Optimal Hybrid Attitude Control of Spacecraft in Elliptical Orbit

During the spacecraft attitude control, pure magnetic control suffers from under actuation and limited torque authority, restricting its effectiveness, particularly in elliptical orbits where the magnetic field does not vary as regularly as it does in circular orbits. This paper explores the integration of an impulse thruster alongside a magnetic torque generator, employing a combination of continuous and discrete control moments to enhance attitude maneuverability and stability. By leveraging the complementary characteristics of both control methods, a more effective attitude control strategy can be achieved. Based on this hybrid torque application, a Linear Quadratic Regulator (LQR)-based attitude control strategy is developed for spacecraft operating in elliptical orbits. The proposed control framework dynamically determines the timing and magnitude of discrete impulses to compensate for the deficiencies of pure magnetic control. By analyzing the relationship between magnetic control effectiveness and variations in the eccentricity of elliptical orbit, we identify the point at which pure magnetic control exhibits its weakest capability. At this critical moment, an appropriately impulse is applied, compensating for the system’s required control gain through discrete thrust pulses. This method ensures that the spacecraft maintains the desired attitude control effects with improved accuracy and robustness. Furthermore, the proposed hybrid control approach is evaluated through numerical simulations under given orbital and disturbance conditions. Simulation results demonstrate that the proposed hybrid LQR control method significantly enhances attitude control performance compared to purely magnetic control strategies. The introduction of pulse thrusters effectively reduces the regulation time and improves the transient performance of the system. These findings highlight the effectiveness of the hybrid control approach in addressing the challenges of spacecraft attitude regulation in elliptical orbits and provide valuable insights into advanced control methodologies for spacecraft operating.