Localización de personas mediante sensores inerciales y su fusión con otras tecnologías

En el presente trabajo de Tesis se aborda el problema de la localización en entornos interiores utilizando sensores inerciales y su fusión con otras medidas para mejorar la estimación y limitar posibles derivas. Para ello, el algoritmo de localización propuesto se divide en tres partes: Una etapa de estimación del movimiento usando Pedestrian Dead Reckoning (PDR), un esquema de fusión de información que permite integrar múltiples tipos de medidas, aunque tengan relaciones no lineales, y la utilización de medidas externas (como la potencia de la señal de puntos de acceso WiFi, rangos a balizas UWB, GNSS, etc.) para limitar la deriva, proponiendo mejoras a cada una de ellas. Para mejorar el algoritmo PDR se propone la modificación del detector de apoyo utilizando un filtro de media sobre una ventana retardada. Para la estimación y corrección de errores se propone la utilización del filtro de Kalman Unscented (UKF) que simplifica los cálculos necesarios para la estimación y mejora la aproximación no lineal. Debido a la falta de información de la guiñada, una estimación PDR pura divergirá con el tiempo. Para aportar información de la orientación a la estimación se propone medir la rotación del campo magnético de acuerdo a las velocidades angulares observadas en el giróscopo. Se comprueba en varios experimentos que las mejoras evitan errores en la fase de apoyo, mejoran la estimación y disminuyen el efecto de la deriva de la orientación. Para fusionar la información del PDR con medidas externas se propone la utilización de dos esquemas: el primero, un filtro de límites que establece una distancia máxima entre 2 estimaciones, y el segundo un esquema basado en un filtro de partículas a dos etapas. El filtro de límites modifica la pdf (función de densidad de probabilidad) para evitar estimaciones muy distantes entre sí. Se comprueba que, al utilizar este método, se logra evitar la deriva un sistema PDR utilizando medidas UWB en otra parte del cuerpo. El esquema basado en un filtro de partículas utiliza la información de PDR para propagar las partículas y las medidas externas para actualizar los pesos de éstas. Se propone agregar el bias de la velocidad angular a los estados de las partículas para modelar el efecto del bias random walk (sesgo de camino aleatorio) del giróscopo. El filtro de partículas permite utilizar cualquier medida con una función de observación y una distribución de error, por lo que se estudian varios casos de estimaciones PDR fusionadas con medidas de sistemas WiFi, RFID, UWB y ZigBee. Los sistemas RF utilizados tienen un error de posicionamiento de 5 m (90 % de los casos) y la estimación PDR tiene un error creciente, pero al fusionar las estimaciones se logra un error inferior a 2 m (90 % de los casos). Por último, se utiliza el mapa del edificio para corregir las estimaciones y encauzarlas en las áreas caminables del edificio. Para ello se utiliza un método de eliminación de hipótesis (partículas) que atraviesan paredes. Este algoritmo se optimiza utilizando solo las paredes de la habitación en que se encuentra la partícula y se propone una sectorización de las operaciones para poder ser utilizada en MATLAB a tiempo real. Se demostró con señales reales que el algoritmo es capaz de auto localizar a una persona si el recorrido es no simétrico, obteniendo un nivel de error que dependerá del edificio, en nuestro caso cercano a 1 m. Si se utilizan medidas RF y el mapa, la estimación converge significativamente más rápido, y el nivel de error y el número de partículas necesarias (por ende, el tiempo de cómputo) disminuyen

Improving Inertial Pedestrian Dead-Reckoning by Detecting Unmodified Switched-on Lamps in Buildings

This paper explores how inertial Pedestrian Dead-Reckoning (PDR) location systems can be improved with the use of a light sensor to measure the illumination gradients created when a person walks under ceiling-mounted unmodified indoor lights. The process of updating the inertial PDR estimates with the information provided by light detections is a new concept that we have named Light-matching (LM). The displacement and orientation change of a person obtained by inertial PDR is used by the LM method to accurately propagate the location hypothesis, and vice versa; the LM approach benefits the PDR approach by obtaining an absolute localization and reducing the PDR-alone drift. Even from an initially unknown location and orientation, whenever the person passes below a switched-on light spot, the location likelihood is iteratively updated until it potentially converges to a unimodal probability density function. The time to converge to a unimodal position hypothesis depends on the number of lights detected and the asymmetries/irregularities of the spatial distribution of lights. The proposed LM method does not require any intensity illumination calibration, just the pre-storage of the position and size of all lights in a building, irrespective of their current on/off state. This paper presents a detailed description of the light-matching concept, the implementation details of the LM-assisted PDR fusion scheme using a particle filter, and several simulated and experimental tests, using a light sensor-equipped Galaxy S3 smartphone and an external foot-mounted inertial sensor. The evaluation includes the LM-assisted PDR approach as well as the fusion with other signals of opportunity (WiFi, RFID, Magnetometers or Map-matching) in order to compare their contribution in obtaining high accuracy indoor localization. The integrated solution achieves a localization error lower than 1 m in most of the cases

