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May 2, 2019
Merged

fix time series inconsistency between continuous and discrete time simulations #295

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3120e01
fix time series inconsistency between continuous and discrete time
murrayrm Apr 21, 2019
f474179
code cleanup in response to review
murrayrm May 2, 2019
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103 changes: 85 additions & 18 deletions control/tests/timeresp_test.py
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Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,6 @@

import unittest
import numpy as np
# import scipy as sp
from control.timeresp import *
from control.statesp import *
from control.xferfcn import TransferFunction, _convert_to_transfer_function
Expand Down Expand Up @@ -309,7 +308,7 @@ def check(u, x0, xtrue):
def test_discrete_initial(self):
h1 = TransferFunction([1.], [1., 0.], 1.)
t, yout = impulse_response(h1, np.arange(4))
np.testing.assert_array_equal(yout[0], [0., 1., 0., 0.])
np.testing.assert_array_equal(yout, [0., 1., 0., 0.])

@unittest.skipIf(not slycot_check(), "slycot not installed")
def test_step_robustness(self):
Expand Down Expand Up @@ -345,27 +344,32 @@ def test_time_vector(self):
# No timebase in system => output should match input
#
# Initial response
tout, yout = initial_response(self.siso_dtf1, Tin2, siso_x0)
tout, yout = initial_response(self.siso_dtf1, Tin2, siso_x0,
squeeze=False)
self.assertEqual(np.shape(tout), np.shape(yout[0,:]))
np.testing.assert_array_equal(tout, Tin2)

# Impulse response
tout, yout = impulse_response(self.siso_dtf1, Tin2)
tout, yout = impulse_response(self.siso_dtf1, Tin2,
squeeze=False)
self.assertEqual(np.shape(tout), np.shape(yout[0,:]))
np.testing.assert_array_equal(tout, Tin2)

# Step response
tout, yout = step_response(self.siso_dtf1, Tin2)
tout, yout = step_response(self.siso_dtf1, Tin2,
squeeze=False)
self.assertEqual(np.shape(tout), np.shape(yout[0,:]))
np.testing.assert_array_equal(tout, Tin2)

# Forced response with specified time vector
tout, yout, xout = forced_response(self.siso_dtf1, Tin2, np.sin(Tin2))
tout, yout, xout = forced_response(self.siso_dtf1, Tin2, np.sin(Tin2),
squeeze=False)
self.assertEqual(np.shape(tout), np.shape(yout[0,:]))
np.testing.assert_array_equal(tout, Tin2)

# Forced response with no time vector, no sample time (should use 1)
tout, yout, xout = forced_response(self.siso_dtf1, None, np.sin(Tin1))
tout, yout, xout = forced_response(self.siso_dtf1, None, np.sin(Tin1),
squeeze=False)
self.assertEqual(np.shape(tout), np.shape(yout[0,:]))
np.testing.assert_array_equal(tout, Tin1)

Expand All @@ -380,49 +384,58 @@ def test_time_vector(self):
# Matching timebase in system => output should match input
#
# Initial response
tout, yout = initial_response(self.siso_dtf2, Tin2, siso_x0)
tout, yout = initial_response(self.siso_dtf2, Tin2, siso_x0,
squeeze=False)
self.assertEqual(np.shape(tout), np.shape(yout[0,:]))
np.testing.assert_array_equal(tout, Tin2)

# Impulse response
tout, yout = impulse_response(self.siso_dtf2, Tin2)
tout, yout = impulse_response(self.siso_dtf2, Tin2,
squeeze=False)
self.assertEqual(np.shape(tout), np.shape(yout[0,:]))
np.testing.assert_array_equal(tout, Tin2)

# Step response
tout, yout = step_response(self.siso_dtf2, Tin2)
tout, yout = step_response(self.siso_dtf2, Tin2,
squeeze=False)
self.assertEqual(np.shape(tout), np.shape(yout[0,:]))
np.testing.assert_array_equal(tout, Tin2)

# Forced response
tout, yout, xout = forced_response(self.siso_dtf2, Tin2, np.sin(Tin2))
tout, yout, xout = forced_response(self.siso_dtf2, Tin2, np.sin(Tin2),
squeeze=False)
self.assertEqual(np.shape(tout), np.shape(yout[0,:]))
np.testing.assert_array_equal(tout, Tin2)

# Forced response with no time vector, use sample time
tout, yout, xout = forced_response(self.siso_dtf2, None, np.sin(Tin2))
tout, yout, xout = forced_response(self.siso_dtf2, None, np.sin(Tin2),
squeeze=False)
self.assertEqual(np.shape(tout), np.shape(yout[0,:]))
np.testing.assert_array_equal(tout, Tin2)

