Permanent magnetic momentum ball for attitude adjustment of small spacecraft

Abstract

The application discloses a permanent magnetic momentum ball for attitude adjustment of a small spacecraft, which comprises a stator, a rotor and a supporting structure, the stator has a spherical cavity, coils are installed at six vertex positions of the spherical cavity by means of pole yokes to form a spherical inner cavity for accommodating the rotor; the rotor is arranged in the spherical inner cavity and has a pair of disc-shaped magnetic conductive bridges, a pair of permanent magnets with opposite polarities are symmetrically arranged on the outer ring surface of each magnetic conductive bridge in a radial direction, and the permanent magnets are magnetized along the radial direction of the spherical inner cavity; the supporting structure is a T-shaped rod, the upper end of the vertical rod of the T-shaped rod is rotatably supported on a beam component of the stator by means of a bearing to realize self-rotation of the rotor; the pair of magnetic conductive bridges are rotatably arranged at two ends of the horizontal rod by means of bearings to realize overturning motion of the rotor; the self-rotation and overturning motion of the permanent magnetic momentum ball are realized by changing the current of the coils, thereby realizing momentum exchange and adjusting the attitude of the spacecraft. The application has high power density, large output torque, high and adjustable rotating speed and stable structure.

Description

Technical Field

[0001] This invention relates to a momentum sphere, and more specifically to a permanent magnet momentum sphere for attitude control of small spacecraft. Background Technology

[0002] With the development of aerospace technology, the importance of spacecraft miniaturization has become increasingly prominent. A major problem affecting spacecraft miniaturization lies in the complexity of the spacecraft attitude control system. The spacecraft attitude control system is a crucial subsystem used to prevent spacecraft from flipping and to adjust the spacecraft's attitude in a timely manner. Based on their operating principles, current attitude control systems can be mainly divided into two types: mass expulsion type and momentum exchange type. Mass expulsion type control systems generate thrust by expelling high-speed gas to drive attitude changes. This method can generate large thrust but has lower control accuracy, and because it requires a continuous fuel supply, it is generally only suitable for spacecraft with short-term flights or manned spacecraft. In contrast, momentum exchange type control systems, based on the law of conservation of angular momentum, adjust the attitude of the spacecraft body by changing the angular momentum of the rotary actuators within the control system. This method has higher control accuracy but lower output torque. It can be powered by solar panels and is suitable for attitude control of small spacecraft with long-term flights. Compared to mass expulsion control, this method can only cause the spacecraft body to rotate around its center of mass to change its attitude, but cannot cause it to translate.

[0003] Currently, the most commonly used angular momentum exchange actuators in spacecraft are control moment gyroscopes and flywheels. Control moment gyroscopes rotate at a fixed speed, and their output torque can be changed by altering the direction of their rotation axis. Flywheels generate torque through the acceleration and deceleration of rotating wheels, with their rotation axis remaining constant relative to the spacecraft body. Since a single rotating wheel can only change momentum in a single direction, an attitude control system often requires at least three rotating wheels, resulting in structural redundancy. Simplifying a set of momentum exchange actuators into a single momentum sphere avoids coupling effects between different actuators, thus simplifying controller design. Compared to control moment gyroscopes and flywheels, the momentum sphere, thanks to its momentum storage component, enables multi-degree-of-freedom rotation and acceleration, thus achieving all the functions of control moment gyroscopes and flywheels. Existing momentum spheres can be divided into inductive momentum spheres and permanent magnet momentum spheres. Using a spherical rotor as a momentum exchange device can simultaneously achieve momentum exchange in three degrees of freedom. Inductive momentum spheres have large rotor volume, high drive current, significant temperature rise, and low power density, which is unfavorable for the miniaturization and high efficiency requirements of spacecraft. Traditional permanent magnet momentum spheres have a large number of permanent magnets on their spherical rotors, which pose risks of electromagnetic interference and demagnetization, making them difficult to apply in practice. Therefore, existing momentum spheres cannot meet the requirements of miniaturization, high efficiency and safety and reliability for attitude control of micro spacecraft. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, this invention provides a small permanent magnet momentum sphere for spacecraft attitude adjustment that features high power density, large output torque, high and adjustable rotation speed, and stable structure. By changing the on / off state of the stator coil, the magnitude of the coil current, and the direction of energization, the position of the magnetic flux path can be controlled, thereby realizing the spin and flipping motion of the permanent magnet momentum sphere and adjusting its rotation speed to achieve momentum exchange and adjust the spacecraft attitude.

