Health and Medical Research Institute, National Institute of Advanced Industrial Science and Technology, 2217-14 Hayashi-cho, Takamatsu 761-0395, Kagawa, Japan.
Human Augmentation Research Center, National Institute of Advanced Industrial Science and Technology, 6-2-3 Kashiwanoha, Kashiwa 277-0882, Chiba, Japan.
Sensors (Basel). 2024 Aug 6;24(16):5096. doi: 10.3390/s24165096.
The accurate estimation of lower-limb joint angles and moments is crucial for assessing the progression of orthopedic diseases, with continuous monitoring during daily walking being essential. An inertial measurement unit (IMU) attached to the lower back has been used for this purpose, but the effect of IMU misalignment in the frontal plane on estimation accuracy remains unclear. This study investigated the impact of virtual IMU misalignment in the frontal plane on estimation errors of lower-limb joint angles and moments during walking. Motion capture data were recorded from 278 healthy adults walking at a comfortable speed. An estimation model was developed using principal component analysis and linear regression, with pelvic accelerations as independent variables and lower-limb joint angles and moments as dependent variables. Virtual IMU misalignments of -20°, -10°, 0°, 10°, and 20° in the frontal plane (five conditions) were simulated. The joint angles and moments were estimated and compared across these conditions. The results indicated that increasing virtual IMU misalignment in the frontal plane led to greater errors in the estimation of pelvis and hip angles, particularly in the frontal plane. For misalignments of ±20°, the errors in pelvis and hip angles were significantly amplified compared to well-aligned conditions. These findings underscore the importance of accounting for IMU misalignment when estimating these variables.
准确估计下肢关节角度和力矩对于评估骨科疾病的进展至关重要，在日常行走中持续监测是必要的。为此，人们将惯性测量单元 (IMU) 附着在腰部，但 IMU 在额状面的不对准对估计精度的影响仍不清楚。本研究调查了虚拟 IMU 在额状面的不对准对行走时下肢关节角度和力矩估计误差的影响。从 278 名以舒适速度行走的健康成年人那里记录了运动捕捉数据。使用主成分分析和线性回归开发了一个估计模型，以骨盆加速度为自变量，下肢关节角度和力矩为因变量。模拟了额状面中的虚拟 IMU 不对准-20°、-10°、0°、10°和 20°（五种情况）。在这些条件下估计和比较了关节角度和力矩。结果表明，额状面中虚拟 IMU 不对准的增加导致骨盆和髋关节角度的估计误差更大，尤其是在额状面。对于±20°的不对准，与对准良好的情况相比，骨盆和髋关节角度的误差明显放大。这些发现强调了在估计这些变量时考虑 IMU 不对准的重要性。
