A sensorless coordinated control method for rapid zero crossing of momentum wheels in a redundant momentum wheel system

Abstract

This invention relates to the field of satellite attitude and orbit control technology, and particularly to a seamless coordinated control method for rapid zero-crossing of momentum wheels in a redundant momentum wheel system. The method includes the following steps: First, the trend of momentum wheel speed change is determined based on the variation in momentum wheel speed; second, the zero-crossing state of the momentum wheels is determined by combining the speed change trend and the measured speed of the momentum wheels; finally, based on the zero-motion characteristic of the momentum wheel assembly, a zero-crossing compensation torque is applied to the momentum wheel in the zero-crossing state to rapidly pass through the zero-crossing speed range, while a reverse compensation torque is applied to the other momentum wheels to make the resultant torque of the momentum wheel assembly zero. By increasing the zero-crossing compensation torque, the momentum wheel speed rapidly passes through the zero-crossing range, reducing the impact of momentum wheel speed zero-crossing on the satellite attitude control accuracy. This method can be extended to all satellites with momentum wheel speed zero-crossing conditions and high attitude control accuracy requirements.

Description

Technical Field

[0001] This invention relates to the field of satellite attitude and orbit control technology, and in particular to a sensorless coordinated control method for rapid zero crossing of momentum wheels in a redundant momentum wheel system. Background Technology

[0002] High-orbit SAR satellites are equipped with large-aperture deployable antennas. The cumulative and fluctuating angular momentum caused by the satellite's gravity gradient torque and solar pressure torque is large. The momentum wheel experiences two zero-speed crossings within one orbital cycle. The control dead zone when the momentum wheel speed crosses zero will cause the satellite's attitude control accuracy to fail to meet the requirements. Summary of the Invention

[0003] The purpose of this invention is to provide a sensorless coordinated control method for the rapid zero-crossing of momentum wheels in a redundant momentum wheel system, thereby reducing the impact of the zero-crossing of momentum wheel speed on attitude control accuracy.

[0004] To achieve the above objectives, this invention provides a sensorless coordinated control method for rapid zero-crossing of momentum wheels in a redundant momentum wheel system, comprising the following steps:

[0005] S1. Determine the trend of the momentum wheel's rotational speed based on the changes in the momentum wheel's rotational speed;

[0006] S2. Determine the zero-crossing state of the momentum wheel by combining the trend of the rotational speed change and the measured rotational speed of the momentum wheel;

[0007] S3. Based on the zero-motion characteristic of the momentum wheel assembly, apply a zero-crossing compensation torque to the momentum wheel in the zero-crossing state to make it quickly pass through the zero-speed range. At the same time, apply a reverse compensation torque to the other momentum wheels to make the resultant torque of the compensation torque of the momentum wheel assembly zero.

[0008] Optionally, the trend of change in the momentum wheel speed can be categorized as increasing, decreasing, or remaining constant;

[0009] The momentum wheel's zero-crossing state is divided into positive zero-crossing, negative zero-crossing, and not crossing zero.

[0010] Optionally, the process for determining the trend of momentum wheel speed change is as follows:

[0011] S11. Calculate the difference between the current cycle momentum wheel speed and the previous cycle momentum wheel speed: deltaS = SP T -SP T-1 SP T SP is the speed of the momentum wheel in this cycle. T-1 This represents the speed of the momentum wheel in the previous cycle.

[0012] S12. If deltaS is greater than the judgment threshold Hlmt, increment the speed change counter N by 1 and proceed to step S15; otherwise, proceed to step S13.

[0013] S13, if deltaS is less than a judgment threshold - Hlmt, then the speed change counter N is reduced by 1 and step S15 is turned to, otherwise step S14 is turned to;

[0014] S14, if N is greater than 0, then N is reduced by 1, if N is less than 0, then N is increased by 1, otherwise N is unchanged;

[0015] S15, according to the calculation results of steps S12-S14, if N = Nlmt, then the momentum wheel speed change trend flag Dir = 1, the momentum wheel speed change trend is divided into increasing;

[0016] if N = -Nlmt, then the momentum wheel speed change trend flag Dir = -1, the momentum wheel speed change trend is divided into decreasing;

[0017] if N = 0, then the momentum wheel speed change trend flag Dir = 0, the momentum wheel speed change trend is divided into stable.

