Satellite jet attitude control safety protection method and system based on energy function

Abstract

The invention discloses a satellite jet attitude control safety protection method based on an energy function, and the method can comprehensively judge whether the current jet has a fault or not and whether the jet limiting operation needs to be carried out or not through the jet cumulant and the change rate of the energy function along with the time, and can effectively avoid the increase of the jet cumulant caused by the disturbance torque of a satellite. The satellite can mistakenly execute the jet limiting operation under the condition that the jet fault does not occur, so that the attitude of the satellite is out of control, and disastrous consequences caused by satellite attitude divergence caused by the jet fault can be prevented. Particularly, the special parameter selection and judgment method based on the inequality is designed for the PD controller, a large amount of matrix operation is not needed, the calculation amount is small, few resources on the satellite are occupied, and practical application is easy.

Description

Technical Field

[0001] The present invention relates to the field of satellite control, and particularly to a satellite jet attitude control safety protection method based on an energy function. Background Art

[0002] Using chemical thrusters for jet attitude control is a common attitude control method for satellites. Jet attitude control has the advantages of simple control logic, large output torque, no angular momentum saturation limit, and can enable the satellite to perform rapid attitude maneuvers. However, when using jets for attitude control, the satellite no longer satisfies the constraint condition of angular momentum conservation. When the thruster fails or the control logic is incorrect, resulting in the jet control not being correctly executed, it is possible that the satellite keeps jetting in a single direction, the angular velocity gradually diverges, and finally the satellite disintegrates due to excessive angular velocity and other catastrophic consequences. Therefore, corresponding safety protection control methods must be designed on the satellite to prevent the situation of excessive satellite angular velocity caused by jet failures.

[0003] Currently, the jet protection method used on the satellite is mainly to perform limited jet control according to the cumulative amount of jets over time, that is, when the cumulative amount of jets in a certain direction exceeds the threshold, the jet control is stopped. However, this method has certain defects in practical applications. Due to the interference torque in the space environment where the satellite operates, and the large interference torque generated by orbit control jets when the satellite performs tasks such as orbit control, these will cause the cumulative amount of jets to gradually increase and exceed the threshold. Therefore, simply based on whether it exceeds the threshold for limited jet protection measures, it is very likely that the satellite jet control has not failed when the cumulative amount of jets exceeds the threshold, resulting in the control system wrongly performing limited jetting and causing the satellite to lose its attitude control ability. Summary of the Invention

[0004] The technical problem solved by the present invention is: overcoming the deficiencies of the prior art, proposing a satellite jet attitude control safety protection method based on an energy function, optimizing the existing jet control method, and avoiding the situation where the satellite wrongly executes satellite limited jet operation when the jet attitude control does not fail, resulting in the satellite losing attitude control.

[0005] The technical solution of the present invention is: a satellite jet attitude control safety protection method based on an energy function, including:

[0006] Establish an energy function that can characterize the current satellite jet attitude control trend; the energy function is established based on the satellite dynamics and kinematics equations and at the same time combined with the satellite control mode; the satellite jet attitude control trend includes satellite attitude convergence or divergence;

[0007] Establish an inequality condition, and select the parameters in the energy function according to the inequality condition;

[0008] Judge whether the accumulated jet amount of the satellite exceeds the threshold; include the judgment of the difference between positive and negative jets and the total jet amount; when the difference between positive and negative jets or the total jet amount exceeds the threshold, do not perform the jet limit operation, judge the rate of change of the energy function with time at this time, when the rate of change of the energy function with time is negative, continue with the jet attitude control; when the rate of change of the energy function with time is positive, perform the jet limit operation and stop the jet attitude control.

[0009] Furthermore, the energy function V is established as follows:

[0010]

[0011] In the formula, the attitude quaternion q = [q 0 q 13 T , q 13 = [q 1 q 2 q 3 , J is the inertia matrix of the satellite, ω is the projection vector of the angular velocity of the satellite relative to the inertial system in the body system; u is the control quantity; Q 1 , Q 2 , R are parameter matrices, and all are positive definite diagonal matrices.

