Walking model and planning algorithm of the over-obstacle pipe climbing robot

Effective inspection of pipelines is of significant importance in the industry. In order to reduce human labour, risk and expenses in this area, robots can be applied. The pipe robot should perform not only the linear motion in the axial direction but also the rotary motion in the circumferential direction while working. Meanwhile, in order to achieve reasonable performance and efficiency, these robots should have high enough normal linear motion velocity. They should be able to cross a pipe in one direction to another pipe in a different direction to achieve the over-obstacle function. In this study, a double-joint wheeled robot model is established to fulfil the actions of fast walking, rotation around the pipe and over-obstacle on spatial pipes. Based on the expected position on the pipe for the robot constructed by the proposed model, the precise starting position and control synthesis of the axial and circumferential velocities are initially determined. In order to study the velocity synthesis more accurately, the pipe is unfolded along the axial direction to transform the spatial motion into a plane motion. A novel spatial distribution form of driving wheels is proposed. In addition, based on the initial position of the straight, T-shaped, L-shaped, two-axis ‘+’-shaped and spatial three-axis ‘+’-shaped pipes, the posture adjustment of the robot prior, during and after the over-obstacle is investigated. Furthermore, the corresponding planning algorithms are established.