#
# 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.
#
r"""
.. raw:: html
<iframe width="560" height="315" src="https://www.youtube.com/embed/AQAcHAmxcaU" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
Overview
--------
Discusses how to use guidance modules to point a particular spacecraft axis towards an Earth
fixed location, Boulder in this example.
This script sets up a 6-DOF spacecraft which is orbiting the Earth.
The script is found in the folder ``basilisk/examples`` and executed by using::
python3 scenarioAttLocPoint.py
The simulation uses :ref:`groundLocation` to create an output message with Boulder's inertial
position. This is fed to the 2D pointing module :ref:`locationPointing` which
directs the 3rd body axis to point towards Boulder.
Illustration of Simulation Results
----------------------------------
::
show_plots = True
The following 2 plots illustrate the 2D pointing error and the external attitude control torque vector components.
.. image:: /_images/Scenarios/scenarioAttLocPoint1.svg
:align: center
.. image:: /_images/Scenarios/scenarioAttLocPoint2.svg
:align: center
"""
#
# Basilisk Scenario Script and Integrated Test
#
# Purpose: Integrated test of the spacecraft(), extForceTorque, simpleNav(),
# locationPoint() modules. Will point a spacecraft axis at an Earth fixed location.
# Author: Hanspeter Schaub
# Creation Date: May 9, 2021
#
import os
import matplotlib.pyplot as plt
import numpy as np
# The path to the location of Basilisk
# Used to get the location of supporting data.
from Basilisk import __path__
# import message declarations
from Basilisk.architecture import messaging
from Basilisk.fswAlgorithms import locationPointing
# import FSW Algorithm related support
from Basilisk.fswAlgorithms import mrpFeedback
from Basilisk.simulation import extForceTorque
from Basilisk.simulation import groundLocation
from Basilisk.simulation import simpleNav
# import simulation related support
from Basilisk.simulation import spacecraft
# import general simulation support files
from Basilisk.utilities import SimulationBaseClass
from Basilisk.utilities import astroFunctions
from Basilisk.utilities import macros
from Basilisk.utilities import orbitalMotion
from Basilisk.utilities import simIncludeGravBody
from Basilisk.utilities import unitTestSupport # general support file with common unit test functions
# attempt to import vizard
from Basilisk.utilities import vizSupport
bskPath = __path__[0]
fileName = os.path.basename(os.path.splitext(__file__)[0])
# Plotting functions
[docs]def plot_attitude_error(timeLineSet, dataSigmaBR):
"""Plot the attitude result."""
plt.figure(1)
fig = plt.gcf()
ax = fig.gca()
vectorData = dataSigmaBR
sNorm = np.array([np.linalg.norm(v) for v in vectorData])
plt.plot(timeLineSet, sNorm,
color=unitTestSupport.getLineColor(1, 3),
)
plt.xlabel('Time [min]')
plt.ylabel(r'Attitude Error Norm $|\sigma_{B/R}|$')
ax.set_yscale('log')
[docs]def plot_control_torque(timeLineSet, dataLr):
"""Plot the control torque response."""
plt.figure(2)
for idx in range(3):
plt.plot(timeLineSet, dataLr[:, idx],
color=unitTestSupport.getLineColor(idx, 3),
label='$L_{r,' + str(idx) + '}$')
plt.legend(loc='lower right')
plt.xlabel('Time [min]')
plt.ylabel('Control Torque $L_r$ [Nm]')
[docs]def plot_rate_error(timeLineSet, dataOmegaBR):
"""Plot the body angular velocity tracking error."""
plt.figure(3)
for idx in range(3):
plt.plot(timeLineSet, dataOmegaBR[:, idx],
color=unitTestSupport.getLineColor(idx, 3),
label=r'$\omega_{BR,' + str(idx) + '}$')
plt.legend(loc='lower right')
plt.xlabel('Time [min]')
plt.ylabel('Rate Tracking Error [rad/s] ')
return
[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
"""
# Create simulation variable names
simTaskName = "simTask"
simProcessName = "simProcess"
# Create a sim module as an empty container
scSim = SimulationBaseClass.SimBaseClass()
# set the simulation time variable used later on
simulationTime = macros.min2nano(20.)
