title: Modeling high-level descriptions of real-life physical activities using latent topic modeling of multimodal sensor signals.
abstract: We propose a new methodology to model high-level descriptions of physical activities using multimodal sensor signals (ambulatory electrocardiogram (ECG) and accelerometer signals) obtained by a wearable wireless sensor network. We introduce a two-step strategy where the first step estimates likelihood scores over the low-level descriptions of physical activities such as walking or sitting directly from sensor signals and the second step infers the high-level description based on the estimated low-level description scores. Assuming that a high-level description of a certain physical activity may consist of multiple low-level physical activities and a low-level physical activity can be observed in multiple high-level descriptions of physical activities, we introduce the statistical concept of latent topics in physical activities to model the high-level status with low-level descriptions. With an unsupervised approach using a database from unconstrained free-living settings, we show promising results in modeling high-level descriptions of physical activities.
authors.affiliation: Viterbi School of Engineering, University of Southern California, Los Angeles, USA. kimsamue@usc.edu
authors.forename: Samuel
authors.initials: S
authors.lastname: Kim
authors.forename: Ming
authors.initials: M
authors.lastname: Li
authors.forename: Sangwon
authors.initials: S
authors.lastname: Lee
authors.forename: Urbashi
authors.initials: U
authors.lastname: Mitra
authors.forename: Adar
authors.initials: A
authors.lastname: Emken
authors.forename: Donna
authors.initials: D
authors.lastname: Spruijt-Metz
authors.forename: Murali
authors.initials: M
authors.lastname: Annavaram
authors.forename: Shrikanth
authors.initials: S
authors.lastname: Narayanan
mesh_terms: D056044:Actigraphy / Q000379:methods*; D000203:Activities of Daily Living; D000465:Algorithms; D003198:Computer Simulation; D004562:Electrocardiography / Q000379:methods*; D006801:Humans; D008954:Models, Biological; D009043:Motor Activity / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity