Validation of a Magnetic Anomaly Navigation Model with Flight Test Data

Abstract

GPS-alternative navigation technologies are an active research area. Many current GPS-alternative navigation systems share common limitations such as where and when the systems can operate. For example, vision aided navigation systems perform poorly over featureless oceans, and star tracker systems are limited by thick cloud cover. Magnetic anomaly navigation shows potential to achieve the world-wide, continuous coverage which GPS provides. This paper presents a magnetic anomaly navigation model which is validated using previously obtained flight test data. This model allows the prediction of magnetic anomaly navigation accuracy over any location in which a magnetic anomaly map is available. The major variables which effect navigation accuracy are the altitude of the flight, the quality of the magnetic anomaly map, the quality of the inertial navigation system, and the spatial variability of the magnetic field over a given location. Minor variables which affect navigation accuracy are space weather effects and the specific flight path chosen. We compare the predicted performance from the magnetic anomaly navigation model with the actual performance from two separate flight tests to validate the accuracy of the model. The first flight test scenario demonstrates navigation performance under ideal conditions – at low altitudes with a high quality map. The second flight test scenario shows performance at higher altitudes with a high quality map. In each flight test scenario the predicted performance from the model matches the actual performance when using real data. Finally, we use the validated model to present predictions of magnetic anomaly navigation performance over the United States with respect to location, altitude, and velocity.