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

Abstract

The present application relates to a kind of maximum energy efficiency control method of reaction flywheel group and satellite attitude control system.The method includes providing satellite attitude control system equipped with reaction flywheel group;Reaction flywheel speed saturation protection threshold and reaction flywheel speed upper limit are set, the saturation protection threshold is less than the reaction flywheel speed upper limit, the saturation protection threshold is used to limit the actual speed of reaction flywheel before reaching the reaction flywheel speed upper limit, to extend the time of reaction flywheel group speed to reach the reaction flywheel speed upper limit.The method of the present application can extend the time of reaction flywheel speed to reach upper limit to the maximum, the angular momentum that reaction flywheel needs to compensate is more fully distributed to each reaction flywheel, the angular momentum compensation capacity of reaction flywheel is exerted as far as possible, the maximum angular momentum that reaction flywheel can provide is fully exerted.

Description

TECHNICAL FIELD

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

[0002] In the modern aerospace field, satellite attitude control is crucial, which is directly related to the mission execution effect and operation safety of the satellite. As the core component of the satellite attitude control system, the reaction flywheel is widely used in various satellites due to its high precision, high reliability, and the ability to quickly respond to attitude adjustment requirements. The reaction flywheel is an important attitude adjustment component of the satellite. Currently, when the reaction flywheel is used for satellite attitude control, the control is mainly based on the principle of angular momentum conservation. Specifically, the rotation speed of the reaction flywheel has an upper limit, so when the reaction flywheel control is performed, when the rotation speed of a certain reaction flywheel reaches the upper limit, the rotation speed of the flywheel is stabilized at the upper limit, and the wheel control torque is distributed to other flywheels to continue wheel control, and the rotation speed of the n-2th reaction flywheel is also reached (n is the number of reaction flywheels configured for the satellite). The upper limit to achieve satellite attitude control of the reaction flywheel. However, the rotation speed of the reaction flywheel is easy to reach the upper limit, and once the rotation speed of multiple flywheels is saturated in succession, it will lead to a decrease in the accuracy of satellite attitude control and poor satellite attitude control effect. Therefore, it is important to solve the problem of reaction flywheel control in existing satellite attitude control and improve the overall efficiency of satellite attitude control. SUMMARY

[0003] To solve at least part of the above problems in the prior art, the present application provides a maximum energy efficiency control method for a reaction flywheel group and a satellite attitude control system. The method realizes maximum energy efficiency control of the reaction flywheel group through a redundant angular momentum compensation control strategy. Specifically, a saturation protection threshold for the rotation speed of the reaction flywheel is set in the satellite attitude control system (control execution mechanism system) of the n reaction flywheels, and after the actual rotation speed of the n-2 reaction flywheels reaches the saturation protection threshold, the actual rotation speed of the n-2 reaction flywheels is alternately increased until the rotation speed of the reaction flywheel reaches the upper limit, so that each reaction flywheel can fully play its role and the time for the rotation speed of the reaction flywheel to reach the upper limit is as long as possible, thereby enhancing the maximum control ability of the reaction flywheel and realizing maximum energy efficiency control of the reaction flywheel group.

[0004] The first aspect of the present application provides a maximum energy efficiency control method for a reaction flywheel group, which comprises:

[0005] providing a satellite attitude control system equipped with a reaction flywheel group; and

[0006] A saturation protection threshold of the reaction flywheel speed and an upper limit of the reaction flywheel speed are set, the saturation protection threshold is less than the upper limit of the reaction flywheel speed, and the saturation protection threshold is used to limit the actual speed of the reaction flywheel before the reaction flywheel reaches the upper limit of the reaction flywheel speed, so as to prolong the time for the reaction flywheel group speed to reach the upper limit of the reaction flywheel speed.

[0007] Further, the reaction flywheel group includes n reaction flywheels, where n is a natural number greater than 2; and the satellite attitude control system uses the reaction flywheel group to realize satellite attitude control.

