velocity to obtain the modulus differential, which is the relative acceleration between our satellite and the target satellite.

[0072] Step 6: Use the search parameters to perform maximum likelihood estimation to obtain the target parameters that maximize the coherent accumulation of the echo signal.

[0073] After the selection in Steps 2 - 5, a series of search parameters are determined. In this step, maximum likelihood estimation is performed according to the search parameters. The principle of the maximum likelihood estimation algorithm is as follows: Assume that the transmitted signal in the n th period is , where is the slow time, is the pulse period, is the fast time, and the target echo signal can be modeled as: (14) In the formula represents the echo signal amplitude (including the target reflection characteristics), τ represents the time delay (related to the target distance R), represents noise (usually assumed to be additive white Gaussian noise).

[0074] Performing coherent integration on the echo signal, the result of coherent integration is used as the likelihood function, which can be expressed as: (15) In the formula , is the speed of light, N is the number of coherent integrations, is the phase compensation function for realizing pulse coherent integration. respectively represent the relative distance, radial velocity, radial acceleration, and radial jerk. This formula (15) is a general formula. For simplicity, the parameters do not have subscripts added.

[0075] The maximum value of can be found according to the likelihood function, and the parameter estimation value is expressed as follows: (16) In the formula are the estimation results of the relative distance, radial velocity, radial acceleration, and radial jerk.

[0076] The maximum likelihood estimation only provides a theoretical framework for parameter estimation through model matching. Taking the GRFT (Generalized Radon - Fourier Transform) algorithm as an example, a method for measuring the distance and velocity of high - dynamic space targets is introduced. According to the GRFT algorithm, the third - order GRFT expression can be obtained as: (17) where is the result after GRFT coherent integration of the echo signal, , are the search parameters determined in the above steps, . is the wavelength.

[0077] The discrete expression of formula (17) is: (18) where is the discrete search sequence number of is the echo signal after pulse compression, , is the sampling frequency, is the rounding function.

[0078] It can be seen from Equation (18) that when the search distance in the discrete domain , radial velocity , radial acceleration , and jerk are respectively equal to the true relative distance of the target , radial velocity , radial acceleration , and jerk , the energy of each echo pulse within the coherent integration time can be aggregated, thereby achieving coherent integration and finally obtaining the target parameters, which are mainly range and velocity.

[0079] In the parameter search process of the present invention, for the acceleration dimension, the acceleration distribution at different search distances can be calculated in real time according to the conclusions derived from Formulas (11) to (13), thereby reducing the search range; for the jerk, it can be directly obtained according to Formula (9) without parameter search. It can be seen that the present invention reduces the parameter search dimension compared with the traditional method, can significantly reduce the computational amount, and can be realized in real time on the space-based platform.

[0080] Based on the above method, the present invention further provides a space-based radar real-time measurement device for high-dynamic weak space targets, as Figure 4 shown. The device includes: an orbital parameter acquisition and calculation module, a range search value determination module, a velocity search value determination module, an acceleration search value determination module, a jerk search value determination module, and a maximum likelihood estimation module. Among them, The orbital parameter acquisition and calculation module is used to determine the relative distance , relative velocity between the two satellites and the prior information of the target satellite's position according to the orbital parameters of our satellite and the target satellite.

[0081] The range search value determination module is used to determine the relative range search value .

[0082] The velocity search value determination module is used to determine the radial velocity search value .

