Reaction flywheel set maximum energy efficiency control method and satellite attitude control system

Abstract

The invention relates to a maximum energy efficiency control method for a reaction flywheel set and a satellite attitude control system. The method comprises the following steps: providing a satellite attitude control system provided with a reaction flywheel group; a saturation protection threshold and a reaction flywheel rotation speed upper limit of the reaction flywheel rotation speed are set, the saturation protection threshold is smaller than the reaction flywheel rotation speed upper limit, and the saturation protection threshold is used for limiting the actual rotation speed of the reaction flywheel before the reaction flywheel reaches the reaction flywheel rotation speed upper limit; therefore, the time that the rotating speed of the reaction flywheel set reaches the upper limit of the rotating speed of the reaction flywheel is prolonged. According to the method, the time for the rotating speed of the reaction flywheels to reach the upper limit can be prolonged to the maximum extent, the angular momentum, needing to be compensated, of the reaction flywheels is more fully distributed to each reaction flywheel, the angular momentum compensation capacity of the reaction flywheels is fully played as much as possible, and the maximum angular momentum capable of being provided by the reaction flywheels is fully played.

Description

Technical Field

[0001] The present invention relates to the technical field of satellite attitude control, and specifically provides a maximum energy efficiency control method for a reaction flywheel group and a satellite attitude control system. Background Art

[0002] In modern aerospace, satellite attitude control is crucial, directly impacting mission effectiveness and operational safety. Reaction flywheels, as core components of satellite attitude control systems, are widely used on various satellites due to their high precision, high reliability, and ability to rapidly respond to attitude adjustments. Reaction flywheels are crucial for satellite attitude adjustment. Currently, satellite attitude control using reaction flywheels relies primarily on the principle of conservation of angular momentum. Specifically, reaction flywheel speeds have an upper limit. Therefore, when a reaction flywheel reaches its upper limit, the speed is stabilized at that limit, and the control torque is distributed to the remaining flywheels, continuing the control until the speed of the n-2th reaction flywheel also reaches the upper limit (n is the number of reaction flywheels on the satellite), achieving reaction flywheel-based attitude control. However, the reaction flywheel speed can easily reach its upper limit. Once multiple flywheels reach saturation, satellite attitude control accuracy decreases, resulting in suboptimal attitude control. Therefore, it is crucial to solve the dilemma of reaction flywheel control in existing satellite attitude control and improve the overall efficiency of satellite attitude control. Summary of the Invention

[0003] To address at least some of the aforementioned issues in the prior art, the present invention provides a method for maximizing the energy efficiency of a reaction flywheel assembly and a satellite attitude control system. This method achieves maximum energy efficiency control of the reaction flywheel assembly through an excess angular momentum compensation control strategy. Specifically, a saturation protection threshold for the reaction flywheel speed is set in the satellite attitude control system (control actuator system) for n reaction flywheels. After the actual speeds of n-2 reaction flywheels reach the saturation protection threshold, the actual speeds of these n-2 reaction flywheels are alternately increased until they reach the upper speed limit. This ensures that each reaction flywheel can fully function and minimizes the time it takes for the reaction flywheel speed to reach the upper speed limit, thereby enhancing the maximum control capability of the reaction flywheels and achieving maximum energy efficiency control of the reaction flywheel assembly.

[0004] A first aspect of the present invention provides a method for controlling a reaction flywheel assembly to maximize energy efficiency, the method comprising: Provide satellite attitude control systems equipped with reaction flywheel assemblies; and A saturation protection threshold and an upper limit of the reaction flywheel speed are set. The saturation protection threshold is smaller than the upper limit of the reaction flywheel speed. The saturation protection threshold is used to limit the actual speed of the reaction flywheel before it reaches the upper limit of the reaction flywheel speed, thereby extending the time for the speed of the reaction flywheel group to reach the upper limit of the reaction flywheel speed.

[0005] Furthermore, the reaction flywheel group includes n reaction flywheels, wherein n is a natural number greater than 2; and the satellite attitude control system adopts the reaction flywheel group to realize satellite attitude control.

