From butterflies sprouting wings to hermit crabs changing their shells, many animals must adapt their external features to survive. Although humans don’t undergo this kind of metamorphosis, we often strive to create functional objects that are similarly adaptive – including our robots.
However, despite what you may have seen in the “Transformers” movies, today’s robots are still quite inflexible. Each of their parts usually has a fixed structure and one specific purpose, which makes it hard for them to perform a wide range of activities.
Researchers at MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) want to change that with a novel shape-shifting robot that resembles a superhero: it can transform with different “suits” that allow it to perform different tasks.
The cube-shaped robot, called “Primer”, can be controlled using magnets so that it can walk, roll, sail and glide. It performs these activities by wearing a variety of exoskeletons that start as sheets of plastic that fold into specific shapes when heated. After Primer has done its job, it can shed its “skin” by immersing itself in water, which dissolves the exoskeleton.
“If we want robots to help us perform various activities, having a different robot for each task is not very effective,” says Daniela Rus, director of CSAIL and principal investigator of the project. “With a metamorphosis-inspired approach, we can expand the capabilities of a single robot by giving it different ‘accessories’ to use in different situations.”
Different forms of foundation have a number of advantages. For example, “Wheel-bot” has wheels that allow it to move twice as brisk as “Walk-bot”. The “boat-bot” can float on water and carry almost twice its weight. The “Glider-bot” can glide longer distances, which can be useful for deploying robots or changing the environment.
Primer can even wear multiple outfits at once, like a Russian nesting doll. It can add one exoskeleton to become a “Walk-Bot” and then connect to another, larger exoskeleton that allows it to carry objects and move two body lengths per second. To deploy the second exoskeleton, the “Walk-bot” steps onto a sheet, which then covers the robot with four self-folding arms.
“Let’s imagine future applications of space exploration in which we can send a single robot with a stack of exoskeletons to Mars,” says postdoctoral fellow Shuguang Li, one of the study’s co-authors. “The robot could then perform different tasks while wearing different ‘outfits.'”
The project was led by Rus and Shuhei Miyashita, a former postdoc at CSAIL and now director of the Microrobotics Group at the University of York. Their co-authors are Li and graduate student Steven Guitron. An article about the work will be published in the magazine on September 27.
Robot metamorphosis
Primer builds on several previous designs by Rusa’s team, including magnetic blocks that can be folded into different shapes and centimeter-long microrobots that can be precisely customized from sheets of plastic.
Although robots that change their form or function at larger sizes have been developed, it has generally been hard to build such structures on a much smaller scale.
“This work is an improvement over the authors’ previous work in that they have now demonstrated a scheme that can create five different functionalities,” says Eric Diller, an expert in microrobotics and assistant professor of mechanical engineering at the University of Toronto, who was not involved in the paper. “Previous work focused on at most two functionalities, such as “open” and “closed” shapes.
The team outlines a number of potential applications for robots that can perform multiple tasks with a quick costume change. For example, say some equipment needs to be carried across a stream. A single robot with multiple exoskeletons could potentially swim across the stream and then carry the items on the other side.
“Our approach shows that origami-inspired manufacturing allows us to create robotic components that are versatile, accessible, and reusable,” says Rus, the Andrew and Erna Viterbi Professor of Electrical Engineering and Computer Science at MIT.
Designed in a matter of hours, the exoskeletons take shape after just a few seconds of heating, suggesting a novel approach to rapidly manufacturing robots.
“I can imagine such devices being used in ‘microfactories,’ where prefabricated parts and tools enable a single microrobot to perform multiple complex tasks on demand,” Diller says.
In the next step, the team plans to explore opportunities to give the robots an even wider range of capabilities, from moving through water and digging in sand to camouflaging color. Guitron envisions a future robotics community that shares open-source part designs in much the same way that 3D printing enthusiasts exchange ideas on sites like Thingiverse.
“I imagine that one day I will be able to customize robots to my own needs with different arms and attachments,” says Rus. “Why update the entire robot when you can only update one part of it?”
This project was supported in part by the National Science Foundation.