Abstract
In this paper, we present a new in-pipe robot with independent underactuated parallelogram crawler modules, which can automatically overcome inner obstacles in the pipes. The parallelogram crawler modules are adopted to maintain the anterior-posterior symmetry of forward and backward movements, and a simple differential mechanism based on a pair of spur gears is installed to provide underactuated mechanisms. A central base unit connects each crawler module through foldable pantograph mechanisms. In addition, an operation controller to make the robot turn is developed. To verify the basic behavior of this robot, primary experiments in a pipe with different diameters, a pipe with a partial step, bend pipe, and T-branch were conducted.
