Color-changing Robot Hides In Plain Sight

From detecting surrounding colors to changing patterns on display, a robot can now mimic chameleons’ uncanny ability of blending in with the surroundings.

AsianScientist (Aug. 11, 2021) – Blink and you’ll miss it—a team from South Korea has built a chameleon-inspired robot that instantly adapts its appearance to match the surroundings, effectively concealing it from view. The study was published in Nature Communications.

Whether predator or prey, the most effective disguise is often hiding in plain sight. Drawing inspiration from nature, scientists have been developing artificial camouflage technology, which could aid military operations or spark the next trend in color-changing fashion and homes.

But replicating nature’s camouflaging feats with technology isn’t just about changing colors. It also involves expressing dynamic patterns based on the background. If more parts are added to cover a wider array of patterns, however, controlling the system would prove increasingly complex. Moreover, the device may become bulky and impractical for use as a wearable.

To develop a robot that can mimic its surroundings, researchers from Seoul National University (SNU) and Hanyang University (HYU) combined an active feedback system with compact color-changing ‘skin’ on a chameleon model.

Similar to a suit with automatically adjustable displays, the skin is made of tiny liquid crystals that can change their orientation and reflect specific colors of light, much like those found in television screens. The material is easily tuned by small variations in temperature, making the choice of heaters vital to the system.

Led by SNU Professor Ko Seung Hwan and HYU Assistant Professor Hong Sukjoon, the team stacked silver nanowire heaters as temperature controllers. Integrated with sensors, the chameleon model detects the colors of its surroundings, prompting the heaters to warm up. The liquid crystals then rapidly exhibit the right colors to match the environment.

Since the flexible silver nanowires can sustain mechanical bending, the robot could crawl on all fours just like a real chameleon, with each part changing color as it crossed to backgrounds of varying colors.

The robot’s multilayered network of nanowires divides the skin into patches like distinct yet interconnected pixels, creating detailed designs. When appropriate combinations of built-in stripes and shapes are activated, the machine’s surface pattern effectively blends in with the surroundings.

But because it relies on temperature changes, the robot’s color transitions tend to be slower than the natural response and easily swayed by sudden fluctuations in the environment. To bring the technology up to speed, the team added an active feedback system to control the heaters more efficiently.

By dynamically adjusting the power used by the heaters, the device maintains the right temperature and changes colors on demand. While the feedback system helps stabilize the technology, it isn’t as perfect in extremely cold conditions, leaving room for further exciting advancements in this space.

According to the researchers, secondary heaters can improve the technology’s performance, but a viable pattern recognition system needs to be developed first to retrieve more complex information about the environment. With better pattern matching, they hope to build a fully autonomous system, deployable on a larger scale and adaptable to essentially any type of terrain.

“Fully automated color matching in accordance with the change in the local background, together with the exceptionally natural and rapid transition characteristics, verifies that our strategy possesses great potential as a next-generation artificial camouflage,” the authors wrote.

The article can be found at: Kim et al. (2021) Biomimetic chameleon soft robot with artificial crypsis and disruptive coloration skin..


Source: Seoul National University; Photo: Shutterstock.
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