Soft Robotic Actuators with Reusable Segmented Cores
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Solution Overview
Problem
Existing methods for fabricating bellows-type soft robotic actuators face challenges such as damage during demolding due to high aspect ratio features, material weakness from two-step molding, and time-consuming dissolvable core processes that leave residues.
Innovation Solution
A method using reusable cores and a vacuum technique to generate a pressure differential for core removal, allowing for complex interior shapes without damage and enabling core reuse, suitable for any molding process with complex features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a core is used to define complex internal cavity shapes during molding, then the actuator can achieve complex interior geometries with high-aspect ratios, but the core becomes damaged and cannot be reused during demolding
Solution Approach 1:
The core is segmented into multiple removable components rather than a single monolithic structure. This allows the core to be disassembled and removed from the molded actuator without damaging either the core or the actuator body, enabling core reuse while maintaining complex internal geometries.
Solution Approach 2:
The core is extracted from the molded actuator through a specialized demolding process that separates the core from the actuator body without damage. This extraction enables the core to be reused for subsequent molding operations while the actuator retains its complex internal cavity shape.
2Shape
If a two-step molding process is used to create bellows-type actuators, then complex bellows structures can be formed, but the material strength is reduced and the structure becomes weaker
Solution Approach 1:
The molding process is merged into a single-step operation where the actuator body and bellows structure are formed simultaneously in one molding cycle. This eliminates the weak interface created by joining separate molded parts, restoring full material strength while maintaining the bellows structure.
3Shape
If dissolvable cores are used to create complex internal shapes, then the cores can be removed without damage, but the process becomes time-consuming and leaves residues
Solution Approach 1:
Instead of using dissolvable cores that require time-consuming dissolution processes, a reusable solid core is used that can be removed intact and reused. This copying approach eliminates the need for dissolvable materials while maintaining the ability to create complex internal shapes, significantly improving manufacturing efficiency and eliminating residues.
4Force
If high operating pressures are used in soft actuators, then sufficient force is generated for gripping, but the actuator longevity is reduced and safety is compromised
Solution Approach 1:
The actuator design incorporates geometric parameter changes that amplify the output force without requiring proportional increases in operating pressure. By optimizing the bellows geometry and cavity shape, the actuator generates sufficient gripping force at lower operating pressures, extending actuator longevity and improving safety.
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 creation of complex interior bladder geometries with high-aspect ratios without damaging the core or actuator body, facilitating efficient and reusable core extraction and reducing material strain, thereby improving actuator longevity and reducing operating pressures.
Implementation Method 1
generating a pressure differential between an exterior surface of the actuator and the internal cavity of the actuator, wherein the external pressure is less than the internal pressure, to expand the actuator cavity
Implementation Method 2
generating a pressure differential includes fluidically isolating the exterior surface of the actuator from the internal cavity and applying a vacuum to the actuator
Data Source
AI summary
A method of making an actuator having a complex internal shape includes providing a core of a shape that defines an internal cavity of an actuator; molding an actuator around the core, wherein the core occupies the internal cavity of the actuator, the cavity having an opening; generating a pressure differential between an exterior surface of the actuator and the internal cavity of the actuator, wherein the external pressure is less than the internal pressure, to expand the actuator cavity; and removing the core through the opening of the expanded actuator cavity.