Coiled Fluid Actuator With Resistance Sensing for Long Extension
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Solution Overview
Problem
Soft fluid-driven actuators face limitations in the distance they can extend due to the efficient storage of material needed to enclose the fluid volume as it expands, with existing mechanisms typically limited by the thickness of folds in bellows-like structures and contraction ratios in fiber-reinforced actuators.
Innovation Solution
A self-sensing actuator with a coiled section that expands via pressurized fluid, featuring conductive layers to form an internal electrical junction, allowing for the measurement of resistance to determine the length of the expanded section and control fluid addition to achieve desired lengths, and a method of fabrication involving shifting and bonding backing layers to create a sealed coiled configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If bellows-like structures with folds are used to enclose fluid volume, then the actuator can extend, but the extension distance is limited by the thickness of the folds
Solution Approach 1:
The patent applies a coiled or spiral configuration instead of traditional bellows folds, transforming the linear extension problem into a rotational/uncoiling motion. This curved geometry allows the actuator to achieve much longer extension distances by uncoiling the spiral structure, effectively removing the thickness limitation inherent in flat-fold bellows designs.
Solution Approach 2:
The invention transitions from a two-dimensional fold-based expansion to a three-dimensional coiled structure that can uncoil along its length. This dimensional change enables the actuator to extend beyond the constraints of fold thickness by utilizing the spiral geometry's inherent length advantage when uncoiled.
2Strength
If fiber-reinforced actuators are used, then structural strength is improved, but the contraction ratio is limited
Solution Approach 1:
The coiled configuration provides inherent structural strength through its spiral geometry, eliminating the need for heavy fiber reinforcement while maintaining integrity during expansion and contraction. The curved structure naturally resists deformation forces, enabling greater contraction ratios without compromising strength.
Solution Approach 2:
The patent utilizes flexible coiled walls or thin film structures that can dramatically contract and expand without requiring rigid fiber reinforcement. This flexible shell approach enables higher contraction ratios by allowing the structure to collapse more completely while maintaining structural integrity through its coiled geometry rather than fiber support.
3Measurement precision
If conductive layers are added for sensing, then length measurement capability is improved, but device complexity increases
Solution Approach 1:
The patent combines the structural wall or skin of the actuator with conductive layers, merging the enclosing function with the sensing function. This integration allows length measurement through resistance changes in the conductive layers without adding separate sensing components, thereby improving measurement precision while minimizing increases in device complexity.
Solution Approach 2:
The conductive layers serve multiple functions: they provide structural integrity as part of the actuator wall, enable length measurement through resistance sensing, and can potentially serve as heating elements or signal transmission paths. This multi-functionality improves measurement capability while offsetting the complexity increase through functional consolidation.
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 long extensions by storing the enclosing volume in a roll and allows for precise control of actuator length through resistance measurement feedback, overcoming the limitations of existing actuators in extension distance and contraction ratios.
Implementation Method 1
a coiled section configured to be expanded into an expanded section via addition of a pressurized fluid through a fluid inlet
Implementation Method 2
one or more conductive layers configured to form an internal electrical junction at a point of transition between the coiled section and expanded section, wherein a length of the expanded section is configured to be determined by measuring a resistance of a circuit formed by the one or more conductive layers
Data Source
AI summary
Systems, devices, and methods for a self-sensing fluid-driven extending actuation device and associated methods where a fluid controller adds fluid into or removes fluid from a coiled device made from sealed flat layers of material; the pressurized fluid expands the internal volume of the layers causing the device to partially un-coil and extend; a resistance measurement circuit measures the length of the extended section and uses it to control the fluid added or removed from the device to achieve a desired length.