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1. (EP1332946) Hand wheel actuator
Nota: O texto foi obtido por processos automáticos de reconhecimento ótico de caracteres.
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Claims

1. A hand wheel actuator (10) for providing force feedback to a user, the actuator comprising:

a steering shaft fixed to said hand wheel (12) and supported by bearings such that is rotatable about its own axis;

a position sensor detecting an angular displacement of said steering shaft from a selected origin and producing a signal indicative of said angular displacement;

an electric motor (40, 185);

a transmission (45) means operatively connecting an output shaft (41) of said electric motor (40, 185) to said steering shaft; and

a variable stopper (70) stopping rotation of said steering shaft at an arbitrary location.


  2. The hand wheel actuator (10) of claim 1, said variable stopper (70) comprising a magnetic rheological fluid (80) device operatively connected to said steering shaft.
  3. The hand wheel actuator (10) of claim 2, wherein said magnetic rheological fluid (80) device is positioned on said output shaft (41) of said electric motor (40, 185).
  4. The hand wheel actuator (10) of claim 1 further comprising a spring-biased mechanical return-to-center device (90) for providing resistance against turning said steering shaft away from said central position, said mechanical return-to-center device (90) being operatively connected to said steering shaft.
  5. The hand wheel actuator (10) of claim 4 wherein said mechanical return-to-center device (90) comprises a ball screw (54) fixed to said steering shaft; a ball nut (58) engaging said ball screw (54), said ball nut (58) constrained to travel linear along an axis of said ball screw (54), and a compression spring positioned around an extension (64) of said ball nut (58), said extension (64) and a housing (30) cooperating to cause said compression spring to compress with increased angular displacement from said central location.
  6. The hand wheel actuator (10) of claim 4, said variable stopper (70) (70) comprising a magnetic rheological fluid (80) device positioned on said output shaft (41) of said electric motor (40, 185).
  7. The hand wheel actuator (10) of claim 1 further comprising an positive travel end stopper (50) limiting angular displacement of said steering shaft to a selected limit.
  8. The hand wheel actuator (10) of claim 7 wherein said selected limit is !540°.
  9. The hand wheel actuator (10) of claim 7 wherein said positive travel end stopper (50) comprises a ball screw (54) operatively connected to said steering shaft, a ball nut (58) engaged to said ball screw (54), said ball nut (58) comprising at least one locator extending transversely from an axis of said ball screw (54), said locator extending into a slot (56, 160) of a selected length formed in a housing (30) positioned around said ball screw (54), said slot (56, 160) and said locator cooperating to constrain movement of said ball nut (58), thereby limiting said angular displacement.
  10. The hand wheel actuator (10) of claim 9 further comprising a spring-biased mechanical return-to-center device (90) providing resistance against turning said steering shaft away from said central position, said mechanical return-to-center device (90) comprising a compression spring positioned around an extension (64) of said ball nut (58), said extension (64) and a housing (30) (30) cooperating to cause said compression spring to compress with increased angular displacement from said central location.
  11. The hand wheel actuator (10) of claim 7 wherein said positive travel end stopper (50) comprises a pinion (151) operatively connected to said steering shaft and a gear (153) engaged to said pinion (151), said gear (153) having at least one stop tooth (154), for preventing said gear (153) from making one full rotation, said pinion (151) and said gear (153) being sized to limit said angular displacement to said selected limit.
  12. The hand wheel actuator (10) of claim 11 wherein said selected limit is !540°.
  13. The hand wheel actuator (10) of claim 1 wherein said variable stopper (70) comprises
a ball screw (54) operatively connected to said steering shaft;
a ball nut (58) engaged on said ball screw (54), said ball nut (58) being constrained to travel linearly;
a ball nut (58) locator extending from said ball nut (58);
a variable stop locator positioned to engage said ball nut (58) locator at a desired limit of angular displacement, said variable stop locator having a first surface (173) that interacts with said ball nut (58) locator at a first limit of said angular displacement and a second surface (175) that interacts with said ball nut (58) locator at a second limit of said angular displacement, said ball nut (58) locator being free to move between said first and second limits in response to rotation of said steering shaft;
an actuator for repositioning said variable stop locator.
