Estimation of displacement along level straight paths through body center of mass accelerations

User localization is crucial for the development of context aware applications for intelligent environments. Wearable systems based on accelerometry have been proposed in recent years to palliate the drawbacks posed by infrastructure based approaches. In this paper, we address the estimation of the displacement length of a user when walking straight ahead along flat surfaces by directly processing the raw accelerations from the body center of gravity. We analyze and compare two approaches from the state of the art. The effect of gender and excursion velocity on the performance of the estimators are especially addressed.