Robust Feedback Design for Proportional Assist Ventilation-System Dynamics and Problem Definition

Robust control analysis and design of feedback controllers for life support medical ventilators are discussed in the context of Proportional Assist Ventilation. Controllers for critical care ventilators are required to have robust performance in the presence of time-varying global dynamic uncertainty. Proportional Assist Ventilation (PAV) is intended to detect, estimate, and track patient´s spontaneous breathing effort and provide timely ventilatory support with specified air and O2gas mix. The main design consideration for a PAV controller is the non-deterministic, time-variant, and patient-dependent nature of the reference tracking trajectory. The controller´s reference is determined quasi-real time based on estimated lung model parameters, predicted spontaneous breathing effort, and percent support set by clinician. In this paper, we discuss system dynamics, define the control design problem, and briefly comment on well posedness, internal stability, and controller synthesis.