[0083] The acceleration search value determination module is used to determine the acceleration search value according to the relative distance , the selected relative range search value , determine the radar search sphere and the target position error sphere based on the positions of our satellite and the target satellite; determine the upper and lower limits of the radial velocity within the circular cross-section formed by the intersection of the radar search sphere and the target position error sphere; according to the constraint relationship between the radial velocity and the radial acceleration, convert the upper and lower limits of the radial velocity into the corresponding radial acceleration range, and select the radial acceleration search value from the radial acceleration range 。

[0084] The jerk search value determination module is used to calculate the jerk search value in the current search parameters by using the calculation relationship between the relative distance, radial velocity, radial acceleration, and jerk 。

[0085] The maximum likelihood estimation module uses the determined search parameters to perform maximum likelihood estimation to obtain the target parameters that maximize the coherent accumulation of the echo signal

[0086] Among them, the distance search value determination module determines the relative distance search value in the following way: determine the relative distance search range according to the relative distance between the two satellites and the distance error ; select the relative distance search value from the relative distance search range 。

[0087] The velocity search value determination module determines the radial velocity search value in the following way: select the relative radial velocity search value from the set relative radial velocity search range 。

[0088] In a preferred embodiment, the acceleration search value determination module includes a radial velocity upper and lower limit calculation unit and a radial acceleration range calculation unit

[0089] The radial velocity upper and lower limit conversion unit determines the radar search sphere and the target position error sphere according to the relative distance , the selected relative distance search value , and the positions of our satellite and the target satellite. The center coordinates of the circular cross-section formed by the intersection of the radar search sphere and the target position error sphere are ; determine the two orthogonal unit vectors and in the circular cross-section; calculate the variable ; where is the radius of the circular cross-section, is the position coordinate of our satellite in the geocentric coordinate system, is the prior value of the relative velocity determined from the orbital parameters

[0090] Judge whether it satisfies , if so, the lower limit value of the radial velocity is ; otherwise, ; determine whether it satisfies , if so, the upper limit value of the radial velocity is ; otherwise is ; Radial acceleration range calculation unit, for calculating the upper limit of the tangential relative velocity and the lower limit of the tangential relative velocity based on the prior value of the relative velocity determined by the orbital parameters :

[0091] In the formula and are respectively the upper limit and the lower limit of the radial velocity value determined within the circular cross-section formed by the intersection of the radar search sphere and the target position error sphere; According to the relationship between the radial acceleration and the tangential relative velocity, determine the radial acceleration range as:

[0092] In the formula is the relative distance search value in this set of search parameters; Sample multiple acceleration search values from the radial acceleration range , corresponding to the same relative distance search value .

[0093] In a preferred embodiment, the jerk search value determination module calculates the radial jerk search value using the following formula :

[0094] In the formula, is the prior value of the relative velocity determined by the orbital parameters, is the relative acceleration between the satellite of our side and the target satellite obtained by differentiating the modulus value of the prior value of the relative velocity .

[0095] Next, a specific example is given to describe the solution and effect of the present invention in detail.

[0096] In this embodiment, the satellite of our side approaches the target satellite with orbital inclination, and measures the relative distance and velocity parameters of the two satellites. The specific simulation parameters are as shown in Table 1 below: Table 1

[0097] First, through the guidance of orbital parameters, the prior information of the relative distance between the two stars is obtained as 50 km, and the distance error is 5 km. Then the possible positions of the target star form a target position error sphere in space with a center distance of 50 km from our star and a radius of 5 km.

[0098] Using the present invention, by calculating in real time the cross-sectional geometric parameters of the radar equidistant stepped projection spherical surface and the target position error sphere, the dynamic error range of the acceleration varying with the distance is obtained, and through the derived jerk constraint relationship, the jerk can be obtained without searching. The comparison of the search ranges of the acceleration parameters before and after dimensionality reduction is as Figure 5 shown. The search range of the traditional GRFT algorithm is the area enclosed by the dashed line; the search range after dimensionality reduction by the present invention is the area enclosed by the solid line in the figure. The value ranges of the jerk parameters obtained before and after dimensionality reduction are as Figure 6 shown.

[0099] Using the parameters shown in Table 1 above, the operation amounts of the traditional maximum likelihood estimation algorithm and the dimensionality reduction search algorithm are calculated respectively (the operation amount is measured by the number of real number multiplications), and the results shown in Table 2 below are obtained.