[0012] Furthermore, the satellite adopts a PD controller; the energy function V is established as follows:

[0013]

[0014] In the formula, the attitude quaternion q = [q 0 q 13 T , q 13 = [q 1 q 2 q 3 , J is the inertia matrix of the satellite, ω is the projection vector of the angular velocity of the satellite relative to the inertial system in the body system; K p , K d are the control parameter matrices of the PD controller, Q 1 , Q 2 , R are parameter matrices, and all are positive definite diagonal matrices, Q 1 , Q 2 and R need to satisfy to make The superscript T represents the matrix transpose.

[0015] Furthermore, take Q 1 , Q 2 , R, J, K p , K d matrices to be all diagonal matrices,

[0016] ​​

[0017] Establish three inequality conditions described by polynomials:

[0018]

[0019] Make each element in the diagonal matrix satisfy the above inequalities.

[0020] Furthermore, the satellite judges the cumulative jet amounts in the three axes;

[0021] If any of the following conditions 1) to 3) is satisfied, it is determined that the difference between the positive and negative jets exceeds the threshold:

[0022] 1) The cumulative jet amount in the +X axis is greater than the cumulative jet amount in the -X axis by more than the threshold Tx_limit_plus, or the cumulative jet amount in the -X axis is greater than the cumulative jet amount in the +X axis by more than the threshold Tx_limit_minus;

[0023] 2) The cumulative jet amount in the +Y axis is greater than the cumulative jet amount in the -Y axis by more than the threshold Ty_limit_plus, or the cumulative jet amount in the -Y axis is greater than the cumulative jet amount in the +Y axis by more than the threshold Ty_limit_minus;

[0024] 3) The cumulative jet amount in the +Z axis is greater than the cumulative jet amount in the -Z axis by more than the threshold Tz_limit_plus, or the cumulative jet amount in the -Z axis is greater than the cumulative jet amount in the +Z axis by more than the threshold Tz_limit_minus;

[0025] If the following conditions are satisfied, it is determined that the total jet amount exceeds the threshold:

[0026] If the absolute value of the sum of the cumulative jet amounts in the positive and negative directions of the X axis exceeds the threshold Tx_limit, or the absolute value of the sum of the cumulative jet amounts in the positive and negative directions of the Y axis exceeds the threshold Ty_limit, or the absolute value of the sum of the cumulative jet amounts in the positive and negative directions of the Z axis exceeds the threshold Tz_limit.

[0027] The present invention also provides a satellite jet attitude control safety protection system based on an energy function, including:

[0028] The first module is used to establish an energy function that can characterize the current satellite jet attitude control trend; the energy function is established based on the satellite dynamics and kinematics equations and combines the satellite control mode; the satellite jet attitude control trend includes satellite attitude convergence or divergence;

[0029] The second module is used to establish inequality conditions and select parameters in the energy function according to the inequality conditions;

[0030] The third module is used to determine whether the cumulative jet amount of the satellite exceeds the threshold; it includes the judgment of the difference between positive and negative jets and the total jet amount; when the difference between positive and negative jets or the total jet amount exceeds the threshold, the jet limit operation is not performed, and the change rate of the energy function at this time is judged. When the change rate of the energy function is negative, the jet attitude control continues. When the change rate of the energy function is positive, the jet limit operation is performed and the jet attitude control is stopped.

[0031] Further, in the first module, the attitude is described by quaternions, and the satellite dynamics and kinematics equations are established; the energy function V is established as follows:

[0032]

[0033] In the formula, the attitude quaternion q = [q 0 q 13 T , q 13 = [q 1 q 2 q 3 , J is the satellite's moment of inertia matrix, ω is the projection vector of the satellite's angular velocity relative to the inertial system in the body system; u is the control quantity; Q 1 , Q 2 , R are parameter matrices, and all are positive definite diagonal matrices.

[0034] Further, in the first module, the satellite adopts a PD controller; the energy function V is established as follows:

[0035]

[0036] In the formula, the attitude quaternion q = [q 0 q 13 T , q 13 = [q 1 q 2 q 3 , J is the satellite's moment of inertia matrix, ω is the projection vector of the satellite's angular velocity relative to the inertial system in the body system; K p , K d are the control parameter matrices of the PD controller, Q 1 , Q 2 , R are parameter matrices, and all are positive definite diagonal matrices, Q 1 , Q 2 and R need to satisfy The superscript T represents the matrix transpose.

