# robust.py - tools for robust control

#

# Author: Steve Brunton, Kevin Chen, Lauren Padilla

# Date: 24 Dec 2010

#

# This file contains routines for obtaining reduced order models

#

# Copyright (c) 2010 by California Institute of Technology

# All rights reserved.

#

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# modification, are permitted provided that the following conditions

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#

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#

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#

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# $Id: robust.py 216 2012-11-03 03:23:13Z murrayrm $

# External packages and modules

import numpy as np

import control.ctrlutil as ctrlutil

from control.exception import *

from control.statesp import StateSpace

from control.statefbk import *

def h2syn(P,nmeas,ncon):

"""H_2 control synthesis for plant P.

Parameters

----------

P: partitioned lti plant (State-space sys)

nmeas: number of measurements (input to controller)

ncon: number of control inputs (output from controller)

Returns

-------

K: controller to stabilize P (State-space sys)

Raises

------

ImportError

if slycot routine sb10hd is not loaded

See Also

--------

StateSpace

Examples

--------

>>> K = h2syn(P,nmeas,ncon)

"""

#Check for ss system object, need a utility for this?

#TODO: Check for continous or discrete, only continuous supported right now

# if isCont():

# dico = 'C'

# elif isDisc():

# dico = 'D'

# else:

dico = 'C'

try:

from slycot import sb10hd

except ImportError:

raise ControlSlycot("can't find slycot subroutine sb10hd")

n = np.size(P.A,0)

m = np.size(P.B,1)

np = np.size(P.C,0)

out = sb10hd(n,m,np,ncon,nmeas,P.A,P.B,P.C,P.D)

Ak = out[0]

Bk = out[1]

Ck = out[2]

Dk = out[3]

K = StateSpace(Ak, Bk, Ck, Dk)

return K

def hinfsyn(P,nmeas,ncon):

"""H_{inf} control synthesis for plant P.

Parameters

----------

P: partitioned lti plant

nmeas: number of measurements (input to controller)

ncon: number of control inputs (output from controller)

Returns

-------

K: controller to stabilize P (State-space sys)

CL: closed loop system (State-space sys)

gam: infinity norm of closed loop system

info: info returned from siycot routine

Raises

------

ImportError

if slycot routine sb10ad is not loaded

See Also

--------

StateSpace

Examples

--------

>>> K, CL, gam, info = hinfsyn(P,nmeas,ncon)

"""

#Check for ss system object, need a utility for this?

#TODO: Check for continous or discrete, only continuous supported right now

# if isCont():

# dico = 'C'

# elif isDisc():

# dico = 'D'

# else:

dico = 'C'

try:

from slycot import sb10ad

except ImportError:

raise ControlSlycot("can't find slycot subroutine sb10ad")

job = 3

n = np.size(P.A,0)

m = np.size(P.B,1)

np = np.size(P.C,0)

gamma = 1.e100

out = sb10ad(job,n,m,np,ncon,nmeas,gamma,P.A,P.B,P.C,P.D)

gam = out[0]

Ak = out[1]

Bk = out[2]

Ck = out[3]

Dk = out[4]

Ac = out[5]

Bc = out[6]

Cc = out[7]

Dc = out[8]

rcond = out[9]

info = out[10]

K = StateSpace(Ak, Bk, Ck, Dk)

CL = StateSpace(Ac, Bc, Cc, Dc)

return K, CL, gam, info