Soft Actuator Motion Customization via Conforming Sleeves

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Solution Overview

Problem

Existing soft actuators lack the ability for 'on-the-fly' modification of output motions, connection interfaces, and surface properties, which is crucial for immediate customization in applications like robotic manipulation and rehabilitation where patient needs vary.

Innovation Solution

Mechanically programmed soft actuators with a soft actuator body that can bend, extend, contract, or twist, combined with a conforming sleeve that constrains the actuator body to alter its motion, allowing for rapid modification of its behavior and integration with various interfaces and sensors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If soft actuators are fabricated using CAD programs and 3D printers, then iteration of mold designs is relatively fast (on the order of days), but on-the-fly modification of actuator output motions, connection interfaces, and surface properties is not allowed

Engineering Contradiction:

Improveiteration speed of mold designsVSAvoidability to modify actuator motions on-the-fly

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The actuator system is segmented into a monolithic soft actuator body and separate conforming sleeves. The sleeves can be independently added, removed, or modified without re fabricating the entire actuator, enabling rapid reconfiguration of motion patterns while maintaining the integrity of the base actuator structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The conforming sleeves provide dynamic reconfigurability to the actuator system. By changing which sleeves are applied to which portions of the actuator body, the output motions can be dynamically modified on-the-fly to match varying task requirements, patient needs, or application scenarios.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If conforming sleeves are wrapped around the soft actuator body to constrain bending, then the actuator can be rapidly reconfigured for different motions, but the device complexity increases

Engineering Contradiction:

Improveability to rapidly reconfigure actuator motionVSAvoidcomplexity of actuator system with sleeves

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The conforming sleeves are implemented as flexible thin-walled structures that conform to the surface of the soft actuator body. These sleeves are simple to manufacture and apply, providing motion constraint functionality without adding significant structural complexity to the overall system.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The conforming sleeves serve multiple functions: they constrain bending in specific regions, define connection interfaces, modify surface properties, and enable rapid reconfiguration. This multi-functionality reduces the need for multiple specialized components, thereby managing system complexity while enhancing adaptability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If the soft actuator body is constrained by the sleeve to bend only where not covered, then customization of actuator motion is enabled, but manufacturing precision requirements increase

Engineering Contradiction:

Improvecustomization capability of actuator motionVSAvoidprecision required for sleeve placement

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The system enables customization of actuator motion by changing which parameters (sleeve positions, sleeve types, sleeve materials) are modified rather than re manufacturing the entire actuator. This approach allows for precise motion customization through selective parameter changes in the sleeve configuration rather than requiring high precision in the base actuator manufacturing.

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

Enables safe human-robot interaction, comfortable interaction with soft tissues, and versatile use in robotic assistance, grippers, and toys, with the ability to rapidly customize actuator motion and capabilities, enhancing usability and safety.

Implementation Method 1

fluid (e.g., air or liquid) is pumped into a chamber defined by the soft actuator body, causing the soft actuator body to bend where the soft actuator body is not covered by the sleeve

Methodology Applied

Scientific EffectFluid pressure: Pressure Increase

Implementation Method 2

the soft actuator body is configured to bend, linearly extend, contract, twist or combinations thereof when actuated without constraint

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 3

at least one conforming sleeve wrapped around part of the soft actuator body and configured to constrain the soft actuator body inside the sleeve when actuated

Methodology Applied

Scientific EffectMechanical constraint: Physical Containment

Data Source

PatentEP3058237B1Mechanically programmed soft actuators with conforming sleeves

Publication Date: 2020.12.02 PRESIDENT & FELLOWS OF HARVARD COLLEGE

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AI summary

A mechanically programmed actuator includes at least one soft actuator body configured to bend, linearly extend, contract, twist, or combinations thereof when actuated without constraint; an activation mechanism (e.g., a fluid pump) configured to actuate the soft actuator body; and at least one sleeve wrapped around part of the soft actuator body and configured to constrain the soft actuator body inside the sleeve when actuated and to cause the soft actuator body to deform where not covered by the sleeve.