A relative pointing tracking control method without aiming

Abstract

The present application discloses a relative pointing tracking control method under non-tracking conditions, including: measuring the current orbital parameters of the tracking satellite and the target satellite, and extrapolating the future orbital parameters; calculating the relative position and pointing angle data between the tracking satellite and the target satellite; fitting the fitting parameters and the corresponding time parameters and sending them to the tracking satellite, and calculating the relative pointing angle, relative pointing angular velocity, and relative pointing angular acceleration based on the fitting parameters and time parameters; performing an attitude bias based on the relative pointing angle at the starting moment, and when the onboard time reaches the starting moment of the relative pointing angle curve, controlling the tracking satellite to track the target satellite until the end moment of the relative pointing angle curve, and finally adjusting the flight attitude of the tracking satellite back to the ground pointing attitude. The relative pointing tracking control method under non-tracking conditions of the present application can achieve autonomous relative pointing control onboard the satellite in the event of failure of the onboard tracking and aiming equipment, thereby ensuring that the onboard payload performs its mission normally.

Description

Technical Field

[0001] The present application relates to a relative pointing tracking control method under non-aiming conditions. Background Art

[0002] With the increasing complexity and diversity of satellite missions in space, as well as the diversification and sophistication of satellite payload functionality, relative pointing tracking control is becoming an increasingly important requirement for satellites. Relative pointing tracking control is based on relative measurement. Relative measurement equipment (i.e., tracking and pointing equipment) measures the relative position between two satellites. The relative pointing angle, pointing angular velocity, and pointing angular acceleration of the two satellites are then calculated, using these as control inputs for relative pointing control of the satellites. If the onboard tracking and pointing equipment fails, the relative position information between the two satellites cannot be obtained, and the relative pointing control mission cannot be performed. Therefore, to ensure that the satellite can continue to perform relative pointing control missions even if all onboard tracking and pointing equipment fails, a relative pointing tracking control method is needed without tracking and pointing. Summary of the Invention

[0003] The purpose of the present invention is to provide a relative pointing tracking control method under non-tracking and aiming conditions, which has the advantage of being able to achieve satellite pointing tracking when the on-board tracking and aiming equipment cannot aim.

[0004] To achieve the above object, the present invention provides a relative pointing tracking control method without tracking and aiming, which comprises:

[0005] S10. The ground tracking and control station measures the current orbital parameters of the tracking satellite and the target satellite, and extrapolates the future orbital parameters based on the current orbital parameters.

[0006] S20, calculating the relative position between the tracking star and the target star in the orbital system of the tracking star according to the future orbital parameters, and calculating the pointing angle data of the target star relative to the tracking star;

[0007] S30, the ground measurement and control station performs a fitting operation on the pointing angle data to obtain fitting parameters, fitting coefficients and corresponding time parameters;

[0008] S40, sending the fitting parameters, fitting coefficients, and time parameters to the tracking satellite, wherein the tracking satellite calculates the relative pointing angle, relative pointing angular velocity, and relative pointing angular acceleration according to the fitting parameters, fitting coefficients, and time parameters;

[0009] S50, sending a relative pointing tracking task start command to the tracking satellite;

[0010] S60, performing attitude bias on the tracking star according to the relative pointing angle at the starting time, and when the onboard time of the tracking star reaches the starting time of the relative pointing angle curve, controlling the tracking star to track the target star according to the relative pointing angle, the relative pointing angular velocity, and the relative pointing angular acceleration;

[0011] S70: When the onboard time of the tracking satellite reaches the end time of the relative pointing angle curve, the flight attitude of the tracking satellite is adjusted to a zero attitude of the Earth orbit system.

[0012] Preferably, in step S30, the ground measurement and control station performs a fitting operation on the pointing angle data by using a least squares method.

[0013] Preferably, the fitting operation includes segmented fitting, and the segmented fitting includes the following steps:

[0014] S301, fitting the entire segment of the pointing angle data, and determining a maximum error point where a maximum fitting error occurs;

[0015] S302, calculating whether the error of the maximum error point meets the accuracy requirement, if yes, proceeding to S40; if not, proceeding to S303;

[0016] S303 , dividing the entire segment of the directional angle data into two segments with the maximum error point as a dividing point, and fitting the two segments of the directional angle data respectively.

