STEPPING MOTOR CONTROL PROCEDURE FOR ACHIEVING VARIABLE RATE, QUASI-CONTINUOUS FLUID INFUSION

摘要

STEPPING MOTOR CONTROL PROCEDURE FORVARIABLE RATE, QUASI-CONTINUOUSINTRAVENOUS ADMINISTRATIONAbstractA control procedure for governing the incremental stepoperation of a pump stepping motor (74) employed in conjunctionwith a parenteral fluid metering device (2) is disclosed. Thecontrol procedure enables fluid to be pumped from the meteringdevice (2) in non-pulsatile, essentially continuous fashionby suitably adjusting the stepping motor speed to compensatefor the interruption of fluid flow which occurs during therefill phase (Pr) of each pumping cycle (C). Adjustment ofthe stepping motor speed also compensates for non-linearitiesotherwise introduced into the fluid flow as a result of thecamming mechanism (76,78) utilized to convert rotary steppingmotor movement into rectilinear pumping movement. Operatingpower for the stepping motor is conserved by drawing rela-tively large amounts of current through the stepping motor(74) only at the outset of each incremental step while drawingrelatively smaller amounts of current through the steppingmotor (74) during the remaining interval between incrementalsteps.