Transversal Strapdown INS Based on Reference Ellipsoid for Vehicle in the Polar Region

The transversal coordinate system has been proposed to solve the problem of navigation in the Polar Region for a strapdown inertial navigation system (INS). However, it is assumed that the Earth is a perfect sphere in the transversal coordinate system, which is not accurate for a high-precision INS. To solve this problem, we consider the Earth as a reference ellipsoid and then deduct its radii of curvature in our transversal coordinate system. In addition, with the aid of the Bessel geodetic projection method, transformations of navigation quantities from a local-level coordinate system to our transversal coordinate system are derived based on the reference ellipsoid. Numerical results indicate that our method based on the reference ellipsoid performs better than the method based on a reference sphere.