| Pigging is an important means to ensure oil and gas pipeline transportation.Intelligent PIG(Pipeline inspection pig,pipeline robot)has been widely used in oil production and transportation system because of its advantages of adapting to a wide range of pipeline diameters,requiring no pipeline to shutdown and the abilities of integrating online pigging and testing modules.Drive and speed regulation are the core functions of pipeline robot.However,the traditional speed regulating devices mostly use the bypass valve structure for unloading speed regulation,resulting in the complex structure,huge volume and limited axis space of the robot which is difficult to satisfy both size and function requirements of the robot.At the same time,the traditional ultrasonic eddy current and probe detection methods have high requirements for robot installation space and cost,which are difficult to be applied to the miniaturized intelligent pig system.In order to solve the above problems,this thesis proposes smart pig cup that integrates the driving and the sensing functions(SPC).The designed and processed test prototype is analyzed and tested by means of model derivation,numerical simulation,image processing and experiment,and the speed regulation driving ability of the cup and the recognition performance of obstacle characteristic parameters in the process of dynamic obstacle crossing are also studied.The major research contents of this thesis are as follows:(1)This thesis summarizes the research status of pipeline robot both domestically and aboard,investigates the existing pig cup driving technology and speed regulation principle,and analyzes the advantages and disadvantages of speed regulation methods.The existing pipeline internal detection principles and methods are sorted out.According to the review results,the targets of the research are then set.(2)A SPC is designed to realize the adjustable running speed of the device and to integrate the pipeline obstacle detection function.A numerical model of the pig stress-strain analysis is developed,and the pig flow field under steady-state conditions is studied numerically.The characteristic functions of the SPC under pipe wall obstacles is also established.(3)Experimental research is carried out,to process and manufacture a SPC sample.A model pipeline is built to simulate the deformation condition of the cup structure under pressure.The electrical circuits for motion control,data acquisition and signal amplification are also built in the lab.An image processing program is established to realize the strain analysis of the cup under compression boundary conditions.(4)The experimental results are analyzed,and the numerical results from the structural strength and flow simulation of the system are also studied.The function of the SPC is experimentally verified.The signal characteristics of the SPC sensing system during obstacle traversing are also studied,to construct the mathematical model between the obstacle parameters and the strain gauge voltage.Finally,effective detection and identification of pipeline obstacles in the simulated experimental environment is achieved. |
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