'''
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.
'''
#
# Basilisk Scenario Script and Integrated Test
#
# Purpose: Test the validity of a simple exponential atmosphere model.
# Author: Andrew Harris
# Creation Date: Jan 18, 2017
#
import sys, os, inspect
import numpy as np
import math
import csv
import logging
# import general simulation support files
from Basilisk.utilities import SimulationBaseClass
from Basilisk.utilities import unitTestSupport # general support file with common unit test functions
import matplotlib.pyplot as plt
from Basilisk.utilities import macros
from Basilisk.utilities import orbitalMotion
# import simulation related support
from Basilisk.simulation import spacecraftPlus
from Basilisk.utilities import simIncludeGravBody
from Basilisk.simulation import exponentialAtmosphere, simple_nav
from Basilisk.utilities import unitTestSupport, RigidBodyKinematics
#print dir(exponentialAtmosphere)
from Basilisk.simulation import dragDynamicEffector
filename = inspect.getframeinfo(inspect.currentframe()).filename
path = os.path.dirname(os.path.abspath(filename))
# uncomment this line is this test is to be skipped in the global unit test run, adjust message as needed
# @pytest.mark.skipif(conditionstring)
# uncomment this line if this test has an expected failure, adjust message as needed
# @pytest.mark.xfail(True, reason="Previously set sim parameters are not consistent with new formulation\n")
# The following 'parametrize' function decorator provides the parameters and expected results for each
# of the multiple test runs for this test.
# provide a unique test method name, starting with test_
[docs]def test_scenarioDragOrbit():
'''This function is called by the py.test environment.'''
# each test method requires a single assert method to be called
earthCase = "Earth"
marsCase = "Mars"
orb1 = "LPO"
orb2 = "LTO"
showVal = False
testResults = []
testMessage = []
[leoResults, leoMessages] = run(
showVal, orb1, earthCase)
#[gtoResults, gtoMessages] = run(
# showVal, orb2, earthCase)
#[lmoResults, lmoMessages] = run(
#showVal, orb1, marsCase)
#[mtoResults, mtoMessages] = run(
#showVal, orb2, marsCase)
testResults = leoResults#+gtoResults#+lmoResults+mtoResults
testMessage.append(leoMessages)
#testMessage.append(gtoMessages)
##testMessage.append(lmoMessages)
#testMessage.append(mtoMessages)
assert testResults < 1, testMessage
def expAtmoComp(alt, baseDens, scaleHeight):
dens = baseDens * math.exp(-alt/scaleHeight)
return dens
def cannonballDragComp(dragCoeff, dens, area, vel, att):
dragDir_N = -vel / np.linalg.norm(vel)
dcm_BN = RigidBodyKinematics.MRP2C(att)
dragDir_B = dcm_BN.dot(dragDir_N)
dragForce = 0.5 * dragCoeff * dens * area * np.linalg.norm(vel)**2.0 * dragDir_B
return dragForce
[docs]def run(show_plots, orbitCase, planetCase):
'''Call this routine directly to run the tutorial scenario.'''
testFailCount = 0 # zero unit test result counter
testMessages = [] # create empty array to store test log messages
# Create simulation variable names
simTaskName = "simTask"
simProcessName = "simProcess"
# Create a sim module as an empty container
scSim = SimulationBaseClass.SimBaseClass()
# create the simulation process
dynProcess = scSim.CreateNewProcess(simProcessName)
# create the dynamics task and specify the integration update time
simulationTimeStep = macros.sec2nano(1.0)
dynProcess.addTask(scSim.CreateNewTask(simTaskName, simulationTimeStep))
# Initialize new atmosphere and drag model, add them to task
newAtmo = exponentialAtmosphere.ExponentialAtmosphere()
atmoTaskName = "atmosphere"
newAtmo.ModelTag = "ExpAtmo"
projArea = 10.0 # Set drag area in m^2
dragCoeff = 2.2 # Set drag ceofficient
dragEffector = dragDynamicEffector.DragDynamicEffector()
dragEffector.ModelTag = "DragEff"
dragEffectorTaskName = "drag"
dragEffector.coreParams.projectedArea = projArea
dragEffector.coreParams.dragCoeff = dragCoeff
dragEffector.coreParams.comOffset = [1., 0., 0.]
