Uncertainties in inverse dynamics solutions: A comprehensive analysis and an application to gait
Uncertainties in inverse dynamics solutions: A comprehensive analysis and an application to gait
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DOI：
10.1016/j.gaitpost.2007.07.012
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发表时间：
2008-05-01
期刊：
影响因子：
2.4
通讯作者：
Zhang, Xudong
中科院分区：
文献类型：
--
作者：
Riemer, Raziel;Hsiao-Wecksler, Elizabeth T.;Zhang, Xudong
本文全面分析了由逆动力学推导出的关节转矩估计中的不确定性。该分析考虑了逆动力学解决方案的输入变量中大多数可量化的不准确性来源（即，由于皮肤运动伪影导致的身体分段参数估计、关节旋转中心位置、力板测量、运动捕捉系统测量和分段角度计算中的误差）。对不准确性的估计是根据现有文献和一组补充的实验数据综合得出的。该分析通过步态逆动力学分析进行说明和测试，其中记录了10名成人受试者的运动学和力板数据，并用于计算脚踝、膝盖、臀部、肘部、肩部和躯干底部的平面（屈伸）扭矩。结果表明，通过逆动力学推导出的转矩估计存在较大的不确定性（约为估计转矩大小的6-232%）；随时间变化的不确定性模式与扭矩分布不相似，并且越远的关节的幅度越小；造成这些不确定性的主要因素是估计的节段角度和体节参数的不准确性。实证检验还表明，由更保守（较小）的不准确估计集预测的不确定性与误差的统计（3 σ）界限相当。讨论了如何解释和改进逆动力学解的含义，以及当前工作的局限性。(c) 2007 Elsevier B.V.版权所有
This paper presents a comprehensive analysis of the uncertainties in joint torque estimates derived through inverse dynamics. The analysis considered most of the quantifiable sources of inaccuracy in the input variables for inverse dynamics solutions (i.e., errors in body segment parameter estimates, joint center of rotation locations, force plate measurements, motion capture system measurements, and segment angle calculations due to skin movement artifacts). Estimates of inaccuracies were synthesized from existing literature and from a complementary set of experimental data. The analysis was illustrated and tested via an inverse dynamic analysis of gait, in which kinematic and force plate data from 10 adult subjects were recorded and used to calculate the planar (flexion/extension) torques at the ankle, knee, hip, elbow, shoulder, and bottom of torso. The results suggested that the uncertainties in torque estimates derived through inverse dynamics can be substantial (6-232% of the estimated torque magnitude); the time-varying uncertainty patterns do not resemble the torque profiles, and the magnitudes are smaller for more distal joints; the main contributors to these uncertainties were identified to be the inaccuracies in estimated segment angles and body segment parameters. The empirical test also showed that the uncertainty predicted by a more conservative (smaller) set of inaccuracy estimates was comparable to the statistical (3 sigma) bound of the error. Implications in terms of how inverse dynamics solutions should be interpreted and improved, along with the limitations of the current work, are discussed. (c) 2007 Elsevier B.V. All rights reserved.