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Step info improve jpp #567

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Merged
merged 4 commits into from
Mar 17, 2021

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juanodecc
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This modification improve step_info results:

Solve the issue Any plan for step_info to support negative step responses? #337
solve the issue step_info problem with non stationary systems response #564
solve the issue step_info undershoot must be "Undershoot: Percentage of undershoot" #565

I try to fullfill pep 8
Add some aditional tests to check the results

1) System Type 1 - Step response not stationary:  G(s)=1/s(s+1)
2) SISO system with under shoot response and positive final value G(s)=(-s+1)/(s²+s+1)
3) Same system that 2) with k=-1
4) example from matlab online help https://www.mathworks.com/help/control/ref/stepinfo.html G(s)=(s²+5s+5)/(s^4+1.65s^3+6.5s+2)

with stepinfo output:

        RiseTime: 3.8456
    SettlingTime: 27.9762
     SettlingMin: 2.0689
     SettlingMax: 2.6873
       Overshoot: 7.4915
      Undershoot: 0
            Peak: 2.6873
        PeakTime: 8.0530

5) example from matlab online help https://www.mathworks.com/help/control/ref/stepinfo.html
A = [0.68 -0.34; 0.34 0.68];
B = [0.18 -0.05; 0.04 0.11];
C = [0 -1.53; -1.12 -1.10];
D = [0 0; 0.06 -0.37];
sys = StateSpace(A,B,C,D,0.2);
examine the response characteristics for the response from the first input to the second output of sys.

with stepinfo output:

        RiseTime: 0.4000
    SettlingTime: 2.8000
     SettlingMin: -0.6724
     SettlingMax: -0.5188
       Overshoot: 24.6476
      Undershoot: 11.1224
            Peak: 0.6724
        PeakTime: 1
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coveralls commented Mar 12, 2021

Coverage Status

Coverage decreased (-0.03%) to 88.832% when pulling 81ae64f on juanodecc:step_info_improve_jpp into 92de12d on python-control:master.

Comment on lines +798 to +805
rise_time: float = np.NaN
settling_time: float = np.NaN
settling_min: float = np.NaN
settling_max: float = np.NaN
peak_value: float = np.Inf
peak_time: float = np.Inf
undershoot: float = np.NaN
overshoot: float = np.NaN
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The first use of typing in python-control?

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yes, is wrong?

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Not at all! Good thing we already ditched Python 2.

Comment on lines 816 to 838
if InfValue < 0.0:
# RiseTime
tr_lower_index = (np.where(yout <= RiseTimeLimits[0] * InfValue)[0])[0]
tr_upper_index = (np.where(yout <= RiseTimeLimits[1] * InfValue)[0])[0]
# SettlingTime
for i in reversed(range(T.size - 1)):
if (-yout[i] <= np.abs(inf_margin)) | (-yout[i] >= np.abs(sup_margin)):
settling_time = T[i + 1]
break
# Overshoot and Undershoot
overshoot = np.abs(100. * ((-yout).max() - np.abs(InfValue)) / np.abs(InfValue))
undershoot = np.abs(100. * (-yout).min() / np.abs(InfValue))
else:
tr_lower_index = (np.where(yout >= RiseTimeLimits[0] * InfValue)[0])[0]
tr_upper_index = (np.where(yout >= RiseTimeLimits[1] * InfValue)[0])[0]
# SettlingTime
for i in reversed(range(T.size - 1)):
if (yout[i] <= inf_margin) | (yout[i] >= sup_margin):
settling_time = T[i + 1]
break
# Overshoot and Undershoot
overshoot = np.abs(100. * (yout.max() - InfValue) / InfValue)
undershoot = np.abs(100. * yout.min() / InfValue)
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@bnavigator bnavigator Mar 12, 2021

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Hmm, this has a lot of duplicate code. Have you considered using a sign variable and the abs() function instead of two completely separate blocks? I think It won't turn out much more convoluted than the current InfValue < 0 part.

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ok

juanodecc and others added 2 commits March 16, 2021 11:16
systems converting to SISO systems from input=0 to output =0
solve problems with non stationary systems doing
SteadyStateValue= nan when  y_final is inf
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Other than the MIMO handling (#574), this looks good to me. I'll merge this. Future PRs can improve it further.

@bnavigator bnavigator merged commit 258c9c2 into python-control:master Mar 17, 2021
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