[ Uppsala Univ. | Signals and Systems | Staff | Research | Publications | Education ]

Systematic Anti-Windup Compensator Design for Multivariable Systems

Jonas Öhr

Master Thesis, Report UPTEC 95150E, December 1995.

Report, without figures, available in Postscript : compressed(gz) 254K , uncompressed 775K.

The aim of anti-windup compensation is to modify the dynamics of a control loop when control signals saturate, so that a good transient behaviour is attained after desaturation.

Model-based anti-windup compensation is here considered for both single-input single-output (SISO) and multiple-input multiple-output (MIMO) systems.

A modified controller structure is proposed, which leaves the nominal closed-loop dynamics unchanged, as long as none of the control signals saturate. The loop gain around the saturation can be adjusted by designing a special anti-windup compensation transfer-function matrix.

Two approaches for the design of MIMO anti-windup compensation are developed. One is based on a fully crosscoupled MIMO system, whereas the other approach is applicable for control systems which utilize decoupling. Both approaches are generalizations of the systematic anti-windup design procedure developed by Sternad and Rönnbäck for scalar systems.

The main idea behind the MIMO approaches in the present report, is to reduce MIMO design to a set of scalar designs, by diagonalizing the loop gain around the control signal saturation elements. As in the scalar case, the design equations will then consist of scalar spectral factorizations. The multivariable approach is completely general and since it is based on rational fractions, it will be applicable to continuous-time systems as well as discrete-time systems. A number of examples are investigated and diffenrent design choices are evaluated.

ABB Industrial Systems, in cooperation with the Signal Processing Group under a Nutek Regina project.

Thesis Advisors:
Anders Ahlén and Mikael Sternad

Related publications:
Conference paper (ECC 1997), which presents the methodology.
Scalar case, described in a report by Rönnbäck and Sternad 1993.

Homepage ; Publications ; Staff ; Related research ; Main entry in publ. lists

webmaster@signal.uu.se   | June 11, 1997 (MS) | www.signal.uu.se/Publications/abstracts/m954.html