title: Multimodal physical activity recognition by fusing temporal and cepstral information.
abstract: A physical activity (PA) recognition algorithm for a wearable wireless sensor network using both ambulatory electrocardiogram (ECG) and accelerometer signals is proposed. First, in the time domain, the cardiac activity mean and the motion artifact noise of the ECG signal are modeled by a Hermite polynomial expansion and principal component analysis, respectively. A set of time domain accelerometer features is also extracted. A support vector machine (SVM) is employed for supervised classification using these time domain features. Second, motivated by their potential for handling convolutional noise, cepstral features extracted from ECG and accelerometer signals based on a frame level analysis are modeled using Gaussian mixture models (GMMs). Third, to reduce the dimension of the tri-axial accelerometer cepstral features which are concatenated and fused at the feature level, heteroscedastic linear discriminant analysis is performed. Finally, to improve the overall recognition performance, fusion of the multimodal (ECG and accelerometer) and multidomain (time domain SVM and cepstral domain GMM) subsystems at the score level is performed. The classification accuracy ranges from 79.3% to 97.3% for various testing scenarios and outperforms the state-of-the-art single accelerometer based PA recognition system by over 24% relative error reduction on our nine-category PA database.
authors.affiliation: Viterbi School of Engineering, University ofSouthern California, Los Angeles, CA 90089, USA. mingli@usc.edu
authors.forename: Ming
authors.initials: M
authors.lastname: Li
authors.forename: Viktor
authors.initials: V
authors.lastname: Rozgica
authors.forename: Gautam
authors.initials: G
authors.lastname: Thatte
authors.forename: Sangwon
authors.initials: S
authors.lastname: Lee
authors.forename: Adar
authors.initials: A
authors.lastname: Emken
authors.forename: Murali
authors.initials: M
authors.lastname: Annavaram
authors.forename: Urbashi
authors.initials: U
authors.lastname: Mitra
authors.forename: Donna
authors.initials: D
authors.lastname: Spruijt-Metz
authors.forename: Shrikanth
authors.initials: S
authors.lastname: Narayanan
mesh_terms: D000054:Acceleration; D000465:Algorithms; D016477:Artifacts; D001185:Artificial Intelligence; D003627:Data Interpretation, Statistical; D004562:Electrocardiography / Q000295:instrumentation* / Q000706:statistics & numerical data; D006321:Heart / Q000502:physiology; D006801:Humans; D016014:Linear Models; D015233:Models, Statistical; D009043:Motor Activity / Q000502:physiology*; D016011:Normal Distribution; D010363:Pattern Recognition, Automated / Q000379:methods; D025341:Principal Component Analysis