Isotropy analysis of caster wheeled omnidirectional mobile robot

This paper presents a complete isotropy analysis of an omnidirectional mobile robot with three caster wheels. All possible actuation sets with different number and combination of rotating and steering joints are considered. First, the kinematic model of a caster wheeled omnidirectional mobile robot (COMR) having n (3 ≤ n ≤ 6) actuated joints is obtained without matrix inversion. Second, with the characteristic length introduced, the isotropy conditions of a COMR are derived, which are imposed on two Jacobian matrices. Under the isotropy condition on one Jacobian matrix, three caster wheels should be identical with the length of the steering link equal to the radius of the wheel. Third, depending on the selection of actuated joints, the isotropy conditions on the other Jacobian matrix are examined. The isotropic configurations of a COMR are identified, along with the isotropy loci in the configuration space.