Membrane integrated lamina emergent torsion joint
A lamina emergent torsional (LET) joint that includes an integrated membrane to reduce, or eliminate, certain unwanted motions and/or displacements associated with the operation of the LET joint is disclosed. The membrane-integrated LET joint (i.e., M-LET) can be used as a hinge for a lamina emergent mechanism and/or as a surrogate fold for an origami application to ensure accurate and repeatable transitions from a planar (i.e., lamina) state to a non-planar (i.e., lamina-emergent) state, and vice versa.
1. A membrane-integrated lamina emergent torsional joint comprising:
torsional segments that are substantially parallel to one another, each torsional segment capable of a twisting motion along a length between end portions of the torsional segment;
a first member and a second member that are coupled by the torsional segments, and that can be configured into a folded configuration or an unfolded configuration by a hinge movement facilitated by the twisting motion of one or more of the torsional segments; and
a membrane coupled to at least the first member and the second member, the membrane configured to allow the hinge movement while reducing, or preventing, other movements, wherein the membrane is adhered to the first member and the second member and not adhered to the torsional segments.
2. The membrane-integrated lamina emergent torsional joint according to claim 1 , wherein the torsional segments, the first member, the second member are formed from a planar sheet of material.
3. The membrane-integrated lamina emergent torsional joint according to claim 1 , wherein in the folded configuration the first member and the second member define an angle with a vertex of the angle corresponding to the torsional segments.
4. The membrane-integrated lamina emergent torsional joint according to claim 3 , wherein the angle of the folded configuration is greater than zero degrees and less than 180 degrees.
5. The membrane-integrated lamina emergent torsional joint according to claim 1 , wherein in the unfolded configuration the first member, the second member, and the torsional segments substantially define a plane.
6. The membrane-integrated lamina emergent torsional joint according to claim 1 , wherein the membrane is adhered to the first member, the second member, and the torsional segments.
7. The membrane-integrated lamina emergent torsional joint according to claim 1 , wherein the first member, the second member, and the torsional segments form an outside LET joint configuration.
8. The membrane-integrated lamina emergent torsional joint according to claim 7 , wherein the outside LET joint configuration includes:
the torsional segments connected to each other at each end by frame segments;
one of the torsional segments is connected at a midpoint along its length to the first member by a first coupling block; and
another of the torsional segments connected at a midpoint along its length to the second member by a second coupling block.
9. The membrane-integrated lamina emergent torsional joint according to claim 1 , wherein:
the torsional segments, the first member, the second member are defined by a first planar sheet of material, and wherein the lamina emergent torsional joint further includes:
a second planar sheet of material that defines torsional segments, a first member, and a second member that correspond to those of the first sheet, the second sheet and the first sheet bonded to and separated by the membrane.
10. The membrane-integrated lamina emergent torsional joint according to claim 1 , wherein the hinge movement is unidirectional.
11. The membrane-integrated lamina emergent torsional joint according to claim 1 , wherein the other movements include a tensile deflection of the torsional segments or a rotational deflection of the torsional segments.
12. A method for reducing parasitic motion in a lamina emergent mechanism comprising:
coupling a membrane to a planar layer, the planar layer defining a plurality of torsional segments between a first member and a second member, the coupling including bonding the membrane to the first member and the second member and not bonding the membrane to the plurality of torsional segments; and
folding the first member and the second member, wherein the folding includes:
applying a force to the first member or the second member, the applied force resulting in a twisting motion of at least one of the plurality of torsional segments and a parasitic motion of at least one of the plurality of torsional segments;
allowing, using the membrane, the twisting motion; and
resisting, using the membrane, the parasitic motion.
13. The method according to claim 12 , further comprising:
coupling the membrane to a surface of a second planar layer, the second planar layer an approximate duplicate of the planar layer, and the membrane between the planar layer and the second planar layer.
14. The method according to claim 12 , wherein the coupling the membrane to the planar layer includes:
bonding the membrane to the first member, the second member, and the plurality of torsional segments.
15. A surrogate fold for an origami mechanism comprising:
a first member and a second member configurable into a folded configuration or an unfolded configuration based on movement provided by a lamina emergent torsional joint coupled between the first member and the second member; and
a membrane coupled to a planar surface defined by the first member and the second member in the unfolded configuration, the membrane allowing a first hinge movement of the lamina emergent torsional joint in a first direction and resisting a second hinge movement of the lamina emergent torsional joint in a second direction that is opposite to the first, wherein the membrane is adhered to the first member and the second member and not adhered to torsional segments coupled between the first member and the second member.