Sliding Tendon Elastomer Actuators for Geometry and Stiffness Control

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Solution Overview

Problem

Rigid robotic structures are prone to critical failure under high stress disturbances and traditional actuators fail to effectively drive motion in soft structures, lacking the ability to change shape and material properties.

Innovation Solution

A tendon-driven, fiber-reinforced elastomer membrane with non-bonded tendons embedded in an elastomer matrix, allowing for geometric and stiffness control through tension application.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If rigid structures are used to maintain strength and stability, then structural strength is improved, but the structure becomes prone to critical failure under high stress disturbances and cannot accommodate perturbations

Engineering Contradiction:

Improvestructural strengthVSAvoidresilience to disturbance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent employs soft, flexible elastomeric structures with embedded fiber arrays that can bend and deform under stress. The flexible membrane structure allows the system to accommodate disturbances through controlled deformation rather than rigid resistance, preventing critical failure while maintaining structural integrity.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The invention creates a composite structure combining elastomer matrix material with embedded fiber arrays. This composite provides both the flexibility needed to accommodate disturbances and the reinforcement necessary for structural strength, resolving the contradiction between rigidity and resilience.

Inventive Principle:

Principle #40Composite materials

2Force

If traditional rigid actuators are used to drive motion, then actuation force is provided, but they fail to effectively drive motion of soft structures due to relying on transmitting large torques through small contact points

Engineering Contradiction:

Improveactuation forceVSAvoideffectiveness in driving soft structure motion

Core Design Contradiction:

ForceVSEase of operation

Solution Approach 1:

The patent replaces traditional rigid mechanical actuators with a tendon-driven system using flexible cables or tendons that pass through the soft structure. This substitution allows force transmission through distributed contact along the tendon length rather than through small contact points, enabling effective actuation of soft structures.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The tendon acts as an intermediary element between the actuation source and the soft structure. The tendon transmits force through the elastomeric material without requiring direct mechanical coupling, allowing effective actuation while maintaining the soft structure's flexibility.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Strength

If tendons are mechanically bonded to the elastomer matrix material, then structural integrity is improved, but the tendons cannot move through the elastomer matrix material to enable geometric control

Engineering Contradiction:

Improvestructural integrityVSAvoidgeometric control capability

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The invention extracts the bonding interface between tendons and elastomer matrix, creating a deliberate separation that allows tendon movement. The tendons are embedded in the elastomeric material without mechanical bonding, enabling them to slide and reposition within the matrix to achieve geometric control while maintaining sufficient structural integrity through the embedding relationship.

Inventive Principle:

Principle #2Taking out (Extraction)

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 flexible structures to accommodate disturbances and return to operational states, providing controllable geometry and stiffness adjustments.

Implementation Method 1

soft, flexible structures may be capable of bending and thus may accommodate such a disturbance and return to an operational state

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

a fiber array embedded within the elastomer matrix material, wherein: the fiber array comprises one or more tendons

Methodology Applied

Scientific EffectFiber reinforcement: Composite Materials

Implementation Method 3

the one or more tendons are not mechanically bonded to the elastomer matrix material such that the one or more embedded tendons are able to move through the elastomer matrix material

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS12496706B2Sliding tendons for high-strain elastomer actuators

Publication Date: 2025.12.16 UNIV OF FLORIDA RESEARCH FOUNDATION INC

AI summary

A soft structure fiber reinforcement and actuation technology is provided. In an example embodiment, the tendon-driven, fiber-reinforced elastomer membrane comprises an elastomer matrix material and a fiber array embedded within the elastomer matrix material. The one or more tendons are not mechanically bonded to the elastomer matrix material, such that the one or more embedded tendons are able to move through the elastomer matrix material. One or more apparatuses may employ one or more such tendon-driven, fiber-reinforced elastomer membranes for use in a variety of applications.