[0018] Optionally, the judgment step of the zero-crossing state of the momentum wheel is as follows:

[0019] S21, the absolute value of the speed S Min of the momentum wheel with the minimum speed is calculated; Min ;

[0020] S22, if -M lmt <S Min <M lmt , and the corresponding momentum wheel speed change trend is increasing, then the momentum wheel zero-crossing state flag is positive zero-crossing;

[0021] if -M lmt <S Min <M lmt , and the corresponding momentum wheel speed change trend is decreasing, then the momentum wheel zero-crossing state flag is negative zero-crossing;

[0022] otherwise, the momentum wheel zero-crossing state flag is not zero-crossing;

[0023] wherein, M lmt and -M lmt are the upper threshold and the lower threshold of the momentum wheel speed zero-crossing interval respectively. Optionally, the step of applying a zero-crossing compensation torque to the momentum wheel in the zero-crossing state is as follows:

[0024] S31, if the momentum wheel speed zero-crossing flag is positive zero-crossing, then a positive direction control torque is applied to the zero-crossing momentum wheel until the momentum wheel speed exceeds the upper threshold M lmt of the zero-crossing interval;

[0025] If the momentum wheel rotation speed zero-crossing sign is negative, the zero-crossing momentum wheel compensation negative control torque is applied until the momentum wheel rotation speed exceeds the lower threshold -M of the zero-crossing interval lmt ;

[0026] S32, according to the momentum wheel installation matrix, the compensation torque of other non-zero-crossing momentum wheels is calculated, so that the resultant torque of the compensation torques of the entire wheel train is zero, and the compensation torque calculation method of the non-zero-crossing momentum wheel is as follows:

[0027] T AC =-(C Aw ) T ·inv(C Aw (C Aw ) T )·C Zw ·T c

[0028] Wherein, T AC is an (n-1) × 1 vector composed of compensation torques of other non-zero-crossing momentum wheels in the wheel train (n is the number of momentum wheels in the momentum wheel group), C Zw is the installation vector of the zero-crossing momentum wheel (3 × 1), C Aw is a matrix composed of installation vectors of other non-zero-crossing momentum wheels (3 × (n-1)) and is full rank, Tc is the compensation torque size (scalar) required by the zero-crossing momentum wheel, and the superscript T represents matrix transposition.

[0029] Optionally, the momentum wheel installation matrix is a 3 × n matrix, wherein n is the number of momentum wheels.

[0030] The above technical solutions of the present application have the following advantages:

[0031] The present application provides a kind of redundant momentum wheel train under momentum wheel fast zero-crossing inductive coordination control method, comprising the following steps: first, according to the change of momentum wheel rotation speed, the change trend of momentum wheel rotation speed is judged;Second, the zero-crossing state of momentum wheel is judged in combination with the change trend of rotation speed and the measured rotation speed of momentum wheel;Finally, based on the characteristics of momentum wheel group zero motion, zero-crossing compensation torque is applied to the momentum wheel in zero-crossing state to make it quickly pass through the rotation speed zero-crossing interval, and reverse compensation torque is applied to other momentum wheels to make the resultant torque of the compensation torques of the momentum wheel group zero.By increasing the zero-crossing compensation torque, the rotation speed of the momentum wheel quickly passes through the zero-crossing interval, and the influence of the rotation speed zero-crossing of the momentum wheel on the attitude control accuracy of the satellite is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0032] The drawings of the present application are provided for illustrative purposes only, and the proportions and quantities of the components in the drawings may not be consistent with the actual product.

[0033] Figure 1 is the flow chart of the fast zero-crossing control of the momentum wheel in the embodiment of the present application;

[0034] Figure 2 is a momentum wheel rotation speed change trend determination process in an embodiment of the present application. DETAILED DESCRIPTION

[0035] To make the objectives, technical solutions, and advantages of embodiments of the present application clearer, the following will be combined with the accompanying drawings for a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0036] As shown in Figure 1 , the present application provides a kind of inductive coordination control method for momentum wheel rapid zero-crossing under redundant momentum wheel system, it is applied to the satellite with momentum wheel rotation speed zero-crossing working condition, this method comprises the following steps:

[0037] S1, the change trend of momentum wheel rotation speed is determined according to the current value and historical value of momentum wheel rotation speed, wherein the change trend of momentum wheel rotation speed is divided into three states of increase, decrease and smooth.

[0038] S2, on the basis of momentum wheel rotation speed trend judgment, the zero-crossing state of momentum wheel is judged according to the current measured rotation speed of momentum, wherein the zero-crossing state of momentum wheel is divided into three states of positive zero-crossing (from negative rotation speed to positive rotation speed), negative zero-crossing (from positive rotation speed to negative rotation speed) and non-zero-crossing;

[0039] S3, the control torque of momentum wheel is compensated according to the judgment result of step S2 momentum wheel zero-crossing state, so that the momentum wheel in zero-crossing interval quickly passes through rotation speed zero-crossing interval, and the disturbance of momentum wheel static friction torque to satellite attitude is reduced.

