| As an advanced practical means for nondestructive detection, CT technology has been widely used in many fields, such as medicine, spaceflight, aviation, military industry, material, steel, geology, and so on. And it is a rising interdisciplinary integrated technology, which refers to much multidisciplinary knowledge, such as nuclear physics, electronic technology, precision machinery, control technology and computer image processing. CT teaching experimental instrument is a pint-sized CT equipment with intact function, which is developed for reflecting the CT technology principle clearly. It not only can be used for college teaching experiments, but also can be used for nondestructively detecting for small workpiece. CT teaching experimental instrument consists of ray source system, detection system, control system, machine system and image processing system. And the control system needs to complete motion control of the machine system and data acquisition of the detection system, which is the nerve centre of the entire instrument. Since the performance of the control system directly affects the quality of CT image, research and design of the control system is a key of development of the entire instrument.This paper introduced the characteristic, research actuality and basic principle of the CT teaching experimental instrument. It was analyzed that the scanning detecting mode, structure and main performance of a new generation CD50BGA+ CT teaching experimental instrument. Noise and its source, which impacts on the performance of instrument badly, were discussed. According to the design request of control system, parameter target of key elements were calculated, the design project of motion control, data acquisition and communication was analyzed.Based on the analysis, the control system of CD50BGA+ CT teaching experimental instrument was designed, including hardware design and software design. The hardware included several circuit modules, such as microcontroller, CPLD circuit, step motor drive and control, USB interface, and so on. The software included acquisition control program in computer, rock-bottom control program in microcontroller and communication protocol.Lastly, the control system and the instrument were debugged and tested. Test result shows that the function of control system is achievable and the performance of it is stable.Comparing with conventional CT teaching experimental instrument, CD50BGA+ CT teaching experimental instrument is not only more advanced in performance, but also lower in cost, smaller in cubage, more convenient in use and stronger in function. At present, the instrument has been used by several universities for teaching experiment. |
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