[0006] Furthermore, the saturation protection threshold is set based on the flywheel's performance parameters and the requirements of satellite attitude control. The reaction flywheel's speed saturation protection threshold is generally slightly lower than the reaction flywheel's speed upper limit. Thus, the maximum energy efficiency control method for the reaction flywheel assembly proposed in the present invention can be employed between the saturation protection threshold and the speed upper limit.

[0007] Furthermore, the extension includes: when the actual rotational speeds of the n-2 reaction flywheels all reach the saturation protection threshold, the actual rotational speeds of the n-2 reaction flywheels are alternately increased to reach the upper limit of the reaction flywheel rotational speed, so as to give full play to the angular momentum compensation capability of the reaction flywheel group and enhance the maximum control capability of the reaction flywheel group.

[0008] Furthermore, setting the saturation protection threshold of the reaction flywheel speed and the upper limit of the reaction flywheel speed includes the following steps: When the actual speed of one reaction flywheel reaches the saturation protection threshold, the actual speed of the reaction flywheel is restricted from further increasing; at this time, the excess torque required to be provided by the reaction flywheel is provided by the other n-1 reaction flywheels, that is, the excess angular momentum is distributed to the other reaction flywheels, ensuring that each reaction flywheel can fully play its role, extending the time for the reaction flywheel speed to reach the upper limit as much as possible, making full use of the angular momentum compensation capability of the reaction flywheel, and improving the overall control effect; When the actual speed of the second reaction flywheel reaches the saturation protection threshold, the actual speed of the reaction flywheel is restricted from further increasing; The process continues in this way until the actual rotational speed of the n-2 reaction flywheel reaches the saturation protection threshold. At this time, the n-2 reaction flywheels enter a stage of alternating increase in actual rotational speed, so that the actual rotational speed of the n-2 reaction flywheel reaches the upper limit of the reaction flywheel rotational speed.

[0009] Furthermore, in the stage where the actual rotation speeds are alternately increased, the step of alternately increasing the actual rotation speeds of the n-2 reaction flywheels includes: When the actual speed of one of the reaction flywheels is the maximum, the actual speed of the reaction flywheel stops increasing; Relying on the other reaction flywheels to perform attitude control until the actual speed of one of the other reaction flywheels exceeds the speed of the reaction flywheel with the highest actual speed in step S1; Repeat the above steps until the actual rotation speeds of the n-2 reaction flywheels all reach the upper limit of the reaction flywheel rotation speed.

[0010] Furthermore, the theoretical rotation speed is calculated in real time by any one of a PID control algorithm, an LQR control algorithm, an adaptive control algorithm or a robust control algorithm.

[0011] Furthermore, the arrangement of the reaction flywheel group includes any one of a four-slant arrangement, an orthogonal three-axis arrangement or a redundant six-wheel arrangement.

[0012] Furthermore, the satellite attitude control system includes a measurement component, a control component, and an actuator component. Common measurement components include gyroscopes, accelerometers, magnetometers, and star sensors. When a satellite is performing an Earth observation mission, the measurement component monitors the satellite's attitude in real time and promptly feeds data back to the control component if any attitude deviation occurs. The control component includes a satellite control computer, which receives attitude data from the measurement component and processes it according to a preset control algorithm (such as a PID control algorithm) to generate control instructions. The actuator component, based on the instructions issued by the control component, generates corresponding actions to adjust the satellite's attitude. Common actuator components include reaction flywheels, jet thrusters, and magnetic torquers. The magnetic torquer is primarily used to offload the impact of angular momentum perturbations introduced by the long-term space environment on the reaction flywheel's rotational speed. The satellite attitude control system also includes jet thrusters, which are primarily used for orbital control of the satellite and do not operate in conjunction with the reaction flywheel.

[0013] Furthermore, the satellite attitude control system includes a satellite control computer. The satellite control computer receives attitude data, performs calculations, generates control instructions, and controls the actual speed of the reaction flywheel. The satellite control computer is a computer commonly used in existing spacecraft.

[0014] Furthermore, during attitude control, the actual speed is accelerated or decelerated according to the theoretical speed. The theoretical speed is calculated in real time by the satellite control computer, which then accelerates or decelerates the actual speed according to the theoretical speed. The satellite control computer controls the rotation of the flywheel motor, thereby controlling the flywheel's speed. The actual speed is the actual rotational speed of the reaction flywheel, which directly affects the angular momentum generated by the reaction flywheel and the effectiveness of satellite attitude control.

