Method for high-precision real-time calculation of position information of dynamic cooperative target by satellite

Abstract

The invention relates to a method for high-precision real-time calculation of dynamic cooperative target position information by a satellite, and belongs to the field of satellite control systems. Performing normalization processing on moments corresponding to the discrete point position information of the dynamic cooperative target; obtaining a target planning attitude tracking curve L; respectively calculating the position information f (t0) of the dynamic cooperative target at the t0 moment and the position information f (t-5) of the dynamic cooperative target at the t0-5s moment; maneuvering the satellite to be aligned with the dynamic cooperative target position information f (t-5) at the t0-5s moment; the position f (ti) of the dynamic cooperative target after the satellite maneuvers in place is calculated, the satellite aligns to the position, and fine alignment of the satellite to the dynamic cooperative target is achieved; according to the method, the fitting success rate and precision are improved by selecting the proper fitting curve primary function and normalizing the corresponding moments of the discrete target positions; through forward extension of a fitting curve, a proper target position is gazed in advance, and the requirement of a satellite for high-precision real-time calculation of a dynamic cooperative target position is met.

Description

Technical Field

[0001] The invention belongs to the field of satellite control systems and relates to a method for satellites to calculate dynamic cooperative target position information in real time with high precision. Background Art

[0002] When the satellite guides and tracks a dynamic cooperative target, the motion parameters of the cooperative target, such as its position information, can be estimated in advance. However, the estimated result is a discrete point sequence with a large amount of data. If the discrete point information is directly uploaded to the satellite, the amount of uploaded data and the time required for uploading will be relatively large, making engineering implementation difficult. In addition, the discrete point sequence is usually equally spaced, but since the target motion speed shows great differences in different stages, some stages are relatively slow and some stages are relatively fast, the speed information calculated based on the differential position information of the equally spaced discrete points will be seriously distorted, affecting the stability of satellite tracking. Therefore, it is necessary to fit the discrete point sequence data of the dynamic cooperative target, and then upload the fitting coefficients to the satellite, which can not only reduce the amount of uploaded data, but also improve the accuracy and stability of guidance and tracking.

[0003] The curve fitting of discrete points usually adopts the least squares method, and the functions used are mainly polynomials and Fourier series. When the order is n, the Fourier series has a total of (n+1)*2 fitting coefficients, while the polynomial has (n+1) fitting coefficients. From the theoretical analysis and simulation results, it can be seen that the curve error of the 2*n order polynomial fitting is close to that of the n order Fourier series fitting. Due to the complex motion characteristics of dynamic cooperative targets, the use of Fourier series fitting generally requires more than 5 orders, and the corresponding polynomial fitting requires more than 10 orders. The Fourier series is in the form of trigonometric functions, and the polynomial is in the form of power. For onboard software, the calculation time of trigonometric functions is significantly greater than the calculation time of power. Therefore, from the perspective of saving the running time of onboard software, polynomial fitting is more suitable for engineering applications. However, when using a polynomial as a fitting function, even if the error of the time value as the independent variable is very small, the error will be sharply amplified after the 10th power operation, resulting in poor fitting accuracy. In addition, there is also an overflow risk for larger values, resulting in fitting failure.

[0004] On the other hand, when the satellite guides and tracks the cooperative target, it usually maneuvers from the current position to the specified position, then maintains a gaze state, and then performs guidance and tracking according to the fitting curve at the initial guidance moment. Switching directly from the gaze state to the guidance and tracking state will cause obvious attitude jitter, and the tracking error will be relatively large during the initial period of guidance and tracking. Summary of the invention

[0005] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art and propose a method for satellite to calculate the dynamic cooperation target position information in real time with high precision, by selecting a suitable fitting curve basis function and normalizing the corresponding moments of the discrete target position, thereby improving the fitting success rate and precision; by extending the fitting curve forward to stare at the appropriate target position in advance, the demand for satellite to calculate the dynamic cooperation target position in real time with high precision is met.

