3-axis attitude control device

Abstract

A three-axis attitude control device is disclosed. The three-axis attitude control device of the present invention comprises a first CMG, a second CMG, a third CMG, a fourth CMG, and a control unit, wherein each CMG includes a motor that rotates each wheel and a gimbal motor that converts the angular momentum vector of each wheel. The axes of the first gimbal motor and the second gimbal motor are parallel to the first axis, the axes of the third gimbal motor and the fourth gimbal motor are parallel to the second axis, the angular momentum vector of the first wheel and the angular momentum vector of the second wheel are formed on the slope of the second axis, and the angular momentum vector of the third wheel and the angular momentum vector of the fourth wheel are formed on the slope of the first axis. According to the present invention, a three-axis attitude control device is provided that enables attitude control of a spacecraft, an artificial satellite, etc., even without installing a slip ring on the wheel motor.

Description

Technology Field

[0001] The present invention relates to a 3-axis attitude control device, and more specifically, to a 3-axis attitude control device configured to be used for attitude control of spacecraft, artificial satellites, etc. Background Technology

[0002] Control Moment Gyroscopes (CMGs) serve as attitude control devices, and attitude control systems utilizing them are used in spacecraft, satellites, and the like. A Control Moment Gyros includes a wheel motor that generates angular momentum by rotating a reaction wheel at high speed, and a gimbal motor that transforms the vector of the angular momentum.

[0003] While conventional motors have the advantage that the direction of the torque axis they generate is always the same as the axis to be rotated, they are difficult to generate relatively large torque. On the other hand, control moment gyroscopes have the advantage of generating relatively large torque through small gimbal angular velocities, but they have the disadvantage that the torque-generating axis continuously changes depending on the gimbal angle.

[0004] Control moment gyroscopes exhibit technical limitations due to the problem of not being able to generate torque in the direction of the desired axis, and mathematical methods are being applied to solve this problem. However, applying such methods is subject to the constraint that the rotational motion of the gimbal must be guaranteed to be 360 ​​degrees or more.

[0005] Accordingly, to properly configure the control moment gyro, a slip ring must be additionally installed. A slip ring is a component that enables the free transmission of power and data to a rotating object. Since the gimbal motor rotates freely more than 360 degrees, a slip ring must be installed to supply power to the wheel motor.

[0006] However, slip rings are components requiring high reliability to stably supply power and data to rotating objects without loss, and they are considerably expensive. Therefore, the installation of slip rings acts as a major limiting factor that reduces the usability of control moment gyroscopes. Prior art literature

[0007] Republic of Korea Registered Patent Publication No. 778098 (Registration Date: Nov. 14, 2007) The problem to be solved

[0008] The objective of the present invention is to provide a 3-axis attitude control device that enables attitude control of a spacecraft, satellite, etc., even without installing a slip ring on the wheel motor. means of solving the problem

[0009] The above objective is achieved by a 3-axis attitude control device comprising a first CMG, a second CMG, a third CMG, a fourth CMG, and a control unit, according to the present invention.

[0010] The above first CMG may comprise a first wheel motor that rotates a first wheel, and a first gimbal motor that converts the angular momentum vector of the first wheel.

[0011] The above second CMG may comprise a second wheel motor that rotates the second wheel, and a second gimbal motor that converts the angular momentum vector of the second wheel.

[0012] The above third CMG may comprise a third wheel motor that rotates the third wheel, and a third gimbal motor that converts the angular momentum vector of the third wheel.

[0013] The above-mentioned fourth CMG may comprise a fourth wheel motor that rotates the fourth wheel, and a fourth gimbal motor that converts the angular momentum vector of the fourth wheel.

[0014] The shafts of the first and second gimbal motors may be parallel to the first shaft, and the shafts of the third and fourth gimbal motors may be parallel to the second shaft.

[0015] The angular momentum vectors of the first wheel and the second wheel may be generated on the slope of the second axis, and the angular momentum vectors of the third wheel and the fourth wheel may be generated on the slope of the first axis.

