This paper addresses the onboard prediction of a motor vehicle's path to he
lp enable a variety of emerging functions in autonomous vehicle control and
active safety systems. It is shown in simulation that good accuracy of pat
h prediction is achieved using numerical integration of a linearized two de
gree of freedom vehicle handling model. To improve performance, a steady-st
ate Kalman filter is developed to estimate the vehicle's lateral velocity a
nd the magnitudes of external disturbances acting on the vehicle, specifica
lly the lateral force and the yaw moment disturbances. A comparison is made
between three models of external disturbance time variation; a piecewise-c
onstant-in-time model is found to be sufficient. Finally, an algorithm is p
roposed to characterize path prediction uncertainty using a statistical cha
racterization of the measurement and modeling errors. Simulation suggests t
hat these algorithms may provide a useful suite of path prediction tools fo
r a variety of applications.