Momentum management method for momentum wheel of micro-nano satellite

Abstract

The invention discloses a momentum management method for momentum wheels of a micro-nano satellite, which is a momentum management method for a specific reaction wheel device (four momentum wheels), and particularly aims at slowly reducing the rotating speed of the momentum wheels when the momentum wheels of the momentum wheel device using the four momentum wheels at the same time keep stable rotating speed in a stable state. By the adoption of the method, on the premise that normal torque output of the momentum wheel is not affected, the rotating speed of the momentum wheel in the posture stable state can be effectively reduced, so that power consumption of the momentum wheel is reduced, and it is guaranteed that the momentum wheel has enough torque output.

Description

Technical Field

[0001] The present invention relates to a momentum management method for a micro-nano satellite momentum wheel used for micro-nano satellite attitude control, which is used to reduce the rotation speed of the momentum wheel in an uncontrolled state. Background Art

[0002] Existing methods for controlling the attitude of micro-nanosatellites typically use three orthogonal momentum wheels, with a diagonally mounted wheel serving as a backup, deployed only when one of the three orthogonal wheels fails. To effectively improve the controllability of the momentum wheels, four can be used simultaneously. However, when all four are used simultaneously, due to saturation limitations, the wheels will continue to rotate even when the attitude is stable. This not only increases the power consumption of the momentum wheels but also affects their controllability. Summary of the Invention

[0003] To address the shortcomings of the aforementioned background technologies, the present application provides a momentum management method for a micro-nano satellite momentum wheel. This method can effectively reduce the power consumption of the momentum wheel and ensure sufficient torque output from the momentum wheel. The present invention is implemented using the following technical solutions:

[0004] A momentum management method for a micro-nano satellite momentum wheel is used to manage the momentum of the momentum wheel in a stable attitude state, comprising the following steps:

[0005] (1) According to the installation of the momentum wheel device on the satellite, the torque distribution matrix C in the satellite body coordinate system is obtained: m The function of the torque distribution matrix in the satellite body coordinate system is to distribute the control torque of each momentum wheel to the x, y, and z axes of the satellite body coordinate system.

[0006] The torque distribution matrix C in the satellite body coordinate system m The specific calculation method is:

[0007] When the momentum wheel is installed on the satellite, there will be a certain conversion relationship between the momentum wheel coordinate system and the satellite body coordinate system. The conversion relationship between the two is the installation matrix A I (3×3 matrix).

[0008] According to the rotation direction of each momentum wheel in the momentum wheel coordinate system, the momentum wheel torque (4×1 vector) is converted to the momentum wheel coordinate system (3×1 vector). This conversion relationship is called the torque distribution matrix C in the momentum wheel coordinate system. m0 (3×4 matrix).

[0009] Then the moment distribution matrix C in the satellite body coordinate system is m =A I C m0 (3×4 matrix).

[0010] When the main axis of the momentum wheel coordinate system and the main axis of the satellite are in the same direction, then A I Specifically:

[0011]

[0012] When the projections of the rotation directions of the oblique wheels in the momentum wheel coordinate system on the coordinate axis are all in the positive direction (i.e., the projections on the main axis direction are consistent with the main axis direction), the torque distribution matrix C in the satellite body coordinate system is m for:

[0013]

[0014] When the projections of the rotation directions of the oblique wheels in the momentum wheel coordinate system on the coordinate axis are all in the opposite direction (i.e., the projections in the main axis direction are opposite to the main axis direction), the torque distribution matrix C in the satellite body coordinate system is m for:

[0015]

[0016] (2) According to the moment distribution matrix C in the satellite body coordinate system m , get the speed n of each momentum wheel in the current state i , i = 1, 2, 3, 4, i = 1, 2, 3 represent the three active momentum wheels along the satellite's main axis x, y, and z axes respectively, and i = 4 represents the obliquely mounted wheel; and according to the moment of inertia I of each momentum wheel (the moment of inertia of the four momentum wheels is the same), the angular momentum h of each momentum wheel is obtained i =I·(n i ·30 / π).

