There is growing interest in using inertial sensors to continuously monitor gait during free-living mobility. Inertial sensors can provide many gait measures, but they struggle to capture the spatial stability of the center-of-mass due to limitations estimating sensor-to-sensor distance. While the margin of stability (MoS) is an established outcome describing the instantaneous mechanical stability of gait relating to fall-risk, methods to estimate the MoS from inertial sensors have been lacking. Here, we developed and tested a framework, based on centripetal acceleration, to determine a correlate for the lateral MoS using inertial sensors during walking with or without turning. Using three synchronized sensors located bilaterally on the feet and lumbar spine, the average centripetal acceleration over the subsequent step can be used as a correlate for lateral MoS. Relying only on a single sensor on the lumbar spine yielded similar results if the stance foot can be determined from other means. Additionally, the centripetal acceleration correlate of lateral MoS demonstrates clear differences between walking and turning, inside and outside turning limbs, and speed. While limitations and assumptions need to be considered when implemented in practice, this method presents a novel correlate for the lateral MoS during walking and turning using inertial sensors, although further validation is required for other activities and populations.

中文翻译：

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基于惯性传感器的向心加速度与步行和转弯时的侧向稳定性相关。

人们在使用惯性传感器来连续监控自由活动的步态时越来越感兴趣。惯性传感器可以提供许多步态测量方法，但是由于估计传感器到传感器的距离受到限制，它们难以捕捉质量中心的空间稳定性。尽管稳定性裕度（MoS）是描述与跌落风险相关的步态的瞬时机械稳定性的既定结果，但仍缺乏从惯性传感器估算MoS的方法。在这里，我们开发并测试了基于向心加速度的框架，以确定在有或没有转弯的步行过程中使用惯性传感器确定横向MoS的相关性。使用三个同步传感器，分别位于脚和腰椎两侧，后续步骤的平均向心加速度可用作横向MoS的相关系数。如果可以通过其他方法确定脚的姿势，则仅依靠腰椎上的单个传感器即可得到相似的结果。此外，外侧MoS的向心加速度相关性表明行走和转弯，内外转弯肢体和速度之间存在明显差异。尽管在实践中需要考虑局限性和假设条件，但此方法为使用惯性传感器的行走和转弯过程中的横向MoS提供了一种新颖的关联性，尽管其他活动和人群也需要进一步验证。侧向MoS的向心加速度相关性表明行走与转弯，内侧和外侧转弯肢体以及速度之间存在明显差异。尽管在实践中需要考虑局限性和假设条件，但此方法为使用惯性传感器的行走和转弯过程中的横向MoS提供了一种新颖的关联性，尽管其他活动和人群也需要进一步验证。侧向MoS的向心加速度相关性表明行走与转弯，内侧和外侧转弯肢体以及速度之间存在明显差异。尽管在实践中需要考虑局限性和假设条件，但此方法为使用惯性传感器的行走和转弯过程中的横向MoS提供了一种新颖的关联性，尽管其他活动和人群也需要进一步验证。