Newswise, Sonar systems for underwater imaging are crucial for ocean exploration. A discovery in this area is biomimetic sonar, which takes its cues from marine species like dolphins. The Tropical Marine Science Institute (TMSI) at the National University of Singapore (NUS) has made a small sonar that looks like a dolphin and has a new way of processing echo signals that makes it easier to see what’s going on underwater than the old way of processing signals.
The sonar considers the sparsity of objects, which improves the interpretation of sound echoes. This mode of processing is based on the idea that dolphins interpret their echoes using information about their surroundings that they already know, in addition to broadband sound pulses. The sonar created by the NUS team offers a superior trade-off between sonar-image quality, the number of sensors, and the size of the sensor array employed compared to existing sonars of comparable sizes and functions. When sensors are too few or dispersed, conventional techniques for processing sound echoes often fail. However, the NUS researchers’ sonar processing technique will be able to retrieve information and still provide clear images in such a situation.
In 2022, Communications Engineering released the report.
Sonar Interpretation with Dolphin Inspiration
The researchers discovered that dolphins could acoustically examine items underwater and choose compatible items visually. This proved that the shape of an item could be inferred from the sound echoes a dolphin produced off it. Then they captured the underwater echolocation of dolphins as they scanned an item.
The scientists created a biomimetic sonar that resembled a dolphin’s sonar based on their findings. The sonar, which has a width of approximately 25 cm and is about the size of a dolphin’s head, is designed to produce quick, abrupt click noises that resemble echolocation in dolphins. To broadcast sounds in various directions, three transmitters are employed. The scientists then used their sonar and the dolphin’s noises to analyze them in order to see what the echoes indicated about the form of the item.
The team developed an innovative program to work in conjunction with the hardware, allowing the sonar to enhance the depiction of the echoes. The researchers built the idea of sparsity into the sonar’s software on the premise that dolphins analyze their echoes using past knowledge. This is based on the assumption that the item only occupies a tiny portion of the region that was scanned.
“It makes sense to use past knowledge, such as the notion of sparsity. Humans often convert their perceptions of reality into expectations to hasten our deductions and judgements. According to Dr. Hari Vishnu, Senior Research Fellow at NUS TMSI, “for instance, in the lack of additional information, the human brain and visual system tend to believe that the light on an item in a picture will be descending from above”.
When the programme was able to see data from a dolphin’s sonar echoes while it was scanning an item and sonar waves generated by its small sonar, it proved to be useful. Images that were noisy were produced by processing both sonar echoes conventionally. But the innovative processing method produced clearer photos with improved resolution. The program is also operationally quick since it can provide visualisations from the sonar in only three clicks.
Applications and Future Work
Underwater commercial or military sonars may profit from the new sonar processing technique. For instance, it may be used to scan the ocean floor in search of things that might be helpful for navigating. Because of its small size, the sonar may also be placed to underwater robots for ocean research.
