Force Analysis of a Spherical Single-wheeled Robot

The spherical robot (Ballbot) is a single-wheeled robot that uses a spherical ball to move on a flat surface. So, the Ballbot is designed so that is balanced on a spherical wheel, and since the robot has only one contact point with the ground, it is considered as omnidirectional. The robot is stabilized through the ball movements, which works such as an inverted pendulum. The Ballbot is suited to interact with the human due to the appropriate height and dimension. The purpose of this article is to improve the design of a spherical single-wheeled robot by force analysis. The stability of the robot on the ball is one of the most important challenges for this robot. In this article, after discussing introduction on wheeled robots, the types of spherical single-wheeled robots are presented. Specifications and design tips for the spherical single-wheeled robots are considered and the dynamic equations of the robot are presented. Therefore, various parts of the robot are investigated as a mechatronic system including electronics, mechanics and controls. In order to control the robot, the controller has been implemented. After design review, simulation of a spherical single-wheeled spherical robot and its force analysis in MSC ADAMS and Matlab software are presented. By examining the contact forces in the simulator, design details have been investigated. Finally, stabilization of the presented Ballbot is discussed.