Closed loop control system for a high frequency oscillation ventilator

A method of regulating movement of an oscillator piston of a patient ventilator using an oscillator controller comprising an oscillator pressure loop and a centering loop, the method comprising the steps of:

• in the oscillator pressure loop:
• measuring a pressure at the patient and generating a measured pressure signal representative thereof;
• filtering the measured pressure signal to limit bandwidth thereof to between a predetermined transition frequency and a noise-limiting frequency and generating a filtered pressure signal in response thereto;
• receiving a desired oscillator pressure signal;
• summing the filtered pressure signal and the desired oscillator pressure signal and generating an oscillator pressure error signal in response thereto;
• and
• filtering the oscillator pressure error signal through an oscillator pressure loop proportional integral (PIP) controller and generating a pressure output signal in response thereto;
• and
• in the centering loop:
• measuring a piston position with respect to a midpoint of full stroke of said piston and generating a piston displacement signal representative thereof;
• filtering the piston displacement signal to limit bandwidth thereof to between static and the predetermined transition frequency and generating a filtered displacement signal in response thereto;
• subtracting the filtered displacement signal from zero as a desired piston position and generating a displacement error signal in response thereto;
• filtering the displacement error signal through a centering loop proportional integral (PIX) controller and generating a displacement output signal in response thereto;
• summing the pressure and displacement output signals and generating the oscillator command signal in response thereto for driving the piston movement;
• and
• centering said piston about said midpoint of full stroke of said piston while regulating MAP.