[0015] A second aspect of the present invention provides a satellite attitude control system, comprising: a reaction flywheel assembly, configured to provide a reaction torque for satellite attitude control, wherein the reaction flywheel assembly comprises n reaction flywheels; and The satellite service computer is configured to execute the steps of the reaction flywheel group maximum energy efficiency control method as described in the first aspect to achieve control of the satellite attitude.

[0016] During the actual control process, as the speeds of multiple flywheels successively reach their upper limits, the accuracy of satellite attitude control decreases, making it impossible to accurately meet mission requirements, affecting the effectiveness of the satellite in performing observation, communication, and other tasks, and limiting the satellite's application in complex mission scenarios. The maximum energy efficiency control method for a reaction flywheel assembly provided by the present invention sets a reaction flywheel saturation protection threshold based on the flywheel angular momentum distribution principle (different satellites use different reaction flywheels, so the upper speed limits of the reaction flywheels also vary. Since the saturation protection threshold must be slightly lower than the reaction flywheel speed limit to implement the present method, the saturation protection thresholds of different satellites will also vary). When a reaction flywheel with an actual speed reaching the saturation protection threshold appears, no angular momentum is allocated, and the angular momentum that needs to be compensated is allocated to other flywheels. This process continues until only two reaction flywheels have actual speeds that have not reached the saturation protection threshold. At this time, the actual speeds of the reaction flywheels that have reached the saturation protection threshold are alternately increased until the reaction flywheel speed limit is reached.

[0017] The present invention has at least the following beneficial effects: the maximum energy efficiency control method of the reaction flywheel group of the invention can extend the time for the reaction flywheel speed to reach the upper limit to the greatest extent, and distribute the angular momentum that the reaction flywheel needs to compensate more fully to each reaction flywheel, so as to give full play to the angular momentum compensation ability of the reaction flywheel as much as possible, give full play to the maximum angular momentum that the reaction flywheel can provide, and then give full play to the maximum control ability of the reaction flywheel, thereby realizing maximum energy efficiency control of the reaction flywheel group. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] To further illustrate the above and other advantages and features of various embodiments of the present invention, a more detailed description of various embodiments of the present invention will be presented with reference to the accompanying drawings. It will be understood that these drawings depict only typical embodiments of the present invention and are not to be considered as limiting the scope thereof. In the drawings, for clarity, identical or corresponding parts will be represented by the same or similar reference numerals.

[0019] Figure 1 A schematic diagram showing the change in actual rotational speed of the reaction flywheel assembly over time during satellite attitude control of the reaction flywheel assembly in Example 1 of the present invention is shown; Figure 2 A schematic diagram showing the change in actual rotational speed of the reaction flywheel assembly over time during satellite attitude control of the reaction flywheel assembly in Example 2 of the present invention is shown; Reference numerals: FwA—actual speed curve of reaction flywheel A, FwB—actual speed curve of reaction flywheel B, FwC—actual speed curve of reaction flywheel C, FwD—actual speed curve of reaction flywheel D. DETAILED DESCRIPTION

[0020] It should be noted that components in the drawings may be shown exaggerated for illustrative purposes and are not necessarily true to scale.

[0021] In the present invention, each embodiment is only intended to illustrate the aspects of the present invention and should not be construed as limiting.

[0022] In the present invention, unless otherwise specified, the quantifiers "a" and "an" do not exclude the presence of multiple elements.

[0023] It should also be pointed out that in the embodiments of the present invention, for the sake of clarity and simplicity, only a portion of the parts or components may be shown, but a person skilled in the art will understand that under the teachings of the present invention, the required parts or components may be added according to the needs of the specific scenario.

[0024] It should also be pointed out that within the scope of the present invention, the terms "same", "equal", "equal to" and the like do not mean that the two values ​​are absolutely equal, but allow a certain reasonable error, that is, the terms also cover "substantially the same", "substantially equal", and "substantially equal to".

