Pneumatic pressure output control by drive valve duty cycle calibration

A method of calibrating a surgical pneumatic system, comprising:

• operating a pneumatic system comprising a pneumatic valve configured to cycle between an open position and a closed position wherein pressurized gas is directed at a first port when the valve is in the open position and wherein pressurized gas is directed at a second port when the valve is in the closed position;
• measuring pressures output by the pneumatic valve, wherein the measured pressure data comprises an open differential pressure corresponding to a differential pressure between the first port and the second port during the open position and a closed differential pressure corresponding to a differential pressure between the first port and the second port during the closed position;
• and
• calculating the valve duty cycle by:
• (a) analyzing operating pressure data for open and closed valve positions, and
• (b) determining a valve duty cycle to provide the valve open time and valve close time that will result in open and closed operating differential pressures above a predetermined threshold;
• wherein determining the valve duty cycle comprises determining a new valve duty cycle about equal to a previous valve duty cycle+((((absolute value of open pressure)−(absolute value of closed pressure))/2) times (valve duty cycle delta/differential pressure change delta)) where the previous valve duty cycle is the valve duty cycle during testing, open pressure and closed pressure are differential pressures for the port for one cycle of the valve, and wherein the valve duty cycle delta/differential pressure change delta is a ratio of valve duty cycle change to resulting differential pressure change.

A method of calibrating a surgical pneumatic system, comprising:

• operating a pneumatic system comprising a pneumatic valve configured to cycle between an open position and a closed position wherein pressurized gas is directed at a first port when the valve is in the open position and wherein pressurized gas is directed at a second port when the valve is in the closed position;
• measuring pressures output by the pneumatic valve, wherein the measured pressure data comprises an open differential pressure corresponding to a differential pressure between the first port and the second port during the open position and a closed differential pressure corresponding to a differential pressure between the first port and the second port during the closed position;
• and
• calculating a new valve duty cycle, wherein the new valve duty cycle is about equal to a previous valve duty cycle+((((absolute value of open pressure)−(absolute value of closed pressure))/2) times (valve duty cycle delta/pressure differential change delta)) where the previous valve duty cycle is the valve duty cycle during operation of the pneumatic system while measuring the pressures, open pressure and closed pressure are the measured differential pressures for the port during a corresponding open position and closed position of one cycle of the valve, and wherein the valve duty cycle delta/pressure differential change delta is a ratio of valve duty cycle change to resulting differential pressure change.