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Merged
murrayrm merged 6 commits into from
Jan 6, 2018
Merged

H-infinity mixed-synthesis #151

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77d0ccd
BUG: allow empty (no input or output) StateSpace objects
roryyorke Dec 30, 2016
78f0c7f
Augmented plant and mixed-sythensis H-infinity design
roryyorke Jun 23, 2017
7b883ef
SISO and MIMO mixed-sensitivity synthesis examples
roryyorke Jul 1, 2017
e24c7de
Fixups following review
roryyorke Jan 5, 2018
7d70fb4
DOC: add mixsyn and augw to documentation
murrayrm Jan 6, 2018
36e0b0f
DOC: updated mixsyn docstring to use standard 'see also' format
murrayrm Jan 6, 2018
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BUG: allow empty (no input or output) StateSpace objects
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@roryyorke
roryyorke committed Jan 2, 2018
commit 77d0ccdeb18caedf7c3c24e67cd2a89316868df0
27 changes: 19 additions & 8 deletions control/statesp.py
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Expand Up @@ -54,7 +54,7 @@
import math
import numpy as np
from numpy import all, angle, any, array, asarray, concatenate, cos, delete, \
dot, empty, exp, eye, matrix, ones, poly, poly1d, roots, shape, sin, \
dot, empty, exp, eye, matrix, ones, pi, poly, poly1d, roots, shape, sin, \

@murrayrm murrayrm Jan 4, 2018

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We should avoid using numpy.pi since this can generate errors when numpy is incorporated as a mock function. See PR 171, commit b881b7. Replace with math.pi.

@roryyorke roryyorke Jan 5, 2018

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unqualified pi no longer used following your aa6e0df anyway. Will remove.

zeros, squeeze
from numpy.random import rand, randn
from numpy.linalg import solve, eigvals, matrix_rank
Expand All @@ -69,6 +69,19 @@

__all__ = ['StateSpace', 'ss', 'rss', 'drss', 'tf2ss', 'ssdata']


def _matrix(a):
"""_matrix(a) -> numpy.matrix
a - passed to numpy.matrix
Wrapper around numpy.matrix; unlike that function, _matrix([]) will be 0x0

@murrayrm murrayrm Jan 4, 2018

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Not clear to my why this is useful? Can you say a bit here (or in a comment in the code)?

@roryyorke roryyorke Jan 5, 2018

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I'll expand the commentary; it's just a helper to make it easier to get 0x0 matrices, which are needed for empty state space systems.

"""
from numpy import matrix
am = matrix(a)
if (1,0) == am.shape:
am.shape = (0,0)
return am


class StateSpace(LTI):
"""StateSpace(A, B, C, D[, dt])

Expand Down Expand Up @@ -130,7 +143,7 @@ def __init__(self, *args):
else:
raise ValueError("Needs 1 or 4 arguments; received %i." % len(args))

A, B, C, D = map(matrix, [A, B, C, D])
A, B, C, D = [_matrix(M) for M in (A, B, C, D)]

# TODO: use super here?
LTI.__init__(self, inputs=D.shape[1], outputs=D.shape[0], dt=dt)
Expand Down Expand Up @@ -336,7 +349,7 @@ def __rmul__(self, other):

# try to treat this as a matrix
try:
X = matrix(other)
X = _matrix(other)
C = X * self.C
D = X * self.D
return StateSpace(self.A, self.B, C, D, self.dt)
Expand Down Expand Up @@ -727,11 +740,9 @@ def _convertToStateSpace(sys, **kw):

# If this is a matrix, try to create a constant feedthrough
try:
D = matrix(sys)
outputs, inputs = D.shape

return StateSpace(0., zeros((1, inputs)), zeros((outputs, 1)), D)
except Exception(e):
D = _matrix(sys)
return StateSpace([], [], [], D)
except Exception as e:
print("Failure to assume argument is matrix-like in" \
" _convertToStateSpace, result %s" % e)

Expand Down
22 changes: 22 additions & 0 deletions control/tests/statesp_test.py
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Expand Up @@ -350,6 +350,28 @@ def test_minrealStaticGain(self):
np.testing.assert_array_equal(g1.D, g2.D)


def test_Empty(self):
"""Regression: can we create an empty StateSpace object?"""
g1=StateSpace([],[],[],[])
self.assertEqual(0,g1.states)
self.assertEqual(0,g1.inputs)
self.assertEqual(0,g1.outputs)


def test_MatrixToStateSpace(self):
"""_convertToStateSpace(matrix) gives ss([],[],[],D)"""
D = np.matrix([[1,2,3],[4,5,6]])
g = _convertToStateSpace(D)
def empty(shape):
m = np.matrix([])
m.shape = shape
return m
np.testing.assert_array_equal(empty((0,0)), g.A)
np.testing.assert_array_equal(empty((0,D.shape[1])), g.B)
np.testing.assert_array_equal(empty((D.shape[0],0)), g.C)
np.testing.assert_array_equal(D,g.D)


class TestRss(unittest.TestCase):
"""These are tests for the proper functionality of statesp.rss."""

Expand Down