Kinematic modeling and redundancy resolution for nonholonomic mobile manipulators

We consider robotic systems made of a nonholonomic mobile platform carrying a manipulator (nonholonomic mobile manipulator, NMM). By combining the manipulator differential kinematics with the admissible differential motion of the platform, a simple and general kinematic model for NMMs is derived. Assuming that the robotic system is kinematically redundant for a given task, we present the extension of redundancy resolution schemes originally developed for standard manipulators, in particular the Projected Gradient (PG) and the Reduced Gradient (RG) optimization-based methods. The case of a configuration-dependent task specification is also discussed. The proposed modeling approach is illustrated with reference to representative NMMs, and the performance of the PG and RG methods for redundancy resolution is compared on a series of numerical case studies.