[0100] Table 2

[0101] From the comparison chart of the acceleration and jerk search ranges in the simulation and the fact that the total operation amount in Table 2 above is reduced by 92 times, it is concluded that the dimensionality reduction GRFT parameter search method proposed by the present invention can significantly reduce the operation amount and can realize high-precision distance and speed parameter measurement in real time on a space-based platform with limited computing power.

[0102] The above specific embodiments only describe the design principle of the present invention. The shapes and names of the components in this description can be different and are not limited. Therefore, those skilled in the art of the present invention can modify or equivalently replace the technical solutions recorded in the foregoing embodiments; and these modifications and replacements do not depart from the gist and technical solutions of the present invention, and shall all fall within the protection scope of the present invention.

Claims

1. A high-dynamic weak space target space-based radar real-time measurement method, characterized in that: include: According to the orbital parameters of our satellite and the target satellite, determine the relative distance between the two satellites and prior information of the target star’s position; Select the search parameters; among them, select the radial relative acceleration search value and radial relative jerk search value When, according to the relative distance , the selected relative distance search value As well as the positions of our satellite and the target satellite, determine the radar search sphere and the target position error sphere; determine the upper and lower limits of the radial relative velocity value in the circular cross-section formed by the intersection of the radar search sphere and the target position error sphere; according to the constraint relationship between the radial relative velocity and the radial relative acceleration, convert the upper and lower limits of the radial relative velocity value into the corresponding radial relative acceleration range, and select the radial relative acceleration search value from the radial relative acceleration range. ; Using the calculation relationship between relative distance, radial relative velocity, radial relative acceleration and radial relative jerk, calculate the radial relative jerk search value in the current search parameter ; The search parameters are used to perform maximum likelihood estimation to obtain the target parameters.

2. The high-dynamic weak space target space-based radar real-time measurement method according to claim 1, characterized in that: In the step of selecting search parameters, the relative distance search value in the selected search parameters When the relative distance between the two stars and distance error , determine a relative distance search range; select a relative distance search value from the relative distance search range .

3. The high-dynamic weak space target space-based radar real-time measurement method according to claim 1, characterized in that: In the step of selecting the search parameters, the relative radial velocity search value in the selected search parameters is When the relative radial velocity search value is selected from the set relative radial velocity search range .

4. The high-dynamic weak space target space-based radar real-time measurement method according to claim 1, characterized in that: The upper and lower limits of the radial relative velocity determined in the circular cross section formed by the intersection of the radar search sphere and the target position error sphere are: The coordinates of the center of the circular section formed by the intersection of the radar search sphere and the target position error sphere are: ; Determine the two orthogonal unit vectors in the circular cross section and ; Calculated variables ; In the formula is the radius of the circular cross section, is the position coordinate of our star in the geocentric system, is the prior value of relative velocity determined by orbital parameters; Calculate the lower limit of the radial relative velocity: Determine whether If yes, then the lower limit of radial relative speed is for ; otherwise, ; Calculate the upper limit of the radial relative velocity: Determine whether If yes, then the upper limit of radial relative speed is for ;otherwise for .

5. The high-dynamic weak space target space-based radar real-time measurement method according to claim 1, characterized in that: According to the constraint relationship between the radial relative velocity and the radial relative acceleration, the upper and lower limits of the radial relative velocity are converted into the corresponding radial relative acceleration range: Based on the relative velocity prior value determined by the orbital parameters and the upper and lower limits of the radial relative velocity, calculate the upper limit of the tangential relative velocity and lower limit : In the formula and are respectively the upper limit and the lower limit of the radial relative velocity determined in the circular cross section formed by the intersection of the radar search sphere and the target position error sphere; According to the relationship between radial relative acceleration and tangential relative velocity, the radial relative acceleration range is determined. for: In the formula The relative distance search value in this set of search parameters; From the radial relative acceleration range Sampling multiple acceleration search values , corresponding to the same relative distance search value .