[0040] In an example, the flow of momentum wheel rotation speed change trend judgment is as follows:

[0041] S11, the difference deltaS=SP T -SP T-1 is calculated, wherein SP T is the current period momentum wheel rotation speed, SP T-1 is the last period momentum wheel rotation speed;

[0042] S12, if deltaS is greater than judgment threshold Hlmt, the rotation speed change counter N is added by 1 and step S15 is turned, otherwise step S13 is turned;

[0043] S13, if deltaS is less than a judgment threshold - Hlmt, decrease the rotation speed change counter N by 1 and go to step S15, otherwise go to step S14;

[0044] S14, if N is greater than 0, decrease N by 1, if N is less than 0, increase N by 1, otherwise N remains unchanged;

[0045] S15, according to the calculation results of steps S12-S14, if N=Nlmt, the momentum wheel rotation speed change trend flag Dir=1, the momentum wheel rotation speed change trend is increasing;

[0046] if N=-Nlmt, the momentum wheel rotation speed change trend flag Dir=-1, the momentum wheel rotation speed change trend is decreasing;

[0047] if N=0, the momentum wheel rotation speed change trend flag Dir=0, the momentum wheel rotation speed change trend is stable.

[0048] In an example, the judgment step of the zero-crossing state of the momentum wheel is as follows:

[0049] S21, calculate the rotation speed S of the momentum wheel with the minimum absolute value of rotation speed Min and the corresponding momentum wheel number M Min ;

[0050] S22, if -M lmt <S Min <M lmt , and the corresponding momentum wheel rotation speed change trend is increasing, the momentum wheel zero-crossing state flag is positive zero-crossing;

[0051] if -M lmt <S Min <M lmt , and the corresponding momentum wheel rotation speed change trend is decreasing, the momentum wheel zero-crossing state flag is negative zero-crossing;

[0052] otherwise, the momentum wheel zero-crossing state flag is not zero-crossing;

[0053] wherein, M lmt and -M lmt are the upper threshold and lower threshold of the momentum wheel rotation speed zero-crossing interval respectively.

[0054] In an example, the step of applying a zero-crossing compensation torque to the momentum wheel in the zero-crossing state is as follows:

[0055] S31, if the momentum wheel rotation speed zero-crossing flag is positive zero-crossing, apply a positive direction control torque to the zero-crossing momentum wheel until the momentum wheel rotation speed exceeds the upper threshold M lmt of the zero-crossing interval;

[0056] If the momentum wheel rotation speed zero-crossing sign is negative, a negative zero-crossing momentum wheel compensation control torque is applied until the momentum wheel rotation speed exceeds the lower threshold value -M of the zero-crossing interval lmt ;

[0057] S32, according to the momentum wheel installation matrix (the installation matrix is a 3x n matrix, wherein n is the number of momentum wheels), the compensation torques of other non-zero-crossing momentum wheels are calculated to make the resultant torque of the compensation torques of the entire wheel system zero, and the compensation torque calculation method of the non-zero-crossing momentum wheels is as follows:

[0058] T AC =-(C Aw ) T ·inv(C Aw (C Aw ) T )·C Zw ·T c

[0059] Wherein, T AC is an (n-1) x 1 vector composed of compensation torques of other non-zero-crossing momentum wheels in the wheel system (n is the number of momentum wheels in the momentum wheel group), C Zw is the installation vector of the zero-crossing momentum wheel (3x1), C Aw is a matrix composed of installation vectors of other non-zero-crossing momentum wheels (3x (n-1)) and is full rank, Tc is the compensation torque size (scalar) required by the zero-crossing momentum wheel, and the superscript T represents matrix transposition.

[0060] In summary, the satellite uses the momentum wheel for attitude control in the normal working mode, the application designs a non-inductive coordinated control method for rapid zero-crossing of the momentum wheel under the redundant momentum wheel system, the method makes the momentum wheel rotation speed quickly pass through the zero-crossing interval by increasing the zero-crossing compensation torque, and reduces the influence of the momentum wheel rotation speed zero-crossing on the satellite attitude control accuracy. First, the change trend of the momentum wheel rotation speed is judged according to the change of the momentum wheel rotation speed. Secondly, the zero-crossing state of the momentum wheel is judged in combination with the rotation speed change trend and the measured rotation speed of the momentum wheel. Finally, based on the zero motion characteristics of the momentum wheel group, a zero-crossing compensation torque is applied to the momentum wheel in the zero-crossing state to make it quickly pass through the rotation speed zero-crossing interval, and a reverse compensation torque is applied to other momentum wheels to make the resultant torque of the compensation torques of the momentum wheel group zero. The method can be applied to all satellites with momentum wheel rotation speed zero-crossing working conditions and high attitude control accuracy requirements.

[0061] It should be noted that how to compensate the control torque to the momentum wheel is the existing technology in the field, which will not be repeated here.

[0062] The places not fully described in the application are the common knowledge or existing technology in the field.

