# ISC License
#
# Copyright (c) 2016, Autonomous Vehicle Systems Lab, University of Colorado at Boulder
#
# Permission to use, copy, modify, and/or distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
import inspect
import os
import matplotlib.pyplot as plt
import numpy as np
import pytest
filename = inspect.getframeinfo(inspect.currentframe()).filename
path = os.path.dirname(os.path.abspath(filename))
from Basilisk.utilities import simHelpers
from Basilisk.utilities import SimulationBaseClass
from Basilisk.utilities import unitTestSupport # general support file with common unit test functions
from Basilisk.simulation import spacecraft
from Basilisk.simulation import sphericalPendulum
from Basilisk.utilities import simIncludeGravBody
from Basilisk.utilities import orbitalMotion
from Basilisk.utilities import macros
from Basilisk.utilities import pythonVariableLogger
from Basilisk.simulation import fuelTank
from Basilisk.simulation import thrusterDynamicEffector
from Basilisk.utilities import simIncludeThruster
from Basilisk.architecture import messaging
from Basilisk.architecture.bskLogging import BasiliskError
[docs]
@pytest.mark.parametrize("useFlag, testCase", [
(False, 1),
(False, 2),
(False,3),
(False, 4),
(False, 5)
])
# provide a unique test method name, starting with test_
def test_scenarioSphericalPendulum(show_plots, useFlag, testCase):
"""This function is called by the py.test environment."""
# each test method requires a single assert method to be called
[testResults, testMessage] = sphericalPendulumTest(show_plots, useFlag, testCase)
assert testResults < 1, testMessage
[docs]
def sphericalPendulumTest(show_plots, useFlag,testCase):
"""Call this routine directly to run the test scenario."""
testFailCount = 0 # zero unit test result counter
testMessages = [] # create empty array to store test log messages
if testCase == 1 or testCase == 3 or testCase == 4 or testCase == 5:
timeStep = 0.01
if testCase == 2:
timeStep = 0.001
simTaskName = "simTask"
simProcessName = "simProcess"
# create simulation
scSim=SimulationBaseClass.SimBaseClass()
# close possible other simulation
#crete a dynamical process
dynProcess = scSim.CreateNewProcess(simProcessName)
simulationTimeStep = macros.sec2nano(timeStep)
# add task to the dynamical process
dynProcess.addTask(scSim.CreateNewTask(simTaskName, simulationTimeStep))
# create spacecraft object
scObject = spacecraft.Spacecraft()
scObject.ModelTag = "spacecraftBody"
scSim.AddModelToTask(simTaskName, scObject)
# cases 4 and 5 add fuel-slosh damping (isotropic, anisotropic) to check energy dissipation
if testCase == 4:
dampingMatrix = [[10.0, 0.0, 0.0], [0.0, 10.0, 0.0], [0.0, 0.0, 10.0]] # N*s/m
elif testCase == 5:
dampingMatrix = [[50.0, 0.0, 0.0], [0.0, 0.0, 0.0], [0.0, 0.0, 0.0]] # N*s/m
else:
dampingMatrix = [[0.0, 0.0, 0.0], [0.0, 0.0, 0.0], [0.0, 0.0, 0.0]] # N*s/m
# Pendulum 1
scSim.pendulum1 = sphericalPendulum.SphericalPendulum()
# Define Variables for pendulum 1
scSim.pendulum1.pendulumRadius = 0.3 # m/s
scSim.pendulum1.d = [[0.1], [0.1], [0.1]] # m
scSim.pendulum1.D = dampingMatrix # N*s/m
scSim.pendulum1.phiDotInit = 0.01 # rad/s
scSim.pendulum1.thetaDotInit = 0.05 # rad/s
scSim.pendulum1.massInit = 20.0 # kg
scSim.pendulum1.pHat_01=[[np.sqrt(2)/2], [0] , [np.sqrt(2)/2]] # first unit vector of the Pendulum frame
scSim.pendulum1.pHat_02=[[0],[1],[0]] # second unit vector of the Pendulum frame
scSim.pendulum1.pHat_03=[[-np.sqrt(2)/2],[0],[np.sqrt(2)/2]] # third unit vector of the Pendulum frame
