Self-Assembling Modular Robots Show Promise in Inspection and Rescue Operations

Simple and interacting robots, in large numbers, can possibly unlock stealthy capabilities for realizing complicated tasks. However, it has been rather challenging to get these robots to achieve a real hive-like mind of coordination.

In an attempt to overcome this challenge, a team of researchers from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) has developed an amazingly simple strategy—self-assembling robotic cubes that can roll across the ground, jump through the air, and climb over and around one another.

Six years following the first iteration of the project, the self-assembling robots can presently “communicate” with one another through a barcode-like system on every face of the block. This block enables the modules to recognize one another. The autonomous fleet, totaling 16 blocks, can currently achieve simple behaviors or tasks such as tracking light, following arrows, or forming a line.

Every modular “M-Block” is integrated with a flywheel that moves at 20,000 revolutions every minute and uses angular momentum when it is halted. Permanent magnets, located on each edge and every face, allow any two cubes to adhere to one another.

Although the cubes cannot be exploited as easily as, for example, those from the video game “Minecraft,” the researchers believe that they could provide robust applications in inspection, and ultimately disaster response. One can imagine a burning building, where a staircase has vanished.

In the coming days, one could simply throw the M-Blocks on the ground and watch them build out a transitory staircase for ascending the roof, or descending the basement to save victims.

M stands for motion, magnet, and magic. ‘Motion’, because the cubes can move by jumping. ‘Magnet’, because the cubes can connect to other cubes using magnets, and once connected they can move together and connect to assemble structures. ‘Magic’, because we don’t see any moving parts, and the cube appears to be driven by magic.

Daniela Rus, Professor, Massachusetts Institute of Technology

Rus is also the Director at CSAIL.

The mechanism is rather complex on the inside, but the exterior is just the reverse, enabling stronger connections. Apart from rescue and inspection applications, the team also believes that the blocks can be used for things like health care, manufacturing, and gaming.

The unique thing about our approach is that it’s inexpensive, robust, and potentially easier to scale to a million modules. M-Blocks can move in a general way. Other robotic systems have much more complicated movement mechanisms that require many steps, but our system is more scalable.

John Romanishin, Study Lead Author and PhD Student, Computer Science and Artificial Intelligence Laboratory

Romanishin penned the article along with Rus and John Mamish, an undergraduate student from the University of Michigan. The team will present the article on M-blocks at IEEE’s International Conference on Intelligent Robots and Systems. The conference will be held in Macau in November.

Earlier modular robot systems usually deal with movements by utilizing unit modules that have tiny robotic arms called external actuators. Systems like these need plenty of coordination for even the most basic movements, with numerous commands for a single hop or jump.

Other efforts, on the communication side, have involved the use of radio waves or infrared light. But these can rapidly become clunky—if one has plenty of robots in a compact area and they are all attempting to send signals to one another, it would open up a chaotic channel of confusion and conflict.

When radio signals are used by a system to interact, the signals can obstruct one another, specifically when there are numerous radios in a small volume.

Earlier in 2013, the researchers constructed their mechanism for M-Blocks. As such, six-faced cubes were developed that move about using something known as “inertial forces.” This implies that the blocks do not use the moving arms that help them to link the structures, but instead, they have a mass within them. The blocks “throw” this mass against the side of the module, which, in turn, makes the blocks to spin and move.

When each module is placed on any one of the six faces, it can move in four cardinal directions. This results in 24 varied movement directions. Without appendages and small arms protruding from the blocks, the modules find it relatively easier to avoid collisions and stay free of damage.

Knowing that the researchers had addressed the physical barriers, the critical challenge still remained—that is, how to make the cubes to communicate and consistently detect the configuration of adjacent modules.

Romanishin developed algorithms that were specifically made to assist the robots to accomplish easy “behaviors” or tasks. This eventually led the researchers to the concept of a barcode-like system where the robots can detect the face and identity of other blocks to which they are linked.

During one experiment, the researchers had the modules turn into a line from an arbitrary structure, and they observed whether the modules are able to establish the particular way they were linked to one another. If they fail to do so, then they would have to pick a direction and roll that way until they reached the end of the line.

Fundamentally, the blocks applied the configuration of the way they are linked to one another to guide the motion that was selected by them to move—and 90% of the M-Blocks were successful in getting into a line.

The researchers observed that it was very difficult to construct the electronics, particularly when attempting to accommodate complex hardware within a compact package. However, the researchers want precisely that to make the swarms of M-Blocks a bigger reality, that is, an increasing number of robots to make larger swarms with more robust capabilities for numerous structures.

The study was partly supported by the National Science Foundation and Amazon Robotics.

(Video credit: MIT)