Modular Robotic Cubes With No External Moving Parts Can Jump & Self-Assemble

M-Blocks are robotic cubes, developed by MIT researchers, that have no external moving parts. Even so, they're able to climb over and around one another, jump, roll, and move while suspended upside down from metallic surfaces. Inside each M-Block is a flywheel that can reach speeds of 20,000 revolutions per minute - when the flywheel is braked, it imparts its angular momentum to the cube. On each edge of an M-Block, and on every face, are permanent magnets that allow any two cubes to attach to each other. The simplicity of the cubes' design makes miniaturization promising. In ongoing work, the MIT researchers are building an army of 100 cubes, each of which can move in any direction, and designing algorithms to guide them. "We want hundreds of cubes, scattered randomly across the floor, to be able to identify each other, coalesce, and autonomously transform into a chair, or a ladder, or a desk, on demand," says lead researcher John Romanishin.

Transcript

00:00:09 Our objective is to design self- assembling and self-reconfiguring robot systems. These are modular robots with the ability of changing their geometry according to a task. And this is exciting because a robot designed for a single task has a fixed architecture and that robot will perform the single task well but

00:00:31 it will perform poorly on a different task in a different environment. If we do not know ahead of time what the robot will have to do and when it will have to to it, it is better to consider making modular robots that can attain whatever shape that is needed for the manip- ulation, navigation or sensing

00:00:49 needs of the task. Up until now most other modular robotic systems use servos and motors in order to have arms that and attachments that move modules to different places. However we wanted a simpler approach that uses fewer actuators, fewer moving parts and was easier to implement on a lot of different

00:01:07 robots. So the approach we chose to use is angular momentum. And essentially what that means is there is a spinning mass that spins inside the robot. If we want that robot to move it stops that spinning mass which takes that motion from the mass and applies it to the robot. And the part of this that is unique is

00:01:22 that the spinning mass is completely inside the robot and so the robot doesn't have to be in a certain position in order for the force to be acted upon the robot so this allows for a lot more types of motion with only one actuator. So there were a couple challenges when we came to design the

00:01:38 m-blocks, one, was fitting everything inside. So we have a relative small volume and we needed to fit a brushless motor controller, a flywheel, a breaking mechanism, electronics a radio and a battery. Additionally we faced the challenge of trying to simplify and try and make the design as

00:01:54 robust as possible. So we didn't want any external moving parts. We didn't want latches, we didn't want the cubes to change their shape. We just wanted simple blocks that were able to move on their own. The magnet system in the cubes is one of its key features. We have face magnets. There's eight face

00:02:10 magnets that provide some course alignment and then there are these edge magnets which are free to rotate. And the key is that when a cube starts rotating the edge magnets actually get close to one another. So if we start from this configuration and we break the face magnets free and start rotating the edge

00:02:28 magnets actually get a little bit closer due the fact that the edge is slightly cut back and as a result you form a very strong bond between cubes which allows them to stay attached as one is rotating into a new position. It continues rotating, the face magnets provide alignment and it snaps into place.

00:02:46 One other benefit of having an internal actuator is that the cubes are able to jump and this is a capability that very few robots have. Especially very few modular robots because in order to jump there's a requirement for a very high amount of energy in a very short amount of time and most robots

00:03:02 are optimized for control, stability and precise motion. In our robot we found it kind of as an accident that they are able to jump, we weren't intending to do that but it ends up that we need enough momentum inside each cube in order to move on a lattice structure, which is what we intended, that

00:03:17 we can also, when we apply as much energy as possible, it can jump through the air which is pretty exciting because it also allows robots to jump on top of each other and go places that they couldn't go if they were only moving directly on the structure. Currently we're sending commands to the modules

00:03:35 with a radio. So we type commands on our computer, those are transferred over a wireless link like your wifi system in your house, and then the cube responds to that. In the future we envision putting the algorithms on the modules themselves so they can completely, autonomously in a distributive fashion decide

00:03:53 how, when and where to move. So we want to be able to take a large group of cubes and tell them form this shape, and give those instructions at a very high level and then have the cubes decide, on their own, how to go about accomplishing that task.