#
# 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"""
Overview
--------
Demonstrates how to simulate an attitude control scenario without having any gravity
bodies present. In essence, the 3-U cube-sat spacecraft is hovering in deep space. The goal is to
stabilize the tumble of a spacecraft and point it towards a fixed inertial direction.
This script sets up a 6-DOF spacecraft which is hovering in deep space. The scenario duplicates
the scenario in :ref:`scenarioAttitudeFeedback` without adding
Earth gravity body to the simulation.
The script is found in the folder ``basilisk/examples`` and executed by using::
python3 scenarioAttitudeFeedbackNoEarth.py
When the simulation completes 3 plots are shown for the MRP attitude history, the rate
tracking errors, as well as the control torque vector.
The simulation layout is shown in the following illustration. A single simulation process is created
which contains both the spacecraft simulation modules, as well as the Flight Software (FSW) algorithm
modules.
.. image:: /_images/static/test_scenarioAttitudeFeedbackNoEarth.svg
:align: center
The spacecraft simulation is identical to :ref:`scenarioAttitudeFeedback`.
The primary difference is that the gravity body is not included.
Illustration of Simulation Results
----------------------------------
The following simulation runs should output identical results to the scenario runs in
:ref:`scenarioAttitudeFeedback` as the attitude pointing goal
is an inertial orientation, and thus independent of the satellite being in Earth orbit or
hovering in deep space.
::
show_plots = True, useUnmodeledTorque = False, useIntGain = False, useKnownTorque = False
.. image:: /_images/Scenarios/scenarioAttitudeFeedbackNoEarth1000.svg
:align: center
.. image:: /_images/Scenarios/scenarioAttitudeFeedbackNoEarth2000.svg
:align: center
::
show_plots = True, useUnmodeledTorque = True, useIntGain = False, useKnownTorque = False
.. image:: /_images/Scenarios/scenarioAttitudeFeedbackNoEarth1100.svg
:align: center
.. image:: /_images/Scenarios/scenarioAttitudeFeedbackNoEarth2100.svg
:align: center
::
show_plots = True, useUnmodeledTorque = True, useIntGain = True, useKnownTorque = False
.. image:: /_images/Scenarios/scenarioAttitudeFeedbackNoEarth1110.svg
:align: center
.. image:: /_images/Scenarios/scenarioAttitudeFeedbackNoEarth2110.svg
:align: center
::
show_plots = True, useUnmodeledTorque = True, useIntGain = False, useKnownTorque = True
.. image:: /_images/Scenarios/scenarioAttitudeFeedbackNoEarth1101.svg
:align: center
.. image:: /_images/Scenarios/scenarioAttitudeFeedbackNoEarth2101.svg
:align: center
"""
#
# Basilisk Scenario Script and Integrated Test
#
# Purpose: Integrated test of the spacecraft(), extForceTorque, simpleNav() and
# mrpFeedback() modules. Illustrates spacecraft attitude control in deep
# space without a planet or gravity body setup.
# Author: Hanspeter Schaub
# Creation Date: Sept. 13, 2018
#
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 attTrackingError
from Basilisk.fswAlgorithms import inertial3D
# import FSW Algorithm related support
from Basilisk.fswAlgorithms import mrpFeedback
from Basilisk.simulation import extForceTorque
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 macros
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])
[docs]def run(show_plots, useUnmodeledTorque, useIntGain, useKnownTorque):
"""
The scenarios can be run with the followings setups parameters:
Args:
show_plots (bool): Determines if the script should display plots
useUnmodeledTorque (bool): Specify if an external torque should be included
useIntGain (bool): Specify if the feedback control uses an integral feedback term
useKnownTorque (bool): Specify if the external torque is feed forward in the contro
"""
