Textile Hyper-Bending Actuator for Large-Angle Wearable Robotics
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Solution Overview
Problem
Conventional pneumatic actuators used in wearable robots, such as exoskeletons, are limited in achieving large bending angles and high bending stiffness, which is crucial for assisting with a wide range of activities, and face challenges in delivering adequate force while maintaining a small volumetric form factor and comfortable attachment to the body.
Innovation Solution
A hyper-bending actuator design that integrates two textiles with different mechanical properties: a knit-elastic material for longitudinal elongation and a braided mesh for radial expansion, driven by an internal bladder, allowing for controlled bending and increased stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional pneumatic actuators are used in wearable robots, then the devices are lightweight and have high power-to-weight ratios, but they are limited in achieving large bending angles and high bending stiffness
Solution Approach 1:
The actuator employs a composite structure consisting of an inner bladder made of elastomeric material and an outer textile layer with woven or knitted pattern. This composite construction allows the actuator to achieve both high bending stiffness and large bending angles by combining the properties of different materials - the elastomeric bladder provides pressure containment and radial expansion while the textile layer provides structural support and controls bending mechanics
Solution Approach 2:
The actuator utilizes flexible textile layers with specific woven or knitted patterns that allow controlled deformation. The textile structure acts as a flexible shell that can expand radially when pressurized while maintaining bending stiffness, enabling large bending angles without compromising structural integrity
2Force
If conventional pneumatic actuators are designed to deliver adequate force, then the bending stiffness increases, but the volumetric form factor increases and comfort decreases
Solution Approach 1:
The textile layer acts as a flexible shell that efficiently transmits force from the pressurized bladder to the external environment. The woven or knitted structure of the textile provides high force transmission capability while maintaining a thin profile, thus delivering adequate force without significantly increasing actuator volume
Solution Approach 2:
The actuator design changes the mechanical parameters of the textile layer through specific weaving or knitting patterns. By adjusting the textile structure parameters (weave density, thread orientation, material properties), the actuator optimizes the balance between force transmission, bending stiffness, and volumetric efficiency
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 hyper-bending actuator achieves larger bending angles and higher stiffness at lower pressures, effectively transmitting substantial forces for wearable robots, enhancing human motion assistance with improved comfort and efficiency.
Implementation Method 1
a knit-elastic material for longitudinal elongation
Implementation Method 2
a braided mesh for radial expansion
Implementation Method 3
driven by an internal bladder, allowing for controlled bending and increased stiffness
Data Source
AI summary
An apparatus includes an actuator body having an elongated shape with two end-caps on opposite ends, the actuator body defining a cavity within the actuator body, a first material extending between the two end-caps forming a first portion of a wall of the cavity; and a second material extending between the two end-caps, forming a second portion of the wall of the cavity, wherein the two materials have different mechanical responses to longitudinal and radial loading.