Textile Actuator Geometry With Built-In Joint Overextension Stops
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Solution Overview
Problem
Traditional electro-magnetic and rigid hydraulic actuators are heavy, costly, and restrictive, lacking the flexibility and comfort needed for wearable robotic applications, particularly in assisting human movements and providing support for body segments.
Innovation Solution
Development of textile actuators with a fluid-impermeable bladder or structure integrated into a textile envelope, allowing for non-linear displacement and mechanical stops to prevent excessive movement, enabling lightweight, comfortable, and non-restrictive wearable robots that can assist body segments through fluid pressure changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If traditional electro-magnetic or rigid hydraulic actuators are used, then actuation force and reliability are improved, but weight and device complexity increase, making them unsuitable for wearable applications
Solution Approach 1:
The patent employs pneumatic actuation using a bladder that expands when pressurized with gas or liquid. This soft fluidic approach replaces heavy electro-magnetic or rigid hydraulic actuators, providing sufficient actuation force while dramatically reducing weight. The bladder expands to push against the textile envelope, generating the necessary force for joint assistance without the mass of traditional actuators.
Solution Approach 2:
The patent uses a flexible textile envelope with a bladder inside to create a soft actuator. The textile envelope acts as a flexible shell that constrains the bladder expansion and translates it into useful mechanical motion. This flexible structure replaces rigid actuator components, reducing weight while maintaining actuation capability through the compliance of the textile and bladder system.
2Weight of moving object
If soft fluidic actuators are used, then weight and compliance are improved, but control precision and reliability deteriorate due to lack of mechanical stops
Solution Approach 1:
The patent incorporates mechanical stops directly into the textile envelope structure during manufacturing. These stops are pre-positioned to limit the expansion of the bladder, preventing over-displacement of the actuator. By building the mechanical constraints into the envelope's geometry from the start, the system maintains reliability and control precision without adding complex active control mechanisms.
Solution Approach 2:
The textile envelope serves as a flexible shell that not only contains the bladder but also provides mechanical stops through its geometric design. The envelope's structure includes features like folded sections, seams, or integrated rigid elements that create hard limits on expansion. This dual function of the flexible shell—containing pressure and providing mechanical constraints—maintains control precision while keeping the actuator lightweight and compliant.
3Reliability
If textile actuators with mechanical stops are used, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent merges the functions of the bladder, envelope, and mechanical stops into a single integrated textile structure. The mechanical stops are not separate components but are formed as integral parts of the textile envelope's geometry. This consolidation reduces the number of discrete parts and assembly steps, maintaining reliability through built-in mechanical constraints while avoiding the complexity of multi-component systems with separate stops and actuators.
Solution Approach 2:
The textile envelope serves multiple functions simultaneously: it contains the bladder, provides structural support, and creates mechanical stops through its geometric design. By using the flexible shell to perform these combined roles, the patent avoids adding separate mechanical stop components that would increase device complexity. The stops emerge from the envelope's construction rather than being added as separate elements.
4Ease of manufacture
If extensible textile envelopes are used, then ease of manufacture is improved, but control precision deteriorates due to stretching during actuation
Solution Approach 1:
The patent employs a substantially inextensible textile envelope that maintains its geometric shape during actuation. This envelope acts as a rigid constraint that prevents stretching, ensuring that bladder expansion translates predictably into actuator displacement. The inextensible nature of the envelope provides precise control over the actuator's motion, maintaining manufacturing precision while still allowing the actuator to be fabricated using textile construction methods.
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 textile actuators provide efficient and comfortable assistance to body segments, allowing for complex motions while being lightweight and easy to use, offering a solution for muscle weakness and fatigue without the stigma of traditional assistive devices.
Implementation Method 1
A textile actuator worn by a user comprises a textile envelope that defines a chamber made fluid-impermeable by a fluid-impermeable bladder contained in the textile envelope and/or a fluid-impermeable structure incorporated into the textile envelope
Implementation Method 2
A fluid is delivered into or out of the chamber to displace the textile envelope primarily by transitioning from an uninflated state to the pre-determined geometry due to displacement of the textile envelope
Data Source
AI summary
A textile actuator worn by a user comprises a textile envelope that defines a chamber made fluid-impermeable by a fluid-impermeable bladder contained in the textile envelope and/or a fluid-impermeable structure incorporated into the textile envelope. The textile envelope has a pre-determined geometry that produces an equilibrium state at a non-180-angle displacement and that stops further displacement upon pressurization of the chamber and prevents over-extension the joint. A fluid is delivered into or out of the chamber to displace the textile envelope primarily by transitioning from an uninflated state to the pre-determined geometry due to displacement of the textile envelope rather than via stretching or contraction of the textile envelope. When actuated, the textile actuator (a) displaces a body segment of the user and/or (b) supports and holds the body segment of the user in place.