In an Even Tighter Spot

Robots are being used more and more in search and rescue operations, revolutionizing the way emergency situations are handled. These machines are often better suited than human rescuers for navigating hazardous locations and tight spaces, where human access may be limited or dangerous. Equipped with advanced sensors and cameras, these robots can penetrate through debris, collapsed structures, and other dangerous environments, providing real-time data and imagery to help locate survivors. Their ability to withstand extreme conditions, such as fires, earthquakes, and hazardous materials, makes them indispensable in situations where human intervention would be too risky.

One of the main issues with using robots in search and rescue operations is their present design limitations. Many existing robots are rigid, which makes it difficult for them to navigate through tight spaces and complex terrain. While some more flexible robots have been developed, they are often bulky, making it too difficult to access confined areas. As a result, there is a growing need for small, flexible robots that can maneuver through narrow passages, crevices, and other constrained environments where traditional robots struggle.

Researchers at the University of Colorado Boulder have been hard at work to address this technological gap. A few months ago, they announced the development of CLARI, a tiny legged robot that was inspired by cockroaches and spiders, and can passively shape-shift to fit into some very tight places. Building on that work, they have just announced an updated robot called mCLARI (mini Compliant Legged Ambulatory Robotic Insect). At 20 millimeters in length and just 0.97 grams in weight, mCLARI is 60% of the length and 38% of the mass of the original CLARI. In spite of these shrinking dimensions, mCLARI retains 80% of the actuation power of its big brother.

mCLARI was designed with a carbon fiber square frame that serves as the body, and four legs that are articulated by a set of eight piezoelectric actuators. A pair of actuators, with a spherical five-bar linkage serving as the transmission, controls the action of each leg. The leg modules are connected by laminates, which allows for the planar motions that enable lateral shape deformation for shape-shifting. While a lot of hardware has been loaded into this tiny package, it is worth noting that mCLARI relies on cable tethers for both power and control signals, which would severely restrict its use in real-world search and rescue operations.

The new, improved robot can walk with a variety of gaits at a speedy pace of three body lengths per second. As it moves, mCLARI can bend and squeeze to fit through tight spaces and around sharp corners. The robot can even shift its shape as it changes direction to push its way through the most challenging conditions.

A series of experiments were conducted to assess how well the mCLARI platform would operate in different situations. The robot was tested on a number of surfaces and found to move the fastest on rough surfaces like sandpaper. It was also demonstrated that mCLARI can easily squeeze through narrow areas smaller than the size of the robot’s body. Impressively, getting through sharp turns while squeezed into tight spaces also proved to be no problem.

Looking ahead, the team intends to explore techniques that might give them active control of the robot’s shape-shifting. They also plan to look into building the control mechanism into the robot, such that the cable tether will no longer be needed. These enhancements would go a long way toward making the platform practical for real-world use.