[0017] (3) Determine the relationship Δh between all momentum wheels;

[0018] When the momentum wheel device is installed on the satellite, the coordinate axis directions of the momentum wheel coordinate system and the satellite body coordinate system are consistent, that is, the installation matrix Torque distribution matrix C in momentum wheel coordinate system m0 There are two cases where the projection of the oblique wheel's rotation direction on the coordinate axis is in the positive direction. Or in opposite directions, Corresponding to different torque distribution matrices, Δh is:

[0019]

[0020] (4) The momentum management torque of each momentum wheel is set to K1·Δh, K2·Δh, K3·Δh, and K4·Δh, respectively, where K1, K2, and K3 represent the momentum management torque coefficients of the active momentum wheel along the satellite's main axis x, y, and z, respectively, and K4 represents the momentum management torque coefficient of the tilted wheel;

[0021] (5) According to the momentum management torque of each momentum wheel and the torque distribution matrix C in the satellite body coordinate system m , the relationship between K1, K2, K3, and K4 is calculated using the following formula:

[0022]

[0023] (6) Take K1 = K (K ≥ 0, and the larger the K value, the faster the momentum wheel speed changes in the steady state), where K is a constant greater than or equal to 0. When K is greater than 0, the values ​​of K2, K3, and K4 are obtained according to the relationship between K1, K2, K3, and K4. Based on the target control torque T1, T2, T3, and T4 of each momentum wheel, the momentum management torque K1·Δh, K2·Δh, K3·Δh, and K4·Δh on each momentum wheel are added to or subtracted from the target control torque of each momentum wheel to obtain the control torque T1±K1·Δh, T2±K2·Δh, which should be applied to each momentum wheel. During T3±K3·Δh and T4±K4·Δh, the momentum wheel's rotational speed is effectively managed through the momentum management torque applied to each wheel, increasing or decreasing it to within a range of 50 to 100 rpm when the satellite is stable. When K=0, the momentum management torque is discontinued, and each wheel receives only the target control torque. Momentum management is performed to maintain the wheel's rotational speed within a range of 50 to 100 rpm when the satellite is stable. Based on the momentum management torque applied to each wheel, the wheel is allowed to reach any speed within this range. When momentum management is discontinued, the wheel's rotational speed remains constant, reducing its power consumption while ensuring sufficient torque output.

[0024] The beneficial effects of the present invention are:

[0025] The present invention provides a momentum management method for a micro-nano satellite momentum wheel. This method effectively controls the rotational speed and power consumption of the momentum wheel in a stable attitude state without affecting the normal torque output of the momentum wheel, ensuring sufficient torque output from the momentum wheel. The method is simple, reliable, and easy to implement. The speed of the momentum wheel rotational speed can be adjusted by adjusting the parameter K. The momentum wheel management method employed by the present invention can fully utilize the capacity of the momentum wheel without being affected by momentum wheel saturation. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the momentum wheel device structure.

[0027] Figure 2 This is a flow chart of a momentum management method for a micro-nano satellite momentum wheel according to the present invention.

[0028] Among them, a, b, and c are active measuring wheels along the satellite's main axes x, y, and z, d is the obliquely mounted momentum wheel, and e is the reaction wheel base. DETAILED DESCRIPTION

[0029] exist Figure 1 In the figure, the four momentum wheels a, b, c, and d are mounted on the reaction wheel base e. The moment of inertia of the four momentum wheels is I. During the satellite attitude control process, the four momentum wheels work simultaneously. Based on the installation of the momentum wheel device on the satellite, the torque distribution matrix C in the momentum wheel coordinate system can be obtained. m (3×4 matrix). According to the moment distribution matrix C m and the corresponding pseudo-inverse matrix C mk (4×3 matrix), which can convert the target control torque into the control torque of each momentum wheel. Due to the limitations of the momentum wheel, when the momentum wheel reaches a certain speed, the speed no longer increases, that is, the momentum wheel reaches saturation. With this type of momentum wheel device, due to momentum wheel saturation, after the satellite completes attitude control, the speed of the four momentum wheels may not be zero. This will affect the output of the momentum wheel device's control torque, and because the momentum wheel continuously rotates, the power consumption of the momentum wheel will increase. To avoid this situation, a momentum management method has been designed for this type of momentum wheel. This momentum management method can effectively reduce the momentum wheel's speed without affecting the output of the control torque, ensuring sufficient control capability of the momentum wheel and reducing power consumption.

[0030] Depend on Figure 2 The momentum management flow chart shows the steps for momentum management of the momentum wheel in a stable attitude state:

[0031] (1) According to the installation of the four momentum wheels of the momentum wheel device on the satellite, the torque distribution matrix C in the satellite body coordinate system is obtained: m ;

[0032] (2) According to the moment distribution matrix C in the satellite body coordinate system m , get the speed n of each momentum wheel in the current state i , i = 1, 2, 3, 4, i = 1, 2, 3 represent the three active momentum wheels along the satellite's main axis x, y, and z axes respectively, and i = 4 represents the obliquely mounted wheel; and according to the moment of inertia I of each momentum wheel, the angular momentum h of each momentum wheel is obtained i =I·(n i ·30 / π);

[0033] (3) Determine the relationship Δh between all momentum wheels;

[0034] (4) The momentum management torque of each momentum wheel is set to K1·Δh, K2·Δh, K3·Δh, and K4·Δh, respectively, where K1, K2, and K3 represent the momentum management torque coefficients of the active momentum wheel along the satellite's main axis x, y, and z, respectively, and K4 represents the momentum management torque coefficient of the tilted wheel;

[0035] (5) According to the momentum management torque of each momentum wheel and the torque distribution matrix C in the satellite body coordinate system m , the relationship between K1, K2, K3, and K4 is calculated using the following formula:

[0036]

[0037] (6) Take K1 = K, where K is a constant greater than or equal to 0, and obtain the values ​​of K2, K3, and K4 according to the relationship between K1, K2, K3, and K4, and at the same time obtain the target control torque T1, T2, T3, and T4 of each momentum wheel; when K is greater than 0, add or subtract the momentum management torque K1·Δh, K2·Δh, K3·Δh, and K4·Δh on each momentum wheel to the target control torque of each momentum wheel to obtain the torque that should be applied to each momentum wheel. The control torque T1±K1·Δh, T2±K2·Δh, T3±K3·Δh, T4±K4·Δh is used to effectively manage the rotation speed of the momentum wheel through the momentum management torque of each momentum wheel, so that the rotation speed of the momentum wheel increases or decreases within the range of 50 to 100 rpm when the satellite is in a stable state; when K=0, when the momentum management torque is stopped, the momentum wheel rotation speed will be maintained in the range of 50 to 100 rpm when the satellite is in a stable state.

[0038] In step (1), when the rotation direction of the momentum wheel on the main axis of the momentum wheel device is consistent with the main axis direction of the satellite, and the component of the rotation direction of the oblique wheel in the main axis direction is consistent with the main axis direction, it is possible to

[0039] Determine the torque distribution matrix C in the satellite body coordinate system m0 for:

[0040]

[0041] In step (3), the relationship between all momentum wheels is

[0042] In step (5), the relationship between K1, K2, K3, and K4 is:

[0043] In step (6), when K1=K, the momentum management torque on each momentum wheel is K·Δh, K·Δh,

[0044] The target control torque of each momentum wheel is added to or subtracted from the momentum management torque K1·Δh, K2·Δh, K3·Δh, K4·Δh on each momentum wheel to obtain the control torque T1±K·Δh, T2±K·Δh, T3±K·Δh that should be applied to each momentum wheel. Assign a value to K. When K is greater than 0, the momentum management torque of each momentum wheel is used to effectively manage the rotation speed of the momentum wheel, so that the rotation speed increases or decreases within the range of 50 to 100 rpm when the satellite is in a stable state. When K = 0, the momentum management torque is stopped from being applied to the momentum wheel, and each momentum wheel only has the target control torque, so that its rotation speed is maintained within the range of 50 to 100 rpm when the satellite is in a stable state.