[0008] Further, the saturation protection threshold is set according to the performance parameters of the flywheel and the demand of satellite attitude control. The saturation protection threshold of the reaction flywheel speed is generally slightly lower than the upper limit of the reaction flywheel speed, and then the maximum energy efficiency control method of the reaction flywheel group proposed in the application can be used between the saturation protection threshold and the upper limit of the speed.

[0009] Further, the prolonging includes: when the actual speeds of 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, so as to fully exert the angular momentum compensation capacity of the reaction flywheel group and enhance the maximum control capacity of the reaction flywheel group.

[0010] Further, setting the saturation protection threshold of the reaction flywheel speed and the upper limit of the reaction flywheel speed includes the following steps:

[0011] When the actual speed of one reaction flywheel reaches the saturation protection threshold, the actual speed of the reaction flywheel is limited to continue to increase; at this time, the excess torque required to be provided by the reaction flywheel is provided by other n-1 reaction flywheels, that is, the excess angular momentum is distributed to other reaction flywheels, so as to ensure that each reaction flywheel can fully exert its function, prolong the time for the reaction flywheel speed to reach the upper limit as much as possible, fully utilize the angular momentum compensation capacity of the reaction flywheel, and improve the overall control effect;

[0012] When the actual speed of the second reaction flywheel reaches the saturation protection threshold, the actual speed of the reaction flywheel is limited to continue to increase;

[0013] By analogy, until the actual speed of the n-2 reaction flywheel reaches the saturation protection threshold, at this time, the n-2 reaction flywheels enter the actual speed alternately increasing stage, so as to make the actual speeds of the n-2 reaction flywheels reach the upper limit of the reaction flywheel speed.

[0014] Further, in the actual speed alternately increasing stage, the step of alternately increasing the actual speeds of the n-2 reaction flywheels includes:

[0015] the actual rotation speed of one of the reaction flywheels stops increasing when the actual rotation speed of the reaction flywheel reaches the maximum;

[0016] controlling the attitude by means of the other reaction flywheels until the actual rotation speed of one of the other reaction flywheels exceeds the rotation speed of the reaction flywheel with the maximum actual rotation speed in step S1;

[0017] repeating the above steps until the actual rotation speeds of the n-2 reaction flywheels all reach the upper limit of the rotation speed of the reaction flywheels.

[0018] Further, 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.

[0019] Further, the arrangement of the reaction flywheel group includes any one of four oblique arrangements, orthogonal three-axis arrangement or redundant six-wheel arrangement.

[0020] Further, the satellite attitude control system includes a measurement component, a control component and an execution component. Common measurement components include gyroscopes, accelerometers, magnetometers, star sensors, etc. When the satellite is performing an earth observation task, the measurement component monitors the satellite attitude in real time, and if the attitude deviates, the data is fed back to the control component in time. The control component includes a satellite computer, which receives the attitude data from the measurement component, performs operation and processing according to a preset control algorithm (such as a PID control algorithm), and generates a control instruction. The execution component produces corresponding actions according to the instruction from the control component to adjust the satellite attitude. Common execution components include reaction flywheels, jet thrusters and magnetic torque devices. The magnetic torque device is mainly used to unload the influence of the long-term angular momentum perturbation introduced by the space environment on the rotation speed of the reaction flywheel. The satellite attitude control system also includes a jet thruster, which is mainly used for orbit control operation of the satellite and has no cooperative working relationship with the reaction flywheel.

[0021] Further, the satellite attitude control system includes a satellite computer. The satellite computer receives attitude data and performs operation and processing to generate a control instruction and control the actual rotation speed of the reaction flywheel. The satellite computer is a computer product commonly used in existing spacecraft.

[0022] Further, in the process of attitude control, the actual rotation speed is accelerated or decelerated according to the theoretical rotation speed calculated by the on-board computer in real time, and the actual rotation speed is accelerated or decelerated according to the theoretical rotation speed. The on-board computer controls the rotation of the flywheel motor, and in turn controls the rotation speed of the flywheel. The actual rotation speed is the real rotation speed of the reaction flywheel, which directly affects the angular momentum generated by the reaction flywheel and the control effect on the satellite attitude.

