Reaserch Of High-Precision Metal Detector Based On Digital Signal Processor

Metal detector is a kind of special instrument which is used to detect and remove metal in the materials, and is widely used in areas such as mining, metallurgy, food processing, medical, textile, and so on. In recent years, with the continuous improvement of people’s living standards, the public health conscious enhanced significantly. Meanwhile, the frequent exposures of the food safety problems make citizens pay more and more attentions to the safety of their daily food and drug. After all, it is closely related to their health, once some metals are mixed into the food or drugs, or something else, it may cause serious consequences.Besides, in some industry areas, the purity of material is especially important. If some metal impurities such as tiny screws are mixed into it, the machine can be possibly damaged, and resulting in huge economic losses, so the existence of the metal detector seems to be very important. However, reviewing the industries of our country, excellent products which are comparable with foreign advanced metal detector can be rarely seen. High-precision metal detectors are still mainly rely on imports, which are very expensive. Based on this embarrassed situation, it is so meaningful to design a set of metal detect system which with high-performance and low-cost, that we can break the technological monopoly of foreign countries.This paper based on the view of the whole actual project, through rigorous theory analysis of the basic characteristic of current-carrying coil’s magnetic field, established a complete mathematical and physical model to imitate the process of metal through the coil. Even more, select the structure of improved balance coil as the sensing probe. In addition, digital signal processor TMS320F2812has been chosen as the central processing unit by its powerful data processing capability. Meanwhile, with the assist of other functional circuit module, such as power supply part, signal transmit/receive part, wave filtering and amplifying part, A/D part, and so on. At the same time, the software system is introduced clearly. Next, with the manufacture of the printed circuit board, an experimental platform with control system, balance coil system and transmission system has been established. Further more, numerous experiments have been taken place on this platform and lots of important data have been dealt. Also, the problems exposed in the experiments are analyzed in purpose of how to avoid them. In this paper, appraisal reports are also added, as a basis of its performance test and evaluation.At the end of the paper, the author made the outlook of the development of metal detector, and summarized the valuable experiences at home and abroad. Finally, based on the shortcomings which still exist, further improvements methods have been given.