# Pendulum 2
scSim.pendulum2 = sphericalPendulum.SphericalPendulum()
# Define Variables for pendulum 2
scSim.pendulum2.pendulumRadius = 0.4 # m/s
scSim.pendulum2.d = [[0.1], [0.1], [0.1]] # m
scSim.pendulum2.D = dampingMatrix # N*s/m
scSim.pendulum2.phiDotInit = 0.1 # rad/s
scSim.pendulum2.thetaDotInit = 0.5 # rad/s
scSim.pendulum2.massInit =40.0 # kg
# Pendulum frame same as Body frame
if testCase == 3:
# add thruster devices
thFactory = simIncludeThruster.thrusterFactory()
thFactory.create('MOOG_Monarc_445',
[1,0,0], # location in S frame
[0,1,0] # direction in S frame
)
# create thruster object container and tie to spacecraft object
thrustersDynamicEffector = thrusterDynamicEffector.ThrusterDynamicEffector()
thFactory.addToSpacecraft("Thrusters",
thrustersDynamicEffector,
scObject)
scSim.fuelTankStateEffector = fuelTank.FuelTank()
tankModel = fuelTank.FuelTankModelConstantVolume()
scSim.fuelTankStateEffector.setTankModel(tankModel)
tankModel.propMassInit = 40.0
tankModel.r_TcT_TInit = [[0.0],[0.0],[0.0]]
scSim.fuelTankStateEffector.setR_TB_B([[0.0],[0.0],[0.0]]) # [m]
tankModel.radiusTankInit = 46.0 / 2.0 / 3.2808399 / 12.0
# Add tank and thruster
scObject.addStateEffector(scSim.fuelTankStateEffector)
scSim.fuelTankStateEffector.addThrusterSet(thrustersDynamicEffector)
# set thruster commands
ThrustMessage = messaging.THRArrayOnTimeCmdMsgPayload()
ThrustMessage.OnTimeRequest = [5.0]
thrCmdMsg = messaging.THRArrayOnTimeCmdMsg().write(ThrustMessage)
thrustersDynamicEffector.cmdsInMsg.subscribeTo(thrCmdMsg)
# Add test module to runtime call list
scSim.AddModelToTask(simTaskName, scSim.fuelTankStateEffector)
scSim.AddModelToTask(simTaskName, thrustersDynamicEffector)
fuelLog = scSim.fuelTankStateEffector.fuelTankOutMsg.recorder()
scSim.AddModelToTask(simTaskName, fuelLog)
# Add particles to tank to activate mass depletion
scSim.fuelTankStateEffector.pushFuelSloshParticle(scSim.pendulum1)
scSim.fuelTankStateEffector.pushFuelSloshParticle(scSim.pendulum2)
# define hub properties
scObject.hub.mHub = 1500 # kg
scObject.hub.r_BcB_B = [[1.0], [0.5], [0.1]] # m
scObject.hub.IHubPntBc_B = [[900.0, 0.0, 0.0], [0.0, 800.0, 0.0], [0.0, 0.0, 600.0]] # kg*m^2
scObject.hub.sigma_BNInit = [[0.0], [0.0], [0.0]] # rad
scObject.hub.omega_BN_BInit = [[1.0], [0.5], [0.1]] # rad/s
# Add fuel slosh to spacecraft
scObject.addStateEffector(scSim.pendulum1)
scObject.addStateEffector(scSim.pendulum2)
# call for a fresh copy of the gravitational body factory
gravFactory = simIncludeGravBody.gravBodyFactory()
planet = gravFactory.createEarth()
planet.isCentralBody = True # ensure this is the central gravitational body
planetRadius = planet.radEquator
mu = planet.mu
# attach gravity to the spacecraft
scObject.gravField.gravBodies = spacecraft.GravBodyVector(list(gravFactory.gravBodies.values()))
# initialize orbital elements
oe = orbitalMotion.ClassicElements()
oe.a=6700.0*1000
oe.e=0.01
oe.omega=100.0*macros.D2R
oe.Omega=100.0*macros.D2R
oe.i=30.0*macros.D2R
oe.f=0.0
# convert them in position and velocity
rN, vN = orbitalMotion.elem2rv(mu, oe)
# attach the state to the spacecraft
scObject.hub.r_CN_NInit = rN # m - r_BN_N
scObject.hub.v_CN_NInit = vN # m/s - v_BN_N
simulationTime = macros.sec2nano(10)
#
# Setup data logging before the simulation is initialized
#
numDataPoints = 100
samplingTime = simHelpers.samplingTime(simulationTime, simulationTimeStep, numDataPoints)
dataLog = scObject.scStateOutMsg.recorder(samplingTime)
scSim.AddModelToTask(simTaskName, dataLog)