[0017] Preferably, after step S303, the method further includes:

[0018] S304, obtaining a first fitting error and a second fitting error according to the fitting results of the two segments of the pointing angle data;

[0019] S305: Determine whether both the first fitting error and the second fitting error meet the accuracy requirement. If both meet the accuracy requirement, proceed to S40. If the first fitting error or the second fitting error does not meet the accuracy requirement, proceed to S306.

[0020] S306. Taking the maximum error point as the dividing point, taking one quarter of the entire segment of the pointing angle data on the left and right sides of the maximum error point to form a second segment, and the first segment and the third segment are located on both sides of the second segment respectively, and performing segmented fitting on the first segment, the second segment and the third segment respectively.

[0021] Preferably, in step S40, the relative pointing angular velocity is calculated by analytical derivation.

[0022] Preferably, in step S40, the relative pointing angular acceleration is calculated in the form of the pointing angular velocity difference.

[0023] Preferably, in step S60, the attitude control of the tracking star is performed by a method of feed-forward compensation of the pointing angular acceleration plus feedback control of the pointing angular velocity and pointing angle data.

[0024] Preferably, the pointing angle data includes a pointing pitch angle and an azimuth angle.

[0025] In summary, compared with the prior art, the relative pointing tracking control method without tracking and aiming provided by the present invention has the following beneficial effects:

[0026] The relative pointing tracking control method under the condition of no tracking and aiming in the present application can, when the on-board tracking and aiming equipment fails, measure the orbits of the tracking satellite and the target satellite through the ground measurement and control station and extrapolate the future orbital parameters, thereby realizing autonomous relative pointing control on the satellite and ensuring that the on-board payload performs its mission normally; in addition, the segmented fitting algorithm can effectively improve the fitting accuracy under mission conditions with large relative pointing angular velocity, thereby improving the relative pointing control accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a flow chart of the relative pointing tracking control method without tracking and aiming conditions. DETAILED DESCRIPTION

[0028] The following will be combined with the appended Figure 1 , the technical solutions, structural features, objectives achieved and effects in the embodiments of the present invention are described in detail.

[0029] It should be noted that the drawings are in a very simplified form and use non-precise proportions. They are only used to conveniently and clearly assist in explaining the embodiments of the present invention, and are not used to limit the conditions for the implementation of the present invention. Therefore, they have no substantive technical significance. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed in the present invention without affecting the efficacy and purpose that can be achieved by the present invention.

[0030] It should be noted that, in the present invention, relational terms such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only the elements explicitly listed, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0031] like Figure 1 As shown, the present invention provides a relative pointing tracking control method under non-tracking conditions, comprising:

[0032] S10. The ground tracking and control station measures the current orbital parameters of the tracking satellite and the target satellite and extrapolates the current orbital parameters to obtain future orbital parameters. The ground tracking and control station continuously measures the tracking satellite and the target satellite for a period of time to obtain high-precision orbital parameters for the tracking satellite and the target satellite. The ground tracking and control station then performs high-precision extrapolation of the orbits of the two satellites to obtain their orbital parameters for the future mission period. The target satellite is the satellite being tracked, and the tracking satellite is the satellite tracking the target satellite.

[0033] S20, calculate the relative position between the tracking star and the target star in the tracking star's orbital system based on the future orbital parameters, and calculate the pointing angle data of the target star relative to the tracking star, the pointing angle data includes the pointing pitch angle and azimuth angle. By using the orbital parameters of the tracking star and the target star, calculate the relative position of the two stars in the tracking star's orbital system. And calculate the pointing pitch angle α and azimuth angle β. The specific algorithm for pointing pitch angle α and azimuth angle β is as follows:

[0034] 1) Calculate the position and velocity vectors of the tracking star and the target star in the inertial system according to the orbital parameters of the tracking star and the target star (where the position vector and velocity vector of the tracking star are and The position vector and velocity vector of the target star are and ), calculating the position vector and velocity vector of the satellite based on the orbital parameters is an existing technology well known to those skilled in the art and will not be described in detail here.