[0037] Further, in the second module, Q 1 , Q 2 , R, J, K p , K​​d The matrices are all diagonal matrices,

[0038]

[0039] Establish three inequality conditions described by polynomials:

[0040]

[0041]

[0042] Make each element in the diagonal matrix satisfy the above inequalities.

[0043] Furthermore, in the third module, the satellite judges the cumulative jet amounts of the three axes;

[0044] If any of the following conditions 1) - 3) is satisfied, it is determined that the difference between the positive and negative jet amounts exceeds the threshold:

[0045] 1) The cumulative jet amount in the +X axis is greater than the cumulative jet amount in the -X axis by more than the threshold Tx_limit_plus, or the cumulative jet amount in the -X axis is greater than the cumulative jet amount in the +X axis by more than the threshold Tx_limit_minus;

[0046] 2) The cumulative jet amount in the +Y axis is greater than the cumulative jet amount in the -Y axis by more than the threshold Ty_limit_plus, or the cumulative jet amount in the -Y axis is greater than the cumulative jet amount in the +Y axis by more than the threshold Ty_limit_minus;

[0047] 3) The cumulative jet amount in the +Z axis is greater than the cumulative jet amount in the -Z axis by more than the threshold Tz_limit_plus, or the cumulative jet amount in the -Z axis is greater than the cumulative jet amount in the +Z axis by more than the threshold Tz_limit_minus;

[0048] If the following conditions are satisfied, it is determined that the total jet amount exceeds the threshold:

[0049] If the absolute value of the sum of the cumulative jet amounts in the positive and negative directions of the X axis exceeds the threshold Tx_limit, or the absolute value of the sum of the cumulative jet amounts in the positive and negative directions of the Y axis exceeds the threshold Ty_limit, or the absolute value of the sum of the cumulative jet amounts in the positive and negative directions of the Z axis exceeds the threshold Tz_limit.

[0050] The advantages of the present invention compared with the prior art are as follows:

[0051] (1) The present invention innovatively proposes satellite jet attitude control protection based on an energy function. By comprehensively judging whether there is a current jet failure and whether a jet limit operation is required through the jet accumulation and the rate of change of the energy function over time, it can effectively avoid the increase in jet accumulation caused by satellite disturbance torque, prevent the satellite from erroneously performing a jet limit operation when there is no jet failure, resulting in the loss of satellite attitude control, and also prevent catastrophic consequences caused by jet failure leading to satellite attitude divergence.

[0052] (2) The present invention designs an energy function that can characterize the current satellite jet attitude control trend, and designs a special parameter selection method for the energy function based on inequalities for the PD controller. Three inequalities described by polynomials are given. Through these inequalities, it can be judged whether the relevant parameters of the designed energy function meet the design requirements. There is no need for a large number of matrix operations, the calculation amount is small, the on-board resources occupied are few, and it is easy to be applied in practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 It is a schematic diagram of the jet safety protection judgment process in the method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0054] In order to better understand the technical solution of the present invention, the specific implementation manner of the present invention will be described below.

[0055] The method steps proposed by the present invention are as follows:

[0056] (1) Establish an energy function that can characterize the current satellite jet attitude control trend; the energy function is established based on the satellite dynamics and kinematics equations and combines the satellite control mode; the satellite jet attitude control trend includes satellite attitude convergence or divergence;

[0057] (2) Establish inequality conditions and select parameters in the energy function according to the inequality conditions;

[0058] (3) Judge whether the jet accumulation of the satellite exceeds the threshold; include the judgment of the difference between positive and negative jets and the total jet volume; when the difference between positive and negative jets or the total jet volume exceeds the threshold, do not perform the jet limit operation, judge the change speed of the energy function at this time. When the change speed of the energy function is negative, continue the jet attitude control. When the change speed of the energy function is positive, perform the jet limit operation and stop the jet attitude control.

[0059] The following gives a specific embodiment of the present invention:

[0060] (1) First, describe the attitude by quaternion and establish the satellite dynamics and kinematics equations when using a PD controller for control.

