Partial Shaking Force Balancing of 3-RRR Parallel Manipulators by Optimal Acceleration Control of the Total Center of Mass

Abstract

This paper deals with the problem of shaking forces balancing of 3-RRR planar parallel manipulators. It is known that this problem can be solved by optimal mass redistributions of the moving links, i.e. by adding counterweights or auxiliary structures. In this paper, the reduction of shaking forces of 3-RRR planar parallel manipulators is accomplished by the optimal trajectory planning of the common center of mass of the manipulator, which is carried out by “bang-bang” profile. Such a method allows a considerable reduction in shaking forces without adding any counterweight. Using such a solution, the disadvantages of adding counterweights have been avoided. An increase in the mass of moving links usually leads to an increase in shaking moments and input torques. It has been shown via numerical simulations that the use of the “bang-bang” profile is a more efficient not only for shaking forces minimization but also for minimization of shaking moments and input torques. The efficiency of the suggested balancing approach is illustrated by numerical simulations carried out via ADAMS software.