Research On Design And Control Method Of A Speed-Controlled Pipeline Inspection Gauge

The safety of long-distance pipeline transportation of energy materials such as oil and natural gas is a vital problem related to the national economy and the people’s livelihood.Regular pre-inspection and maintenance of pipelines can effectively prevent the occurrence of safety accidents.At present,one of the important methods for pipeline fault pre-inspection is the internal inspection technology,which accuracy depends on whether the pipeline inspection gauge(PIG)has a stable operation speed in the pipeline.However,relevant domestic enterprises and research institutes are still in the stage of theoretical and experimental research.Few public information and limitative technically make the research on the speed-controlled PIG of great significance.In this thesis,the construction of the speed control system,the motion model and the speed control algorithm of PIG are studied.A speed-controlled pipeline inspection gauge with safety locking device is designed.The control algorithm is also studied based on the motion model of the PIG under gas medium.The specific research work is as follows:Firstly,this thesis summarizes the speed control technology of PIG,mainly including the research background and significance,the research status of speed control theory,and a brief introduction to the difficulties in the development of speed control system.Secondly,according to the functional requirements of the PIG,an overall scheme of the control system is designed,including the design and implementation of the core control board based on dual arm chip,PC application software,control algorithm and its working mode.Then,in view of the gas medium environment,combined with the analysis of the movement mechanism,a mathematical model describing the oscillation movement of the PIG is established,and the validity of the model is verified.Finally,based on the mathematical model of the PIG,the algorithm suitable for the speed control of it is analyzed and designed step by step.Since the model established in this thesis is a self-instability model,the effect of introducing zone control is not as good as that of traditional PD control.Therefore,this thesis introduces the feedback correction to improve the stability of the system,and studies the interval control of the stable system,so as to achieve the purpose of less action of the actuator and increase the endurance.Considering the model of pipeline inspection gauge becomes uncertain due to many kinds of interference in the pipeline,which leads to poor control effect,fuzzy control is introduced on the basis of zone control.And simulation results show that zone-fuzzy control is more suitable for the speed regulation of it.In the end,the thesis made a whole summary and presented the future prospect on further study.