The MaxBotix low voltage MB1010 LV-MaxSonar-EZ1 offers very short to long-range detection and ranging, in an incredibly small package with ultra low power consumption. The MaxSonar-EZ1 detects objects from 0" to 254".
Mount beacons on walls or ceilings to measure distance to other beacons and “hedgehog” using ultrasonic pulses. They communicate with router wirelessly in ISM band. Powered by LiPo battery or USB. The beacon has a built in Inertial Measurement Unit (IMU).