# ISC License
#
# Copyright (c) 2024, 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.
#
# Unit Test Script
# Module Name: linearTranslationNDOF
# Author: Peter Johnson
# Creation Date: March 7, 2024
#
import inspect
import os
import numpy as np
import pytest
import numpy
import matplotlib.pyplot as plt
# plt.rcParams['text.usetex'] = True
filename = inspect.getframeinfo(inspect.currentframe()).filename
path = os.path.dirname(os.path.abspath(filename))
splitPath = path.split('simulation')
from Basilisk.utilities import (
SimulationBaseClass,
macros,
)
from Basilisk.simulation import spacecraft, linearTranslationNDOFStateEffector, gravityEffector
from Basilisk.simulation import linearTranslationOneDOFStateEffector, extForceTorque
from Basilisk.architecture import messaging
from Basilisk.architecture.bskLogging import BasiliskError
[docs]
def randomValidInertia():
r"""Generate a random diagonal inertia tensor that is physically realizable."""
secondMoments = np.random.uniform(2.5, 50.0, 3) # [kg m^2]
principalInertias = np.array([
secondMoments[1] + secondMoments[2],
secondMoments[0] + secondMoments[2],
secondMoments[0] + secondMoments[1]
]) # [kg m^2]
return np.diag(principalInertias)
# 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() # need to update how the RW states are defined
# provide a unique test method name, starting with test_
[docs]
@pytest.mark.parametrize("function", ["translatingBodyNoInput"
, "translatingBodyLockAxis"
, "translatingBodyCommandedForce"])
def test_translatingBody(show_plots, function):
r"""
**Validation Test Description**
This unit test sets up a spacecraft with four single-axis translating rigid bodies attached to a rigid hub. Each
translating body's center of mass is off-center from the translating axis and the position of the axis is arbitrary.
The scenario includes gravity acting on both the spacecraft and the effector.
**Description of Variables Being Tested**
In this file we are checking the principles of conservation of energy and angular momentum. Both the orbital and
rotational energy and angular momentum must be maintained when conservative forces like gravity are present.
Therefore, the values of the variables
- ``finalOrbAngMom``
- ``finalOrbEnergy``
- ``finalRotAngMom``
- ``finalRotEnergy``
against their initial values.
"""
testFunction = globals().get(function)
if testFunction is None:
raise ValueError(f"Function '{function}' not found in global scope")
testFunction(show_plots)
[docs]
def test_translatingBodyOutputMessagesMatchOneDOF():
"""
Verify both output-message vectors against the equivalent one-DOF model.
A single-body N-DOF effector and a one-DOF effector are given identical geometry, mass
properties, and initial states on their own spacecraft in one simulation. The hub starts with a
non-identity attitude and nonzero translational and angular velocity so that every inertial
transformation contributes. The displacement, displacement rate, inertial position, inertial
velocity, attitude, and angular velocity are compared at every step.
"""
timeStep = 0.01 # [s]
unitTestSim = SimulationBaseClass.SimBaseClass()
unitTestSim.SetProgressBar(False)
testProc = unitTestSim.CreateNewProcess("TestProcess")
testProc.addTask(unitTestSim.CreateNewTask("unitTask", macros.sec2nano(timeStep)))
mass = 20.0 # [kg]
k = 100.0 # [N/m]
rhoInit = 0.4 # [m]
rhoDotInit = 0.05 # [m/s]
fHat = [[3.0 / 5.0], [4.0 / 5.0], [0.0]]
r_FcF_F = [[-1.0], [1.0], [0.5]] # [m]
r_F0B_B = [[-1.0], [1.0], [0.0]] # [m]
IPntFc_F = [[50.0, 0.0, 0.0], [0.0, 80.0, 0.0], [0.0, 0.0, 60.0]] # [kg*m^2]
dcm_FB = [[0.0, -1.0, 0.0], [0.0, 0.0, -1.0], [1.0, 0.0, 0.0]]
nDofEffector = linearTranslationNDOFStateEffector.LinearTranslationNDOFStateEffector()
nDofEffector.ModelTag = "translatingBodyNDOF"
body = linearTranslationNDOFStateEffector.TranslatingBody()
body.setMass(mass)
body.setK(k)
body.setC(0.0) # [N*s/m]
body.setRhoInit(rhoInit)
body.setRhoDotInit(rhoDotInit)
body.setFHat_P(fHat)
body.setR_FcF_F(r_FcF_F)
body.setR_F0P_P(r_F0B_B)
body.setIPntFc_F(IPntFc_F)
body.setDCM_FP(dcm_FB)
nDofEffector.addTranslatingBody(body)
oneDofEffector = linearTranslationOneDOFStateEffector.LinearTranslationOneDOFStateEffector()
oneDofEffector.ModelTag = "translatingBodyOneDOF"
oneDofEffector.setMass(mass)
oneDofEffector.setK(k)
oneDofEffector.setC(0.0) # [N*s/m]
oneDofEffector.setRhoInit(rhoInit)
oneDofEffector.setRhoDotInit(rhoDotInit)
oneDofEffector.setFHat_B(fHat)
oneDofEffector.setR_FcF_F(r_FcF_F)
oneDofEffector.setR_F0B_B(r_F0B_B)
oneDofEffector.setIPntFc_F(IPntFc_F)
oneDofEffector.setDCM_FB(dcm_FB)
recorders = []
for effector in (nDofEffector, oneDofEffector):
scObject = spacecraft.Spacecraft()
scObject.ModelTag = "spacecraft" + effector.ModelTag
scObject.hub.mHub = 750.0 # [kg]