[0061] Let the quaternion be

[0062] q = [q 0 q 13 T

[0063] q 13 = [q 1 q 2 q 3

[0064] The satellite dynamics and kinematics equations are

[0065]

[0066]

[0067] where ω is the projection vector of the angular velocity of the satellite relative to the inertial frame in the body frame, J is the inertia matrix of the satellite, u is the PD control torque, and T d is the disturbance torque.

[0068] The expression of the PD controller is

[0069] u = -K p q 13 -K d ω

[0070] Design an energy function V in the following form:

[0071]

[0072] After substituting the PD controller, it becomes:

[0073]

[0074] where Q 1 , Q 2 and R are positive definite diagonal matrices. Q 1 , Q 2 and R need to satisfy that after substituting the PD controller,

[0075]

[0076] Specifically, the satellite attitude kinematics and dynamics equations can be simplified, that is

[0077]

[0078] According to the above simplified equations, when using PD control, the derivative of this energy function with respect to time is

[0079]

[0080] where ​​

[0081]

[0082] (2) Take the matrix in the energy function as a diagonal matrix, i.e.:

[0083]

[0084] For the PD controller, the following criteria for the selection of energy function parameters are given in the form of inequalities. Each element of the diagonal matrix satisfies the following inequalities:

[0085]

[0086] (3) When the satellite performs jet attitude control, the cumulative jet gas amounts of the three axes are judged. When the jet gas amount exceeds the set upper limit, the on-board software gives the corresponding jet gas limit flag. The jet gas limit flag includes two cases: the difference between the positive and negative jet gases exceeds the threshold and the total jet gas amount exceeds the threshold. Refer to Figure 1 as shown:

[0087] a) The difference between the positive and negative jet gases exceeds the threshold

[0088] When any of the following conditions is satisfied, the jet gas difference limit flag is given:

[0089] 1) The cumulative jet gas amount on the +X axis is greater than the cumulative jet gas amount on the -X axis by more than the threshold Tx_limit_plus, or the cumulative jet gas amount on the -X axis is greater than the cumulative jet gas amount on the +X axis by more than the threshold Tx_limit_minus;

[0090] 2) The cumulative jet gas amount on the +Y axis is greater than the cumulative jet gas amount on the -Y axis by more than the threshold Ty_limit_plus, or the cumulative jet gas amount on the -Y axis is greater than the cumulative jet gas amount on the +Y axis by more than the threshold Ty_limit_minus;

[0091] 3) The cumulative jet gas amount on the +Z axis is greater than the cumulative jet gas amount on the -Z axis by more than the threshold Tz_limit_plus, or the cumulative jet gas amount on the -Z axis is greater than the cumulative jet gas amount on the +Z axis by more than the threshold Tz_limit_minus.

[0092] b) The total jet gas amount exceeds the threshold

[0093] If the absolute value of the sum of the cumulative jet gas amounts in the positive and negative directions of the X axis exceeds the threshold Tx_limit, or the absolute value of the sum of the cumulative jet gas amounts in the positive and negative directions of the Y axis exceeds the threshold Ty_limit, or the absolute value of the sum of the cumulative jet gas amounts in the positive and negative directions of the Z axis exceeds the threshold Tz_limit, the total jet gas amount limit flag is given.

[0094] After the on-board software gives the jet gas limit flag, the derivative of the energy function is calculated according to the current attitude and angular velocity of the satellite According to Make a further judgment on the positive and negative values. When is a positive number, it indicates that the current satellite energy is divergent, and the jet attitude control cannot ensure the satellite attitude stability, so stop the jet control. When is a negative number, it indicates that the current jet control does not cause the satellite attitude to diverge. At this time, clear the corresponding jet accumulator according to the source of the limited jet flag, that is, start accumulating the jet volume from zero again, and at the same time clear the corresponding limited jet flag, and continue the jet attitude control.

