Miniature robots are becoming more popular due to their ability to access confined environments, making them ideal for search-and-rescue missions and high-value asset inspections. These small robots can also deform their bodies, which allows them to access cluttered terrains similar to those of insects and soft arthropods.
Motivated by this concept, a team of engineers at the University of Colorado-Boulder (CU Boulder) has designed CLARI (Compliant Legged Articulated Robotic Insect), a little, squishable robot that can passively change its shape to squeeze through narrow gaps – with a bit of inspiration from the world of bugs. The insect-scale quadrupedal robot also has the potential to aid first responders after major disasters in an entirely new way.
Several of these robots can easily fit in the palm of your hand, and each weighs less than a Ping Pong ball. Its four-legged body is roughly square, with one leg along each of its four sides, and is made up of four sections that are joined to one another by the robot’s flexible outer skin. The machine’s design allows engineers to mix and match its appendages, potentially giving rise to some wild and wriggly robots.
Each of CLARI’s legs functions almost like an independent robot – with its own circuit board and dual actuators that move the leg forward, backward, and side-to-side, similar to a human hip joint. Theoretically, that modularity might allow CLARI robots to take on a wide variety of shapes.
However, depending on how you squeeze CLARI, it can become wider, like a crab, or more elongated, like Jayaram’s old favorite, the cockroach. The robot can morph from about 34 millimeters (1.3 inches) wide in its square shape to about 21 millimeters (0.8 inches) wide in its elongated form.
The robot, currently with tethered electrical connections for power and control, is manufactured using laminate fabrication and assembled using origami pop-up techniques.
In future iterations, the researchers want to incorporate sensors into CLARI so that it can detect and react to obstacles. The group is also examining how to give the robot the right mix of flexibility and strength – a task that will only get more difficult with more legs, the team adds.
Ultimately, the team wants to develop shape-changing robots that don’t just move through a lab environment but a complex, natural space – in which the machines will need to bounce off obstacles like trees or even blades of grass or push through the cracks between rocks and keep going.
“When we try to catch an insect, they can disappear into a gap,” said Heiko Kabutz, a doctoral student in the Paul M. Rady Department of Mechanical Engineering. “But if we have robots with the capabilities of a spider or a fly, we can add cameras or sensors, and now we’re able to start exploring spaces we couldn’t get into before.”