Patent attributes
A terrain-based navigation system include at least three laser range finders, each fixedly mounted to a vehicle body, each pointing in a different direction and arranged such that they can be used to calculate terrain gradient in two dimensions. Existing terrain-based navigation systems for aircraft that use a radar altimeter to determine the distance of the vehicle from the ground make use of the large field of view of the radar altimeter. The first return signal from the radar altimeter may not be from directly below the aircraft, but will be interpreted as being directly below the aircraft, thereby impairing the chances of obtaining a terrain match, or impairing the accuracy of a terrain match. The use of a plurality of laser range finders each fixedly mounted to the vehicle body allows more terrain information to be obtained as the terrain can be detected from the plurality of different directions.