[0006] The solution of the present invention is:

[0007] A method for satellite high-precision real-time calculation of dynamic cooperative target position information, comprising:

[0008] The discrete point sequence of the dynamic cooperation target is set as D1, D2, ..., D N ; Define the position information of the dynamic cooperation target in the WGS84 coordinate system as the dynamic cooperation target discrete point position information; perform normalization processing on the time corresponding to the dynamic cooperation target discrete point position information;

[0009] The least square method of overdetermined equations is used to curve fit the discrete point sequence of dynamic cooperative targets to obtain the target planning posture tracking curve L;

[0010] Set the time corresponding to the first position point D1 of the dynamic cooperation target as t0; calculate the position information f(t0) of the dynamic cooperation target at t0 and the position information f(t0-5s) of the dynamic cooperation target at t0-5s according to the target planning posture tracking curve L. -5 ); t0-5s is the time 5s before t0;

[0011] Maneuver the satellite to align with the dynamic cooperative target position information f(t -5 ); After the satellite moves to its destination, calculate the position of the dynamic cooperation target at this moment f(t i ), the satellite aims at the position and keeps staring at it, achieving precise alignment of the satellite with the dynamic cooperation target.

[0012] In the above-mentioned method for calculating the position information of dynamic cooperative targets in real time with high precision by a satellite, N is a positive integer greater than 13; the position information in the WGS84 coordinate system includes longitude λ, latitude γ, and altitude h.

[0013] In the above-mentioned method for calculating the position information of dynamic cooperative targets in real time with high precision by a satellite, the specific method of normalization processing is:

[0014] Set the time corresponding to the first position point D1 of the dynamic cooperation target as t0, and the last position point D N The corresponding time is t f ; Let D1 and D NThe corresponding time of any dynamic cooperation target position point between them is t i , the normalized dynamic cooperation target position information corresponds to the time That is, the time t of all discrete points after normalization i ′ is between [0,1].

[0015] In the above-mentioned method for calculating the position information of dynamic cooperative targets in real time with high precision by a satellite, the method for curve fitting the discrete point sequence of the dynamic cooperative targets is:

[0016] For any point in the discrete point sequence, t i ∈[t0,t f ]、t i ′∈[0,1], which conforms to the fitting equation:

[0017] f(t i )=Φ T (t i ′)P i=1,2,…N

[0018] In the formula, f(t i ) is t i The dynamic cooperation target discrete point position information corresponding to the moment (λ i γ i h i );

[0019] Φ(t) is the designed basis function, which is in polynomial form;

[0020] P is the fitting coefficient of the polynomial, which is the unknown quantity;

[0021] Satisfies the following linear equations:

[0022]

[0023] Where, F is the position information matrix;

[0024] The fitting coefficient P is estimated using the least squares method of overdetermined equations:

[0025] P=(Φ T Φ) -1 Φ T F

[0026] After the fitting coefficient P is obtained, the fitting equation is obtained. The target planning posture tracking curve L is obtained by curve fitting the dynamic cooperative target discrete point sequence through the fitting equation.

[0027] In the above-mentioned method for calculating the position information of dynamic cooperative targets in real time with high precision by a satellite, the formula of the basis function Φ(t) is:

[0028] Φ(t)=(1 tt 2 t 3 t 4 t 5 t 6 t 7 t 8 t 9 t 10 t 11 t 12 ) T .

[0029] In the above-mentioned method for calculating the position information of dynamic cooperative targets in real time with high precision by a satellite, the target position information f(t0) at time t0 is:

[0030]

[0031] f(t0)=Φ T (t0′)P.

[0032] In the above-mentioned method for calculating the position information of dynamic cooperative targets in real time with high precision by satellite, the target position information f(t -5 )for:

[0033]

[0034] f(t -5 )=Φ T (t -5 ′)P.

