Industrial Electronics

MIT 3-D Prints Robots with Shock-Absorbing Skins

03 October 2016

A team of researchers from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) has just 3-D printed a new kind of customized robot, paving the way for safer and more durable robots.

Robots are fragile – they lack the padding needed for them to defend themselves. But what the CSAIL team did was develop a new method for 3-D printing soft materials that will make them not only safer, but also more resilient, and even grant them more precise movements.

The new technology could potentially be used to improve the durability of drones, phones, shoes, and helmets.

It all started with the team’s “Programmable Viscoelastic Material” (PVM) technique that allows users to program every part of a 3-D-printed object to the exact levels of stiffness and elasticity they desire. This can be adjusted depending on the applications.

As an example, the researchers used a 3-D printed cubed robot that was able to move by bouncing, and supplied it with shock-absorbing “skins” that reduced the amount of energy it transferred to the ground 250%.

The cube robot includes a rigid body, two motors, a microcontroller, battery and IMU sensors. Four layers of looped metal strip serve as the springs that propel the cube. (Image Credit: Jason Dorfman, MIT CSAIL)The cube robot includes a rigid body, two motors, a microcontroller, battery and IMU sensors. Four layers of looped metal strip serve as the springs that propel the cube. (Image Credit: Jason Dorfman, MIT CSAIL)

“That reduction makes all the difference for preventing a rotor from breaking off of a drone or a sensor from cracking when it hits the floor,” said Daniela Rus, CSAIL Director, who oversaw the project and co-wrote a related paper. “These materials allow us to 3-D print robots with visco-elastic properties that can be inputted by the user at print-time as part of the fabrication process.”

The skins the team created allow the robot to land about four times more precisely, which suggests that similar shock absorbers could be used to extend the lifespan of delivery drones that we see popping up all over the place these days.

3-D Printing the Materials

The most commonly employed damper materials are “viscoelastics” such as rubber and plastic. These materials possess both solid and liquid qualities. Viscoelastics are inexpensive, compact and easily accessible, but are typically only commercially available in specific sizes and at specific damping levels because they take a long time to produce.

This is when the team decided on 3-D printing as a solution. By being able to deposit materials with different mechanical properties into a design via 3-D printing, users can “program” material to their exact needs for each part of an object.

“It’s hard to customize soft objects using existing fabrication methods, since you need to do injection moulding or some other industrial process,” said Jeffrey Lipton, lead author on the paper. “3-D printing opens up more possibilities and lets us ask the question, ‘can we make things we couldn’t make before?”

The team used a standard 3-D printer, a solid, a liquid and a flexible rubber-like material called TangoBlack+ and was able to print both the cube and its skins.

“By combining multiple materials to achieve properties that are outside the range of the base material, this work pushes the envelope of what’s possible to print,” said Hod Lipson, a professor of engineering at Columbia University and co-author of “Fabricated: The New World of 3-D Printing.” “On top of that, being able to do this in a single print-job raises the bar for additive manufacturing.”

According to Rus, PVMs could have a variety of potential protective uses, including shock-absorbing running shoes and headgear. For example, curbing the motion brought about by robots’ motors, PVMs would be able to protect sensitive parts like cameras and sensors, as well as make the robots easier to control.

The new paper will be presented at the IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS) in Korea.

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