MOSTS: a mobile robot with a spherical continuously variable transmission

Abstract

Introduces the design and analysis of a type of wheeled mobile robot that uses a spherical continuously variable transmission (S-CVT) element. The S-CVT is composed of a sphere, input and output discs, and variators, and power transmission is based on the friction force between the discs and the sphere. Use of the S-CVT allows for smooth operation of the mobile robot over all phases of forward, neutral, and reverse motion without the use of any brakes or clutches. The S-CVT also permits the motors to operate in their most power-efficient regimes. Motion in the plane, including pure rotation about its center is achieved by a novel pivoting device that eliminates the need for an actuated steering wheel, or an additional motor for differentiating the wheel velocities. We describe the conceptual principle behind our CVT-based mobile robot, and present a complete design and analysis of its capabilities based on a prototype currently under construction.