Broadband damping of non-rigid-body resonances of planar positioning stages by tuned mass dampers

In high tech motion systems, the finite stiffness of mechanical components often limits the bandwidth of the control system. This is usually counteracted by increasing the controller complexity, for instance by adding notch filters. The height of the resonance frequencies of the non-rigid body dynamics and the amount of damping 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 an over-critical damping value in contrast to a regular TMD with 10–20% damping. This over-critical damping results in a robust damper mechanism which is insensitive for parameter variations in terms of stiffness and damping. The main result is a significant modal damping increase over a broad band of resonant frequencies, with only four dampers added. This results in a bandwidth improvement of over 150% in z-direction, which leads to a disturbance suppression of over 10 times for both force and displacement disturbances. A damper test setup has been realized and tested to validate the possibility to create dampers with this over-critical damping behavior.