Comparison of different motion capture setups for Gait Analysis : Validation of spatio-temporal parameters estimation

Inertial measurement units (IMUs) are increasingly used in gait analysis because of their portability, low cost and long-distance measuring. The aim of this study focused on the comparison of 2 different inertial sensors setups and algorithms respect to a reference measure system for the estimation of gait spatio-temporal parameters. (a) A marker stereo photogrammetric system (Optitrack) was used as reference goldstandard. Two IMU setups were adopted for the comparison of different algorithms: (b) a single sensor positioned on the trunk, and (c) 2 sensors positioned on the heels. Three healthy subjects performed gait trials at 3 different self-selected speeds: (α) normal, (β) slower than normal, (γ) higher than normal. Data analysis considered signals that had been registered simultaneously by the three setup instrumentations. Among the IMUs signals, acceleration and angular velocity were considered and used for gait parameters estimation. Signal post-processing was performed through algorithms analyzing signals with respect to the local sensor axes, avoiding cumbersome pre-processing. The absolute errors among the spatio-temporal gait parameters obtained by the 3 setups were evaluated. Overall, IMUs allowed an accurate parameters estimation, at all the performed velocities. A consistent correspondence was confirmed by the comparison of estimated spatio-temporal parameters. However, for most of them, the trunk configuration revealed smaller errors with respect to the heels configuration. This may be explained by a better identification of gait events guaranteed by the trunk IMU algorithm. The results demonstrated the suitability and accuracy of the trunk IMU setup and algorithm for the estimation of spatio-temporal parameters during gait. Besides, the trunk IMU setup requires the use of only one sensor instead of two.