Scientists at the Korea Advanced Institute of Science and Technology (KAIST) have discovered an easy and efficient way to take out drones – sound. Every drone makes use of a gyroscope to track its orientation and tilt, which allows it to make movements and remain stable while in the air. If that gyroscope is deactivated, however, the drone cannot remain in the air for long.
In their study, KAIST scientists were able to target the on-board MEMS gyroscope using very intense and loud (140 decibels) sound waves. By mounting a speaker directly to the housing of the drone, they could cause drones to crash. However, drones don’t usually have speakers attached to them. Upon further investigation they found that, if loud enough, directional speakers could disable drones from a distance of up to 120 feet. The drone takes off normally, but when the right noise is played through the speaker, it smacks into the ground.
What the researchers discovered was that most drones have cheaper, consumer grade gyroscopes that will resonate at their native frequencies, which fall within the audio frequency band of 20 Hz – 20 KHz in many cases. When subjected to audio signals, the gyros start to resonate and vibrate, and incorrectly over-compensate the drone’s rotors, causing it to fail and sending it crashing to the ground. Gyroscopes that had resonant frequencies in the audible range (below 20 kHz) were affected considerably more along the X-axis and Y-axis than along the Z-axis. In contrast, the gyroscopes that resonated in the ultrasound range (above 20 kHz) were affected in the Z-axis direction only.
Since bulk-acoustic mode resonators operate at a native frequency an order of magnitude higher (2 – 10MHz) due to greater structural stiffness, BAW MEMS™ gyros are not susceptible to a sound wave attack and would continue to operate normally. To learn more about BAW MEMS, go to:
- BAW MEMS gyroscope products
- The technology behind BAW MEMS that makes it immune to shock and vibration
The KAIST paper, entitled “Rocking Drones with Intentional Sound Noise on Gyroscopic Sensors,” was presented at the 24th USENIX Security Symposium in Washington, D.C., August 12-14, 2015.