  This paper presents the design of an in-pipe climbing robot that operates
using a novel `Three-output open differential'(3-OOD) mechanism to traverse
complex networks of pipes. Conventional wheeled/tracked in-pipe climbing robots
are prone to slip and drag while traversing in pipe bends. The 3-OOD mechanism
helps in achieving the novel result of eliminating slip and drag in the robot
tracks during motion. The proposed differential realizes the functional
abilities of the traditional two-output differential, which is achieved the
first time for a differential with three outputs. The 3-OOD mechanism
mechanically modulates the track speeds of the robot based on the forces
exerted on each track inside the pipe network, by eliminating the need for any
active control. The simulation of the robot traversing in the pipe network in
different orientations and in pipe-bends without slip shows the proposed
design's effectiveness.
