Spacecraft Attitude Determination with Sun Sensors, Horizon Sensors and Gyros: Comparison of Steady-State Kalman Filter and Extended Kalman Filter

Attitude determination, along with attitude control, is critical to functioning of every space mission. In this paper, we investigate and compare, through simulation, the application of two autonomous sequential attitude estimation algorithms, adopted from the literature, for attitude determination using attitude sensors (sun sensor and horizon sensors) and rate-integrating gyros. The two algorithms include a direction cosine matrix (DCM) based steady-state Kalman Filter and the classic quaternion-based Extended Kalman Filter. To make the analysis realistic, as well as to improve the design of the attitude determination algorithms, detailed sensor measurement models are developed. Modifications in the attitude determination algorithms, through estimation of additional states, to account for sensor biases and misalignments have been presented. A modular six degree-of-freedom closed-loop simulation, developed in house, is used to observe and compare the performances of the attitude determination algorithms.