Method and apparatus for improved stiffness in the linkage assembly of a flexible arm

• US 20030165352A1
• Filed: 10/09/2002
• Published: 09/04/2003
• Est. Priority Date: 10/09/2001
• Status: Active Grant

• Current Assignee: Terumo Cardiovascular Systems Corporation (Terumo Corporation)
• Original Assignee: Endoscopic Technologies Incorporated (Atricure, Inc.)
• Inventors: Geyster, Steve, Ibrahim, Tamer, Haubert, Thomas D., Gleeson, James, Prescott, James A.
• Granted Patent: US 6,860,668 B2
• Time in Patent Office: Days
• US Class Current: 403/56
• CPC Class Codes: A61B 1/00149 using articulated arms
• CPC Class Codes: A61B 17/02 for holding wounds open; Tractors specula A61B1/32 ; drainage appliances for wounds A61M27/00
• CPC Class Codes: A61B 2090/571 for clamping a support arm to a bed or other supports
• CPC Class Codes: A61B 90/50 Supports for surgical instruments, e.g. articulated arms
• CPC Class Codes: F16L 11/18 Articulated hoses, e.g. composed of a series of rings
• CPC Class Codes: F16M 11/14 with ball-joint ball-jointed hinges F16C11/06 ; adjustable mountings employing universal joints for lighting devices F21V21/26 - F21V21/30
• CPC Class Codes: F16M 11/40 by means of coilable or bendable legs or spiral shaped legs
• CPC Class Codes: F16M 13/02 for supporting on, or attaching to, an object, e.g. tree, gate, window-frame, cycle
• CPC Class Codes: F16M 2200/022 by friction
• CPC Class Codes: Y10T 403/32032 Plural ball and socket
• CPC Class Codes: Y10T 403/32041 Universal
• CPC Class Codes: Y10T 403/32311 Ball and socket

Abstract

The invention includes linkage assemblies comprising coupled links with metallic contact surfaces with improved stiffness. The inventors found significant mechanical problems with all previous descriptions of metallic contact links sufficient to preclude their commercial use. These metallic contact links are a significant improvement over existing plastic ball and metal joint, or all plastic beads as found in the prior art. The invention includes methods providing these links and high friction couplings between them, as well as the linkage assemblies and flexible arms resulting from these processes.

Claims

1. A flexible arm linkage assembly provided with a tensioning cable, comprising:

a first link forming a first contact surface composed of a first contact material and approximating a partial convex surface supporting said tensioning cable passing through said first contact surface;

a second link forming a second contact surface composed of a second contact material and approximating a partial concave surface supporting said tensioning cable passing through said second contact surface; and

a high friction coupling between said first link and said second link is created by said first contact surface contacting said second contact surface when induced by said tensioning cable;

wherein said first contact material is distinct from said second contact material;

wherein each of said first contact material and said second contact material is primarily composed of a respective metallic compound;

wherein said first contact surface composed of said first contact material contacting said second contact surface composed of said second contact material has a friction coefficient greater than each member of the collection comprising;

a friction coefficient value of 0.3;

said first contact surface composed of said first contact material contacting said second contact surface composed of said first contact material; and

said first contact surface composed of said second contact material contacting said second contact surface composed of said second contact material.

2. The apparatus of claim 1,

wherein each of said respective metallic compounds is primarily composed of at least one alloy containing at least one member of the collection comprising:

iron, copper, and titanium.

3. The apparatus of claim 2,

wherein each of said respective metallic compounds is primarily composed of an alloy belonging to the collection comprising:

stainless steel, titanium, and nitinol.

4. The apparatus of claim 1,

wherein said first link is composed primarily of said first contact material.

5. The apparatus of claim 4,

wherein said second link is composed primarily of said second contact material.

6. The apparatus of claim 1,

wherein said first contact surface composed of said first contact material contacting said second contact surface composed of said second contact material has said friction coefficient greater than said friction coefficient value of 0.35.