scObject.hub.r_BcB_B = [[0.0], [0.0], [1.0]] # [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.r_CN_NInit = [[-4020338.690396649], [7490566.741852513], [5248299.211589362]] # [m]
scObject.hub.v_CN_NInit = [[-5199.77710904224], [-3436.681645356935], [1041.576797498721]] # [m/s]
scObject.hub.sigma_BNInit = [[0.1], [0.2], [-0.3]]
scObject.hub.omega_BN_BInit = [[0.5], [-0.4], [0.6]] # [rad/s]
earthGravBody = gravityEffector.GravBodyData()
earthGravBody.planetName = "earth_planet_data"
earthGravBody.mu = 0.3986004415E+15 # [m^3/s^2]
earthGravBody.isCentralBody = True
scObject.gravField.gravBodies = spacecraft.GravBodyVector([earthGravBody])
scObject.addStateEffector(effector)
unitTestSim.AddModelToTask("unitTask", effector)
unitTestSim.AddModelToTask("unitTask", scObject)
for outMsg, configMsg in ((nDofEffector.translatingBodyOutMsgs[0],
nDofEffector.translatingBodyConfigLogOutMsgs[0]),
(oneDofEffector.translatingBodyOutMsg,
oneDofEffector.translatingBodyConfigLogOutMsg)):
stateRec = outMsg.recorder()
configRec = configMsg.recorder()
unitTestSim.AddModelToTask("unitTask", stateRec)
unitTestSim.AddModelToTask("unitTask", configRec)
recorders.append((stateRec, configRec))
unitTestSim.InitializeSimulation()
unitTestSim.ConfigureStopTime(macros.sec2nano(10 * timeStep))
unitTestSim.ExecuteSimulation()
(nDofState, nDofConfig), (oneDofState, oneDofConfig) = recorders
accuracy = 1e-10
np.testing.assert_allclose(nDofState.rho, oneDofState.rho, rtol=accuracy,
err_msg="Displacement does not match the one-DOF effector.")
np.testing.assert_allclose(nDofState.rhoDot, oneDofState.rhoDot, rtol=accuracy,
err_msg="Displacement rate does not match the one-DOF effector.")
for field in ("r_BN_N", "v_BN_N", "sigma_BN", "omega_BN_B"):
np.testing.assert_allclose(getattr(nDofConfig, field), getattr(oneDofConfig, field),
rtol=accuracy, atol=accuracy,
err_msg=field + " does not match the one-DOF effector.")
[docs]
@pytest.mark.parametrize("segment, shouldRaise", [(1, False), (3, False), (0, True), (4, True)])
def test_translatingBodyDynamicEffectorSegmentBounds(segment, shouldRaise):
"""
Verify that dynamic effectors can attach only to existing translating bodies.
A three-body chain accepts its first and last body numbers and rejects the adjacent values
outside the valid one-based range.
**Test Parameters:**
- segment: [int]
one-based body number supplied to ``addDynamicEffector``
- shouldRaise: [bool]
whether the body number is outside the valid range
"""
effector = linearTranslationNDOFStateEffector.LinearTranslationNDOFStateEffector()
for _ in range(3):
body = linearTranslationNDOFStateEffector.TranslatingBody()
body.setMass(20.0) # [kg]
effector.addTranslatingBody(body)
child = extForceTorque.ExtForceTorque()
if shouldRaise:
with pytest.raises(BasiliskError, match="non-existent translating body"):
effector.addDynamicEffector(child, segment)
else:
effector.addDynamicEffector(child, segment)
[docs]
def test_translatingBodyMassSetterBoundary():
"""Verify that the mass setter accepts zero and rejects a negative mass."""
body = linearTranslationNDOFStateEffector.TranslatingBody()
body.setMass(1.0) # [kg]
body.setMass(0.0) # [kg]
assert body.getMass() == 0.0
with pytest.raises(BasiliskError, match="greater than or equal to 0"):
body.setMass(-1.0) # [kg]
# Axis and mass [kg] of each body in the chain, outward from the hub. A massless body is given zero
# mass and zero inertia explicitly.
X_AXIS = [[1.0], [0.0], [0.0]]
Y_AXIS = [[0.0], [1.0], [0.0]]
Z_AXIS = [[0.0], [0.0], [1.0]]
XY_AXIS = [[1.0], [1.0], [0.0]]
VALIDATION_CHAINS = {
'Valid': [(20.0, X_AXIS), (15.0, Y_AXIS)],
'MasslessJoint': [(0.0, X_AXIS), (20.0, Y_AXIS)],
'MasslessChain': [(0.0, X_AXIS), (0.0, Y_AXIS), (20.0, Z_AXIS)],
'MasslessOutermost': [(20.0, X_AXIS), (0.0, Y_AXIS)],
'CollinearMassless': [(0.0, X_AXIS), (20.0, X_AXIS)],
# pairwise independent axes that collectively span only two dimensions
'CoplanarMassless': [(0.0, X_AXIS), (0.0, Y_AXIS), (20.0, XY_AXIS)],
'NoBodies': [],
'SkewedDCM': [(20.0, X_AXIS), (15.0, Y_AXIS)],
'AsymmetricInertia': [(20.0, X_AXIS), (15.0, Y_AXIS)],
'TriangleInertia': [(20.0, X_AXIS), (15.0, Y_AXIS)],
}
[docs]
@pytest.mark.parametrize("scheduleEffector", [True, False])
@pytest.mark.parametrize("chain, shouldRaise", [
('Valid', False),
('MasslessJoint', False),
('MasslessChain', False),
('MasslessOutermost', True),
('CollinearMassless', True),
('CoplanarMassless', True),
('NoBodies', True),
('SkewedDCM', True),
('AsymmetricInertia', True),
('TriangleInertia', True),
])
def test_translatingBodyConfigurationValidation(chain, shouldRaise, scheduleEffector):
"""
Verify that initialization rejects a chain the equations of motion cannot represent, and that a
massless body used to build a multiple degree of freedom joint is not one of them.
