Robotic cubes metamorphose in space | MIT News

If you’re faced with the choice of sending a swarm of separate, full-sized robots into space, or a large crew of smaller robotic pods, you might want to call on the latter. Modular robots, like those depicted in movies like “Big Hero 6,” hold a special kind of promise for their self-assembly and reconfiguration abilities. But for all the ambitious desire for rapid and reliable deployment in areas spanning space exploration, search and rescue, and shape-shifting, the modular robots built to date are still a bit clunky. They are typically built from a menagerie of large, expensive engines to facilitate movement, necessitating a much-needed focus on more scalable architectures, both in quantity and size.

Scientists at MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) have used electromagnetism — electromagnetic fields generated by the movement of electric current — to avoid the usual stuffing of large and expensive actuators into individual blocks. Instead, they built small, inexpensive and easy-to-make electromagnets into the edges of the cubes that repel and attract each other, allowing the robots to spin and move around each other and quickly change shape. .

The “ElectroVoxels” have a side length of about 60 millimeters and the magnets are made of a ferrite core (they look like little black tubes) wrapped in copper wire, for a total cost of just 60 cents. Inside each cube are tiny circuit boards and electronic components that send current through the correct electromagnet in the correct direction.

Unlike traditional hinges that require mechanical fasteners between two elements, ElectroVoxels are completely wireless, making it much easier to maintain and manufacture a large-scale system.

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ElectroVoxels are robotic cubes that can reconfigure themselves using electromagnets. Cubes do not need motors or thrusters to move and can operate in microgravity.

To better visualize what a group of blocks would look like as they interacted, the scientists used planning software that visualizes the reconfigurations and calculates the underlying electromagnetic assignments. A user can manipulate up to a thousand cubes with a few clicks or use predefined scripts that encode several consecutive rotations. The system really puts the user in control of the fate of the blocks, within reason – you can change the speed, highlight magnets, and display movements needed to avoid collisions. You can have the blocks take different shapes (like a chair or a sofa, because who needs both?)

Small, inexpensive blocks are especially conducive to microgravity environments, where any structure you want to launch into orbit must fit inside the rocket used to launch it. After initial tests on an air table, ElextroVoxels found true weightlessness during microgravity flight, with the general impetus of better space exploration tools like thrusterless reconfiguration or modifying the inertial properties of ‘spaceship.

By taking advantage of propellantless actuation, for example, there is no need to launch additional fuel for reconfiguration, addressing many of the challenges associated with launch mass and volume. So the hope is that this method of reconfigurability can help myriad future space efforts: augmentation and replacement of space structures over multiple launches, temporary structures to aid in spacecraft inspection and astronaut assistance, and (future iterations) cubes acting as self-sorting storage containers.

“ElectroVoxels shows how to design a fully reconfigurable system and exposes our scientific community to the challenges that must be overcome to have a fully functional modular robotic system in orbit,” says Dario Izzo, Advanced Concepts Team Leader at the European Space Agency. “This research demonstrates how simple electromagnetically driven rotating cubes are to build, operate and maintain, enabling a flexible, modular and reconfigurable system that can serve as inspiration for designing intelligent components of future exploration missions. ”

To make the blocks move, they must follow a sequence, like small homogeneous Tetris pieces. In this case, there are three stages in the polarization sequence: throwing, traveling and catching, with each stage having a traveling cube (to move), an origin (where the traveling cube launches) and a destination (which catches the traveling cube). cube). Software users can specify which cube to rotate in which direction, and the algorithm will automatically calculate the sequence and address of electromagnetic assignments needed for this to happen (repel, attract, or deactivate).

For future work, moving from space to Earth is the natural next step for ElectroVoxels, which would require more detailed modeling and optimization of these electromagnets to perform reconfiguration against gravity here.

“When building a large, complex structure, you don’t want to be limited by the availability and expertise of the people assembling it, the size of your transport vehicle, or the adverse environmental conditions of the assembly site. While these axioms are true on Earth, they get much worse for building things in space,” says MIT CSAIL PhD student Martin Nisser, lead author of a paper on ElectroVoxels. “If you could have structures that fit together from simple, seamless modules, you could eliminate many of these problems. So while the potential benefits in space are particularly great, the paradox is that the favorable dynamics provided by microgravity means that some of these problems are also easier to solve – in space even small forces can do move big things. By applying this technology to solve real, short-term problems in space, we can hopefully incubate the technology for future use on Earth as well.

Nisser wrote the article alongside Leon Cheng and Yashaswini Makaram of MIT CSAIL; Ryo Suzuki, assistant professor of computer science at the University of Calgary; and Professor Stefanie Mueller of MIT. They will present their work at the 2022 International Conference on Robotics and Automation. The work was supported, in part, by the MIT Space Exploration Initiative.

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