A catheter procedure system includes a base and a robotic mechanism having a longitudinal axis and being movable relative to the base along the longitudinal axis. The robotic mechanism includes a robotic drive base including at least one drive mechanism, a cassette operatively secured to the robotic drive base, a rigid guide coupled to the cassette and fixed relative to the robotic mechanism and a flexible track having a distal end, a proximal end and a plurality of reflective sections. At least a portion of the flexible track is disposed within the rigid guide. The robotic mechanism also includes a position detector mounted to the robotic drive base and positioned beneath the flexible track. The position detector is configured to 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 based on the detected reflected light.