The joint mass matrix sums the masses outboard of each axis. A body may be left massless so that
several single axis bodies compose one multi-axis joint, but the matrix is singular whenever some
nonzero combination of axis rates leaves every body carrying mass at rest. That covers a massless
outermost body and a massless body sharing its axis with the body outboard of it, and it is a
collective condition rather than a pairwise one: massless stages along x and y followed by a
massive stage along x + y have pairwise independent axes yet span only two dimensions, so they
are rejected as well.
Inverting a singular matrix fills the spacecraft state with NaN rather than raising, which is why
this is asserted as an error at initialization instead of as a tolerance on a trajectory. The
axes are fixed in their parents and a translating body does not rotate, so the matrix never
changes during the integration. The singular cases also verify that the error reports this
collective condition rather than a more restrictive axis-independence rule. The rotation matrix
and inertia tensor checks match those the spinning body effectors already apply, including
skipping the inertia check for a massless body, whose inertia tensor is legitimately zero.
An accepted chain is integrated as well, because initializing without error would not show that
a massless body carries the correct dynamics. Every damper is zero, so the rotational energy and
the rotational angular momentum about the vehicle center of mass must both be conserved.
**Test Parameters:**
- chain: [string]
translating body configuration to initialize
- shouldRaise: [bool]
whether initialization must reject the configuration
- scheduleEffector: [bool]
whether the effector is added to the task in addition to the spacecraft
The scheduling parameter matters because the checks must not depend on it. Spacecraft
initialization calls ``registerStates()`` on every attached state effector but never calls
``Reset()``, which runs only for a module added to a task. The module user guide adds the
effector to the spacecraft alone, so validation reached from ``Reset()`` would miss the
documented setup and let a singular chain integrate to NaN.
"""
scObject = spacecraft.Spacecraft()
scObject.ModelTag = "spacecraftBody"
scObject.hub.mHub = 750.0 # [kg]
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.omega_BN_BInit = [[0.1], [-0.2], [0.3]] # [rad/s]
effector = linearTranslationNDOFStateEffector.LinearTranslationNDOFStateEffector()
for mass, fHat_P in VALIDATION_CHAINS[chain]:
body = linearTranslationNDOFStateEffector.TranslatingBody()
body.setMass(mass) # [kg]
if mass == 0.0:
body.setIPntFc_F([[0.0, 0.0, 0.0], [0.0, 0.0, 0.0], [0.0, 0.0, 0.0]]) # [kg*m^2]
if chain == 'SkewedDCM':
body.setDCM_FP([[1.0, 0.1, 0.0], [0.0, 1.0, 0.0], [0.0, 0.0, 1.0]])
if chain == 'AsymmetricInertia':
body.setIPntFc_F([[50.0, 3.0, 0.0], [0.0, 80.0, 0.0], [0.0, 0.0, 60.0]]) # [kg*m^2]
if chain == 'TriangleInertia':
# positive definite, but the principal moments violate the triangle inequality
body.setIPntFc_F([[10.0, 0.0, 0.0], [0.0, 10.0, 0.0], [0.0, 0.0, 90.0]]) # [kg*m^2]
body.setR_FcF_F([[0.5], [0.2], [-0.3]]) # [m]
body.setR_F0P_P([[1.0], [0.5], [0.25]]) # [m]
body.setFHat_P(fHat_P)
body.setRhoInit(0.1) # [m]
body.setRhoDotInit(0.05) # [m/s]
body.setK(10.0) # [N/m]
effector.addTranslatingBody(body)
scObject.addStateEffector(effector)
unitTestSim = SimulationBaseClass.SimBaseClass()
unitTestSim.SetProgressBar(False)
unitTestSim.CreateNewProcess("TestProcess").addTask(
unitTestSim.CreateNewTask("unitTask", macros.sec2nano(0.001)))
if scheduleEffector:
unitTestSim.AddModelToTask("unitTask", effector)
unitTestSim.AddModelToTask("unitTask", scObject)
conservationLog = scObject.logger(["totRotEnergy", "totRotAngMomPntC_N"])
unitTestSim.AddModelToTask("unitTask", conservationLog)
if shouldRaise:
with pytest.raises(BasiliskError) as error:
unitTestSim.InitializeSimulation()
if chain in ('MasslessOutermost', 'CollinearMassless', 'CoplanarMassless'):
assert "nonzero combination of joint rates leaves every mass-bearing body stationary" in str(error.value)
return
unitTestSim.InitializeSimulation()
unitTestSim.ConfigureStopTime(macros.sec2nano(1.0))
unitTestSim.ExecuteSimulation()
accuracy = 1e-10
rotEnergy = np.array(conservationLog.totRotEnergy)
rotAngMom = np.array(conservationLog.totRotAngMomPntC_N)
np.testing.assert_allclose(rotEnergy, rotEnergy[0], rtol=accuracy,
err_msg="Rotational energy is not constant.")
np.testing.assert_allclose(rotAngMom, np.broadcast_to(rotAngMom[0], rotAngMom.shape),
rtol=accuracy,
err_msg="Rotational angular momentum is not constant.")
