This paper investigates the optimal isotropic characteristics of a caster wheeled omnidirectional mobile robot under full actuation. First, with the characteristic length introduced, the kinematic model is obtained based on the velocity decomposition. Second, the algebraic conditions for the isotropy are derived, from which two isotropic configurations are identified along with the required isotropic characteristic length. Third, the local and the global isotropy indices are examined to determine the locally and the globally optimal characteristic lengths. Finally, with prior knowledge of the isotropic configurations, the problem of determining the optimal initial configuration of a moving COMR is discussed

The omnidirectional mobility of a mobile robot loses significance in motion control, unless the isotropy characteristics of the mechanism is maintained well. This paper investigates the local and global isotropy of an omnidirectional mobile robot with three caster wheels. All possible actuations with different number and combination of rotating and steering joints are considered. First, the kinematic model based on velocity decomposition and the algebraic conditions for the local isotropy are obtained. Second, the geometric conditions for the local isotropy are derived and all isotropic configurations are fully identified. Third, the global isotropy index is examined to determine the optimal parameters in terms of actuation set, characteristic length, and steering link length.