Asian Scientist Magazine (Aug. 23, 2022) — Engineers have been turning to nature for inspiration in designing newer technologies, such as an aquatic robot that mimics the movement of a stingray’s fins and the high-speed Shinkansen trains in Japan, whose front mimics a kingfisher’s beak, allowing the train to zoom past at high speeds without creating excessive noise as it travels through Japan’s railways.
Now, researchers from South Korea and the United States are looking at fiddler crabs to design a novel amphibious artificial vision system. Published in Nature Electronics, the research group have developed a camera and visualization system that has near 360-degree field-of-view and can function on land and underwater.
Fiddler crabs are semi-terrestrial creatures with eyestalks that are ellipsoidal in shape, allowing the eyestalks to rotate round easily, and compound eyes that allow light from any angle to converge at the same spot on the eyes’ retina, even when they are underwater. The fiddler crabs have evolved a wide field-of-view, which help them spot enemies from any angle and find other fellow fiddler crabs.
Professor Young Min Song, co-author of the paper from Gwangju Institute of Science and Technology, explains the motivation behind using the fiddler crab as inspiration for a new artificial vision system.
“Research in bio-inspired vision often results in a novel development that did not exist before,” says Song. “This, in turn, enables a deeper understanding of nature and ensures that the developed imaging device is both structurally and functionally effective.”
The team co-led by Song began by mimicking the shape and structure of the fiddler crab’s compound eyes. Flat micro-lenses with varying refractive indexes are integrated onto a comb-shaped silicon photodiode array, which is then mounted on a spherical structure. The micro-lenses allow light from multiple angles to focus squarely on a sensor that then processes the incoming light as an image.
This spherical ‘eye’ was tested on land and underwater by showing various images at different angles, to determine if it can detect these images. This was to determine if the micro-lenses can adjust and refocus the light on the sensor irrespective of the environment they are in.
Results were very promising. The ‘eye’ was able to detect these images successfully with no distortion underwater. Researchers also found the ‘eye’ has a near panoramic field-of-view – with a 300-degree view horizontally and 160-degree view vertically – in both air and in water.
“Our vision system could pave the way for 360° omnidirectional cameras with applications in virtual or augmented reality or an all-weather vision for autonomous vehicles,” says Song. This could also pave the way for surveillance cameras with a much wider field-of-view, allowing for the development of security cameras that can cover a wider range.
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Source: Gwangju Institute of Science and Technology; Photo: Thai National Parks/Flickr
The article can be found at Lee et al. (2022), An amphibious artificial vision system with a panoramic visual field.
