Systems and methods are provided for tracking a moving person. The system comprises a controller configured to receive acceleration data that characterizes an acceleration of the moving person in three dimensions. The controller comprises a step rate component that determines a step rate for the person based on a vertical component of the acceleration data. The controller also comprises a body offset component that determines a body offset angle based on a spectral analysis of the acceleration data and the step rate. The controller further comprises a velocity component that determines a reference velocity vector based on the body offset angle and the step rate.