# initialize Simulation: This function clears the simulation log, and runs the self_init()
# cross_init() and reset() routines on each module.
# If the routine InitializeSimulationAndDiscover() is run instead of InitializeSimulation(),
# then the all messages are auto-discovered that are shared across different BSK threads.
#
scObjectLog = scObject.logger(["totOrbAngMomPntN_N", "totRotAngMomPntC_N", "totOrbEnergy", "totRotEnergy"])
scSim.AddModelToTask(simTaskName, scObjectLog)
if testCase == 3:
stateLog = pythonVariableLogger.PythonVariableLogger({
"sphericalPendulumMass1": lambda _: scObject.dynManager.getStateObject(scSim.pendulum1.nameOfMassState).getState(),
"sphericalPendulumMass2": lambda _: scObject.dynManager.getStateObject(scSim.pendulum2.nameOfMassState).getState(),
})
scSim.AddModelToTask(simTaskName, stateLog)
scSim.InitializeSimulation()
#
# configure a simulation stop time and execute the simulation run
#
scSim.ConfigureStopTime(simulationTime)
scSim.ExecuteSimulation()
if testCase == 3:
fuelMass = fuelLog.fuelMass
fuelMassDot = fuelLog.fuelMassDot
mass1Out = simHelpers.addTimeColumn(stateLog.times(), stateLog.sphericalPendulumMass1)
mass2Out = simHelpers.addTimeColumn(stateLog.times(), stateLog.sphericalPendulumMass2)
# request energy and momentum
orbAngMom_N = simHelpers.addTimeColumn(scObjectLog.times(), scObjectLog.totOrbAngMomPntN_N)
rotAngMom_N = simHelpers.addTimeColumn(scObjectLog.times(), scObjectLog.totRotAngMomPntC_N)
rotEnergy = simHelpers.addTimeColumn(scObjectLog.times(), scObjectLog.totRotEnergy)
orbEnergy = simHelpers.addTimeColumn(scObjectLog.times(), scObjectLog.totOrbEnergy)
if timeStep == 0.01:
testCaseName = "OneHundredth"
if timeStep == 0.001:
testCaseName = "OneThousandth"
plt.close("all") # clears out plots from earlier test runs
if testCase == 1 or testCase == 2:
plt.figure(1,figsize=(5,4))
plt.plot(orbAngMom_N[:,0]*1e-9, (orbAngMom_N[:,1] - orbAngMom_N[0,1])/orbAngMom_N[0,1], orbAngMom_N[:,0]*1e-9, (orbAngMom_N[:,2] - orbAngMom_N[0,2])/orbAngMom_N[0,2], orbAngMom_N[:,0]*1e-9, (orbAngMom_N[:,3] - orbAngMom_N[0,3])/orbAngMom_N[0,3])
plt.xlabel('Time (s)')
plt.ylabel('Relative Orbital Angular Momentum Variation')
simHelpers.writeFigureLaTeX("ChangeInOrbitalAngularMomentum" + testCaseName, "Change in Orbital Angular Momentum " + testCaseName, plt, r"width=0.8\textwidth", path)
plt.figure(2,figsize=(5,4))
plt.plot(orbEnergy[:,0]*1e-9, (orbEnergy[:,1] - orbEnergy[0,1])/orbEnergy[0,1])
plt.xlabel('Time (s)')
plt.ylabel('Relative Orbital Energy Variation')
simHelpers.writeFigureLaTeX("ChangeInOrbitalEnergy" + testCaseName, "Change in Orbital Energy " + testCaseName, plt, r"width=0.8\textwidth", path)
plt.figure(3,figsize=(5,4))
plt.plot(rotAngMom_N[:,0]*1e-9, (rotAngMom_N[:,1] - rotAngMom_N[0,1])/rotAngMom_N[0,1], rotAngMom_N[:,0]*1e-9, (rotAngMom_N[:,2] - rotAngMom_N[0,2])/rotAngMom_N[0,2], rotAngMom_N[:,0]*1e-9, (rotAngMom_N[:,3] - rotAngMom_N[0,3])/rotAngMom_N[0,3])
