A catheter procedure system comprising: a base; and a robotic mechanism (212, 312) having a longitudinal axis and being movable relative to the base along the longitudinal axis by an active linear drive mechanism, the robotic mechanism comprising: a robotic drive base (220, 320) including at least one drive mechanism; a cassette (114, 222, 322) operatively secured to the robotic drive base; a rigid guide (218, 318) coupled to the cassette; a flexible track (216, 316) suitable to support a catheter so that the catheter can be advanced into the patient without buckling, wherein the catheter is used to guide other elongated medical devices, wherein the flexible track has a distal end, a proximal end and a plurality of reflective sections (395, 495) spaced from one another by non-reflective sections (397, 497), wherein each reflective section have a first width and each non-reflective sections has a second width, wherein at least a portion of the flexible track is moveably disposed within the rigid guide; and a position detector mounted to the robotic drive base and positioned beneath the flexible track, the position detector configured detect light reflected off of the reflective sections of the flexible track and to determine the position of the distal end of the flexible track relative to the robotic mechanism based on the detected reflected light. a base; and a robotic mechanism (212, 312) having a longitudinal axis and being movable relative to the base along the longitudinal axis by an active linear drive mechanism, the robotic mechanism comprising: a robotic drive base (220, 320) including at least one drive mechanism; a cassette (114, 222, 322) operatively secured to the robotic drive base; a rigid guide (218, 318) coupled to the cassette; a flexible track (216, 316) suitable to support a catheter so that the catheter can be advanced into the patient without buckling, wherein the catheter is used to guide other elongated medical devices, wherein the flexible track has a distal end, a proximal end and a plurality of reflective sections (395, 495) spaced from one another by non-reflective sections (397, 497), wherein each reflective section have a first width and each non-reflective sections has a second width, wherein at least a portion of the flexible track is moveably disposed within the rigid guide; and a position detector mounted to the robotic drive base and positioned beneath the flexible track, the position detector configured detect light reflected off of the reflective sections of the flexible track and to determine the position of the distal end of the flexible track relative to the robotic mechanism based on the detected reflected light. a robotic drive base (220, 320) including at least one drive mechanism; a cassette (114, 222, 322) operatively secured to the robotic drive base; a rigid guide (218, 318) coupled to the cassette; a flexible track (216, 316) suitable to support a catheter so that the catheter can be advanced into the patient without buckling, wherein the catheter is used to guide other elongated medical devices, wherein the flexible track has a distal end, a proximal end and a plurality of reflective sections (395, 495) spaced from one another by non-reflective sections (397, 497), wherein each reflective section have a first width and each non-reflective sections has a second width, wherein at least a portion of the flexible track is moveably disposed within the rigid guide; and a position detector mounted to the robotic drive base and positioned beneath the flexible track, the position detector configured detect light reflected off of the reflective sections of the flexible track and to determine the position of the distal end of the flexible track relative to the robotic mechanism based on the detected reflected light.