The InvenSense MPU-6050 sensor contains an accelerometer and a gyroscope in a single chip. It is very accurate, this sensor is used in self balancing robots, drones, smartphones, etc. The sensor uses the I2C-bus to interface with microcontroller.
Beacons are mounted 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. Indoor Positioning System (IPS)