The Design Of Data Acquisition System For Laser Welding Based On USB

Laser welding is a highly complex chemical and physical process. In order to increase the stability and to maintain the quality of laser welding, it is an important act that the laser welding process should be monitored and controlled in real time. And to detect and analysis signals that reflect the welding quality in process of laser welding is an important method to do so. Visible light that reflects the plasma status, infrared signals from the welding pool and the plasma sound are selected as sensing signals to design a signal acquisition system for laser welding based on USB in the thesis.The protocol of USB 2.0 is introduced firstly, including bus attributes, data flow model, enumetation and so on. Then the signal acquisition system for laser welding based on USB is studied on both hardware and software. The thesis focuses on the design of the data acquisition module based on USB in hardware design segment. In the data acquisition module, USB interface chip CY7C68013 with on-chip microprocess is used to communicate between device and the host. Also a highly integrated chip of FPGA is used as the control core of data acquisition and communication. Then the hardware design scheme of the data acquisition module is given in detail. The software programs mainly include firmware, USB driver and application program. During the firmware development, Slave FIFO and auto communication are used to increase the transmission rate based on the FX2 firmware framework. In the part of driver program, WDM and system structure of USB driver based on WDM are introduced and the development process of USB driver of the system is given. At last, the application program based on USB driver is designed for system test and can acquisit data and display waveforms. Experiment results indicate that the system can provide correct data acquisition and can correctly reproduce the state transition of laser welding.The signal acquisition system for laser welding based on USB discussed in the thesis has excellent features of both flexibility of FPGA and high speed and convenience of USB. It provides a method of economic and convenient of data acquisition for laser welding.