A Low-Power Connected 3-D Indoor Positioning Device

Indoor positioning has emerged as an important research field with a host of methods being investigated. However, an accurate and versatile positioning system is yet to emerge. In this article, we present an indoor positioning device based on 2-D infrared laser beams and a novel positioning algorithm. The device can be mounted on an object being tracked as a tag and uses the infrared laser beams emitted by two lighthouse base stations to calculate its location. It captures the laser beams using an infrared photodiode, digitizes the captured signals using a light to digital converter, and carries out positioning calculations in a low-power microcontroller on board the device. The position coordinates are then transferred to a smartphone via a Bluetooth low-energy (BLE) transceiver once every second. The device is powered by a 3.7-V LiPo battery and can operate for a period of 15 h using a 300-mAh battery. The enclosed device is cylindrical and has a height of 7 mm and a diameter of 23 mm, thus making it easily mountable on the object being tracked. The experimental results show that the device has an absolute total accuracy of 127 mm when the lighthouse base stations are placed 10 m apart. This device can be effectively used in single-room positioning of objects in various applications, including tracking goods in storerooms, equipment in hospitals, robot navigation, and in research on the movement of small animals.