Gas Proportional Mixing Module Based on Parallel Active Disturbance Rejection Control for Mechanical Ventilation

The precise mixing control of compressed air and oxygen is the key to mechanical ventilation. The existing air oxygen mixing control structure has defects such as large volume, redundant components, and poor mixing control effect, which cannot meet the requirements of miniaturization, modularization, low cost, and high precision of medical devices. Therefore, this article proposes a gas mixing control module suitable for mechanical ventilation. In order to achieve air oxygen mixing control in pressure and flow control, a dual closed-loop controller based on active disturbance rejection control (ADRC) is proposed. The feasibility of the module and controller was verified through simulation experiments. The performance of the module was tested through experiments. The module can achieve air-oxygen mixing control while controlling pressure and flow. The changes in the mixing ratio have little impact on the control effect, and the response time, overshoot, and accuracy are within <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$300 ~\text{ms}, 3 {\%}$</tex>, and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\pm 2.5 {\%}$</tex>, respectively.