#
# 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))
#
# setup the simulation tasks/objects
#
# initialize spacecraft object and set properties
scObject = spacecraft.Spacecraft()
scObject.ModelTag = "bsk-Sat"
# define the simulation inertia
I = [900., 0., 0.,
0., 800., 0.,
0., 0., 600.]
scObject.hub.mHub = 750.0 # kg - spacecraft mass
scObject.hub.r_BcB_B = [[0.0], [0.0], [0.0]] # m - position vector of body-fixed point B relative to CM
scObject.hub.IHubPntBc_B = unitTestSupport.np2EigenMatrix3d(I)
# add spacecraft object to the simulation process
scSim.AddModelToTask(simTaskName, scObject)
# clear prior gravitational body and SPICE setup definitions
gravFactory = simIncludeGravBody.gravBodyFactory()
# setup Earth Gravity Body
earth = gravFactory.createEarth()
earth.isCentralBody = True # ensure this is the central gravitational body
mu = earth.mu
# attach gravity model to spacecraft
gravFactory.addBodiesTo(scObject)
#
# initialize Spacecraft States with initialization variables
#
# setup the orbit using classical orbit elements
oe = orbitalMotion.ClassicElements()
oe.a = (6378 + 600)*1000. # meters
oe.e = 0.1
oe.i = 63.3 * macros.D2R
oe.Omega = 88.2 * macros.D2R
oe.omega = 347.8 * macros.D2R
oe.f = 135.3 * macros.D2R
rN, vN = orbitalMotion.elem2rv(mu, oe)
scObject.hub.r_CN_NInit = rN # m - r_CN_N
scObject.hub.v_CN_NInit = vN # m/s - v_CN_N
scObject.hub.sigma_BNInit = [[0.1], [0.2], [-0.3]] # sigma_BN_B
scObject.hub.omega_BN_BInit = [[0.001], [-0.01], [0.03]] # rad/s - omega_BN_B
# setup extForceTorque module
# the control torque is read in through the messaging system
extFTObject = extForceTorque.ExtForceTorque()
extFTObject.ModelTag = "externalDisturbance"
# use the input flag to determine which external torque should be applied
# Note that all variables are initialized to zero. Thus, not setting this
# vector would leave it's components all zero for the simulation.
scObject.addDynamicEffector(extFTObject)
scSim.AddModelToTask(simTaskName, extFTObject)
# add the simple Navigation sensor module. This sets the SC attitude, rate, position
# velocity navigation message
sNavObject = simpleNav.SimpleNav()
sNavObject.ModelTag = "SimpleNavigation"
scSim.AddModelToTask(simTaskName, sNavObject)
sNavObject.scStateInMsg.subscribeTo(scObject.scStateOutMsg)
# Create the ground location
groundStation = groundLocation.GroundLocation()
groundStation.ModelTag = "BoulderGroundStation"
groundStation.planetRadius = astroFunctions.E_radius*1e3 # meters
groundStation.specifyLocation(np.radians(40.009971), np.radians(-105.243895), 1624)
groundStation.minimumElevation = np.radians(10.)
