Six degree of freedom control of planar motors
First Claim
1. A method for controlling a planar electric motor comprising a magnet array having a magnets with magnetic fields and a coil array comprising coils generally disposed in a plane, for positioning in six degrees of freedom, comprising:
- determining currents to be applied to coils to generate forces between the magnet array and the coil array in first, second, and third directions, the first and second directions lying in the plane and being generally orthogonal to each other and the third direction being generally orthogonal to the first and second directions;
determining resultant torques about the first, second, and third directions between the magnet array and the coil array generated by the forces generated by the determined currents;
determining current adjustments to compensate for the resultant torques; and
applying a sum of the determined currents and determined current adjustments to the coils to interact with the magnetic fields of the magnet array to control the planar electric motor.
1 Assignment
0 Petitions
Accused Products
Abstract
A method for controlling and positioning a two-dimensional electric motor in six degrees of freedom is disclosed. The electric motor has a coil array and a magnet array. The method controls the motor in six degrees of freedom. The method includes: determining currents for generating the desired forces in a first, second and third direction, the first and second directions being defined in a plane in which the magnets are disposed and the third direction being generally orthogonal to the first and second directions, determining a resultant torque about the first, second, and third directions that would be generated from applying the determined currents, determining current adjustments to compensate for the resultant torque, and applying a current equal to the sum of the determined currents and the current adjustments to the coils to interact with the magnetic fields of the magnet array. The currents are applied only to the portion of the coil array within the magnetic field of the magnet array, including those coils which are only partially within the magnetic field of the magnet array. The method of the invention may be used in applications such as positioning wafers in semiconductor fabrication.
28 Citations
42 Claims
-
1. A method for controlling a planar electric motor comprising a magnet array having a magnets with magnetic fields and a coil array comprising coils generally disposed in a plane, for positioning in six degrees of freedom, comprising:
-
determining currents to be applied to coils to generate forces between the magnet array and the coil array in first, second, and third directions, the first and second directions lying in the plane and being generally orthogonal to each other and the third direction being generally orthogonal to the first and second directions;
determining resultant torques about the first, second, and third directions between the magnet array and the coil array generated by the forces generated by the determined currents;
determining current adjustments to compensate for the resultant torques; and
applying a sum of the determined currents and determined current adjustments to the coils to interact with the magnetic fields of the magnet array to control the planar electric motor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
-
-
12. A method for determining current to be applied to control a planar electric motor in six degrees of freedom, the motor having a magnet array and a coil array having coils generally disposed in a plane, comprising:
-
determining currents to be applied to coils to generate forces between the magnet array and the coil array in first, second, and third directions, the first and second directions lying in the plane and being generally orthogonal to each other and the third direction being generally orthogonal to the first and second directions, the currents being dependent upon the position of the magnet array and desired forces in the first, second, and third directions or about the first, second, and third directions;
determining resultant torques generated by the determined currents; and
determining current adjustments to be added to the determined currents to compensate for the resultant torques. - View Dependent Claims (13, 14, 15, 16, 17)
-
-
18. A method for positioning an object in a lithography system, comprising:
-
providing a frame;
providing a stage for supporting the object and movable to position the object relative to the frame in six degrees of freedom;
providing a coil array attached to the frame, the coil array having coils;
providing a magnet array adjacent a portion of the coil array, the magnet array being attached to the stage and having magnets generally disposed in a plane, the plane defining a first and second direction;
determining currents to be applied to coils in the portion of the coil array to generate forces between the magnet array and the coil array in the first, second, and third directions;
determining a resultant torque between the magnet array and the coil array generated by the forces;
determining current adjustments to compensate for the resultant torque; and
applying a sum of the determined currents and determined current adjustments to the coils to interact with magnetic fields of the magnet array. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 30, 31)
-
-
29. A method for determining current to be applied to control a planar electric motor in six degrees of freedom, the motor having a magnet array and a coil array having coils generally disposed in a plane, comprising:
-
determining a position of the magnet array relative to the coil array in the X, Y, and Z directions, the X and Y directions being defined by the plane and the Z direction being generally orthogonal to the X and Y directions;
determining desired forces Rx, Ry, and Rz in the X, Y, and Z directions, respectively, for independently controlling the magnet array to move relative to the coil array in the X, Y, and Z directions or about the X, Y, and Z directions;
determining currents to be applied to the coils for generating the desired forces Rx, Ry, and Rz between the magnet array and the coil array;
determining a resultant torque generated by the currents according to the position of the magnet array relative to the coil array and to the desired forces Rx, Ry, and Rz; and
determining current corrections Δ
x, Δ
y, Δ
z to be added to the currents, to produce torques Tx, Ty, Tz;
wherein resultant the forces Fx, Fy, Fz are equal to the desired forces Rx, Ry, and Rz, and the resultant torques Tx, Ty, Tz equal desired values.
-
-
32. A planar motor comprising:
-
a first member;
a second member that interacts with the first member to generate driving force, the second member being movable relative to the first member in six degrees of freedom including a first, second, and third directions by the driving force; and
a controller connected to at least one of the first member and second member, the controller determining information related to resultant torque about the first, second and third directions between the first member and the second member generated by the driving force. - View Dependent Claims (33, 36, 37, 38, 39, 40, 41, 42)
-
- 34. The planar motor of clam 32, wherein the controller determines the information that is utilized to compensate for the resultant torque.
Specification