[0063] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not intended to limit the same; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that not every example contains only one independent technical solution, and in the absence of solution conflicts, various technical features mentioned in each example can be combined in any manner to form other embodiments that can be understood by those skilled in the art.

[0064] In addition, modifications can be made to the technical solutions described in the foregoing examples, or equivalent replacements can be made to part of the technical features, without departing from the scope of the present application, so that the essence of the corresponding technical solution does not deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for inductive coordination control of fast zero-crossing of a momentum wheel under a redundant momentum wheel system, characterized in that, The method comprises the following steps: S1, judging the change trend of the momentum wheel rotation speed according to the change of the momentum wheel rotation speed; S2, judging the zero-crossing state of the momentum wheel in combination with the rotation speed change trend and the measured rotation speed of the momentum wheel; S3, based on the characteristic of zero motion of the momentum wheel set, exerting a zero-crossing compensation torque on the momentum wheel in the zero-crossing state to make it quickly pass through the rotation speed zero-crossing interval, and exerting a reverse compensation torque on other momentum wheels to make the resultant torque of the compensation torques of the momentum wheel set zero; The momentum wheel rotation speed change trend is divided into increasing, decreasing and stable; The momentum wheel zero-crossing state is divided into positive zero-crossing, negative zero-crossing and non-zero-crossing; The flow of the momentum wheel rotation speed change trend judgment is as follows: S11, calculate the difference deltaS = SP T - SP T-1 , where SP T is the current period momentum wheel speed, and SP T-1 is the previous period momentum wheel speed; S12, if deltaS is greater than the judgment threshold Hlmt, the rotation speed change counter N is increased by 1 and step S15 is transferred, otherwise step S13 is transferred; S13, if deltaS is less than the judgment threshold -Hlmt, the rotation speed change counter N is decreased by 1 and step S15 is transferred, otherwise step S14 is transferred; S14, if N is greater than 0, N is decreased by 1, if N is less than 0, N is increased by 1, otherwise N is unchanged; S15, according to the calculation results of steps S12-S14, if N=Nlmt, the momentum wheel rotation speed change trend flag Dir=1, the momentum wheel rotation speed change trend is divided into increasing; If N=-Nlmt, the momentum wheel rotation speed change trend flag Dir=-1, the momentum wheel rotation speed change trend is divided into decreasing; If N=0, the momentum wheel rotation speed change trend flag Dir=0, the momentum wheel rotation speed change trend is divided into stable.

2. The method of claim 1, wherein: The judgment step of the zero-crossing state of the momentum wheel is as follows: S21, calculate the absolute value of the minimum speed of the momentum wheel speed S Min and the corresponding momentum wheel number M Min ; S22, if -M lmt <S Min <M lmt And the corresponding momentum wheel rotation speed change trend is increasing, the momentum wheel zero-crossing state flag is positive zero-crossing. If -M lmt <S Min <M lmt , and the corresponding momentum wheel rotation speed change trend is decreasing, the momentum wheel zero-crossing state flag is negative zero-crossing. Otherwise, the momentum wheel zero-crossing state flag is non-zero-crossing; Wherein, M lmt and -M lmt are respectively upper and lower threshold values of the momentum wheel rotation speed in the zero-crossing interval.

3. The method of claim 1, wherein: The step of exerting a zero-crossing compensation torque on the momentum wheel in the zero-crossing state is as follows: S31, if the momentum wheel rotation speed zero-crossing flag is positive zero-crossing, a positive direction control torque is compensated for the zero-crossing momentum wheel until the momentum wheel rotation speed exceeds the upper threshold value M of the zero-crossing interval lmt ; If the momentum wheel rotation speed zero-crossing flag is negative, a negative control torque is applied to the zero-crossing momentum wheel compensation until the momentum wheel rotation speed exceeds the lower threshold -M of the zero-crossing interval lmt ; S32, according to the momentum wheel installation matrix, the compensation torques of other non-zero-crossing momentum wheels are calculated to make the resultant torque of the compensation torques of the entire wheel set zero, and the non-zero-crossing momentum wheel compensation torque calculation method is as follows: where, T AC is the (n-1) x 1 vector of compensation torques for the other non-zero-crossing momentum wheels in the train (n is the number of momentum wheels in the set), C Zw is the installation vector of the zero-crossing momentum wheel (3 x 1), C Aw is the matrix of installation vectors of the other non-zero-crossing momentum wheels (3 x (n-1)) and is full rank, Tc is the compensation torque magnitude (scalar) that the zero-crossing momentum wheel must provide, and the superscript T denotes matrix transpose.

4. The method of claim 3, wherein: The momentum wheel installation matrix is a 3×n matrix, wherein n is the number of momentum wheels in the momentum wheel set.

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