Semi-Active Exoskeleton Joints Using Rheological Fluid Damping
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Solution Overview
Problem
Existing wearable exoskeletons for the upper limb are heavy, complex, and require frequent maintenance, with limited degrees of freedom and a short useful life, making them unsuitable for rehabilitation and everyday use.
Innovation Solution
A semi-active exoskeleton with electro- or magneto-rheological fluid joints that reduce articular stress, feature a modular design with reduced complexity and weight, and provide adjustable resistance through a flow mode configuration, allowing for varied viscosity and resistance modulation using electrodes in a closed circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If active exoskeletons with actuators are used, then movement assistance capability is improved, but weight and device complexity increase
Solution Approach 1:
The patent replaces traditional mechanical actuators (motors, gears, linkages) with an electro-rheological fluid-based semi-active joint system. The fluid's viscosity is electrically controlled to provide movement resistance or assistance, eliminating heavy mechanical actuation components while maintaining movement control capability.
Solution Approach 2:
The patent changes the physical parameter of the joint fluid from fixed viscosity to variable viscosity that can be electrically controlled. By adjusting the electro-rheological fluid's viscosity parameter in response to detected movement, the system provides active assistance or resistance without requiring heavy actuators, thus reducing weight while maintaining operational capability.
2Weight of moving object
If passive exoskeletons without actuators are used, then weight is reduced, but movement control and assistance capability deteriorate
Solution Approach 1:
The patent transforms the joint system from static (fixed viscosity) to dynamic (variable viscosity). The electro-rheological fluid's viscosity can be dynamically adjusted based on detected movement characteristics, enabling the lightweight passive exoskeleton to provide active movement control and assistance when needed, thus maintaining control capability without adding heavy actuators.
3Adaptability or versatility
If electro-rheological fluid joints with rotating contacts are used, then variable resistance is achieved, but wear increases and useful life decreases
Solution Approach 1:
The patent replaces mechanical rotating or sliding contacts with a magnetic field-based control system. The electro-rheological fluid's viscosity is controlled through magnetic fields generated by magnets positioned near the fluid chamber, eliminating mechanical wear components while maintaining variable resistance capability through non-contact magnetic actuation.
4Measurement precision
If complex electrode arrangements are used, then precise viscosity control is improved, but device complexity and constructive difficulty increase
Solution Approach 1:
The patent replaces complex electrical electrode arrangements with a simpler magnetic field-based control system. Magnets are positioned to generate magnetic fields that directly control the electro-rheological fluid's viscosity, eliminating the need for complex electrode configurations, electrical connections, and associated control circuitry, thus reducing construction complexity while maintaining control precision.
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 exoskeleton facilitates rehabilitation and everyday activities by reducing stress and weight, requiring minimal maintenance, with a longer useful life and improved kinematic simplicity, enabling effective support for upper limb rehabilitation and everyday tasks.
Implementation Method 1
the fluid present inside the rotational joint which, being of the electro-rheological type, is used as a damping element with variable rotational stiffness and, in relation to the specific phases required by the therapy, it varies its viscosity, therefore its degree of resistance to rotation, following the presence of an electric field
Implementation Method 2
A semi-active exoskeleton with electro- or magneto-rheological fluid joints that reduce articular stress
Data Source
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AI summary
The present invention relates to the field of wearable robotic devices that physically interact with humans, and in particular refers to a wearable exoskeleton, in particular for the upper limb. The invention refers to an electro- or magneto-rheological fluid type semi- active joint purposely conceived to be used to make the exoskeleton. It comprises a first body and a second body, slidably coupled to each other, with a "flow mode" rotating configuration, which allows to have a fluid flow moved by a pressure gradient induced by the circular movement of a piston in a chamber, with constructive simplicity and decrease of wear.