[0016] The control unit may be configured to limit the rotation angle of the first wheel by the first gimbal motor, the rotation angle of the second wheel by the second gimbal motor, the rotation angle of the third wheel by the third gimbal motor, and the rotation angle of the fourth wheel by the fourth gimbal motor so that wires are directly connected to the first wheel motor, the second wheel motor, the third wheel motor, and the fourth wheel motor without a slip ring.

[0017] The control unit may be configured to limit the rotation angle of the first wheel by the first gimbal motor, the rotation angle of the second wheel by the second gimbal motor, the rotation angle of the third wheel by the third gimbal motor, and the rotation angle of the fourth wheel by the fourth gimbal motor to within ±150°, respectively.

[0018] The first axis and the second axis may be formed to be orthogonal to each other.

[0019] In addition, the above objective is achieved by a 3-axis attitude control system including the attitude control device according to the present invention. Effects of the invention

[0020] According to the present invention, by limiting the rotation angle of each wheel by each gimbal motor to a specific range and directly connecting wires to each wheel motor, it is possible to provide a 3-axis attitude control device that enables attitude control of a spacecraft, satellite, etc., without installing slip rings on the wheel motors. Brief explanation of the drawing

[0021] FIG. 1 is a drawing showing a 3-axis attitude control device and a satellite according to an embodiment of the present invention. FIG. 2 is a drawing showing a 3-axis attitude control device according to an embodiment of the present invention. FIG. 3 is a chart showing the angle of the gimbal and the momentum of the satellite according to an embodiment of the present invention. Specific details for implementing the invention

[0022] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. However, in describing the present invention, descriptions of already known functions or configurations will be omitted in order to clarify the gist of the present invention.

[0024] FIG. 1 is a drawing showing a 3-axis attitude control device (100) and a satellite (1) according to an embodiment of the present invention.

[0025] FIG. 2 is a drawing showing a 3-axis attitude control device (100) according to an embodiment of the present invention.

[0026] A 3-axis attitude control device (100) according to an embodiment of the present invention is used in an attitude control system (10) such as a spacecraft or a satellite (1).

[0027] Generally, one control moment gyroscope is required for attitude control about a single axis. Therefore, at least three control moment gyroscopes are required for 3-axis attitude control of a satellite.

[0028] However, due to the nature of space, there is a tendency to add one additional control moment gyroscope to prepare for failure. Therefore, four control moment gyroscopes are generally used for 3-axis attitude control of a satellite.

[0029] The control moment gyro (CMG) generates torque by the gyroscope effect as shown in the formula below to control the attitude of a 3-axis attitude control system (10), such as a spacecraft or satellite (1).

[0030]

[0031] Here, means the generated torque, represents the moment of inertia of the system, and represents the angular acceleration of the motor, and represents the angular velocity of the gimbal, and represents the angular momentum of the momentum wheel.

[0032] Methods for generating torque include a method that expresses it in the form of action and reaction by generating the motor's angular acceleration, and a method that expresses the angular momentum of the momentum wheel in the form of a vector product through the change in the gimbal's angle. Generally, a motor Generating torque in the same manner, the Control Moment Gyro (CMG) It generates torque in the form of...

[0033] While conventional motors have the advantage that the direction of the torque axis they generate is always the same as the axis to be rotated, they are difficult to generate relatively large torque.

[0034] On the other hand, while a control moment gyroscope has the advantage of generating relatively large torque through a small gimbal angular velocity, it has the disadvantage that the axis generating the torque continuously changes depending on the gimbal angle.

[0035] Controlled moment gyroscopes (CMGs) exhibit technical limitations due to the problem of being unable to generate torque in the direction of a desired axis, and mathematical methods are being applied to solve this problem. However, applying such methods is subject to the constraint that the rotational motion of the gimbal must be guaranteed to be 360 ​​degrees or more.

[0036] The 3-axis attitude control device (100) according to an embodiment of the present invention is configured so that attitude control of a spacecraft, satellite (1), etc. is possible even if a slip ring is installed on the wheel motor and the rotational movement of the gimbal is restricted.

