Semi-autonomous indoor positioning using MEMS-based inertial measurement units and building information

State-of-the-art indoor positioning systems are based on short-range wireless technologies such as ultra-wideband (UWB) and wireless local area network (WLAN). Additional information produced by a low-cost inertial measurement unit (IMU) or selected from low-grade floor plans is frequently used to improve the positioning accuracy. Therefore absolute and relative positioning systems (e.g. WLAN and IMU) are typically integrated using a Kalman filter (KF) or a particle filter (PF). In this case, all the buildings have to be equipped with a large number of transmitters and receivers which may render inoperable during emergency situations and induce substantial costs both in terms of setup and maintenance. Hence, in this paper we present and assess the prototype of a self-contained indoor positioning system. Our prototype consists of a micro-electro-mechanical system- (MEMS) based IMU and a mobile computer which includes a database with characteristic building information. A novel combination of methods is proposed to increase the distance between positions where absolute repositioning is still mandatory.