Various embodiments are described herein for devices, methods and systems for a breathing assistance device controller for controlling the operation of a breathing assistance device that provides breathing assistance to a user. The controller may include sensors for measuring airflow parameters of the airflow and generating measured signals; and a processor that is electronically coupled to the sensors to receive the measured signals and to generate a control signal based on the measured signals and at least one characteristic of the user's respiratory system to adjust the operation of the breathing assistance device during use.