A method of motion parameter estimation for AGV’s is developed based on a new trajectory constraint algorithm. It is assumed that the vehicle will follow a circular path over the vision sampling interval. The algorithm has been found to be more effective and consistent than least squares estimators when the motion obeys the trajectory constraint. Reliable estimates of the motion parameters can even be made from individual data pairs. In this way, a static world can be segmented from moving objects, and so the motion parameters can be obtained using the stationary points alone.