3D-Printed Robotic Hand Successfully Plays Super Mario Bros
A team of researchers from the University of Maryland has 3D printed a soft robotic hand that is agile enough to play Nintendo's Super Mario Bros. - and win! Image: University of Maryland
The first level of the original Super Mario Bros game is a piece of cake for most people, but has always represented a major hurdle for robot-kind – until now. According to a new study in the journal Science Advances, researchers have created a 3D-printed robotic hand that has sufficient agility and finesse to operate a video game controller, and can complete the first level of the Nintendo Entertainment System (NES) classic in under 90 seconds.
The new system represents a major step forward within the field of “soft robotics”, which involves the use of highly flexible components that are manipulated by flowing water or air rather than electrical signals. While this concept holds great promise for the development of next-generation prosthetics, the technology required to control the flow of these fluids has posed a major hindrance.
“Previously, each finger of a soft robotic hand would typically need its own control line, which can limit portability and usefulness,” said study author Joshua Hubbard in a statement.
“But by 3D printing the soft robotic hand with our integrated ‘fluidic transistors’, it can play Nintendo based on just one pressure input.” In other words, the movement of all fingers and joints on the hand can be controlled by one flowing fluid. Furthermore, the entire device can be built in a single print run.
“Within the span of one day and with minor labor, researchers can now go from pressing ‘start’ on a 3D printer to having complete soft robots – including all of the soft actuators, fluidic circuit elements, and body features – ready to use,” said study co-author Kristen Edwards.
In their paper, the researchers explain how the fluids that control the device mimic the nature of electrical signals and were first tested on a 3D-printed robotic turtle. For example, a constant flow of fluid, which is analogous with direct current (DC) electrical signals, was used to control the continual oscillation of the turtle’s limbs. A fluctuating flow, meanwhile, mirrors the nature of alternating current (AC) signals and caused the turtle to move its flippers periodically.
The robotic hand was designed to respond to the changing magnitude of flow, which could toggle between low, medium and high pressures, thus mirroring a variable current. In this case, a low pressure input caused the first finger to press the forward button on the controller’s directional pad, prompting Mario to walk. As pressure increased, the movement of different fingers became activated so that Mario could be made to jump and perform other maneuvers.
By preprogramming the control input so that the pressure changed at the appropriate times, the study authors were able to use their hand to guide the mushroom-loving plumber all the way to the finish line.
“We are freely sharing all of our design files so that anyone can readily download, modify on demand, and 3D print… all of the soft robots and fluidic circuit elements from our work,” said project leader Ryan Sochol.
“It is our hope that this open-source 3D printing strategy will broaden accessibility, dissemination, reproducibility, and adoption of soft robots with integrated fluidic circuits and, in turn, accelerate advancement in the field.”
Soft Robot Hand Is First to Be Fully 3-D-Printed in a Single Step
Then it played Super Mario Bros.
Soft robotic hand can press buttons quickly enough to beat the first level of Super Mario Bros. Credit: Joshua Hubbard and Kristen Edwards
A soft robotic hand has finally achieved a historic accomplishment: beating the first level of Super Mario Bros. Although quickly pressing and releasing the buttons and directional pad on a Nintendo Entertainment System controller is a fun test of this three-fingered machine’s performance, the real breakthrough is not what it does—but how it was created.
The Mario-playing hand, as well as two turtlelike “soft robots” described in the same recent Science Advances paper, were each 3-D-printed in a single process that only took three to eight hours. “Every one of those robots in this paper was 100 percent no-assembly-required-printed,” says co-author Ryan Sochol, an assistant professor of mechanical engineering at the University of Maryland.
One-step production would make it easier for researchers to develop increasingly complex soft robots. These bots’ squishy makeup lets them interact with delicate materials—such as tissues in a human body—without the kind of damage more rigid machines might cause. This makes them good candidates for tasks such as performing surgery or search and rescue and even sorting fruit or other easily damaged items. But so far most such bots still include at least some rigid components. It was not until 2016 that researchers created one entirely from flexible materials. To make that octopuslike soft robot work, its creators had to ditch rigid electronic circuits for a microfluidic one. In such circuits, water or air moves through microchannels; its flow is modified by fluid-based analogues to electronic components such as transistors and diodes.
In the new study, the researchers stepped up the development of this technology. “They introduced much more complicated microfluidic circuits,” says Harvard University engineering professor Jennifer Lewis, who co-authored the 2016 paper but was not involved in the University of Maryland’s project. In the Mario-playing hand, for example, the circuit allowed a single source of fluid to send different signals, telling each finger to move independently by simply varying the input pressure.
Printing It Up
But in making soft robots more sophisticated, fluidic circuits also render the machines harder to manufacture and assemble. That is why Sochol is so excited about printing them in one step. “Never once has it been done all in a single run,” he says, “to have an entire soft robot with all of the integrated fluidic circuitry and the body features and the soft actuators [moving parts] all printed.”
He and his colleagues used a PolyJet 3-D printer, a type that sets down a liquid layer, exposes it to a light that solidifies it and then adds the next layer. The model they employed, manufactured by a company called Stratasys, could produce three types of material: a soft rubberlike substance, a more rigid plasticlike one and a water-soluble “sacrificial material” that acts as scaffolding during printing but must be removed from the final product afterward.
