Design of Vibration Absorbers for Step Motions and Step Disturbances

Mechanical systems with flexible dynamics often suffer from vibration induced by changes in the reference command or from external disturbances. The technique of adding a vibration absorber has proven useful at eliminating vibrations from external disturbances and rotational imbalances. Traditionally, vibration absorbers have been designed for systems subject to sinusoidal or random excitations. Here the applicability of vibration absorbers to systems with steplike changes in the reference command or similar disturbances is studied. This type of motion is more common in robotic applications. Here absorbers are designed using two methods; the first technique uses a weighting on peak overshoot and settling time to allow tradeoffs between the two performance criteria. The second simpler method utilizes an eigenvalue technique to predict the time constant. Both of these techniques provide the possibility of significant improvement in settling time. The performance of this absorber design strategies is compared with previously proposed vibration absorbers and experimental results verify its utility.