A Study on Anchor Placement and 3D Positioning Algorithm for UWB Application in Small Sites

Despite advancements in the industry, safety investments at small construction sites remain underinvested due to budget constraints that limit the employment of safety managers. The results of this study explore a cost-effective solution for accurate positioning of workers in hazardous areas using off-the-shelf smartphones and Ultra-Wide Band (UWB) technology, with a focus on small and medium-sized construction sites. We targeted a Three-Dimensional (3D) positioning error of less than 35 cm in an indoor space of 25–50 m². The results show that the spatial configuration of anchors and Mobile Terminals (MTs) has a significant impact on 3D accuracy, and in particular, deployment strategies with increasing height differences show a clearer reduction in error than differences in positional accuracy caused by differences between general least square algorithms. This highlights the importance of optimal anchor-MT placement, similar to Global Navigation Satellite System (GNSS) standards, to minimize Position Dilution of Precision (PDOP) values and improve positioning accuracy. We also suggest that adjusting the tetrahedral volume formed by anchors and MTs can solve complex site problems,improve worker positioning, and benefit safety management. This approach presents a practical and scalable way to improve safety protocols on small construction sites.