# 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(10.)
#
# create the simulation process
#
dynProcess = scSim.CreateNewProcess(simProcessName)
# create the dynamics task and specify the integration update time
simulationTimeStep = macros.sec2nano(.1)
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)
# 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.
if useUnmodeledTorque:
extFTObject.extTorquePntB_B = [[0.25], [-0.25], [0.1]]
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)
#
# setup the FSW algorithm tasks
#
# setup inertial3D guidance module
inertial3DObj = inertial3D.inertial3D()
inertial3DObj.ModelTag = "inertial3D"
scSim.AddModelToTask(simTaskName, inertial3DObj)
inertial3DObj.sigma_R0N = [0., 0., 0.] # set the desired inertial orientation
# setup the attitude tracking error evaluation module
attError = attTrackingError.attTrackingError()
attError.ModelTag = "attErrorInertial3D"
scSim.AddModelToTask(simTaskName, attError)
# setup the MRP Feedback control module
mrpControl = mrpFeedback.mrpFeedback()
mrpControl.ModelTag = "mrpFeedback"
scSim.AddModelToTask(simTaskName, mrpControl)
mrpControl.K = 3.5
if useIntGain:
mrpControl.Ki = 0.0002 # make value negative to turn off integral feedback
else:
mrpControl.Ki = -1 # make value negative to turn off integral feedback
mrpControl.P = 30.0
mrpControl.integralLimit = 2. / mrpControl.Ki * 0.1
if useKnownTorque:
mrpControl.knownTorquePntB_B = [0.25, -0.25, 0.1]
#
# Setup data logging before the simulation is initialized
#
numDataPoints = 100
samplingTime = unitTestSupport.samplingTime(simulationTime, simulationTimeStep, numDataPoints)
attErrorLog = attError.attGuidOutMsg.recorder(samplingTime)
mrpLog = mrpControl.cmdTorqueOutMsg.recorder(samplingTime)
scSim.AddModelToTask(simTaskName, attErrorLog)
scSim.AddModelToTask(simTaskName, mrpLog)
#
# 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)
# The primary difference is that the gravity body is not included.
# When initializing the spacecraft states, only the attitude states must be set. The position and velocity
# states are initialized automatically to zero.
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
# if this scenario is to interface with the BSK Viz, uncomment the following lines
viz = vizSupport.enableUnityVisualization(scSim, simTaskName, scObject
, modelDictionaryKeyList="3USat"
# , saveFile=fileName
)
#
# connect the messages to the modules
#
sNavObject.scStateInMsg.subscribeTo(scObject.scStateOutMsg)
attError.attNavInMsg.subscribeTo(sNavObject.attOutMsg)
attError.attRefInMsg.subscribeTo(inertial3DObj.attRefOutMsg)
mrpControl.guidInMsg.subscribeTo(attError.attGuidOutMsg)
extFTObject.cmdTorqueInMsg.subscribeTo(mrpControl.cmdTorqueOutMsg)
mrpControl.vehConfigInMsg.subscribeTo(configDataMsg)
#
# 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 = attErrorLog.sigma_BR
dataOmegaBR = attErrorLog.omega_BR_B
timeAxis = attErrorLog.times()
np.set_printoptions(precision=16)
#
# plot the results
#
plt.close("all") # clears out plots from earlier test runs
plt.figure(1)
for idx in range(3):
plt.plot(timeAxis * macros.NANO2MIN, dataSigmaBR[:, idx],
color=unitTestSupport.getLineColor(idx, 3),
label=r'$\sigma_' + str(idx) + '$')
plt.legend(loc='lower right')
plt.xlabel('Time [min]')
plt.ylabel(r'Attitude Error $\sigma_{B/R}$')
figureList = {}
pltName = fileName + "1" + str(int(useUnmodeledTorque)) + str(int(useIntGain))+ str(int(useKnownTorque))
figureList[pltName] = plt.figure(1)
plt.figure(2)
for idx in range(3):
plt.plot(timeAxis * macros.NANO2MIN, 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]')
pltName = fileName + "2" + str(int(useUnmodeledTorque)) + str(int(useIntGain)) + str(int(useKnownTorque))
figureList[pltName] = plt.figure(2)
plt.figure(3)
for idx in range(3):
plt.plot(timeAxis * macros.NANO2MIN, 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] ')
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
False, # useUnmodeledTorque
False, # useIntGain
False # useKnownTorque
)