In geomagnetic navigation application

it is unavoidable that the geomagnetic vector measurement is disturbed by the magnetic field of vehicle

which will decrease the navigation accuracy.The magnetic field of vehicle must be compensated rapidly to implement the high accuracy geomagnetic navigation.The measurement errors of the strapdown magnetic sensor are analyzed and modeled firstly.Then a novel magnetic compensation method is presented.The method translates magnetic compensation into ellipse fitting in essential.The proposed method adopts the least square algorithm under ellipse restriction

rather than common iterative algorithms

for fitting an ellipse to the scattered or noisy measured data

and implements the rapid compensation of the magnetic field of vehicle.Several sets of experiments have been carried out to assess the method validity.The results indicate the proposed method is a simple

stable and robust magnetic compensation method which can be easily implemented.