Vertical Bend and T-branch Travels of an Articulated Wheeled In-pipe Inspection Robot by Combining Its Joint Angle and Torque Controls

The paper reports the performance verification of vertical bend and T-branch travels of an articulated wheeled in-pipe inspection robot. The robot is composed of only a single active compliant middle joint, two passive compliant joints, three drive wheels, and two roll wheels. The passage of the bend pipe is achieved only by the joint torque control, while the T-branch travel is achieved by controlling both joint angle and torque. Instead of using a torque sensor, a polyurethane-based series elastic actuator (SEA) is installed in the middle joint. In this paper, the travel performances of our developed in-pipe robot were tested on bend pipes and 10 types of T-branch with different gravity directions. From the experiments, in all cases, the effectiveness of the bend and T-branch travels performance was confirmed.