A Wheeled V-shaped In-Pipe Robot with Clutched Underactuated Joints

Abstract

This paper presents a wheeled V-shaped in-pipe robot in which the two outputs of the wheel shaft and roll joint are driven solely by a single actuator input. This underactuation is generated by a simple miter gear mechanism. Generally, to control two movements easily, one of the outputs of the underactuated mechanism is constrained by the resilience force of springs or by the friction force. However, this complicates the control of each output. In this study, a one-way clutch is installed to completely constrain one of the outputs (wheel movement). By using this clutch, the proposed mechanism enables a hemispherical wheel to switch between pitch and roll rotations by selecting the drive direction of a single motor. The one-way clutch constrains the wheels to rotate in only one direction. To take advantage of this constraint, the robot changes its direction of movement between forward and backward by using the rolling movement of the robot. After describing the configuration of the proposed robot and a roll-angle model of the robot, experiments are conducted in straight pipes, bending pipes, and an out-of-plane double elbow.