Articulation with controllable stiffness and force-measuring device

Patent metadata

Field	Value
Publication number	US-10016331-B2
Application number	US-201414896814-A
Country	US
Kind code	B2
Filing date	May 23, 2014
Priority date	Jun 13, 2013
Publication date	Jul 10, 2018
Grant date	Jul 10, 2018

Abstract

The subject matter of the invention is an articulation ( 1 ) with controllable stiffness and a force-measuring system, comprising a first device ( 20 ) that comprises a frame ( 4 ) having a curved face and connected to a first motor element ( 2 ), the first device ( 20 ) regulating the position of the articulation ( 1 ), and a second device ( 22 ) that regulates the stiffness of the articulation ( 1 ) and comprises a thrust element ( 15 ), the movement (D) of which determines the pre-compression of a resistive element ( 11 ) and thus the stiffness of the articulation ( 1 ); the first motor element ( 2 ) causes the frame ( 4 ) to rotate such that a wheel ( 8 ) of the second device ( 22 ) rolls on the curved face of the frame ( 4 ), causing the resistive element ( 11 ) to be compressed (C) via a transmission rod ( 7 ) associated with the wheel ( 8 ) and with the resistive element ( 11 ).

First claim

The invention claimed is:

1. An articulation ( 1 ) with controllable stiffness, comprising:
a first device ( 20 ) comprising a frame ( 4 ) connected to a first motor element ( 2 ), this first device ( 20 ) being configured to regulate a position of the articulation ( 1 ),
a second device ( 22 ) configured to regulate a stiffness of the articulation ( 1 ) and which anchors the first device ( 20 ) to the articulation ( 1 ), the second device ( 22 ) comprising:
a resistive element ( 11 ),
a transmission rod ( 7 ) having one end attached to the resistive element ( 11 ) and an opposite end comprising a wheel ( 8 ),
a thrust element ( 15 ) with a threaded spindle ( 16 ) through it, on which the resistive element ( 11 ) rests,
a second motor ( 12 ) attached to the spindle ( 16 ), which provides a displacement (D) to the thrust element ( 15 ) by a rotation of said spindle ( 16 ), and
a coupling body ( 13 ) on which the resistive element ( 11 ), the transmission rod ( 7 ), the thrust element ( 16 ), and the second motor ( 12 ) are arranged,

wherein the displacement D of the thrust element ( 15 ) determines a pre-compression of the resistive element ( 11 ), thus determining the articulation ( 1 ) stiffness, and the first motor element ( 2 ) provides a rotation to the frame ( 4 ) of the first device, wherein the frame ( 4 ) has a curved face, such that, with the rotation of the frame ( 4 ), the wheel ( 8 ) of the second device ( 22 ) rolls on the curved face of the frame ( 4 ), and the transmission rod ( 7 ) associated with said wheel ( 8 ) causes a compression (C) of the resistive element ( 11 ) of the second device ( 22 ), thus the compression (C) and the velocity at which it occurs determines a force F thrust developed by the resistive element ( 11 ).

2. The articulation ( 1 ) with controllable stiffness, according to claim 1 , wherein the resistive element ( 11 ) comprises an elastic element with a characteristic constant K, and/or a shock absorber element with a characteristic constant A, or a combination thereof.

3. The articulation ( 1 ) with controllable stiffness, according to claim 1 , wherein the second device ( 21 ) comprises a rotational measuring element ( 17 ) connected to the second motor ( 12 ), said rotational measuring element ( 17 ) counting the revolutions of a shaft of the second motor ( 12 ) such that the displacement (D) of the thrust element ( 15 ) can be determined by performing a conversion of the revolutions of the second motor ( 12 ) and of the pitch of the spindle ( 16 ), where a revolution of the second motor ( 12 ) is equivalent to the pitch of the spindle ( 16 ) in the linear displacement of the thrust element ( 15 ) associated with the spindle ( 16 ), so that the displacement (D) of the thrust element ( 15 ) can be determined by the relation D=Revolutions·Pitch.

4. The articulation ( 1 ) with controllable stiffness, according to claim 3 , wherein the second device ( 22 ) comprises a linear measurement element ( 9 ) and a graduated scale ( 10 ) attached to the transmission rod ( 7 ), such that compression experienced by the resistive element ( 11 ), and the velocity at which it occurs, associated to the rotation of the frame ( 4 ) can be determined through the linear measurement element ( 9 ), which measures the displacement of the transmission rod ( 7 ) on the graduated scale ( 7 ).

5. The articulation ( 1 ) with controllable stiffness, according claim 1 , wherein the resistive element ( 11 ) associated with its stiffness may be used to obtain the measure of a torque generated at the articulation ( 1 ) by the relation:
Torque= {right arrow over (b)}×{right arrow over (F)} n , which is converted into Torque= b ·F n ·sin(φ*)

where
b is a vector that represents a distance between an articulation rotation axis (O) and a point of contact of the frame ( 4 ) with the wheel ( 8 ), and
F n is the contact force between the surfaces of the frame ( 4 ) and of the wheel ( 8 ) in the radial direction of the wheel ( 8 );
φ* is an angle between the vector {right arrow over (b)} and the vector F n ,

where
b is obtained from the relation: {circumflex over (b)}=√{square root over ( OB 2 +R 2 −2· OB ·R·cos(β))} where β is the complementary angle which defines the inclination of the vector of the contact force {right arrow over (F)} n , and is obtained by the relation

β
=

OA
_

·

sin
⁢

⁢
θ

BA
_

,

 where θ is the deflection angle obtained from

θ
=

acos
[

OB
2

_

+

OA
_

2

-

BA
_

2

2
⁢

⁢

OB
_

·

OA
_

]

,

 where:
OB : distance from the rotation axis of the articulation ( 1 ) to the centre of curvature of the frame (B);

OA : distance from the articulation rotation axis (O) to the centre of the wheel (A);
BA : distance from the centre of the curvature of the frame (B) to the centre of the wheel (A),
φ* is obtained from the expression φ*=β+φ+θ,  where

φ
=

arc
⁢

⁢

cos
⁡

[

b
_

2

+

OA
_

2
-

Assignees

• Consejo Superior Investigacion
• Univ Madrid Politecnica

Inventors

• Cestari Soto Manuel Javier
• Sanz Merodio Daniel
• Garcia Armada Elena

Classifications

• A61F2/50

  Prostheses not implantable in the body {(closure means for urethra or rectum or for artificial body openings therefor A61F2/0004)} · CPC title

• A61F2002/503

  for adjusting elasticity, flexibility, spring rate or mechanical tension · CPC title

• A61H3/00 Primary

  Appliances for aiding patients or disabled persons to walk about (apparatus for helping babies to walk A47D13/04 {; applying electrical currents by contact electrodes for stimulating motor muscles, e.g. walking assistance A61N1/36003}) · CPC title

• B25J9/1694

  characterised by use of sensors other than normal servo-feedback from position, speed or acceleration sensors, perception control, multi-sensor controlled systems, sensor fusion · CPC title

• A61F2002/7635

  for measuring force, pressure or mechanical tension · CPC title