Sphere magnetic levitation system and method of operating sphere magnetic levitation system

Provided is a sphere magnetic levitation system having magnetic-aligning devices that magnetically align the position of a sphere levitated by electromagnets according to whether the sphere is levitated, and a method of operating the sphere magnetic levitation system. The sphere magnetic levitation system includes: a sphere; a plurality of electromagnets symmetrically positioned about the sphere and spaced apart from the sphere at equal distances; and a plurality of magnetic-aligning devices provided around the sphere, and coming into contact with the sphere or separated from the sphere by a predetermined distance according to the modes of the system. The system is operated in one mode from among: an idle mode, in which the magnetic-aligning devices are in direct contact with and support the sphere; and an operation mode, in which the magnetic-aligning devices are separated from the sphere and the sphere is levitated and rotated.

TECHNICAL FIELD

The present invention generally relates generally to a magnetic levitation system. More particularly, the present invention relates to a sphere magnetic levitation system capable of automatically aligning a sphere regardless of a mode by providing magnetic-aligning devices on the periphery of the sphere, and a method of operating the sphere magnetic levitation system.

BACKGROUND ART

In general, a spacecraft, such as an artificial satellite that obtains information while orbiting around the earth, is provided with an attitude control system for controlling an attitude thereof along a track. The attitude control system is configured such that a driving force generated by a reaction wheel or a thruster is exerted on the spacecraft in a desirable direction as needed, and thereby the attitude of the spacecraft is controlled. To accurately and precisely control the attitude of the spacecraft, the driving force should be respectively applied in axial directions of three axes that are perpendicular to each other, such as the x-axis, y-axis and z-axis.

Recently, a spacecraft attitude control system using a sphere, in which the attitude of the spacecraft is controlled by using a single actuator, has been actively researched, wherein a plurality of electromagnets is provided and spaced apart from each other at 90 degrees on the periphery of a sphere that is disposed in the center of the three axes, and a current is periodically applied to the electromagnets such that a rotating magnetic field is generated on the periphery of the sphere, and thereby the driving force is simultaneously exerted on the three axes by Lorentz force exerted on the sphere.

When the spacecraft attitude control system using the sphere is used to control the attitude of the spacecraft, a computer simulation is performed in advance in order to test reliability and control performance of the spacecraft attitude control system. To perform a simulation, another electromagnet is disposed at an upper portion of the attitude control system, and the sphere is levitated by a magnetic field generated by the electromagnet without falling off by the gravity, thereby staying at a predetermined position, which is disclosed in Korean Patent Application publication No. 10-2014-0014634 as “Sphere magnetic levitation system”.

Referring toFIG. 1, the conventional sphere magnetic levitation system100is capable of rotating a sphere10in a predetermined direction in a state where the sphere10is levitated by using electromagnetic force generated from a plurality of electromagnets20disposed on the periphery of the sphere10. The sphere magnetic levitation system100shown inFIG. 1is configured such that the sphere10is levitated by the electromagnetic force, and then rotates without mechanical contact with surrounding components, whereby it is possible to generate high-speed torque with low power consumption.

However, the conventional sphere magnetic levitation system (100) shown inFIG. 1is problematic for the following reasons.

When the sphere10is not levitated by the electromagnets20, the sphere10is not suspended, so when moving the system100or changing the direction thereof, the sphere10and the electromagnets20may be damaged by an impact against the surrounding components caused by vibrations.

When the sphere10is levitated by the electromagnets20, that is, when the sphere10rotates at a high speed, an impact between the sphere10and the surrounding components may occur by losing the levitation force, causing damage to the entire system100when the entire system100is out of order or power is cut off due to unforeseen reasons.

To solve the problem described above, a method that mechanically holds the sphere10by using a support frame and a ball bearing may be devised. However, in this case, a mechanical friction force may occur because of no magnetic levitation effect, whereby the sphere may not rotate at a high speed, and power consumption may be increased.

DISCLOSURE

Technical Problem

Accordingly, the present invention has been made keeping in mind the above problems occurring in the related art, and the present invention is intended to propose a sphere magnetic levitation system having magnetic-aligning devices that magnetically align the position of a sphere levitated by electromagnets according to whether the sphere is levitated by being provided on the periphery of the sphere.

The present invention is further intended to propose a method of operating the sphere magnetic levitation system.

Technical Solution

In order to achieve the above object, according to one aspect of the present invention, there is provided a sphere magnetic levitation system, including: a sphere; a plurality of electromagnets symmetrically disposed about the sphere and spaced apart from the sphere at equal distances; and a plurality of magnetic-aligning devices provided on a periphery of the sphere, and coming into contact with or being separated from the sphere at a predetermined distance in response to modes of the sphere magnetic levitation system.