7. The apparatus of claim 6,

wherein said first contact surface composed of said first contact material contacting said second contact surface composed of said second contact material has said friction coefficient greater than said friction coefficient value of 0.375.

8. The apparatus of claim 7,

wherein said first contact surface composed of said first contact material contacting said second contact surface composed of said second contact material has said friction coefficient greater than said friction coefficient value of 0.3875.

9. The apparatus of claim 1,

wherein said second link is composed primarily of said second contact material.

10. The apparatus of claim 1,

wherein said first contact surface contacting said second contact surface when induced by said tensioning cable further provides a maximal static friction combined with a maximal kinetic friction between said first link and said second link.

11. The apparatus of claim 1,

wherein said first link further forms a third contact surface composed of a third contact material and approximating a second partial concave surface supporting said tensioning cable passing through said third contact surface;

wherein said apparatus is further comprised of

a third link forming a fourth contact surface composed of a fourth contact material and approximating a second partial convex surface supporting said tensioning cable passing through said fourth contact surface; and

a second high friction coupling between said first link and said third link is created by said third contact surface contacting said fourth contact surface when induced by said tensioning cable;

wherein each of said third and said fourth contact material is primarily composed of a respective metallic compound.

12. The apparatus of claim 11,

wherein said third contact material is distinct from said fourth contact material;

wherein said third contact surface composed of said third contact material contacting said fourth contact surface composed of said fourth contact material has a higher friction coefficient than each member of the collection comprising;

said third contact surface composed of said third contact material contacting said fourth contact surface composed of said third contact material; and

said third contact surface composed of said fourth contact material contacting said fourth contact surface composed of said fourth contact material.

13. The apparatus of claim 11,

wherein said third contact material is essentially said second contact material.

14. The apparatus of claim 13,

wherein said fourth contact material is essentially said first contact material.

15. The apparatus of claim 11,

wherein said partial concave surface is distinct from said second partial concave surface.

16. The apparatus of claim 11,

wherein said first contact surface essentially borders said third contact surface.

17. The apparatus of claim 11,

wherein said first link includes said first contact surface coupled to said third contact surface by a hollow rod supporting said tensioning cable traversing through said first contact surface and through said third contact surface.

18. A method making a flexible arm linkage assembly with a tensioning cable, comprising the steps of:

providing a first link forming a first contact surface composed of a first contact material and approximating a partial convex surface supporting said tensioning cable passing through said first contact surface;

providing a second link forming a second contact surface composed of a second contact material and approximating a partial concave surface supporting said tensioning cable passing through said second contact surface; and

said tensioning cable inducing a contact between said first contact surface and said second contact surface to create a high friction coupling between said first link and said second link;

wherein said first contact material is distinct from said second contact material;

wherein each of said first contact material and said second contact material is primarily composed of a respective metallic compound;

wherein said first contact surface composed of said first contact material contacting said second contact surface composed of said second contact material has a friction coefficient greater than each member of the collection comprising;

a friction coefficient value of 0.3;

said first contact surface composed of said first contact material contacting said second contact surface composed of said first contact material; and

said first contact surface composed of said second contact material contacting said second contact surface composed of said second contact material.

19. The method of claim 18,

wherein each of said respective metallic compounds is primarily composed of at least one alloy containing at least one member of the collection comprising:

iron, copper, and titanium.

20. The method of claim 19,

wherein each of said respective metallic compounds is primarily composed of an alloy belonging to the collection comprising:

stainless steel, titanium, and nitinol.

21. The method of claim 18,

wherein said first link is composed primarily of said first contact material.

22. The method of claim 21,

wherein said second link is composed primarily of said second contact material.

23. The method of claim 18,

wherein said first contact surface composed of said first contact material contacting said second contact surface composed of said second contact material has said friction coefficient greater than said friction coefficient value of 0.35.

24. The method of claim 23,

wherein said first contact surface composed of said first contact material contacting said second contact surface composed of said second contact material has said friction coefficient greater than said friction coefficient value of 0.375.

