Soft Robotic Haptic Interface Variable Stiffness

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Solution Overview

Problem

Existing hand rehabilitation therapies are limited by resource constraints and accessibility, leading to inadequate dosage and lack of motivation, and current robotic devices are costly, bulky, or have a limited range of stiffness due to rigid mechanical designs.

Innovation Solution

A pneumatically-actuated soft robotics-based variable stiffness haptic device with interchangeable sleeves made from highly compliant materials, utilizing 3-D printing and polymer molding, offering adjustable stiffness and customizable for clinical and home use, with open-loop or closed-loop control systems for enhanced rehabilitation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If rigid mechanical designs are used for variable stiffness actuators, then the device structure is stable and controllable, but the range of stiffness is limited and the device becomes bulky

Engineering Contradiction:

Improverange of stiffnessVSAvoiddevice size

Core Design Contradiction:

Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

The patent replaces rigid mechanical variable stiffness actuators with a soft robotic haptic device that uses pneumatic pressure control and interchangeable sleeves to achieve variable stiffness. This substitution eliminates bulky mechanical components while expanding the stiffness range through material compliance variations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the stiffness parameter by using interchangeable sleeves made of different materials with varying stiffness properties, rather than relying on mechanical adjustments. This allows continuous variation of stiffness within a broader range without increasing device volume.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If multiple objects of varying stiffness are used for rehabilitation training, then the training intensity can be adjusted, but the device complexity and cost increase

Engineering Contradiction:

Improvetraining intensity adjustmentVSAvoidnumber of components

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent creates a single universal haptic device that can perform multiple rehabilitation training functions by simply changing the interchangeable sleeve. This eliminates the need for multiple separate objects while maintaining the ability to adjust training intensity through different sleeve materials.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent segments the haptic device into modular components, specifically the interchangeable sleeve that can be easily swapped. This segmentation allows the system to offer multiple stiffness options without requiring multiple complete devices, reducing overall complexity.

Inventive Principle:

Principle #1Segmentation

3Ease of operation

If traditional physical therapy methods are used for hand rehabilitation, then the treatment is simple and accessible, but the dosage is inadequate and patient motivation is low

Engineering Contradiction:

Improvetreatment accessibilityVSAvoidrehabilitation dosage

Core Design Contradiction:

Ease of operationVSProductivity

Solution Approach 1:

The patent enables patients to perform self-directed rehabilitation exercises using the haptic device at home. The device provides automated resistance and feedback, allowing patients to independently complete high-repetition training protocols that would be difficult to achieve with traditional therapy alone.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent changes the rehabilitation approach by providing programmable, adjustable resistance levels and training parameters that can be precisely controlled and monitored, enabling higher dosages of repetitive exercise compared to traditional fixed-protocol physical therapy.

Inventive Principle:

Principle #35Parameter changes

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 device provides a cost-effective, adaptable, and perceivable range of stiffness, effectively aiding hand rehabilitation by enhancing motivation and progressive intensity, with 68% of users correctly matching stiffness settings, demonstrating improved rehabilitation efficacy.

Implementation Method 1

a pneumatic actuator in communication with the cavity and configured to provide pressure to the cavity

Methodology Applied

Scientific EffectPneumatic pressure: Pressure Increase

Implementation Method 2

a plurality of grooves configured to receive a fiber wound around the outer wall

Methodology Applied

Scientific EffectTensile strength of fiber: Tension

Data Source

PatentUS11446545B2Soft robotic haptic interface with variable stiffness for rehabilitation of sensorimotor hand function

Publication Date: 2022.09.20 THE ARIZONA BOARD OF REGENTS ON BEHALF OF THE UNIV OF ARIZONA

AI summary

A pneumatically-actuated soft robotics-based variable stiffness haptic interface device for rehabilitation of a hand includes a body having a flexible outer wall and a cavity defined by the outer wall, the outer wall including a plurality of grooves configured to receive a fiber wound around the outer wall. The device further includes a pneumatic actuator in communication with the cavity and configured to provide pressure to the cavity.