Kanega Shun, Muraoka Yoshihiro
Faculty of Human Sciences, Waseda University, Tokorozawa, Saitama, Japan.
National Hospital Organization Murayama Medical Center, Musashimurayama, Tokyo, Japan.
Jpn J Compr Rehabil Sci. 2024 May 30;16:19-29. doi: 10.11336/jjcrs.16.19. eCollection 2025.
Kanega S, Muraoka Y. Real-Time Estimation of Lower Limb Posture and Joint Angles Using Wearable IMUs: Reproduced Hemiparetic and Normal Gait. Jpn J Compr Rehabil Sci 2025; 16: 19-29.
A low-computational-load posture estimation method was employed, assuming integration into a functional electrical stimulation (FES) device, to estimate thigh and shank inclination angles as well as the knee joint angle during gait. The accuracy and processing time of the method were evaluated to assess its practical feasibility.
Two inertial measurement units (IMUs) were mounted on the lateral thigh and shank. Two healthy adults performed level-ground gait, including normal gait and gait reproducing the characteristics of circumduction gait, which is typically observed in individuals with post-stroke hemiparesis. A custom gait pacemaker was developed to replicate the spatiotemporal asymmetry of hemiparetic gait. Posture estimation in the sagittal and frontal planes was performed on a microcontroller using a low-computational-load Madgwick filter, and the processing time was recorded. The estimation accuracy was assessed by comparing the results with optical motion capture data using root mean square error (RMSE) and cross-correlation analysis.
The average total processing time, including sampling, posture estimation, and stimulation control, was 6.8 ms. The RMSE of sagittal plane posture angles was less than 4° in all cases, suggesting estimation accuracy comparable to previous studies. For the frontal plane posture angles, the estimation accuracy was relatively high during the reproduced circumduction gait, indicating that the system effectively captured the circumduction motion. Conversely, the accuracy tended to be lower during normal gait.
Compared with previous studies, the posture estimation method used in this study, which employed the Madgwick filter, was able to estimate posture without compromising accuracy. The entire process, including sampling, posture estimation, and stimulation control, was completed within 10 ms, reflecting the feasibility of real-time processing at 100 Hz.
金贺 S，村冈 Y。使用可穿戴惯性测量单元实时估计下肢姿势和关节角度：再现偏瘫和正常步态。《日本综合康复科学杂志》2025 年；16：19 - 29。
采用一种计算负荷低的姿势估计方法，假定将其集成到功能性电刺激（FES）设备中，以估计步态期间大腿和小腿的倾斜角度以及膝关节角度。评估该方法的准确性和处理时间，以评估其实际可行性。
在大腿外侧和小腿上安装了两个惯性测量单元（IMU）。两名健康成年人进行了平地行走，包括正常步态和再现划圈步态特征的步态，划圈步态通常在中风后偏瘫患者中观察到。开发了一种定制的步态起搏器来复制偏瘫步态的时空不对称性。使用计算负荷低的马德威克滤波器在微控制器上进行矢状面和额状面的姿势估计，并记录处理时间。通过使用均方根误差（RMSE）和互相关分析将结果与光学运动捕捉数据进行比较来评估估计准确性。
包括采样、姿势估计和刺激控制在内的平均总处理时间为 6.8 毫秒。在所有情况下，矢状面姿势角度的 RMSE 均小于 4°，表明估计准确性与先前研究相当。对于额状面姿势角度，在再现的划圈步态期间估计准确性相对较高，表明该系统有效地捕捉到了划圈运动。相反，在正常步态期间准确性往往较低。
与先前研究相比，本研究中使用马德威克滤波器的姿势估计方法能够在不影响准确性的情况下估计姿势。包括采样、姿势估计和刺激控制在内的整个过程在 10 毫秒内完成，反映了以 100 赫兹进行实时处理的可行性。
