Research On Technology Of USB And Application In Digital Fiber Plug Gauge

It is necessary to measure the diameter of holes in order that high precision and excellent performance of interchangeability can be gained in mass productions. The efficeincy is contrary to the precision in measurement. Gauge and vernier caliper both have the advantage of high efficiency, however vernier caliper is only qualified for applications of relatively lower precision. Gauge can only provide the dimension of the part in tolerance zone, and the problem of abrasion will arise when constantly used. To overcome the disadvantages mentioned above and improve the precision and efficiency of measurement, a new solution of digital fibre plug gauge with USB is presented in this thesis.There are a lot of interfaces in personal computers currently. USB device has the advantage of PnP, auto configuration and high speed. USB is better than other interfaces in many ways.The digital fibre plug gauge makes use of fibre sensor to sense small changes of movement. The method of non-touching and relativity measurement is adopted. It can provide the hole size of parts quickly and accurately. The instrument is made of mechanical part, fibre sensor, hardware, software and a personal computer. The sensor is used to sense the small movement, then the movement is converted into the offset of voltage by the processing circuit, next the voltage is converted into digit by ADC, the number will be tranferred to the personal computer through USB again. The result will be showed on screen after processing at last.The thesis mainly deals with the whole realization of the instrument. The solution of digital fibre gauge with USB is advanced after the current state of the gauge and the technology of PC interfaces are carefully studied, then the task of the thesis isanalyzed.The specification of USB is discussed in chapter 2. The background, overview architecture and the model of dataflow and protocol of USB are presented in detail in this chapter.The overview design of the instrument is given out then. The theory of the instrument is showed in this chapter. All the parts and design tools are also supplied.The design of circuit is discussed in the part of hardware. It includes the application of ADu C824, PDIUSBD12, AD780, MAX232 and the function of the circuit.The programming of the application is discussed in the part of firmware. The overview architecture and detailed programming of the firmware are presented. At last the problem of debugging and development of AD u C824 is talked about.The software and hardware required on the host is discussed first in the part of driver, then the function and programming of the driver is presented. At last the installation of driver is concerned.How to access the device and transfer the data to PC are discussed in the part of applicaion. The GUI of measurement is also presented here.The experiment and calibration process of the instrument is showed in chapter 4. While the performance of ADC and the precion of the instrument are narrated in the portion of data processing.