Attitude stabilization of a nadir-pointing small satellite using only magnetic actuators

Recently, there has been a surge of interest in small satellite missions due to low-cost launch opportunities. In particular, the feasibility of nonlinear techniques for the attitude control of small satellites using only magnetic actuators is becoming a topic of increasing interest in the literature. Since magnetic control systems are relatively lightweight, require low power and are inexpensive, they are attractive for small, inexpensive satellites in low Earth orbits. In this paper we present averaging-based feedback control laws that achieve three-axis stabilized nadir-pointing attitude. We propose nonlinear quaternion feedback laws. Two cases are considered; full state feedback that uses both attitude and angular velocity measurement and passivity-based feedback that does not require angular velocity information. Computer simulations are included to illustrate the effectiveness of the proposed control laws.