groundStation.maximumRange = 1e9 # meters
groundStation.addSpacecraftToModel(scObject.scStateOutMsg)
scSim.AddModelToTask(simTaskName, groundStation)
#
# setup the FSW algorithm tasks
#
# setup Boulder pointing guidance module
locPoint = locationPointing.locationPointing()
locPoint.ModelTag = "locPoint"
scSim.AddModelToTask(simTaskName, locPoint)
locPoint.pHat_B = [0, 0, 1]
locPoint.scAttInMsg.subscribeTo(sNavObject.attOutMsg)
locPoint.useBoresightRateDamping = 1
locPoint.scTransInMsg.subscribeTo(sNavObject.transOutMsg)
locPoint.locationInMsg.subscribeTo(groundStation.currentGroundStateOutMsg)
# grMsgData = messaging.GroundStateMsgPayload()
# grMsg = messaging.GroundStateMsg().write(grMsgData)
# locPoint.locationInMsg.subscribeTo(grMsg)
# setup the MRP Feedback control module
mrpControl = mrpFeedback.mrpFeedback()
mrpControl.ModelTag = "mrpFeedback"
scSim.AddModelToTask(simTaskName, mrpControl)
mrpControl.guidInMsg.subscribeTo(locPoint.attGuidOutMsg)
mrpControl.K = 5.5
mrpControl.Ki = -1 # make value negative to turn off integral feedback
mrpControl.P = 30.0
mrpControl.integralLimit = 2. / mrpControl.Ki * 0.1
# connect torque command to external torque effector
extFTObject.cmdTorqueInMsg.subscribeTo(mrpControl.cmdTorqueOutMsg)
#
# Setup data logging before the simulation is initialized
#
numDataPoints = 100
samplingTime = unitTestSupport.samplingTime(simulationTime, simulationTimeStep, numDataPoints)
mrpLog = mrpControl.cmdTorqueOutMsg.recorder(samplingTime)
attErrLog = locPoint.attGuidOutMsg.recorder(samplingTime)
snAttLog = sNavObject.attOutMsg.recorder(samplingTime)
snTransLog = sNavObject.transOutMsg.recorder(samplingTime)
scSim.AddModelToTask(simTaskName, mrpLog)
scSim.AddModelToTask(simTaskName, attErrLog)
scSim.AddModelToTask(simTaskName, snAttLog)
scSim.AddModelToTask(simTaskName, snTransLog)
#
# create simulation messages
#
# create the FSW vehicle configuration message
vehicleConfigOut = messaging.VehicleConfigMsgPayload()
vehicleConfigOut.ISCPntB_B = I # use the same inertia in the FSW algorithm as in the simulation
configDataMsg = messaging.VehicleConfigMsg().write(vehicleConfigOut)
mrpControl.vehConfigInMsg.subscribeTo(configDataMsg)
# if this scenario is to interface with the BSK Viz, uncomment the following lines
if vizSupport.vizFound:
viz = vizSupport.enableUnityVisualization(scSim, simTaskName, scObject
# , saveFile=fileName
)
vizSupport.addLocation(viz, stationName="Boulder Station"
, parentBodyName=earth.displayName
, r_GP_P=unitTestSupport.EigenVector3d2list(groundStation.r_LP_P_Init)
, fieldOfView=np.radians(160.)
, color='pink'
, range=2000.0*1000 # meters
)
viz.settings.spacecraftSizeMultiplier = 1.5
viz.settings.showLocationCommLines = 1
viz.settings.showLocationCones = 1
viz.settings.showLocationLabels = 1
#
# initialize Simulation
#
scSim.InitializeSimulation()
#
# configure a simulation stop time and execute the simulation run
#
scSim.ConfigureStopTime(simulationTime)
scSim.ExecuteSimulation()
#
# retrieve the logged data
#
dataLr = mrpLog.torqueRequestBody
dataSigmaBR = attErrLog.sigma_BR
dataOmegaBR = attErrLog.omega_BR_B
np.set_printoptions(precision=16)
#
# plot the results
#
timeLineSet = attErrLog.times() * macros.NANO2MIN
plt.close("all") # clears out plots from earlier test runs
plot_attitude_error(timeLineSet, dataSigmaBR)
figureList = {}
pltName = fileName + "1"
figureList[pltName] = plt.figure(1)
plot_control_torque(timeLineSet, dataLr)
pltName = fileName + "2"
figureList[pltName] = plt.figure(2)
plot_rate_error(timeLineSet, dataOmegaBR)
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
)