A Hybrid Indoor Altimetry Based on Barometer and UWB

Abstract

Accurate altimetry is essential for location-based services in commercial and industrial applications. However, current altimetry methods only provide low-accuracy measurements, particularly in multistorey buildings with irregular structures, such as hollow areas found in various industrial and commercial sites. This paper innovatively proposes a tightly coupled indoor altimetry system that utilizes floor identification to improve height measurement accuracy. The system includes two optimized algorithms that improve floor identification accuracy through activity detection and address the problem of difficult convergence of z-axis coordinates due to indoor coplanarity by applying constraints to iterative least squares (ILS). Two experiments were conducted in a teaching building and a laboratory, including an irregular environment with a hollow area. The results show that our proposed method for identifying floors based on activity detection outperforms other methods. In dynamic experiments, our method effectively eliminates repeated transformations during the up- and downstairs process, and in static experiments, it minimizes the impact of barometric drift. Furthermore, our proposed altimetry method based on constrained ILS achieves significantly improved positioning accuracy compared to ILS, 1D-CNN, and WC. Specifically, in the teaching building, our method achieves improvements of 0.84 m, 0.288 m, and 0.248 m, respectively, while in the laboratory, the improvements are 2.607 m, 0.696 m, and 0.625 m.

An Enhanced Indoor Three-Dimensional Localization System with Sensor Fusion Based on Ultra-Wideband Ranging and Dual Barometer Altimetry

“…Ma’s research designed a 3D localization system for indoor mobile robots using four UWB anchors at different heights [ 31 ], compensating for the signal interference from patch-type UWB sensors, with decimeter-level accuracy meeting the application requirements. In areas with small height differences, a single BMP sensor shows insignificant pressure variations [ 6 ], and the accuracy is also greatly reduced by the effect of barometric drift. However, our proposed method using dual BMP sensors excels in height estimation, achieving an accuracy of ±0.05 m.…”

“…In indoor 3D localization, a substantial number of sensors are required to support the localization in larger buildings, and significant barometric changes can estimate floor levels [ 6 ]. For the size of the room environments, an indoor localization method that integrates SLAM and UWB technologies demonstrate notable accuracy [ 41 ].…”

“…Indoor localization can be divided into two categories according to the size of the localization area. The first category addresses larger areas, such as halls or multi-story buildings [ 5 , 6 ]. This scenario often requires multiple anchor points as references [ 7 ], or multi-sensor fusion [ 8 ].…”

“…By measuring atmospheric pressure changes, BMP sensors provide critical data for adjusting the vertical positioning in indoor localization systems, which is often flawed in UWB-only setups. However, the barometric pressure value at a given location can vary over time [ 6 ]. Outdoors, the shifting of high- and low-pressure weather systems can alter barometric pressure [ 28 ].…”