Effort-Efficient Attitude Control of Satellites Using PD and Nonlinear MPC

Advanced and effective attitude determination and control techniques have become increasingly essential due to the growing importance of the space industry, especially in satellite missions. Satellite attitude control ensures precise orientation, which is critical to mission success across a wide range of applications. In this study, a nonlinear satellite attitude model is developed using a quaternion-based formulation, and a reaction wheel assembly is selected as the actuator to generate the required control torque. To achieve the desired orientation, two controllers are employed: a conventional Proportional-Derivative (PD) controller and a Nonlinear Model Predictive Controller (NMPC), the latter designed to minimize control effort over a finite prediction horizon by optimizing control variables through a system model. The PD controller is tuned specifically to reduce control effort, while NMPC aims for near-optimal performance under constraints. The proposed control strategies are evaluated under various orientation scenarios across all three axes (roll, pitch, and yaw). Simulation results demonstrate that the NMPC achieves significantly lower control effort compared to the PD controller—reducing effort by 29%, 24%, and 33% in roll, pitch, and yaw maneuvers, respectively.