#
# ISC License
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# Copyright (c) 2026, Autonomous Vehicle Systems Lab, University of Colorado at Boulder
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# Permission to use, copy, modify, and/or distribute this software for any
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# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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import numpy as np
import numpy.testing as npt
from Basilisk.simulation import spacecraft
from Basilisk.simulation import igbmNoiseStateEffector
from Basilisk.simulation import svIntegrators
from Basilisk.utilities import SimulationBaseClass
from Basilisk.utilities import macros
[docs]
def test_igbmNoiseStateEffector():
"""
Statistical test equivalent to test_meanRevertingNoiseStateEffector.py using the
factor dens = 1 + delta, which follows an IGBM with stationary mean mu and
stationary std sigma_st. Also checks the factor stays strictly positive.
"""
dt = 0.001 # s
tf = 100.0 # s
mean = 1.0
sigmaStationary = 1.0 / 3.0
timeConstant = 0.2
sim = SimulationBaseClass.SimBaseClass()
proc = sim.CreateNewProcess("process")
task_name = "task"
proc.addTask(sim.CreateNewTask(task_name, macros.sec2nano(dt)))
sc_object = spacecraft.Spacecraft()
sim.AddModelToTask(task_name, sc_object)
integrator = svIntegrators.svStochasticIntegratorMayurama(sc_object)
integrator.setRNGSeed(0)
sc_object.setIntegrator(integrator)
effector = igbmNoiseStateEffector.IgbmNoiseStateEffector()
effector.setMean(mean)
effector.setStationaryStd(sigmaStationary)
effector.setTimeConstant(timeConstant)
effector.setStateName("igbmNoiseState")
sc_object.addStateEffector(effector)
sim.InitializeSimulation()
assert effector.getMean() == mean
assert effector.getTimeConstant() == timeConstant
assert effector.getStationaryStd() == sigmaStationary
# Default initial correction is mu - 1 (factor at its mean level).
assert effector.getStateValue() == mean - 1.0
steps = int(tf / dt)
dens = np.zeros(steps)
state_obj = sc_object.dynManager.getStateObject(effector.getStateName())
for i in range(steps):
sim.ConfigureStopTime(macros.sec2nano((i + 1) * dt))
sim.ExecuteSimulation()
dens[i] = 1.0 + state_obj.getState()[0][0]
y = np.asarray(dens)
# Discard an initial transient (a few reversion time constants) before averaging.
burn = int(round(5.0 * timeConstant / dt))
ys = y[burn:]
meanEst = float(np.mean(ys))
varEst = float(np.var(ys, ddof=1))
print(f"mean={meanEst:.4f} (target {mean}) var={varEst:.4f} (target {sigmaStationary**2:.4f})")
# At this small step the sampled factor stays positive; the exact process is positive
# and downstream consumers clamp against the rare negative an explicit step can give.
assert np.all(y > 0.0), "IGBM factor went non-positive"
npt.assert_allclose(meanEst, mean, rtol=0.05, atol=0.02)
npt.assert_allclose(varEst, sigmaStationary**2, rtol=0.30)
[docs]
def test_igbmNoiseStateEffector_rejectsNonPositiveInitialFactor():
"""setStateValue must reject an initial correction <= -1, since the process is only
well-posed from a positive initial factor 1 + delta."""
import pytest
from Basilisk.architecture import bskLogging
effector = igbmNoiseStateEffector.IgbmNoiseStateEffector()
for bad in (-1.0, -1.5):
with pytest.raises(bskLogging.BasiliskError):
effector.setStateValue(bad)
# A correction above -1 (initial factor positive) is accepted.
effector.setStateValue(-0.5)
assert effector.getStateValue() == -0.5
[docs]
def test_igbmNoiseStateEffector_rejectsBadParameters():
"""The parameter setters reject values outside their valid range."""
import pytest
from Basilisk.architecture import bskLogging
effector = igbmNoiseStateEffector.IgbmNoiseStateEffector()
for bad in (0.0, -1.0):
with pytest.raises(bskLogging.BasiliskError):
effector.setMean(bad)
for bad in (0.0, -0.1):
with pytest.raises(bskLogging.BasiliskError):
effector.setTimeConstant(bad)
with pytest.raises(bskLogging.BasiliskError):
effector.setStationaryStd(-0.01)
effector.setMean(2.0); effector.setTimeConstant(0.5); effector.setStationaryStd(0.0)
assert effector.getMean() == 2.0
assert effector.getTimeConstant() == 0.5
assert effector.getStationaryStd() == 0.0
if __name__ == "__main__":
test_igbmNoiseStateEffector()
test_igbmNoiseStateEffector_rejectsNonPositiveInitialFactor()
test_igbmNoiseStateEffector_rejectsBadParameters()