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Don't fail in step_info() if the rise-time level is never reached #1259

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syahra712 wants to merge 1 commit into from
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Don't fail in step_info() if the rise-time level is never reached #1259

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19 changes: 19 additions & 0 deletions control/tests/timeresp_test.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1483,3 +1483,22 @@ def test_timeresp_aliases():

with pytest.raises(TypeError, match="unrecognized keyword"):
ct.step_info(sys, timepts, unknown=True)


def test_step_info_rise_not_reached():
# Response that never reaches 90% of the final value: the rise time
# (and settling min/max) are undefined, but step_info should not fail
timepts = np.linspace(0, 1, 101)
yout = 1 - np.exp(-timepts)
step_info = ct.step_info(yout, timepts, yfinal=1)
assert np.isnan(step_info['RiseTime'])
assert np.isnan(step_info['SettlingMin'])
assert np.isnan(step_info['SettlingMax'])
assert np.isnan(step_info['SettlingTime'])
assert step_info['SteadyStateValue'] == 1

# Large feedthrough: default time vector ends before 90% is reached
sys = ct.tf([2.99, -0.0685], [1, 2.83])
step_info = ct.step_info(sys)
assert isclose(step_info['SteadyStateValue'], sys.dcgain())
assert step_info['Peak'] == pytest.approx(2.99)
24 changes: 14 additions & 10 deletions control/timeresp.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1698,14 +1698,15 @@ def step_info(
steady_state_value: complex = np.nan

if not np.isnan(InfValue) and not np.isinf(InfValue):
# RiseTime
tr_lower_index = np.nonzero(
sgnInf * (yout - RiseTimeLimits[0] * InfValue) >= 0
)[0][0]
tr_upper_index = np.nonzero(
sgnInf * (yout - RiseTimeLimits[1] * InfValue) >= 0
)[0][0]
rise_time = T[tr_upper_index] - T[tr_lower_index]
# RiseTime (undefined if the response never gets there,
# e.g. if the time vector is too short)
tr_lower = np.nonzero(
sgnInf * (yout - RiseTimeLimits[0] * InfValue) >= 0)[0]
tr_upper = np.nonzero(
sgnInf * (yout - RiseTimeLimits[1] * InfValue) >= 0)[0]
if tr_lower.size and tr_upper.size:
tr_upper_index = tr_upper[0]
rise_time = T[tr_upper_index] - T[tr_lower[0]]

# SettlingTime
outside_threshold = np.nonzero(
Expand All @@ -1717,8 +1718,11 @@ def step_info(
if settled < len(T):
settling_time = T[settled]

settling_min = min((yout[tr_upper_index:]).min(), InfValue)
settling_max = max((yout[tr_upper_index:]).max(), InfValue)
if tr_lower.size and tr_upper.size:
settling_min = min(
(yout[tr_upper_index:]).min(), InfValue)
settling_max = max(
(yout[tr_upper_index:]).max(), InfValue)

# Overshoot
y_os = (sgnInf * yout).max()
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