A Comparison of the Performance Improvement by Collocated and Noncollocated Active Damping in Motion Systems

In this paper, both collocated and noncollocated active vibration control (AVC) of a the vibrations in a motion system are considered. Pole-zero plots of both the AVC loop and the motion-control (MC) loop are used to analyze the effect of the applied active damping on the system dynamics. Using these plots and the simulated end-effector position of the actively damped plant, a comparison is made between the collocated AVC, using Integral Force Feedback (IFF), and noncollocated AVC, by means of acceleration feedback. It is demonstrated that collocated AVC improves the performance of the plant by adding damping to both the resonance and anti-resonance mode of the plant and making it possible to increase the motion-control bandwidth. The applied noncollocated AVC improves the performance by adding damping to the resonance mode. However, as opposed to the collocated AVC, for the applied noncollocated AVC, there is a trade-off between various performance criteria, such as rise time and settling time, that is determined by the balance between the added damping and the increase of the bandwidth. This is true for all the AVC methods that do not increase the damping of the anti-resonance mode.