Indoor navigation using inertial sensors with additional radio-signal support is considered in this paper. The experimental results of data fusion between a navigation system, based on inertial measurement unit (IMU) and impulse-based UWB localization system, are presented. The IMU is additionally supported by a pedestrian step length estimations, barometer and electronic compass. The Ultra-Wideband part consists of receiver, carried by the person, and access points distributed in the scenario. The focus of the paper is put on hardware implementation and choice of the optimal data fusion technique. The presented results indicate the clear benefit of tightly coupled navigation filter, where the time differences of arrival of UWB signals are directly processed, without prior calculation of the localization solution.

Experimental results from data fusion of an inertial sensors based navigation system aided by a pedestrian step length estimations and an ultra-wideband system (UWB) are presented in this paper. One part of the presented experimental setup is a torso mounted inertial system with IMU, barometer and electronic compass with additional step length updates. The other part is the UWB system: The receiver is mounted on a backpack and measures the signal time of flight differences to several indoor base stations. In the paper the hardware setup, UWB implementation, step length updates as well as the data fusion filter are discussed. Finally results are presented, that show the advantage of a tightly coupled navigation filter, where range measurements are processed directly in the navigation filter.

In this paper a tightly coupled UWB/INS system for pedestrian indoor applications is presented. In indoor environments wireless signal outage and severe multipath propagation very often lead to ranging errors and make pure UWB-based localization barely possible. On the other hand inertial sensor based systems (INS) are known for their drift with time. The integration of those two systems will allow to profit from their advantages. For the sensor data fusion the tightly coupled approach and integrity monitoring are crucial factors for a robust implementation. One possibility is the Time of Arrival (ToA) approach where the user clock bias and drift are modeled and estimated in the navigation filter. The other possibility is the Time Difference of Arrival (TDoA) approach, where the range measurements are differenced totally eliminating the clock error. If user/transmitter clocks do not follow the clock drift model very well, it is better to apply the TDoA approach. For time of arrival applications, innovation based integrity monitoring is standard. However for the use of Time Difference of Arrival measurements (TDoA) in this paper an Innovation Based Integrity Monitoring (IBIM) method is presented. This is done to determine and omit all TDoA measurement combinations including the incorrect UWB receivers. This novel approach is verified in a simulation environment. A user trajectory and inertial data are provided by a custom developed pedestrian walk generator, based on real measurement data. The UWB data is generated by a wave propagation simulator for the given indoor trajectory.

This contribution considers the accuracy limits of ultra-wideband localization systems dedicated to large-scale applications. Industrial environments are known for being extremely difficult for wireless communication, mainly because of the high concentration of large metal objects, such as containers or machines; leading to strong multipath propagation. In this work a detailed 3D model of the warehouse is used for wave propagation simulations. In the simulation, the transmitter is moving along the predefined path and the receiver infrastructure consists of eight base stations. The aim is to model the tracking system and asses its accuracy - first, the upper bound of the accuracy is determined under ideal conditions and second, the precision estimation with the inclusion of effects of hardware non-idealities is done. Effects such as the influence of pulse detection methods, pulse shape and geometrical configuration of base-stations are investigated. The position calculation of the mobile beacon is realized using a Time Difference of Arrival approach. Eventually the accuracy of the obtained results and the theoretical limit are considered based on the dilution of precision evaluations.