title: Upper limb joint angle tracking with inertial sensors.
abstract: Wearable inertial systems have recently been used to track human movement in and outside of the laboratory. Continuous monitoring of human movement can provide valuable information relevant to individual's level of physical activity and functional ability. Traditionally, orientation has been calculated by integrating the angular velocity from gyroscopes. However, a small drift in the measured velocity leads to large integration errors that grow with time. To compensate for that drift, complementary data from accelerometers are normally fused into the tracking systems using the Kalman or extended Kalman filter (EKF). In this study, we combine kinematic models designed for control of robotic arms with the unscented Kalman filter (UKF) to continuously estimate the angles of human shoulder and elbow using two wearable sensors. This methodology can easily be generalized to track other human joints. We validate the method with an optical motion tracking system and demonstrate correlation consistently greater than 0.9 between the two systems.
authors.affiliation: Biomedical Signal Processing Laboartory, Department of Electrical and Computer Engineering at Portland State University, Portland, Oregon, USA. mahmoud@pdx.edu
authors.forename: Mahmoud
authors.initials: M
authors.lastname: El-Gohary
authors.forename: Lars
authors.initials: L
authors.lastname: Holmstrom
authors.forename: Jessie
authors.initials: J
authors.lastname: Huisinga
authors.forename: Edward
authors.initials: E
authors.lastname: King
authors.forename: James
authors.initials: J
authors.lastname: McNames
authors.forename: Fay
authors.initials: F
authors.lastname: Horak
mesh_terms: D000054:Acceleration; D000465:Algorithms; D001132:Arm / Q000502:physiology*; D053587:Arthrometry, Articular / Q000295:instrumentation / Q000379:methods*; D003198:Computer Simulation; D006801:Humans; D007596:Joints / Q000502:physiology*; D008954:Models, Biological; D016059:Range of Motion, Articular / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity