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fixed bug in calculation of percent overshoot #555

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Merged
merged 2 commits into from
Mar 8, 2021
Merged

fixed bug in calculation of percent overshoot #555

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9c87a5b
fixed bug in calculation of pct overshoot that neglects not strictly …
sawyerbfuller Mar 4, 2021
b36d053
slight adjustment of decay time in step response
sawyerbfuller Mar 4, 2021
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12 changes: 4 additions & 8 deletions control/tests/sisotool_test.py
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Original file line number Diff line number Diff line change
Expand Up @@ -67,12 +67,9 @@ def test_sisotool(self, sys):
initial_point_2, 4)

# Check the step response before moving the point
# new array needed because change in compute step response default time
step_response_original = np.array(
[0. , 0.0069, 0.0448, 0.124 , 0.2427, 0.3933, 0.5653, 0.7473,
0.928 , 1.0969])
#old: np.array([0., 0.0217, 0.1281, 0.3237, 0.5797, 0.8566, 1.116,
# 1.3261, 1.4659, 1.526])
[0. , 0.021 , 0.124 , 0.3146, 0.5653, 0.8385, 1.0969, 1.3095,
1.4549, 1.5231])
assert_array_almost_equal(
ax_step.lines[0].get_data()[1][:10], step_response_original, 4)

Expand Down Expand Up @@ -115,10 +112,9 @@ def test_sisotool(self, sys):
bode_mag_moved, 4)

# Check if the step response has changed
# new array needed because change in compute step response default time
step_response_moved = np.array(
[0., 0.0072, 0.0516, 0.1554, 0.3281, 0.5681, 0.8646, 1.1987,
1.5452, 1.875])
[0. , 0.023 , 0.1554, 0.4401, 0.8646, 1.3722, 1.875 , 2.2709,
2.4633, 2.3827])
assert_array_almost_equal(
ax_step.lines[0].get_data()[1][:10], step_response_moved, 4)

Expand Down
6 changes: 5 additions & 1 deletion control/tests/timeresp_test.py
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Original file line number Diff line number Diff line change
Expand Up @@ -310,6 +310,10 @@ def test_step_pole_cancellation(self, pole_cancellation,
step_info_no_cancellation = step_info(no_pole_cancellation)
step_info_cancellation = step_info(pole_cancellation)
for key in step_info_no_cancellation:
if key == 'Overshoot':
# skip this test because these systems have no overshoot
# => very sensitive to parameters
continue
np.testing.assert_allclose(step_info_no_cancellation[key],
step_info_cancellation[key], rtol=1e-4)

Expand Down Expand Up @@ -522,7 +526,7 @@ def test_step_robustness(self):

@pytest.mark.parametrize(
"tfsys, tfinal",
[(TransferFunction(1, [1, .5]), 9.21034), # pole at 0.5
[(TransferFunction(1, [1, .5]), 13.81551), # pole at 0.5
(TransferFunction(1, [1, .5]).sample(.1), 25), # discrete pole at 0.5
(TransferFunction(1, [1, .5, 0]), 25)]) # poles at 0.5 and 0
def test_auto_generated_time_vector_tfinal(self, tfsys, tfinal):
Expand Down
6 changes: 3 additions & 3 deletions control/timeresp.py
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Original file line number Diff line number Diff line change
Expand Up @@ -792,7 +792,7 @@ def step_info(sys, T=None, T_num=None, SettlingTimeThreshold=0.02,
T, yout = step_response(sys, T)

# Steady state value
InfValue = yout[-1]
InfValue = sys.dcgain()

# RiseTime
tr_lower_index = (np.where(yout >= RiseTimeLimits[0] * InfValue)[0])[0]
Expand All @@ -814,7 +814,7 @@ def step_info(sys, T=None, T_num=None, SettlingTimeThreshold=0.02,
'SettlingTime': SettlingTime,
'SettlingMin': yout[tr_upper_index:].min(),
'SettlingMax': yout.max(),
'Overshoot': 100. * (yout.max() - InfValue) / (InfValue - yout[0]),
'Overshoot': 100. * (yout.max() - InfValue) / InfValue,
'Undershoot': yout.min(), # not very confident about this
'Peak': yout[PeakIndex],
'PeakTime': T[PeakIndex],
Expand Down Expand Up @@ -1124,7 +1124,7 @@ def _ideal_tfinal_and_dt(sys, is_step=True):
default_dt = 0.1
total_cycles = 5 # number of cycles for oscillating modes
pts_per_cycle = 25 # Number of points divide a period of oscillation
log_decay_percent = np.log(100) # Factor of reduction for real pole decays
log_decay_percent = np.log(1000) # Factor of reduction for real pole decays

if sys._isstatic():
tfinal = default_tfinal
Expand Down