The Combined Use of Input Shaping and Nonlinear Vibration Absorbers

Abstract

Systems that exhibit flexible dynamics are susceptible to vibration caused by changes in the reference command, as well as, from external disturbances. Feedback control is an obvious choice to deal with these vibrations, but in many cases it is insufficient. Input shaping has proven very beneficial for reducing vibration that is caused by changes in the reference command. However, input shaping does not deal with vibration induced by external disturbances. On the other hand, vibration absorbers are an open-loop method that have long been used to decrease vibration from external sources, particularly sinusoidal disturbances. In this paper, non linear vibration absorbers are designed to reduce vibration from step disturbances. Furthermore, input shaping is combined with the absorbers in order to deal with the vibration induced by the reference command. The usefulness of this combined approach for dealing with both external and reference command disturbances is demonstrated with computer simulations.