25. The method of claim 24,

wherein said first contact surface composed of said first contact material contacting said second contact surface composed of said second contact material has said friction coefficient greater than said friction coefficient value of 0.3875.

26. The method of claim 18,

wherein said second link is composed primarily of said second contact material.

27. The method of claim 18,

wherein the step said tensioning cable inducing contact between said first contact surface and said second contact surface is further comprised of the steps of

said tensioning cable inducing contact between said first contact surface and said second contact surface providing a maximal static friction combined with a maximal kinetic friction between said first link and said second link.

28. The method of claim 18,

wherein said first link further forms a third contact surface composed of a third contact material;

wherein said method is further comprised of the steps of;

providing a third link forming a fourth contact surface composed of a fourth contact material and approximating a second partial convex surface supporting said tensioning cable passing through said fourth contact surface; and

said tensioning cable inducing a second high friction coupling between said first link and said third link by said third contact surface contacting said fourth contact surface when induced by said tensioning cable;

wherein each of said third contact material and said fourth contact material is primarily composed of a respective metallic compound.

29. The method of claim 28,

wherein said third contact material is distinct from said fourth contact material;

wherein said third contact surface composed of said third contact material contacting said fourth contact surface composed of said fourth contact material has a higher friction coefficient than each member of the collection comprising;

said third contact surface composed of said third contact material contacting said fourth contact surface composed of said third contact material; and

said third contact surface composed of said fourth contact material contacting said fourth contact surface composed of said fourth contact material.

30. The method of claim 28,

wherein said third contact material is essentially said second contact material.

31. The method of claim 30,

wherein said fourth contact material is essentially said first contact material.

32. The method of claim 28,

wherein said partial concave surface is distinct from said second partial concave surface.

33. The method of claim 28,

wherein said partial convex surface is distinct from said second partial convex surface.

34. The method of claim 18,

wherein said partial convex surface further approximates a hemisphere supporting said tensioning cable passing through said first contact surface.

35. The method of claim 18,

wherein said partial concave surface further approximates a partial cone supporting said tensioning cable passing through said second contact surface.

36. Said flexible arm linkage assembly as a product of the process of claim 18.

37. A method of making a flexible arm, comprising the steps of claim 18 providing a flexible arm linkage assembly.

38. Said flexible arm as a product of the process of claim 37.

39. A flexible arm linkage assembly provided with a tensioning cable, comprising:

a first link forming a first contact surface composed of a first contact material and approximating a partial convex surface supporting said tensioning cable passing through said first contact surface;

a second link forming a second contact surface composed of a second contact material and approximating a partial concave surface supporting said tensioning cable passing through said second contact surface; and

a high friction coupling between said first link and said second link is created by said first contact surface contacting said second contact surface when induced by said tensioning cable;

wherein each of said first contact material and said second contact material is primarily composed of a respective metallic compound;

wherein said first contact surface contacting said second contact surface when induced by said tensioning cable further provides a maximal static friction combined with a maximal kinetic friction between said first link and said second link through a contact region;

wherein said contact region is smaller than a maximal contact region obtained from altering at least one member of the collection comprising said first contact surface and said second contact surface; and

wherein said first contact surface composed of said first contact material contacting said second contact surface composed of said second contact material has a friction coefficient greater than a friction coefficient value of 0.3.

40. The apparatus of claim 39,

wherein each of said respective metallic compounds is primarily composed of at least one alloy containing at least one member of the collection comprising:

iron, copper, and titanium.

41. The apparatus of claim 40,

wherein each of said respective metallic compounds is primarily composed of an alloy belonging to the collection comprising:

stainless steel, titanium, and nitinol.

42. The apparatus of claim 39,

wherein said first link is composed primarily of said first contact material.

43. The apparatus of claim 42,

wherein said second link is composed primarily of said second contact material.