[0005] The present invention adopts the following technical solution to solve the technical problem:

[0006] The permanent magnet momentum sphere for attitude adjustment of small spacecraft of the present invention is characterized by comprising a stator, a rotor, and a support structure; the stator has a spherical cavity, and coils are installed at the six vertices of the spherical cavity using pole yokes to form a spherical inner cavity for accommodating the rotor; the rotor is disposed in the spherical inner cavity, and the rotor has a pair of parallel and spaced disk-shaped magnetic bridges, with a pair of permanent magnets of opposite polarity arranged radially symmetrically on the outer ring surface of each magnetic bridge, the permanent magnets being magnetized along the radial direction of the spherical inner cavity; the support structure is a "T"-shaped rod, the upper end of the vertical rod of the "T"-shaped rod is rotatably supported on the beam component of the stator by a bearing; the pair of magnetic bridges are respectively rotatably disposed at both ends of the horizontal rod through bearings, allowing the rotor to rotate within the spherical inner cavity.

[0007] The features of the permanent magnet momentum sphere for attitude adjustment of small spacecraft in this invention are also as follows:

[0008] The stator is a rectangular frame with a spherical cavity, which is constructed from various beam components. On the inner wall of the rectangular frame, at the top, bottom, left, right, front and rear of the spherical cavity, the coils are installed using pole yokes protruding into the spherical cavity on the beam components.

[0009] The permanent magnet momentum ball for attitude adjustment of small spacecraft of the present invention is also characterized in that the beam components constituting the stator are the first stator beam and the second stator beam.

[0010] The first stator beam has a top groove in the middle, and the second stator beam has a bottom groove in the middle. The first stator beam and the second stator beam are connected in a cross shape by interlocking the top groove and the bottom groove in the middle.

[0011] The first stator beam has protruding tenons on both end faces, and the second stator beam has mortises on both sides. The first stator beam and the second stator beam are connected at the ends by tenon and mortise joints to form a corner connection.

[0012] The permanent magnet momentum ball for attitude adjustment of small spacecraft in this invention is also characterized by the fact that the pole yoke set on the stator beam component is boot-shaped, with the upper straight section hanging on the beam component and the lower arc section hanging on the coil.

[0013] The permanent magnet momentum sphere for attitude adjustment of small spacecraft in this invention is also characterized by defining the coils set at different positions inside the spherical cavity in a one-to-one correspondence with the X-axis, Y-axis and Z-axis as follows:

[0014] The coils located at the front and rear pole yokes are the X-axis coils;

[0015] The coils located at the left and right pole yokes are Y-axis coils;

[0016] The coils located at the upper and lower pole yokes are Z-axis coils;

[0017] The drive method for the rotor is set as follows:

[0018] By energizing the X-axis coil and Y-axis coil, the rotor is driven to move continuously, thereby realizing the rotor's flipping motion around the Z-axis;

[0019] By energizing the Z-axis coil and the X-axis coil, the rotor is driven to move continuously, thereby realizing the rotor's spin motion on the Y-axis;

[0020] By energizing the Z-axis coil and the Y-axis coil, the rotor is driven to move continuously, thereby realizing the rotor's spin motion on the X-axis.

[0021] Compared with existing technologies, the beneficial effects of this invention are reflected in:

[0022] 1. The permanent magnet momentum ball for attitude adjustment of small spacecraft of the present invention is small in size, simple to control, and has a high rotation speed. It can replace the traditional spacecraft attitude adjustment device in some demanding situations, thereby reducing the cumbersome structure.

[0023] 2. The permanent magnet momentum sphere of this invention is based on the principle of minimum magnetic reluctance. By changing the direction of the current in the coil winding, the magnetic flux path is altered, attracting the rotor structure to rotate or flip. When the coil is energized, it generates magnetic flux, which, together with the stator beam, rotor permanent magnet, and magnetic conductor, forms a magnetic flux path, generating an electromagnetic force on the rotor structure and driving the momentum sphere to perform the corresponding motion.