[0035] In the above method for calculating the position information of a dynamic cooperative target in real time with high precision by a satellite, when the time ti when the satellite maneuvers to the position is between time t0-5s and time t0, the position f(t i )for:

[0036]

[0037] In the above-mentioned method for calculating the position information of dynamic cooperative targets in real time with high precision by a satellite, the least square method performs curve fitting based on the principle of minimum overall variance, so the fitting curve has high distortion at both ends, that is, the fitting error is large; if the fitting curve is used to calculate the target position from t0-5s to t0, obvious jitter will occur after reaching t0, so the linear interpolation method is used to achieve smooth switching of the satellite from the staring state to the guidance and tracking state.

[0038] In the above method for calculating the position information of dynamic cooperative targets in real time with high precision by a satellite, when the satellite maneuvers to the right position, i Between time t0 and t f At the time between the moments, the position of the dynamic cooperation target f(ti ) is calculated according to the target planning posture tracking curve L:

[0039]

[0040] f(t i )=Φ T (t i ′)P.

[0041] The beneficial effects of the present invention compared with the prior art are:

[0042] (1) The present invention improves the fitting success rate and accuracy by normalizing the moments corresponding to the discrete point sequence;

[0043] (2) The present invention extends the fitting curve forward and tracks in advance, thereby avoiding the sudden change of the target posture when the gaze state is switched to the guidance tracking state, and meets the requirements of the satellite to track the dynamic cooperative target with high precision and high stability, and has engineering feasibility;

[0044] (3) The present invention improves the fitting success rate and accuracy by selecting a suitable fitting curve basis function and normalizing the corresponding moments of discrete target positions; by extending the fitting curve forward to gaze at the appropriate target position in advance, the satellite realizes the need for high-precision real-time calculation of the dynamic cooperative target position. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 A flow chart of calculating the dynamic cooperation target position information of the present invention;

[0046] Figure 2 This is a schematic diagram of curve fitting and advance tracking of the present invention. DETAILED DESCRIPTION

[0047] The present invention will be further described below in conjunction with the embodiments.

[0048] The present invention provides a method for satellite to calculate the position information of dynamic cooperative targets in real time with high precision. By selecting a suitable fitting curve basis function and normalizing the corresponding moments of discrete target positions, the fitting success rate and precision are improved. By extending the fitting curve forward to gaze at the appropriate target position in advance, the demand for satellite to calculate the position of dynamic cooperative targets in real time with high precision is met.

[0049] A method for satellites to calculate the position information of dynamic cooperative targets in real time with high precision, such as Figure 1 As shown, the specific steps include:

[0050] The discrete point sequence of the dynamic cooperation target is set as D1, D2, ..., D N; N is a positive integer greater than 13; define the location information of the dynamic cooperation target in the WGS84 coordinate system as the dynamic cooperation target discrete point location information; the location information in the WGS84 coordinate system includes longitude λ, latitude γ, and altitude h. The time corresponding to the dynamic cooperation target discrete point location information is normalized.

[0051] The specific method of normalization is:

[0052] Set the time corresponding to the first position point D1 of the dynamic cooperation target as t0, and the last position point D N The corresponding time is t f ; Let D1 and D N The corresponding time of any dynamic cooperation target position point between them is t i , the normalized dynamic cooperation target position information corresponds to the time That is, the time t of all discrete points after normalization i ′ is between [0,1].

[0053] The least square method of overdetermined equations is used to perform curve fitting on the discrete point sequence of dynamic cooperative targets, and the target planning posture tracking curve L is obtained.

[0054] The method for curve fitting of dynamic cooperation target discrete point sequence is:

[0055] For any point in the discrete point sequence, t i ∈[t0,t f ]、t i ′∈[0,1], which conforms to the fitting equation:

[0056] f(t i )=Φ T (t i ′)P i=1,2,…N

[0057] In the formula, f(t i ) is the dynamic cooperation target discrete point position information corresponding to time ti (λ i γ i h i ).

