On the design of reactionless 3-DOF planar parallel mechanisms

A reactionless machine will not apply reaction forces and moments on the mounting base during motion. This article presents the theory for design of a reactionless planar parallel mechanism. The salient features of this design are: (i) it uses auxiliary parallelograms to locate the center of mass of each leg at the base, (ii) choice of geometric and inertial parameters to satisfy the reactionless conditions and/or selection of trajectory to achieve a reactionless design. We illustrate the reactionless feature of such a mechanism through computer simulations.