Drive train design of redundant-drive backlash-free robotic mechanisms

This paper describes a systematic methodology for the drive train design of redundant-drive backlash-free robotic mechanisms (RBR mechanisms). A two-stage procedure that involves the selection of drive train configurations and the determination of gear ratios is presented. It is shown that proper gear train configurations associated with the inner structure matrix can be determined by the given inertia characteristics of primary links, while those associated with the outer structure matrix can be determined from the unidirectional drive characteristics of the RBR mechanism. Conditions determining gear ratios such that the RBR mechanism can have optimum dynamic performance are also derived. From the selected gearing configuration’s and determined gear ratios, the locations of motors and arrangements of drive trains can be laid out accordingly. A 3-dof RBR mechanism is used as an illustrative example.