From: <par...@us...> - 2011-12-27 20:42:01
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Revision: 9470 http://octave.svn.sourceforge.net/octave/?rev=9470&view=rev Author: paramaniac Date: 2011-12-27 20:41:54 +0000 (Tue, 27 Dec 2011) Log Message: ----------- control-devel: doc fixes Modified Paths: -------------- trunk/octave-forge/extra/control-devel/inst/bstmodred.m trunk/octave-forge/extra/control-devel/inst/btamodred.m trunk/octave-forge/extra/control-devel/inst/cfconred.m trunk/octave-forge/extra/control-devel/inst/fwcfconred.m trunk/octave-forge/extra/control-devel/inst/hnamodred.m trunk/octave-forge/extra/control-devel/inst/spamodred.m Modified: trunk/octave-forge/extra/control-devel/inst/bstmodred.m =================================================================== --- trunk/octave-forge/extra/control-devel/inst/bstmodred.m 2011-12-26 21:00:43 UTC (rev 9469) +++ trunk/octave-forge/extra/control-devel/inst/bstmodred.m 2011-12-27 20:41:54 UTC (rev 9470) @@ -23,89 +23,25 @@ ## ## Model order reduction by Balanced Stochastic Truncation (BST) method. ## The aim of model reduction is to find an LTI system @var{Gr} of order -## @var{nr} (nr << n) such that the input-output behaviour of @var{Gr} +## @var{nr} (nr < n) such that the input-output behaviour of @var{Gr} ## approximates the one from original system @var{G}. -## This is motivated by the relation +## +## BST is a relative error method which tries to minimize ## @iftex ## @tex -## $$ || y - y_r ||_2 = || G - G_r ||_{\\infty} \\ || u ||_2 $$ +## $$ || G^{-1} (G-G_r) ||_{\\infty} = min $$ ## @end tex ## @end iftex ## @ifnottex ## @example -## ||y-yr|| = ||G-Gr|| ||u|| -## 2 inf 2 +## -1 +## ||G (G-Gr)|| = min +## inf ## @end example ## @end ifnottex ## -## BST is a relative error method which tries to minimize -## @iftex -## @math{|| \\Delta_r ||,} -## @end iftex -## @ifnottex -## Deltar, -## @end ifnottex -## where -## @iftex -## @math{\\Delta_r} -## @end iftex -## @ifnottex -## Deltar -## @end ifnottex -## is implicitly defined by -## @iftex -## @math{G - G_r = \\Delta_r \\ G.} -## @end iftex -## @ifnottex -## G-Gr = Deltar*G. -## @end ifnottex -## For the H-infinity norm, the best approximation problem is -## unsolved so far. Nevertheless, balanced truncation and related -## methods can be used to obtain good approximations using this measure. ## -## Available approximation methods are the accuracy-enhancing square-root (SR) -## or the balancing-free square-root (BFSR) versions of -## the Balance & Truncate (BTA) or Singular Perturbation Approximation (SPA) -## model reduction methods for the ALPHA-stable part of the system. ## -## Unstable models are handled by separating the stable and unstable -## parts additively, applying the model reduction only to the stable -## part and by joining the reduced stable with the original unstable part. -## The order of the reduced system can be selected by the user or -## can be determined automatically on the basis of the computed -## Hankel singular values. -## -## For MIMO models, proper scaling of input-output channels is of -## utmost importance. This can @strong{not} be done by the equilibration -## option or the @command{prescale} command because these perform state -## transformations only. While enhancing numerics, state transformations -## have no influence on the input-output behaviour and the magnitude of -## the corresponding signals. Since the algorithm calculates the -## H-infinity norm of these signals, important behaviour of @var{G} -## could be neglected just because the corresponding signals have smaller -## numbers than those of other, less important effects of @var{G}. -## -## BST is often suitable to perform model reduction in order to obtain -## low order design models for controller synthesis. -## -## Approximation Properties: -## @itemize @bullet -## @item -## Guaranteed stability of reduced models -## @item -## Approximates simultaneously gain and phase -## @item -## Preserves non-minimum phase zeros -## @item -## Guaranteed a priori error bound -## @iftex -## @tex -## $$ || G^{-1} (G-G_r) ||_{\\infty} \\leq 2 \\sum_{j=r+1}^{n} \\frac{1+\\sigma_j}{1-\\sigma_j} - 1 $$ -## @end tex -## @end iftex -## @end itemize -## -## ## @strong{Inputs} ## @table @var ## @item G @@ -218,6 +154,53 @@ ## false if @code{G.scaled == true}. ## @end table ## +## +## For the H-infinity norm, the best approximation problem is +## unsolved so far. Nevertheless, balanced truncation and related +## methods can be used to obtain good approximations using this measure. +## +## Available approximation methods are the accuracy-enhancing square-root (SR) +## or the balancing-free square-root (BFSR) versions of +## the Balance & Truncate (BTA) or Singular Perturbation Approximation (SPA) +## model reduction methods for the ALPHA-stable part of the system. +## +## Unstable models are handled by separating the stable and unstable +## parts additively, applying the model reduction only to the stable +## part and by joining the reduced stable with the original unstable part. +## The order of the reduced system can be selected by the user or +## can be determined automatically on the basis of the computed +## Hankel singular values. +## +## For MIMO models, proper scaling of input-output channels is of +## utmost importance. This can @strong{not} be done by the equilibration +## option or the @command{prescale} command because these perform state +## transformations only. While enhancing numerics, state transformations +## have no influence on the input-output behaviour and the magnitude of +## the corresponding signals. Since the algorithm calculates the +## H-infinity norm of these signals, important behaviour of @var{G} +## could be neglected just because the corresponding signals have smaller +## numbers than those of other, less important effects of @var{G}. +## +## BST is often suitable to perform model reduction in order to obtain +## low order design models for controller synthesis. +## +## Approximation Properties: +## @itemize @bullet +## @item +## Guaranteed stability of reduced models +## @item +## Approximates simultaneously gain and phase +## @item +## Preserves non-minimum phase zeros +## @item +## Guaranteed a priori error bound +## @iftex +## @tex +## $$ || G^{-1} (G-G_r) ||_{\\infty} \\leq 2 \\sum_{j=r+1}^{n} \\frac{1+\\sigma_j}{1-\\sigma_j} - 1 $$ +## @end tex +## @end iftex +## @end itemize +## ## @strong{Algorithm}@* ## Uses SLICOT AB09HD by courtesy of ## @uref{http://www.slicot.org, NICONET e.V.} Modified: trunk/octave-forge/extra/control-devel/inst/btamodred.m =================================================================== --- trunk/octave-forge/extra/control-devel/inst/btamodred.m 2011-12-26 21:00:43 UTC (rev 9469) +++ trunk/octave-forge/extra/control-devel/inst/btamodred.m 2011-12-27 20:41:54 UTC (rev 9470) @@ -23,14 +23,14 @@ ## ## Model order reduction by frequency weighted Balanced Truncation Approximation (BTA) method. ## The aim of model reduction is to find an LTI system @var{Gr} of order -## @var{nr} (nr << n) such that the input-output behaviour of @var{Gr} +## @var{nr} (nr < n) such that the input-output behaviour of @var{Gr} ## approximates the one from original system @var{G}. ## ## BTA is an absolute error method which tries to minimize ## @iftex ## @tex ## $$ || G - G_r ||_{\\infty} = min $$ -## $$ || W_o \\ (G - G_r) \\ W_i ||_{\\infty} = min $$ +## $$ || V \\ (G - G_r) \\ W ||_{\\infty} = min $$ ## @end tex ## @end iftex ## @ifnottex @@ -38,31 +38,13 @@ ## ||G-Gr|| = min ## inf ## -## ||Wo (G-Gr) Wi|| = min -## inf +## ||V (G-Gr) W|| = min +## inf ## @end example ## @end ifnottex -## where @var{Wo} and @var{Wi} denote output and input weightings. +## where @var{V} and @var{W} denote output and input weightings. ## -## UNSTABLE (from bstmodred) ## -## MIMO (from bstmodred) -## -## Approximation Properties: -## @itemize @bullet -## @item -## Guaranteed stability of reduced models -## @item -## Lower guaranteed error bound -## @item -## Guaranteed a priori error bound -## @iftex -## @tex -## $$ \\sigma_{r+1} \\leq || (G-G_r) ||_{\\infty} \\leq 2 \\sum_{j=r+1}^{n} \\sigma_j $$ -## @end tex -## @end iftex -## @end itemize -## ## @strong{Inputs} ## @table @var ## @item G @@ -110,15 +92,15 @@ ## Hankel singular values @var{info.hsv} > @var{tol1} are retained. ## ## @item 'left', 'output' -## LTI model of the left/output frequency weighting. +## LTI model of the left/output frequency weighting @var{V}. ## Default value is an identity matrix. ## ## @item 'right', 'input' -## LTI model of the right/input frequency weighting. +## LTI model of the right/input frequency weighting @var{W}. ## Default value is an identity matrix. ## ## @item 'method' -## Order reduction approach to be used as follows: +## Approximation method for the L-infinity norm to be used as follows: ## @table @var ## @item 'sr', 'b' ## Use the square-root Balance & Truncate method. @@ -202,6 +184,26 @@ ## false if @code{G.scaled == true}. ## @end table ## +## +## UNSTABLE (from bstmodred) +## +## MIMO (from bstmodred) +## +## Approximation Properties: +## @itemize @bullet +## @item +## Guaranteed stability of reduced models +## @item +## Lower guaranteed error bound +## @item +## Guaranteed a priori error bound +## @iftex +## @tex +## $$ \\sigma_{r+1} \\leq || (G-G_r) ||_{\\infty} \\leq 2 \\sum_{j=r+1}^{n} \\sigma_j $$ +## @end tex +## @end iftex +## @end itemize +## ## @strong{Algorithm}@* ## Uses SLICOT AB09ID by courtesy of ## @uref{http://www.slicot.org, NICONET e.V.} Modified: trunk/octave-forge/extra/control-devel/inst/cfconred.m =================================================================== --- trunk/octave-forge/extra/control-devel/inst/cfconred.m 2011-12-26 21:00:43 UTC (rev 9469) +++ trunk/octave-forge/extra/control-devel/inst/cfconred.m 2011-12-27 20:41:54 UTC (rev 9470) @@ -22,6 +22,8 @@ ## @deftypefnx{Function File} {[@var{Kr}, @var{info}] =} cfconred (@var{G}, @var{F}, @var{L}, @var{ncr}, @var{opt}, @dots{}) ## ## Reduction of state-feedback-observer based controller by coprime factorization (CF). +## Given a plant @var{G}, state feedback gain @var{F} and full observer gain @var{L}, +## determine a reduced order controller @var{Kr}. ## ## @strong{Inputs} ## @table @var Modified: trunk/octave-forge/extra/control-devel/inst/fwcfconred.m =================================================================== --- trunk/octave-forge/extra/control-devel/inst/fwcfconred.m 2011-12-26 21:00:43 UTC (rev 9469) +++ trunk/octave-forge/extra/control-devel/inst/fwcfconred.m 2011-12-27 20:41:54 UTC (rev 9470) @@ -22,6 +22,8 @@ ## @deftypefnx{Function File} {[@var{Kr}, @var{info}] =} fwcfconred (@var{G}, @var{F}, @var{L}, @var{ncr}, @var{opt}, @dots{}) ## ## Reduction of state-feedback-observer based controller by frequency-weighted coprime factorization (FW CF). +## Given a plant @var{G}, state feedback gain @var{F} and full observer gain @var{L}, +## determine a reduced order controller @var{Kr} by using stability enforcing frequency weights. ## ## @strong{Inputs} ## @table @var Modified: trunk/octave-forge/extra/control-devel/inst/hnamodred.m =================================================================== --- trunk/octave-forge/extra/control-devel/inst/hnamodred.m 2011-12-26 21:00:43 UTC (rev 9469) +++ trunk/octave-forge/extra/control-devel/inst/hnamodred.m 2011-12-27 20:41:54 UTC (rev 9470) @@ -23,14 +23,14 @@ ## ## Model order reduction by frequency weighted optimal