Janus, the Two-Faced Sensor, Uses Vibrations and Radar to Keep an Eye on Beehive Events
The Janus sensor, soon to be commercialized, aims to offer early warnings when swarming and robbing events are taking place.
Researchers at the University of Maine have developed a system, dubbed Janus after the two-faced god of Roman mythology, which uses a combination of vibration and radar sensors to track bees within and without a hive.
"A novel beehive monitoring sensor with two faces," the researchers write of Janus, demonstrating the reason for its Roman moniker. "This sensor is attached to the outside of a hive, near the hive entrance. The outward-looking sensor is a 24GHz continuous-wave Doppler radar for monitoring bee flying activity."
"The inward-looking sensor is a piezoelectric transducer. Unlike a conventional microphone that would pick up the sounds bees make, the piezoelectric transducer picks up the incidental vibrations transmitted by bee activity to the hive structure."
The idea behind Janus: To offer early warning of two key apiary events, swarming and robbing. "Swarming is a natural event during which about half the bee population leaves the hive to establish a new colony," the researchers note. "When swarming happens unexpectedly, however, the beekeeper would like to be alerted as soon as possible. At times of poor honey flow, bees from a stronger hive may attack a weaker hive and steal its honey. If successful, robbers can clean all the honey out of a hive in a few days."
Janus aims to offer an early warning to both events, and to be able to differentiate between the two — no mean feat, being created with low-cost parts including two Adafruit audio amplifier boards, a piezoelectric transducer, and a 24GHz Doppler radar. "The root-mean-square powers in concurrent radar and vibration measurements," the researchers note, "are shown to be highly correlated during honeybee swarming and robbing events."
In an interview with IEEE Spectrum, lead author Adjunct Professor Herbert M. Aumann confirmed the device's efficacy: The sensor detected all five swarm events from a deliberately-unsplit hive, and Aumann was able to prevent the swarming four of the five times — though the last, unsuccessful, attempt to stop the swarm was no fault of the sensor but rather Aumann being off-site having lunch at the time of the alert.
Aumann is planning to commercialize the technology, while the paper was published in the journal IEEE Sensors Letters under open-access terms.