Electromagnetic method of the angular displacement monitoring

• US 6,393,912 B2
• Filed: 08/24/1999
• Issued: 05/28/2002
• Est. Priority Date: 08/14/1998
• Status: Expired due to Term

• Current Assignee: MTS Systems Corporation (Illinois Tool Works Inc.)
• Original Assignee: MTS Systems Corporation (Illinois Tool Works Inc.)
• Inventors: Nyce, David S., Pchelnikov, Yuriy N.
• Primary Examiner(s): MOLLER, RICHARD ALAN
• Application Number:
  US09/379,840
• Publication Number:
  US 20010042406A1
• Time in Patent Office: 1,008 Days
• Field of Search: 73/488,504.01 324/160,166,167,207.11,207.13,207.14,207.15,207.16,207.25
• US Class Current: 73/488
• CPC Class Codes: G01F 23/284 Electromagnetic waves

Abstract

A method and apparatus is disclosed for monitoring an angular displacement, such as angle position and the direction of displacement. The method and apparatus includes at least one resonator placed in proximity to a electrodynamic profile and exciting within said resonator an alternating electromagnetic field. The electromagnetic field should be at a frequency at which the electromagnetic field contacts the electrodynamic profile and then variations of the electromagnetic field parameters are measured for the resonator caused by rotating the electrodynamic profile. Excitation of the resonator is by an electromagnetic field in the form of at least one slowed electromagnetic wave having a suitable energy distribution of the electric and magnetic fields for measuring the electromagnetic field parameters.

Claims

1. A method for monitoring an angular displacement in a rotation plane about a rotation axis and related displacement parameters of a moving part, comprising:

mounting at least one electrodynamic profile on the moving part;

placing at least one resonator in proximity to said electrodynamic profile;

exciting in said resonator an alternating electromagnetic field at a frequency at which the electromagnetic field penetrates into the electrodynamic profile;

measuring the variation of the electromagnetic field parameters, caused by displacement of the electrodynamic profile,

said exciting of said resonator is by an electromagnetic field in the form of at least one slowed electromagnetic wave having energy distribution of the electric and magnetic fields in said electrodynamic profile suitable for the maximum influence of its movement; and

measuring of variation of the slowed electromagnetic wave parameters, and comparing said measured parameters.

2. The method of claim 1, wherein:

the scalar angular displacement is measured.

3. The method according to claim 2, wherein:

the scalar angular displacement exceeds 180°

.

4. The method according to claim 2, wherein:

the scalar measured angular displacement is continuous.

5. A method of claim 1, wherein said measuring step includes measuring of variation of the slowed electromagnetic wave parameters.

6. A method of claim 5, wherein said measuring step includes measured parameters.

7. The method according to claim 6, wherein:

at least two said resonators are placed in the rotation plane at the same distance from and diametrically opposed to the rotation axis, and

parameters of at least two slowed electromagnetic waves are measured and compared.

8. The method according to claim 6, wherein:

there is included the step of converting results of said comparing into a representation of the angular displacement parameters.

9. The method according to claim 6, wherein:

the angular displacement and its direction are monitored.

10. The method according claim 9, wherein:

at least two resonators are placed with an angle shift in the rotation plane at the same distance from said electrodynamic profile, and

parameters of at least two said slowed electromagnetic waves are measured and compared.

11. The method according to claim 10, wherein:

said angular shift is equal to approximately 90°

.

12. The method according to claim 10, wherein:

at least two said resonators are placed in the rotation plane at the same distance from and diametrically opposed to the rotation axis.

13. The method according to claim 9, wherein:

at least four said resonators are placed with 90°

angular shift in the rotation plane at the same distance from said electrodynamic profile, and

the slowed electromagnetic waves are excited in each of said resonators,

the parameters of said slowed waves in each resonator are measured and compared.

14. The method according to claim 1, wherein:

said slowed electromagnetic wave is an in-phase type of wave.

15. The method according to claim 1, wherein:

said slowed electromagnetic wave is an anti-phase type of wave.

16. The method according to claim 1, wherein:

the one slowed electromagnetic wave is an anti-phase type of wave, the other is an in-phase type of wave.

17. The method according to claim 1, wherein:

the electric field of said slowed electromagnetic wave is presented nearby the electrodynamic profile by the zero space harmonic.

18. The method according to claim 1, wherein:

the magnetic field of said slowed electromagnetic wave is presented nearby said electrodynamic profile by the zero space harmonic.

19. The method according to claim 1, wherein:

the electric field of the slowed electromagnetic wave is presented nearby the electrodynamic profile by the plus one, minus one space harmonics.

20. The method according to claim 1, wherein:

the magnetic field of the slowed electromagnetic wave is presented nearby the electrodynamic profile by the plus one, minus one space harmonics.

21. A method according to claim 1, wherein said slowed electromagnetic wave has an energy distribution of the electric and magnetic fields in said electrodynamic profile suitable for the maximum influence of its movements.

22. An apparatus for monitoring angular displacement in a rotation plane about a rotation axis of a moving part, comprising:

at least one electrodynamic profile 1 for electric and magnetic fields mounted on the moving part 2 the displacement of the part 2 which is to be monitored,

at least one resonator 4, including at least one matching plug 5, and a measuring circuit 6, including at least one radio frequency generator 7, at least one primary transducer 8 and a converter 9 converting and comparing electric signals into the parameter of angular displacement,

said resonator including at least one section of a sensitive slow-wave structure set to distribute in a given ratio the components of an electric and magnetic fields in the electrodynamic profile, and connected to said matching plug;

said sensitive slow-wave structure further including at least two conductors, at least one of said conductors being an impedance conductor facing said electrodynamic profile.

