Bistable Elastomeric Actuator With Frustum Snap-Through
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Solution Overview
Problem
Fluid-driven soft actuators have slow actuation speeds, limiting their efficiency and applications.
Innovation Solution
A bistable elastomeric actuator design featuring pairs of frustums with different base angles and a soft folding hinge, integrated with silicone and polyethylene terephthalate (PET) components, allowing for fast actuation and mechanical compliance through a novel fabrication method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fluid-driven soft actuators are used, then mechanical compliance and softness are achieved, but actuation speed becomes slow
Solution Approach 1:
The actuator body is segmented into multiple frustum pairs (at least two pairs), where each frustum pair can snap independently. This segmentation allows the actuator to achieve rapid discrete elongation through sequential snap-through of individual frustum pairs, significantly increasing actuation speed while preserving overall mechanical compliance
Solution Approach 2:
The actuator utilizes dynamic snap-through behavior of bistable frustum structures. Each frustum pair transitions between two stable states through a rapid snap-through motion when triggered by fluid pressure, enabling fast actuation speeds (up to 1.5 m/s) while maintaining the soft, compliant nature of the elastomeric material
2Speed
If frustum pairs with different base angles are used, then fast snapping action is achieved, but manufacturing complexity increases
Solution Approach 1:
Each frustum pair consists of two thin frustum shells with different base angles (one with larger base angle, one with smaller base angle). This asymmetric geometry creates the bistable snap-through behavior necessary for fast actuation. The asymmetric design is integrated into the molding process, where the frustums are molded with embedded thermoplastic polymer structures that define the different base angles, making the complex geometry manufacturable through standard molding techniques
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 maximum extension ratio of 0.58, snapping speed of 1.5 m/s, and output force of 48N, enabling efficient and rapid elongation and retraction.
Implementation Method 1
The soft folding hinge may include an elastomer. In various embodiments, a portion of the thin frustum shell configured with a large base angle may be shaved off and replaced by an elastomer.
Implementation Method 2
The body may be configured to receive a fluid to extend the actuator. The body may be configured to remove a fluid to contract the actuator.
Data Source
AI summary
Elastomeric actuators and methods of making the same are provided herein. In some examples, an actuator includes a body comprising a plurality of pairs of frustums, wherein the body is configured to receive a fluid to extend the actuator and to remove the fluid to contract the actuator. In some examples, each pair of frustums includes two thin frustum shells sharing a common base circle diameter.