| GMAW has good process performance and is widely used in engineering fields such as ships and petrochemicals.In actual production,the irregular operation of employees may cause fluctuations in the products' quality.So it is of great significance to realize the real-time monitoring of the welding process.Due to a large amount of data needs to be transmitted during the monitoring process,it places high requirements on the data transmission capacity of the system under limited communication bandwidth.Based on the above engineering requirements,this topic developed a wireless monitoring system for welding process applied to GMAW,and designed a compression algorithm with high compression ratio and low error rate to deal with the problem of large data transmission.Firstly,the domestic and international development status of the welding online monitoring system and data compression algorithm are analyzed and discussed.Based on the system's functional and performance requirements and the most suitable wireless transmission scheme,the overall design of the welding wireless monitoring system is determined.Secondly,design the software and hardware of each module in the monitoring system,including signal conditioning,data acquisition,data processing,data transmission,data reissue,field information collection,and power-down storage modules.In terms of hardware,the system uses STM32 as the data processing core;AD7606 realizes real-time synchronization and high-precision acquisition of welding signals;M8321 wirelessly transmits and receives data through 4G networks;SD cards can communicate on 4G networks Store data in time when problems occur and reissue data after communication is restored;1900GSR module uses two-dimensional code technology to quickly input welding site information;DS3232 completes power-down storage of configuration information.In terms of software,the system has transplanted the ST official driver as the underlying driver layer of the system;the operating system layer has transplanted the Free RTOS embedded real-time operating system for system task scheduling and management;the application layer has designed the system tasks,message queues,and main programs and Developed a data communication protocol between the upper and lower computers.Thirdly,this paper summarizes the characteristics of GMAW welding signals,finds their potential compressible factors,and determines the design ideas of the compression algorithm for these factors.A three-layer compression algorithm with high compression ratio and low error rate is proposed.The GMAW signal is deeply compressed through neighborhood substitution,lifting wavelet piecewise constant compression,and CSN encoding.At the same time,an algorithm based on cumulative reduction error is designed to optimize the three-layer compression algorithm,and the algorithm is simulated and verified by MATLAB.It is found that compared with the existing compression algorithms,this algorithm achieves a large improvement in compression performance while maintaining a lower error rate than the original algorithm.Finally,the system is applied to the on-line monitoring of welding process stability.The characteristic parameters extracted from real-time welding data are analyzed,and a Lab VIEW monitoring interface based on these parameters is designed.The accuracy and effectiveness of the wireless monitoring system is proved through multiple sets of welding tests.At the same time,the real-time data collected by the monitoring system were used to diagnose online the welding stability and weld formation quality during the test. |
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