New 3D printing technique can make autonomous robots in one step

Building a robot is difficult. Building one that can sense its surroundings and learn to move on its own is even harder.

But UCLA engineers took on an even bigger challenge. Not only did they create autonomous robots, but they 3D printed them in one step.

Each robot is about the size of a finger. Their body resembles a bamboo mat bent into an N shape, and they glide at speeds of up to 25 feet per minute.

What made this feat possible was the invention of a new type of all-in-one material that could bend, twist, flex and stretch.

“The traditional robots you see today rely on several different components,” said Rayne Zheng, mechanical engineer and project leader. The robot body, its moving parts and its electronics must be built separately and then assembled. “With 3D printed materials that can be robotized, we don’t need any of that.”

The breakthrough, described last month in the journal Science, paves the way for inventions ranging from nimble rescue robots that can navigate tight spaces to responsive prosthetics with fewer parts that can break.

UCLA researchers have developed materials that allow tiny robots to become autonomous after receiving basic commands.

“A lot of times 3D printing is sort of used as a novelty to generate hype…but that’s not the case here,” said Ryan Sochol, a robotics engineer at the University of Maryland who n did not participate in the study. .

Robert MacCurdy, who designs automated robots at the University of Colorado at Boulder, called UCLA’s work “a real breakthrough in 3D printing technology.” He said printing a mobile, shape-shifting material with embedded electronics and remote sensing capabilities had never been done before, and it foreshadows “robot production in the future.”

Zheng and his colleagues embarked on the project three years ago to see if they could use 3D printing to build a material that could sense its surroundings – to measure the surrounding temperature, for example, and to notice if he was hit or crushed. .

Once they reached that goal, they added another one. “We started thinking, in addition to feeling, why not make it move?” Zheng said.

And they always wanted to do it all in one step.

Ordinary 3D printers work like a machine that adds icing to a cake. They accumulate thin layers of plastic, metal, glass or other materials to produce an endless list of products such as jewelry, tools, prosthetics and even pizza. But they can only print one component at a time.

To print an entire robot in one go, Zheng and his colleagues needed a versatile material. They therefore created one in silicon carbide, which supports the structure of the robots; copper and gold electrodes, which carry the current; and piezoelectric ceramics, which change shape in response to an electric field.

Each part contributes an entirely new “metamaterial” that can bend and flex, stretch and compress, twist and turn, said Huachen Cui, a postdoctoral researcher in Zheng’s lab who led its development. And the metamaterial can be 3D printed in one go.

The new material required a custom 3D printer. So the team built one that takes up the space of an office. The way it works is similar to instantly freezing a design in a glass of water and draining the rest, leaving behind an intricate ice sculpture. But instead of water, the printer alternates between vats of the three ingredients, then uses ultraviolet light to solidify each layer of the metamaterial network as the robot takes shape.

A close up of the 3D printed lattice that forms the base of the robots.

A close up of the 3D printed lattice that forms the base of the robots. Complex elements are designed to bend, flex, twist, rotate, expand or contract at high speed.

(Rayne Research Group/UCLA)

The result is basically like a muscle. “Everything is integrated, from structural components to sensing components, to movement and electronic control,” Zheng said.

In other words, according to MacCurdy, it is a truly functional object: “When it comes out of the 3D printer, it requires no further assembly.

Cui put a robot to the test by placing it on a table between a pair of pipes. A set of wires attached the robot to a power source. When the power was turned on, the robot came to life with an unusual bright green flash accompanied by billowing smoke. But soon it was moving with the soft hum of an electric razor.

The three parts of his N-shaped body form a muscle that flexes faster than the eye can discern, propelling him forward with ease. It can even jump over tiny hedges about 1 millimeter high.

The design was inspired by nature.

“I wanted to make it nimble and very fast – the first thing I thought of was a leopard,” said Cui, who was the study’s lead author. “Just hit the ground and move forward. That’s it.”

Robots rely on ultrasound to sense their environment, like bats. But instead of using echolocation, the machines use a 3D-printed remote sensor that bounces radar pulses in different directions. The way they bounce alerts the robot to obstacles in its path so it can adapt accordingly.

The machines, which are small enough to fit on a penny, can carry more than 13 times their own weight. When Cui dropped a bolt into a basket attached to the top of the robot, it shook and started moving faster. The impact, intended to mimic falling debris, was his cue to make a quick escape, he said.

Zheng said it wouldn’t be difficult to make the robots bigger – all they would need is a bigger 3D printer. The real challenge is to make the robots smaller and able to operate in water.

This is something that excites Sochol.

“I think biomedical applications, particularly drug delivery, is one application where it could really have a legitimate use,” he said. He imagined a scenario in which a small robot transports a dose of medicine to a particular place in a blood vessel. Once it’s in place, doctors could “hit it with an electric field” to get it to release its payload.

Zheng’s lab is already equipped with a small tank on the ground to test a future generation of aquatic robots. If a leopard inspired the original version, the new ones will be designed to mimic the swimming and crawling abilities of shrimp.

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