Flat-coil actuator having coil embedded in linkage

• US 6,437,770 B1
• Filed: 01/25/1999
• Issued: 08/20/2002
• Est. Priority Date: 01/26/1998
• Status: Expired due to Fees

• Current Assignee: University of Washington, Washington University In St Louis
• Original Assignee: University of Washington
• Inventors: Venema, Steven, Hannaford, Blake
• Primary Examiner(s): WU, XIAO MIN
• Application Number:
  US09/237,138
• Time in Patent Office: 1,303 Days
• Field of Search: 345/156, 345/157, 345/161, 345/162, 345/163, 345/164, 345/165, 345/166, 345/167, 345/168, 345/173, 345/179, 33/1.M, 744/71.XY
• US Class Current: 345/156
• CPC Class Codes: G06F 3/011 Arrangements for interaction with the human body, e.g. for user immersion in virtual reality blind teaching G09B21/00
• CPC Class Codes: H01F 7/066 Electromagnets with movable winding
• CPC Class Codes: H01F 7/122 by permanent magnets H01F7/1615, H01F7/1646 take precedence
• CPC Class Codes: H01F 7/14 Pivoting armatures H01F7/17 takes precedence
• CPC Class Codes: H01F 7/1615 Armatures or stationary parts of magnetic circuit having permanent magnet

Abstract

A flat-coil actuator embedded in a linkage of a mechanical interface for a force feedback device. The linkage rotates about an axis, where a flat coil is embedded in the linkage between two ends or connection points of the linkage. Magnets are positioned parallel to the flat coil, where a force is produced on the linkage when a current is flowed in the coil. An embedded position sensor, such as an optical encoder, can be coupled to the linkage. A force feedback device incorporating the flat-coil actuator includes a user manpulandum, where the linkage is coupled between a ground and the user manipulandum. Other linkages can also be coupled to the actuator to provide mechanisms such as a five-bar linkage mechanism.

Claims

1. A flat-coil actuator comprising:

a linkage operative to rotate about an axis, said linkage having two connection points, wherein one of said connection points is coupled to a ground;

a flat coil embedded in said linkage, said flat coil being positioned between said connection points; and

a plurality of magnets positioned approximately parallel to said flat coil and grounded with respect to said linkage, wherein a first one or more magnets is positioned on a first side of said flat coil, and wherein a second one or more magnets is positioned on a second side of said flat coil such that said coil is oriented in a plane positioned between a plane of said first magnets and a plane of said second magnets, wherein a force is produced on said linkage when a current is flowed in said flat coil.

2. A flat-coil actuator as recited in claim 1 further comprising an embedded position sensor coupled to said linkage.

3. A flat-coil actuator as recited in claim 2 wherein said sensor includes at least a portion of a code disk coupled to said linkage at said axis and an emitter/detector for detecting motion of said portion of said code disk.

4. A flat-coil transducer as recited in claim 1 wherein said linkage is rotatably coupled to a ground at one of said connection points and to another linkage at the other of said connection points.

5. A flat-coil transducer as recited in claim 1 wherein said flat coil surrounds a core that adds mechanical strength to said linkage.

6. A flat-coil transducer as recited in claim 1 wherein each of said magnets is coupled to a backing iron.

7. A flat-coil transducer as recited in claim 1 wherein said linkage is coupled to a user manipulandum physically contacted by a user.

8. A force feedback interface device including an improved flat-coil actuator, the force feedback interface device comprising:

a flat-coil actuator including;

a linkage operative to rotate about an axis and having two connection points;

a flat coil embedded in said linkage, said flat coil being positioned between said two connection points of said linkage; and

a plurality of magnets positioned approximately parallel to said flat coil and grounded with respect to said linkage, wherein a force is produced on said linkage when a current is flowed in said flat coil;

a sensor coupled to said linkage for detecting motion of said linkage about said axis; and

a user manipulandum graspable by a user and coupled to one of said connection point of said linkage such that said force is transmitted to said user manipulandum.

9. A force feedback interface device as recited in claim 8 wherein one of said connection points of said linkage is coupled to a ground, and the other of said connection points is coupled to said user manipulandum.

10. A force feedback interface device as recited in claim 8 further comprising an intermediate linkage coupled between said linkage and said user manipulandum.

11. A force feedback interface device as recited in claim 10 wherein said flat-coil actuator is a first flat-coil actuator, and further comprising a second flat-coil actuator, wherein said user manipulandum is coupled to both said first and second flat-coil actuators.

12. A force feedback interface device as recited in claim 11 wherein said intermediate linkage is a first intermediate linkage, and further comprising a second intermediate linkage coupled between said second flat-coil actuator and said user manipulandum, wherein said first and second intermediate linkages are rotatably coupled to each other.

13. A force feedback interface device as recited in claim 12 wherein said flat-coil actuators and said intermediate linkages form a closed-loop five-bar linkage mechanism having linkages rotatably coupled to each other.

14. A force feedback interface device as recited in claim 8 wherein said flat coil is embedded in said end of said linkage such that a portion of said linkage entirely surrounds said coil in a plane perpendicular to said axis.

15. A force feedback interface device as recited in claim 8 wherein said sensor is an optical encoder including a code disk coupled to said linkage at said axis and a emitter/detector for detecting motion of said code disk.

16. A force feedback interface device as recited in claim 15 wherein said code disk is positioned between an emitter and a detector of said emitter/detector.

17. A method for using an actuator to provide force feedback to a user of a force feedback device, the method comprising:

flowing a current through a planar coil of a flat-coil actuator included in said force feedback device, said coil positioned between first and second connection points of a member;

rotating said member about an axis using said current and a magnetic field from at least one magnet positioned adjacent to said coil, wherein said rotation outputs a force at said second connection point of said member, wherein said force is output to a user manipulandum coupled to said second connection point of said member; and

sensing said rotation of said member with an encoder and outputting a sensor signal representative of said rotation of said member.

18. A method as recited in claim 17 wherein said encoder includes a code disk coupled to said rotor at said axis and an emitter/detector for detecting motion of said code disk, wherein said code disk is positioned between an emitter and a detector of said emitter/detector.

19. A method as recited in claim 17 wherein said sensor signal is output to a host computer including a display screen, wherein images displayed on said display screen are updated at least in part based on said sensor signal.

20. A method as recited in claim 17 wherein said sensor signal is output to a host computer displaying a graphical environment, wherein images displayed in said graphical environment are updated based at least in part on said sensor signal, and wherein said host computer outputs a force feedback signal to said force feedback device, wherein said force output to said user manipulandum is based at least in part on said force feedback signal.