Ralph Simon, Stefan Rupitsch, Markus Baumann, Huan Wu, Herbert Peremans, Jan Steckel. Bioinspired sonar reflectors as guiding beacons for autonomous navigation. Proceedings of the National Academy of Sciences Jan 2020, 201909890; DOI: 10.1073/pnas.1909890117

Significance
“Artificial landmarks are widely used for autonomous navigation of robots and driverless cars. Landmarks can be simple traffic signs, radar retroreflectors, infrared lights, or barcodes depending on the sensors of the autonomous device. However, for in-air sonar sensors, one of the most applied sensors, artificial landmarks have never been used. Yet, in nature we find perfect examples for sonar landmarks. Bat-pollinated flowers guide and attract bats with acoustically conspicuous floral reflectors, detectable even in cluttered surroundings. We present how landmarks inspired by these floral forms can be used as guiding beacons and even be used as local source of information. Bioinspired landmarks can be very efficient tools, opening doors for new applications of sonar sensors and safer autonomous navigation.”

Abstract
“Sonar sensors are universally applied in autonomous vehicles such as robots and driverless cars as they are inexpensive, energy-efficient, and provide accurate range measurements; however, they have some limitations. Their measurements can lead to ambiguous estimates and echo clutter can hamper target detection. In nature, echolocating bats experience similar problems when searching for food, especially if their food source is close to vegetation, as is the case for gleaning bats and nectar-feeding bats. However, nature has come up with solutions to overcome clutter problems and acoustically guide bats. Several bat-pollinated plants have evolved specially shaped floral parts that act as sonar reflectors, making the plants acoustically conspicuous. Here we show that artificial sonar beacons inspired by floral shapes streamline the navigation efficacy of sonar-guided robot systems. We developed floral-inspired reflector forms and demonstrate their functionality in 2 proof-of-principle experiments. First we show that the reflectors are easily recognized among dense clutter, and second we show that it is possible to discern different reflector shapes and use this identification to guide a robot through an unfamiliar environment. Bioinspired sonar reflectors could have a wide range of applications that could significantly advance sonar-guided systems.”

Ralph Simon, Stefan Rupitsch, Markus Baumann, Huan Wu, Herbert Peremans, Jan Steckel. Bioinspired sonar reflectors as guiding beacons for autonomous navigation. Proceedings of the National Academy of Sciences Jan 2020, 201909890; DOI: 10.1073/pnas.1909890117