IMU-Based Indoor Localization for Construction Applications

Localization and tracking of resources on construction jobsites is an emerging area where the location of materials, labor, and equipment is used to estimate productivity, measure project's progress and/or enhance jobsite safety. GPS has been widely used for outdoor tracking of construction operations. However, GPS is not suitable for indoor applications due to the lack of signal coverage; particularly inside tunnels or buildings. Several indoor localization research had been attempted, however such developments rely heavily on extensive external communication network infrastructures. The developments also are susceptible to electromagnetic interference in noisy construction jobsites. This paper presents indoor localization system using a microcontroller equipped with an inertial measurement unit (IMU). The IMU contains a cluster of sensors: accelerometer, gyroscope and magnetometer. The microcontroller uses a direct cosine matrix algorithm to fuse sensors data and calculate non-gravitational acceleration using nine-degrees-of-freedom motion equations. Current position is calculated based on measured acceleration and heading, while accounting for growing error in speed estimation utilizing zero velocity update algorithm. Experimental results are presented to illustrate the relative effectiveness of the developed system, which is not only able to operate independently of any external aids and visibility conditions, but also is immune to electromagnetic interference.