# Compatible timebase in system => output should match input
#
# Initial response
tout, yout = initial_response(self.siso_dtf2, Tin1, siso_x0)
tout, yout = initial_response(self.siso_dtf2, Tin1, siso_x0,
squeeze=False)
self.assertEqual(np.shape(tout), np.shape(yout[0,:]))
np.testing.assert_array_equal(tout, Tin1)

# Impulse response
tout, yout = impulse_response(self.siso_dtf2, Tin1)
tout, yout = impulse_response(self.siso_dtf2, Tin1,
squeeze=False)
self.assertEqual(np.shape(tout), np.shape(yout[0,:]))
np.testing.assert_array_equal(tout, Tin1)

# Step response
tout, yout = step_response(self.siso_dtf2, Tin1)
tout, yout = step_response(self.siso_dtf2, Tin1,
squeeze=False)
self.assertEqual(np.shape(tout), np.shape(yout[0,:]))
np.testing.assert_array_equal(tout, Tin1)

# Forced response
tout, yout, xout = forced_response(self.siso_dtf2, Tin1, np.sin(Tin1))
tout, yout, xout = forced_response(self.siso_dtf2, Tin1, np.sin(Tin1),
squeeze=False)
self.assertEqual(np.shape(tout), np.shape(yout[0,:]))
np.testing.assert_array_equal(tout, Tin1)

Expand All @@ -431,7 +444,8 @@ def test_time_vector(self):
#
# Initial response
tout, yout, xout = forced_response(self.siso_dtf2, Tin1,
np.sin(Tin1), interpolate=True)
np.sin(Tin1), interpolate=True,
squeeze=False)
self.assertEqual(np.shape(tout), np.shape(yout[0,:]))
self.assertTrue(np.allclose(tout[1:] - tout[:-1], self.siso_dtf2.dt))

Expand All @@ -442,9 +456,62 @@ def test_time_vector(self):
#
# Initial response
with self.assertRaises(Exception) as context:
tout, yout = initial_response(self.siso_dtf2, Tin3, siso_x0)
tout, yout = initial_response(self.siso_dtf2, Tin3, siso_x0,
squeeze=False)
self.assertTrue(isinstance(context.exception, ValueError))

def test_time_series_data_convention(self):
"""Make sure time series data matches documentation conventions"""
# SISO continuous time
t, y = step_response(self.siso_ss1)
self.assertTrue(isinstance(t, np.ndarray)
and not isinstance(t, np.matrix))
self.assertTrue(len(t.shape) == 1)
self.assertTrue(len(y.shape) == 1) # SISO returns "scalar" output
self.assertTrue(len(t) == len(y)) # Allows direct plotting of output

# SISO discrete time
t, y = step_response(self.siso_dss1)
self.assertTrue(isinstance(t, np.ndarray)
and not isinstance(t, np.matrix))
self.assertTrue(len(t.shape) == 1)
self.assertTrue(len(y.shape) == 1) # SISO returns "scalar" output
self.assertTrue(len(t) == len(y)) # Allows direct plotting of output

# MIMO continuous time
tin = np.linspace(0, 10, 100)
uin = [np.sin(tin), np.cos(tin)]
t, y, x = forced_response(self.mimo_ss1, tin, uin)
self.assertTrue(isinstance(t, np.ndarray)
and not isinstance(t, np.matrix))
self.assertTrue(len(t.shape) == 1)
self.assertTrue(len(y[0].shape) == 1)
self.assertTrue(len(y[1].shape) == 1)
self.assertTrue(len(t) == len(y[0]))
self.assertTrue(len(t) == len(y[1]))

# MIMO discrete time
tin = np.linspace(0, 10, 100)
uin = [np.sin(tin), np.cos(tin)]
t, y, x = forced_response(self.mimo_dss1, tin, uin)
self.assertTrue(isinstance(t, np.ndarray)
and not isinstance(t, np.matrix))
self.assertTrue(len(t.shape) == 1)
self.assertTrue(len(y[0].shape) == 1)
self.assertTrue(len(y[1].shape) == 1)
self.assertTrue(len(t) == len(y[0]))
self.assertTrue(len(t) == len(y[1]))

# Allow input time as 2D array (output should be 1D)
tin = np.array(np.linspace(0, 10, 100), ndmin=2)
t, y = step_response(self.siso_ss1, tin)
self.assertTrue(isinstance(t, np.ndarray)
and not isinstance(t, np.matrix))
self.assertTrue(len(t.shape) == 1)
self.assertTrue(len(y.shape) == 1) # SISO returns "scalar" output
self.assertTrue(len(t) == len(y)) # Allows direct plotting of output


def suite():
return unittest.TestLoader().loadTestsFromTestCase(TestTimeresp)

Expand Down
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