Mlg Matthijs Boerlage

Model-based feedforward for motion systems

This paper considers model-based feedforward for motion systems. The proposed feedforward controller consists of an acceleration feedforward part and an inverse dynamics model of flexible modes. Based on analysis and H/sub /spl infin// model-based feedforward design, the inverse dynamics can be restricted to a second order filter in the form of a skew notch even if the motion system has more parasitic modes. The benefit of this is an on-line tuning possibility. Tracking errors and settling times can be reduced significantly compared to acceleration feedforward.

MIMO jerk derivative feedforward for motion systems

This paper shows that flexible modes in motion systems result in residual dynamics that can not be reduced using conventional acceleration feedforward and static decoupling. When reference trajectories with low frequency excitation are applied, low frequency tracking errors and cross-talk errors occur as peaks during jerk phases of a motion. A multivariate jerk derivative feedforward controller is presented which compensates for the joint contribution of all flexible modes in the low frequency region. Furthermore it is shown that no higher order (than 4) feedforward controller is required to improve low frequency tracking performance. A simulation example of a positioning device shows a significant improvement of the tracking performance

Control Relevant Blind Identification of Disturbances With Application to a Multivariable Active Vibration Isolation Platform

This paper deals with the identification of root causes of disturbances in multivariable systems. It is shown that this boils down to a blind identification problem that can be solved, under additional assumptions, within certain indeterminacies. Using the results from identification, it is illustrated how sources can be physically interpreted and the location of the sources can be recovered. Also, a design tool is developed to select multivariable feedback controller candidates. The practical feasibility is demonstrated on an industrial multivariable controlled active vibration isolation platform.

Frequency response based multivariable control design for motion systems

In this paper, we discuss the design of multivariable motion controllers exploiting crosscouplings in the controller for open loop decoupling, disturbance rejection and feedforward decoupling. Using specific properties of motion systems, we illustrate that frequency response design methods can be extended to handle several multivariable control problems. Application to high performance motion systems shows significant improvement

Multivariable control design for fixed direction disturbances

In this paper, a blind identification method is employed to model multivariable disturbances with fixed direction. The multivariable disturbance model is used to design non- diagonal weighting filters for Hinfin control. It is demonstrated that in this way, intuitive shaping of the directions of closed loop transfer functions is facilitated, maximally exploiting design freedom that has no analogue for scalar systems.

Blind identification and allocation of multivariate disturbances

A second order statistics based blind identification technique is used to recover the physical sources from disturbances acting on a multivariable system. The results are then used to find the physical location of disturbance sources in an active vibration isolation platform. Furthermore, implications for multivariable controller design are discussed.