Estimation of Software Testing Costs and Risks Using Fuzzy Techniques

A high density spiral track forming apparatus according to the present invention includes a linear motion mechanism for moving an optical recording system in a radial direction of a disk-shaped substrate, and a length measurement machine for detecting the distance travelled by the optical recording system in the radial direction of the substrate disk. The apparatus further includes a velocity computing device for detecting the travel velocity of the optical recording system according to the detected result of the length measurement instrument, and a velocity control device which detects the difference between the travel velocity of the optical recording system which is detected by the velocity computing device and a predetermined velocity, and controls the linear motion mechanism so as to eliminate that difference.