| Unexploded ordnance is usually located below the surface,mainly for armed conflicts,military exercises and range experiments are left on the scene after a variety of unexploded or abandoned ammunition.The materials used to make up these munitions will degrade over time,and the possibility of accidental explosion will increase,and the threat may last for generations.In addition,the war between countries is often determined by air supremacy.The rapid detection and positioning of unexploded ordnance will directly affect the progress of airport repair,and then have an important impact on the competition for air supremacy.The rapid and accurate unexploded ordnance detection device also has certain military significance to some extent.The work of this paper is divided into the following points :The feasibility study of the frequency domain unexploded ordnance detection system is carried out,including three aspects,sensor design and optimization,response signal research,detection platform construction and experiment.A multi-receiving coil sensor which can eliminate the influence of primary field is designed by analytical solution and simulation method,and the size of the sensor is optimized.The response signals of unexploded ordnance in different places around the sensor are simulated and analyzed.The feasibility of using frequency domain electromagnetic method to detect the existence of unexploded ordnance is verified,and a simple horizontal vertical positioning method of unexploded ordnance is given.Based on the high-performance impedance analyzer,an unexploded ordnance detection platform was built.The response signals of each receiving coil during the detection process were experimentally analyzed,which further verified the feasibility of the frequency domain electromagnetic method for unexploded ordnance detection.The hardware and software of the frequency domain electromagnetic unexploded ordnance detection system are designed.The hardware part is composed of transmitter and receiver.The transmitter circuit includes DAC conversion,voltage amplification and power amplification circuit.The receiver circuit includes instrument amplifier,anti-aliasing filter,programmable gain amplifier and AD conversion circuit.The software part includes excitation generation module and signal receiving module.The Kintex-7 series FPGA is briefly introduced.The DDS is used to realize the occurrence of a certain frequency sinusoidal signal of the transmitter.The AXI protocol is described.The principle of digital phase sensitive detection is described.The Ethernet communication implementation process of the MK7160 FA development board is described in detail.The detection platform of unexploded ordnance detection system in laboratory environment is built,and the function of the designed frequency domain electromagnetic unexploded ordnance detection system is tested.The sensor is a self-developed electromagnetic sensor.The DAC conversion,power amplifier circuit and AD conversion circuit are tested respectively to verify the function of the circuit and the data exchange between the hardware circuit and the PC.The whole system is tested,and the unexploded ordnance within 0.5 m can be detected stably. |
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