Integration of Hybrid Active Disturbance Rejection with Sliding Mode Control for Robust Mechanical Ventilation

This study addresses the challenge of precise control within the human respiratory system, a complex, nonlinear, and time-varying physiological process. The research contribution is to develop and evaluate a robust hybrid controller that integrates Active Disturbance Rejection Control (ADRC) with Sliding Mode Control (SMC) to overcome the limitations of traditional control methods. The respiratory system's behavior is modeled as a state-space system, where internal and external disturbances, such as changes in lung mechanics, patient effort, and environmental factors, can significantly impact performance. We conducted a series of simulations to validate the effectiveness of the proposed controller. The hybrid ADRC-SMC controller was rigorously compared with ADRC using a nonlinear PD controller (ADRC-NPD) across various simulated scenarios. The results demonstrate that the ADRC-SMC responds better than the ADRC-NPD. The ADRC-SMC achieved a settling time of 0.3 seconds, a rise time of 0.1 seconds, and a tracking efficiency exceeding 98%, outperforming the ADRC-NPD. While traditional SMC often suffers from chattering, the ADRC component effectively mitigates this issue by estimating and compensating for disturbances, resulting in smoother control signals and reduced torque ripple. The advanced ADRC-SMC controller effectively regulates the respiratory system, offering superior performance and robustness against disturbances. The key limitation is the inherent computational complexity of the ADRC algorithm, which may pose challenges for real-time implementation on low-power hardware. While the hybrid approach reduced chattering, a small degree of control effort oscillation remains, warranting further investigation into advanced techniques for reducing chattering. Future work will optimize the algorithm's efficiency and expand its clinical applications for greater generalizability.