[0035] 2) Calculate the coordinate transfer matrix A from the J2000 inertial system to the tracking star orbit system based on the orbital parameters oi .

[0036] 3) Calculate the relative position between the tracking star and the target star The calculation formula is as follows:

[0037]

[0038] 4) Calculate the pointing pitch angle α and azimuth angle β. The calculation formula is as follows:

[0039]

[0040] S30, the ground measurement and control station performs a fitting operation on the pointing angle data to obtain fitting parameters and corresponding time parameters. In this embodiment, the ground measurement and control station performs a fitting operation on the pointing angle data by the least squares method. The ground measurement and control station performs a fitting operation on the pointing pitch angle α(k) and azimuth angle β(k) within the future mission time period by the least squares method with time t as the independent variable. The fitting operation includes segmented fitting. Segmented fitting can improve the fitting accuracy. If segmentation is not performed, the accuracy requirements may not be met when the pointing angle changes rapidly. In this embodiment, the entire pointing angle data is divided into three segments at most for fitting, and the fitting parameters and fitting coefficients of the first segment, the second segment, and the third segment are preset before fitting. The specific fitting process is as follows:

[0041] S301. Fit the entire pointing angle data and determine the maximum error point where the maximum fitting error occurs. First, take N data points at equal intervals from the relative pointing angle data within the entire mission time period for fitting. The fitting function is shown as follows:

[0042] Z(i)=A i0 +A i1 sin(nt)+A i2 sin(nt)+A i3 sin(2nt)+A i4 sin(2nt)+A i5 sin(3nt)+A i6 sin(3nt)+A i7 sin(t)+A i8 ·tsin(nt)+A i9 ·tsin(nt),i=1,2··

[0043] Where Z = [α β], A i0 , A i1 ,…,A i8 , A i9 is the fitting coefficient pointing to the elevation angle α or azimuth angle β.

[0044] The fitting parameter is n=27π / (t f -t0), where t0 represents the starting time of the pointing angle data, t f Represents the final moment of the pointing angle data, and the fitting coefficient of the first segment is obtained as:

[0045]

[0046] S302, calculate whether the error of the maximum error point meets the accuracy requirement, if yes, go to S40; if not, go to S303.

[0047] Determine whether the fitting coefficients calculated in S301 meet the fitting accuracy requirements. Calculate the pointing pitch angle α′1(k) and azimuth angle β′1(k) within the mission time period based on the calculation results obtained in S301. The calculation formula is as follows:

[0048]

[0049] where t k is the time corresponding to the kth beat.

[0050] Then calculate the difference between the fitting result and the original data. The calculation formula is as follows:

[0051] Δα1(k)=α′1(k)-α(k)

[0052] Δβ1(k)=β′1(k)-β(k)

[0053] Determine whether the absolute values ​​of the maximum values ​​of Δα1(k) and Δβ1(k) meet the fitting requirements (i.e., whether the absolute values ​​of the maximum values ​​of Δα1(k) and Δβ1(k) are less than the required error value). The fitting requirements are determined in advance, for example, 0.1°. The fitting requirements can be determined according to actual needs. If the absolute values ​​of the maximum values ​​of Δα1(k) and Δβ1(k) meet the accuracy requirements, the fitting is completed and the fitting coefficients of the second segment are set.

[0054]

[0055] and the fitting coefficient of the third segment

[0056]

[0057] The fitting parameters n2 and n3 of the second and third segments are both assigned 0. The time dividing point t1 between the first and second segments, and the time dividing point t2 between the second and third segments are both assigned t f , that is, all pointing angle data are taken as the first segment for fitting. If the absolute value of the maximum value of Δα1(k) and Δβ1(k) does not meet the requirements, then go to S303.

