Research On Real-Time Compression Technology Of Pipeline Magnetic Flux Leakage Inspection Data

Magnetic Flux Leakage (MFL) inspection is the main method of on-line inspecting long distance oil-gas transportation pipeline. Pipeline MFL inspection device is applied to detect defects of pipeline in time in order to prevent pipeline leakage accident. Because of MFL data storage used in electronic data storage hard disk volume, it has required real-time data acquisition, compression, storage systems In this paper, an embedded system based on ARM (Advanced RISC Machines) is developed with Linux embedded technology, the system is used to realize the real-time acquisition, compression and storage of pipeline MFL inspection data.First, the defects of current MFL inspection system aiming at the defects, a new system design scheme which applys FPGA is presented, and the hardware system based on a single ARM is designed according to system requirements. The aim and application of diagnostically lossless compression and the data compression method for magnetic flux leakage (MFL) inspection of pipelines is introduced. By analyzing the principle of MFL and the character of the MFL inspection data, uses the LZW algorithm to magnetic flux leakage data in real-time lossless compression. In order to accelerating the speed of data compression, the algorithm also uses Hash method to manage the string table of LZW algorithm. Based on Linux, the drive program of acquisition device is developed and the system software implementing data acquisition, compression and storage is designed with multithreads technology.Utilizing ARM technology, hardware & software co-design can be employed freely; In the same time, reliability and operation power of the system are improved greatly via applying ARM to control data acquisition module; Besides, the utilization of Linux operating system enhances the acquisition precision of frontal data, simplify the communication between ARM and peripheral equipment, shortens further system development time and reduced design cost. The algorithm can realized more than 2 times the data compression. The real-time of the program is better, and the program realized 2 times more data compression. And the realization of magnetic flux leakage data acquisition, compression, storage. Aiming at each functional module designed in the system, testing methods and corresponding results are presented respectively in the paper. Experiments indicate that each functional module can run stably with good performance, and they can be used in the pipeline MFL inspection device with no problems.