SMARTPHONE-BASED INERTIAL ODOMETRY

A computer implemented system useful for determining turns in a user's trajectory, including one or more processors; one or more memories; and one or more programs stored in the one or more memories, wherein the one or more programs executed by the one or more processors (1) receive input data, comprising orientation data and acceleration from one or more sensors carried by a user taking steps along a trajectory; (2) analyze the input data using a first trained machine learning algorithm so as to detect a plurality of n straight sections when the user is walking along an approximately straight path; (3) comprise an orientation tracker tracking an orientation of the user in each of the n straight sections, wherein the orientation comprises an estimated orientation taking into account drift of the input data outputted from the one or more sensors; and (4) comprise a turn detector detecting each of the turns, wherein each of the turns is a change in the estimated orientation of the user in the nstraight section as compared to the estimated orientation in the (n−1)straight section.