Indoor Position Estimation using NLoS Information by Wireless Distance Sensors

This paper proposes a method for non-line-of-sight (NLoS) position estimation utilizing wireless distance sensors. Recently, the accuracy of wireless distance sensors that use ultra-wideband (UWB) or ultrasonic technologies to measure the distance between two sensor devices has increased significantly. By placing these sensors in the environment, it is possible to precisely determine the position of mobile robots in indoor environments. Owing to reflections in the environment, these sensors have a large measurement error in NLoS conditions, limiting their applicability to environments that satisfy the line-of-sight (LoS) condition. This study aims to develop a stable method for estimating the position of mobile robots in indoor environments, including NLoS conditions, using wireless distance sensors. Experiments were conducted in two real environments: one with obstacles in front of the beacon and one with dynamic obstacles. In both cases, the combining 2D-LiDAR and wireless distance sensors using the proposed method considering NLOS was more accurate than the method considering LoS only.