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Bug fix and improvements to Nyquist plots #722

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Merged
merged 11 commits into from
Apr 25, 2022
Merged

Bug fix and improvements to Nyquist plots #722

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18e997c
add warning for nyquist_plot() when indent_radius is too large
murrayrm Apr 10, 2022
1e12a51
add warning for nyquist_plot() when Nyquist criterion isn't met
murrayrm Apr 10, 2022
6da8706
add code to limit magnitude of response and enhance contour near poles
murrayrm Apr 10, 2022
3d3a559
smooth curve offsets to avoid discontinuities
murrayrm Apr 11, 2022
aef3b06
tweak max_curve_magnitude + add start point
murrayrm Apr 13, 2022
c25c0cb
add warning if encirclements is not near an integer
murrayrm Apr 14, 2022
67c1f3f
add legacy settings for nyquist
murrayrm Apr 15, 2022
9a5759f
increase coverage; PEP8 cleanup
murrayrm Apr 15, 2022
5dd6a70
turn off encirclement warnings for describing function plot
murrayrm Apr 15, 2022
5d9c7f0
rebase cleanup
murrayrm Apr 16, 2022
7407265
Fixed docstrings per roryyorke plus discrete-time corrections
murrayrm Apr 16, 2022
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9 changes: 9 additions & 0 deletions control/config.py
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Original file line number Diff line number Diff line change
Expand Up @@ -267,6 +267,15 @@ def use_legacy_defaults(version):
#
reset_defaults() # start from a clean slate

# Version 0.9.2:
if major == 0 and minor < 9 or (minor == 9 and patch < 2):
from math import inf

# Reset Nyquist defaults
set_defaults('nyquist', indent_radius=0.1, max_curve_magnitude=inf,
max_curve_offset=0, primary_style=['-', '-'],
mirror_style=['--', '--'], start_marker_size=0)

# Version 0.9.0:
if major == 0 and minor < 9:
# switched to 'array' as default for state space objects
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15 changes: 13 additions & 2 deletions control/descfcn.py
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Expand Up @@ -199,7 +199,8 @@ def describing_function(


def describing_function_plot(
H, F, A, omega=None, refine=True, label="%5.2g @ %-5.2g", **kwargs):
H, F, A, omega=None, refine=True, label="%5.2g @ %-5.2g",
warn=None, **kwargs):
"""Plot a Nyquist plot with a describing function for a nonlinear system.

This function generates a Nyquist plot for a closed loop system consisting
Expand All @@ -220,6 +221,10 @@ def describing_function_plot(
label : str, optional
Formatting string used to label intersection points on the Nyquist
plot. Defaults to "%5.2g @ %-5.2g". Set to `None` to omit labels.
warn : bool, optional
Set to True to turn on warnings generated by `nyquist_plot` or False
to turn off warnings. If not set (or set to None), warnings are
turned off if omega is specified, otherwise they are turned on.

Returns
-------
Expand All @@ -240,9 +245,15 @@ def describing_function_plot(
[(3.344008947853124, 1.414213099755523)]

"""
# Decide whether to turn on warnings or not
if warn is None:
# Turn warnings on unless omega was specified
warn = omega is None

# Start by drawing a Nyquist curve
count, contour = nyquist_plot(
H, omega, plot=True, return_contour=True, **kwargs)
H, omega, plot=True, return_contour=True,
warn_encirclements=warn, warn_nyquist=warn, **kwargs)
H_omega, H_vals = contour.imag, H(contour)

# Compute the describing function
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