[docs]
def translatingBodyNoInput(show_plots):
r"""
This test does not use any input messages or lock flags, so the links are free to move.
"""
scObject = spacecraft.Spacecraft()
scObject.ModelTag = "spacecraftBody"
unitTaskName = "unitTask" # arbitrary name (don't change)
unitProcessName = "TestProcess" # arbitrary name (don't change)
# Create a sim module as an empty container
unitTestSim = SimulationBaseClass.SimBaseClass()
# Create test thread
testProcessRate = macros.sec2nano(0.001) # update process rate update time
testProc = unitTestSim.CreateNewProcess(unitProcessName)
testProc.addTask(unitTestSim.CreateNewTask(unitTaskName, testProcessRate))
# Create four translating rigid bodies
translatingBodyEffector = linearTranslationNDOFStateEffector.LinearTranslationNDOFStateEffector()
translatingBodyEffector.ModelTag = "translatingBodyEffector"
# define properties
translatingBody1 = linearTranslationNDOFStateEffector.TranslatingBody()
translatingBody1.setMass(np.random.uniform(5.0, 50.0))
translatingBody1.setIPntFc_F(randomValidInertia())
translatingBody1.setDCM_FP([[0.0, -1.0, 0.0], [0.0, 0.0, -1.0], [1.0, 0.0, 0.0]])
translatingBody1.setR_FcF_F([[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)]])
translatingBody1.setR_F0P_P([[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)]])
translatingBody1.setFHat_P([[3.0 / 5.0], [4.0 / 5.0], [0.0]])
translatingBody1.setRhoInit(np.random.uniform(-5.0, 10.0))
translatingBody1.setRhoDotInit(0.05)
translatingBody1.setK(np.random.random())
translatingBodyEffector.addTranslatingBody(translatingBody1)
translatingBody2 = linearTranslationNDOFStateEffector.TranslatingBody()
translatingBody2.setMass(np.random.uniform(5.0, 50.0))
translatingBody2.setIPntFc_F(randomValidInertia())
translatingBody2.setDCM_FP([[1.0, 0.0, 0.0], [0.0, 1.0, 0.0], [0.0, 0.0, 1.0]])
translatingBody2.setR_FcF_F([[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)]])
translatingBody2.setR_F0P_P([[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)]])
translatingBody2.setFHat_P([[3.0 / 5.0], [4.0 / 5.0], [0.0]])
translatingBody2.setRhoInit(np.random.uniform(-5.0, 5.0))
translatingBody2.setRhoDotInit(0.05)
translatingBody2.setK(np.random.random())
translatingBodyEffector.addTranslatingBody(translatingBody2)
translatingBody3 = linearTranslationNDOFStateEffector.TranslatingBody()
translatingBody3.setMass(np.random.uniform(5.0, 50.0))
translatingBody3.setIPntFc_F(randomValidInertia())
translatingBody3.setDCM_FP([[1.0, 0.0, 0.0], [0.0, 1.0, 0.0], [0.0, 0.0, 1.0]])
translatingBody3.setR_FcF_F([[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)]])
translatingBody3.setR_F0P_P([[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)]])
translatingBody3.setFHat_P([[3.0 / 5.0], [4.0 / 5.0], [0.0]])
translatingBody3.setRhoInit(np.random.uniform(-5.0, 5.0))
translatingBody3.setRhoDotInit(0.05)
translatingBody3.setK(np.random.random())
translatingBodyEffector.addTranslatingBody(translatingBody3)
translatingBody4 = linearTranslationNDOFStateEffector.TranslatingBody()
translatingBody4.setMass(np.random.uniform(5.0, 50.0))
translatingBody4.setIPntFc_F(randomValidInertia())
translatingBody4.setDCM_FP([[1.0, 0.0, 0.0], [0.0, 1.0, 0.0], [0.0, 0.0, 1.0]])
translatingBody4.setR_FcF_F([[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)]])
translatingBody4.setR_F0P_P([[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)]])
translatingBody4.setFHat_P([[0.0], [0.0], [1.0]])
translatingBody4.setRhoInit(np.random.uniform(-5.0, 5.0))
translatingBody4.setRhoDotInit(0.05)
translatingBody4.setK(np.random.random())
translatingBodyEffector.addTranslatingBody(translatingBody4)
# Add body to spacecraft
scObject.addStateEffector(translatingBodyEffector)
# Define mass properties of the rigid hub of the spacecraft
scObject.hub.mHub = 750.0
scObject.hub.r_BcB_B = [[0.0], [0.0], [1.0]]
scObject.hub.IHubPntBc_B = [[900.0, 0.0, 0.0], [0.0, 800.0, 0.0], [0.0, 0.0, 600.0]]
# Set the initial values for the states
scObject.hub.r_CN_NInit = [[-4020338.690396649], [7490566.741852513], [5248299.211589362]]
scObject.hub.v_CN_NInit = [[-5199.77710904224], [-3436.681645356935], [1041.576797498721]]
scObject.hub.sigma_BNInit = [[0.0], [0.0], [0.0]]
scObject.hub.omega_BN_BInit = [[0.1], [-0.1], [0.1]]
# Add test module to runtime call list
unitTestSim.AddModelToTask(unitTaskName, translatingBodyEffector)
unitTestSim.AddModelToTask(unitTaskName, scObject)
# Add Earth gravity to the simulation
earthGravBody = gravityEffector.GravBodyData()
earthGravBody.planetName = "earth_planet_data"
earthGravBody.mu = 0.3986004415E+15 # meters!
earthGravBody.isCentralBody = True
scObject.gravField.gravBodies = spacecraft.GravBodyVector([earthGravBody])
# Log the spacecraft state message
datLog = scObject.scStateOutMsg.recorder()
unitTestSim.AddModelToTask(unitTaskName, datLog)
# Initialize the simulation
unitTestSim.InitializeSimulation()
# Add energy and momentum variables to log
scObjectLog = scObject.logger(["totOrbAngMomPntN_N", "totRotAngMomPntC_N", "totOrbEnergy", "totRotEnergy"])
unitTestSim.AddModelToTask(unitTaskName, scObjectLog)
# Add states to log
rho1Data = translatingBodyEffector.translatingBodyOutMsgs[0].recorder()
unitTestSim.AddModelToTask(unitTaskName, rho1Data)
rho2Data = translatingBodyEffector.translatingBodyOutMsgs[1].recorder()
unitTestSim.AddModelToTask(unitTaskName, rho2Data)
rho3Data = translatingBodyEffector.translatingBodyOutMsgs[2].recorder()
unitTestSim.AddModelToTask(unitTaskName, rho3Data)
rho4Data = translatingBodyEffector.translatingBodyOutMsgs[3].recorder()
unitTestSim.AddModelToTask(unitTaskName, rho4Data)
# Setup and run the simulation
stopTime = 5000 * testProcessRate
unitTestSim.ConfigureStopTime(stopTime)
unitTestSim.ExecuteSimulation()
# Extract the logged variables
orbAngMom_N = scObjectLog.totOrbAngMomPntN_N
rotAngMom_N = scObjectLog.totRotAngMomPntC_N
rotEnergy = scObjectLog.totRotEnergy
orbEnergy = scObjectLog.totOrbEnergy
rho1 = rho1Data.rho
rho1Dot = rho1Data.rhoDot
rho2 = rho2Data.rho
rho2Dot = rho2Data.rhoDot
rho3 = rho3Data.rho
rho3Dot = rho3Data.rhoDot
rho4 = rho4Data.rho
rho4Dot = rho4Data.rhoDot
# Set up the conservation quantities
timeSec = scObjectLog.times() * 1e-9
initialOrbAngMom_N = [orbAngMom_N[0, 0], orbAngMom_N[0, 1], orbAngMom_N[0, 2]]
finalOrbAngMom = orbAngMom_N[-1]
initialRotAngMom_N = [rotAngMom_N[0, 0], rotAngMom_N[0, 1], rotAngMom_N[0, 2]]
finalRotAngMom = rotAngMom_N[-1]
initialOrbEnergy = orbEnergy[0]
finalOrbEnergy = orbEnergy[-1]
initialRotEnergy = rotEnergy[0]
finalRotEnergy = rotEnergy[-1]
# Plotting
plt.close("all")
plt.figure()
plt.clf()
plt.plot(timeSec, (orbAngMom_N[:, 0] - initialOrbAngMom_N[0]) / initialOrbAngMom_N[0],
timeSec, (orbAngMom_N[:, 1] - initialOrbAngMom_N[1]) / initialOrbAngMom_N[1],
timeSec, (orbAngMom_N[:, 2] - initialOrbAngMom_N[2]) / initialOrbAngMom_N[2])
plt.xlabel('time (s)')
plt.ylabel('Relative Difference')
plt.title('Orbital Angular Momentum')
plt.figure()
plt.clf()
plt.plot(timeSec, (orbEnergy - initialOrbEnergy) / initialOrbEnergy)
plt.xlabel('time (s)')
plt.ylabel('Relative Difference')
plt.title('Orbital Energy')
plt.figure()
plt.clf()
plt.plot(timeSec, (rotAngMom_N[:, 0] - initialRotAngMom_N[0]) / initialRotAngMom_N[0],
timeSec, (rotAngMom_N[:, 1] - initialRotAngMom_N[1]) / initialRotAngMom_N[1],
timeSec, (rotAngMom_N[:, 2] - initialRotAngMom_N[2]) / initialRotAngMom_N[2])
plt.xlabel('time (s)')
plt.ylabel('Relative Difference')
plt.title('Rotational Angular Momentum')
plt.figure()
plt.clf()
plt.plot(timeSec, (rotEnergy - initialRotEnergy) / initialRotEnergy)
plt.xlabel('time (s)')
plt.ylabel('Relative Difference')
plt.title('Rotational Energy')
plt.figure()
plt.clf()
plt.plot(rho1Data.times() * 1e-9, rho1, label=r'$\rho_1$')
plt.plot(rho2Data.times() * 1e-9, rho2, label=r'$\rho_2$')
plt.plot(rho3Data.times() * 1e-9, rho3, label=r'$\rho_3$')
plt.plot(rho4Data.times() * 1e-9, rho4, label=r'$\rho_4$')
plt.legend(loc='best')
plt.xlabel('time (s)')
plt.ylabel('Displacement')
plt.figure()
plt.clf()
plt.plot(rho1Data.times() * 1e-9, rho1Dot, label=r'$\dot{\rho}_1$')
plt.plot(rho2Data.times() * 1e-9, rho2Dot, label=r'$\dot{\rho}_2$')
plt.plot(rho3Data.times() * 1e-9, rho3Dot, label=r'$\dot{\rho}_3$')
plt.plot(rho4Data.times() * 1e-9, rho4Dot, label=r'$\dot{\rho}_4$')
plt.legend(loc='best')
plt.xlabel('time (s)')
plt.ylabel('Displacement Rate')
if show_plots:
plt.show()
plt.close("all")
# Testing setup
accuracy = 1e-13
np.testing.assert_allclose(finalOrbEnergy, initialOrbEnergy, rtol=accuracy, err_msg="Orbital energy is not constant.")