In order to achieve the above object, according to another aspect of the present invention, there is provided a method of operating a sphere magnetic levitation system according to the present invention, wherein the sphere magnetic levitation system is operated in one mode between an idle mode and an operation mode, the idle mode for supporting the sphere in a state where the magnetic-aligning devices come into direct contact with the sphere; and the operation mode for rotating the sphere by levitating the sphere in a state where the magnetic-aligning devices are separated from the sphere.

Advantageous Effects

According to the present invention having the above-described characteristics, a sphere magnetic levitation system and a method of operating the same are advantageous in that the sphere may not be damaged by friction with other components constituting the sphere magnetic levitation system both in an operation mode where the sphere is levitated and rotates and in an idle mode where the sphere is neither levitated nor rotates, and when the sphere magnetic levitation system is out of order, such as when power is not provided, it is possible to prevent damage to the sphere by activating the idle mode.

BEST MODE

The invention disclosed herein will be understood better with reference to the accompanying drawings.

FIG. 2is a view showing a sphere magnetic levitation system200according to the present invention.

FIG. 3is a partial perspective view showing the sphere magnetic levitation system ofFIG. 2.

Referring toFIGS. 2 and 3, the sphere magnetic levitation system200according to the present invention includes: a sphere210, electromagnets220, magnetic-aligning devices230, an electromagnet control unit240, and a solenoid valve control unit250.

The sphere210is made of a material allowing the sphere to be levitated by a magnetic field generated by six electromagnets220.

Two of the six electromagnets220are disposed respectively in three axes, namely x-axis, y-axis, and z-axis, that are perpendicular to each other based on the center of the sphere210, and it is preferred that the electromagnets are disposed apart from the center of the sphere at equal distances in the positive (+) direction and in the negative (−) direction. For conciseness of description, six electromagnets are provided according to an embodiment of the present invention, but not limited thereto. Twelve electromagnets are provided in Korean Patent No. 10-1357599. Further, according to the embodiment of the present invention, the electromagnets are provided based on the three axes, but it is possible that a plurality of electromagnets are symmetrically disposed about the sphere210and spaced apart from the sphere210at equal distances.

A plurality of magnetic-aligning devices230is provided on a periphery of the sphere210, and comes into contact with or is separated from the sphere210at a predetermined distance in response to modes of the sphere magnetic levitation system200. Herein, the modes of the sphere magnetic levitation system200include: an idle mode for allowing the sphere neither to be levitated nor to rotate; and an operation mode for allowing the sphere to be levitated and rotate when the sphere magnetic levitation system200is operated.

The sphere magnetic levitation system200according to the present invention supports the sphere210in a state where the magnetic-aligning devices230come into direct contact with the sphere210in the idle mode. Accordingly, thanks to the bearing power, when moving the entire system100or changing the direction thereof, the sphere10and the electromagnets20may not be damaged by vibrations. In the operation mode, the sphere210is levitated by the magnetic field generated by the electromagnets220, and the magnetic-aligning devices230are separated from the sphere210at a predetermined distance, so a mechanical friction force between the sphere210and the magnetic-aligning devices230is prevented, and thereby levitation and rotation of the sphere210are facilitated.

As described above, the sphere magnetic levitation system200according to the present invention limits the movement of the sphere210by coming into contact with the sphere210in the idle mode, and levitates the sphere210in the operation mode, and thereby the sphere210is prevented from being damaged by the friction with surrounding components both in the idle mode and in the operation mode. The sphere magnetic levitation system200according to the present invention is operated in the idle mode, which will be described hereinafter, when the system is out of order, such as when power is not provided, so damage to the sphere210is prevented, which is not prevented in the conventional system.

Reference will be made to a state of the magnetic-aligning devices230in the idle mode and in the operation mode, hereinafter.

The electromagnet control unit240serves to control movements of the six electromagnets220, wherein the electromagnet control unit allows the electromagnets220to generate a magnetic field having a predetermined size by supplying power to the electromagnets220. The solenoid valve control unit250outputs the solenoid control signal (CON) and supplies power to the solenoid valve230.

Referring toFIG. 2, the solenoid valve control unit250includes: a controller (not shown) activating the solenoid control signal (CON); a solenoid valve power supply252supplying power to the solenoid valve230; and a solenoid valve control switch251switching on/off the solenoid valve power supply252and the electromagnetic coil of the solenoid valve230in response to the solenoid control signal (CON). Hereinafter, reference will be made to the electromagnetic coil constituting the solenoid valve230, hereinafter.

