Design and Development of a Wall-Pressed Robot for In-Pipe Inspection

Pipelines have become a major part of energy infrastructure, which requires a secure and reliable means of maintenance. It has become critical to introduce advanced robotic methods for inspecting pipelines in order to offer a more secure alternative to human entry and facilitate deployment of specialized visual inspection devices. This paper primarily deals with the design and development of a simple wall-pressed robot capable of detecting visual defects inside pipelines of diameters ranging from 38 cm to 65 cm. The overall structure of the robot is divided into two segments, each equipped with a three-wheel module arranged 120° from the central axis. Static structural analysis for strength optimization is performed using finite element method. Poly lactic acid plastic and aluminium alloy are selected as structural materials for lightweight design. Real time forces on the robot structure are simulated by applying fixed supports at the holding frame, – 33.85 N compressive forces at the wheel ends of the linkage in the axial direction and placing 145 gm weight at the motor linkage. Motion simulations are carried out to study functionality of driving mechanism. A robot prototype is built and powered by 11.1 V 5200 mAh LiPo batteries. Experimental testing is conducted in a steel pipe of inner diameter 38 cm to validate the robot’s design, assessing traction, gradeability and operational robustness. Testing results are validated with calculated results that the robot applied a tractive force of 26.26 N to the in-pipe wall against each wheel during normal operation and maintained a uniform velocity of 30 mm/sec in horizontal test. This robot has the potential to ensure the safety, reliability and affordability of operations in oil and gas pipelines.