[0025] It should also be noted that in the description of the present invention, the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate description and simplify the present invention. They do not explicitly or implicitly state that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] In addition, the embodiments of the present invention describe the process steps in a specific order. However, this is only for the convenience of distinguishing the steps and does not limit the order of the steps. In different embodiments of the present invention, the order of the steps can be adjusted according to the process. In addition, the step numbers are only for the purpose of referring to specific steps and do not limit the order in which the steps are performed.

[0027] The arrangement of the reaction flywheel assembly in the following embodiments adopts a four-oblique arrangement.

[0028] Example 1 This embodiment provides a method for controlling the maximum energy efficiency of a reaction flywheel assembly. The method is applied to a satellite attitude control system equipped with four reaction flywheels (FwA, FwB, FwC, and FwD). This method sets the saturation protection threshold of the reaction flywheel speed to 2500 r / min and the upper limit of the reaction flywheel speed to 3490 r / min, thereby enabling the reaction flywheel assembly to perform attitude control on the satellite.

[0029] Assume that a satellite equipped with a reaction flywheel group performs reaction flywheel PID control with an initial angular velocity of [2.00 2.00 0.47]° / s, and the target angular velocity is [0 0 0]° / s, and the satellite angular velocity modulus is controlled to decrease. Figure 1 A schematic diagram shows the time-varying actual speed of the reaction flywheel assembly during satellite attitude control in this embodiment. It can be seen that at 85 seconds of control time, the actual speed of reaction flywheel A reaches the saturation protection threshold of 2500 r / min. Thereafter, reaction flywheel A maintains this speed, while satellite attitude control is performed by the other three flywheels. At 150 seconds of control time, the actual speed of reaction flywheel B also reaches the saturation protection threshold of 2500 r / min. Thereafter, reaction flywheels A and B begin alternating to increase their actual speeds until both reach the upper limit of 3490 r / min at 220 seconds. During this process, the satellite's angular velocity ultimately drops to [0.42 0.30 0.47]° / s, with the angular velocity modulus decreasing by 2.17° / s.

[0030] After attitude control, the angular velocity is significantly reduced, indicating that the satellite attitude changes greatly and the satellite attitude control adjustment effect of the reaction wheel group is obvious.

[0031] Example 2 This embodiment differs from Embodiment 1 only in that a saturation protection threshold for the reaction flywheel speed is set; all other conditions are the same as those in Embodiment 1. Specifically, it is assumed that a satellite equipped with a reaction flywheel assembly is subjected to reaction flywheel PID control with an initial angular velocity of [2.00 2.000.47]° / s, a target angular velocity of [0 0 0]° / s, and the satellite angular velocity modulus is controlled to decrease. No saturation protection threshold for the reaction flywheel speed is set.

[0032] Figure 2A schematic diagram shows the change in the actual speed of the reaction flywheel group over time during the satellite attitude control process of the reaction flywheel group in this embodiment. It can be seen that the actual speed of reaction flywheel A reaches the upper limit of the reaction flywheel speed of 3490 r / min when the satellite control time is 125 seconds. The actual speed of reaction flywheel A then maintains this speed. Satellite attitude control is performed by the other three reaction flywheels. At the control time of 190 seconds, the actual speed of reaction flywheel B also reaches the upper limit of the reaction flywheel speed of 3490 r / min. During this process, the angular velocity of the satellite finally drops to [0.37 0.38 0.54]° / s, and the angular velocity modulus drops by 2.11° / s. This embodiment does not fully utilize the maximum angular momentum that the reaction flywheel can provide, and thus does not fully utilize the maximum control capability of the reaction flywheel.

[0033] By comparing the above-mentioned Example 1 and Example 2, it can be seen that the degree of angular velocity reduction in Example 1 is greater than that in Example 2, that is, the degree of angular velocity reduction in the method of setting the saturation protection threshold of the reaction flywheel speed is greater than that in the method of not setting the reaction flywheel saturation protection threshold. This shows that after setting the saturation protection threshold, the reaction flywheel can reasonably distribute angular momentum and avoid premature saturation, so that each reaction flywheel can participate in attitude control for a longer time, more fully compensate for angular momentum, and thus further reduce the satellite angular velocity.

