Bandwidth increase by shaping the plant in combination with the controller — The role of damping in positioning tables

In high tech motion systems, the finite stiffness of mechanical components usually limits the bandwidth of the control system. This can be counteracted by increasing the controller complexity. The resonance frequencies and the amount of damping of the non-rigid body dynamics significantly affect the achievable bandwidth. This paper describes a method to add damping to the flexible behavior of a motion stage, by using tuned mass-dampers with very high local damping. This results in a control bandwidth improvement of over 150%, which leads to a disturbance suppression of over 10 times for both force and displacement disturbances.