Optimal Configuration Selection for a Cooperating System of Mobile Manipulators

In this paper, we examine the design and selection of optimal configuration of a system of multiple, wheeled mobile manipulators that can team up to cooperatively transport a large common object. Each individually autonomous mobile manipulator consists of a differentially driven wheeled mobile robot (WMR) with a passive, two degree-of-freedom (d.o.f), planar revolute-jointed arm mounted in the plane parallel to the base. The composite multi-degree-of-freedom vehicle, formed by placing a common object on the end-effector of two (or more) such mobile manipulator systems, possesses the ability to change its relative configuration as well as accommodate relative positioning errors of the mobile bases. However, the combination of the non-holonomic constraints of the wheeled mobile bases, the presence of passive joints and closed kinematic loops of the articulations require a careful treatment. The suitable selection of the dimensions of the intermediate linkage and the overall configuration is critical to enhancing the overall performance. In this paper we will focus our attention on the formulation of a design-optimization problem to aid the selection of the configuration of the composite vehicle to attain near-isotropic manipulability of the common object.