23. The apparatus according to claim 22, wherein:

said slow-wave structure is fashioned as a row of conducting members arranged in series in the direction of the slowed wave propagation and connected to one another with spacing.

24. The apparatus according to claim 22, wherein:

said slow-wave structure forming a quadripole multi-pole.

25. An apparatus of claim 22, wherein said resonator includes at least one matching plug.

26. An apparatus of claim 25, wherein said section of a sensitive slow-wave structure is connected to said matching plug.

27. The apparatus according to claim 25, wherein:

said slow-wave structure forming a multi-pole.

28. The apparatus according to claim 27, wherein:

both ends of said multi-pole are connected one to another, said multi-pole forming a traveling wave resonator.

29. The apparatus according to claim 28, wherein:

said resonator is connected to the measuring circuit through one of said matching plugs.

30. The apparatus according to claim 27, wherein:

at least two of said conductors of said multi-pole are connected together on the end opposite to said matching plug.

31. An apparatus according to claim 27, wherein:

all conductors of said multi-pole are open ended on the end opposite to the said matching plug.

32. An apparatus according to claim 27, wherein:

at least two conductors of said multi-pole are terminated to a capacitor on the end opposite to the said matching plug.

33. An apparatus according to claim 27, wherein:

at least two conductors of said multi-pole are terminated to an inductor on the end opposite to the said matching plug.

34. An apparatus according to claim 27, wherein:

each of said electrodynamic profiles forms a round body,

said body facing said multipole, and

electromagnetic property of said body alters in the azimuth direction.

35. An apparatus according to claim 34, wherein:

said body has the altering in the azimuth direction radius.

36. An apparatus according to claim 34, wherein:

said body has the altering in the azimuth direction width.

37. An apparatus according to claim 34, wherein:

each of said electrodynamic profiles is formed by a conducting material.

38. An apparatus according to claim 34, wherein:

each of said electrodynamic profiles is formed by a dielectric material.

39. An apparatus according to claim 34, wherein:

each of said electrodynamic profiles is formed by a magnetic material.

40. An apparatus according to claim 34, wherein:

each of said electrodynamic profiles is formed by a metal coating on the dielectric ring.

41. An apparatus according to claim 40, wherein:

said metal coating forms a ring with alternating width.

42. An apparatus according to claim 40, wherein:

said metal coating forms a periodic in the azimuth direction row of conducting members, not connected one to another.

43. An apparatus according to claim 40, wherein:

said metal coating has a configuration of a meander line.

44. An apparatus according to claim 40, wherein:

said metal coating has a configuration of a regular comb.

45. An apparatus according to claim 40, wherein:

said metal coating has the form of a comb with inclined fingers.

46. An apparatus of claim 22, wherein said measuring circuit includes at least one frequency generator.

47. An apparatus of claim 46, wherein said frequency generator is a radio frequency generator.

48. An apparatus of claim 22, wherein said measuring circuit includes a transducer and a converter.

49. An apparatus of claim 22, wherein said distribution by said sensitive slow-wave structure is in a given ratio.

50. An apparatus of claim 22, wherein:

said slow-wave structure forming a multi-pole.

51. An apparatus according to claim 50, wherein:

said multi-pole comprising at least two impedance conductors placed in parallel and configured as mirror images of one another turned through 180°

.

52. The apparatus according to claim 51, wherein:

said impedance conductors are made as radial spirals with opposite directions of winding.

53. The apparatus according to claim 51, wherein:

said impedance conductors are made as meander lines shifted one to another in the direction of the rotation on T/2, where T is the average period of a meander line.

54. An apparatus according to claim 50, wherein:

said multi-pole comprises two identical impedance conductors placed in the same surface.

55. An apparatus according to claim 54, wherein:

said impedance conductors form an interdigital comb.

56. An apparatus according to claim 50, wherein:

at least one surface of each of said electrodynamic profiles facing said multi-pole is placed perpendicularly to the rotation axis.

57. An apparatus according to claim 50, wherein:

at least one surface of each of said electrodynamic profiles facing said multi-pole is placed in parallel to the rotation axis.

58. An apparatus according to claim 22, wherein:

said impedance conductors are fashioned in the rotation plane.

59. An apparatus according to claim 22, wherein:

said impedance conductors are fashioned substantially in a manner of a cylindrical surface having an axis substantially coinciding with the rotation axis.

60. An apparatus according to claim 25, wherein:

said matching plug comprises at least one capacitor.

61. An apparatus according to claim 25, wherein:

said matching plug comprises at least one inductor.

62. An apparatus according to claim 25, wherein:

said matching plug includes a section of an additional two-conductor slow-wave structure.

63. An apparatus according to claim 62, wherein:

said additional slow-wave structure has the configuration of a coupled helix.

64. An apparatus according to claim 62, wherein:

said additional slow-wave structure has a wave impedance Z₂ which differs from the wave impedance Z₁ of said multi-pole by at least a factor of three.

65. An apparatus according to claim 25, wherein:

said resonator includes two said matching plugs connected to the measuring circuit in series.

66. An apparatus according to claim 25, wherein:

said resonator is connected to said measuring circuit through one of said matching plugs.

67. An apparatus according to claim 22, wherein:

at least one of said impedance conductors of said sensitive slow-wave structure has the configuration of a comb.

68. An apparatus according to claim 22, wherein:

at least one of said impedance conductors of said sensitive slow-wave structure has the configuration of a meander line.

69. An apparatus according to claim 22, wherein:

at least one of said impedance conductors of said sensitive slow-wave structure has the configuration of a radial spiral having a free outline with at least one axis of symmetry.