dragEffector.navAttInMsgName = 'nav_att_out'
dynProcess.addTask(scSim.CreateNewTask(atmoTaskName, simulationTimeStep))
dynProcess.addTask(scSim.CreateNewTask(dragEffectorTaskName, simulationTimeStep))
scSim.AddModelToTask(atmoTaskName, newAtmo)
#
# setup the simulation tasks/objects
#
# initialize spacecraftPlus object and set properties
scObject = spacecraftPlus.SpacecraftPlus()
scObject.ModelTag = "spacecraftBody"
simpleNavObj = simple_nav.SimpleNav()
simpleNavObj.inputStateName = scObject.scStateOutMsgName
simpleNavObj.outputAttName = 'nav_att_out'
scSim.AddModelToTask(simTaskName, simpleNavObj)
scObject.addDynamicEffector(dragEffector)
# add spacecraftPlus object to the simulation process
scSim.AddModelToTask(simTaskName, scObject)
scSim.AddModelToTask(dragEffectorTaskName, dragEffector)
# clear prior gravitational body and SPICE setup definitions
gravFactory = simIncludeGravBody.gravBodyFactory()
newAtmo.addSpacecraftToModel(scObject.scStateOutMsgName)
dragEffector.setDensityMessage(newAtmo.envOutMsgNames[-1])
if planetCase == "Earth":
planet = gravFactory.createEarth()
elif planetCase == "Mars":
planet = gravFactory.createMars()
planet.isCentralBody = True # ensure this is the central gravitational body
mu = planet.mu
# attach gravity model to spaceCraftPlus
scObject.gravField.gravBodies = spacecraftPlus.GravBodyVector(list(gravFactory.gravBodies.values()))
#
# setup orbit and simulation time
oe = orbitalMotion.ClassicElements()
if planetCase == "Earth":
r_eq = 6371*1000.0
refBaseDens = 1.217
refScaleHeight = 8500.0
elif planetCase == "Mars":
refBaseDens = 0.020
refScaleHeight = 11100.0
r_eq = 3389.5 * 1000.0
else:
return 1, "Test failed- did not initialize planets."
if orbitCase == "LPO":
orbAltMin = 300.0*1000.0
orbAltMax = orbAltMin
elif orbitCase == "LTO":
orbAltMin = 300*1000.0
orbAltMax = 800.0 * 1000.0
newAtmo.planetRadius = r_eq
newAtmo.scaleHeight = refScaleHeight
newAtmo.baseDensity = refBaseDens
rMin = r_eq + orbAltMin
rMax = r_eq + orbAltMax
oe.a = (rMin+rMax)/2.0
oe.e = 1.0 - rMin/oe.a
oe.i = 0.0*macros.D2R
oe.Omega = 0.0*macros.D2R
oe.omega = 0.0*macros.D2R
oe.f = 0.0*macros.D2R
rN, vN = orbitalMotion.elem2rv(mu, oe)
oe = orbitalMotion.rv2elem(mu, rN, vN) # this stores consistent initial orbit elements
# with circular or equatorial orbit, some angles are
# arbitrary
# set the simulation time
n = np.sqrt(mu/oe.a/oe.a/oe.a)
P = 2.*np.pi/n
simulationTime = macros.sec2nano(1*P)
#
# Setup data logging before the simulation is initialized
#
numDataPoints = 100
samplingTime = simulationTime // (numDataPoints-1)
scSim.TotalSim.logThisMessage(scObject.scStateOutMsgName, samplingTime)
scSim.TotalSim.logThisMessage(newAtmo.envOutMsgNames[-1], samplingTime)
scSim.TotalSim.logThisMessage(simpleNavObj.outputAttName, samplingTime)
scSim.AddVariableForLogging('DragEff.forceExternal_B', samplingTime, StartIndex=0, StopIndex=2)
#
# initialize Spacecraft States with initialization variables
#
scObject.hub.r_CN_NInit = rN # m - r_CN_N
scObject.hub.v_CN_NInit = vN # m - v_CN_N
#
# initialize Simulation
#
scSim.InitializeSimulation()
#
# configure a simulation stop time time and execute the simulation run
#
scSim.ConfigureStopTime(simulationTime)
scSim.ExecuteSimulation()
#
# retrieve the logged data
#
posData = scSim.pullMessageLogData(scObject.scStateOutMsgName+'.r_BN_N',list(range(3)))
velData = scSim.pullMessageLogData(scObject.scStateOutMsgName+'.v_BN_N',list(range(3)))
attData = scSim.pullMessageLogData(scObject.scStateOutMsgName+'.sigma_BN', list(range(3)))
