Development of a Spherical Shell Robot with Rolling and Legged Locomotion

Herein, we propose a spherical shell robot that can roll and move on its legs, and develop a prototype of the robot. Recently, there has been a growing demand for robots that can move freely and gather information on rough terrains, such as disaster sites, which are not ac-cessible to humans. The robot developed here has two types of mobilities: rolling movement using a spherical shape and walking movement using its legs. Because the morphological transformation does not require re-combination of parts, it can be reversibly performed via remote control. Therefore, the robot can select the movement method according to the environment, and reach the target point reliably even on uneven terrains, such as a disaster site. We designed a mechanism that enabled the transformation of the form and devised an operation method. Accordingly, a prototype was developed and tested. A rolling test on flat ground confirmed that the robot can roll over 5.0 m and its speed could be controlled using a gyro sensor. The leg locomotion test confirmed that the robot can turn and move straight ahead without turning over. In addition, we also conducted experiments, such as sudden stops and remote morphological deformation, to confirm the operation of the robot during rolling.