plt.xlabel('Time (s)')
plt.ylabel('Relative Rotational Angular Momentum Variation')
simHelpers.writeFigureLaTeX("ChangeInRotationalAngularMomentum" + testCaseName, "Change in Rotational Angular Momentum " + testCaseName, plt, r"width=0.8\textwidth", path)
plt.figure(4,figsize=(5,4))
plt.plot(rotEnergy[:,0]*1e-9, (rotEnergy[:,1] - rotEnergy[0,1])/rotEnergy[0,1])
plt.xlabel('Time (s)')
plt.ylabel('Relative Rotational Energy Variation')
simHelpers.writeFigureLaTeX("ChangeInRotationalEnergy" + testCaseName, "Change in Rotational Energy " + testCaseName, plt, r"width=0.8\textwidth", path)
if testCase == 3:
plt.figure()
plt.plot(fuelLog.times()*1e-9, fuelMass)
plt.title("Tank Fuel Mass")
plt.figure()
plt.plot(fuelLog.times()*1e-9, fuelMassDot)
plt.title("Tank Fuel Mass Dot")
plt.figure()
plt.plot(mass1Out[:,0]*1e-9, mass1Out[:,1])
plt.title("Fuel Particle 1 Mass")
plt.figure()
plt.plot(mass2Out[:,0]*1e-9, mass2Out[:,1])
plt.title("Fuel Particle 2 Mass")
mDotFuel = -0.19392039093
mDotParicle1True = mDotFuel*(20./100.)
mDotParicle2True = mDotFuel*(40./100.)
mDotParicle1Data = [0,(mass1Out[2,1] - mass1Out[1,1])/((mass1Out[2,0] - mass1Out[1,0])*1e-9)]
mDotParicle2Data = [0,(mass2Out[2,1] - mass2Out[1,1])/((mass2Out[2,0] - mass2Out[1,0])*1e-9)]
if show_plots:
plt.show()
plt.close('all')
if testCase != 3:
accuracy = 1e-8
for k in range(len((rotAngMom_N[:,1]))):
if abs((rotAngMom_N[k,1] - rotAngMom_N[0,1])/rotAngMom_N[0,1])>accuracy:
testFailCount += 1
testMessages.append("FAILED: SphericalPendulum does not conserve Rotational Angular Momentum around x axes (timeStep={}s)".format(timeStep))
if abs((rotAngMom_N[k,2] - rotAngMom_N[0,2])/rotAngMom_N[0,2])>accuracy:
testFailCount += 1
testMessages.append("FAILED: SphericalPendulum does not conserve Rotational Angular Momentum around y axes (timeStep={}s)".format(timeStep))
if abs((rotAngMom_N[k,3] - rotAngMom_N[0,3])/rotAngMom_N[0,3])>accuracy:
testFailCount += 1
testMessages.append("FAILED: SphericalPendulum does not conserve Rotational Angular Momentum around z axes (timeStep={}s)".format(timeStep))
if abs((orbAngMom_N[k,1] - orbAngMom_N[0,1])/orbAngMom_N[0,1])>accuracy:
testFailCount += 1
testMessages.append("FAILED: SphericalPendulum does not conserve Orbital Angular Momentum around x axes (timeStep={}s)".format(timeStep))
if abs((orbAngMom_N[k,2] - orbAngMom_N[0,2])/orbAngMom_N[0,2])>accuracy:
testFailCount += 1
testMessages.append("FAILED: SphericalPendulum does not conserve Orbital Angular Momentum around y axes (timeStep={}s)".format(timeStep))
if abs((orbAngMom_N[k,3] - orbAngMom_N[0,3])/orbAngMom_N[0,3])>accuracy:
testFailCount += 1
testMessages.append("FAILED: SphericalPendulum does not conserve Orbital Angular Momentum around z axes (timeStep={}s)".format(timeStep))
