UAV Altitude Measurement at Extremely Low Flight Paths

Abstract

The predicted intensive use of UAVs in urban area projects need measurements of the extermely low  flight altitudes of the UAVs in the range of metres. This article deals with those measurement techniques that are applicable aboard on UAVs with  small sizes, small weights and low level 
of electrical energy consumption. The ultrasonic range finders will be discussed, and the old fashioned method based on Earth capacitance measurement will be subjected to review. Relying on these techniques, the UAV height control system and also the UAV terrain-following system can be designed.