The Motek CAREN and GRAIL systems are equipped with an instrumented treadmill mounted on a moveable platform. This setup goes beyond standard clinical gait analysis and allows the assessment of gait in more challenging conditions, such as balance perturbations and up and down hill walking. However, such platform movements induce large errors in force measurements due to inertial and gravitational artifacts. Therefore, all parameters derived from the force measurements, such as joint moments, can only be used with the platform in neutral position. This paper introduces a simple accelerometer-based method to compensate for such errors. First, a model is created of the inertial artifacts by collecting accelerometer and force plate data during random movements of the unloaded system. This model is then used to predict and subtract the inertial artifacts from the force measurements during the actual data collection. The authors conclude that the proposed compensation method reduces the errors to acceptable levels for human gait analysis (<2Nm).
Check out the full article here: Hnat S.K et al (2018) Journal of Biomechanics
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