Fog, smoke, and darkness pose significant challenges for human rescue teams during emergencies. To address these conditions, Nitin Sanket and his team at Worcester Polytechnic Institute (WPI) explore nature’s solutions by designing tiny drones that draw inspiration from bats’ echolocation abilities. The team aims to create mobile robots that can search areas standard aircraft cannot reach, particularly in hazardous or low-visibility scenarios. Drones equipped with advanced navigation are expected to play a practical role in disaster response, while minimizing operation costs and increasing accessibility for emergency missions.
Sanket’s research stands out from earlier approaches that relied heavily on expensive lidar-based or vision-based drones. Efforts reported in previous years demonstrated prototype robots using optical cameras or thermal imaging sensors but encountered size, power, and cost limitations. Sanket’s direction toward sound-based navigation seeks to mitigate these obstacles, while integrating custom hardware and software improves reliability in noisy or visually obstructed environments. The shift from relying on vision to sound-based sensing represents a notable development compared to established search and rescue drone practices.
How Do WPI’s Tiny Drones Mimic Bats’ Echolocation?
Sanket and his group focus on replicating bats’ navigation by incorporating ultrasonic echolocation into the drones. These aerial robots can operate in conditions with little or no visual information, expanding the areas accessible during search and rescue. At less than 100 millimeters in size and weighing under 100 grams, the prototypes pair metamaterial-based hardware with low-power sensors to enhance sound detection while minimizing interference from drone propellers or surrounding noise.
What Challenges Do Engineers Face Creating Sound-Based Robots?
Designing drones that use sound brings obstacles; ultrasound’s resolution can struggle with identifying small features and is susceptible to noise from mechanical components. WPI’s team addresses this by leveraging smart geometric structures and collaborating with sensor manufacturers for custom, low-power ultrasonic emitters. Sanket said,
“Smart design lets it modulate the sound. Think of flat plastic versus a squiggly design, which reflects less — think of the foam used in sound baffling.”
These material and design choices emulate the way bats and humans shape their ears to better gather sound.
Can AI Improve Drone Performance in Harsh Conditions?
The group integrates artificial intelligence with a hierarchical reinforcement learning system, teaching the drones to interpret ultrasonic signals and avoid obstacles autonomously. Sanket emphasizes the need for processors to operate independently without reliance on cloud computing. He explained,
“I first tell students, it has to work on the robot — there is no cloud, no infrastructure. We’re figuring it out as we go.”
This enables swift, low-latency decision-making during urgent rescue operations.
Sanket’s work, supported by a National Science Foundation grant, anticipates that fleets of these miniature drones will perform effective searches where larger systems or vision-dependent robots are less reliable. There is an expectation that these drones will gradually incorporate sensor fusion—blending ultrasound with inertial measurement units—to detect not only obstacles but potentially survivors’ heartbeats. The principles of bio-inspired acoustic navigation could also find roles in fields such as autonomous vehicles or environmental monitoring, highlighting the adaptability of this technology.
Practical challenges remain as engineers develop robust sound-based sensing for miniaturized robots, and comparisons with conventional lidar or camera-based systems underline both the promise and current limitations of echolocation in robotics. For search and rescue, the path toward low-cost, autonomous solutions continues as teams refine hardware, learning systems, and operational protocols for unstructured terrains. Organizations seeking to deploy such drones may consider the advantages of resilience in limited-visibility conditions and the potential for reduced reliance on costly infrastructure. As miniaturized, acoustically guided robots evolve, responders can expect new tools for addressing emergencies in complex environments.
