Abstract
Hybrid-chain manipulators consisting of serial branches acting in parallel on a common end effector are examined. All non-redundant, six DOF hybrid manipulator structures are enumerated and a specific hybrid-chain structure is chosen as most promising based upon performance considerations. A class of kinematically simple (KS) serial-chain branches suitable for the chosen hybrid structure is defined. Arguments based upon kinematic equivalency of the branches and mobility of the assembled hybrid chain are used to show that there exist only five unique branch structures belonging to the KS class. It is demonstrated that the solution to the inverse displacement problem for hybrid structures based on the KS branches can be expressed in a closed form. Furthermore, the KS based hybrid-chains are shown to belong to a family of manipulator structures whose forward displacement solutions can be resolved through roots of a 16th order polynomial.