dragForce = scSim.GetLogVariableData('DragEff.forceExternal_B')
densData = scSim.pullMessageLogData(newAtmo.envOutMsgNames[-1]+'.neutralDensity')
np.set_printoptions(precision=16)
# Compare to expected values
endInd = dragForce.shape[0]
refDragForce = np.zeros([endInd,3])
refDensData = np.zeros([endInd,1])
accuracy = 1e-13
# print planetCase
# print orbitCase
for ind in range(0, endInd-1):
# print "Position data:", posData[ind,1:]
# print "Velocity data:", velData[ind,1:]
# print "Density data:", densData[ind,1]
refDragForce[ind,:] = cannonballDragComp(dragCoeff,densData[ind,1],projArea,velData[ind,1:], attData[ind,1:])
# print "Reference drag data:", refDragForce[ind,:]
# print "Drag Data:", dragForce[ind,1:]
# print ""
# check a vector values
for ind in range(1,endInd-1):
if not unitTestSupport.isArrayEqual(dragForce[ind,:], refDragForce[ind,:],3,accuracy):
testFailCount += 1
testMessages.append(
"FAILED: DragEffector failed force unit test at =" + str(densData[ind, 0] * macros.NANO2SEC) + "sec with a value difference of "+str(np.linalg.norm(dragForce[ind,1:]-refDragForce[ind,:])))
#
# plot the results
#
if show_plots:
plt.close("all") # clears out plots from earlier test runs
# draw the inertial position vector components
plt.figure(1)
fig = plt.gcf()
ax = fig.gca()
ax.ticklabel_format(useOffset=False, style='plain')
for idx in range(1,4):
plt.plot(posData[:, 0]*macros.NANO2SEC/P, posData[:, idx]/1000.,
color=unitTestSupport.getLineColor(idx,3),
label='$r_{BN,'+str(idx)+'}$')
plt.legend(loc='lower right')
plt.xlabel('Time [orbits]')
plt.ylabel('Inertial Position [km]')
# draw orbit in perifocal frame
b = oe.a*np.sqrt(1-oe.e*oe.e)
p = oe.a*(1-oe.e*oe.e)
plt.figure(2,figsize=np.array((1.0, b/oe.a))*4.75,dpi=100)
plt.axis(np.array([-oe.rApoap, oe.rPeriap, -b, b])/1000*1.25)
# draw the planet
fig = plt.gcf()
ax = fig.gca()
planetColor= '#008800'
planetRadius = planet.radEquator/1000
ax.add_artist(plt.Circle((0, 0), planetRadius, color=planetColor))
# draw the actual orbit
rData=[]
fData=[]
for idx in range(0,len(posData)):
oeData = orbitalMotion.rv2elem(mu,posData[idx,1:4],velData[idx,1:4])
rData.append(oeData.rmag)
fData.append(oeData.f + oeData.omega - oe.omega)
plt.plot(rData*np.cos(fData)/1000, rData*np.sin(fData)/1000
,color='#aa0000'
,linewidth = 3.0
)
# draw the full osculating orbit from the initial conditions
fData = np.linspace(0,2*np.pi,100)
rData = []
for idx in range(0,len(fData)):
rData.append(p/(1+oe.e*np.cos(fData[idx])))
plt.plot(rData*np.cos(fData)/1000, rData*np.sin(fData)/1000
,'--'
, color='#555555'
)
plt.xlabel('$i_e$ Cord. [km]')
plt.ylabel('$i_p$ Cord. [km]')
plt.grid()
plt.figure()
fig = plt.gcf()
ax = fig.gca()
ax.ticklabel_format(useOffset=False, style='plain')
smaData = []
for idx in range(0, len(posData)):
oeData = orbitalMotion.rv2elem(mu, posData[idx, 1:4], velData[idx, 1:4])
smaData.append(oeData.a/1000.)
plt.plot(posData[:, 0]*macros.NANO2SEC/P, smaData
,color='#aa0000',
)
plt.xlabel('Time [orbits]')
plt.ylabel('SMA [km]')
plt.figure()
fig = plt.gcf()
ax = fig.gca()
ax.ticklabel_format(useOffset=False, style='sci')
plt.plot( densData[:,0]*macros.NANO2SEC, densData[:,1])
plt.title('Density Data vs. Time')
plt.xlabel('Time')
plt.ylabel('Density in kg/m^3')
plt.show()
plt.close("all")
if testFailCount == 0:
print("PASSED: " + dragEffector.ModelTag)
else:
print("Failed: " + dragEffector.ModelTag)
return testFailCount, testMessages
# close the plots being saved off to avoid over-writing old and new figures
if __name__ == '__main__':
run(True,"LPO","Earth")