Fuzzy disturbance observer based attitude controller design for spacecraft

Fuzzy disturbance observer and feedback linearization method are adopted to solve the attitude control problem for the rigid spacecraft driven by three orthogonal reaction flywheels. Since the spacecraft model is nonlinear and strongly coupled, it is difficult to design the controller directly. Differential geometry theory based feedback linearization technique is used to convert the original model to the linear decoupled SISO system models, which greatly simplifies the controller design. The fuzzy disturbance observer based on fuzzy basis function vector is used to observe the disturbance torque. The estimated value of disturbance torque is converted to equivalent control by the gain adjustment part. The equivalent control along with the control obtained by feedback linearization are then used as the input to the reaction flywheels. Simulation results show that the proposed method can counteract the effect of the disturbance torque, and achieve accurate tracking of attitude.