Hankel-norm (HNA) method. ## The aim of model reduction is to find an LTI system @var{Gr} of order -## @var{nr} (nr << n) such that the input-output behaviour of @var{Gr} +## @var{nr} (nr < n) such that the input-output behaviour of @var{Gr} ## approximates the one from original system @var{G}. ## ## HNA is an absolute error method which tries to minimize ## @iftex ## @tex ## $$ || G - G_r ||_H = min $$ -## $$ || W_o \\ (G - G_r) \\ W_i ||_H = min $$ +## $$ || V \\ (G - G_r) \\ W ||_H = min $$ ## @end tex ## @end iftex ## @ifnottex @@ -38,32 +38,13 @@ ## ||G-Gr|| = min ## H ## -## ||Wo (G-Gr) Wi|| = min -## H +## ||V (G-Gr) W|| = min +## H ## @end example ## @end ifnottex -## where @var{Wo} and @var{Wi} denote output and input weightings. +## where @var{V} and @var{W} denote output and input weightings. ## -## UNSTABLE (from bstmodred) ## -## MIMO (from bstmodred) -## -## Approximation Properties: -## @itemize @bullet -## @item -## Guaranteed stability of reduced models -## @item -## Lower guaranteed error bound -## @item -## Guaranteed a priori error bound -## @iftex -## @tex -## $$ \\sigma_{r+1} \\leq || (G-G_r) ||_{\\infty} \\leq 2 \\sum_{j=r+1}^{n} \\sigma_j $$ -## @end tex -## @end iftex -## @end itemize -## -## ## @strong{Inputs} ## @table @var ## @item G @@ -266,6 +247,26 @@ ## false if @code{G.scaled == true}. ## @end table ## +## +## UNSTABLE (from bstmodred) +## +## MIMO (from bstmodred) +## +## Approximation Properties: +## @itemize @bullet +## @item +## Guaranteed stability of reduced models +## @item +## Lower guaranteed error bound +## @item +## Guaranteed a priori error bound +## @iftex +## @tex +## $$ \\sigma_{r+1} \\leq || (G-G_r) ||_{\\infty} \\leq 2 \\sum_{j=r+1}^{n} \\sigma_j $$ +## @end tex +## @end iftex +## @end itemize +## ## @strong{Algorithm}@* ## Uses SLICOT AB09JD by courtesy of ## @uref{http://www.slicot.org, NICONET e.V.} Modified: trunk/octave-forge/extra/control-devel/inst/spamodred.m =================================================================== --- trunk/octave-forge/extra/control-devel/inst/spamodred.m 2011-12-26 21:00:43 UTC (rev 9469) +++ trunk/octave-forge/extra/control-devel/inst/spamodred.m 2011-12-27 20:41:54 UTC (rev 9470) @@ -22,7 +22,29 @@ ## @deftypefnx{Function File} {[@var{Gr}, @var{info}] =} spamodred (@var{G}, @var{nr}, @var{opt}, @dots{}) ## ## Model order reduction by frequency weighted Singular Perturbation Approximation (SPA). +## The aim of model reduction is to find an LTI system @var{Gr} of order +## @var{nr} (nr < n) such that the input-output behaviour of @var{Gr} +## approximates the one from original system @var{G}. ## +## SPA is an absolute error method which tries to minimize +## @iftex +## @tex +## $$ || G - G_r ||_{\\infty} = min $$ +## $$ || V \\ (G - G_r) \\ W ||_{\\infty} = min $$ +## @end tex +## @end iftex +## @ifnottex +## @example +## ||G-Gr|| = min +## inf +## +## ||V (G-Gr) W|| = min +## inf +## @end example +## @end ifnottex +## where @var{V} and @var{W} denote output and input weightings. +## +## ## @strong{Inputs} ## @table @var ## @item G @@ -70,15 +92,15 @@ ## Hankel singular values @var{info.hsv} > @var{tol1} are retained. ## ## @item 'left', 'output' -## LTI model of the left/output frequency weighting. +## LTI model of the left/output frequency weighting @var{V}. ## Default value is an identity matrix. ## ## @item 'right', 'input' -## LTI model of the right/input frequency weighting. +## LTI model of the right/input frequency weighting @var{W}. ## Default value is an identity matrix. ## ## @item 'method' -## Order reduction approach to be used as follows: +## Approximation method for the L-infinity norm to be used as follows: ## @table @var ## @item 'sr', 's' ## Use the square-root Singular Perturbation Approximation method. 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