Advanced Hybrid Control Approach for Accurate Re-Entry of Crewed Spacecraft

Abstract

In this research, a novel methodology is introduced for managing an Assured Crew Re-entry Vehicle (ACRV) characterized by a reduced lift-to-drag ratio. The proposed approach involves the utilization of a hybrid controller (HC), which is fine-tuned through the application of Simulated Annealing (SA). The primary objective is to achieve precise control over the ACRV, ensuring a close alignment between the control signal and its equivalent control, all while maintaining the system's state in proximity to a predefined reference altitude. To attain this objective, a trajectory controller is engaged to steer the vehicle along a predetermined path. The reference altitude is generated jointly by the trajectory controller and the navigation system. The HC is meticulously engineered to address potential sources of uncertainty within the system, including variations in parameters and external disturbances. To enhance the robustness of the control strategy, the inherent resilience of a Sliding Mode Controller (SMC) to disturbances is harnessed. Furthermore, the gain parameters for PID control are systematically computed and optimized to enhance their performance. The controller takes into account environmental turbulence and structural parametric uncertainties, ensuring the provision of reliable feedback control. To assess the system's sensitivity, an array of thrust torque profiles is deployed, which provides valuable insights into the controller's performance across various scenarios. Additionally, robustness analysis is conducted by introducing changes in the inertia matrix, allowing for an examination of the system's response and adaptability to fluctuations in parameters. The modulation of thrust torque by the altitude controller is achieved via a Pulse Width Pulse Frequency (PWPF) modulator, affording precise control over the motion of the ACRV. Through an extensive series of simulation studies, the proposed approach is consistently found to meet various criteria and requirements, unequivocally demonstrating its efficacy in realizing the desired control objectives for the ACRV.