In a Tight Spot

These days, robots are becoming ever more capable and are stepping out of laboratories and factories into the wider world, with all of its complexities and challenges. These technological advancements are transforming various industries and domains, offering innovative solutions that were once deemed the stuff of science fiction. From healthcare to agriculture, disaster response to exploration, robots are proving their mettle in tackling a diverse array of tasks that were previously considered too dangerous, dull, or demanding for humans alone.

In healthcare, robots are assisting surgeons with unprecedented precision during intricate procedures, leading to shorter recovery times and reduced risks for patients. Additionally, robots are taking on the role of caregivers for the elderly and individuals with disabilities, providing companionship and aiding with daily tasks to improve their quality of life. In agriculture, robots equipped with advanced sensors and machine learning algorithms are revolutionizing farming practices by autonomously planting, tending, and harvesting crops, resulting in higher yields and reduced resource wastage.

However, amidst these remarkable advancements, a limitation has become apparent: the fixed body shapes of today's robots. While they excel in predefined environments, they often struggle to navigate tight spaces or complex terrains that are inherent to real-world situations. For instance, disaster-stricken areas or cluttered urban landscapes pose significant challenges for robots with rigid bodies. The need for more adaptable and versatile robotic designs has spurred researchers to explore innovative solutions inspired by nature, such as snake-like robots that can slither through confined spaces or quadrupedal robots that can traverse diverse landscapes with ease.

A pair of researchers at the University of Colorado Boulder have taken their inspiration to solve this problem from another source — creepy-crawlies like cockroaches and spiders. Intent on mimicking insects’ flexibility and ability to squeeze into tight places, they have built a robot called CLARI (Compliant Legged Articulated Robotic Insect). CLARI is a tiny legged robot that can passively shape-shift to fit into the tightest of places.

The 2.59 gram (lighter than a table tennis ball) quadrupedal robot is powered by eight custom-fabricated piezoelectric actuators. The body design is based on the Harvard Ambulatory MicroRobot (HAMR) platform, but with some important modifications. CLARI was designed to be able to change its shape to fit through tight spaces, and those shape changes result from the engineering of the leg modules.

The legs were created with a modular design, in which the components (actuation, transmission, and power delivery) are fully independent from the other legs, to allow for multiple body shape configurations. Also, the actuators were vertically aligned with the leg modules (unlike the stock HAMR design), which gives them the ability to become very compact when needed. A custom, streamlined piezoelectric actuator design further adds to the flexibility of CLARI’s body shape.

Normally in a square-shaped configuration, when CLARI encounters obstacles that block its movement, it can transform itself to long and slender or wide configurations, with the height of the legs also capable of changing to fit into tight spaces. The present prototype design is somewhat hindered in its capabilities because it is tethered by wires for power and control signals, but the team expects to develop future versions of CLARI that are wireless and fully self-contained.

Also of note is the fact that the robot is highly modular, so the quadrupedal form factor is not fixed. It could be modified to have different numbers of legs, perhaps eight to make a spider-like robot, or many more to make a complex crawler that can handle difficult terrain. The team believes that this flexibility will give rise to new types of robots that can aid first responders after disasters, for example. But first, CLARI will have to prove itself in the real world — so far it has only been tested in laboratory conditions.

Can't get enough robots? Check out this self-destructing robot, this one that can help you get dressed, and this open source robot foot that can sense different types of terrain in an unusual way.