on the in-pipe inspection robots traversing through elbows

a general robotic mechanism was presented for in-pipe inspection oflevel pipes with varied diameter or curved pipelines. the robot employed three legs comprised of parallelogram linkages mechanism which enables adapting to various elbow joints in the piping systems. the curvatures in pipeline are the most important constraints in front of the robot through navigation process. to study the adaptability of in-pipe robots to the elbow, geometrical analysis was used to determine the minimum required diameter of an assumed resizable cylinder when it traverses through elbows. the contact points of the cylinder and the elbow are located at the medial longitudinal cross section of the elbow. however, for any designed configuration of the robots, the contact points are located at other longitudinal cross sections. for any elbow joint, a 3d space, so-called “curved pipe limited area” was defined using the minimum required width along all longitudinal cross sections in elbows. the traversing robot should be adaptable to this limited area which is a function of robot’s length, pipes’ diameter and radius of curvature. a set of computer simulation was used to verify the derived analytical equations. the verified equations in this paper enable designers to confirm the dimensions of the robots for guaranteed traversing through standard elbows in pipeline. in addition to optimizing the robot’s dimensions in designing process, the proposed equations can be used for active controlling of robot’s diameter when it traverses through elbows.