# Rotational energy is conserved only without damping; the damped cases 4 and 5 dissipate it (checked below).
if (testCase == 1 or testCase == 2) and abs((rotEnergy[k,1] - rotEnergy[0,1])/rotEnergy[0,1])>accuracy:
testFailCount += 1
testMessages.append("FAILED: SphericalPendulum does not conserve Rotational Energy (timeStep={}s)".format(timeStep))
if abs((orbEnergy[k,1] - orbEnergy[0,1])/orbEnergy[0,1])>accuracy:
testFailCount += 1
testMessages.append("FAILED: SphericalPendulum does not conserve Orbital Energy (timeStep={}s)".format(timeStep))
if testCase == 3:
accuracy = 1e-4
if not unitTestSupport.isDoubleEqual(mDotParicle1Data[1],mDotParicle1True,accuracy):
testFailCount += 1
testMessages.append("FAILED: Linear Spring Mass Damper unit test failed mass 1 dot test")
if not unitTestSupport.isDoubleEqual(mDotParicle2Data[1],mDotParicle2True,accuracy):
testFailCount += 1
testMessages.append("FAILED: Linear Spring Mass Damper unit test failed mass 2 dot test")
if testCase == 4 or testCase == 5:
E = rotEnergy[:, 1]
if not np.all(np.isfinite(E)):
testFailCount += 1
testMessages.append("FAILED: SphericalPendulum damping produced non-finite rotational energy")
else:
E0 = E[0]
# A physical damper removes energy: require a clear net loss.
netLoss = (E0 - E[-1]) / E0
if netLoss < 1.0e-3:
testFailCount += 1
testMessages.append("FAILED: SphericalPendulum damping did not dissipate rotational "
"energy (net loss {:.3e}, expected > 1e-3)".format(netLoss))
# A physical damper cannot increase energy between samples; allow roundoff-level noise.
maxStepRiseTolerance = 1.0e-10 # [-]
maxStepRise = np.max(np.diff(E)) / E0
if maxStepRise > maxStepRiseTolerance:
testFailCount += 1
testMessages.append("FAILED: SphericalPendulum damping injected rotational energy "
"(maximum normalized step rise {:.3e}, expected <= {:.1e})"
.format(maxStepRise, maxStepRiseTolerance))
if testFailCount == 0:
print("PASSED ")
else:
print(testFailCount)
print(testMessages)
return [testFailCount, ''.join(testMessages)]
def _initializeSphericalPendulumWithDamping(dampingMatrix):
"""Initialize a spacecraft carrying one spherical pendulum with the given damping matrix."""
simulation = SimulationBaseClass.SimBaseClass()
process = simulation.CreateNewProcess("testProcess")
process.addTask(simulation.CreateNewTask("testTask", macros.sec2nano(0.01))) # [s]
spacecraftObject = spacecraft.Spacecraft()
pendulum = sphericalPendulum.SphericalPendulum()
pendulum.pendulumRadius = 0.3 # [m]
pendulum.massInit = 20.0 # [kg]
pendulum.D = dampingMatrix # [N*s/m]
spacecraftObject.addStateEffector(pendulum)
simulation.AddModelToTask("testTask", spacecraftObject)
simulation.InitializeSimulation()
[docs]
@pytest.mark.parametrize("dampingMatrix", [
[[0.0, 0.0, 0.0], [0.0, 0.0, 0.0], [0.0, 0.0, 0.0]],
[[10.0, 0.0, 0.0], [0.0, 10.0, 0.0], [0.0, 0.0, 10.0]],
[[50.0, 0.0, 0.0], [0.0, 0.0, 0.0], [0.0, 0.0, 0.0]],
], ids=["zero", "positive-definite", "singular-positive-semidefinite"])
def test_sphericalPendulumAcceptsValidDampingMatrix(dampingMatrix):
"""Initialization must accept zero and symmetric positive-semidefinite damping."""
_initializeSphericalPendulumWithDamping(dampingMatrix)
[docs]
@pytest.mark.parametrize("dampingMatrix", [
[[1.0, 1.0, 0.0], [0.0, 1.0, 0.0], [0.0, 0.0, 1.0]],
[[1.0, 0.0, 0.0], [0.0, -1.0, 0.0], [0.0, 0.0, 1.0]],
[[1.0, np.nan, 0.0], [0.0, 1.0, 0.0], [0.0, 0.0, 1.0]],
], ids=["nonsymmetric", "indefinite", "nonfinite"])
def test_sphericalPendulumRejectsInvalidDampingMatrix(dampingMatrix):
"""Initialization must reject nonsymmetric, indefinite, or non-finite damping."""
with pytest.raises(BasiliskError, match="D must be symmetric positive semidefinite"):
_initializeSphericalPendulumWithDamping(dampingMatrix)
if __name__ == "__main__":
sphericalPendulumTest(True, # showplots
False, # useFlag
3, # testCase
)