[0024] 3. In this invention, the permanent magnets are all fixed in the rotor, and the stator only has rotor teeth made of magnetic material. The structure is simple, the heat dissipation effect is good, and the output torque can be provided by changing the ampere-turns of the coil. The rotor speed can be adjusted by changing the coil energizing frequency. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of the permanent magnet momentum sphere of the present invention.

[0026] Figure 2 This is a schematic diagram of the beam components that constitute the stator in this invention.

[0027] Figure 3 This is a schematic diagram of another beam component that constitutes the stator in this invention.

[0028] Figure 4 This is a schematic diagram of the assembly of the beam components that constitute the stator in this invention.

[0029] Figure 5 This is a schematic diagram of the structure in which the magnetic bridge and permanent magnet are combined in this invention.

[0030] Figure 6 This is a schematic diagram of the support structure in this invention.

[0031] Figure 7 This is a schematic diagram of the cooperation between the rotor and the support structure in this invention.

[0032] Figure 8 This is a schematic diagram of the driving module in this invention.

[0033] Figure 9 This is a schematic diagram of the spin motion of the present invention.

[0034] Figure 10 This is a schematic diagram of the flipping motion of the present invention.

[0035] Figure 11 This is the spin motion torque curve of the present invention.

[0036] Figure 12 The present invention is used to reverse the motion torque curve.

[0037] The following are the labels in the diagram: 1 First stator beam, 1a Top groove, 1b Tenon, 2 Second stator beam, 2a Bottom groove, 2b Mortise, 3 Drive coil, 4 Pole yoke, 5 Permanent magnet, 6 Magnetic bridge, 7 Support structure, 10 Vertical rod, 11 First bearing, 12 Second bearing. Detailed Implementation

[0038] See Figure 1 , Figure 5 , Figure 6 and Figure 7 In this embodiment, the permanent magnet momentum sphere for attitude adjustment of a small spacecraft includes a stator, a rotor, and a support structure 7. The stator has a spherical cavity, and coils 4 are installed at the six vertices of the spherical cavity using a pole yoke to form a spherical inner cavity for accommodating the rotor. The rotor is disposed in the spherical inner cavity and has a pair of parallel and spaced disk-shaped magnetic bridges 6. A pair of permanent magnets 5 with opposite polarities are radially symmetrically arranged on the outer ring surface of each magnetic bridge 6, and the permanent magnets 5 are magnetized in the radial direction of the spherical inner cavity. The support structure 7 is a "T"-shaped rod. The upper end of the vertical rod 10 in the "T"-shaped rod is rotatably supported on the beam member of the stator by a first bearing 11, realizing the self-spinning motion of the rotor. The pair of magnetic bridges 6 are respectively rotatably disposed at both ends of the horizontal rod through a second bearing, realizing the flipping motion of the rotor.

[0039] In practice, the corresponding technical measures include:

[0040] like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, the stator is a rectangular frame with a spherical cavity, which is constructed from various beam components. On the inner wall of the rectangular frame, at the top, bottom, left, right, front and rear of the spherical cavity, the coils 3 are installed using the pole yokes 4 protruding into the spherical cavity on the beam components. The beam components that make up the stator are the first stator beam 1 and the second stator beam 2.

[0041] Figure 2 The first stator beam 1 shown has a top surface groove 1a in the middle. Figure 3 The second stator beam 2 shown has a bottom groove 2a in the middle. The first stator beam 1 and the second stator beam 2 are connected in the middle by interlocking the top groove 1a and the bottom groove 2a to form a cross. Figure 2 The first stator beam 1 shown has protruding tenons 1b on both end faces, and the second stator beam 2 has mortises 2b on both sides. The first stator beam 1 and the second stator beam 2 are connected at their ends by tenon and mortise joints to form a corner connection; as shown Figure 2 and Figure 3 As shown, in this embodiment, the pole yoke 4 set on the stator beam component is boot-shaped, with the upper straight section hanging on the beam component and the lower arc section hanging on the coil 3; this structural form can effectively improve the structural stability and heat dissipation effect of the permanent magnet momentum ball, and avoid the risk of demagnetization of the rotor permanent magnet due to poor heat dissipation effect.

