Velocity-controlled shape-tracing system using eight optical sensors

A novel two-dimensional shape-tracing system was developed that uses eight optical sensors and two stepping motors. Each optical sensor, which consists of an optical fiber and a Darlington phototransistor, senses the intensity of the reflected light from drawings to determine the motion pattern of stepping motors. A software velocity-control scheme was also considered, because the shape-tracing system was designed mainly for an automatic plasma arc cutting process. By programming the control software in assembler language, a maximum pulse frequency of 2000 pulse/s, which is equivalent to a 4.8-m/min linear velocity, could be attained in the developed system. The developed shape-tracing system can be applied not only for the plasma arc cutting process, but also for other shape-tracing processes, such as for cutting clothes