A new method for detecting pipeline deformation by an inspection robot with a moving 2D laser rang finder

Buried pipelines would be deformed as a result of the loading of surface facilities and vehicles. If the deformation has gone beyond the critical level, it may cause serious consequences, such as the damage of the pipeline. Pipeline deformation is also applied to estimate the stress in the pipeline, and thus to keep the pipeline stress below the critical level. A new method for detecting pipeline deformation by an inspection robot with a laser range finder (LRF) is presented in this paper. The robot posture changes instantaneous when the robot is running in the pipeline, which makes the deformation detection difficult. To calculate the deformation rate of the pipeline, the moving frame of the robot, the base frame on the pipeline, and frame of the LRF are established and their transformation matrix are deduced with the posture angles of the robot detected real-time. After the range data collected by the LRF are transformed to the base frame, a least squares method is used to fit the ellipse function. With the fitted ellipse function, the ellipse can be drawn and the deformation rate can be calculated easily. Experiments by the inspection robot in real pipelines are carried out and the results show that the proposed method is useful and valid.