| Ultrasonic testing is a very important detection method in the area of non-destructive testing (NDT). It has been widely used in manufacturing, iron and steel metallurgy, metal processing industry and chemical industry, such as those require defecting detection and quality control areas. It also widely used in aerospace, rail transportation, ship navigation, boiler and pressure vessel, such as in-service safety inspection and life assessment fields. In addition, the ultrasonic detection technology has also been a preliminary application in the field of geological exploration, such as geological structures, rock formations, disaster prevention and environmental protection.In this paper, the ultrasound physics detector for the detection of simulated lunar soil structure is study designed, according to the present situation of the "Chang’e" moon exploration project in our country and the advantages of ultrasonic non-destructive testing technology and its’ application of mature technologies. Expectations through the experimental detection research to obtain valuable results on the shallow structure of the simulated lunar soil on Earth, for the actual soil structure and composition of the lunar surface, analyze the elements on lunar surface, useful minerals and the distribution of the material type has an important instructive, more conducive to the implementation of the research program of manned space flight and lunar exploration lunar surface.In this paper, the system design divided into three parts:a main control unit, ultrasonic transmitter device and the ultrasonic receiver device. The full text of system design uses a modular design concept. The main control unit design includes a micro-controller module, a clock module, a display module, a data storage module, a data communication module and power module. The ultrasonic transmitter design includes the design of the isolation module, the design of the drive module and the boost module. The ultrasonic receiver design includes the design of the limiter module, the former gain module design, the design of band-pass filter module, programmable gain module design, the design of signal conditioning modules and A/D converter module. In the main control unit design, the design of the micro-controller module is the processor STM32F103VET of the ARM Cortex-M3core as the core of the whole system of control, intelligent control system; the clock module is designed using the RTC real time clock in the microcontroller STM32F103VET on-chip control module, controlling the timing functions of the instrument systems; the display module design uses a TFT LCD screen, realizing the system display interface; the data storage module design uses a SD card storage, automatic storage system test data; the design of the data communication module is designed using the USB communication, transmitting the system test data to the computer client terminal software; the design of the power supply module is a battery with some low dropout linear regulators, to provide the required power supply voltage for the entire system. In the ultrasonic transmitter device, the design of the isolation module is used a component of the magnetic coupling isolation, achieving the separation between the ultrasound transmit signal with the microcontroller; the design of the drive module is used the ADP3625integrated driver IC, to drive the MOSFET component; the boost module’s design uses a MOSFET push-pull conversion circuit and the pulse transformer to achieve boost pulse signals, incentive ultrasonic transducer transmits ultrasonic. In the ultrasonic receiver, the limiting module design uses diodes and regulator diodes, complying with limiter high-voltage signal that may exist in the ultrasonic echo signals to protect the level echo receiving circuit; the former gain module design using the AD8250chip which is an instrumentation amplifier with programmable gain, to achieve effective reception of the echo signal and gain control; the design of band-pass filter module is used a high performance op amp AD8099which is designed into a voltage-controlled voltage source second-order band-pass filter to filter out the interference signals in the ultrasonic echo signal; the programmable gain module design uses analog switches of the multiplexer ADG1604and op amp AD8099to achieve the ultrasonic echo signal automatic gain control; the design of signal conditioning module is used in the OPA2335op-amp designing a signal differential conversion circuit to realize the ultrasonic echo signals level-shifting before A/D conversion; the design of A/D converter module is using the system microcontroller STM32F103VET chip integrated12-bit A/D converter to achieve sampling of the ultrasonic echo signal.In this paper, by debugging and testing the main control unit of the system, the ultrasonic transmitter, the ultrasonic receiver and the various functional modules, the results showed that the overall design of the system have reached the basic requirements for system design, its corresponding function, and completed the prototype design of the system.In this paper, the main content of the subject is designed prototype of the ultrasonic physical detector system in simulated lunar soil structure detection. The mainly completed works as follow:1. Learn the basic theoretical principles of ultrasonic testing, to master the application of ultrasonic testing; 2. According to the principle of ultrasonic testing, combined with the system design requirements to build the framework of the overall system design;3. According to the principle of system design framework, study design system main control unit and its functional modules, including hardware design and software design;4. Study design the ultrasonic transmitter device and its functional modules, including hardware design and software design;5. Study design the ultrasonic receiver device and its functional modules, including hardware design and software design;6. Respectively, to debug and test the main control unit, the ultrasonic transmitter and ultrasonic receiver as well as their functional modules;7. Jointed debug the main control unit, the ultrasonic transmitter and ultrasonic receiver for system tasting;8. Complete system prototype. |