  14. The hand wheel actuator (10) of claim 13 wherein said actuator comprises a second motor (40, 185) connected at its output shaft (41) to a second ball screw (54), said variable stop locator being fixed to a second ball nut (58) that engages said second ball screw (54).
  15. The hand wheel actuator (10) of claim 13 further comprising a housing (30) extended around said ball nut (58) and said ball screw (54), said housing (30) having at least one slot (56, 160) formed longitudinally in said housing (30), said ball nut (58) locator extending into said slot (56, 160), said slot (56, 160) limiting rotational movement of said ball nut (58) when said ball screw (54) is rotated, thereby causing said ball nut (58) to move linearly.
  16. The hand wheel actuator (10) of claim 15 wherein said variable stop locator is partially positioned in one of said at least one slot (56, 160), thereby defining limits of linear movement of said ball nut (58), thus limiting rotational movement of said ball screw (54) and said steering shaft.
  17. The hand wheel actuator (10) of claim 14 wherein said variable stop locator is formed of a cylinder extending around said ball nut (58) and said ball screw (54), said cylinder having at least one slot (56, 160) formed therein, said slot (56, 160) limiting rotational movement of said ball nut (58) when said ball screw (54) is rotated, a length of said slot (56, 160) defining limits of linear movement of said ball nut (58), thus limiting rotational movement of said ball screw (54) and said steering shaft.
  18. The hand wheel actuator (10) of claim 17 wherein said second ball screw (54) is oriented in parallel with said steering shaft, said hand wheel actuator (10) further comprising a support structure fixing and connecting said variable stop locator with said second ball nut (58).
  19. The hand wheel actuator (10) of claim 17 wherein said second ball screw (54) is not oriented in parallel with said steering shaft, said hand wheel actuator (10) further comprising a mechanical link extending from said second ball nut (58) to said variable stop locator, said link operating to translate linear motion of said second ball nut (58) along an axis of said second ball screw (54) to linear motion of said variable stop locator along an axis of said steering shaft.
  20. The hand wheel actuator (10) of claim 13 wherein said actuator comprises a second motor (40, 185) connected at its output end to a pinion (151), said variable stop locator being fixed to a rack (274) and being constrained to move linearly along a support shaft that is parallel with said ball screw (54), said pinion (151) and said rack (274) being in engagement such that when said pinion (151) is turned by said motor (40, 185), said rack (274) and variable stop locator moves linearly parallel with said ball screw (54).
  21. The hand wheel actuator (10) of claim 13 wherein said variable stop locator is fixed to an output shaft (41) of a rotary actuator, said output shaft (41) of said rotary actuator being disposed transverse to an axis of said ball screw (54); when actuated, on of said first and second surface (175) being in position that defines said limit of said angular displacement of said steering shaft.
  22. The hand wheel actuator (10) of claim 1, said variable stopper (70) comprising a pinion (151) operatively connected to said steering shaft, a gear (153) engaged with said pinion (151), said gear (153) and said pinion (151) being sized such that said gear (153) makes less than one complete revolution when said steering shaft is turned from its left most limit to its right most limit, said gear (153) having a slot (56, 160), said slot (56, 160) extending circumferentially from a start point to a stop point, said start point and said stop point corresponding to said left most limit and said right most limit of rotation of said steering shaft; said variable stop locator comprising a peg extending into said slot (56, 160), said peg being mounted to an arm (214) that is fixed to an output shaft (41) of a stopper motor positioned coaxially with said gear (153), whereby actuation of said motor (40, 185) repositions said peg thereby redefining said left most limit and said right most limit of rotation of said steering shaft.
  23. The hand wheel actuator (10) of claim 1 wherein said variable stopper (70) comprises:

a ratchet assembly having a first set of teeth facing clockwise and a second set of teeth facing counter-clockwise;

a first and second pawl fixed to the output shaft (41) of at least one actuator, said first pawl being aligned with said first set of teeth, and said second pawl being aligned with said second set of teeth, said first set of teeth and said second set of teeth and said first pawl and said second pawl cooperating such that when said first pawl engages said first set of teeth, said steering shaft is prevented from rotating clockwise, and when said second pawl engages said second set of teeth, said steering shaft is prevented from rotating counter-clockwise.