Research On Above Ground Marking Of Pipeline Inspection Device Based On MEMS Vector Acoustic Sensor

With the rapid development of pipeline technology, the ground marker of pipelineinspection device has a swift and violent development trend. The ground marker technologybased on acoustics principle has become the hotspot and difficulty of the research currently.Search for the suitable acoustic sensor is the core of this technology. MEMS vector acousticsensor is a novel sensor developed by the North University of China, which has theadvantages of vector, small size, high sensitivity, good stability, low cost and so on. Based onthe above background, MEMS vector acoustic sensor has been applied in the ground markerinnovatively. It is a breakthrough from the sea to the land for the MEMS vector acousticsensor.On this subject, the spread mechanism of the acoustic signal in soil environment hasbeen studied firstly. According to the Biot theory, the form of the acoustic waves in soilenvironment has been derived, then analysis of the characteristics of the various wave forms.The result of the analysis is that the fast longitudinal wave is the main form of the acousticsignal. Then analyses the features of acoustic signal which sent out by the inspection deviceoperating in the pipeline.On the basis of the above analysis, in the view of the special features of the acousticsignal and the soil environment, optimization and improvement has been done for the MEMSvector acoustic sensor:1. design the orange petal type structure to improve the sensitivity;2.long cylindrical structure to increase the coupling of the sensor and the soil.Further, the performance of the single MEMS vector acoustic sensor has been simulated.Firstly, the good directional ability of the sensor has been simulated. Secondly, we design theexperiment to verify the good performance by using the beam forming method. The resultsshow that the average error is limited to5°. On the basis of the single sensor signal processing and experimental analysis, the variousperformance of the array is carried out by computer simulation and experiment, whichcontains the multi-source resolution and arrival angle resolution. Firstly, the array form andthe specific parameters of the vector array have been theoretical analysis and calculation.Secondly, the directionality, multi-source resolution, arrival angle resolution have beensimulated by the computer then analysis of the influence factors. Finally, the experiment hasbeen done to verify the simulated results. Preliminary verified the feasibility of the estimatingsound source. However, the results of the experiment are not so good which is affected by theconsistency of the sensors. The experiments result require MEMS vector acoustic sensorimprovement. It is hope that this research can play a role in promoting the engineeringapplication of the above ground marking of pipeline inspection device based on the MEMSvector acoustic sensor.