Reliable Feature Extraction from MMW Radar Images for Navigation during Approach and Landing

摘要

Approaches and landing maneuvers are some of the most critical tasks in aviation. Especially under adverse weather conditions (when the runway can 't be seen) pilots need additonal information to improve their situational awareness. Therefore, a new-prospering field of aircraft guidance research called Enhanced Vision Systems (EVS) has been established. Generally, EV systems consist of two main parts, sensor vision and synthetic vision. Synthetic vision usually generates a virtual out-the-window view and its accuracy and reliability depend on precise databases as well as on accurate navigation data, e. g. provided by differential GPS (DGPS) or by instrumental landing systems (ILS). The additional use of forward looking imaging sensors offers the possibility to detect unexpected obstacles, to monitor the integrity of databases and navigation data and to extract navigation information, e. g. the relative position of runway and aircraft, directly from the sensor data. The latter is very important if no ILS or DGPS is available, especially under adverse weather conditions. Up to now, the most promising EV sensor due to its lowest weather dependency compared to other imaging sensors seems to be the Hi Vision sensor from DASA Ulm, a 35 GHz MMW radar with a frame rate of about 16 Hz. For navigation purposes during approach and landing the position of runway relative to the aircraft is one of the most important information for pilots. Consequently, a robust and reliable extraction of runway structures out of radar images is a basic requirement to derive this navigation information from radar data. In this contribution we present the entire sensor data processing chain: the sensor calibration, low-level processing routines and the integration/fusion of the extracted information in/with additional knowledge. The performance of our approach is demonstrated with real data acquired during extensive flight tests to several airports in Northern Germany.