Department of Electrical and Computer Engineering, University of Alberta, Edmonton, AB, Canada T6G 2V4.
Gait Posture. 2014;39(1):485-9. doi: 10.1016/j.gaitpost.2013.08.021. Epub 2013 Aug 31.
When children walk on their toes for no known reason, the condition is called Idiopathic Toe Walking (ITW). Assessing the true severity of ITW can be difficult because children can alter their gait while under observation in clinic. The ability to monitor the foot angle during daily life outside of clinic may improve the assessment of ITW. A foot-worn, battery-powered inertial sensing device has been designed to monitor patients' foot angle during daily activities. The monitor includes a 3-axis accelerometer, 2-axis gyroscope, and a low-power microcontroller. The device is necessarily small, with limited battery capacity and processing power. Therefore a high-accuracy but low-complexity inertial sensing algorithm is needed. This paper compares several low-complexity algorithms' aptitude for foot-angle measurement: accelerometer-only measurement, finite impulse response (FIR) and infinite impulse response (IIR) complementary filtering, and a new dynamic predict-correct style algorithm developed using fuzzy c-means clustering. A total of 11 subjects each walked 20 m with the inertial sensing device fixed to one foot; 10 m with normal gait and 10 m simulating toe walking. A cross-validation scheme was used to obtain a low-bias estimate of each algorithm's angle measurement accuracy. The new predict-correct algorithm achieved the lowest angle measurement error: <5° mean error during normal and toe walking. The IIR complementary filtering algorithm achieved almost-as good accuracy with less computational complexity. These two algorithms seem to have good aptitude for the foot-angle measurement problem, and would be good candidates for use in a long-term monitoring device for toe-walking assessment.
当儿童不明原因踮脚走路时，这种情况被称为特发性踮脚行走（idiopathic toe walking，ITW）。由于儿童在诊所观察时可以改变他们的步态，因此评估 ITW 的真正严重程度可能具有挑战性。在诊所外的日常生活中监测脚部角度的能力可能会改善 ITW 的评估。已经设计了一种可穿戴的、电池供电的惯性传感设备来监测患者在日常活动中的脚部角度。该监测器包括一个三轴加速度计、一个两轴陀螺仪和一个低功耗微控制器。该设备必须小巧，电池容量和处理能力有限。因此，需要一种高精度但低复杂度的惯性传感算法。本文比较了几种低复杂度算法在脚部角度测量方面的能力：仅使用加速度计测量、有限脉冲响应（finite impulse response，FIR）和无限脉冲响应（infinite impulse response，IIR）互补滤波，以及一种使用模糊 c-均值聚类开发的新的动态预测-校正样式算法。共有 11 名受试者每人将惯性传感设备固定在一只脚上，行走 20 m；其中 10 m 采用正常步态，10 m 模拟踮脚行走。使用交叉验证方案获得了每种算法角度测量精度的低偏差估计。新的预测-校正算法在正常和踮脚行走时的角度测量误差最小：<5°平均误差。IIR 互补滤波算法具有几乎相同的准确性，但计算复杂度较低。这两种算法似乎都非常适合脚部角度测量问题，并且是用于评估踮脚行走的长期监测设备的良好候选者。
