Research On Intelligent Dual-frequency Metal Detector

With the rapid development of micro-electronics and computer technology, the traditional metal detection systems are moving toward a new direction of renovating and developing. The initial metal detectors are mainly used in industrial detect and military mine-detection, but now are widely used in travel security, such as the quality and safety testing of food,textiles,wood,toys,medical production etc. With the continuous advancement of technology and the effect of metal detectors in social life, how to enhance the capability of metal detection equipments, become an urgent issue in that area.The purpose of this paper is to design a dual frequency digital metal detector system. It not only can detect the magnetic metal, but also can detect the non-ferrous metal with high accuracy. With in this, it changes the single type and low accuracy of ordinary metal detectors from working mode. This detecting system use multi-channel synchronous Direct Digital Synthesis (DDS) technology to produce sinusoidal signal, through the eddy current sensors detects metallic material. Use TMS320LF2407 system as CPU, achieving autoconditioning system parameters with self-learning algorithm. This paper also designs a good man-machine conversation interface to improve the readability and maneuverability of the metal detectors.This paper explains the system detailedly from two aspects: theory analysis of metal detection and designing of dual-frequency metal detector. The former one discusses the scope and phasic characteristic of metal material from electromagnetic field, and educes a conclusion of detecting frequency and different metal have pertinence. In this paper, the design of the system is divided into three major parts: the working principle and collectivity conformation of detecting system,system hardware designing, system software designing. In the first part, mainly expatiate the working principle and realization project of the whole system; the hardware designing part from detecting and controlling circuit go into particulars the design process of sending,incepting,demodulation and eddy current sensor. Especially introduce the interface designing of DSP and SCM., including SCI bunch interface corresponding hardware circuit designing, which is base on RS-485; in software design, mainly expatiate the DSP system and man-machine conversation program flow in CCS, u-Visin, and described the realization of self-learning methodological process, and then expatiate the software designing of SCI bunch interface communication.Finally, this paper gives the results of system testing. From the analysis of experiment, the dual frequency digital metal detector system not only can detect the magnetic metal, but also can detect the non-ferrous metal with high accuracy; The entire system's readability and maneuverability are good;, easy to upgrade expansion; cost effective and has a good prospect.