#
# ISC License
#
# Copyright (c) 2021, 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.
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# 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
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# 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.
#
r"""
.. raw:: html
<iframe width="560" height="315" src="https://www.youtube.com/embed/uUomHSGQW3c" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
Overview
--------
Demonstrates how to setup a custom gravity object in Basilisk that is not directly supported by
the ``simIncludeGravBody.py`` file. In this simulation the sun is created using standard values, the Earth
is created using custom values, and the asteroid Itokawa is created with custom values.
.. image:: /_images/static/scenarioCustomGravObject.jpg
:align: center
Further, the Vizard binary file is setup to load up a custom CAD model for the asteroid. The spacecraft
orbit is defined relative to the asteroid. Note, this feature requires :ref:`Vizard <vizard>` version 1.8 or higher.
The script is found in the folder ``basilisk/examples`` and executed by using::
python3 scenarioCustomGravBody.py
The simulation layout is shown in the following illustration. A single simulation process is created
which contains both modules.
.. image:: /_images/static/test_scenarioCustomGravBody.svg
:align: center
:ref:`planetEphemeris` is used to create the planet ephemeris states. The sun is assumed to be stationary,
while Earth is on a circular orbit and Itokawa is on its elliptical heliocentric orbit.
The method ``createCustomGravObject()`` is used to create the BSK grav bodies for both earth and Itokawa.
The earth body is already supported in :ref:`simIncludeGravBody`, but in this script we show how this could
be customized. The gravity body ephemeris states are connected to the :ref:`planetEphemeris` planet
state output messages.
Finally, the recorded states will all be relative to the inertial origin at the sun. :ref:`planetEphemeris` does not
have the ``zeroBase`` capability as :ref:`spiceInterface` has. This script also records the asteroid
states so that the plot is done of the spacecraft motion relative to the asteroid.
The simulation executes and shows a plot of the spacecraft motion relative to the asteroid.
Illustration of Simulation Results
----------------------------------
::
show_plots = True
.. image:: /_images/Scenarios/scenarioCustomGravBody1.svg
:align: center
"""
#
# Basilisk Scenario Script and Integrated Test
#
# Purpose: Basic simulation showing how to setup a custom gravity object
# Author: Hanspeter Schaub
# Creation Date: Feb. 23, 2021
#
import os
import matplotlib.pyplot as plt
from Basilisk.simulation import planetEphemeris
from Basilisk.simulation import spacecraft
from Basilisk.utilities import (SimulationBaseClass, macros, simIncludeGravBody, vizSupport)
from Basilisk.utilities import orbitalMotion
from Basilisk.utilities import unitTestSupport
# The path to the location of Basilisk
# Used to get the location of supporting data.
fileName = os.path.basename(os.path.splitext(__file__)[0])
[docs]def run(show_plots):
"""
The scenarios can be run with the followings setups parameters:
Args:
show_plots (bool): Determines if the script should display plots
"""
path = os.path.dirname(os.path.abspath(__file__))
# 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 simulation time step information
simulationTimeStep = macros.sec2nano(10.0)
simulationTime = macros.min2nano(1120.0)
dynProcess.addTask(scSim.CreateNewTask(simTaskName, simulationTimeStep))
# setup celestial object ephemeris module
gravBodyEphem = planetEphemeris.PlanetEphemeris()
gravBodyEphem.ModelTag = 'planetEphemeris'
scSim.AddModelToTask(simTaskName, gravBodyEphem)
gravBodyEphem.setPlanetNames(planetEphemeris.StringVector(["Itokawa", "earth"]))
# specify orbits of gravitational bodies
oeAsteroid = planetEphemeris.ClassicElementsMsgPayload()
oeAsteroid.a = 1.3241 * orbitalMotion.AU * 1000 # meters
oeAsteroid.e = 0.2801
oeAsteroid.i = 1.6214*macros.D2R
oeAsteroid.Omega = 69.081*macros.D2R
oeAsteroid.omega = 162.82*macros.D2R
oeAsteroid.f = 90.0*macros.D2R
oeEarth = planetEphemeris.ClassicElementsMsgPayload()
oeEarth.a = orbitalMotion.AU * 1000 # meters
oeEarth.e = 0.0167086
oeEarth.i = 7.155 * macros.D2R
oeEarth.Omega = 174.9 * macros.D2R
oeEarth.omega = 288.1 * macros.D2R
oeEarth.f = 270.0 * macros.D2R
# specify celestial object orbit
gravBodyEphem.planetElements = planetEphemeris.classicElementVector([oeAsteroid, oeEarth])
# specify celestial object orientation
gravBodyEphem.rightAscension = planetEphemeris.DoubleVector([0.0 * macros.D2R, 0.0 * macros.D2R])
gravBodyEphem.declination = planetEphemeris.DoubleVector([0.0 * macros.D2R, 0.0 * macros.D2R])
gravBodyEphem.lst0 = planetEphemeris.DoubleVector([0.0 * macros.D2R, 0.0 * macros.D2R])
gravBodyEphem.rotRate = planetEphemeris.DoubleVector(
[360 * macros.D2R / (12.132 * 3600.), 360 * macros.D2R / (24. * 3600.)])
