Department of Mechanical Engineering, Center for Interdisciplinary Research in Rehabilitation and Social Integration, Université Laval, Quebec, QC G1V 0A6, Canada.
College of Engineering and Technology, American University of Middle East, Eqaila 5482+W2, Kuwait.
J Biomech Eng. 2020 Jul 1;142(7). doi: 10.1115/1.4046203.
The International Society of Biomechanics (ISB) has proposed standardized recommendations for recording human joint motion. The Euler angles-the orientation representation currently proposed by the ISB-have two drawbacks, namely, the issue of singularities (gimbal lock) and the difficulty to obtain clinical and interpretable orientation representation for compound movements. The orientation representation of the shoulder joint with the Euler angles is particularly challenging due to its broad range of motion. This paper proposes and evaluates an alternative orientation representation for shoulder movement based on the tilt-and-torsion representation, a method that aims at providing a more clinically interpretable solution for describing joint movements compared to the standard Euler angles. Three studies were performed to compare the different orientation representation methods. The first two studies consist in simulations of arm elevation in different planes. The third study is an experiment using inertial-measurement-units with one test subject performing shoulder elevation movements in different planes. The tilt-and-torsion representation is then compared with different Euler angle conventions. The results show that Euler angles are biased or clinically uninterpretable for compound movements. Conversely, tilt-and-torsion representation does not suffer from these limitations. Although not extensive, the experiments suggest that the tilt-and-torsion representation has the potential to better represent human movements and provide more clinically interpretable results than the Euler angles.
国际生物力学学会（ISB）已经提出了记录人体关节运动的标准化建议。Euler 角 - ISB 目前提出的方向表示法 - 有两个缺点，即奇点问题（万向节锁）和难以获得用于复合运动的临床可解释的方向表示法。由于肩部运动范围广泛，Euler 角的肩部关节方向表示法特别具有挑战性。本文提出并评估了一种基于倾斜和扭转表示的替代肩部运动方向表示法，与标准 Euler 角相比，该方法旨在为描述关节运动提供更具临床可解释性的解决方案。进行了三项研究来比较不同的方向表示方法。前两项研究包括在不同平面上模拟手臂抬高。第三项研究是一项使用惯性测量单元的实验，一名测试对象在不同平面上进行肩部抬高运动。然后将倾斜和扭转表示法与不同的 Euler 角约定进行比较。结果表明，对于复合运动，Euler 角是有偏差的或临床不可解释的。相反，倾斜和扭转表示法没有这些限制。尽管实验范围不大，但实验表明，倾斜和扭转表示法有可能比 Euler 角更好地表示人体运动并提供更具临床可解释性的结果。
