V-shift control for snake robot moving the inside of a pipe with helical rolling motion

A snake robot would be applied to a machine that goes into a narrow space to investigate the inside of a structure. Recently, multiple locomotion modes of snake robots have been realized. In the previous study, we also achieved some kind of locomotion modes such as undulatory locomotion mode, sidewinding locomotion mode, lateral rolling locomotion mode and helical rolling locomotion mode to move along a pipe. The shape of the robot in each locomotion mode is calculated by using mathematical continuum curve model respectively. However, it is necessary to change these shape smoothly when the environment where the snake robot is moving changes. It is relatively easy to achieve this in the case that the snake robot moves along its body, namely it moves to a tangential direction, by using the traditional shift control. In this paper, we propose a s-shift control and a v-shift control for a snake robot moving vertical direction to its body. In this paper, the v-shift control is installed to an experimental snake robot and the locomotion performance of robot is evaluated for the pipe composed of a straight pipe and an elbow pipe. As a result, the snake robot could successfully changes its locomotion mode to move the inside of the pipes with two types of helical rolling motion.