[0058] Φ(t) is the designed basis function in polynomial form.

[0059] P is the fitting coefficient of the polynomial and is the unknown quantity.

[0060] The formula of the basis function Φ(t) is:

[0061] Φ(t)=(1 tt 2 t 3 t 4 t5 t 6 t 7 t 8 t 9 t 10 t 11 t 12 ) T .

[0062] Satisfies the following linear equations:

[0063]

[0064] Where, F is the position information matrix;

[0065] The fitting coefficient P is estimated using the least squares method of overdetermined equations:

[0066] P=(Φ T Φ) -1 Φ T F

[0067] After the fitting coefficient P is obtained, the fitting equation is obtained. The target planning posture tracking curve L is obtained by curve fitting the dynamic cooperative target discrete point sequence through the fitting equation.

[0068] Set the time corresponding to the first position point D1 of the dynamic cooperation target as t0; calculate the position information f(t0) of the dynamic cooperation target at t0 and the position information f(t0-5s) of the dynamic cooperation target at t0-5s according to the target planning posture tracking curve L. -5 ); t0-5s is the time 5s before t0.

[0069] The target position information f(t0) at time t0 is:

[0070]

[0071] f(t0)=Φ T (t0′)P.

[0072] The target position information f(t -5 )for:

[0073]

[0074] f(t -5 )=Φ T (t -5 ′)P.

[0075] Maneuver the satellite to align with the dynamic cooperative target position information f(t -5 ); After the satellite moves to its destination, calculate the position of the dynamic cooperation target at this moment f(ti ), the satellite aims at the position and keeps staring at it, achieving precise alignment of the satellite with the dynamic cooperation target.

[0076] When the satellite maneuvers to its correct position, i When the dynamic cooperation target is between t0-5s and t0, the position f(t i )for:

[0077]

[0078] The least square method is based on the principle of minimum overall variance for curve fitting. Therefore, the fitting curve has high distortion at both ends, that is, the fitting error is large. If the fitting curve is used to calculate the target position from t0-5s to t0, obvious jitter will occur after reaching t0. Therefore, the linear interpolation method is used to achieve smooth switching of the satellite from the staring state to the guidance tracking state.

[0079] When the satellite maneuvers to its correct position, i Between time t0 and t f At the time between the moments, the position of the dynamic cooperation target f(t i ) is calculated according to the target planning posture tracking curve L:

[0080]

[0081] f(t i )=Φ T (t i ′)P.

[0082] The present invention improves the fitting success rate and accuracy by normalizing the moments corresponding to the discrete point sequence; the present invention avoids the sudden change of the target posture when the gaze state is switched to the guidance tracking by extending the fitting curve forward and tracking in advance, thereby meeting the demand of satellite tracking of dynamic cooperative targets with high precision and high stability, and has engineering feasibility.

[0083] The present invention improves the fitting success rate and accuracy by selecting a suitable fitting curve basis function and normalizing the corresponding moments of discrete target positions; and realizes the requirement of satellite high-precision real-time calculation of dynamic cooperative target positions by extending the fitting curve forward to gaze at the suitable target position in advance.

[0084] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for satellite high-precision real-time calculation of dynamic cooperative target position information, characterized in that: include: The discrete point sequence of the dynamic cooperation target is set as D1, D2, ..., D N ; Define the position information of the dynamic cooperation target in the WGS84 coordinate system as the discrete point position information of the dynamic cooperation target; Normalize the time corresponding to the position information of the discrete points of the dynamic cooperation target; The least square method of overdetermined equations is used to perform curve fitting on the discrete point sequence of dynamic cooperative targets to obtain the target planning posture tracking curve L. Set the time corresponding to the first position point D1 of the dynamic cooperation target as t0; calculate the position information f(t0) of the dynamic cooperation target at t0 and the position information f(t0-5s) of the dynamic cooperation target at t0-5s according to the target planning posture tracking curve L. -5 ); t0-5s is the time 5s before t0; Maneuver the satellite to align with the dynamic cooperative target position information f(t -5 ); After the satellite moves to its destination, calculate the position of the dynamic cooperation target at this moment f(t i ), the satellite aims at the position and keeps staring at it, achieving precise alignment of the satellite with the dynamic cooperation target.

