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Journal ArticleDOI

Optimal digital filtering requires a different cut-off frequency strategy for the determination of the higher derivatives

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TLDR
Four different filtering and differentiation sequences for the calculation of the higher derivatives from noisy displacement data when using a second-order Butterworth filter and first-order finite differences are investigated, indicating that the conventional strategy has to be reconsidered and modified.
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This article is published in Journal of Biomechanics.The article was published on 1997-08-01. It has received 111 citations till now. The article focuses on the topics: Frequency domain & Time domain.

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Citations
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Estimating velocities and accelerations of animal locomotion: a simulation experiment comparing numerical differentiation algorithms

TL;DR: A computer simulation experiment to explore the efficacy of ten numerical differentiation algorithms to reconstruct velocities and accelerations accurately from displacement data and presents a much more optimistic role for numerical differentiation than suggested previously.
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Whole body inverse dynamics over a complete gait cycle based only on measured kinematics

TL;DR: The model gave reasonably good estimates of sagittal plane ground forces and moment; however, the estimates in the other planes were less good, which the authors believe is largely due to their small magnitudes in comparison to the sagittal forces and Moment.
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Validity and reliability of triaxial accelerometers for inclinometry in posture analysis

TL;DR: Inclinometry data have been obtained from triaxial accelerometers based on uniaxial solid-state accelerometers used in conjunction with a computer program to perform co-ordinate transformations, and it is shown that spherical co-ordinates can be used to present the inclinometryData.
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Influence of body segments’ parameters estimation models on inverse dynamics solutions during gait

TL;DR: Evidence is provided that using multiple regression BSP estimation functions derived from Zatsiorsky and Seluyanov should be recommended to assess joint kinetics.
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Questionnaire versus direct technical measurements in assessing postures and movements of the head, upper back, arms and hands.

TL;DR: It seems difficult to construct valid questionnaires on mechanical exposure for establishing generic exposure-response relations in epidemiologic studies, especially cross-sectional ones, and direct technical measurements may be preferable.
References
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Measurement and reduction of noise in kinematics of locomotion.

TL;DR: A spectral analysis of the trajectories of 7 body markers in the saggital plane, and of the knee angle as determined by 4 of these markers, indicates that, for the marker trajectories, 99·7 per cent of the signal power lies below the 8th harmonic.
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Fitting of Mathematical Functions to Biomechanical Data

TL;DR: A method is presented to decide the order a polynomial or Fourier series best represents a set of biomechanical data points, with regard to the calculation of the first and second derivatives of the data.
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Comparison of the performance of 3D camera systems

TL;DR: The accuracy and processing time of 11 commercially available 3D camera systems were tested to evaluate their performance in clinical gait evaluation to estimate the processing time for calculating 3D coordinates from data obtained during normal gait.
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An assessment of derivative determining techniques used for motion analysis.

TL;DR: The study was conducted to compare film generated acceleration curves with the analog acceleration curves of single segment movements, and found digital filtering combined with a first order finite difference technique produced acceleration data very closely approximating the analog signals.