Though not shown in detail inFIG. 3, it is preferred that the electromagnet control unit240and the solenoid valve control unit250are powered by the power supplied from a common power supply (not shown). In this case, when external power, namely the power supplied from the common power supply, is cut, the system200under the operation mode is quickly operated in the idle mode, and thereby damage to the entire system200is prevented.

FIG. 4is a detail view showing the magnetic-aligning devices.

The ball transfer410includes: a ball cup414; a plurality of support balls413seated on a hemispherical surface formed inside the ball cup414; the main ball411provided on top of the plurality of support balls412; and a cover412covering all of the plurality of support balls413and a portion of the main ball411from a side surface of the ball cup414.

The solenoid valve420includes: a body421; a spring424provided at a lower center of the body421; a plunger422with a first end thereof being disposed at an upper portion of the spring424and a second end thereof being connected to a lower portion of the ball cup414; and an electromagnetic coil423surrounding the spring424and provided at a side surface of the body421.

The term “plunger” collectively refers to a machine part, similar to a piston that moves reciprocatingly in order to compress or discharge a fluid. In the present invention, the term “plunger422” is used to refer to an element that is disposed at the upper portion of the spring424, in consideration of the reciprocating motion of the element.

Reference will be made in detail to an operation of the magnetic-aligning devices230, hereinbelow.

FIG. 5shows an operational state in the idle mode.

The left view ofFIG. 5shows a state of the magnetic-aligning devices230, and the right view ofFIG. 5shows a location relation between the plurality of magnetic-aligning devices230and the sphere210.

Referring toFIG. 5, in the idle mode, the solenoid valve control switch251is turned off, and the electromagnetic coil is not supplied with power from the solenoid valve power supply252, so the electromagnetic coil423cannot generate the magnetic field. Accordingly, the plunger422pushes up the ball cup414by the power of the spring424. Thereby, the main ball411provided at an upper portion of the ball cup414comes into direct contact with the sphere210, and physically supports the sphere210.

FIG. 6shows an operational state in the operation mode.

The left view ofFIG. 6shows a state of the magnetic-aligning devices230, and the right view ofFIG. 6shows a location relation between the plurality of magnetic-aligning devices230and the sphere210.

Referring toFIG. 6, in the operation mode, the solenoid valve control switch251is turned on, and the electromagnetic coil is supplied with power from the solenoid valve power supply252, so the electromagnetic coil423generates a magnetic field601having a predetermined size according to the supplied power. When a direction of the magnetic field501is set to a direction compressing the spring424, the spring424is compressed, and accordingly the plunger422pulls down the ball cup414. Thus, the main ball411provided at the upper portion of the ball cup414is separated from the sphere210.

The dotted lines shown in the left views ofFIGS. 5 and 6refer to contact surfaces with the sphere210, wherein in the idle mode shown inFIG. 5, the main ball411comes into contact with the sphere210, and on the contrary, in the operation mode shown inFIG. 6, the main ball411is separated from the sphere210by a distance of arrow.

As described above, the sphere magnetic levitation system200according to the present invention is capable of preventing critical damage to the entire system200even when power is cut off while the sphere210is being levitated and rotates in the operation mode.

In the sphere magnetic levitation system200according to the present invention, the electromagnet control unit240and the solenoid valve control unit250may use common power, and power-off means that power is not supplied to either the electromagnet control unit240or the solenoid valve control unit250. In this case, power is not supplied to the electromagnets220, and the magnetic field generated by the electromagnets220is eliminated, and accordingly the levitated sphere210goes back to an original position thereof. Here, in the solenoid valve control unit250, power is not supplied to the solenoid valve420, and the magnetic field501generated by the electromagnetic coil423is eliminated. Accordingly, the plunger422pushes up the ball cup414again by the restoring force of the spring424. In the case of power-off, as in the above described method, the main ball411provided at the upper portion of the ball cup414comes into direct contact with the sphere210, physically supporting the sphere210, and thereby the entire system200is not affected.

As shown inFIGS. 4 to 6, the embodiment of the present invention supposes that when power is not supplied to the electromagnetic coil423, the spring is released, and on the contrary, when power is supplied to the electromagnetic coil, the spring is compressed; however, the reverse is possible in other embodiments.

In the above description, the sphere magnetic levitation system according to the present invention is used as an attitude control actuator for a satellite. However, the sphere magnetic levitation system can be used as a three-dimensional centrifuge if using a function of generating momentum and torque. Further, the sphere magnetic levitation system can be applied to an actuator for changing a direction and stabilizing attitude of a moving object, such as a satellite, a ship, an aircraft, a motor vehicle, a submarine, and the like.

DESCRIPTION OF REFERENCE CHARACTERS OF IMPORTANT PARTS

240: electromagnet control unit

250: solenoid valve control unit