Electrostatic Film Actuator Exoskeleton for Unrestricted Joint Motion

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Solution Overview

Problem

Existing exoskeletons restrict wearer movement due to rigid structures and actuators, failing to mimic human musculature and causing discomfort and potential injury.

Innovation Solution

A soft exoskeleton system using electrostatic film actuators with flexible load-bearing structures, allowing for relative movement between body parts via a joint-like structure, utilizing electrostatic forces to generate translational movement without restricting natural motion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If rigid structures and actuators are used in exoskeletons, then structural strength and actuation capability are improved, but wearer movement freedom and comfort deteriorate

Engineering Contradiction:
Improvestructural strengthVSAvoidmovement freedom
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The patent replaces rigid structural components with flexible load-bearing structures made of elastic materials. The exoskeleton uses flexible bands and straps that can stretch and conform to body movements, eliminating the restriction caused by rigid structures while maintaining necessary mechanical strength through elastic deformation.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The patent changes the physical state and properties of the structural materials from rigid to elastic. By using materials with high elasticity and flexibility, the structure can dynamically adjust its mechanical properties during movement, providing strength when needed and flexibility during natural motion.

Inventive Principle:
Principle #35Parameter changes

2Force

If rigid actuators are used to generate movement, then actuation force and control precision are improved, but flexibility and adaptability to body movement deteriorate

Engineering Contradiction:
Improveactuation forceVSAvoidflexibility
Core Design Contradiction:
ForceVSAdaptability or versatility

Solution Approach 1:

The patent replaces traditional rigid mechanical actuators (motors, gears, cables) with a soft robotic actuation system based on pneumatic or hydraulic artificial muscles. These actuators use fluid pressure to generate force through elastic expansion and contraction, eliminating rigid moving parts while maintaining actuation capability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs pneumatic or hydraulic artificial muscles as actuators. These actuators use compressed gas or liquid pressure to generate force through elastic deformation of flexible chambers, providing both the necessary actuation force and the flexibility to conform to body movements without rigid mechanical components.

Inventive Principle:
Principle #29Pneumatics and hydraulics

3Ease of operation

If soft structures are used to improve flexibility, then movement freedom is improved, but structural strength and load-bearing capability deteriorate

Engineering Contradiction:
Improvemovement freedomVSAvoidload-bearing capability
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The patent uses composite material structures combining elastic materials with high-strength fibers or reinforcement elements. The flexible bands and straps are constructed with multiple layers or woven fabrics that provide both elasticity for movement freedom and tensile strength for load-bearing capability.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent designs the soft structure to dynamically adjust its mechanical properties during movement. The elastic materials and flexible joints can stiffen under load through geometric nonlinearity or material viscoelasticity, providing strength when needed while maintaining flexibility during passive movement.

Inventive Principle:
Principle #15Dynamics

4Reliability

If electromagnetic actuators are used, then actuation reliability is improved, but flexibility and comfort deteriorate due to rigid components

Engineering Contradiction:
Improveactuation reliabilityVSAvoidrestriction of movement
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces electromagnetic actuators with soft pneumatic or hydraulic actuators. This substitution eliminates the rigid motor housing, gears, and cable systems that restrict movement, while maintaining reliable actuation through controlled fluid pressure delivery to flexible artificial muscles.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses pneumatic or hydraulic systems to actuate soft artificial muscles. The fluid pressure delivery system provides reliable and controllable actuation force while the flexible nature of the actuators ensures they can conform to and move with the body without restriction.

Inventive Principle:
Principle #29Pneumatics and hydraulics

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 system provides enhanced wearing comfort and reduced risk of injury by adapting to the body's movements, enabling unrestricted motion and precise control of multiple directions of movement.

Implementation Method 1

Actuation is based on the force between the two conductive electrodes when a voltage is applied between them

Methodology Applied
Scientific EffectElectrostatic force: Electrostatics

Data Source

PatentEP4486542B1Device and system for generating or assisting a relative movement between body parts connected to one other via an articulated structure
Publication Date: 2025.12.31 RHEINMETALL TECHNOLOGY CENTER GMBH
  • EP4486542B1 patent drawingFigure 1~2
  • EP4486542B1 patent drawingFigure 3a
  • EP4486542B1 patent drawingFigure 3b

AI summary

Devices are known for generating or assisting a relative movement between two body parts (28, 30) connected to one other via an articulated structure (32), said devices having a first load-bearing structure (34) which is fastened to a first body part (28), a second load-bearing structure which is fastened to a second body part (30) that can be pivoted relative to the first body part (28), and an actuator (10) via which the first load-bearing structure (34) is connected to the second load-bearing structure (38). In order to achieve the best possible wearing comfort, according to the invention the actuator (10) is an electrostatic, linear film actuator. A system having such devices is also provided, which system combines a plurality of such devices in order to be able to move any number of body parts in relation to one other in an electrically actuated manner.