HIGH-ACCURACY NAVIGATION AND LANDING SYSTEM USING GPS IMU SYSTEM INTEGRATION

In this paper, the accuracy, integrity and continuity of function requirements for automatic landing systems using Satellite Navigation Systems will be discussed. Such a landing system is the Integrated Navigation & Landing System (INLS) developed by Deutsche Aerospace (DASA/Ulm, Germany). The system concept of the INLS will be presented. It will be shown how an INLS, based on system integration of a Satellite Navigation System (e.g., GPS) in Realtime Differential Mode with an Inertial Measurement Unit (IMU) in the accuracy class of an Attitude and Heading Reference System (AHRS), can meet the requirements: the results given in this paper are mainly devoted to the accuracy issues. Using Kalman Filter techniques, an in-flight calibration of the Inertial Measurement Unit is performed. The advantage of system integration, especially in dynamic flight conditions and during phases of flight with satellite masking, will be explained. The accuracy, integrity and continuity of function of the INLS were proven by means of flight tests in a commuter aircraft using a Laser Tracker as a reference. These flight tests have shown that the short-term accuracy (< 60 seconds) of the AHRS used within the INLS has been improved from low cost sensor quality to the accuracy of a high quality Laser Inertial Navigation System (LNIS). With the presented INLS, a landing at any airfield, not equipped with conventional Instrument Landing System (ILS) or Microwave Landing System (MLS), will be possible by using a very cost effective system. Even curved approaches can be realized. Also holding patterns with recurring satellite masking can be flown without significant accuracy degradation. The INLS is a high accuracy navigation and landing system designed to be used instead of conventional landing systems at small airfields and to fill operational gaps of conventional navigation and landing systems in cruise and approach on large airports.