Multivariable disturbance modelling for web processes

Abstract

This paper considers suitable disturbance models for use in the design of control systems for web forming processes. It suggests a practical disturbance representation and, using spectral factorization, presents a multivariable aggregated model of the disturbance.The paper compares generalized minimum variance (GMV ) controllers designed using uncorrelated and correlated disturbance models and demonstrates the improvement in performance of a multivariable GMV controller which is designed to accommodate the cross direction correlation in the disturbance compared to the GMV controller that is commonly used in practice, which is based on a model that ignores the e ects of correlated disturbances.

Discrete-time anti-windup compensation for synchrotron electron beam controllers with rate constrained actuators

“…The open loop behaviour of the position of an electron beam in a synchrotron is well approximated by [Duncan, 2007, Gayadeen, 2014…”

“…A key property of the process is that all the actuators have the same dynamics but have different steady state responses, so that the process is described by simple dynamics but a generally ill-conditioned steady state matrix. Following the approach of cross-directional control systems which generally exhibit these properties [Corscadden and Duncan, 2000, Duncan and Bryant, 1997, Featherstone et al, 2000, Heath, 1996, the steady state matrix is decomposed using orthogonal basis functions to identify and decouple the controllable modes of the system. This decomposition of the steady state response matrix allows controller dynamics for individual modes to be designed independently and simplifies tuning of the large-scale multivariable controller.…”

“…This decomposition of the steady state response matrix allows controller dynamics for individual modes to be designed independently and simplifies tuning of the large-scale multivariable controller. For the Diamond Light Source system, an Internal Model Control (IMC) approach is used to select the controller dynamics for each mode because of the simplicity of tuning for performance and robustness since the process dynamics are inherently stable [Duncan, 2007, Gayadeen and Duncan, 2012, 2014,.…”

The Impact of Variable Wind Shear Coefficients on Risk Reduction of Wind Energy Projects

“…The evaluation of wind speed and wind shear is also inherently linked to control systems as such information is a prerequisite in the development of predictive control methodologies. The multivariable temporal variations in wind shear could be addressed using control theory and represented as a multivariable disturbance model, which has been demonstrated in other industries to result in improved controller performance [37]. This along and hybrid forecasting are emerging research opportunities [38].…”

Case studies in Bayesian segmentation applied to CD control

“…A time series of iid z error vectors e t and transfer function G x ðq À1 Þ form the disturbance model. G x ðq À1 Þ is not commonly used in controller design, although a reasonable model for this process is discussed in Reference [27] which allows for random variation and an occasional step. The mean value of the distribution which generates e t is usually non-zero and this is denoted m CD :…”