Control system for a magnetic levitation body

• US 5,093,754 A
• Filed: 10/13/1989
• Issued: 03/03/1992
• Est. Priority Date: 10/18/1988
• Status: Expired due to Term

• Current Assignee: Edwards Japan Limited (Atlas Copco AB)
• Original Assignee: Seiko Seiki Kabushiki Kaisha
• Inventors: Kawashima, Toshiaki
• Primary Examiner(s): Pellinen, A. D.
• Assistant Examiner(s): Gaffin, Jeffrey A.
• Application Number:
  US07/421,179
• Time in Patent Office: 872 Days
• Field of Search: 361/139, 361/143, 361/144, 361/146, 361/147, 307/104, 310/90.5
• US Class Current: 361/144
• CPC Class Codes: B60L 13/06 Means to sense or control vehicle position or attitude with respect to railway
• CPC Class Codes: F16C 2231/00 Running-in; Initial operation
• CPC Class Codes: F16C 2326/10 Railway vehicles
• CPC Class Codes: F16C 2360/44 Centrifugal pumps
• CPC Class Codes: F16C 2360/45 Turbo-molecular pumps
• CPC Class Codes: F16C 32/0442 with devices affected by abnormal, undesired or non-standard conditions such as shock-load, power outage, start-up or touchdown
• CPC Class Codes: F16C 32/0451 Details of controllers, i.e. the units determining the power to be supplied, e.g. comparing elements, feedback arrangements with P.I.D. control
• CPC Class Codes: H02N 15/00 Holding or levitation devices using magnetic attraction or repulsion, not otherwise provided for electric or magnetic devices for holding work on machine tools B23Q3/15 ; monorail vehicle propulsion or suspension B60L13/00; sliding or levitation devices for railway systems B61B13/08; material handling devices associated with conveyors incorporating devices with electrostatic or magnetic grippers B65G47/92; separating thin or filamentary articles from piles using magnetic force B65H3/16; delivering thin or filamentary articles from magnetic holders by air blast or suction B65H29/24; bearings using magnetic or electric supporting means F16C32/04; relieving bearing loads using magnetic means F16C39/06; magnets H01F7/00; dynamo-electric clutches or brakes H02K49/00 ; electric furnaces with simultaneous levitation and heating H05B6/32

Abstract

A method for controlling an initial position of a magnetically levitated body comprises sensing the position of the levitated body by position sensors and applying exciting currents to electromagnets in response to the sensed position to adjust the position of the body to an initial central position. The sensing step comprises detecting a first limiting position of the body in a first direction and detecting a second limiting position of the body in a second direction opposite the first direction. The applying step comprises calculating a central position from the first and second limiting positions and applying exciting currents to the electromagnets to move the body into the calculated central position. An apparatus for controlling positioning of a magnetically levitated body based on limiting positions is also disclosed.

Claims

1. A control system for a magnetic levitation body, comprising:

a magnetic levitation body which is held afloat by electromagnets;

position sensors for detecting a levitating position of said magnetic levitation body; and

control means for outputting an exciting current to said electromagnets upon inputting a detection signal detected by said position sensors and making an adjustment of the exciting current of said electromagnets to hold said magnetic levitation body afloat in a predetermined position, said control means including a detecting circuit for detecting a limit position in a movable range of said magnetic levitation body, and a correction circuit for correcting a target levitating position of said magnetic levitation body by computing a central levitating position from said limit position detected by said detecting circuit.

2. A method for controlling the position of a magnetically levitated body comprising the steps of:

sensing the position of a levitated body by position sensors; and

applying exciting currents to electromagnets in response to the sensed position by the position sensors to adjust the position of the body to a calculated central position;

wherein the sensing step comprises detecting a first limiting position of the body in a first direction and detecting a second limiting position of the body in a second direction opposite the first direction, and the step of applying exciting currents to adjust the position comprises calculating a central position from the first and second limiting positions and applying exciting currents to the electromagnets to move the body into the calculated central position.

3. The method according to claim 2, wherein the step of calculating comprises storing the first and second limiting positions and calculating the central position from the stored limiting positions.

4. The method according to claim 2, further comprising calculating the sensitivity of the sensors from the difference between the limiting positions and adjusting the gain between the sensors and the electromagnets in accordance therewith.

5. The method according to claim 2, wherein the step of detecting the first and second limiting positions includes moving the body to said first limiting position, sensing the position and storing the sensed position as the first limiting position;

and moving the body to the second limiting position, sensing the position and storing the sensed position as the second limiting position.

6. A system for controlling the position of a magnetically levitated body comprising:

means for sensing position of a levitated body;

electromagnets for maintaining a position of the body in response to exciting currents applied thereto; and

means for adjusting the position of the body in response to the sensed position to adjust the position of the body to a calculated central position, wherein the means for sensing comprises means for detecting a first limiting position of the body in a first direction and means for detecting a second limiting position of the body in a second direction opposite the first direction, and wherein the means for adjusting the position comprises means for calculating a central position from the first and second limiting position and means for applying exciting currents to the electromagnets to move the body into the calculated central position.

7. The method according to claim 6, wherein the means for calculating comprises means for storing the first and second limiting positions and means for calculating the central position from the stored limiting positions.

8. The method according to claim 6, further comprising means for calculating the sensitivity of the sensors from the difference between the limiting positions, and means for adjusting the gain between the sensors and the electromagnets in accordance with the sensitivity.