Engineers at Harvard University have developed a robot that assembles itself into a complex shape in four minutes and then crawls away without any human intervention. It was inspired by origami and a classic children’s toy.
“Getting a robot to assemble itself autonomously and actually perform a function has been a milestone we’ve been chasing for many years,” says Robert Wood, a professor at the School of Engineering and Applied Sciences (SEAS) and a core faculty member at the Wyss Institute for Biologically Inspired Engineering.
“We investigated cheap, fast and easy ways of being able to build machines and robots based on folding,” explains Wood. “Robots in general are complex mechanisms. They have articulation; some number of degrees of freedom; they must interact with the world; and they are traditionally difficult to make and control.”
Wood and his colleagues developed a four-legged robot whose body and mechanisms are assembled through the folding process. Their design is based on the principles of origami, an ancient Japanese art in which a single sheet of paper can be folded into complex structures.
The engineers started with a flat sheet of 8½-by-11-inch paper and then added two motors, two batteries and a microcontroller. The sheet is a composite of paper and prestretched polystyrene similar to Shrinky Dinks—a toy that shrinks by 50 percent when heated above 212 F—with a single flexible circuit board in the middle. It also included hinges that are programmed to fold at specific angles.
Each hinge contains embedded circuits that produce heat on command from the microcontroller. The heat triggers the composite to self-fold in a series of steps.
When the hinges cool after about four minutes, the polystyrene hardens—making the robot stiff—and the microcontroller then signals the robot to crawl away at a speed of more than two ips. The robot operates on a timer, waiting about 10 seconds after the batteries are installed to begin folding.
“The folding is induced by the materials in the composite, and the sequence in which you activate the materials is controlled by an on-board microcontroller,” says Wood. “In this case, the self-folding is thermally induced.”
The method is complementary to 3D printing, which also holds great promise for quickly and inexpensively manufacturing robotic devices, but struggles to integrate electrical components.
The robots are the culmination of a series of advances made by Wood and his colleagues over the last few years, including a printed robotic inchworm—which still required human involvement while folding itself—and a self-folding lamp that had to be turned on by a person after it self-assembled.
According to Wood, the foldable robot demonstrates the potential to quickly and cheaply build sophisticated machines that interact with the environment, and to automate much of the design and assembly process.
“In addition to expanding the scope of ways one can manufacture robots in general, the advance harbors potential for rather exotic applications,” says Wood. “Imagine dozens of robotic satellites sandwiched together so that they could be sent up to space and then assemble themselves remotely once they get there. Larger and perhaps more functional load-bearing structures could also be made this way—things like shelters or Ikea-style furniture.”
Wood envisions a network of local facilities that people could access “when they have a need for robotic assistance, from everyday house and porch sweeping to detecting gas leaks in the neighborhood. You would be able to come in, describe what you need in fairly basic terms, and come back an hour later to get your robotic helper,” he points out.
“This changes the way we think about manufacturing in that the machine fabricates itself,” claims Don Ingber, a professor of bioengineering at SEAS and a professor of vascular biology at Harvard Medical School. “The days of big, rigid robots that sit in place and carry out the same repetitive task day in and out are fading fast.”
To learn more about the self-assembling technology, click here to watch a video.