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

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 is concentrating 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 when pilots cannot evaluate visually the horizontal movement many accidents happen. 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 (which may happen e.g. 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, 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 recorded from flight tests that have been conducted with DLR’s flying helicopter simulator EC135 (ACT/FHS)