Variable-Stiffness Soft Actuator Hinge for Inflation and Load Stages
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Solution Overview
Problem
Soft actuators in robotics and other applications require a variable stiffness to adapt to different operational stages, but existing technologies lack efficient mechanisms to dynamically adjust stiffness in response to inflation and loading conditions.
Innovation Solution
A soft actuator with a variable-stiffness hinge that includes an inflatable chamber and jamming surfaces, where the stiffness is decreased during inflation and increased when fully inflated, utilizing active materials or electrostatic clutches to adjust friction and stiffness accordingly, and a computing device to control these changes based on operational conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the hinge uses a fixed stiffness structure, then the manufacturing is simple, but the actuator cannot adapt to different operational stages (inflation and loading)
Solution Approach 1:
The hinge transitions from a static fixed-stiffness structure to a dynamic variable-stiffness structure that can adjust its mechanical properties in real-time. The hinge includes adjustable components (such as springs with variable stiffness or movable joints) that allow the stiffness to be modified during operation, enabling the actuator to adapt to different operational stages including inflation and loading phases.
Solution Approach 2:
The hinge structure incorporates mechanisms that allow changing the stiffness parameter dynamically. This may involve adjusting preloads on springs, changing the engagement state of mechanical elements, or modifying the geometric configuration of the hinge components to achieve different stiffness levels suitable for various operational conditions.
2Strength
If the hinge stiffness is increased for loading stage, then the loading capacity improves, but the deformation flexibility during inflation stage deteriorates
Solution Approach 1:
The hinge employs dynamic stiffness adjustment mechanisms that allow the structure to be flexible during inflation (enabling easy deformation) and stiff during loading (providing high loading capacity). This is achieved through components like progressive springs, variable geometry joints, or actively controlled mechanical elements that respond to operational conditions.
Solution Approach 2:
The hinge stiffness is periodically adjusted to match the operational cycle of the actuator. During the inflation phase, the hinge maintains lower stiffness to allow deformation; during the loading phase, it transitions to higher stiffness to support loads. This periodic adjustment aligns the mechanical properties with the operational requirements at each stage.
3Ease of operation
If the hinge stiffness is decreased for inflation stage, then the deformation flexibility improves, but the loading capacity in inflated stage deteriorates
Solution Approach 1:
The hinge uses dynamic stiffness control to provide low stiffness during inflation for maximum deformation flexibility, then transitions to high stiffness during the loading stage to ensure adequate loading capacity. This dynamic adjustment prevents the compromise that would exist with a fixed-stiffness design.
Solution Approach 2:
The hinge structure is prepared in advance with mechanisms that enable stiffness adjustment before the loading stage begins. During inflation, the hinge maintains a compliant state; before loading occurs, the stiffness is pre-adjusted to the higher level needed for load bearing, ensuring optimal performance without sacrificing flexibility during the inflation phase.
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 the soft actuator to effectively change stiffness in response to inflation stages, allowing for flexible deformation during inflation and increased loading capacity in the fully inflated state, enhancing its operational versatility and reliability.
Implementation Method 1
The inflation chamber is inflatable during an inflation stage, in which the second end rotates toward the first end about a folding axis
Implementation Method 2
In the inflated stage, the jamming surfaces are pressed together to increase the stiffness of the hinge
Data Source
AI summary
A soft actuator includes an inflation chamber. The inflation chamber has a first end and a second end opposite the first end. The inflation chamber is inflatable during an inflation stage, in which the second end rotates toward the first end about a folding axis, and is operable to be loaded during an inflated stage, in which the inflation chamber is inflated. The soft actuator also includes a variable-stiffness hinge located between the first end and the second end along the folding axis. The variable-stiffness hinge has a decreased stiffness in the inflation stage and an increased stiffness in the inflated stage.