Methods and systems for controllably moving multiple moveable stages in a displacement device

Patent metadata

Field	Value
Publication number	US-10056816-B2
Application number	US-201615370987-A
Country	US
Kind code	B2
Filing date	Dec 6, 2016
Priority date	Jun 7, 2014
Publication date	Aug 21, 2018
Grant date	Aug 21, 2018

Abstract

Aspects of the invention provide methods and systems for moving a plurality of movable stages relative to a stator. The stator comprises a plurality of coils shaped to provide pluralities of coil trace groups where each coil trace group comprises a corresponding plurality of generally linearly elongated coil traces which extend across a stator tile. Each movable stage comprises a plurality of magnet arrays. Methods and apparatus are provided for moving the movable stages relative to the stator, where a magnet array from a first movable stage and a magnet array from a second movable stage both overlap a shared group of coil traces. For at least a portion of the time that the magnet arrays from the first and second movable stages overlap the shared group of coil traces, currents are controllably driven in the shared coil trace group based on the positions of both the first and second movable stages. The positions of the first and second movable stages may be ascertained by feedback.

First claim

What is claimed is:

1. A method for moving a plurality of moveable stages relative to a stator, the method comprising:
providing a stator comprising one or more stator tiles, each stator tile comprising:
an x-trace layer comprising a plurality of x-trace groups, each x-trace group comprising a plurality of electrically conductive x-traces which extend in a stator-x direction across the stator tile and into which currents may be independently driven;
a y-trace layer comprising a plurality of y-trace groups, each y-trace group comprising a plurality of electrically conductive y-traces which extend in a stator-y direction across the stator tile and into which currents may be independently driven;
the x-trace layer and the y-trace layer overlapping one another in a stator-z direction;
the stator-x direction and the stator-y direction non-parallel to one another;

providing a plurality of moveable stages, each moveable stage comprising:
a first magnet array comprising a plurality of first magnetization segments, each first magnetization segment having a corresponding magnetization direction; and

driving currents in the x-traces and the y-traces to move a first moveable stage and a second moveable stage relative to the stator where the first magnet array of the first moveable stage overlaps with the first magnet array of the second moveable stage in the stator-x direction, wherein driving currents in the x-traces and the y-traces to move the first moveable stage and the second moveable stage relative to the stator comprises:
for at least a first portion of a time where the first magnet array of the first moveable stage overlaps with the first magnet array of the second moveable stage in the stator-x direction, controllably driving first x-trace group currents in a first x-trace group that overlaps with a first portion of the first magnet array of the first moveable stage in the stator-z direction and a first portion of the first magnet array of the second moveable stage in the stator-z direction, the first x-trace group currents determined based at least in part on positions of both the first moveable stage and the second moveable stage and the first x-trace group currents generating first forces on the first magnet array of the first moveable stage and on the first magnet array of the second moveable stage.

2. A method according to claim 1 wherein each first magnetization segment is linearly elongated in a stage-x direction, and the magnetization direction of each first magnetization segment is orthogonal to the stage-x direction and at least two of the first magnetization segments having magnetization directions that are different from one another.

3. A method according to claim 2 wherein driving currents in the x-traces and the y-traces to move the first moveable stage and the second moveable stage relative to the stator comprises:
for at least the first portion of the time where the first magnet array of the first moveable stage overlaps with the first magnet array of the second moveable stage in the stator-x direction, controllably driving second x-trace group currents in a second x-trace group that overlaps with a second portion of the first magnet array of the first moveable stage in the stator-z direction and a second portion of the first magnet array of the second moveable stage in the stator-z direction, the second x-trace group currents determined based at least in part on positions of both the first moveable stage and the second moveable stage and the second x-trace group currents generating second forces on the first magnet array of the first moveable stage and on the first magnet array of the second moveable stage.

4. A method according to claim 3 wherein driving currents in the x-traces and the y-traces to move the first moveable stage and the second moveable stage relative to the stator comprises:
for at least a second portion of the time where the first magnet array of the first moveable stage overlaps with the first magnet array of the second moveable stage in the stator-x direction, refraining from driving currents in the first x-trace group; and
for at least the second portion of the time where the first magnet array of the first moveable stage overlaps with the first magnet array of the second moveable stage in the stator-x direction, refraining from driving currents in the second x-trace group.

5. A method according to claim 3 wherein driving currents in the x-traces and the y-traces to move the first moveable stage and the second moveable stage relative to the stator comprises:
for at least a second portion of the time where the first magnet array of the first moveable stage overlaps with the first magnet array of the second moveable stage in the stator-x direction, driving currents in the first x-trace group and the second x-trace group which are the same as one another.

6. A method according to claim 3 wherein each moveable stage comprises a third magnet array comprising a plurality of third magnetization segments linearly elongated in the stage-x direction, each third magnetization segment having a corresponding magnetization direction orthogonal to the stage-x direction and at least two of the third magnetization segments having magnetization directions that are different from one another.

7. A method according to claim 6 wherein each moveable stage comprises a second magnet array comprising a plurality of second magnetization segments linearly elongated in a stage-y direction, each second magnetization segment having a magnetization direction orthogonal to the stage-y direction and at least two of the second magnetization segments having magnetization directions that are different from one another; and wherein the stage-x direction and the stage-y direction non-parallel to one another.

8. A method according to claim 7 wherein driving currents in the x-traces and the y-traces to move the first moveable stage and the second moveable stage relative to the stator comprises, during the first portion of the time where the first magnet array of the first moveable stage overlaps with the first magnet array of the second moveable stage in the stator-x direction, driving currents in the x-traces and the y-traces which control motion of the first moveable stage with six degrees of freedom and which control motion of the second moveable stage with six degrees of freedom.

9. A method according to claim 7 wherein driving currents in the x-traces and the y-traces to move the first moveable stage and the second moveable stage relative to the stator where the first magnet array of the first moveable stage overlaps with the first magnet array of the second moveable stage in the stator-x direction comprises:
controllably driving first y-trace group currents in a first y-trace group that overlaps with the second magnet array of the first moveable stage in the stator-z direction, the first y-trace group currents determined based on the position of the first moveable stage and independent of the position of the second moveable stage;
controllably driving second y-trace group currents in a second y-trace group that overlaps with the second magnet array of the second moveable stage in the stator-z direction, the second y-trace group currents determined based on the position of the second moveable stage and independent of the position of the first moveable stage.

10. A method according to claim 9 wherein each moveable stage comprises a fourth magnet array comprising a plurality of fourth magnetization segments linearly elongated in the stage-y direction, each fourth magnetization segment having a magnetization direction orthogonal to the stage-y direction and at least two of the fourth magnetization segments

Assignees

• Univ British Columbia

Inventors

• Lu Xiaodong

Classifications

• H02N15/00

  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}) · CPC title

• H02K16/02

  Machines with one stator and two {or more} rotors · CPC title

• H02P8/00

  Arrangements for controlling dynamo-electric motors rotating step by step · CPC title

• H02P25/066

  of the stepping type · CPC title

• H02K41/02

  Linear motors; Sectional motors · CPC title