MR Fluid Orthotic Joint for Ankle Rotation Control
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Solution Overview
Problem
Conventional lower-limb joint orthoses for paralyzed individuals, particularly those with foot paralysis, are cumbersome and limit ankle movement, making independent walking difficult due to their complex structure and limited rotational range.
Innovation Solution
A lower-limb joint orthosis with an MR fluid-based orthotic joint that includes a stator with fan-shaped fluid chambers and a rotor with partition plates, connected by communication paths, where an electromagnet adjusts the viscosity of the MR fluid to control rotational resistance, allowing for sensitive operation and compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a hinge mechanism with locking and unlocking is incorporated to enable ankle movement, then the orthosis can provide rotational movement function, but the operation becomes complicated and cumbersome requiring operation of a locking member
Solution Approach 1:
The patent replaces the mechanical hinge mechanism with a rotary cylinder containing MR fluid. The viscosity of the MR fluid is controlled by magnetic force to provide the desired rotational resistance without mechanical locking members. This substitutes a complex mechanical system with a simpler field-based control system.
Solution Approach 2:
The patent changes the viscosity parameter of the MR fluid by adjusting the magnetic force applied to it. This allows continuous adjustment of rotational resistance from locked to free state without mechanical intervention, simplifying operation while maintaining adaptability.
2Adaptability or versatility
If a rotary cylinder with MR fluid is used to control ankle movement, then the orthosis can switch between locked and free states, but the structure becomes complicated and the size increases
Solution Approach 1:
The patent merges the fluid chambers into a single integrated rotary cylinder structure rather than using separate chambers. The partition plates within the cylinder create the necessary compartmentalization for MR fluid control, simplifying the overall structure while maintaining the locked/free state switching capability.
Solution Approach 2:
The rotary cylinder is divided into multiple fluid chambers separated by partition plates, with each chamber containing MR fluid. This segmentation allows independent control of different regions while using a compact cylindrical form factor, reducing overall device size compared to alternative configurations.
3Adaptability or versatility
If a rotary cylinder with MR fluid is used to control ankle movement, then the orthosis can switch between locked and free states, but the size of the orthosis increases
Solution Approach 1:
The partition plates and MR fluid chambers are nested within the rotary cylinder in a compact concentric arrangement. The shaft section rotates within the stator, with partition plates extending radially to create chambers. This nested configuration maximizes the use of internal space, achieving the required functionality in a minimal volume.
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 solution simplifies the structure, increases the range of ankle movement, and reduces the size of the orthosis, enabling more natural ankle motion and improved walking ability by automatically controlling rotational resistance based on weight shifts during walking.
Implementation Method 1
an MR fluid whose viscosity changes depending on a magnetic force is enclosed
Data Source
AI summary
A lower-limb joint orthosis includes a lower component supporting the foot region, an upper component attached to the lower-limb, and an orthotic joint coupling both components. The orthotic joint includes: a stator including some fluid chambers in which an MR fluid is enclosed; and a rotor including partition plates protruding into the respective fluid chambers. The stator includes a communication path between the anterior chamber and the posterior chamber. The rotor includes connection paths that connect the anterior chambers together, and connect the posterior chambers together. An electromagnet is placed on a side surface of the communication path so that a rotational resistance of the lower component and the upper component is adjusted by adjusting a magnetic force to control the viscosity of the MR fluid that flows through the communication path.