Real-time handheld indoor positioning device based on RFID Heron-bilateration location estimation and IMU angular-driven navigation reckoning

A real-time handheld indoor positioning device is developed, featuring 2 novel perfectly complementary positioning methods: 1) RFID Heron-bilateration location estimation, based on external RFID infrastructure, and 2) IMU angular-driven navigation reckoning, based on internal IMU module. At first, 2 or multiples of 2 active RFID tags as infrastructure landmarks are deployed along the surrounding walls in a single indoor space or room. After the infrastructure landmarks are set up, the handheld indoor positioning device begins to connect to the Bluetooth-based RFID reader by pairing with Bluetooth ID of the RFID reader. Then, on the screen of the handheld indoor positioning device, red landmarks on the 2D indoor map represents pre-deployed active RFID tags. When moving, the targeted handheld indoor positioning device keeps estimating the relative location through external RFID infrastructure and keeps reckoning the inertial navigation through internal IMU module. Furthermore, this work proposes and develops Kalman-filter drift removal, linear-like RSSI-to-distance transformation, RFID Heron-bilateration location estimation, and IMU angular-driven navigation reckoning, to improve the accuracy and reliability of positioning. Finally, the screen of the handheld indoor positioning device can show the location and orientation indications of the targeted user on the 2D indoor map accurately and immediately.