Improving Indoor Location Tracking Quality for Construction and Facility Management

Real-time location tracking systems (RTLS) for personnel and machinery in outdoor civil engineering environments quite often use commercially-available Global Navigation Satellite System (GNSS) technology. Although the GNSS is an important approach in outdoor positioning and logistics coordination, their signals are not able to penetrate buildings due to their signal strength. Despite some recent advances in research, reliable indoor navigation remains an unsolved problem. This work deals with a detailed study of the methods and approaches of indoor location tracking. The focus lies on systems based on Bluetooth Low Energy (BLE) technology that meet the specific requirements of construction sites and facility management. The authors develop a prototypical application with which measurements are taken using different BLE hardware. The experiments show that location tracking is only applicable to a limited extent using BLE technology and path loss model. There were great differences in the behavior of different devices observed since the environment greatly influences signal transmission. Due to the findings, the authors propose an alternative, holistic system for location tracking using BLE. It uses a systematic classification of the work space by positioning the BLE beacons according to the a-priori known spatial building structure, e.g., from a Building Information Model (BIM). By the relative observation of the received signal strengths of the individual beacons spread on a building floor, the calibration of the receivers is obsolete so that several different or alternative device types can be used together at the same time.