Design of a four-wheeled omnidirectional mobile robot with variable wheel arrangement mechanism

An omnidirectional mobile robot equipped with four independent omnidirectional wheels can perform 3 DOF motion and has one redundant DOF. This redundancy can be used to drive the mechanism enabling the wheel arrangement to vary, which can function as a continuously-variable transmission (CVT). In this research, a special mechanism called a variable wheel arrangement mechanism is proposed to increase the range of velocity ratio for the CVT from the wheel velocities to robot velocity, which may improve performance of the mobile robot. A mobile robot with this mechanism was constructed and various tests have been conducted to demonstrate the validity and feasibility of the proposed mechanism.