44. The apparatus of claim 39,

wherein said first contact surface composed of said first contact material contacting said second contact surface composed of said second contact material has said friction coefficient greater than said friction coefficient value of 0.35.

45. The apparatus of claim 44,

wherein said first contact surface composed of said first contact material contacting said second contact surface composed of said second contact material has said friction coefficient greater than said friction coefficient value of 0.375.

46. The apparatus of claim 45,

wherein said first contact surface composed of said first contact material contacting said second contact surface composed of said second contact material has said friction coefficient greater than said friction coefficient value of 0.3875.

47. The apparatus of claim 39,

wherein said second link is composed primarily of said second contact material.

48. The apparatus of claim 39,

wherein said first link further forms a third contact surface composed of a third contact material and approximating a second partial concave surface supporting said tensioning cable passing through said third contact surface;

wherein said apparatus is further comprised of

a third link forming a fourth contact surface composed of a fourth contact material and approximating a second partial convex surface supporting said tensioning cable passing through said fourth contact surface; and

a second high friction coupling between said first link and said third link is created by said third contact surface contacting said fourth contact surface when induced by said tensioning cable;

wherein each of said third and said fourth contact material is primarily composed of a respective metallic compound.

49. The apparatus of claim 48,

wherein said third contact surface contacting said fourth contact surface when induced by said tensioning cable further provides a second maximal static friction combined with a second maximal kinetic friction between said first link and said third link through a second contact region;

and

wherein said second contact region is smaller than a second maximal contact region obtained from altering at least one member of the collection comprising said third contact surface and said fourth contact surface.

50. The apparatus of claim 49,

wherein said third contact material is essentially said second contact material.

51. The apparatus of claim 50,

wherein said fourth contact material is essentially said first contact material.

52. The apparatus of claim 49,

wherein said third contact surface approximates a second partial concave surface supporting said tensioning cable passing through said third contact surface.

53. The apparatus of claim 52,

wherein said partial concave surface is distinct from said second partial concave surface.

54. The apparatus of claim 52,

wherein said first contact surface essentially borders said third contact surface.

55. The apparatus of claim 52,

wherein said first link includes said first contact surface coupled to said third contact surface by a hollow rod supporting said tensioning cable traversing through said first contact surface and through said third contact surface.

56. The apparatus of claim 49,

wherein said partial convex surface is distinct from said second partial convex surface.

57. The apparatus of claim 39,

wherein said first contact material is distinct from said second contact material.

58. The apparatus of claim 57,

wherein said first contact surface composed of said first contact material contacting said second contact surface composed of said second contact material has a higher friction coefficient than each member of the collection comprising:

said first contact surface composed of said first contact material contacting said second contact surface composed of said first contact material; and

said first contact surface composed of said second contact material contacting said second contact surface composed of said second contact material.

59. The apparatus of claim 39,

wherein said partial convex surface further approximates a hemisphere supporting said tensioning cable passing through said first contact surface.

60. The apparatus of claim 39,

wherein said partial concave surface further approximates a partial cone supporting said tensioning cable passing through said second contact surface.

61. A method of making flexible arm linkage assembly provided with a tensioning cable, comprising the steps of:

providing a first link forming a first contact surface composed of a first contact material and approximating a partial convex surface supporting said tensioning cable passing through said first contact surface;

providing a second link forming a second contact surface composed of a second contact material and approximating a partial concave surface supporting said tensioning cable passing through said second contact surface; and

said tensioning cable inducing a high friction coupling between said first link and said second link by said first contact surface contacting said second contact surface;

wherein the step said tensioning cable inducing said high friction coupling is further comprised of the step;

said first contact surface contacting said second contact surface when induced by said tensioning cable providing a maximal static friction combined with a maximal kinetic friction between said first link and said second link through a contact region;

wherein each of said first contact material and said second contact material is primarily composed of a respective metallic compound;

wherein said contact region is smaller than a maximal contact region obtained from altering at least one member of the collection comprising said first contact surface and said second contact surface; and

wherein said first contact surface composed of said first contact material contacting said second contact surface composed of said second contact material has a friction coefficient greater than a friction coefficient value of 0.3.