[0095] The present invention also provides a satellite jet attitude control safety protection system based on an energy function, including:

[0096] The first module is used to establish an energy function that can characterize the current satellite jet attitude control trend; the energy function is established based on the satellite dynamics and kinematics equations and combined with the satellite control mode; the satellite jet attitude control trend includes satellite attitude convergence or divergence;

[0097] The second module is used to establish inequality conditions and select parameters in the energy function according to the inequality conditions;

[0098] The third module is used to judge whether the jet accumulation of the satellite exceeds the threshold; it includes the judgment of the difference between positive and negative jets and the total jet volume; when the difference between positive and negative jets or the total jet volume exceeds the threshold, do not perform the limited jet operation, judge the change speed of the energy function at this time, when the change speed of the energy function is negative, continue the jet attitude control, and when the change speed of the energy function is positive, perform the limited jet operation and stop the jet attitude control.

[0099] The specific functions of the modules can be realized depending on the foregoing methods.

[0100] It can be understood that the present invention is described through embodiments. As is known to those skilled in the art, without departing from the spirit and scope of the present invention, various changes or equivalent replacements can be made to these features and embodiments. In addition, under the teaching of the present invention, these features and embodiments can be modified to adapt to specific situations without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and the embodiments that can fall within the scope of the claims of this application all belong to the scope protected by the present invention.

[0101] The content not detailedly described in the specification of the present invention belongs to the well-known technology of those skilled in the art.

Claims

1. A satellite jet attitude control safety protection method based on energy function, characterized in that: include: Establish an energy function that can characterize the current satellite jet attitude control trend; The energy function is established based on satellite dynamics and kinematics equations combined with satellite control methods; the satellite jet attitude control trend includes satellite attitude convergence or divergence; Establish inequality conditions and select parameters in the energy function according to the inequality conditions; Determine whether the satellite's jet accumulation exceeds a threshold; Including the difference between positive and negative jets and the total jet volume judgment; When the difference between positive and negative jets or the total jet volume exceeds the threshold, the jet limiting operation is not performed, and the rate of change of the energy function over time is judged. When the rate of change of the energy function over time is negative, the jet attitude control continues; when the rate of change of the energy function over time is positive, the jet limiting operation is performed and the jet attitude control is stopped.

2. The satellite jet attitude control safety protection method based on energy function according to claim 1 is characterized in that: The energy function V is established as follows: Where, attitude quaternion q = [q0 q 13 ] T ,q 13 =[q1 q2 q3], J is the satellite's moment of inertia matrix, ω is the projection vector of the satellite's angular velocity relative to the inertial system within this system; u is the control quantity; Q1, Q2, R are parameter matrices, and all are positive definite diagonal matrices.

3. The satellite jet attitude control safety protection method based on energy function according to claim 1 is characterized in that: The satellite adopts a PD controller; the energy function V is established as follows: Where, attitude quaternion q = [q0 q 13 ] T ,q 13 =[q1 q2 q3], J is the satellite's moment of inertia matrix, ω is the projection vector of the satellite's angular velocity relative to the inertial system in this system; K p , K d is the control parameter matrix of the PD controller, Q1, Q2, and R are parameter matrices, and they are all positive definite diagonal matrices. Q1, Q2, and R need to satisfy The superscript T stands for matrix transpose.

4. The satellite jet attitude control safety protection method based on energy function according to claim 3 is characterized in that: Take Q1, Q2, R, J, K in the energy function p , K d The matrices are all diagonal matrices. Establish three inequality conditions described by polynomials: Make sure that each element in the diagonal matrix satisfies the above inequality.

5. The satellite jet attitude control safety protection method based on energy function according to claim 1 is characterized in that: The satellite determines the jet accumulation on three axes; If any of the following conditions 1) to 3) is met, the difference between positive and negative jets is considered to exceed the threshold: 1) The +X axis jet accumulation is greater than the negative -X jet accumulation by more than the threshold value Tx_limit_plus, or the -X jet accumulation is greater than the +X jet accumulation by more than the threshold value Tx_limit_minus; 2) The +Y axis jet accumulation is greater than the negative -Y jet accumulation by a threshold value Ty_limit_plus, or the -Y jet accumulation is greater than the +Y jet accumulation by a threshold value Ty_limit_minus; 3) The +Z axis jet accumulation is greater than the negative -Z jet accumulation by a threshold value Tz_limit_plus, or the -Z jet accumulation is greater than the +Z jet accumulation by a threshold value Tz_limit_minus; The total jet volume exceeds the threshold when the following conditions are met: If the absolute value of the sum of the positive and negative direction jet accumulation of the X axis exceeds the threshold value Tx_limit, or the absolute value of the sum of the positive and negative direction jet accumulation of the Y axis exceeds the threshold value Ty_limit, or the absolute value of the sum of the positive and negative direction jet accumulation of the Z axis exceeds the threshold value Tz_limit.