[0058] S303, divide the entire segment of pointing angle data into two segments with the maximum error point as the dividing point, and fit the two segments of pointing angle data separately. Find the time point t corresponding to msx(abs(Δα1(k), Δβ1(k))) max , with t max As the dividing point, the time period [t0, t max ] and [t max , t f ] are fitted with the pointing pitch angle α(k) and azimuth angle β(k) in the same way as in the previous step. After fitting, the fitting coefficients of the first and second segments are obtained.

[0059]

[0060] And the fitting parameters of the first and second segments n1=2π / (t max -t0), n2=2π / (t f -t max ).

[0061] S304: Obtain a first fitting error and a second fitting error based on the fitting results of the two segments of pointing angle data. Calculate the pointing pitch angle α′2(k) and azimuth angle β′2(k) within the mission time period based on the calculation results obtained in S303. The calculation formula is as follows:

[0062]

[0063] Then calculate the difference between the fitted result and the original data:

[0064] Δα2(k)=α′2(k)-α(k)

[0065] Δβ2(k)=β′2(k)-β(k)

[0066] S305. Determine whether both the first fitting error and the second fitting error meet the accuracy requirements. If they do, proceed to S40. If the first fitting error or the second fitting error does not meet the accuracy requirements, proceed to S306. In this embodiment, the maximum absolute value of Δα2(k) is the first fitting error, and the maximum absolute value of Δβ2(k) is the second fitting error. Determine whether the maximum absolute values ​​of Δα2(k) and Δβ2(k) meet the fitting accuracy requirements. If they do, the fitting ends and the third fitting coefficient is set as

[0067]

[0068] and fitting parameter n3 are assigned to 0, and t1 = t max , t2=t f If the requirements are not met, proceed to step S306.

[0069] S306, taking the maximum error point as the dividing point, take a quarter of the entire segment of the pointing angle data on both sides of the maximum error point to form the second segment, and the first and third segments are located on both sides of the second segment respectively. Perform segment fitting on the first, second and third segments respectively. The entire mission time period is divided into three segments, namely [t0, t1], [t1, t2], and [t2, t3], where t1 = t max -(t max -t0) / 4, t2=t max +(t f -t max ) / 4, that is, tmax As the split point, take a quarter of the segments before and after as the second segment, and the remaining two segments before and after are the first and third segments respectively. Then fit the pointing angle data of these three segments respectively, using the same fitting method as the previous method, and get the coefficients of the first, second and third segments:

[0070]

[0071]

[0072] And the fitting parameters of the first, second and third segments are n1=2π / (t1-t0), n2=2π / (t2-t1), n3=2π / (t f -t2).

[0073] S40. Send the fitting parameters, fitting coefficients, and time parameters to the tracking satellite. The amount of pointing pitch and azimuth angle data calculated on the ground is too large to be directly transmitted to the satellite. By transmitting the fitting parameters, fitting coefficients, and time parameters, the amount of parameters transmitted can be effectively reduced. The tracking satellite calculates the relative pointing angle, relative pointing angular velocity, and relative pointing angular acceleration based on the fitting parameters and time parameters. The method for calculating the relative pointing angle is as follows:

[0074]

[0075] where α u (k) is the pointing pitch angle calculated on the tracking satellite, β u (k) is the azimuth angle calculated on board the satellite.

[0076] According to the calculation, the pointing pitch angle α u (k) and azimuth angle β u (k) Calculate the pointing pitch angular velocity and azimuthal velocity The calculation method is as follows:

[0077]

[0078] According to the calculated pointing pitch angular velocity and azimuthal velocity Calculate pointing and pitching acceleration and azimuthal acceleration In this embodiment, the angular velocity difference is used for calculation, and the calculation method is as follows:

[0079]

[0080]

[0081] Where (k-1) represents the value of the previous beat, and (k) represents the value of the current beat.

[0082] S50: Send a relative pointing tracking task start command to the tracking satellite.

[0083] S60: The tracking satellite performs an attitude offset based on the relative pointing angle at the starting time. When the tracking satellite's onboard time reaches the starting time of the relative pointing angle curve, the tracking satellite is controlled to point toward the target satellite based on the relative pointing angle, relative pointing angular velocity, and relative pointing angular acceleration calculated in step S40. The pointing angle curve plots the relative pointing angle between the tracking satellite and the target satellite over time. The starting and ending times of the pointing angle curve are determined when the ground tracking and control station transmits this information to the satellite. In this embodiment, the tracking satellite's attitude is controlled to point toward the target satellite through feedforward compensation of pointing angular acceleration combined with feedback control of pointing angular velocity and pointing angle data.