62. The method of claim 61,

wherein each of said respective metallic compounds is primarily composed of at least one alloy containing at least one member of the collection comprising:

iron, copper, and titanium.

63. The method of claim 62,

wherein each of said respective metallic compounds is primarily composed of an alloy belonging to the collection comprising:

stainless steel, titanium, and nitinol.

64. The method of claim 61,

wherein said first link is composed primarily of said first contact material.

65. The method of claim 64,

wherein said second link is composed primarily of said second contact material.

66. The method of claim 61,

wherein said first contact surface composed of said first contact material contacting said second contact surface composed of said second contact material has said friction coefficient greater than said friction coefficient value of 0.35.

67. The method of claim 66,

wherein said first contact surface composed of said first contact material contacting said second contact surface composed of said second contact material has said friction coefficient greater than said friction coefficient value of 0.375.

68. The method of claim 67,

wherein said first contact surface composed of said first contact material contacting said second contact surface composed of said second contact material has said friction coefficient greater than said friction coefficient value of 0.3875.

69. The method of claim 61,

wherein said second link is composed primarily of said second contact material.

70. The method of claim 61,

wherein said first link further forms a third contact surface composed of a third contact material and approximating a second partial concave surface supporting said tensioning cable passing through said third contact surface;

wherein said method is further comprised of the steps of;

providing a third link forming a fourth contact surface composed of a fourth contact material and approximating a second partial convex surface supporting said tensioning cable passing through said fourth contact surface; and

said tensioning cable inducing a second high friction coupling between said first link and said third link by said third contact surface contacting said fourth contact surface;

wherein each of said third and said fourth contact material is primarily composed of a respective metallic compound.

71. The method of claim 70,

wherein the step said tensioning cable inducing said second high friction coupling is further comprised of the step:

said third contact surface contacting said fourth contact surface when induced by said tensioning cable providing a second maximal static friction combined with a second maximal kinetic friction between said first link and said third link through a second contact region; and

wherein said second contact region is smaller than a second maximal contact region obtained from altering at least one member of the collection comprising said third contact surface and said fourth contact surface.

72. The method of claim 71,

wherein said third contact material is essentially said second contact material.

73. The method of claim 72,

wherein said fourth contact material is essentially said first contact material.

74. The method of claim 71,

wherein said third contact surface approximates a second partial concave surface supporting said tensioning cable passing through said third contact surface.

75. The method of claim 74,

wherein said partial concave surface is distinct from said second partial concave surface.

76. The method of claim 74,

wherein said first contact surface essentially borders said third contact surface.

77. The method of claim 74,

wherein said first link includes said first contact surface coupled to said third contact surface by a hollow rod supporting said tensioning cable traversing through said first contact surface and through said third contact surface.

78. The method of claim 71,

wherein said partial convex surface is distinct from said second partial convex surface.

79. The method of claim 61,

wherein said first contact material is distinct from said second contact material.

80. The method of claim 79,

wherein said first contact surface composed of said first contact material contacting said second contact surface composed of said second contact material has a higher friction coefficient than each member of the collection comprising:

said first contact surface composed of said first contact material contacting said second contact surface composed of said first contact material; and

said first contact surface composed of said second contact material contacting said second contact surface composed of said second contact material.

81. The method of claim 61,

wherein said partial convex surface further approximates a hemisphere supporting said tensioning cable passing through said first contact surface.

82. The method of claim 61,

wherein said partial concave surface further approximates a partial cone supporting said tensioning cable passing through said second contact surface.

83. Said flexible arm linkage assembly as a product of the process of claim 61.

84. A method of making a flexible arm, comprising the steps of claim 61 providing a flexible arm linkage assembly.

85. Said flexible arm as a product of the process of claim 84.