Attitude and Rate Estimation of a Spacecraft by Using Magnetometers

Abstract

New attitude and attitude rate estimation algorithms are presented for a spacecraft using magnetometers. An attitude rate estimation algorithm solves an optimization problem to identify the unknown angular rate from the short period observations of the earth magnetic field vectors, and then, estimates the angular velocity vector of the spacecraft. An attitude estimation algorithm solves another optimization problem to identify the unknown angle from the long period observation of the earth magnetic field vector and the estimated attitude rate, and then, estimates the spacecraft attitude in terms of Euler parameters. The effectiveness of the proposed algorithms is evaluated by numerical simulations. Euler parameters are a unit quaternion and three dimensional vector is a quaternion whose scalar part is 0. When the superscript B (or I) is attached to a vector, the vector is represented in the body frame (or in the inertial frame).