Skip to content

improve forced_response and its documentation #588

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
bnavigator merged 12 commits into from
Apr 2, 2021
Merged

improve forced_response and its documentation #588

Show file tree
Hide file tree
Changes from 1 commit
Commits
Show all changes
12 commits
Select commit Hold shift + click to select a range
1f51526
update parameter doc and error message for forced_response
bnavigator Mar 24, 2021
2870432
allow T=None with sys.dt=None in forced_response
bnavigator Mar 24, 2021
517b1eb
timeresp: add test system with dt=None
bnavigator Mar 25, 2021
52a3fd4
more docstring fixups
bnavigator Mar 25, 2021
f0d764f
test forced_response omitting parameters as documented
bnavigator Mar 25, 2021
9cac9fa
ensure dlsim output length
bnavigator Mar 26, 2021
7be508b
rework fixture setup for timeresp_test
bnavigator Mar 26, 2021
a72441b
specify tolerance and add comment for markov test
bnavigator Mar 26, 2021
177290c
reactivate the the fast forced_response(U=0) algorithm and test it
bnavigator Mar 26, 2021
ce51d34
cover TF initial condition warning in forced_response
bnavigator Mar 27, 2021
4404169
reallow non zero timevector start
bnavigator Mar 27, 2021
a8b72f5
avoid different realizations with and without slycot
bnavigator Mar 27, 2021
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
Prev Previous commit
Next Next commit
reallow non zero timevector start
  • Loading branch information
@bnavigator
bnavigator committed Apr 1, 2021
commit 44041692eac186a7ac9df31ae98e9f19e7a69067
2 changes: 0 additions & 2 deletions control/tests/timeresp_test.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -685,8 +685,6 @@ def test_forced_response_invalid_c(self, tsystem):
with pytest.raises(ValueError, match="time values must be equally "
"spaced"):
forced_response(tsystem.sys, [0, 0.1, 0.12, 0.4])
with pytest.raises(ValueError, match="must start with 0"):
forced_response(tsystem.sys, [1, 1.1, 1.2, 1.3])

@pytest.mark.parametrize("tsystem", ["siso_dss2"], indirect=True)
def test_forced_response_invalid_d(self, tsystem):
Expand Down
23 changes: 13 additions & 10 deletions control/timeresp.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -209,8 +209,7 @@ def forced_response(sys, T=None, U=0., X0=0., transpose=False,
LTI system to simulate

T : array_like, optional for discrete LTI `sys`
Time steps at which the input is defined; values must be evenly spaced
and start with 0.
Time steps at which the input is defined; values must be evenly spaced.

If None, `U` must be given and `len(U)` time steps of sys.dt are
simulated. If sys.dt is None or True (undetermined time step), a time
Expand Down Expand Up @@ -360,10 +359,10 @@ def forced_response(sys, T=None, U=0., X0=0., transpose=False,
n_steps = T.shape[0] # number of simulation steps

# equally spaced also implies strictly monotonic increase,
dt = T[-1] / (n_steps - 1)
dt = (T[-1] - T[0]) / (n_steps - 1)
if not np.allclose(np.diff(T), dt):
raise ValueError("Parameter ``T`` must start with 0 and time values "
"must be equally spaced.")
raise ValueError("Parameter ``T``: time values must be equally "
"spaced.")

# create X0 if not given, test if X0 has correct shape
X0 = _check_convert_array(X0, [(n_states,), (n_states, 1)],
Expand Down Expand Up @@ -426,6 +425,10 @@ def forced_response(sys, T=None, U=0., X0=0., transpose=False,

else:
# Discrete type system => use SciPy signal processing toolbox

# sp.signal.dlsim assumes T[0] == 0
spT = T - T[0]

if sys.dt is not True and sys.dt is not None:
# Make sure that the time increment is a multiple of sampling time

Expand All @@ -446,10 +449,10 @@ def forced_response(sys, T=None, U=0., X0=0., transpose=False,
# T[-1] - T[0] < sys_dt * decimation * (n_steps - 1)
# due to rounding errors.
# https://github.com/scipyscipy/blob/v1.6.1/scipy/signal/ltisys.py#L3462
scipy_out_samples = int(np.floor(T[-1] / sys_dt)) + 1
scipy_out_samples = int(np.floor(spT[-1] / sys_dt)) + 1
if scipy_out_samples < n_steps:
# parantheses: order of evaluation is important
T[-1] = T[-1] * (n_steps / (T[-1] / sys_dt + 1))
spT[-1] = spT[-1] * (n_steps / (spT[-1] / sys_dt + 1))

else:
sys_dt = dt # For unspecified sampling time, use time incr
Expand All @@ -459,7 +462,8 @@ def forced_response(sys, T=None, U=0., X0=0., transpose=False,

# Use signal processing toolbox for the discrete time simulation
# Transpose the input to match toolbox convention
tout, yout, xout = sp.signal.dlsim(dsys, np.transpose(U), T, X0)
tout, yout, xout = sp.signal.dlsim(dsys, np.transpose(U), spT, X0)
tout = tout + T[0]

if not interpolate:
# If dt is different from sys.dt, resample the output
Expand All @@ -472,8 +476,7 @@ def forced_response(sys, T=None, U=0., X0=0., transpose=False,
xout = np.transpose(xout)
yout = np.transpose(yout)

return _process_time_response(sys, tout[:n_steps], yout[:, :n_steps],
xout[:, :n_steps], transpose=transpose,
return _process_time_response(sys, tout, yout, xout, transpose=transpose,
return_x=return_x, squeeze=squeeze)


Expand Down