title: Measurement of Dynamic Joint Stiffness from Multiple Short Data Segments.
abstract: This paper presents our new method, Short Segment-Structural Decomposition SubSpace (SS-SDSS), for the estimation of dynamic joint stiffness from short data segments. The main application is for data sets that are only piecewise stationary. Our approach is to: 1) derive a data-driven, mathematical model for dynamic stiffness for short data segments; 2) bin the non-stationary data into a number of short, stationary data segments; and 3) estimate the model parameters from subsets of segments with the same properties. This method extends our previous state-spacework by recognizing that initial conditions have important effects for short data segments; consequently, initial conditions are incorporated into the stiffness model and estimated for each segment. A simulation study that faithfully replicated experimental conditions delineated the range of experimental conditions for which the method can successfully identify stiffness. An experimental study on the ankle of a healthy subject during a torque matching tasks demonstrated the successful estimation of dynamic stiffness in a slow, time-varying experiment. Together, the simulation and experimental studies demonstrate that the SS-SDSS method is a valuable tool to measure stiffness in functionally important tasks.
authors.forename: Kian
authors.initials: K
authors.lastname: Jalaleddini
authors.forename: Mahsa A
authors.initials: MA
authors.lastname: Golkar
authors.forename: Robert E
authors.initials: RE
authors.lastname: Kearney
mesh_terms: D003198:Computer Simulation; D055119:Elastic Modulus / Q000502:physiology; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008954:Models, Biological; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019415:Torque; D014783:Viscosity; D055815:Young Adult