Claims

1. A momentum management method for a micro-nano satellite momentum wheel, used for managing the momentum of the momentum wheel in a stable attitude state, characterized in that: The following steps are involved: (1) According to the installation of the four momentum wheels of the momentum wheel device on the satellite, the torque distribution matrix C in the satellite body coordinate system is obtained: m ; (2) According to the moment distribution matrix C in the satellite body coordinate system m , get the speed n of each momentum wheel in the current state i , i = 1, 2, 3, 4, i = 1, 2, 3 represent the three active momentum wheels along the satellite's main axis x, y, and z axes respectively, and i = 4 represents the obliquely mounted wheel; and according to the moment of inertia I of each momentum wheel, the angular momentum h of each momentum wheel is obtained i =I·(n i ·30 / π); (3) Determine the relationship Δh between all momentum wheels; (4) The momentum management torque of each momentum wheel is set to K1·Δh, K2·Δh, K3·Δh, and K4·Δh, respectively, where K1, K2, and K3 represent the momentum management torque coefficients of the active momentum wheel along the satellite's main axis x, y, and z, respectively, and K4 represents the momentum management torque coefficient of the tilted wheel; (5) According to the momentum management torque of each momentum wheel and the torque distribution matrix C in the satellite body coordinate system m , the relationship between K1, K2, K3, and K4 is calculated using the following formula: (6) Take K1 = K, where K is a constant greater than or equal to 0. According to the relationship between K1, K2, K3, and K4, the values ​​of K2, K3, and K4 are obtained, and the target control torques T1, T2, T3, and T4 of each momentum wheel are obtained at the same time. The target control torque of each momentum wheel is added to or subtracted from the momentum management torque K1·Δh, K2·Δh, K3·Δh, and K4·Δh on each momentum wheel to obtain the control torque T1±K1·Δh, T2±K2·Δh, T3±K3·Δh, and T4±K4·Δh that should be applied to each momentum wheel. Based on the momentum management torque of each momentum wheel, the rotation speed of the momentum wheel can be reduced or increased when the satellite is in a stable state.

2. The momentum management method for a micro-nano satellite momentum wheel according to claim 1, characterized in that: In step (1), the moment distribution matrix C m The calculation method is: C m =A I C m0 Among them, A I is the installation matrix, C m0 is the torque distribution matrix in the momentum wheel coordinate system.

3. The momentum management method for a micro-nano satellite momentum wheel according to claim 2, characterized in that: When the momentum wheel device is installed on the satellite, the coordinate axis direction of the momentum wheel coordinate system is consistent with that of the satellite body coordinate system, and the installation matrix Torque distribution matrix C in momentum wheel coordinate system m0 There are two cases: when the projection of the rotating direction of the oblique wheel on the coordinate axis is in the positive direction, When the projections of the rotating directions of the obliquely mounted wheels on the coordinate axis are in opposite directions, 4. The momentum management method for a micro-nano satellite momentum wheel according to claim 3, characterized in that: In step (3), the relationship Δh between all momentum wheels includes two cases, specifically: When the projection of the rotating direction of the tilted wheel on the main axis is consistent with the main axis direction, Δh is specifically: When the projections of the rotating directions of the obliquely mounted wheels on the coordinate axis are in opposite directions, Δh is specifically:

5. The momentum management method for a micro-nano satellite momentum wheel according to claim 1, characterized in that: In step (6), the momentum of the momentum wheel is managed by adding or canceling the momentum management torque, so that the momentum wheel speed is maintained in the range of 50 to 100 rpm; when K>0, the momentum management torque is applied to the momentum wheel, so that the momentum wheel speed is increased or decreased to 50 to 100 rpm under the stable state of the satellite; When K=0, the momentum management torque is stopped from being applied to the momentum wheel. Each momentum wheel only has the target control torque, and the momentum wheel speed is maintained at a constant value between 50 and 100 rpm when the satellite is in a stable state.

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