Design of back-drivable joint mechanism for in-pipe robot

In this paper, a back-drivable joint mechanism for an in-pipe robot is presented. The joint mechanism consists of 2-pitch and 1-roll joint. The back-drivability of the joint mechanism is realized by using a ball-screw and a steel wire rope. When the in-pipe robot with the back-drivable joint mechanism passes through pipeline elements except the miter and the branch, the control of the joint mechanism is not required. In addition, a rescue mechanism is not needed in case of emergency such as the loss of power, communication and control. Besides, the 2-pitch joint of this joint module assists the in-pipe robot to pass through the miter and the branch safely and quickly. Finally, the performance of back-drivable joint module is experimentally validated.