ALLFlight - Blob-Based Approach to Detect Dangerous Drift- Velocities during Helicopter Landing Approaches

Kurzfassung

The Institute of Flight Systems at the German Aerospace Center (DLR) site in Braunschweig is dedicating much effort to the goal of making helicopter flying safe. This paper concentrates on decreasing the danger of accidents caused by so-called “dynamic rollovers” which may result from undetected lateral velocities during the landing approach. Especially in degraded visual environment situations where pilots cannot visually evaluate the horizontal movement, accidents are likely to occur. While under normal circumstances the combination of INS and GPS is usually sufficient to detect critical lateral drift velocities, during the landing process, the INS drift may reach a dangerously high value quite soon after the GPS signal has been lost (for instance, in canyons, cities, or due to jamming). The vision algorithm that is proposed here uses a blob-based approach to solve this problem. Blobs are regions in an image that fit together bound by a specific criterion. In this paper, we will describe how an image is segmented, possible blobs are selected and characterized, how they are tracked, and how the velocity of the helicopter is calculated. Finally, the accuracy of this algorithm will be analyzed using data that have been recorded from flight tests conducted by the DLR’s flying helicopter simulator EC135 (ACT/FHS).