Time domain validation of a fractional order model for human respiratory system

This contribution presents a validation in time domain of a non-integer-order parametric model of the input respiratory impedance. Non-invasive measurements of the air-flow and air-pressure from both healthy and pathologic subject groups are performed and complex impedance by means of its real and imaginary parts is estimated between 4-48 Hz using nonparametric techniques (spectral analysis). Further on, nonlinear identification provides the fractional-order model parameters and a frequency-band non-integer differentiator synthesis procedure is employed to approximate a higher integer order transfer function. This then allows a time-domain simulation and validation to measured signals from subjects at the 5 Hz frequency of a ventilatory assisting device. The final aim of the investigation is to compare classical integer-order control with fractional order control techniques in a ventilatory assisting device.