Research On Gas Pipeline Inspection Robot And Its Motion Control

Pipe inspection robots as a member of special robots, which integrate intelligent mobile robot technology and nondestructive testing technology, are developed for inspection, spray painting, jointing, and cleaning up in gas/oil pipeline. These robots can carry NDT devices and tools, and enter pipeline, which is a difficult and dangerous environment for human, to finish some tasks on-line for security of pipeline instead of human, such as inspection, cleaning up, and maintenance into. Especially, they appear more useful for inspection in some special pipelines which are buried underground across the river, railway, and road. Therefore, developing pipe inspection robots is significant for science, economy, and society, and attracts more and more attentions of researcher and government in many countries. Today, pushed by many investigations in the past years, the technologies of pipe inspection robot has got a rapid improvement. However, in the view of current level in technology, the research on pipe inspection robot is still in the developing stage both in China and other countries, and many research achievements are prototypes only staying in laboratory, which exist a wide gap in industrialization and practical application. Supported by the National High-Tech Research and Development Program of China (863 Program) (Grant No.2002AA422110), the Key Project of Science and Technology of Shanghai (Grant No.021111117), and Yunan Province-University Cooperation Fund (Grant No.2001KABAA00A025), considering the project goal to develop the gas pipeline inspection robot for inspection of Kunming Gas Company's main gas pipelines, the theoretic analysis and systematic research on gas pipeline inspection robot in actual gas pipeline with"T"branch, elbow pipe, and diameter-change pipe, are developed and described in this thesis, including in-pipe motion principle of robot, motion model, locomotion mechanism, kinetic character, navigation and control. A prototype of gas pipe inspection robot is designed and developed successfully. On the basis of a large amount of field experiments, its structure is improved, and the improved prototype has been developed. This can help to establish a good base to promote resolving some key technology problem of gas pipeline inspection robot in complex gas pipe environment. This thesis wants to contribute a further promotion for industrialization and practical application of gas pipeline inspection robot, and it is significant in safe inspection of urban gas pipeline, the safety of people's life and riches, and the stability of society.The main content and contributions of this thesis are summarized as follows:1. On the basis of collecting and mastering a large amount of documents and references on pipe inspection robot, the differences and characters of existing in-pipe locomotion modes are analyzed in detail. Considering the environment of pipeline and the demands of inspection, the exact locomotion mode, which is more suitable for gas pipeline environment, is selected through comprehensive comparison, and the related new locomotion mechanism of gas pipeline inspection robot is proposed.2. On the basis of the selected locomotion mode and the proposed locomotion mechanism, some topics of in-pipe kinetic character of gas pipeline inspection robot are analyzed and discussed deeply, including its in-pipe moving resistant, spatial motion equation, attitude change, radial adjusting, capability over obstacle, and in-pipe stability of motion.3. Aiming at the robot passing through elbow pipe and steering control in gas pipeline, the specifics of robot coordinated motion control in typical arc elbow pipe and steering control in"T"branch are discussed in detail. According to the defect of locomotion mechanism emerged in passing through elbow pipe and turning motion, the improved structure of locomotion mechanism is presented to be more suitable for moving in pipeline.4. In order to improve the intelligent level for the operation of the robot, the navigation strategy based on computer vision and independent location technology in gas pipe environment are investigated. According to the actual demand of gas pipeline inspection robotic system, a new remote information exchange system of gas pipeline inspection robot is established based on network to provide the bottom hardware support for robot remote control and information exchange. On the basis of this remote information exchange system, the remote control structure is discussed and described, and an exact remote control structure which is more suitable for gas pipeline inspection robot is proposed.5. An experimental prototype for gas pipeline inspection is designed and developed successfully, and its experimental research is implemented according to current experimental conditions. Aiming at the problem emerged in experiment, the improved design has been applied to prototype of robot, and the improved prototype has been developed. Based on electromagnetic flux leakage (EMFL), a nondestructive testing (NDT) technique with high precision for the detection of gas pipe wall thickness is presented, and the on-line NDT device adopting this technique is developed to provide optional mobile equipment carried into gas pipeline by robot. Through the theoretic analysis and experimental investigation for this device, the influences of some factors on thickness measurement are revealed, and the key parameters are obtained. According to experimental results, the improved structure of device is presented, and a new device adopting this improved design is developed.Although the major research project has been completed in this thesis, there still exists much research works to be done to make the system suitable for practical application. At the end of this thesis, the author makes a summary of the main research works and contributions, and give some suggests for further research.