Dynamic plugging regulating strategy of pipeline robot based on reinforcement learning

Pipeline isolation plugging robot (PIPR) is an important tool in pipeline maintenance operation. During the plugging process, the violent vibration will occur by the flow field, which can cause serious damage to the pipeline and PIPR. In this paper, we propose a dynamic regulating strategy to reduce the plugging-induced vibration by regulating the spoiler angle and plugging velocity. Firstly, the dynamic plugging simulation and experiment are performed to study the flow field changes during dynamic plugging. And the pressure difference is proposed to evaluate the degree of flow field vibration. Secondly, the mathematical models of pressure difference with plugging states and spoiler angles are established based on the extreme learning machine (ELM) optimized by improved sparrow search algorithm (ISSA). Finally, a modified Q-learning algorithm based on simulated annealing is applied to determine the optimal strategy for the spoiler angle and plugging velocity in real time. The results show that the proposed method can reduce the plugging-induced vibration by 19.9% and 32.7% on average, compared with single-regulating methods. This study can effectively ensure the stability of the plugging process.

Analysis on steering characteristics of crawler pipeline robot

In order to improve the elbow passing performance and different diameter adaptability of pipeline robot,a supported crawler pipeline robot is designed,which adopts screw nut mechanism and hinge four-bar mechanism to adapt to the complex environment such as variable diameter pipeline and elbow.The steering characteristics passing through the elbow are studied,the kinematic of pipeline robot bending steering is established,the geometric constraint(GC)and steering constraint(SC)in the elbow are analyzed,and the steering experiment is conducted.The results show that the robot can pass through the elbow by the SC model.The SC model can reduce the motor current and energy consumption when the robot passes through the elbow.

FMECA and FTA Methods of Reliability Analysis for Oil and Gas Pipeline Robot

In this paper,FMECA and FTA methods are presented for oil and gas Pipeline Robot in order to improve the reliability.Take a crawler pipeline cleaning robot as the research object.According to the robot′s variable working environment,high failure rate and short service life,in order to reduce the probability of its failure,and to extend its use time limit under the premise of being able to adapt to the complex working environment,and reduce maintenance cost of failure.To realize this purpose,FMECA analysis is fristly proposed,by which obtain the failure modes,causes and effects of each component mechanism,and identify the component mechanism with high risk and failure rate.Secondly,FTA is developed to establish the fault tree model of Cleaning and diameter changing mechanism,retain the underlying fault and the cause of its failure.Simulation results are carried out to illustrate the effectiveness of this proposed method and improvement measures to improve the reliability of the robot.

Traveling property of wheel-type pipeline robot with different configurations

In order to improve the travelling ability of the wheel-type pipeline robot in elbow section of pipeline, the model of drive ratios is proposed aiming at the pipeline robots with different configurations. Through the movement analysis of the robot with different configurations in elbow section, the pose model of the robot is established, and the coordinates of the wheel centers and the contact points can be got through the calculation of the pose model. Based on the pose model established, the corresponding drive ratios are obtained combining with the relations of the velocities of wheel centers and rotative velocities of wheels under the movement condition with no interference. The virtual simulations and prototype experiments are carried out, and the drive ratios accuracy of the model when the robot moved in elbow without interference is validated.

Localization technique research of a pipeline robot based on the magnetic-dipole model

The magnetic field distribution of an emission antenna is studied in this paper.When the slenderness ratio of the emission antenna is high,the emission antenna can be simplified as a magnetic dipole for practical application.The numerical results of the magnetic dipole magnetic field show that the magnetic magnitude distribution has a hump-shape,whose direction is perpendicular with the antenna axis direction.A localization method based on the hump-shape signal detection is presented.The experimental result shows that the precision can reach a value of±5 cm.The method can be used to localize a pipeline robot working in a metal pipe.

In-Line Inspection of Pipeline Defects Detection Using Ring-Type Laser

Pipeline plays a vital role in transporting fluids like oils, water, and petrochemical substances for longer distances. Based on the materials they carry, prolonged usage may cause the initiation of defects in the pipeline. These defects occur due to the formed salt deposits, chemical reaction happens between the inner surface and the transferring substance, prevailing environmental conditions, etc. These defects, if not identified earlier may lead to significant losses to the industry. In this work, an in-line inspection system utilizes the nondestructive way for analyzing the internal defects in the petrochemical pipeline. This system consists of a pipeline inspection robot having two major units namely the visual inspection unit and the power carrier unit. The visual inspection unit makes use of a ring-type laser diode and the camera. The laser diode serves as a light source for capturing good quality images of inspection. This unit is controlled by the Arduino in the power carrier unit which provides the necessary movement throughout the pipe. The inspected images captured by the camera are further processed with the aid of NI vision assistant software. After applying the processing function parameters provided by this software, the defect location can be clearly visualized with high precision. Three sets of defects are introduced in a Polylactide (PLA) pipe based on its position and angle along the circumference of the pipe. Further, this robot system serves as a real-time interactive image synchronization system for acquiring the inspected images. By comparing the actual and calculated defect size, the error percentage obtained was less than 5%.

Piezoelectric inertial robot for operating in small pipelines based on stick-slip mechanism:modeling and experiment

Small pipes exist in industrial and biomedical fields,and require microrobots with high operational precision and large load capacity to inspect or perform functional tasks.A piezoelectric inertial pipeline robot using a“stick-slip”mechanism was proposed to address this requirement.In this study,the driving principle of the proposed robot was analyzed,and the strategy of the design scheme was presented.A dynamics model of the stick-slip system was established by combining the dynamics model of the driving foot system and the LuGre friction model,and the simulation analysis of the effect of system parameters on the operating trajectory was performed.An experimental system was established to examine the output characteristics of the proposed robot.Experimental results show that the proposed pipeline robot with inertial stick-slip mechanism has a great load capacity of carrying 4.6 times(70 g)its own mass and high positioning accuracy.The speed of the pipeline robot can reach up to 3.5 mm/s(3 mm/s)in the forward(backward)direction,with a minimum step distance of 4µm.Its potential application for fine operation in the pipe is exhibited by a demonstration of contactless transport.