6. A satellite jet attitude control safety protection system based on energy function, characterized in that: include: The first module is used to establish an energy function that can characterize the current satellite jet attitude control trend; The energy function is established based on satellite dynamics and kinematics equations combined with satellite control methods; the satellite jet attitude control trend includes satellite attitude convergence or divergence; The second module is used to establish inequality conditions and select parameters in the energy function according to the inequality conditions; The third module is used to determine whether the satellite's jet accumulation exceeds a threshold; Including the judgment of the difference between positive and negative jets and the total jet volume; when the difference between positive and negative jets or the total jet volume exceeds the threshold, the jet limiting operation is not performed, and the change speed of the energy function at this time is judged. When the energy function change speed is negative, the jet attitude control continues. When the energy function change speed is positive, the jet limiting operation is performed and the jet attitude control is stopped.

7. The satellite jet attitude control safety protection system based on energy function according to claim 6 is characterized in that: In the first module, the attitude is described by quaternions, and the satellite dynamics and kinematics equations are established; the energy function V is established as follows: Where, attitude quaternion q = [q0 q 13 ] T ,q 13 =[q1 q2 q3], J is the satellite's moment of inertia matrix, ω is the projection vector of the satellite's angular velocity relative to the inertial system within this system; u is the control quantity; Q1, Q2, R are parameter matrices, and all are positive definite diagonal matrices.

8. The satellite jet attitude control safety protection system based on energy function according to claim 6 is characterized by: In the first module, the satellite adopts a PD controller; the energy function V is established as follows: Where, attitude quaternion q = [q0 q 13 ] T ,q 13 =[q1 q2 q3], J is the satellite's moment of inertia matrix, ω is the projection vector of the satellite's angular velocity relative to the inertial system in this system; K p , K d is the control parameter matrix of the PD controller, Q1, Q2, and R are parameter matrices, and they are all positive definite diagonal matrices. Q1, Q2, and R need to satisfy The superscript T stands for matrix transpose.

9. The satellite jet attitude control safety protection system based on energy function according to claim 8 is characterized in that: In the second module, take Q1, Q2, R, J, K in the energy function p , K d The matrices are all diagonal matrices. Establish three inequality conditions described by polynomials: Make sure that each element in the diagonal matrix satisfies the above inequality.

10. The satellite jet attitude control safety protection system based on energy function according to claim 6 is characterized by: In the third module, the satellite determines the jet accumulation in three axes; If any of the following conditions 1) to 3) is met, the difference between positive and negative jets is considered to exceed the threshold: 1) The +X axis jet accumulation is greater than the negative -X jet accumulation by more than the threshold value Tx_limit_plus, or the -X jet accumulation is greater than the +X jet accumulation by more than the threshold value Tx_limit_minus; 2) The +Y axis jet accumulation is greater than the negative -Y jet accumulation by a threshold value Ty_limit_plus, or the -Y jet accumulation is greater than the +Y jet accumulation by a threshold value Ty_limit_minus; 3) The +Z axis jet accumulation is greater than the negative -Z jet accumulation by a threshold value Tz_limit_plus, or the -Z jet accumulation is greater than the +Z jet accumulation by a threshold value Tz_limit_minus; The total jet volume exceeds the threshold when the following conditions are met: If the absolute value of the sum of the positive and negative direction jet accumulation of the X axis exceeds the threshold value Tx_limit, or the absolute value of the sum of the positive and negative direction jet accumulation of the Y axis exceeds the threshold value Ty_limit, or the absolute value of the sum of the positive and negative direction jet accumulation of the Z axis exceeds the threshold value Tz_limit.

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