Skip to content

Fix timebase bug in InterconnectedSystem (issue #754) #755

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 3 commits into from
Aug 6, 2022
Merged

Fix timebase bug in InterconnectedSystem (issue #754) #755

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
f17c919
fix timebase bug in InterconnectedSystem (issue #754)
murrayrm Aug 4, 2022
3c13f2c
add additional checks for overriding timebase
murrayrm Aug 4, 2022
cf30479
added tests for dt=True case per @sawyerbfuller suggestion
murrayrm Aug 4, 2022
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
7 changes: 5 additions & 2 deletions control/iosys.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -871,9 +871,12 @@ def __init__(self, syslist, connections=[], inplist=[], outlist=[],
if not isinstance(outlist, (list, tuple)):
outlist = [outlist]

# Process keyword arguments
# Check if dt argument was given; if not, pull from systems
dt = kwargs.pop('dt', None)

# Process keyword arguments (except dt)
defaults = {'inputs': len(inplist), 'outputs': len(outlist)}
name, inputs, outputs, states, dt = _process_namedio_keywords(
name, inputs, outputs, states, _ = _process_namedio_keywords(
kwargs, defaults, end=True)

# Initialize the system list and index
Expand Down
69 changes: 69 additions & 0 deletions control/tests/timebase_test.py
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,69 @@
import pytest
import inspect
import numpy as np
import control as ct

@pytest.mark.parametrize(
"dt1, dt2, dt3", [
(0, 0, 0),
(0, 0.1, ValueError),
(0, None, 0),
(0, True, ValueError),
(0.1, 0, ValueError),
(0.1, 0.1, 0.1),
(0.1, None, 0.1),
(0.1, True, 0.1),
(None, 0, 0),
(None, 0.1, 0.1),
(None, None, None),
(None, True, True),
(True, 0, ValueError),
(True, 0.1, 0.1),
(True, None, True),
(True, True, True),
(0.2, None, 0.2),
(0.2, 0.1, ValueError),
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Great PR. Would be good to add tests for dt=True, which are compatible with all other discrete-time timebases. https://python-control.readthedocs.io/en/0.9.2/conventions.html

Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Great suggestion. Done.

])
@pytest.mark.parametrize("op", [ct.series, ct.parallel, ct.feedback])
@pytest.mark.parametrize("type", [ct.StateSpace, ct.ss, ct.tf])
def test_composition(dt1, dt2, dt3, op, type):
# Define the system
A, B, C, D = [[1, 1], [0, 1]], [[0], [1]], [[1, 0]], 0
sys1 = ct.StateSpace(A, B, C, D, dt1)
sys2 = ct.StateSpace(A, B, C, D, dt2)

# Convert to the desired form
sys1 = type(sys1)
sys2 = type(sys2)

if inspect.isclass(dt3) and issubclass(dt3, Exception):
with pytest.raises(dt3, match="incompatible timebases"):
sys3 = op(sys1, sys2)
else:
sys3 = op(sys1, sys2)
assert sys3.dt == dt3


@pytest.mark.parametrize("dt", [None, 0, 0.1])
def test_composition_override(dt):
# Define the system
A, B, C, D = [[1, 1], [0, 1]], [[0], [1]], [[1, 0]], 0
sys1 = ct.ss(A, B, C, D, None, inputs='u1', outputs='y1')
sys2 = ct.ss(A, B, C, D, None, inputs='y1', outputs='y2')

# Show that we can override the type
sys3 = ct.interconnect([sys1, sys2], inputs='u1', outputs='y2', dt=dt)
assert sys3.dt == dt

# Overriding the type with an inconsistent type generates an error
sys1 = ct.StateSpace(A, B, C, D, 0.1, inputs='u1', outputs='y1')
if dt != 0.1 and dt is not None:
with pytest.raises(ValueError, match="incompatible timebases"):
sys3 = ct.interconnect(
[sys1, sys2], inputs='u1', outputs='y2', dt=dt)

sys1 = ct.StateSpace(A, B, C, D, 0, inputs='u1', outputs='y1')
if dt != 0 and dt is not None:
with pytest.raises(ValueError, match="incompatible timebases"):
sys3 = ct.interconnect(
[sys1, sys2], inputs='u1', outputs='y2', dt=dt)