[0034] Therefore, by adopting the maximum energy efficiency control method of the reaction flywheel group in the present invention, the reaction wheel group can more effectively utilize its own angular momentum changes, provide a more appropriate reaction torque for the satellite, and maximize the angular momentum compensation capability of the flywheel.

[0035] Although certain embodiments of the present invention have been described in this application, those skilled in the art will appreciate that these embodiments are provided by way of example only. Numerous variations, alternatives, and modifications will be contemplated by those skilled in the art in light of the teachings of this disclosure without departing from the scope of the present invention. The appended claims are intended to define the scope of the present invention and are intended to encompass methods and structures within the scope of these claims and their equivalents.

Claims

1. A maximum energy efficiency control method for a reaction flywheel group, characterized in that: The method includes: A satellite attitude control system is provided, wherein the reaction flywheel assembly includes n reaction flywheels, wherein n is a natural number greater than 2; and A saturation protection threshold and an upper limit of the reaction flywheel speed are set, wherein the saturation protection threshold is smaller than the upper limit of the reaction flywheel speed. The saturation protection threshold is used to limit the actual speed of the reaction flywheel before it reaches the upper limit of the reaction flywheel speed, thereby extending the time for the speed of the reaction flywheel group to reach the upper limit of the reaction flywheel speed: when the actual speeds of the n-2 reaction flywheels all reach the saturation protection threshold, the actual speeds of the n-2 reaction flywheels are alternately increased to reach the upper limit of the reaction flywheel speed.

2. The maximum energy efficiency control method of a reaction flywheel assembly according to claim 1, characterized in that: Setting the saturation protection threshold and the upper limit of the reaction flywheel speed includes the following steps: When the actual speed of a reaction flywheel reaches the saturation protection threshold, the actual speed of the reaction flywheel is restricted from further increasing; When the actual speed of the second reaction flywheel reaches the saturation protection threshold, the actual speed of the reaction flywheel is restricted from further increasing; The process continues in this way until the actual rotational speed of the n-2 reaction flywheel reaches the saturation protection threshold. At this time, the n-2 reaction flywheels enter a stage of alternating increase in actual rotational speed, so that the actual rotational speed of the n-2 reaction flywheel reaches the upper limit of the reaction flywheel rotational speed.

3. The maximum energy efficiency control method of a reaction flywheel assembly according to claim 2, characterized in that: In the stage of alternating increase in the actual rotational speed, the step of alternating increase in the actual rotational speed of the n-2 reaction flywheels comprises: When the actual speed of one of the reaction flywheels is the maximum, the actual speed of the reaction flywheel stops increasing; Relying on the other reaction flywheels to perform attitude control until the actual speed of one of the other reaction flywheels exceeds the speed of the reaction flywheel with the highest actual speed in step S1; Repeat the above steps until the actual rotation speeds of the n-2 reaction flywheels all reach the upper limit of the reaction flywheel rotation speed.

4. The maximum energy efficiency control method of a reaction flywheel assembly according to claim 2, characterized in that: The theoretical rotation speed is calculated in real time by any one of a PID control algorithm, an LQR control algorithm, an adaptive control algorithm or a robust control algorithm.

5. The maximum energy efficiency control method of a reaction flywheel assembly according to claim 2, characterized in that: The arrangement of the reaction flywheel group includes any one of a four-slant arrangement, an orthogonal three-axis arrangement or a redundant six-wheel arrangement.

6. The maximum energy efficiency control method of a reaction flywheel assembly according to claim 2, characterized in that: The satellite attitude control system includes a satellite computer.

7. The maximum energy efficiency control method of a reaction flywheel assembly according to claim 2, characterized in that: When performing attitude control, the actual rotation speed is accelerated or decelerated according to the theoretical rotation speed. The theoretical rotation speed is calculated in real time by the satellite service computer, and the actual rotation speed is accelerated or decelerated according to the theoretical rotation speed.

8. A satellite attitude control system, characterized in that: include: A reaction flywheel assembly, used to provide a reaction torque for satellite attitude control, wherein the reaction flywheel assembly includes n reaction flywheels; as well as A satellite service computer is configured to execute the steps of the reaction flywheel group maximum energy efficiency control method as described in any one of claims 1 to 7 to achieve control of the satellite attitude.

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