Uppsala universitet

A Novel Derivation Methodology for Polynomial-LQ Controller Desing

Mikael Sternad and Anders Ahlén

IEEE Transactions on Automatic Control ,
vol 38, pp 116-121, January 1993. © 1993 IEEE.
Also: Internal Report UPTEC 90058R, Dept. of Technology, Uppsala University.

Report version available in Pdf

A simple derivation methodology for optimization of linear quadratic controllers is presented, in the discrete time polynomial systems framework. A control law variation, regarded as a potential feedforward from the innovations, is used. Orthogonality is evaluated in the frequency domain, by collectively cancelling unstable poles by zeros.

The suggested method, summarized as a three-step scheme, is exemplified on a disturbance measurement feedforward and a multivariable LQG output feedback problem. It is a simple and more direct alternative to the ``completing the squares'' approach.

Related publications:
Book chapter with more discussion on feedforward design based on marginally stable models.
Paper in IEEE Trans. SP 1991, where the corresponding method is applied to filter design.
PhD Thesis by K Öhrn, where the method is used for robust LQ feedforward control.

| Research on polynomial methods | Main entry in list of publications |
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