Estimation of Measurement Uncertainty of the Real-Time Location System (RTLS) with Ultra-Wideband (UWB) Technology

Abstract

The need to control the real-time location of assets is increasingly relevant worldwide. The Ultra-wideband (UWB) technology is an IoT solution for real-time locating systems (RTLS). The location of the asset is obtained by the signal exchange between a wireless tag (asset) and fixed anchors. The tag interacts with the fixed anchors, defining its position through the distances obtained by trilateration. This data is sent to the server through the gateway. It is well-known that this process has several sources of errors. However, the measurement uncertainty assessment of UWB technology is an important topic regarding its scope of use. This paper presents a task-specific measurement uncertainty evaluation for the UWB positioning system, according to the ISO GUM. It aims to propose a method to support decision-making regarding the possible uses of UWB technology. The position provided by the UWB is compared with reference points using Cartesian coordinates that are measured with a total station, providing metrological reliability. Using the information from the estimated uncertainty, one can define the minimum tolerance interval associated with UWB technology for a given use. A case study demonstrates the method.

Keywords

• measurement uncertainty (U)
• E ¯ )%22%2C%22default_operator%22%3A%22AND%22%7D%7D%7D"> mean error (<named-content content-type="inline-formula"><inline-formula> <mml:math id="mm1"> <mml:semantics> <mml:mover accent="true"> <mml:mi>E</mml:mi> <mml:mo stretchy="false">¯</mml:mo> </mml:mover> </mml:semantics> </mml:math> </inline-formula></named-content>)
• portable coordinate metrology (PCM)
• real-time location system (RTLS)
• ultra-wideband (UWB)
• internet of things (IoT)