2. The method for calculating the position information of dynamic cooperative targets by satellites with high precision and in real time according to claim 1, characterized in that: N is a positive integer greater than 13; the position information in the WGS84 coordinate system includes longitude λ, latitude γ, and altitude h.

3. The method for calculating the position information of dynamic cooperative targets by satellites with high precision and in real time according to claim 1, characterized in that: The specific method of normalization is: Set the time corresponding to the first position point D1 of the dynamic cooperation target as t0, and the last position point D N The corresponding time is t f ; Let D1 and D N The corresponding time of any dynamic cooperation target position point between them is t i , the normalized dynamic cooperation target position information corresponds to the time That is, the time t of all discrete points after normalization i ′ is between [0,1].

4. The method for calculating the position information of dynamic cooperative targets by satellites with high precision and in real time according to claim 3, characterized in that: The method for curve fitting of dynamic cooperation target discrete point sequence is: For any point in the discrete point sequence, t i ∈[t0,t f ]、t i ′∈[0,1], which conforms to the fitting equation: f(t i )=Φ T (t′ i )P i=1,2,…N In the formula, f(t i ) is t i The dynamic cooperation target discrete point position information corresponding to the moment (λ i γ i h i ); Φ(t) is the designed basis function, which is in polynomial form; P is the fitting coefficient of the polynomial, which is the unknown quantity; Satisfies the following linear equations: Where, F is the position information matrix; The fitting coefficient P is estimated using the least squares method of overdetermined equations: P=(Φ T F) -1 F T F After the fitting coefficient P is obtained, the fitting equation is obtained. The target planning posture tracking curve L is obtained by curve fitting the dynamic cooperative target discrete point sequence through the fitting equation.

5. The method for calculating the position information of dynamic cooperative targets by satellites with high precision and in real time according to claim 4, characterized in that: The formula of the basis function Φ(t) is: Φ(t)=(1 t t 2 t 3 t 4 t 5 t 6 t 7 t 8 t 9 t 10 t 11 t 12 ) T 。 6. The method for calculating the position information of dynamic cooperative targets by satellites with high precision and in real time according to claim 4, characterized in that: The target position information f(t0) at time t0 is: f(t0)=Φ T (t0′)P。 7. The method for calculating the position information of dynamic cooperative targets by satellites with high precision and in real time according to claim 6, characterized in that: The target position information f(t -5 )for: f(t -5 )=Φ T (t -5 ′)P。 8. The method for calculating the position information of dynamic cooperative targets by satellites with high precision and in real time according to claim 7, characterized in that: When the satellite maneuvers to its correct position, i When the dynamic cooperation target is between t0-5s and t0, the position f(t i )for:

9. The method for calculating the position information of dynamic cooperative targets by satellites with high precision and in real time according to claim 8, characterized in that: The least square method is based on the principle of minimum overall variance for curve fitting. Therefore, the fitting curve has high distortion at both ends, that is, the fitting error is large. If the fitting curve is used to calculate the target position from t0-5s to t0, obvious jitter will occur after reaching t0. Therefore, the linear interpolation method is used to achieve smooth switching of the satellite from the staring state to the guidance tracking state.

10. The method for calculating the position information of dynamic cooperative targets by satellites with high precision and in real time according to claim 7, characterized in that: When the satellite maneuvers to its correct position, i Between time t0 and t f At the time between the moments, the position of the dynamic cooperation target f(t i ) is calculated according to the target planning posture tracking curve L: f(t i )=Φ T (t i ′)P。

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