np.testing.assert_allclose(finalRotEnergy, initialRotEnergy, rtol=accuracy,
err_msg="Rotational energy is not constant.")
for i in range(3):
np.testing.assert_allclose(finalOrbAngMom, initialOrbAngMom_N, rtol=accuracy,
err_msg="Orbital angular momentum is not constant.")
np.testing.assert_allclose(finalRotAngMom, initialRotAngMom_N, rtol=accuracy,
err_msg="Rotational angular momentum is not constant.")
[docs]
def translatingBodyLockAxis(show_plots):
r"""
This test locks the axis, so the displacement is kept constant throughout the simulation.
"""
scObject = spacecraft.Spacecraft()
scObject.ModelTag = "spacecraftBody"
unitTaskName = "unitTask" # arbitrary name (don't change)
unitProcessName = "TestProcess" # arbitrary name (don't change)
# Create a sim module as an empty container
unitTestSim = SimulationBaseClass.SimBaseClass()
# Create test thread
testProcessRate = macros.sec2nano(0.001) # update process rate update time
testProc = unitTestSim.CreateNewProcess(unitProcessName)
testProc.addTask(unitTestSim.CreateNewTask(unitTaskName, testProcessRate))
# Create four translating rigid bodies
translatingBodyEffector = linearTranslationNDOFStateEffector.LinearTranslationNDOFStateEffector()
translatingBodyEffector.ModelTag = "translatingBodyEffector"
# define properties
translatingBody1 = linearTranslationNDOFStateEffector.TranslatingBody()
translatingBody1.setMass(np.random.uniform(5.0, 50.0))
translatingBody1.setIPntFc_F(randomValidInertia())
translatingBody1.setDCM_FP([[0.0, -1.0, 0.0], [0.0, 0.0, -1.0], [1.0, 0.0, 0.0]])
translatingBody1.setR_FcF_F([[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)]])
translatingBody1.setR_F0P_P([[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)]])
translatingBody1.setFHat_P([[3.0 / 5.0], [4.0 / 5.0], [0.0]])
translatingBody1.setRhoInit(np.random.uniform(-5.0, 10.0))
translatingBody1.setRhoDotInit(0.05)
translatingBody1.setK(np.random.random())
translatingBodyEffector.addTranslatingBody(translatingBody1)
translatingBody2 = linearTranslationNDOFStateEffector.TranslatingBody()
translatingBody2.setMass(np.random.uniform(5.0, 50.0))
translatingBody2.setIPntFc_F(randomValidInertia())
translatingBody2.setDCM_FP([[1.0, 0.0, 0.0], [0.0, 1.0, 0.0], [0.0, 0.0, 1.0]])
translatingBody2.setR_FcF_F([[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)]])
translatingBody2.setR_F0P_P([[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)]])
translatingBody2.setFHat_P([[3.0 / 5.0], [4.0 / 5.0], [0.0]])
translatingBody2.setRhoInit(np.random.uniform(-5.0, 5.0))
translatingBody2.setRhoDotInit(0.05)
translatingBody2.setK(np.random.random())
translatingBodyEffector.addTranslatingBody(translatingBody2)
translatingBody3 = linearTranslationNDOFStateEffector.TranslatingBody()
translatingBody3.setMass(np.random.uniform(5.0, 50.0))
translatingBody3.setIPntFc_F(randomValidInertia())
translatingBody3.setDCM_FP([[1.0, 0.0, 0.0], [0.0, 1.0, 0.0], [0.0, 0.0, 1.0]])
translatingBody3.setR_FcF_F([[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)]])
translatingBody3.setR_F0P_P([[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)]])
translatingBody3.setFHat_P([[3.0 / 5.0], [4.0 / 5.0], [0.0]])
translatingBody3.setRhoInit(np.random.uniform(-5.0, 5.0))
translatingBody3.setRhoDotInit(0.05)
translatingBody3.setK(np.random.random())
translatingBodyEffector.addTranslatingBody(translatingBody3)
translatingBody4 = linearTranslationNDOFStateEffector.TranslatingBody()
translatingBody4.setMass(np.random.uniform(5.0, 50.0))
translatingBody4.setIPntFc_F(randomValidInertia())
translatingBody4.setDCM_FP([[1.0, 0.0, 0.0], [0.0, 1.0, 0.0], [0.0, 0.0, 1.0]])
translatingBody4.setR_FcF_F([[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)]])
translatingBody4.setR_F0P_P([[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)]])
translatingBody4.setFHat_P([[0.0], [0.0], [1.0]])
translatingBody4.setRhoInit(np.random.uniform(-5.0, 5.0))
translatingBody4.setRhoDotInit(0.05)
translatingBody4.setK(np.random.random())
translatingBodyEffector.addTranslatingBody(translatingBody4)
# Add body to spacecraft
scObject.addStateEffector(translatingBodyEffector)
# Define mass properties of the rigid hub of the spacecraft
scObject.hub.mHub = 750.0
scObject.hub.r_BcB_B = [[0.0], [0.0], [1.0]]
scObject.hub.IHubPntBc_B = [[900.0, 0.0, 0.0], [0.0, 800.0, 0.0], [0.0, 0.0, 600.0]]
# Set the initial values for the states
scObject.hub.r_CN_NInit = [[-4020338.690396649], [7490566.741852513], [5248299.211589362]]
scObject.hub.v_CN_NInit = [[-5199.77710904224], [-3436.681645356935], [1041.576797498721]]
scObject.hub.sigma_BNInit = [[0.0], [0.0], [0.0]]
scObject.hub.omega_BN_BInit = [[0.1], [-0.1], [0.1]]
# Add test module to runtime call list
unitTestSim.AddModelToTask(unitTaskName, translatingBodyEffector)
unitTestSim.AddModelToTask(unitTaskName, scObject)
# Add Earth gravity to the simulation
earthGravBody = gravityEffector.GravBodyData()
earthGravBody.planetName = "earth_planet_data"
earthGravBody.mu = 0.3986004415E+15 # meters!