[0023] The second aspect of the application provides a satellite attitude control system, comprising:

[0024] a reaction flywheel group for providing reaction torque for satellite attitude control, the reaction flywheel group comprising n reaction flywheels; and

[0025] an on-board computer configured to perform the steps of the reaction flywheel group maximum energy efficiency control method according to the first aspect to achieve control of the satellite attitude.

[0026] In the actual control process, as the rotation speeds of multiple flywheels reach the upper limit successively, the satellite attitude control accuracy decreases, which cannot accurately meet the task requirements, affects the effect of satellite observation, communication and other tasks, and limits the application of the satellite in complex task scenarios. The reaction flywheel group maximum energy efficiency control method provided by the application sets a saturation protection threshold based on the flywheel angular momentum distribution principle (the upper limit of the rotation speed of the reaction flywheel is different for different satellites due to the selection of the reaction flywheel, and the saturation protection threshold is slightly lower than the upper limit of the rotation speed of the reaction flywheel to implement the method, so the saturation protection threshold is also different for different satellites), when the actual rotation speed of the reaction flywheel reaches the saturation protection threshold, no angular momentum is distributed, the angular momentum that needs to be compensated is distributed to other flywheels, until only two reaction flywheels have actual rotation speeds that do not reach the saturation protection threshold, the actual rotation speeds of the reaction flywheels that reach the saturation protection threshold are alternately increased until the upper limit of the rotation speed of the reaction flywheel is reached.

[0027] The reaction flywheel group maximum energy efficiency control method of the application can maximize the time for the rotation speed of the reaction flywheel to reach the upper limit, more fully distribute the angular momentum that needs to be compensated by the reaction flywheel to each reaction flywheel, maximize the angular momentum compensation capacity of the reaction flywheel, maximize the maximum angular momentum that can be provided by the reaction flywheel, and in turn maximize the maximum control capacity of the reaction flywheel, thereby achieving maximum energy efficiency control of the reaction flywheel group. BRIEF DESCRIPTION OF DRAWINGS

[0028] To further clarify the above and other advantages and features of the present embodiments, a more particular description of embodiments of the application will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the application and are therefore not to be considered limiting of its scope. The drawings incorporate graphics for purposes of clarity that are not necessarily drawn to scale.

[0029] Figure 1 A diagram showing the actual speed of the reaction flywheel group over time during the satellite attitude control process of the reaction flywheel group in Embodiment 1 of the application is shown;

[0030] Figure 2 A diagram showing the actual speed of the reaction flywheel group over time during the satellite attitude control process of the reaction flywheel group in Embodiment 2 of the application is shown;

[0031] Legend: 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

[0032] It should be noted that the components in the various drawings can be shown exaggeratedly for illustration purposes, and are not necessarily to scale.

[0033] In the present application, each embodiment is merely intended to illustrate the scheme of the present application, and should not be understood as limiting.

[0034] In the present application, unless specifically indicated, the quantifier "one", "a" does not exclude the scenario of multiple elements.

[0035] It should also be noted herein that, for the sake of clarity and simplicity, only a part of the components or assemblies can be shown in the embodiments of the present application, but those skilled in the art can understand that, under the teaching of the present application, the required components or assemblies can be added according to the specific scene needs.

[0036] It should also be noted herein that, within the scope of the present application, the phrases "the same", "equal", "equal to" do not mean that the two values are absolutely equal, but allow a certain reasonable error, that is, the phrases also cover "substantially the same", "substantially equal", "substantially equal".

[0037] It should also be noted that in the description of the present application, the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not mean that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating relative importance.

[0038] In addition, the embodiments of the present application describe the process steps in a specific order, but this is only for the convenience of distinguishing between steps, and does not limit the order of the steps, and in different embodiments of the present application, the order of the steps can be adjusted according to the adjustment of the process. In addition, the numbering of the steps is only for the purpose of referring to specific steps, and does not limit the execution order of the steps.

