Reconstruction of spacecraft attitude motion by measurements of star trackers and angular rate sensor using least squares method

We consider the reconstruction of spacecraft attitude motion by measurements of angular rate sensor and star trackers. The processing technique uses kinematical equations of the attitude motion of a rigid body. In its framework, the measurement data of both types, collected on a time interval, are processed jointly. The angular rate data are put into kinematical equations for components of the quaternion, which defines a transformation of the coupled spacecraft coordinate system to the inertial one. The equations obtained present the model of a spacecraft attitude motion. The solution of the equations, which approximates the real motion, is found by the least squares method from the condition of the best agreement between measurement and calculation data of the magnetic strength. The technique allows reconstructing the attitude motion on time intervals up to 1000 seconds.