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Harvard researchers have developed a new group of origami-based, battery-free robots that are powered and controlled through a wireless magnetic field.

Origami folding robots have emerged as an exciting new frontier of robotic design, but these generally require onboard batteries or a wired connection to a power source, making them bulkier and clunkier.

The Harvard researchers from the Wyss Institute and Harvard SEAS hope to remedy this with their new bots which are flat and thin plastic tetrahedrons, with the three outer triangles connected to the central triangle by hinges, and a small circuit on the central triangle.

Attached to the hinges are coils made of a type of metal called shape-memory alloy (SMA) that can recover its original shape after deformation by being heated to a certain temperature.

When the robot’s hinges lie flat, the SMA coils are stretched out in their “deformed” state; when an electric current is passed through the circuit and the coils heat up, they spring back to their original, relaxed state, contracting like tiny muscles and folding the robots’ outer triangles in toward the center. When the current stops, the SMA coils are stretched back out due to the stiffness of the flexure hinge, thus lowering the outer triangles back down.

The power that creates the electrical current needed for the robots’ movement is delivered wirelessly using electromagnetic power transmission – the same technology that recharges cell phones batteries and other small electronics.

According to the researchers, an external coil with its own power source generates a magnetic field, which induces a current in the circuits in the robot, thus heating the SMA coils and inducing folding.

In order to control which coils contract, the team built a resonator into each coil unit and tuned it to respond only to a very specific electromagnetic frequency. By changing the frequency of the external magnetic field, they were able to induce each SMA coil to contract independently from the others.

Just like the muscles in the human body, the SMA coils can only contract and relax: it’s the structure of the robot’s body  – the origami “joints” – that translates those contractions into specific movements.

Image, video and content: Wyss Institute for Biologically Inspired Engineering

https://player.vimeo.com/video/224701422?title=0&byline=0&portrait=0

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