[0039] The arrangement of the reaction flywheel set in the following embodiments adopts a four-inclined arrangement.

[0040] Embodiment 1

[0041] The present embodiment provides a maximum energy efficiency control method for a reaction flywheel set, which is applied to a certain satellite attitude control system equipped with four reaction flywheels (FwA, FwB, FwC, FwD). The method sets the saturation protection threshold of the reaction flywheel speed to 2500r / min, and sets the upper limit of the reaction flywheel speed to 3490r / min, so as to control the satellite attitude by using the reaction flywheel set.

[0042] It is assumed that a certain satellite equipped with a reaction flywheel set performs reaction flywheel PID control at an initial angular velocity [2.00 2.00 0.47]° / s, and the target angular velocity is [0 0 0]° / s, so as to control the satellite angular velocity module value to decrease. Figure 1The figure shows the actual speed of the reaction flywheel group in the satellite attitude control process in this embodiment. It can be seen that the actual speed of the reaction flywheel A reaches the saturation protection threshold 2500r / min at the control time of 85 seconds, and then the actual speed of the reaction flywheel A remains at this speed, and the satellite attitude control is performed by the other three flywheels. The actual speed of the reaction flywheel B also reaches the saturation protection threshold 2500r / min at the control time of 150 seconds, and then the reaction flywheel A and the reaction flywheel B start to alternately increase the actual speed of the reaction flywheel until both of them reach the upper limit of the reaction flywheel speed 3490r / min at the control time of 220 seconds. The angular velocity of the satellite finally decreases to [0.42 0.30 0.47]° / s, and the angular velocity module decreases by 2.17° / s.

[0043] After the attitude control, the angular velocity is significantly reduced, indicating that the satellite attitude changes greatly, and the adjustment effect of the satellite attitude control of the reaction wheel group is obvious.

[0044] Embodiment 2

[0045] The difference between this embodiment and embodiment 1 is only that the saturation protection threshold of the reaction flywheel speed is set, and the rest of the conditions are the same as in embodiment 1. That is, a satellite equipped with a reaction flywheel group is assumed to perform 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. The control satellite angular velocity module is reduced, and the saturation protection threshold of the reaction flywheel speed is not set.

[0046] Figure 2 The figure shows the actual speed of the reaction flywheel group in the satellite attitude control process in this embodiment. It can be seen that the actual speed of the reaction flywheel A reaches the reaction flywheel speed upper limit 3490r / min at the control time of 125 seconds, and then the actual speed of the reaction flywheel A remains at this speed, and the satellite attitude control is performed by the other three reaction flywheels. The actual speed of the reaction flywheel B also reaches the reaction flywheel speed upper limit 3490r / min at the control time of 190 seconds. The angular velocity of the satellite finally decreases to [0.37 0.38 0.54]° / s, and the angular velocity module decreases 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.

[0047] By comparing the above embodiment 1 with embodiment 2, it can be seen that the angular velocity drop degree of embodiment 1 is greater than that of embodiment 2, that is, the angular velocity drop degree of the method of setting the saturation protection threshold of the reaction flywheel speed is greater than that of the method of not setting the saturation protection threshold of the reaction flywheel, which shows that after the saturation protection threshold is set, 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 and more fully compensate angular momentum, and then the satellite angular velocity drop degree is greater.

[0048] Therefore, by using the maximum energy efficiency control method of the reaction flywheel group in the application, the reaction flywheel group can more effectively utilize the change of its own angular momentum to provide more suitable reaction torque for the satellite, and the angular momentum compensation capability of the flywheel can be maximized.

[0049] Although some embodiments of the present application have been described in the present application, those skilled in the art can understand that these embodiments are only shown as examples. Those skilled in the art can think of numerous variants, alternatives and improvements under the teaching of the present application without going beyond the scope of the present application. The appended claims are intended to define the scope of the present application and thereby cover the methods and structures within the scope of the claims themselves and their equivalent transformations.

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 flywheel 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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