Multirate and event driven Kalman filters for helicopter passive ranging

The use of passive range estimation methods for helicopters equipped with a single camera and an inertial navigation system is described. It is shown that the same level of estimation accuracy can be maintained by using multirate and event-driven Kalman filters as with a standard Kalman filter, resulting in a substantial reduction in the amount of computation. These results are based on helicopter flight test images. The actual savings will depend on the details of the implementation