Jamming methods and apparatus
A reconfigurable device comprises flexible bladder that encloses a jammable material. The geometry of the device can be altered by unjamming the jammable material (making it flexible), changing the shape of the device while it is flexible, and then jamming the jammable material (making it rigid). In some applications of this invention, a joint connects rigid arms. The ends of the rigid arms are enclosed in the bladder. By varying the stiffness of the jammable material in the bladder, the stiffness of the joint can be controlled.
1. A joint that comprises, in combination:
(a) a first rigid structural member and a second rigid structural member;
(b) a jammable material, the rigidity of which jammable material depends on the density of the jammable material, such that the jammable material becomes more rigid as the density of the jammable material increases in response to an increase in pressure;
(c) a flexible container; and
(d) means for changing the density of the jammable material sufficiently to vary the rigidity of the jammable material;
wherein
(i) the jammable material is positioned inside the flexible container,
(ii) an end of the first rigid structural member is inside the flexible container and is in direct physical contact with the jammable material, and
(iii) an end of the second rigid structural member is inside the flexible container and is in direct physical contact with the jammable material.
2. The joint of claim 1 , wherein the end of the first structural member and the end of the second structural member are annular and interlock directly with each other.
3. The joint of claim 1 , wherein the end of the first structural member and the end of the second structural member are annular and the joint further comprises an additional annular part that interlocks directly with each of the ends, respectively.
4. The joint of claim 1 , wherein the joint further comprises a mechanical connection between the end of the first structural member and the end of the second structural member, which connection permits the structural members to be displaced relative to each other in only one direction.
5. The joint of claim 1 , wherein the jammable material comprises a granular solid in a liquid.
6. The joint of claim 1 , wherein the flexible container comprises an elastomer.
7. The joint of claim 1 , wherein the jammable material comprises a fluid, a granular solid, and other solid components in addition to the granular solid, which other solid components have a different material composition than the granular solid.