[0042] exist Figure 5 and Figure 7 In the rotor structure shown, the end faces of the magnetic bridges symmetrically located on both sides of the support structure are parallel to each other. The permanent magnets 5 set on the magnetic bridges 6 have the same thickness as the magnetic bridges, which is 5mm. The permanent magnet arc surface opening of each section of the permanent magnet 5 is 120° and the radial length is 5mm. The center of the magnetic bridge 6 is a cylindrical hole with a diameter of 10mm, which is used to cooperate with the second bearing 12 for installation.

[0043] The coils positioned at different locations within the spherical cavity are defined one-to-one with the X-axis, Y-axis, and Z-axis as follows: the coils located at the front and rear pole yokes are X-axis coils; the coils located at the left and right pole yokes are Y-axis coils; and the coils located at the upper and lower pole yokes are Z-axis coils. The driving method for the rotor is set as follows: energizing the X-axis and Y-axis coils drives the rotor to move continuously, achieving the rotor's rotational motion around the Z-axis; energizing the Z-axis and X-axis coils drives the rotor to move continuously, achieving the rotor's spin motion on the Y-axis; and energizing the Z-axis and Y-axis coils drives the rotor to move continuously, achieving the rotor's spin motion on the X-axis.

[0044] like Figure 1 and Figure 8As shown, in specific implementation, the drive module includes two sets of spin modules and one set of flip modules. The two types of modules drive different motions and serve as backups for each other. Figure 8 The diagram shows the X-axis spin module (phases X1 and X2), the Y-axis spin module (phases Y1 and Y2), and the Z-axis flip module (phases Z1 and Z2). The rotor permanent magnets are radially magnetized, and the permanent magnets at both ends are not of the same pole; their magnetic field lines run from the N pole to the S pole. Current is passed through the coils closest to the permanent magnets, generating magnetic field lines in the same or opposite direction as the permanent magnets. Based on the principle of minimum magnetic reluctance, the magnetic circuit always closes with the path of least magnetic reluctance. Therefore, the coils closest to the permanent magnets generate a magnetic path in the same direction as the permanent magnets, attracting the permanent magnets to rotate towards the center of the coils; the coils farther from the permanent magnets generate a magnetic path in the opposite direction, repelling the permanent magnets away from the center of those coils. The driving principles for the X-axis and Y-axis spin motions and the Z-axis flip motion are the same. This embodiment explains the mechanism of the X-axis spin motion and the Z-axis flip motion.

[0045] Figure 9 The diagram illustrates the spin motion. When the rotor is positioned vertically at the center of the X-axis, coils Z1, Z2, X1, and X2 are energized, causing the rotor to rotate. Coils X1 and X2 generate magnetic flux in the opposite direction to the rotor's permanent magnet flux, driving the rotor away from them. Coils Z1 and Z2 are energized in the same direction, generating magnetic flux in the same direction as the rotor's permanent magnet flux, driving the rotor to rotate in the Z-axis direction. If the magnetic flux generated by coils Z1 and Z2 is in the same positive Z-axis direction as the rotor's permanent magnet flux, the rotor rotates in the positive Z-axis direction, i.e., clockwise. If the magnetic flux generated by coils Z1 and Z2 is in the same negative Z-axis direction as the rotor's permanent magnet flux, the rotor rotates in the negative Z-axis direction, i.e., counterclockwise.

[0046] Figure 10 The diagram illustrates the rotation motion. When the rotor is positioned vertically at the center of the Y-axis, coils X1, X2, Y1, and Y2 are energized, causing the rotor to rotate. Coils Y1 and Y2 generate magnetic flux in the opposite direction to the rotor's permanent magnet flux, driving the rotor away from them. Coils X1 and X2 are energized in the same direction, generating magnetic flux in the same direction as the rotor's permanent magnet flux, driving the rotor to rotate in the X-axis direction. If the magnetic flux generated by coils X1 and X2 is in the same positive direction as the rotor's permanent magnet flux, the rotor rotates in the positive X-axis direction, i.e., clockwise. If the magnetic flux generated by coils X1 and X2 is in the same negative X-axis direction as the rotor's permanent magnet flux, the rotor rotates in the negative X-axis direction, i.e., counterclockwise.

