Motion analysis and control of the pipeline robot passing through girth weld and inclination in natural gas pipeline

Abstract

In-pipe inspection and maintenance technology based on pipeline robots are effective means to achieve the safe transportation of oil and gas. The dynamic characteristics of the pipeline robot change when passing through the girth weld and changes in pipeline inclination, which can affect the accuracy of the detection results and cause damage to the robot. This paper studies the modular pipeline isolation plugging robot (PIPR). The Active Disturbance Rejection Control method based on the Whale Optimization Algorithm (WOA-ADRC) and a controller based on Sarsa(λ) algorithm were proposed to manage the influences of girth weld and pipeline inclination, respectively. The dynamic model of the PIPR under the action of fluid was established. Through dynamic simulation and experiments, the dynamic response of the PIPR passing through the girth weld was studied when its velocities and attitudes were changed. In addition, the relationships between the axial vibration caused by the girth weld and the velocities and attitudes were analyzed. The WOA-ADRC controller was proposed to control the motion of the PIPR to reduce the effect of the girth weld during movement. The velocity error could be controlled within 0.003 m/s through parameter optimization. To reduce the speed excursions of the PIPR caused by the changes in pipeline inclination, the Sarsa(λ) controller was proposed to adjust the PIPR's driving torque. The velocity error could be controlled within 0.034 m/s under the changes of pipeline inclination. The results showed that the axial vibration caused by the girth weld was more intense with the increase of the motion velocity. Furthermore, the axial vibration was the most evident when the attitude angle was 60°. The proposed methods could effectively control the motion of the PIPR when passing through the girth weld and change in inclination, which improved the reliability of the detection results.