earthGravBody.isCentralBody = True
scObject.gravField.gravBodies = spacecraft.GravBodyVector([earthGravBody])
# create lock message
lockArray = messaging.ArrayEffectorLockMsgPayload()
lockArray.effectorLockFlag = [1, 0, 0, 1]
lockMsg = messaging.ArrayEffectorLockMsg().write(lockArray)
translatingBodyEffector.motorLockInMsg.subscribeTo(lockMsg)
# Log the spacecraft state message
datLog = scObject.scStateOutMsg.recorder()
unitTestSim.AddModelToTask(unitTaskName, datLog)
# Initialize the simulation
unitTestSim.InitializeSimulation()
# Add energy and momentum variables to log
scObjectLog = scObject.logger(["totOrbAngMomPntN_N", "totRotAngMomPntC_N", "totOrbEnergy", "totRotEnergy"])
unitTestSim.AddModelToTask(unitTaskName, scObjectLog)
# Add states to log
rho1Data = translatingBodyEffector.translatingBodyOutMsgs[0].recorder()
unitTestSim.AddModelToTask(unitTaskName, rho1Data)
rho2Data = translatingBodyEffector.translatingBodyOutMsgs[1].recorder()
unitTestSim.AddModelToTask(unitTaskName, rho2Data)
rho3Data = translatingBodyEffector.translatingBodyOutMsgs[2].recorder()
unitTestSim.AddModelToTask(unitTaskName, rho3Data)
rho4Data = translatingBodyEffector.translatingBodyOutMsgs[3].recorder()
unitTestSim.AddModelToTask(unitTaskName, rho4Data)
# Setup and run the simulation
stopTime = 5000 * testProcessRate
unitTestSim.ConfigureStopTime(stopTime)
unitTestSim.ExecuteSimulation()
# Extract the logged variables
orbAngMom_N = scObjectLog.totOrbAngMomPntN_N
rotAngMom_N = scObjectLog.totRotAngMomPntC_N
rotEnergy = scObjectLog.totRotEnergy
orbEnergy = scObjectLog.totOrbEnergy
rho1 = rho1Data.rho
rho1Dot = rho1Data.rhoDot
rho2 = rho2Data.rho
rho2Dot = rho2Data.rhoDot
rho3 = rho3Data.rho
rho3Dot = rho3Data.rhoDot
rho4 = rho4Data.rho
rho4Dot = rho4Data.rhoDot
# Set up the conservation quantities
timeSec = scObjectLog.times() * 1e-9
initialOrbAngMom_N = [orbAngMom_N[0, 0], orbAngMom_N[0, 1], orbAngMom_N[0, 2]]
finalOrbAngMom = orbAngMom_N[-1]
initialRotAngMom_N = [rotAngMom_N[0, 0], rotAngMom_N[0, 1], rotAngMom_N[0, 2]]
finalRotAngMom = rotAngMom_N[-1]
initialOrbEnergy = orbEnergy[0]
finalOrbEnergy = orbEnergy[-1]
initialRotEnergy = rotEnergy[0]
finalRotEnergy = rotEnergy[-1]
# Plotting
plt.close("all")
plt.figure()
plt.clf()
plt.plot(timeSec, (orbAngMom_N[:, 0] - initialOrbAngMom_N[0]) / initialOrbAngMom_N[0],
timeSec, (orbAngMom_N[:, 1] - initialOrbAngMom_N[1]) / initialOrbAngMom_N[1],
timeSec, (orbAngMom_N[:, 2] - initialOrbAngMom_N[2]) / initialOrbAngMom_N[2])
plt.xlabel('time (s)')
plt.ylabel('Relative Difference')
plt.title('Orbital Angular Momentum')
plt.figure()
plt.clf()
plt.plot(timeSec, (orbEnergy - initialOrbEnergy) / initialOrbEnergy)
plt.xlabel('time (s)')
plt.ylabel('Relative Difference')
plt.title('Orbital Energy')
plt.figure()
plt.clf()
plt.plot(timeSec, (rotAngMom_N[:, 0] - initialRotAngMom_N[0]) / initialRotAngMom_N[0],
timeSec, (rotAngMom_N[:, 1] - initialRotAngMom_N[1]) / initialRotAngMom_N[1],
timeSec, (rotAngMom_N[:, 2] - initialRotAngMom_N[2]) / initialRotAngMom_N[2])
plt.xlabel('time (s)')
plt.ylabel('Relative Difference')
plt.title('Rotational Angular Momentum')
plt.figure()
plt.clf()
plt.plot(timeSec, (rotEnergy - initialRotEnergy) / initialRotEnergy)
plt.xlabel('time (s)')
plt.ylabel('Relative Difference')
plt.title('Rotational Energy')
plt.figure()
plt.clf()
plt.plot(rho1Data.times() * 1e-9, rho1, label=r'$\rho_1$')
plt.plot(rho2Data.times() * 1e-9, rho2, label=r'$\rho_2$')
plt.plot(rho3Data.times() * 1e-9, rho3, label=r'$\rho_3$')
plt.plot(rho4Data.times() * 1e-9, rho4, label=r'$\rho_4$')
