Variable stiffness devices and methods of use

Patent metadata

Field	Value
Publication number	US-10028855-B2
Application number	US-201615154443-A
Country	US
Kind code	B2
Filing date	May 13, 2016
Priority date	May 14, 2015
Publication date	Jul 24, 2018
Grant date	Jul 24, 2018

Abstract

Variable stiffness devices and methods of their use are provided. In some embodiments, a variable stiffness device comprises an inner member defining a compartment for receiving an actuating fluid; an outer member disposed around the inner member; and a granular medium disposed between the inner member and the outer member; wherein the inner member is being moveable in a radial direction from a relaxed state to an expanded state by introducing the actuating fluid into the compartment of the inner member to compress the granular medium against the outer member to increase the stiffness of the device.

First claim

What is claimed is:

1. A variable stiffness device comprising:
an inner member defining a compartment for receiving an actuating fluid;
an outer member disposed around the inner member; and
a granular medium disposed between the inner member and the outer member;
wherein the inner member is being moveable in a radial direction from a relaxed state to an expanded state by introducing the actuating fluid into the compartment of the inner member to compress the granular medium against the outer member to increase the stiffness of the device and wherein the outer member has a fixed size in the radial direction and a variable size in a longitudinal direction.

2. The variable stiffness device of claim 1 wherein the inner member is made from an elastic material and the outer member is made from a non-stretchable material.

3. The variable stiffness device of claim 1 wherein the outer member is reinforced on a side to direct bending of the outer member under a load.

4. The variable stiffness device of claim 1 wherein the outer member is pre-bent to a side to direct bending of the outer member under a load.

5. The variable stiffness device of claim 1 wherein the granular medium is compressible.

6. The variable stiffness device of claim 1 wherein the granular medium is a mixture of rubber pellet granules ranging from about 1 to about 3 mm in diameter.

7. The variable stiffness device of claim 1 wherein the granular medium has a packing factor between about 0.55 and about 0.74 at atmospheric pressure.

8. The variable stiffness device of claim 1 wherein the variable stiffness device is incorporated into an article of clothing.

9. A variable stiffness device comprising:
a first inner members, the first inner member defining a first compartment for receiving a first actuating fluid;
a second inner member wrapped around the first inner member, the second inner member defining a second compartment for receiving a second actuating fluid;
an outer member disposed around the inner member; and
a granular medium disposed between the second inner member and the outer member;
wherein the first inner member is configured to expand in a longitudinal direction by introducing the first actuating fluid into the first compartment of the first inner member to expand the variable stiffness device in the longitudinal direction; and
wherein the second inner member is configured to expand in a radial direction by introducing the second actuating fluid into the second compartment of the second inner member to compress the granular medium against the outer member to increase the stiffness of the variable stiffness device.

10. The variable stiffness device of claim 9 wherein the outer member has a fixed size in the radial direction and a variable size in a longitudinal direction.

11. The variable stiffness device of claim 9 wherein the outer member is reinforced on a side to direct bending of the outer member under a load.

Assignees

• Worcester Polytech Inst

Inventors

• Popovic Marko
• Sridar Saivimal
• Majeika Corey
• Deisadze Nicholas
• Giancarlo Erika

Classifications

• A61F5/058 Primary

  Splints · CPC title

• A61F2002/5066

  Muscles · CPC title

• A61F5/01

  Orthopaedic devices, e.g. long-term immobilising or pressure directing devices for treating broken or deformed bones such as splints, casts or braces · CPC title

• A61F2002/503

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

• B25J19/068

  Actuating means with variable stiffness · CPC title