[0037] As shown in FIGS. 1 and 2, in an embodiment of the present invention, two control moment gyroscopes are mounted on an arbitrary axis as a method to utilize a control moment gyroscope with a limited gimbal angle without a slip ring for attitude control of a satellite.

[0038] And the operating ranges of the two gimbals are designed to operate in opposite directions. Therefore, torque generation is possible for the two axes other than the gimbal axis.

[0039] Therefore, by mounting two control moment gyroscopes on each of two different axes (x-axis and y-axis) (see Fig. 2), 3-axis attitude control for satellite control is possible. Thus, a total of four control moment gyroscopes are utilized. In the following description, the axes on which the control moment gyroscopes are mounted are configured as the x-axis and the y-axis.

[0040] As illustrated in FIG. 2, a 3-axis attitude control device (100) according to an embodiment of the present invention includes a first CMG (110), a second CMG (120), a third CMG (130), a fourth CMG (140), and a control unit (150).

[0041] Here, CMG stands for Control Moment Gyros. A Control Moment Gyros includes a Wheel Motor that generates angular momentum by rotating a Reaction Wheel at high speed, and a Gimbal Motor that transforms the vector of angular momentum. Since Control Moment Gyros are a widely known technology in the field of attitude control, a detailed explanation thereof will be omitted.

[0042] In FIG. 1, γ1 represents the gimbal angle of the first CMG (110), and γ2 represents the gimbal angle of the second CMG (120). Also, h1 represents the two-dimensional angular momentum vector of the first CMG (110), and h2 represents the two-dimensional angular momentum vector of the second CMG (120). Also, τ1 represents the torque of the first CMG (110), and τ2 represents the torque of the second CMG (120).

[0043] The first CMG (110) includes a first wheel (Wh1), a first wheel motor (Mw1), a first gimbal motor (Mg1), and a first frame (Fr1).

[0044] The first wheel motor (Mw1) is configured to rotate the first wheel (Wh1) at high speed. The first wheel motor (Mw1) is fixed to the first frame (Fr1).

[0045] The first gimbal motor (Mg1) is configured to convert the angular momentum vector of the first wheel (Wh1) (hereinafter referred to as the 'first angular momentum vector'). The first gimbal motor (Mg1) converts the first angular momentum vector of the first wheel (Wh1) by rotating the first frame (Fr1).

[0046] The second CMG (120) includes a second wheel (Wh2), a second wheel motor (Mw2), a second gimbal motor (Mg2), and a second frame (Fr2).

[0047] The second wheel motor (Mw2) is configured to rotate the second wheel (Wh2) at high speed. The second wheel motor (Mw2) is fixed to the second frame (Fr2).

[0048] The second gimbal motor (Mg2) is configured to convert the angular momentum vector of the second wheel (Wh2) (hereinafter referred to as the 'second angular momentum vector'). The second gimbal motor (Mg2) converts the second angular momentum vector of the second wheel (Wh2) by rotating the second frame (Fr2).

[0049] The axis (x1) of the first gimbal motor (Mg1) and the second gimbal motor (Mg2) is parallel to the first axis (Y). The first axis (Y) and the second axis (X) are orthogonal to each other.

[0050] The first CMG (110) and the second CMG (120) can each generate torque in any direction of the first axis (Y) and the third axis (Z) by driving the first gimbal motor (Mg1) and the second gimbal motor (Mg2).

[0051] In FIG. 1, γ3 represents the gimbal angle of the third CMG (130), and γ4 represents the gimbal angle of the fourth CMG (140). Also, h3 represents the two-dimensional angular momentum vector of the third CMG (130), and h4 represents the two-dimensional angular momentum vector of the fourth CMG (140). Also, τ3 represents the torque of the third CMG (130), and τ4 represents the torque of the fourth CMG (140).

[0052] The third CMG (130) includes a third wheel (Wh3), a third wheel motor (Mw3), a third gimbal motor (Mg3), and a third frame (Fr3).