6. The high-dynamic weak space target space-based radar real-time measurement method according to claim 1, characterized in that: The radial relative acceleration search value in the current search parameter is calculated by using the calculation relationship between the relative distance, the radial relative speed, the radial relative acceleration and the radial relative jerk. for: The radial relative acceleration search value is calculated using the following formula: : In the formula, is the relative velocity prior value determined by the orbital parameters, The relative speed prior value is used The relative acceleration between our star and the target star is obtained by differential modulus.

7. A high-dynamic weak space target space-based radar real-time measurement device, characterized in that: The device includes: The orbital parameter acquisition and calculation module is used to determine the relative distance between the two stars based on the orbital parameters of the satellite and the target star. and prior information of the target star’s position; A distance search value determination module is used to determine a relative distance search value. ; A speed search value determination module is used to determine the radial relative speed search value. ; The acceleration search value determination module is used to determine the acceleration value according to the relative distance , the selected relative distance search value As well as the positions of our satellite and the target satellite, determine the radar search sphere and the target position error sphere; determine the upper and lower limits of the radial relative velocity value in the circular cross-section formed by the intersection of the radar search sphere and the target position error sphere; according to the constraint relationship between the radial relative velocity and the radial relative acceleration, convert the upper and lower limits of the radial relative velocity value into the corresponding radial relative acceleration range, and select the radial relative acceleration search value from the radial relative acceleration range. ; The jerk search value determination module is used to calculate the radial relative jerk search value in the current search parameter by using the calculation relationship between the relative distance, the radial relative velocity and the radial relative acceleration and the radial relative jerk. ; The maximum likelihood estimation module uses the determined search parameters Perform maximum likelihood estimation to obtain the target parameters.

8. The high-dynamic weak space target space-based radar real-time measurement device according to claim 7, characterized in that: The distance search value determination module determines a relative distance search value The method is: according to the relative distance between the two stars and distance error , determine a relative distance search range; select a relative distance search value from the relative distance search range ; The speed search value determination module determines a radial relative speed search value The method is: select the relative radial velocity search value from the set relative radial velocity search range .

9. The high-dynamic weak space target space-based radar real-time measurement device according to claim 7, characterized in that: The acceleration search value determination module includes a radial relative speed upper and lower limit calculation unit and a radial relative acceleration range calculation unit; The radial relative speed upper and lower limit conversion unit is configured to convert the relative distance , the selected relative distance search value As well as the positions of our satellite and target satellite, determine the radar search sphere and target position error sphere; The coordinates of the center of the circular section formed by the intersection of the radar search sphere and the target position error sphere are: ; Determine the two orthogonal unit vectors in the circular cross section and ; Calculated variables ; In the formula is the radius of the circular cross section, is the position coordinate of our star in the geocentric system, is the prior value of relative velocity determined by orbital parameters; Determine whether it is satisfied If yes, then the lower limit of radial relative speed is for ; otherwise, ; Determine whether If yes, then the upper limit of radial relative speed is for ; otherwise for ; The radial relative acceleration range calculation unit is used to calculate the relative speed based on the relative speed prior value. and the upper and lower limits of the radial relative velocity, calculate the upper limit of the tangential relative velocity and lower limit : In the formula and are respectively the upper limit and the lower limit of the radial relative velocity determined in the circular cross section formed by the intersection of the radar search sphere and the target position error sphere; According to the relationship between radial relative acceleration and tangential relative velocity, the radial relative acceleration range is determined. for: In the formula The relative distance search value in this set of search parameters; From the radial relative acceleration range Sampling multiple acceleration search values , corresponding to the same relative distance search value .

10. The high-dynamic weak space target space-based radar real-time measurement device according to claim 7, characterized in that: The acceleration search value determination module calculates the radial relative acceleration search value using the following formula: : In the formula, is the relative velocity prior value determined by the orbital parameters, The relative speed prior value is used The relative acceleration between our star and the target star is obtained by differential modulus.

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