A screw-based dynamic balancing approach, applied to a 5-bar mechanism

Dynamic balancing aims to reduce or eliminate the shaking base reaction forces and moments of mechanisms, in order to minimize vibration and wear. The derivation of the dynamic balance conditions requires significant algebraic effort, even for simple mechanisms. In this study, a screw-based balancing methodology is proposed and applied to a 5-bar mechanism. The method relies on four steps: 1) representation of the links’ inertias into point masses, 2) finding the conditions for these point masses which result in dynamic balance in one given pose (instantaneous balance), 3) extending these conditions over the workspace to achieve global balance, 4) converting the point mass representation back to feasible inertias. These four steps are applied to a 5-bar mechanism in order to obtain the conditions which ensure complete force balance and additional moment balance over multiple trajectories. Using this methodology, six out of the eight balancing conditions are found directly from the momentum equations.