[0053] The third wheel motor (Mw3) is configured to rotate the third wheel (Wh3) at high speed. The third wheel motor (Mw3) is fixed to the third frame (Fr3).

[0054] The third gimbal motor (Mg3) is configured to convert the angular momentum vector of the third wheel (Wh3) (hereinafter referred to as the 'third angular momentum vector'). The third gimbal motor (Mg3) converts the third angular momentum vector of the third wheel (Wh3) by rotating the third frame (Fr3).

[0055] The 4th CMG (140) includes a 4th wheel (Wh4), a 4th wheel motor (Mw4), a 4th gimbal motor (Mg4), and a 4th frame (Fr4).

[0056] The fourth wheel motor (Mw4) is configured to rotate the fourth wheel (Wh4) at high speed. The fourth wheel motor (Mw4) is fixed to the fourth frame (Fr4).

[0057] The fourth gimbal motor (Mg4) is configured to convert the angular momentum vector of the fourth wheel (Wh4) (hereinafter referred to as the 'fourth angular momentum vector'). The fourth gimbal motor (Mg4) converts the fourth angular momentum vector of the fourth wheel (Wh4) by rotating the fourth frame (Fr4).

[0058] The axes (x2) of the third gimbal motor (Mg3) and the fourth gimbal motor (Mg4) are parallel to the second axis (X). The first axis (Y) and the second axis (X) are orthogonal to each other.

[0059] The third CMG (130) and the fourth CMG (140) can each generate torque in any direction of the second axis (X) and the third axis (Z) by driving the third gimbal motor (Mg3) and the fourth gimbal motor (Mg4), respectively.

[0060] FIG. 3 is a chart showing the angle of the gimbal and the momentum of the satellite (1) according to an embodiment of the present invention. The horizontal axis of FIG. 3 represents γ1 and γ3 (deg), and the vertical axis represents γ2 and γ4 (deg). The numbers inside the chart of FIG. 3 represent angular momentum.

[0061] In Figure 3, the yellow area represents the region where the performance of the control moment gyroscope degrades rapidly. Conventional control moment gyroscopes often fall into the yellow area because they assume the free movement of the slip ring.

[0062] The inventor of the present invention derived the chart of FIG. 3 through a number of tests and simulations. Through the chart of FIG. 3, it was determined that reliable 3-axis satellite control is possible even without installing a slip ring when limiting the angle of the gimbal (-150 degrees to 150 degrees) while applying a margin.

[0063] That is, in the 3-axis attitude control device (100) according to an embodiment of the present invention, the control unit (150) limits the rotation angle of all gimbal motors (Mg1, Mg2, Mg3, Mg4), so that the wires can be directly connected without a slip ring.

[0064] At this time, the control unit (150) can limit the rotation angle of the first wheel (Wh1) by the first gimbal motor (Mg1), the rotation angle of the second wheel (Wh2) by the second gimbal motor (Mg2), the rotation angle of the third wheel (Wh3) by the third gimbal motor (Mg3), and the rotation angle of the fourth wheel (Wh4) by the fourth gimbal motor (Mg4) to within ±150°, respectively.

[0065] In Figure 3, the blue area represents the region where performance degradation of the control moment gyroscope does not occur. Therefore, it was concluded that reliable 3-axis satellite control is possible by limiting the angle of the gimbal within the blue area, even without installing a slip ring.

[0066] At this time, the control unit (150) may limit the rotation angle of the first wheel (Wh1) by the first gimbal motor (Mg1) and the rotation angle of the third wheel (Wh3) by the third gimbal motor (Mg3) to within -45 to 130°, and limit the rotation angle of the second wheel (Wh2) by the second gimbal motor (Mg2) and the rotation angle of the fourth wheel (Wh4) by the fourth gimbal motor (Mg4) to within -130 to 44°, respectively.

[0067] A 3-axis attitude control device (100) according to an embodiment of the present invention arranges two CMGs in the same direction and selects the movement range of the gimbals to opposite ranges, thereby enabling the securing of an overall area for controlling the satellite.

