3D printer produces robot that gets up and walks away

This 3-D hexapod robot moves via a single motor, which spins a crankshaft that pumps fluid to the robot’s legs. Besides the motor and battery, every component is printed in a single step with no assembly required.

Robert MacCurdy/MIT CSAIL

It sounds like something out of a science fiction movie like "Blade Runner." But researchers at MIT's Computer Science and Artificial Intelligence Laboratory (CSAIL) have developed a new 3D printing process that creates robots that are fully functional from the moment they come off the printer.

The normal process for creating something complex and mobile like a robot through 3D printing usually involves multiple print runs to make each component. After all the pieces are printed out, then the object needs to be assembled. MIT's new process is significant in that the production period is streamlined, with the robot's solid and liquid hydraulic parts being created in one step, according to a university press release.

A paper on the research was just accepted to the Institute of Electrical and Electronics Engineers' International Conference on Robotics and Automation (ICRA), which will be held this summer. The paper was co-authored by MIT postdoc Robert MacCurdy and Ph.D. candidate Robert Katzschmann, along with Harvard undergrad Youbin Kim.

"Our approach, which we call 'printable hydraulics,' is a step towards the rapid fabrication of functional machines," CSAIL Director Daniela Rus, who oversaw the project, said in the release. "All you have to do is stick in a battery and motor, and you have a robot that can practically walk right out of the printer."

To model this single-step process, the research team printed a small six-legged robot that is able to crawl with the aid of 12 hydraulic pumps that are embedded in its body.


How does the printer work? An inkjet printer deposits drops of material that are incredibly small -- less than half the width of a single human hair. The object is printed layer by layer, bottom to top. High-intensity UV light solidifies the materials -- with the exception of liquids -- used to create the object. Within each layer is a photopolymer, which would solidify, and a non-curing material or a liquid.

"Inkjet printing lets us have eight different print-heads deposit different materials adjacent to one another, all at the same time," MacCurdy explained. "It gives us very fine control of material placement, which is what allows us to print complex, pre-filled fluidic channels."

"As far as I'm concerned," he added, "inkjet-printing is currently the best way to print multiple materials."

The robot that was ultimately produced weighs in at 1.5 pounds and is less than 6 inches long. In order to make it mobile, a single DC motor is included that spins a crankshaft that is used to pump fluid through the machine's legs to power its movement.

"If you have a crawling robot that you want to have step over something larger, you can tweak the design in a matter of minutes," MacCurdy suggested. "In the future, the system will hardly need any human input at all -- you can just press a few buttons, and it will automatically make the changes."

Eventually, MacCurdy said this kind of robot could be used in disaster relief situations. It could be employed at a nuclear site or used to search the scene of an earthquake.

"Printable robots like these can be quickly, cheaply fabricated, with fewer electronic components than traditional robots," he added.

This research was funded partly by a grant from the National Science Foundation.

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