Compensation of mode shapes with a piezo electric actuator for an optical drive

In miniaturized systems (e.g. optical disk drives) much effortis made to design a structure in such a way that the demandson dimensions (height, width) and desired bandwidthare satisfied. Easier, and often cheaper designs can not beused, because they suffer from lower resonance frequencies,which limit the bandwidth. A method is presented formechatronic structures that compensates unwanted bandwidthlimiting resonance frequencies with an additionalpiezo electric actuator. Advantage of this method is thatno extra sensor is used and that the contribution of the piezois much easier to tune (when compared to a notch filter),since it is part of the structure. Disadvantage is that thepiezo influences the dynamics of the original system, whichcomplicates the choice of a suitable piezo actuator

Modellering en regelontwerp van het warm proces van een kopieerapparaat

Confidential

Self-tuning in master-slave synchronization of high-precision stage systems

For synchronization of high-precision stage systems, in particular the synchronization between a wafer and a reticle stage system of a wafer scanner, a master–slave controller design is presented. The design consists of a synchronization controller based on FIR filters and a data-driven self-tuning approach is used to find the coefficients of these filters. In the context of Lur'e systems, i.e. the reticle stage slave system has a variable gain controller with saturation nonlinearity, a part of the gradients needed for self-tuning is obtained from reconstruction using closed-loop nonlinear models. The remaining part is given by sampled data obtained primarily from time-series measurements. Performance with the synchronization controller is shown to be bounded by a waterbed effect: low-frequency suppression comes at the price of high-frequency amplification. For the considered Lur'e stage systems the ability of the self-tuning to induce improved tracking is discussed in view of this waterbed effect for either simulation results or experimental results

Introduction to an integrated design for motion systems using over-actuation

In this paper an introduction and motivation is given towards an integrated design approach for motion systems using overactuation. Looking to motion systems and their history, the current status of mechatronic motion systems is discussed. One of the main aspects that limit performance in mechanical systems is the presence of vibrations. An overview is presented of several passive and active methods to solve vibration problems. Active vibration control can be regarded as a form of overactuation to improve system performance. It is expected that an integrated overactuated design approach will be advantageous over traditional vibration control solutions, which often make use of adaptations after the mechanical design has been completed. Before a framework for an integrated design approach can be posed, different strategies of overactuation must be investigated. To study the closed-loop characteristics of resonances in mechanical systems with more actuators more closely, some first explorations of a dual-input single-output motion system are made

Modal framework for closed-loop analysis of over-actuated motion systems

A large class of motion systems used in precision applications is required to meet increasing levels of tracking performance whereas costs should not rise drastically. Allowing for more actuators and sensors than rigid-body modes, which is called over-actuation, higher levels of performance can be obtained without increasing mechanical stiffness. However, the designof MIMO controllers for motion systems is not straightforward and a better understanding of the modal behavior in closed-loop would be valuable. In this paper we introduce a new framework to analyze multivariable controllers for over-actuated motionsystems in modal form. This approach enables us to analyze various closed-loop properties, such as modal tracking behavior and modal disturbance attenuation. Both feedback and feedforward performance is evaluated at the same time, using a global performance measure. The analysis is illustrated by an example

Overactuated feedback control using a decoupling approach

Abstract only