Attitude control of a small satellite with uncertainly dynamic model using fuzzy logic strategy

The present paper deals with the multi-axis attitude maneuver of a small satellite with variable inertia matrix, using fuzzy logic strategy. The controller has been realized by means of a Multi Input Multi Output (MIMO) fuzzy controller with a knowledge base composed by 75 logic rules (25 logic rules for per axis). The input-domains are partitioned with 5 membership functions, resulting in 25 fuzzy rules for each rule-base. The output-domains are partitioned with 7 membership functions. The Mamdani controllers use a standard max-min inference process and a fast center of area method to calculate the crisp control signals. The satellite control is obtained autonomously by the fuzzy controller generating commands to the hybrid actuators. The actuator set combined from magnetorquers and reaction wheel to facilitate three axes maneuver. Using hybrid actuators solve the singularity problem that often occurs in active magnetic control methods. IGRF2000 was used as earth magnetic field simulation. Effects of the environmental disturbances during Attitude maneuver of the SC have been considered by developing a disturbance torques simulator module. The main features of the proposed control strategy are: simplicity in spacecraft control system design and development, increased robustness for automatic control reconfiguration and model uncertainty, reduction in development and production cost for flight control systems, autonomous on-board control features. Numerical simulations show the capabilities of the proposed approaches compared to the other classical methods (PD) such as quaternion feedback and Euler Angles feedback control laws.