... A drive system is being developed with 5 motors to move the tertiary. ... Shows the hysteresis in the motion. processing: ter/010116/doit.pro An incremental encoder is used for positioning on the tertiary with 2000 counts/turn (20000 cnts/inch vertical and 16000 cnts/inch horizontal,tilt). ... The horizontal and tilt drives have the same maximum velocity (3.5 in/sec) while the vertical drives can go at a maximum velocity of 2 inches/sec. ... Top plot is vertical drive, bottom is horizontal/tilt. ...