Elastodynamic effects of mass-balancing: experimental investigation of a four-bar linkage

This paper deals with static balancing of closed-loop mechanisms. The long-term goal of the research is enhancing the performance of parallel robots by means of effective static balancing strategies that take into account the system dynamic behaviour. In this contribution, the influence of mass-balancing on the elastodynamic performance of a four-bar linkage, intended as the simplest example of closed-loop mechanism, is experimentally investigated. The design of the experimental apparatus is discussed and the results of tests on both an unbalanced linkage and its balanced variant are presented. Base-transmitted forces and vibrations are monitored for constant-speed operations and for velocity ramp tests in order to characterize the elastodynamic behaviour of the linkages. The analysis is supported by implementing a flexible multibody model of the experimental apparatus that enhances the interpretation of the experimental data.