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A team led by University of Maryland mechanical engineering professor Ryan Sochol created a flexible robotic hand agile enough to manipulate a game controller.
A team of engineers from the University of Maryland built a flexible three-finger robotic hand agile enough to be able to manipulate the buttons and directional pad of a Nintendo controller, even managing to beat the first level of Super Mario Bros. as proof of concept, according to a recent article published in the journal Science Advances. The same team also built two robotic softshell turtles (the terrapin turtle is the official mascot of UMD) using the same multi-material 3D printing process that produced the robotic hand.
We traditionally think of robots as being made from hard and rigid materials, but the sub-field of soft robotics takes a different approach. He seeks to build robotic devices from more flexible materials that mimic the properties of those found in living animals. There are huge benefits to be gained by crafting a robot’s entire body from soft materials, such as being flexible enough to squeeze into tight spaces to search for survivors after a disaster. Soft robots also have great potential as prostheses or biomedical devices. Even rigid robots rely on soft components, such as foot pads that act as shock absorbers or flexible springs to store and release energy.
Harvard researchers built a flexible octopus-inspired robot in 2016, constructed entirely from flexible materials. But soft robots are harder to control precisely because they are so flexible. In the case of the “octobot”, the researchers replaced the rigid electronic circuits with microfluidic circuits. Such circuits consist in regulating the flow of water (hydraulic) or air (pneumatic), rather than electricity, through the microchannels of the circuit, allowing the robot to bend and move.
Although this solution is ingenious, it brings its share of challenges. These include the high cost (cleanroom facilities are required) and the time required to fabricate these microfluidic systems and then integrate them into the system as a whole. “Recently, several groups have attempted to exploit fluidic circuits to improve the autonomy of soft robots,” said co-author Ruben Acevedo. “But the methods of building and integrating these fluidic circuits with the robots can take days to weeks, with a high degree of manual labor and technical skill.”
As an undergraduate student, Acevedo worked in the lab of University of Maryland mechanical engineer Ryan D. Sochol, who wanted to go beyond manually connecting fluidic circuit components to devices. soft robots to integrate these functions directly into soft robotic systems. His team found the answer in PolyJet 3D printing, in which several different layers of materials are stacked on top of each other. The printer deposits a liquid layer, lets it solidify, then deposits the next layer, and so on.
YouTube / UMD A. James Clark School of Engineering
“The incorporation of materials that differ in stiffness serves to improve performance by allowing material properties of specific characteristics to be tailored to complement desired functionality”, Sochol et al. written in their journal. Components such as diaphragms and o-rings must be able to deform during operation, which is why a soft rubber-like material was used to make them, while a stiffer plastic-like material was chosen. to fabricate components that must be stable (fluidic channels, access ports and structural envelopes, for example). Finally, the team used a water-soluble material to serve as a scaffold during the printing process, which was then removed from the outer and inner voids and channels, first by dissolving the material with water, then manually removing any remaining scaffolding material.
Microfluidically controlled flexible robots generally require separate control inputs for each independently operating flexible actuator. By integrating the fluidic circuit, the UMD team was able to actuate the hand by varying the pressure force between low, medium and high. In other words, a single fluid source could send different signals just by changing the pressure, so that each finger could move independently. Best of all, the one-step 3D printing process for the hand and the two turtle robots, including flexible actuators (moving parts), fluidic circuits and the robot body, took hours, not days or days. weeks.
The team tested the performance of the robotic hand by playing it Super Mario Bros. To make Mario work, the team used light pressure, so only the first finger pressed the controller. The researchers used medium pressure to make Mario run and high pressure to have the hand press the correct button on the controller to make Mario jump.
YouTube / UMD A. James Clark School of Engineering
As to why they chose Super Mario Bros., Sochol told Scientific American that it was the very first Nintendo game he had played as a child. But the choice wasn’t just a matter of nostalgia. The timing and specifics of the game are well established; the robot’s hand simply needed to time its responses according to the preprogrammed movements. And there are real consequences for failure: a single mistake will cost Mario his life. The hand worked so well that it managed to beat the first level of the game in under 90 seconds.
“We freely share all of our design files so that anyone can easily download, edit on demand, and 3D print, whether with their own printer or through a print service like us, all software robots and elements. of fluidic circuits of our work. “said Sochol, who estimates that printing his own software bots would cost around $ 100 using the team’s software on GitHub.” We hope this open source 3D printing strategy will expand accessibility, distribution, the reproducibility and adoption of flexible robots with integrated fluidics circuits and, in turn, will accelerate advancements in the field. “
DOI: Science Advances, 2021. 10.1126 / sciadv.abe5257 (About DOIs).
List image by University of Maryland
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