[0084] S70: When the onboard time of the tracking satellite reaches the end moment of the relative pointing angle curve, the flight attitude of the tracking satellite is adjusted to the zero attitude of the Earth orbit system.

[0085] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description is not intended to limit the present invention. After reading the above description, various modifications and substitutions of the present invention will become apparent to those skilled in the art. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A relative pointing tracking control method without tracking and aiming, characterized in that: The control method includes: S10. The ground tracking and control station measures the current orbital parameters of the tracking satellite and the target satellite, and extrapolates the future orbital parameters based on the current orbital parameters. S20, calculating the relative position between the tracking star and the target star in the orbital system of the tracking star according to the future orbital parameters, and calculating the pointing angle data of the target star relative to the tracking star; S30, the ground measurement and control station performs a fitting operation on the pointing angle data to obtain fitting parameters, fitting coefficients and corresponding time parameters; The fitting operation includes piecewise fitting, and the piecewise fitting includes the following steps: S301, fitting the entire segment of the pointing angle data, and determining a maximum error point where a maximum fitting error occurs; S302, calculating whether the error of the maximum error point meets the accuracy requirement, if yes, proceeding to S40; if not, proceeding to S303; S303, dividing the entire segment of the pointing angle data into two segments with the maximum error point as a dividing point, and fitting the two segments of the pointing angle data respectively; After step S303, the method further includes: S304, obtaining a first fitting error and a second fitting error according to the fitting results of the two segments of the pointing angle data; S305: Determine whether both the first fitting error and the second fitting error meet the accuracy requirement. If both meet the accuracy requirement, proceed to S40. If the first fitting error or the second fitting error does not meet the accuracy requirement, proceed to S306. S306: Taking the maximum error point as the dividing point, taking one-quarter of the whole segment of pointing angle data on both sides of the maximum error point to form a second segment, and the first segment and the third segment are located on both sides of the second segment respectively, and performing segmented fitting on the first segment, the second segment, and the third segment respectively. S40, sending the fitting parameters, fitting coefficients, and time parameters to the tracking satellite, wherein the tracking satellite calculates the relative pointing angle, relative pointing angular velocity, and relative pointing angular acceleration according to the fitting parameters, fitting coefficients, and time parameters; S50, sending a relative pointing tracking task start command to the tracking satellite; S60, performing attitude bias on the tracking star according to the relative pointing angle at the starting time, and when the onboard time of the tracking star reaches the starting time of the relative pointing angle curve, controlling the tracking star to track the target star according to the relative pointing angle, the relative pointing angular velocity, and the relative pointing angular acceleration; S70: When the onboard time of the tracking satellite reaches the end time of the relative pointing angle curve, the flight attitude of the tracking satellite is adjusted to a zero attitude of the Earth orbit system.

2. The relative pointing tracking control method without tracking and aiming as claimed in claim 1, characterized in that: In step S30, the ground measurement and control station performs a fitting operation on the pointing angle data by using a least squares method.

3. The relative pointing tracking control method without tracking and aiming as claimed in claim 1, characterized in that: In step S40, the relative pointing angular velocity is calculated by analytical derivation.

4. The relative pointing tracking control method without tracking and aiming as claimed in claim 1, wherein: In step S40, the relative pointing angular acceleration is calculated in the form of the relative pointing angular velocity difference.

5. The relative pointing tracking control method without tracking and aiming as claimed in claim 1, characterized in that: In step S60, the attitude control of the tracking star is performed by the relative pointing angular acceleration feedforward compensation plus the relative pointing angular velocity and pointing angle data feedback control.

6. The relative pointing tracking control method without tracking and aiming as claimed in claim 1, wherein: The pointing angle data includes a pointing elevation angle and an azimuth angle.

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