ROBUST CONTROL OF END-TIDAL CO 2 USING THE H ∞ LOOP-SHAPING APPROACH

摘要

Mechanically ventilated patients require appropriate settings of respiratory control variables to maintain acceptable gas exchange. To control the carbon dioxide (CO 2 ) level effectively and automatically, system identification based on a human subject was performed using a linear affine model and a nonlinear Hammerstein structure. Subsequently, a robust controller was designed using the H ∞ loop-shaping approach, which synthesizes the optimal controller based on a specific objective by achieving stability with guaranteed performance. For demonstration purposes, the closed-loop control ventilation system was successfully tested in a human volunteer. The experimental results indicate that the blood CO 2 level may indeed be controlled noninvasively by measuring end-tidal CO 2 from expired air. Keeping the limited amount of experimental data in mind, we conclude that H ∞ loop-shaping may be a promising technique for control of mechanical ventilation in patients with respiratory insufficiency.