[0068] Furthermore, the inventor of the present invention has developed a method to set the angle range of the gimbal of the control moment gyroscope according to the range of angular momentum utilizing the satellite. Through this, attitude control performance identical to that of existing satellites can be guaranteed.

[0069] Accordingly, the 3-axis attitude control device (100) according to the embodiment of the present invention has a somewhat limited torque generation range due to the limitation of the gimbal operation angle, but it can be applied to a system requiring reliability regarding singularities, and is particularly suitable for 3-axis attitude control of an artificial satellite (1).

[0070] According to the present invention, by limiting the rotation angle of the wheels (Wh1, Wh2, Wh3, Wh4) by all gimbal motors (Mg1, Mg2, Mg3, Mg4) to a specific range, it is possible to provide a 3-axis attitude control device (100) that enables attitude control of a spacecraft, satellite (1), etc., even without installing a slip ring on the wheel motor.

[0072] Although specific embodiments of the present invention have been described and illustrated above, it is obvious to those skilled in the art that the present invention is not limited to the described embodiments and can be modified and varied in various ways without departing from the spirit and scope of the present invention. Accordingly, such modifications or variations should not be understood individually from the technical spirit or perspective of the present invention, and the modified embodiments should be considered to fall within the scope of the claims of the present invention. Explanation of the symbols

[0073] 10: 3-axis attitude control system 100 : 3-axis attitude control unit 110 : 1st CMG Wh1 : 1st Wheel 120 : 2nd CMG Mw1 : 1st wheel motor 130 : 3rd CMG Mg1 : 1st Gimbal Motor 140 : 4th CMG Fr1 : 1st Frame 150 : Control unit Wh2 : Second wheel Y : 1st axis Mw2 : 2nd wheel motor X : 2nd axis Mg2 : 2nd gimbal motor 1 : Satellite Fr2 : 2nd Frame Wh3: 3rd wheel Wh4: 4th wheel Mw3: 3rd wheel motor Mw4: 4th wheel motor Mg3 : 3rd Gimbal Motor Mg4 : 4th Gimbal Motor Fr3: 3rd frame Fr4: 4th frame

Claims

Claim 1 The apparatus comprises a first CMG, a second CMG, a third CMG, a fourth CMG, and a control unit, wherein the first CMG comprises a first wheel motor that rotates a first wheel and a first gimbal motor that converts the angular momentum vector of the first wheel, the second CMG comprises a second wheel motor that rotates a second wheel and a second gimbal motor that converts the angular momentum vector of the second wheel, the third CMG comprises a third wheel motor that rotates a third wheel and a third gimbal motor that converts the angular momentum vector of the third wheel, and the fourth CMG comprises a fourth wheel motor that rotates a fourth wheel and a fourth gimbal motor that converts the angular momentum vector of the fourth wheel, wherein the axes of the first gimbal motor and the second gimbal motor are parallel to the first axis, and the axes of the third gimbal motor and the fourth gimbal motor are parallel to the second axis, and the first wheel and the second wheel The angular momentum vector is generated on the slope of the second axis, and the angular momentum vectors of the third wheel and the fourth wheel are generated on the slope of the first axis; and the control unit limits the rotation angle of the first wheel by the first gimbal motor, the rotation angle of the second wheel by the second gimbal motor, the rotation angle of the third wheel by the third gimbal motor, and the rotation angle of the fourth wheel by the fourth gimbal motor so that wires are directly connected to the first wheel motor, the second wheel motor, and the fourth wheel motor without slip rings, and the control unit limits the rotation angle of the first wheel by the first gimbal motor, the rotation angle of the second wheel by the second gimbal motor, the rotation angle of the third wheel by the third gimbal motor, and the rotation angle of the fourth wheel by the fourth gimbal motor to within ±150°, respectively. 3-axis attitude control device. Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 A three-axis attitude control system comprising the three-axis attitude control device of claim 1.

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