Active Damping of Vibrations in High-Precision Motion Systems

Technology advancements feed the need for ever faster and more accurate industrial machines. Vibration is a significant source of inaccuracy of such machines. A light-weight design in favor of the speed, and avoiding the use of energy-dissipating materials from the structure to omit any source of inaccuracy, contribute to a low structural damping. The goal of this research is to investigate the addition of damping to the rotational vibration mode of a linearly actuated motion system to •achieve a shorter settling time in the transient response of the plant to a commanded motion •increase the achievable closed-loop motion-control bandwidth This thesis starts by showing the influence of damping on the stability of motion systems, for P(I)D-type motion controllers. Furthermore, a set of guidelines is presented that can be used for a mechatronic design of an active-damping loop. It is shown that collocated active damping increases the damping of both the poles and the zeros of the motion-control loop. This allows for a higher increase of motion-control bandwidth than when the same actuator is used in both the motion-control loop and the active-damping loop. The chosen control algorithm for collocated active damping is integral force feedback. This combination results in a robustly stable closed-loop system. The effect of active damping on the end-effector dynamics of a motion system is analyzed extensively in simulation. The performance improvement by damping in the transient behavior of the plant is shown using a test setup that suffers from a rotational vibration mode.