Neolithic land-use in the Dutch wetlands: estimating the land-use implications of resource exploitation strategies in the Middle Swifterbant Culture (4600-3900 BCE)

The Dutch wetlands witness the gradual adoption of Neolithic novelties by foraging societies during the Swifterbant period. Recent analyses provide new insights into the subsistence palette of Middle Swifterbant societies. Small-scale livestock herding and cultivation are in evidence at this time, but their importance if unclear. Within the framework of PAGES Land-use at 6000BP project, we aim to translate the information on resource exploitation into information on land-use that can be incorporated into global climate modelling efforts, with attention for the importance of agriculture. A reconstruction of patterns of resource exploitation and their land-use dimensions is complicated by methodological issues in comparing the results of varied recent investigations. Analyses of organic residues in ceramics have attested to the cooking of aquatic foods, ruminant meat, porcine meat, as well as rare cases of dairy. In terms of vegetative matter, some ceramics exclusively yielded evidence of wild plants, while others preserve cereal remains. Elevated δ15N values of human were interpreted as demonstrating an important aquatic component of the diet well into the 4th millennium BC. Yet recent assays on livestock remains suggest grazing on salt marshes partly accounts for the human values. Finally, renewed archaeozoological investigations have shown the early presence of domestic animals to be more limited than previously thought. We discuss the relative importance of exploited resources to produce a best-fit interpretation of changing patterns of land-use during the Middle Swifterbant phase. Our review combines recent archaeological data with wider data on anthropogenic influence on the landscape. Combining the results of plant macroremains, information from pollen cores about vegetation development, the structure of faunal assemblages, and finds of arable fields and dairy residue, we suggest the most parsimonious interpretation is one of a limited land-use footprint of cultivation and livestock keeping in Dutch wetlands between 4600 and 3900 BCE.NWOVidi 276-60-004Human Origin

Taphonomy, environment or human plant exploitation strategies?: Deciphering changes in Pleistocene-Holocene plant representation at Umhlatuzana rockshelter, South Africa

The period between ~40 and 20 ka BP encompassing the Middle Stone Age (MSA) and Later Stone Age (LSA) transition has long been of interest because of the associated technological change. Understanding this transition in southern Africa is complicated by the paucity of archaeological sites that span this period. With its occupation sequence spanning the last ~70,000 years, Umhlatuzana Rock Shelter is one of the few sites that record this transition. Umhlatuzana thus offers a great opportunity to study past environmental dynamics from the Late Pleistocene (MIS 4) to the Late Holocene, and past human subsistence strategies, their social organisation, technological and symbolic innovations. Although organic preservation is poor (bones, seeds, and charcoal) at the site, silica phytoliths preserve generally well throughout the sequence. These microscopic silica particles can identify different plant types that are no longer visible at the site because of decomposition or burning to a reliable taxonomical level. Thus, to trace site occupation, plant resource use, and in turn reconstruct past vegetation, we applied phytolith analyses to sediment samples of the newly excavated Umhlatuzana sequence. We present results of the phytolith assemblage variability to determine change in plant use from the Pleistocene to the Holocene and discuss them in relation to taphonomical processes and human plant gathering strategies and activities. This study ultimately seeks to provide a palaeoenvironmental context for modes of occupation and will shed light on past human-environmental interactions in eastern South Africa.NWOVidi 276-60-004Human Origin

Ways and Capacity in Archaeological Data Management in Serbia

Over the past year and due to the COVID-19 pandemic, the entire world has witnessed inequalities across borders and societies. They also include access to archaeological resources, both physical and digital. Both archaeological data creators and users spent a lot of time working from their homes, away from artefact collections and research data. However, this was the perfect moment to understand the importance of making data freely and openly available, both nationally and internationally. This is why the authors of this paper chose to make a selection of data bases from various institutions responsible for preservation and protection of cultural heritage, in order to understand their policies regarding accessibility and usage of the data they keep. This will be done by simple visits to various web-sites or data bases. They intend to check on the volume and content, but also importance of the offered archaeological heritage. In addition, the authors will estimate whether the heritage has adequately been classified and described and also check whether data is available in foreign languages. It needs to be seen whether it is possible to access digital objects (documents and the accompanying metadata), whether access is opened for all users or it requires a certain hierarchy access, what is the policy of usage, reusage and distribution etc. It remains to be seen whether there are public API or whether it is possible to collect data through API. In case that there is a public API, one needs to check whether datasets are interoperable or messy, requiring data cleaning. After having visited a certain number of web-sites, the authors expect to collect enough data to make a satisfactory conclusion about accessibility and usage of Serbian archaeological data web bases

Друга міжнародна конференція зі сталого майбутнього: екологічні, технологічні, соціальні та економічні питання (ICSF 2021). Кривий Ріг, Україна, 19-21 травня 2021 року

Second International Conference on Sustainable Futures: Environmental, Technological, Social and Economic Matters (ICSF 2021). Kryvyi Rih, Ukraine, May 19-21, 2021.Друга міжнародна конференція зі сталого майбутнього: екологічні, технологічні, соціальні та економічні питання (ICSF 2021). Кривий Ріг, Україна, 19-21 травня 2021 року