Complex movements from simple inflatables, thanks to physics

Inflatable actuators that change shape based on injected pressure can be powerful, but their big limitation is that they always deform the same way.

The Kresling pattern, which inspired the design of the actuator.

But taking structural inspiration from origami, the researchers created 3D-printed actuators that show it's possible to obtain complex movements from actuators powered by a single pressure source. How is it done? By making the actuators physically bistable, in a way that does not require additional pressure sources.

The key is a modified design based on the Kresling pattern, with each actuator having a specially designed section (the colored triangles in the image above) which are designed to exit under a certain positive pressure and remain stable after the have done. This section retains its shape until some negative pressure is applied, and the section reappears.

Whether or not this section is extended changes the shape of the actuator, thereby changing the way it deforms. This makes a simple actuator bistable and capable of different movements, using a single source of pressure. Stack a bunch of these actuators, and with careful pressure control, intricate movements become possible. See it in action in two short videos, embedded just below the page break.

Here is a video accompanying the research paper that demonstrates the design of the actuator. These actuators are 3D printed from TPU and PLA. Directly below this is a video of a 12-actuator column demonstrating complex movements, all driven by a single pressure source.

Origami and designs found in our natural world mesh well with robotics in general, and it's fascinating how such simple structural changes can have such significant effects on a design.

[via TechXplore]