Tietsch Matthias, Muaremi Amir, Clay Ieuan, Kluge Felix, Hoefling Holger, Ullrich Martin, Küderle Arne, Eskofier Bjoern M, Müller Arne
Novartis Institutes of Biomedical Research, Novartis Pharma AG, Basel, Switzerland.
Machine Learning and Data Analytics Lab, Department of Computer Science, Friedrich-Alexander University Erlangen-Nürnberg, Nürnberg, Germany.
Digit Biomark. 2020 Nov 26;4(Suppl 1):50-58. doi: 10.1159/000511611. eCollection 2020 Winter.
Analyzing human gait with inertial sensors provides valuable insights into a wide range of health impairments, including many musculoskeletal and neurological diseases. A representative and reliable assessment of gait requires continuous monitoring over long periods and ideally takes place in the subjects' habitual environment (real-world). An inconsistent sensor wearing position can affect gait characterization and influence clinical study results, thus clinical study protocols are typically highly proscriptive, instructing all participants to wear the sensor in a uniform manner. This restrictive approach improves data quality but reduces overall adherence. In this work, we analyze the impact of altering the sensor wearing position around the waist on sensor signal and step detection. We demonstrate that an asymmetrically worn sensor leads to additional odd-harmonic frequency components in the frequency spectrum. We propose a robust solution for step detection based on autocorrelation to overcome sensor position variation (sensitivity = 0.99, precision = 0.99). The proposed solution reduces the impact of inconsistent sensor positioning on gait characterization in clinical studies, thus providing more flexibility to protocol implementation and more freedom to participants to wear the sensor in the position most comfortable to them. This work is a first step towards truly position-agnostic gait assessment in clinical settings.
使用惯性传感器分析人类步态能为包括许多肌肉骨骼和神经疾病在内的广泛健康损伤提供有价值的见解。对步态进行具有代表性和可靠性的评估需要长时间的持续监测，理想情况下应在受试者的习惯环境（现实世界）中进行。传感器佩戴位置不一致会影响步态特征描述并影响临床研究结果，因此临床研究方案通常规定性很强，要求所有参与者以统一方式佩戴传感器。这种严格的方法提高了数据质量，但降低了总体依从性。在这项工作中，我们分析了在腰部周围改变传感器佩戴位置对传感器信号和步长检测的影响。我们证明，不对称佩戴的传感器会在频谱中导致额外的奇次谐波频率成分。我们提出了一种基于自相关的稳健步长检测解决方案，以克服传感器位置变化（灵敏度 = 0.99，精度 = 0.99）。所提出的解决方案减少了临床研究中传感器位置不一致对步态特征描述的影响，从而为方案实施提供了更大的灵活性，并给予参与者更大的自由，使其能够在最舒适的位置佩戴传感器。这项工作是迈向临床环境中真正与位置无关的步态评估的第一步。
