FPGA-based approach for change detection in GTAW welding process

Abstract

This paper presents the development of an FPGA-based platform for online discontinuity detection in a Gas Tungsten Arc Welding (GTAW) process, through the monitoring of its voltaic arc, using an optical infrared sensor. The FPGA-based platform uses a hardware/software co-design approach, in which the hardware part includes a change detection peripheral, apart from general purpose peripherals (e.g. UART, timer) and several customized ones such as memory for storing discontinuity data, timer and an ADC driver. The change detection peripheral comprises the filtering stage and the stopping rule stage, which include a Kalman filter and a cumulative sum (CUSUM) module, respectively. The overall system includes several processes running concurrently in the Microblaze embedded processor and several customized hardware modules, using floating point representation. In order to validate the FPGA-based platform, several experimental tests in the field have been done by introducing intentional discontinuities in the weld bead. These experimental results have shown a suitable performance of the overall system in the online discontinuity detection task. In this paper, the change detection peripheral is described as well as the synthesis results related to performance and resources consumption. In the overall co-design approach, the software part includes a MicroBlaze soft processor to control and manage the overall platform, including the interface issues.