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.TH H_inf 1 "April 1993" "Scilab Group" "Scilab Function"
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h_inf - H-infinity (central) controller
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[Sk,ro]=h_inf(P,r,romin,romax,nmax)
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[Sk,rk,ro]=h_inf(P,r,romin,romax,nmax)
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: \fVsyslin\fR list : continuous-time linear system (``augmented'' plant given in state-space form
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: size of the \fVP22\fR plant i.e. 2-vector [#outputs,#inputs]
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: a priori bounds on \fVro\fR with \fVro=1/gama^2\fR; (\fVromin=0\fR usually)
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: integer, maximum number of iterations in the gama-iteration.
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\fVh_inf\fR computes H-infinity optimal controller for the
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continuous-time plant \fVP\fR.
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The partition of \fVP\fR into four sub-plants is given through
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the 2-vector \fVr\fR which is the size of the \fV22\fR part of \fVP\fR.
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\fVP\fR is given in state-space
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e.g. \fVP=syslin('c',A,B,C,D)\fR with \fVA,B,C,D\fR = constant matrices
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or \fVP=syslin('c',H)\fR with \fVH\fR a transfer matrix.
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.Vb [Sk,ro]=H_inf(P,r,romin,romax,nmax)
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returns \fVro\fR in \fV[romin,romax]\fR and the central controller
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\fVSk\fR in the same representation as \fVP\fR.
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(All calculations are made in state-space, i.e conversion to state-space
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is done by the function, if necessary).
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Invoked with three LHS parameters,
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.Vb [Sk,rk,ro]=H_inf(P,r,romin,romax,nmax)
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returns \fVro\fR and the Parameterization of all stabilizing
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a stabilizing controller \fVK\fR is obtained by
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\fVK=lft(Sk,r,PHI)\fR where \fVPHI\fR is a linear system with
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dimensions \fVr'\fR and satisfy:
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\fVH_norm(PHI) < gamma\fR.
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\fVrk (=r)\fR is the size of the \fVSk22\fR block and \fVro = 1/gama^2\fR
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after \fVnmax\fR iterations.
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Algorithm is adapted from Safonov-Limebeer. Note that \fVP\fR is assumed to be
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a continuous-time plant.