Experimental Verification of Vibration Absorbers Combined with Input Shaping for Oscillatory Systems

Systems that exhibit flexible dynamics are susceptible to vibration caused by changes in the reference command and from external disturbances. Feedback control is an obvious choice to deal with these vibrations, but in many cases, it is insufficient or difficult to implement. Input shaping does not deal with vibration excited by external disturbances; however it has proven beneficial for reducing vibration that is caused by changes in the reference command. On the other hand, vibration absorbers have long been used to decrease vibration from external sources, particularly sinusoidal disturbances. Vibration absorbers can also be designed to reduce vibration from a known trajectory move, such as a step motion. To improve overall performance, a vibration absorber and input shaping scheme are designed to reduce vibration from step disturbances from both the reference command and external sources. The usefulness of this combined approach is demonstrated through experimental tests on a linear motor driven stage.