Such high-tech printers can retail for tens of thousands of dollars—but Sochol’s team did not need to buy one. “We use a service on campus to do this,” he says. “So we sent our files to them, they printed it, and then we picked it up.” Sochol estimates that anyone else wanting to print one of these designs—which his team shared as open-access software on the development site GitHub—could use a similar 3-D-printing service for about $100 or less.
Sochol contends this process is faster, cheaper and easier than fabricating a microfluidic circuit in a clean room, creating a robot separately and then combining them later. Lewis does not entirely agree. “There’s an elegance to it. I’m not sure it’s faster, cheaper, necessarily,” she says. “But there is cumbersome nature to having to create the circuit by one method and then insert it, like we did, into a molded and 3-D-printed robot. And I would say that the method that [Sochol and his colleagues] chose ... has many advantages in terms of being able to print multiple materials of different stiffness.” Lewis also points out that the new soft bot is not ready to go immediately after printing. “One cumbersome part of their method is that you have to remove all the sacrificial material,” she says. “And when it’s on the outside of the body, just as support, that’s fine. But it’s also present in all of those internal channels.”
It’s-a Me, Mario!
After cleaning up their printed robots, Sochol’s team had to design a performance test. Earlier studies have programmed robotic fingers to play a tune on a piano, for example, but Sochol’s team thought that task was too easy. “With that, we could set the tempo arbitrarily, he says. “If the robot misses a note or something like that, there’s no meaningful penalties.” Video games seemed a little more uncompromising. “If you make a mistake, if we don’t press the button at the right time or we don’t [release] the button at the right time, you can run into an enemy, you can fall down a pit, and it’s an immediate game over,” Sochol says.
The researchers placed their three-fingered robotic hand on a Nintendo controller, with each finger laid on a different button or the directional pad. By feeding fluid through a control line at different pressures, they could make each finger respond. “For a low pressure, the circuit is able to respond to that and press only the button that causes Mario to move forward,” Sochol explains. “And then for a medium pressure, a second finger begins to press a button, and now Mario can run. And then if it’s a high pressure, then all three fingers will be pressing their respective buttons, and Mario will jump.”
The team wrote a computer program that would change the pressure automatically, causing the fingers to move in a set pattern. Because people have been playing Super Mario Bros. for decades, the team knew exactly what sequence of buttons the hand would need to press to win the game’s first level. It just had to run through that preprogrammed list with the correct timing—which is harder than it sounds. The challenging part, Sochol says, was “getting it to not just press a button but then stop pressing it and then repress it, because there’s a lot of times where Mario has to jump and then jump again very quickly as he’s running.”
“The Mario part is kind of cute and certainly will be attention-grabbing,” Lewis says. “But I think what’s really powerful about this paper is the multimaterial 3-D printing, the ability to integrate all of this complex fluidic circuitry in one fab step. There’s really a lot to like about what [the researchers have] done.”
Winning the video game showed that the fully printed robotic hand could respond swiftly and accurately to a changing input. Any well-known video game could have made this point, but Mario holds a special place in many players’ hearts. “We felt like this was the baseline game,” Sochol says. “When I was a four- or five-year-old, and we got a Nintendo system, that was the very first thing that I played ever.”
World's first 3D printed steel bridge weighing 4.9 tons opens to public in Amsterdam
You may have heard of 3D movies and paintings, but would you dare walk on a 3D steel printed bridge? Amsterdam installed the world's first, built to withstand heavy pedestrian traffic.
The bridge, which is open to pedestrians and cyclists, was created by the Imperial College London and took more than four years to build, according to a news release. The bridge was publicly revealed by Queen Máxima of the Netherlands.
The almost-40-foot structure weighs 4.9 tons and will be carefully monitored using installed sensors. The creators will watch the bridges structural state and public interaction, according to the release. The data collected from the sensors will be transferred to a digital version of the bridge, which will mimic the physical one. This way, creators can test the performance of the physical bridge against the digital one.
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The bridge was installed over the Oudezijds Achterburgwal canal in Amsterdam’s Red Light District and was unveiled July 15.
“A 3D-printed metal structure large and strong enough to handle pedestrian traffic has never been constructed before. We have tested and simulated the structure and its components throughout the printing process and upon its completion, and it’s fantastic to see it finally open to the public," Imperial co-contributor professor Leroy Gardner of the Department of Civil and Environmental Engineering said in the release.
The bridge was built using four industrial robots and took about six months of printing. Managed by Dutch company MX3D, robots used welding torches to cement each printed layer of the bridge, according to the release.
To take the bridge from an idea to a walkway, the Imperial College's Steel Structures Research Group conducted destructive force-testing on printed elements, real-world testing on the walkway and research on the development of an advanced sensor network, according to the release.
"3D printing presents vast opportunities for the construction industry, providing much greater freedom in terms of material properties and shapes," Gardner said. "This freedom also brings a number of challenges and will require structural engineers to think in new ways."