Minimization of Inertial Loads in Planar Parallel Structure Manipulators by Means of Optimal Control

Abstract

A combined method for balancing of planar parallel structure mechanisms including a synthesis of mechanisms with decreased acceleration of the mass center and also balancing by redistributing the masses of moving links is presented in this study. This method is implemented in two stages: (1) optimal redistribution of the driving link masses for securing convergence of the gripping trajectory and the total mass center of the manipulator; (2) development of optimal control of grip acceleration according to the “bang-bang” law. Such control makes it possible to maximally decrease the acceleration of the mass center and the resultant vector of inertial forces. The method is applied to the planar 5R and 3RRR parallel structure manipulators. The efficiency of the method is illustrated by numerical simulations using the software ADAMS, where the inertial loads acting on the 5R manipulator’s base are decreased by 78% and those on the 3RRR manipulator’s base, by 60%.