Model-based interpretation of floor vibrations for indoor occupant tracking

Information regarding occupant flows inside buildings is beneficial for applications such as thermal-load control, market research and security enhancement. Existing methodologies for occupant tracking involve data-driven techniques that rely either on radio-frequency devices, optical sensors or vibration sensors. Such data-driven techniques suffer from ambiguous interpretations, especially in presence of obstructions and varying floor rigidities. In this contribution, an occupanttracking strategy using footstep-induced vibrations is outlined. The goal is to incorporate information from physics-based models in the interpretation of vibration measurements. Using error-domain model falsification (EDMF) a single occupant is localized using the vibrations resulting from footstep impacts and using various shoe types. EDMF is a multiple-model approach that provides a set of candidate locations from an initial population of possible footstep locations. Model responses that contradict footstep-induced vibration measurements are rejected through incorporating several sources of uncertainty from measurements and modeling. Occupant-trajectory identification is then performed based on the candidate-location set for each detected footstep using a sequential analysis that combines information from consecutive footsteps. A full-scale case study is used to evaluate the methodology. Model-based occupant tracking that includes structural information and takes into account systematic errors and model bias has the potential to identify accurately single occupant locations in a full-scale structure.