Abstract
Wireless sensor networks (WSNs) and the Internet of Things (IoT) have been widely used in industrial, construction, and other fields. In recent years, demands for pedestrian localization have been increasing rapidly. In most cases, these applications work in harsh indoor environments, which have posed many challenges in achieving high-precision localization. Ultra-wide band (UWB)-based localization systems and pedestrian dead reckoning (PDR) algorithms are popular. However, both have their own advantages and disadvantages, and both exhibit a poor performance in harsh environments. UWB-based localization algorithms can be seriously interfered by non-line-of-sight (NLoS) propagation, and PDR algorithms display a cumulative error. For ensuring the accuracy of indoor localization in harsh environments, a hybrid localization approach is proposed in this paper. Firstly, UWB signals cannot penetrate obstacles in most cases, and traditional algorithms for improving the accuracy by NLoS identification and mitigation cannot work in this situation. Therefore, in this study, we focus on integrating a PDR and UWB-based localization algorithm according to the UWB communication status. Secondly, we propose an adaptive PDR algorithm. UWB technology can provide high-precision location results in line-of-sight (LoS) propagation. Based on these, we can train the parameters of the PDR algorithm for every pedestrian, to improve the accuracy. Finally, we implement this hybrid localization approach in a hardware platform and experiment with it in an environment similar to industry or construction. The experimental results show a better accuracy than traditional UWB and PDR approaches in harsh environments.
Highlights
With the development of wireless sensor networks (WSNs) and the Internet of Things (IoT) in industrial, construction, and other fields, accurate indoor localization technology for pedestrians is playing an increasingly important role
To address the problem presented above, this paper proposes a hybrid indoor localization system based on integrating pedestrian dead reckoning (PDR)/ultra-wide band (UWB) to achieve a high precision in harsh environments for pedestrians
Inertial navigation is an intuitive solution, but it is not suitable for tags for two reasons: (1) In a tag, limited by size and cost, the inertial measurement unit (IMU) is a microelectro mechanical system (MEMS), which makes the precision of IMU low, and (2) the strap-down inertial navigation system is too complicated to realize it in the tag node (TN)
Summary
With the development of wireless sensor networks (WSNs) and the Internet of Things (IoT) in industrial, construction, and other fields, accurate indoor localization technology for pedestrians is playing an increasingly important role. Multipath refraction is a common type of interference in harsh environments It means that an RF signal will be transmitted to the receiver through multiple paths, which causes the transmission time to be unreliable and unpredictable RSS superposition. RF-based indoor localization algorithms have problems achieving high-precision locations in harsh environments, in which cases some hybrid systems have been proposed. This refers to the addition of other auxiliary sensors in the localization system, such as ultrasonic, infrared ranging, and inertial measurement unit (IMU) sensors, etc. To address the problem presented above, this paper proposes a hybrid indoor localization system based on integrating PDR/UWB to achieve a high precision in harsh environments for pedestrians.
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