Design And Implementation Of Inductive Balanced Metal Detection System

Metal detection is a technique for detecting metal objects.It uses the principle of electromagnetic field eddy current sensing to realize non-contact detection of metal objects through induced signals generated by metal.With the continuous improvement of detection technology and signal processing methods,metal detection technology have been widely used in industrial,security and other related fields.At the same time,higher requirements are also placed on performance indicators such as sensitivity and anti-interference of metal detection systems.In this paper,based on the research of metal detection technology at home and abroad,the eddy current sensing principle of the inductive balanced coil is used as the design basis of this system.For the problem that the detection sensitivity is not high enough and the anti-interference ability is not strong in the metal detection system,an induction-based balance coil scheme is proposed.The metal detection system of the detection coil improves the sensitivity and anti-interference ability of the system through digital signal processing.First,combined with the functional requirements of the metal detection gate and the design requirements of the detection system,the overall scheme design of the inspection system is completed.The system simulation part needs to consider the influence of signal frequency on detection performance,the matching of the transmitting and receiving balance coils,and the analog signal filtering power amplifier.The digital part of the system needs to design the metal detection algorithm and the signal processing flow.At the same time,the system involves the transmission and reception signal processing and the detection result display.The interaction design of the protocol/state machine between the transceiver signal processing board and the display screen needs to be determined,thereby determining the FPGA implementation scheme.Secondly,using hardware design tools such as ISE,modular design is used to complete the design of the signal processing flow and the hardware implementation of the entire system.The hardware implementation of the system is coordinated by Spartan-6 FPGA and Artix-7 FPGA.Spartan-6 mainly completes the generation of transmitted signals,system state jump control and peripheral device interaction functions.Artix-7 mainly completes signal acquisition.Signal processing such as demodulation,filtering,calibration,and detection.The data and information are exchanged between the FPGAs through the UART interface,and the FPGA communicates with the host computer through the UDP interface.Finally,in the actual application scenario based on the detection of the door prototype,the relevant performance test and analysis of the metal detection system is performed.