Variable-Stiffness Orthotic Shell Using Vacuum Layer Jamming
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Solution Overview
Problem
Existing wearable robot interfaces struggle to adequately anchor to complex anatomical geometries, particularly in cases of deformities, while maintaining rigidity and adaptability to support constraint reactions and lock joints in predetermined positions.
Innovation Solution
An orthotic shell with a laminar structure comprising flexible laminar elements and a vacuum-sealed hermetic wrapper that transitions between deformable and rigid configurations, utilizing 'layer jamming' and 'granular jamming' to conform to complex anatomical shapes and lock joints in place.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rigid braces are used to anchor the robot and support constraint reactions, then the anchoring strength and joint locking capability are improved, but the adaptability to complex anatomical geometries and deformities deteriorates
Solution Approach 1:
The orthotic shell employs variable stiffness characteristics, transitioning from a flexible state during donning to a rigid state during operation. This is achieved through a granular jamming mechanism where granules inside the shell can be redistributed to increase internal friction and stiffness, allowing the same structure to adapt to different anatomical geometries while maintaining anchoring strength
Solution Approach 2:
The shell's mechanical properties are dynamically changed by altering the packing density and distribution of internal granules. By changing the physical state of the granular material (from loose to compacted), the shell transitions between compliant and rigid states, resolving the contradiction between adaptability and strength
2Adaptability or versatility
If adjustable bands or straps are used to adapt the shape and size of rigid braces, then the adaptability to anthropometry is improved, but the device complexity and difficulty of proper fitting deteriorates
Solution Approach 1:
The orthotic shell is designed to self-adapt to the user's anatomy through the granular jamming mechanism. The shell automatically adjusts its shape and stiffness to conform to the anatomical segment without requiring complex adjustment procedures, straps, or bands, thereby reducing fitting complexity while maintaining high adaptability
3Adaptability or versatility
If the orthotic shell transitions between deformable and rigid states, then the adaptability during donning and anchoring strength during operation are improved, but the device complexity deteriorates
Solution Approach 1:
The orthotic shell utilizes a flexible shell structure containing granular material. This simple yet effective design allows the shell to be deformable during donning and then rigid during operation, achieving variable stiffness without complex mechanisms. The flexibility of the shell combined with the granular jamming principle provides a straightforward solution to the contradiction between adaptability and structural complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The orthotic shell effectively anchors to complex anatomical segments, providing rigidity and adaptability to support constraint reactions and lock joints, even in deformities, by transitioning between deformable and rigid states to fit specific anthropometry.
Implementation Method 1
The orthotic shell with a laminar structure comprising at least three overlapped layers consisting of respective laminar elements of flexible material and a hermetic wrapper surrounding the laminar structure and at least one granular chamber disposed inside the hermetic wrapper
Implementation Method 2
a vacuum-sealed hermetic wrapper that transitions between deformable and rigid configurations
Implementation Method 3
utilizing 'layer jamming' and 'granular jamming' to conform to complex anatomical shapes
Implementation Method 4
laminar structure comprising at least three overlapped layers consisting of respective laminar elements of flexible material
Implementation Method 5
support constraint reactions and lock joints in predetermined positions
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3~3A
AI summary
An orthotic shell (10) comprising at least one laminar structure (100), comprising at least two overlapped layers, each layer comprising a plurality of laminar elements (110,120,130), said laminar elements (110,120,130) being made of flexible material and arranged to pass between a planar geometry, where the laminar structure (100) has a two-dimensional shape and is substantially parallel to a reference plane n, and a deformed geometry, where the laminar structure (100) has a three-dimensional shape. The orthotic shell (10) also comprises a hermetic wrapper (300) arranged to contain said at least two layers, said hermetic wrapper (300) arranged to be put under vacuum. In particular, each laminar element (110,120,130) comprises a central portion (111,121,131) and n > 3 connecting portions (115,125,135), each connection portion (115,125,135) having an elongated shape that extends from the central portion (111,121,131) along a longitudinal direction x. In particular, laminar elements (110,120,130) of a same layer are separated from each other. Advantageously, each connection portion (115) of each laminar element (110) of a first layer is arranged to overlap, at least partially, a connection portion (125) of a laminar element (120) of a second layer adjacent to the first layer in order to allow a connection of laminar elements (110,120,130) of adjacent layers. In particular, the orthotic shell (10) is arranged to pass between a deformable configuration, wherein the connecting portions (115,125,135) are arranged to bend for making the laminar elements (110,120,130) pass between the planar geometry and the deformed geometry, and a rigid configuration, wherein the hermetic wrapper (200) is vacuum- packed and the connecting portions (115,125,135) are subjected to mutual friction, rigidly locking each other in their position.