Bat-inspired palm-sized drone navigates fog and dodges obstacles
Researchers have built a bat-inspired palm-sized drone that can navigate dense fog and dodge obstacles. The aircraft, developed at Worcester Polytechnic Institute, uses ultrasonic echolocation rather than cameras or laser-based vision. It is designed for confined, dark and cluttered spaces where conventional autonomous drones can struggle.
The design draws on the bumblebee bat, a roughly 2-gram animal that lives in deep caves and uses ultrasound to detect objects as small as 0.1 mm. The drone sends short ultrasonic signals and listens for returning echoes after sound waves bounce off nearby surfaces. It then estimates obstacle locations in three dimensions and plans a path around them while continuing toward a target direction.
The approach addresses a core weakness in many aerial robots. Sensors such as LIDAR, RADAR, infrared depth cameras and vision systems can lose effectiveness in fog, dust, smoke, snow and low light. Those conditions are common in disaster zones and other hard-to-access areas, limiting the usefulness of larger or more sensor-heavy robots during search and rescue work.
Propeller noise posed a separate problem because it can overwhelm weak echoes. The team added a physical acoustic shield inspired by the ear cartilage of bumblebee bats and paired it with an artificial-intelligence denoising system called Saranga. The neural network reduces noise by tracking echo patterns over time, a strategy modeled on how bats process acoustic signals.
The prototype measures about 16 cm across and uses off-the-shelf motors, flight controllers and electronic speed controllers, along with a custom carbon-fiber frame and 3D-printed structural parts. It carries a Google Coral Mini development board and ultrasound sensors made by TDK Electronics, costs about $400 and uses about 1.2 mW of sensing power. Further gains in speed and miniaturization could make such drones useful for search and rescue, cave exploration and other missions where humans or larger aircraft cannot safely enter.