[0047] In this embodiment, the motion of the permanent magnet momentum ball used for attitude adjustment in a small spacecraft is achieved by the torque generated by the electromagnetic force of the interaction between the stator and rotor. Each drive unit is modularly and independently configured, and the two are organically and fault-tolerantly combined to achieve multi-degree-of-freedom motion. Compared with the complex drive control methods of traditional spacecraft attitude adjustment mechanical devices, the modular drive units have good decoupling properties, which is beneficial for complex motion decoupling analysis and facilitates control. For spin and tumbling motions, the rotor achieves three-degree-of-freedom motion by adjusting the on / off state and magnitude of the current in different stator winding coils. The rotation of the rotor structure, through momentum exchange, causes the load to move according to the designed motion pattern.

[0048] Figure 11 The diagram shows that under multi-coil energization, the rotor structure's output torque remains positive during spin motion, indicating that the rotor structure can spin according to the set excitation. The rotor torque increases accordingly under different excitations. During the increase from 400AT to 700AT, the peak electromagnetic torque increases from 65mNm to 120mNm.

[0049] Figure 12 The diagram shows that under multi-coil energization, the rotor structure's output torque remains positive during the tumbling motion, indicating that the rotor structure can perform tumbling motion according to the set excitation. The rotor torque increases accordingly under different excitations. During the increase from 500AT to 700AT, the peak electromagnetic torque increases from 85mNm to 116mNm.

[0050] Based on the above-described preferred embodiments of the present invention, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A permanent magnetic momentum ball for attitude adjustment of a small spacecraft, characterized in that It includes a stator, a rotor and a support structure; the stator has a spherical cavity, coils are installed at six vertex positions of the spherical cavity by using pole yokes to form a spherical inner cavity for accommodating the rotor; the rotor is arranged in the spherical inner cavity, and the rotor has a pair of mutually parallel and spaced apart disc-shaped magnetic conductive bridges, a pair of polar opposites permanent magnets are symmetrically arranged on the outer ring surface of each magnetic conductive bridge in the radial direction, and the permanent magnets are magnetized in the radial direction of the spherical inner cavity; the support structure is a "T" shaped rod, the upper end of the vertical rod of the "T" shaped rod is rotatably supported on the beam member of the stator by using a bearing; a pair of magnetic conductive bridges are rotatably arranged at the two ends of the horizontal rod by using bearings, so that the rotor can be turned in the spherical inner cavity; the stator is a rectangular frame with a spherical cavity which is built by beam members, and each coil (3) is installed on the pole yoke (4) which protrudes towards the spherical cavity on the inner side wall of the rectangular frame and is divided into the top, bottom, left, right, front and rear parts of the spherical cavity; the beam members constituting the stator are a first stator beam (1) and a second stator beam (2); the first stator beam (1) has a top surface groove in the middle part, the second stator beam (2) has a bottom surface groove in the middle part, and the first stator beam (1) and the second stator beam (2) are mutually embedded in the middle part by using the top surface groove and the bottom surface groove to form a "cross" connection; the first stator beam (1) has protruding tenons on the end faces of the two ends, the second stator beam (2) has mortises on the side parts of the two ends, and the first stator beam (1) and the second stator beam (2) are connected at the ends by using the mortise and tenon joint to form a corner connection; the pole yoke (4) arranged on the stator beam member is in the shape of a boot, the upper straight section is hung on the beam member, and the lower arc section hangs the coil (3).

2. The small spacecraft attitude adjustment permanent magnetic momentum ball according to claim 1, characterized in that: The coils arranged at different positions in the spherical cavity are defined as follows: the coils at the pole yokes at the front and rear parts are X-axis coils; the coils at the pole yokes at the left and right parts are Y-axis coils; the coils at the pole yokes at the upper and lower parts are Z-axis coils; the driving mode for the rotor is as follows: the X-axis coils and the Y-axis coils are energized to drive the rotor to continuously move, so as to realize the turning movement of the rotor around the Z-axis; the Z-axis coils and the X-axis coils are energized to drive the rotor to continuously move, so as to realize the spinning movement of the rotor in the Y-axis; the Z-axis coils and the Y-axis coils are energized to drive the rotor to continuously move, so as to realize the spinning movement of the rotor in the X-axis.

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