| The object of this thesis is a kind of temperature sensor made of a thin-walled tubular nonmagnetic material.Because its wall thickness and thickness uniformity have a significant impact on sensors’ response speed,product quality and yield,its thickness measurement is of great importance.The thin-walled thickness gauges developed in the previous stage can measure only one point at one time.To measure the thickness of various positions,the probe needs to be moved continuously,which results in lower measurement efficiency and damaged specimen.In this thesis,a multi-probe thickness measurement scheme is proposed to solve this problem.In this method,Multi-point thickness values can be obtained rapidly and accurately,and thickness uniformity can be judged as well.In the design of embedded multi-probe thickness measurement system,the measurement principle,system hardware and software fdesign were studied.Firstly,the principle of thickness measurement based on Hall effect is analyzed-According to actual demands of measurement,a reasonable choice is made on sensors devices like Hall sensors,magnets and steel columns.When designing multi-probe spatial layout and internal structure of probes,ANSYS,a type of finite element simulation software,is used to modeling and simulating various situations,like a single magnet,a single magnet and steel columns,multiple magnets and steel columns,the top of the magnet plus horizontal magnetic,etc.Combined with experimental measurements,the final layout,one top magnet and four horizontal probes,is obtained.And the distance between magenets and Hall sensors is 7mm.As for embedded system hardware design,STM32F103ZET6 is used as the processing unit.External 3.5-inch resistive touch screen is used as human-computer interaction platform.RS-232 serial port and ESP8266,a serial port to wireless network module,are provided to achieve communication with the PC.OP07 integrated operation amplifiers are used in signal processing circuit.In the aspect of embedded software design,C/OS-III multi-task real-time operating system and STemWin graphics system are transplanted on STM32F103ZET6.On this basis,I write each task program to achieve system functions,like signal acquisition,thickness calculation,results display,communication with PC,warning alarm,relative information inquiry and other functions.PC software is developed in Visual Studio 2010 and Microsoft MFC application development framework.At the end of this thesis,experiments and tests are carried out on the multi-probe thin-wall thickness gauge.The result shows that this system can achieve the multi-point rapid measurement for the thickness of the thin-walled tubular non-magnetic material mentioned above with the measuring range of 0-5mm and the measuring accuracy of 0.2mm. |
