Multi-Cell MR Fluid Elastomer for Independent Stiffness Control

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Solution Overview

Problem

Existing devices using magnetorheological (MR) fluids primarily utilize shear-flow magnetorheology mode for impedance modulation and torque generation, limiting the integration of squeeze-flow mode for independent impedance modulation and torque control in robotic prostheses.

Innovation Solution

Integration of multi-cell MR-fluid elastomer compounds with independently operable magnetic field inductors to vary stiffness through squeeze-flow mode, allowing separate impedance modulation and torque control in robotic prostheses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If shear-flow magnetorheology mode is used for impedance modulation and torque generation, then device structure is simplified, but independent impedance modulation and torque control are limited

Engineering Contradiction:

Improvedevice structureVSAvoidindependent impedance modulation and torque control

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The device is divided into multiple independent cells, each capable of independent impedance modulation through individual magnetic field inductors. This segmentation allows each cell to be controlled independently for torque generation while the collective arrangement enables independent impedance modulation, resolving the contradiction between structural simplicity and control versatility.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The magnetic field inductors are designed to serve dual functions: generating torque through shear-flow magnetorheology and modulating impedance through squeeze-flow magnetorheology. This multi-functionality allows a single device structure to achieve both independent torque control and independent impedance modulation, eliminating the need for separate control systems.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If multi-cell MR-fluid elastomer compounds with independent magnetic field inductors are integrated, then independent impedance modulation and torque control are enabled, but device complexity increases

Engineering Contradiction:

Improveindependent impedance modulation and torque controlVSAvoiddevice structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Multiple magnetic field inductors are merged into a single integrated device structure with shared housing and fluid pathways. The inductors work cooperatively through the MR fluid medium, allowing independent control of each cell while maintaining a unified device architecture. This merging approach enables versatile control functionality without proportionally increasing overall device complexity.

Inventive Principle:

Principle #5Merging (Combining)

3Ease of operation

If squeeze-flow mode is utilized for stiffness variation, then stiffness control is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvestiffness controlVSAvoidmanufacturing process

Core Design Contradiction:

Ease of operationVSEase of manufacture

Solution Approach 1:

The device employs flexible elastomeric membranes as cell walls that can deform under magnetic field-induced stiffness changes. These flexible shells accommodate the squeeze-flow mode operation by allowing volume changes and shape adjustments without requiring complex rigid mechanical structures, thereby simplifying manufacturing while enabling precise stiffness control.

Inventive Principle:

Principle #30Flexible shells and thin films

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 described devices achieve a maximum stiffness increase of at least two-fold and improved torque control, enabling effective impedance modulation across multiple degrees of freedom.

Implementation Method 1

The MR fluid within the at least one cell cavity can further be operable to vary a stiffness of the at least one cell cavity in response to the magnetic field

Methodology Applied

Scientific EffectMagnetorheological effect: Magnetorheological Fluid

Implementation Method 2

a magnetic field inductor can be positioned adjacent to at least one of the cell cavities. The magnetic field inductor can be selectively operable to vary a magnetic field

Methodology Applied

Scientific EffectMagnetic field induction: Electromagnetic Induction

Data Source

PatentUS12422016B2Magnetorheological fluid cell systems and methods

Publication Date: 2025.09.23 PURDUE RES FOUND

AI summary

A magnetorheological apparatus includes a flexible body formed of an elastomer material, a plurality of cell cavities defined by the flexible body, a magnetorheological (MR) fluid disposed within each cell cavity of the plurality of cell cavities, and a magnetic field inductor positioned adjacent to at least one of the cell cavities. Each cell cavity of the plurality of cell cavities is fluidly encapsulated within the flexible body. The magnetic field inductor is selectively operable to vary a magnetic field, and the MR fluid within the at least one cell cavity is configured to vary a stiffness of the at least one cell cavity in response to the magnetic field.