# setup Sun gravity body
gravFactory = simIncludeGravBody.gravBodyFactory()
gravFactory.createSun()
# setup asteroid gravity body
mu = 2.34268 # meters^3/s^2
asteroid = gravFactory.createCustomGravObject("Itokawa", mu)
asteroid.isCentralBody = True # ensure this is the central gravitational body
asteroid.planetBodyInMsg.subscribeTo(gravBodyEphem.planetOutMsgs[0])
# setup Earth gravity Body
earth = gravFactory.createCustomGravObject("earth", 0.3986004415E+15, radEquator=6378136.6)
earth.planetBodyInMsg.subscribeTo(gravBodyEphem.planetOutMsgs[1])
# create SC object
scObject = spacecraft.Spacecraft()
scObject.ModelTag = "bskSat"
gravFactory.addBodiesTo(scObject)
scSim.AddModelToTask(simTaskName, scObject)
# setup orbit initial conditions about the asteroid
oe = orbitalMotion.ClassicElements()
oe.a = 500.0 # meters
oe.e = 0.0001
oe.i = 33.3 * macros.D2R
oe.Omega = 48.2 * macros.D2R
oe.omega = 347.8 * macros.D2R
oe.f = 85.3 * macros.D2R
rN, vN = orbitalMotion.elem2rv(mu, oe)
# To set the spacecraft initial conditions, the following initial position and velocity variables are set:
scObject.hub.r_CN_NInit = rN # m - r_BN_N
scObject.hub.v_CN_NInit = vN # m/s - v_BN_N
#
# Setup data logging before the simulation is initialized
#
numDataPoints = 100
samplingTime = unitTestSupport.samplingTime(simulationTime, simulationTimeStep, numDataPoints)
scRec = scObject.scStateOutMsg.recorder(samplingTime)
astRec = gravBodyEphem.planetOutMsgs[0].recorder(samplingTime)
scSim.AddModelToTask(simTaskName, scRec)
scSim.AddModelToTask(simTaskName, astRec)
# if this scenario is to interface with the BSK Viz, uncomment the following lines
# to save the BSK data to a file, uncomment the saveFile line below
# Note that the gravitational body information is pulled automatically from the spacecraft object(s)
# Even if custom gravitational bodies are added, this information is pulled by the method below
if vizSupport.vizFound:
viz = vizSupport.enableUnityVisualization(scSim, simTaskName, scObject
# , saveFile=fileName
)
viz.settings.showSpacecraftLabels = 1
# load CAD for custom gravity model
vizSupport.createCustomModel(viz,
modelPath=os.path.join(path, "dataForExamples", "Itokawa", "ItokawaHayabusa.obj"),
shader=1,
simBodiesToModify=['Itokawa'],
scale=[962, 962, 962])
# initialize Simulation
scSim.InitializeSimulation()
# configure a simulation stop time and execute the simulation run
scSim.ConfigureStopTime(simulationTime)
scSim.ExecuteSimulation()
# retrieve logged spacecraft position relative to asteroid
posData = scRec.r_BN_N - astRec.PositionVector
#
# plot the results
#
timeAxis = scRec.times() * macros.NANO2HOUR
plt.close("all") # clears out plots from earlier test runs
plt.figure(1)
fig = plt.gcf()
ax = fig.gca()
ax.ticklabel_format(useOffset=False, style='plain')
for idx in range(3):
plt.plot(timeAxis, posData[:, idx] ,
color=unitTestSupport.getLineColor(idx, 3),
label='$r_{BI,' + str(idx) + '}$')
plt.legend(loc='lower right')
plt.xlabel('Time [h]')
plt.ylabel('Itokawa Relative Position [m]')
figureList = {}
pltName = fileName + "1"
figureList[pltName] = plt.figure(1)
if show_plots:
plt.show()
# close the plots being saved off to avoid over-writing old and new figures
plt.close("all")
return figureList
#
# This statement below ensures that the unit test scrip can be run as a
# stand-along python script
#
if __name__ == "__main__":
run(
True # show_plots
)