Composite Sheet Actuator With Reversible Jamming Stiffness
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Solution Overview
Problem
Current jamming actuators in soft robotics lack the ability to rapidly and reversibly switch their tensile modulus, and existing solutions face limitations such as slow switching times or negligible work done during jamming, which restricts their application in strain limiting layers for soft robots.
Innovation Solution
The development of an actuator comprising two sheets with misaligned high-aspect-ratio openings that can switch from a low-stiffness state to a high-stiffness state through mechanisms like pneumatic, magnetic, or adhesive jamming, allowing for rapid and reversible changes in stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional jamming actuators are used, then stiffness change is achieved, but switching time is slow and work done during jamming is negligible
Solution Approach 1:
The actuator is segmented into multiple discrete elements (sheets with openings) that can independently jam together. This segmentation allows rapid engagement of individual elements rather than requiring simultaneous jamming of a continuous structure, thereby increasing switching speed while maintaining effective work output.
Solution Approach 2:
The actuator transitions from a static jammed state to a dynamic reversible jamming process. The misaligned openings enable the structure to dynamically adjust its stiffness by controlling the engagement of individual sheet elements, allowing rapid switching between states with sufficient work output for strain limiting applications.
2Strength
If sheets are stacked with misaligned openings for jamming, then stiffness increases up to 1000 times, but the structure becomes more complex
Solution Approach 1:
The actuator uses thin sheet structures with patterned openings instead of bulky rigid components. These flexible sheets can be easily stacked and aligned, achieving high stiffness ratios through their geometric design rather than material properties or complex mechanisms, thereby maintaining structural simplicity while achieving up to 1000x stiffness increase.
Solution Approach 2:
The actuator creates a composite structure by stacking multiple sheets with different opening patterns. This composite approach achieves high stiffness through the combined geometric interlocking of misaligned openings rather than requiring complex individual components, simplifying the overall structure while maximizing strength.
3Adaptability or versatility
If rapid and reversible stiffness switching is implemented, then application in soft robots is enabled, but control mechanisms become more complex
Solution Approach 1:
The actuator structure itself provides the jamming mechanism through its geometric design. The misaligned openings automatically engage when sheets are pressed together, eliminating the need for external actuators or complex control mechanisms. This self-jamming capability enables rapid reversible stiffness switching while maintaining simple control, expanding applicability in soft robots.
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 actuator achieves a significant increase in stiffness, up to 1000 times, enabling efficient strain limiting and shape change in soft robots, with the ability to rapidly switch between states and maintain deformation, addressing the limitations of existing technologies.
Implementation Method 1
the first and second sheets are magnetically attractive to each other in the second state such that the first and second sheets are jammed together
Implementation Method 2
the first and second sheets are adhered together in the second state such that the first and second sheets are jammed together
Implementation Method 3
the sleeve enclosing the first and second sheets and connected to a vacuum; wherein the sleeve is under vacuum at the second state
Data Source
AI summary
An actuator is described, including a first sheet comprising a plurality of first openings,; and a second sheet comprising a plurality of second openings; wherein the first and second sheets are stacked together such that at least one of the first and second openings are misaligned; and the actuator is configured to move from a first state to a second state, wherein in the first state, out-of-plane motion of the first and second sheets is permitted; and in the second state, the first and second sheets as well as the misaligned first and second openings are jammed together to restrict the out-of-plane motion of the first and second sheets. Methods of actuating and making such actuator are also described.