[Octave-cvsupdate] SF.net SVN: octave:[10895] trunk/octave-forge/main/control/devel/ sensitivity.m

[<par...@us...>]

Revision: 10895
          http://octave.svn.sourceforge.net/octave/?rev=10895&view=rev
Author:   paramaniac
Date:     2012-08-23 07:30:41 +0000 (Thu, 23 Aug 2012)
Log Message:
-----------
control: add sensitivity function

Added Paths:
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    trunk/octave-forge/main/control/devel/sensitivity.m

Added: trunk/octave-forge/main/control/devel/sensitivity.m
===================================================================
--- trunk/octave-forge/main/control/devel/sensitivity.m	                        (rev 0)
+++ trunk/octave-forge/main/control/devel/sensitivity.m	2012-08-23 07:30:41 UTC (rev 10895)
@@ -0,0 +1,84 @@
+## Copyright (C) 2012   Lukas F. Reichlin
+##
+## This file is part of LTI Syncope.
+##
+## LTI Syncope is free software: you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation, either version 3 of the License, or
+## (at your option) any later version.
+##
+## LTI Syncope is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with LTI Syncope.  If not, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn{Function File} {@var{Ms} =} sensitivity (@var{L})
+## @deftypefnx{Function File} {@var{Ms} =} sensitivity (@var{P}, @var{C})
+## @deftypefnx{Function File} {@var{Ms} =} sensitivity (@var{P}, @var{C1}, @var{C2}, @dots{})
+## Return sensitivity margin @var{Ms}.
+##
+## @strong{Inputs}
+## @table @var
+## @item L
+## Open loop transfer function.
+## @var{L} can be any type of LTI system, but it must be square.
+## @item P
+## Plant model.  Any type of LTI system.
+## @item C
+## Controller model.  Any type of LTI system.
+## @item C1, C2, @dots{}
+## If several controllers are specified, command @command{sensitivity}
+## computes the sensitivity @var{Ms} for each of them in combination
+## with plant @var{P}.
+## @end table
+##
+## @strong{Outputs}
+## @table @var
+## @item Ms
+## Sensitivity margin @var{Ms} as defined in [1].  Scalar value.
+## If several controllers are specified, @var{Ms} becomes
+## a vector with as many entries as controllers.
+## @end table
+##
+## @strong{Algorithm}@*
+## Uses SLICOT AB13DD by courtesy of
+## @uref{http://www.slicot.org, NICONET e.V.}
+##
+## @strong{References}@*
+## [1] Astr@"om, K. and H@"agglund, T. (1995)
+## PID Controllers:
+## Theory, Design and Tuning,
+## Second Edition.
+## Instrument Society of America.
+##
+## @end deftypefn
+
+## Author: Lukas Reichlin <luk...@gm...>
+## Created: August 2012
+## Version: 0.1
+
+function Ms = sensitivity (G, varargin)
+
+  ## TODO: show nyquist diagram of L with circle
+  ##       center (-1, 0) and radius equal to the
+  ##       shortest distance 1/Ms, frequency w is
+  ##       [Ms, w] = norm (S, inf)
+
+  if (nargin == 0)
+    print_usage ();
+  elseif (nargin == 1)              # L := G
+    I = eye (size (G));
+    S = feedback (I, G);            # S = inv (I + G),  S = feedback (I, G*-I, "+")
+    Ms = norm (S, inf);
+  else                              # P := G,  C := varargin
+    L = cellfun (@(C) G*C, varargin, "uniformoutput", false);
+    I = cellfun (@(L) eye (size (L)), L, "uniformoutput", false);
+    S = cellfun (@feedback, I, L, "uniformoutput", false);
+    Ms = cellfun (@(S) norm (S, inf), S);
+  endif
+
+endfunction

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