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American Association for the Advancement of Science

A real-life, origami-inspired transformer

The self-folding crawling robot in three stages - profile view.
[Credit: Seth Kroll, Wyss Institute]

Using flat materials and origami-inspired patterns, researchers have built a real-life transformer -- a self-folding robot that, once assembled, can crawl and turn. This advance is reported in the 8 August issue of the journal Science. Such a self-folding machine has various potential applications, including delivery to tight spaces, like rooms in collapsed buildings, for search and rescue missions.

In a related report in the same issue, researchers show how they used origami-based engineering to design a lightweight, ultra-tough material with adjustable properties. Putting such materials into machines could be used to improve their function, the researchers say.

The process of self-assembly happens all around us; biological molecules form structures like viruses without guidance from an outside source, and insects in colonies build nests in the same way.

Several types of self-assembly are applicable to engineering. One is the self-organization of flat materials, like paper, into 3-D ones, like robots. This type of self-assembly is particularly useful since it can yield complex shapes that can be built at all different sizes and that are very strong for their low weight.

However, existing approaches to build self-folding machines have not yet lead to machines that can self-fold and then function say, to move, or to compute something without outside human help. (A human must be present to remove a scaffold that supported the robot while it was building, for example.)

Such robots would be very valuable if they could be created because they could be shipped flat in large quantities to do various types of work.

Now, S. Felton of Harvard's Wyss Institute for Biologically Inspired Engineering and his team together make a leap forward demonstrating a method for building a self-folding robot that crawls.

The researchers built their robot with easy-to-find materials, including a clear, flat, hard substance called a polymer that was designed to fold at 100C. They also used self-folding hinges.

The placement of the hinges in the polymer, as well as the order in which they were triggered to fold (by heat-generating circuits), yielded a complex 3-D machine.

To automate the folding process, the researchers used 3-D origami design software that generated detailed crease patterns in the polymer.

After their robot folded itself into shape, it walked, and it was also able to turn.

The work shows a practical process for building self-assembling machines. Since it is relatively easy to implement, the authors say, it can be adapted to a wide range of applications.

In a related report, Cornell University's Jesse Silverberg and colleagues studied a specific type of zigzag origami fold that has been used to pack solar panels for space missions.

The researchers used this pattern to create folded sheets and then, by adding or removing defects, came up with a way to structurally alter these sheets to control their mechanical properties.

This approach will allow scientists to create metamaterials with desirable characteristics, such as strength or stiffness. By extending the approach to self-folding robotic systems, like the one described above, this work paves the way for machines that can speedily switch up their functionality.

A Perspective provides additional insights into both reports.