Tiny “bat bots” use echolocation to navigate in complete darkness

Researchers at Worcester Polytechnic Institute have developed tiny “bat bots”—palm-sized drones that use echolocation to navigate in complete darkness, smoke, and adverse conditions where traditional drones fail. The breakthrough could revolutionize search and rescue operations, which often occur at night or in environments where visibility is severely compromised and power infrastructure has been damaged.

Why this matters: Current search and rescue drones require good lighting and manual operation, severely limiting their effectiveness during disasters when conditions are typically dark, smoky, or stormy and immediate response is critical for saving lives.

How it works: The miniature drones mimic bat behavior by using ultrasonic sensors to send out high-frequency sound pulses and interpret the echoes to detect obstacles and navigate safely.
• A small ultrasonic sensor, similar to those in automatic faucets, pulses sound waves and uses the returning echoes to “see” in complete darkness.
• During demonstrations, the drone successfully halted and backed away from a clear Plexiglas wall even with lights off and artificial fog swirling through the air.
• The team used artificial intelligence to teach the drone how to filter and interpret sound signals effectively.

Key advantages: These bat-inspired robots address major limitations of current search and rescue technology through their compact design and advanced perception capabilities.
• The drone fits in the palm of a hand and is made mostly from inexpensive hobby-grade materials.
• Unlike bulky, expensive traditional drones, these robots can operate in scenarios where current technology fails.
• They’re designed to be energy-efficient and deployable in swarms for autonomous search operations.

Development challenges: Creating functional echolocation required overcoming significant technical obstacles that initially interfered with the drone’s navigation system.
• Propeller noise interfered with the ultrasound system, requiring custom 3D-printed shells to minimize interference.
• The team had to develop AI algorithms to help the drone filter out irrelevant sounds and focus on navigation-critical echoes.

Real-world applications: Drones are already proving valuable in disaster response, but autonomous capabilities remain largely untapped.
• Recent deployments include finding flood victims on rooftops in Pakistan, locating a trapped California hiker behind a waterfall, and helping rescue mine workers trapped underground in Canada.
• Virginia Tech researcher Ryan Williams notes that “autonomous drones” deployment in search and rescue is “effectively nil,” highlighting the need for self-directed robotic systems.

What they’re saying: Lead researcher Nitin Sanket, assistant professor of robotics engineering at Worcester Polytechnic Institute, emphasizes the urgent need for technology that works in disaster conditions.
• “We all know that when there’s an earthquake or a tsunami, the first thing that goes down is power lines. A lot of times, it’s at night, and you’re not going to wait until the next morning to go and rescue survivors,” Sanket explained.
• “Currently, search and rescue robots are mainly operational in broad daylight. The problem is that search and rescues are dull, dangerous and dirty jobs that happen a lot of times in darkness.”

The reality check: Despite promising progress, the technology still has significant limitations compared to nature’s original design.
• Bats can detect objects as small as human hair from several meters away and can contract muscles to listen selectively to specific echoes.
• “Bats are amazing. We are nowhere close to what nature has achieved. But the goal is that one day in the future, we will be there and these will be useful for deployment in the wild,” Sanket acknowledged.