SYSTEM FOR DETERMINING MOTOR POSITION IN A BIOMEDICAL DEVICE

摘要

A drive member of a peristaltic pumping mechanism includes a disk (24) that rotates with the drive member (18) and has two transparent sectors (27, 26) and two opaque sectors (28, 29) alternating with the transparent sectors. As a stepper motor (19) rotates the drive member to pump fluid (13), a single optical sensor (30) senses the disk and provides signals indicative of whether a transparent sector or an opaque sector is being detected. A processor (21) counts the number of motor steps in the detected transparent or opaque sector and based on the number of counted steps in a type of sector detected or the number of steps counted when a state change to the other type of sector occurs, determines the motor position.