Variable Stiffness Orthoses Using Granular Jamming
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Solution Overview
Problem
Current orthotic insoles face challenges such as limited customizability, material densification issues, and the need for multiple devices for different activities, as they are made from foams that cannot adjust mechanical properties post-manufacturing and are prone to densification failure under weight application.
Innovation Solution
The use of variable stiffness orthoses that employ granular jamming principles, where air impermeable bladders contain granular particulates whose stiffness is adjusted by controlling internal pressure through valves and a pressure controller, allowing for customizable and adaptable mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If foam and plastic materials are used in orthotic insoles, then the device provides structural support and shock absorption, but the mechanical properties cannot be adjusted after manufacturing and the materials are prone to densification failure
Solution Approach 1:
The patent applies parameter changes by using granular particulates (such as sand, rice, or plastic beads) instead of traditional foam materials. The key parameter that changes is the density of the granular material, which can be adjusted by compacting the grains more tightly or leaving them looser. This allows the mechanical properties of the orthotic device to be modified after manufacturing by changing the packing density of the granules, thereby providing both reliability (no densification failure) and adaptability (adjustable stiffness).
Solution Approach 2:
The patent employs composite materials by combining granular particulates with a flexible membrane or container structure. The granular material (sand, rice, plastic beads) is enclosed within a flexible membrane that allows the granules to shift and compact. This composite structure provides both the structural support needed for orthotic function and the ability to adjust mechanical properties by changing the granule packing, resolving the contradiction between reliability and adaptability.
2Adaptability or versatility
If multiple types of foams are used at different areas of the insole, then the device provides customized support and energy absorption, but the manufacturing cost and complexity increase significantly
Solution Approach 1:
The patent applies local quality by using a single type of granular material (such as sand or plastic beads) distributed throughout the insole, but creating different mechanical properties at different locations through variations in granule packing density. The flexible membrane allows selective compaction of granules in specific areas corresponding to different foot regions (heel, arch, forefoot), providing customized support without requiring multiple foam types or complex multi-material manufacturing processes.
3Adaptability or versatility
If a single orthotic device is designed to serve multiple activities, then the need for multiple devices is reduced, but the device must accommodate conflicting mechanical property requirements
Solution Approach 1:
The patent applies dynamics by making the mechanical properties of the orthotic device changeable and adjustable rather than fixed. The granular material within the flexible membrane can be dynamically reconfigured by the user - compacted for high-support activities like running, loosened for low-support activities like casual walking. This dynamic adaptability allows a single device to reliably perform across multiple activities by optimizing the granule packing density to match the specific mechanical requirements of each activity.
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
This approach enables a single orthotic device to suit various applications and activities by adjusting stiffness and energy absorption, avoiding densification failures and reducing the need for multiple devices, thus enhancing user comfort and reducing manufacturing costs.
Implementation Method 1
variable stiffness devices that use the principles of granular jamming
Implementation Method 2
The cell can be configured to maintain a negative internal pressure relative to an area external to the outer bladder
Data Source
AI summary
Embodiments of the present disclosure relate generally to variable stiffness devices, including orthoses, that use the principles of granular jamming. In some embodiments, a device may comprise a cell having an air impermeable outer bladder. The outer bladder of the cell can define an internal pocket. A plurality of granular particulates may be disposed within the first cell. The stiffness of the cell can be altered by altering the negative internal pressure of the cell, thereby causing the granular particulates to compact, or jam. In some embodiments, a plurality of cells may be disposed within a device. The location of each of the plurality of cells may correspond to a location of a user's foot. The mechanical characteristics of each cell of the plurality of cells may be independently adjusted by adjusting the negative internal pressure of the cell.