PRINTABLE HYDRAULICS, SOLID AND LIQUID ROBOTS 3D-STYLE 48 May 2016 3 D P R I N T I N G Hydraulically-powered 3D printed robot bodies with no assembly required One reason we don’t yet have robot personal assistants buzzing around doing our chores is because making them is darn hard. Assembling robots by hand is time-consuming, while automation — robots building other robots — is not yet fine-tuned enough to make robots that can do complex tasks. But if humans and robots can’t do the trick, what about 3D printers? In a new paper, researchers at MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) presenedt the first-ever technique for 3D printing robots that involves printing solid and liquid materials at the same time. The new method allows the team to automatically 3D print dynamic robots in a single step, with no assembly required, using just a commercially-available 3D printer. “Our approach, which we call ‘printable hydraulics,’ is a step towards the rapid fabrication of functional machines,” says CSAIL director Daniela Rus, who oversaw the project and co-wrote the paper. “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 demonstrate the concept, researchers 3D printed a tiny six-legged robot that can crawl via 12 hydraulic pumps embedded within its body. They also 3D printed robotic parts that can be used on existing platforms, such as a soft rubber hand for the Baxter research robot. The printing process For all of the progress in 3D printing, liquids continue to be a big hurdle says co-writer of the paper Robert MacCurdy (MIT postdoc). Printing liquids is a messy process, which means that most approaches require an additional post-printing step such as melting it away or having a human manually scrape it clean. That step makes it hard for liquid-based methods to be employed for factory-scale manufacturing. With printable hydraulics, an inkjet printer deposits individual droplets of material that are each 20 to 30 microns in diameter, or less than half the width of a human hair. The printer proceeds layer-by-layer from the bottom up. For each layer, the printer deposits different materials in different parts, and then uses high-intensity UV light to solidify all of the materials (minus, of course, the liquids). The printer uses multiple materials, This 3D 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. Among the robot’s key parts are several sets of ‘bellows’ 3D printed directly into its body. To propel the robot, the bellows uses fluid pressure that is translated into a mechanical force. (As an alternative to the bellows, the team also demonstrated they could 3D print a gear pump that can produce continuous fluid flow)
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