Attitude control of pico-satellite using flywheel based on fractional order sliding mode

A quaternion based attitude model of a spacecraft that describes the three-axis stabilized pico-satellite equipped with momentum wheel considering gravity gradient torque disturbance is proposed in this paper. A linearized state space model that includes only three angle velocities and three components of the quaternion is derived from Taylor expansion and Jacobian matrix. Based on the linearized model, a fractional order sliding mode controller is designed in the light of Lyapunov stability theorem. Numerical simulations are also provided to show the proposed results and to validate the effectiveness of the new robust fractional sliding mode controller.