Validation of Inertial Sensors to Evaluate Gait Stability

Abstract

The portability of wearable inertial sensors makes them particularly suitable for measuring gait in real-world walking situations. However, it is unclear how well inertial sensors can measure and evaluate gait stability compared to traditional laboratory-based optical motion capture. This study investigated whether an inertial sensor-based motion-capture suit could accurately assess gait stability. Healthy adult participants were asked to walk normally, with eyes closed, with approximately twice their normal step width, and in tandem. Their motion was simultaneously measured by inertial measurement units (IMU) and optical motion capture (Optical). Gait stability was assessed by calculating the margin of stability (MoS), short-term Lyapunov exponents, and step variability, along with basic gait parameters, using each system. We found that IMUs were able to detect the same differences among conditions as Optical for all but one of the measures. Bland–Altman and intraclass correlation (ICC) analysis demonstrated that mediolateral parameters (step width and mediolateral MoS) were measured less accurately by IMUs compared to their anterior-posterior equivalents (step length and anterior-posterior MoS). Our results demonstrate that IMUs can be used to evaluate gait stability through detecting changes in stability-related measures, but that the magnitudes of these measures might not be accurate or reliable, especially in the mediolateral direction.

Estimating the Margin of Gait Stability in Healthy Elderly Using the Triaxial Kinematic Motion of a Single Body Feature

“…When attaching the IMUs to these points using a cloth bandage, areas near joints where the attachment may loosen during extended periods of walking should be avoided. In practice, IMUs are typically affixed near the knee, either on the femoral or tibial parts [10,[51][52][53]. Considering these practical considerations for fixation, further research is needed to refine our understanding and approach.…”

“…A common objective of these indices is to facilitate the identification of such individuals, enabling the provision of appropriate interventions to mitigate fall risks [3]. In the pursuit of accessible measures for assessing fall risks, the potential of inertial measurement units (IMUs) for gait analysis has garnered significant interest [4][5][6][7][8][9][10]. For instance, Kim et al [4] employed an IMU sensor embedded in a shoe to calculate basic gait parameters such as stride and walking speed.…”

“…The computation of the MoS necessitates the simultaneous measurement of multiple body points, typically requiring an optical or IMU-based [10] motion capture system, limiting MoS recordings to laboratory settings. However, if the MoS is estimated, using devices such as IMUs embedded in smartphones, this can increase awareness among people about their gait instability and falling risk.…”

Modified stepping behaviour during outdoor winter walking increases resistance to forward losses of stability

“…Additionally, the equipment used in the data collection, IMU-based motion capture and instrumented insoles, are known to be less accurate than their traditional counterparts, optical motion capture and in-ground force plates 22 , 34 . One of our previous studies compared stability measures derived from the IMU suit and optical motion capture 38 . We found that although the accuracy of the IMU system may be reduced, they are still sensitive to changes in behaviour, allowing for meaningful insights to be gained.…”

Changes in Seasonal Footwear Elicited Alterations in Gait Kinematics but Not Stability

“…We found no changes with the MoS and LDE stability measures, but it is possible that other stability measures might yield significant changes. Although wider step widths was the only significant stability-related change, inertial sensors cannot directly measure distance between each other, and estimates of step width may be less accurate than other spatiotemporal estimates [17,18,19]. In addition, the number of strides available for the LDE analysis was 109 strides, and more strides could lead to more precise estimates of λ s [20].…”