Janschek: “Optical flow navigation for an outdoor UAV using a wide angle mono camera and DEM

Visual navigation for low altitude unmanned aerial vehicles (UAV) shows many scientific and technical challenges in terms of navigation performances, complex 3D environment, high computational requirements for real-time image processing and very limited onboard mass and power resources. The current paper presents a concept of a visual navigation system, based on a wide angle mono camera as vision sensor and matching of the recovered and reference 3D environment, modeled by a digital elevation map (DEM). The recovered 3D models are being produced by real-time optical flow processing of the navigation camera images. An embedded optical correlator is introduced, which allows a robust and ultra high-speed optical flow processing under different and even unfavorable illumination conditions. The proposed concept can be augmented by any state-of-the art navigation aids, e.g. GPS, IMU, magnetometers. The current paper discusses the general principles and structure of the navigation system as a vision only system, i.e. without any additional navigation aids, and with instantaneous determination of the vehicle state, i.e. without time filtering. The paper gives also detailed end-to-end visual navigation performance results, based on a detailed software simulation model of the visual navigation system, including the optical correlator as the key component for ultra-high speed image processing. Copyright © 2002 IFA