plt.legend(loc='best')
plt.xlabel('time (s)')
plt.ylabel('Displacement')
plt.figure()
plt.clf()
plt.plot(rho1Data.times() * 1e-9, rho1Dot, label=r'$\dot{\rho}_1$')
plt.plot(rho2Data.times() * 1e-9, rho2Dot, label=r'$\dot{\rho}_2$')
plt.plot(rho3Data.times() * 1e-9, rho3Dot, label=r'$\dot{\rho}_3$')
plt.plot(rho4Data.times() * 1e-9, rho4Dot, label=r'$\dot{\rho}_4$')
plt.legend(loc='best')
plt.xlabel('time (s)')
plt.ylabel('Displacement Rate')
if show_plots:
plt.show()
plt.close("all")
# Testing setup
accuracy = 1e-13
np.testing.assert_allclose(finalOrbEnergy, initialOrbEnergy, rtol=accuracy,
err_msg="Orbital energy is not constant.")
np.testing.assert_allclose(finalRotEnergy, initialRotEnergy, rtol=accuracy,
err_msg="Rotational energy is not constant.")
for i in range(3):
np.testing.assert_allclose(finalOrbAngMom, initialOrbAngMom_N, rtol=accuracy,
err_msg="Orbital angular momentum is not constant.")
np.testing.assert_allclose(finalRotAngMom, initialRotAngMom_N, rtol=accuracy,
err_msg="Rotational angular momentum is not constant.")
[docs]
def translatingBodyCommandedForce(show_plots):
r"""
This test includes a commanded force to the link, so energy is not conserved.
"""
scObject = spacecraft.Spacecraft()
scObject.ModelTag = "spacecraftBody"
unitTaskName = "unitTask" # arbitrary name (don't change)
unitProcessName = "TestProcess" # arbitrary name (don't change)
# Create a sim module as an empty container
unitTestSim = SimulationBaseClass.SimBaseClass()
# Create test thread
testProcessRate = macros.sec2nano(0.001) # update process rate update time
testProc = unitTestSim.CreateNewProcess(unitProcessName)
testProc.addTask(unitTestSim.CreateNewTask(unitTaskName, testProcessRate))
# Create four translating rigid bodies
translatingBodyEffector = linearTranslationNDOFStateEffector.LinearTranslationNDOFStateEffector()
translatingBodyEffector.ModelTag = "translatingBodyEffector"
# define properties
translatingBody1 = linearTranslationNDOFStateEffector.TranslatingBody()
translatingBody1.setMass(np.random.uniform(5.0, 50.0))
translatingBody1.setIPntFc_F(randomValidInertia())
translatingBody1.setDCM_FP([[0.0, -1.0, 0.0], [0.0, 0.0, -1.0], [1.0, 0.0, 0.0]])
translatingBody1.setR_FcF_F([[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)]])
translatingBody1.setR_F0P_P([[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)]])
translatingBody1.setFHat_P([[3.0 / 5.0], [4.0 / 5.0], [0.0]])
translatingBody1.setRhoInit(np.random.uniform(-5.0, 10.0))
translatingBody1.setRhoDotInit(0.05)
translatingBody1.setK(np.random.random())
translatingBodyEffector.addTranslatingBody(translatingBody1)
translatingBody2 = linearTranslationNDOFStateEffector.TranslatingBody()
translatingBody2.setMass(np.random.uniform(5.0, 50.0))
translatingBody2.setIPntFc_F(randomValidInertia())
translatingBody2.setDCM_FP([[1.0, 0.0, 0.0], [0.0, 1.0, 0.0], [0.0, 0.0, 1.0]])
translatingBody2.setR_FcF_F([[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)]])
translatingBody2.setR_F0P_P([[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)]])
translatingBody2.setFHat_P([[3.0 / 5.0], [4.0 / 5.0], [0.0]])
translatingBody2.setRhoInit(np.random.uniform(-5.0, 5.0))
translatingBody2.setRhoDotInit(0.05)
translatingBody2.setK(np.random.random())
translatingBodyEffector.addTranslatingBody(translatingBody2)
translatingBody3 = linearTranslationNDOFStateEffector.TranslatingBody()
translatingBody3.setMass(np.random.uniform(5.0, 50.0))
translatingBody3.setIPntFc_F(randomValidInertia())
translatingBody3.setDCM_FP([[1.0, 0.0, 0.0], [0.0, 1.0, 0.0], [0.0, 0.0, 1.0]])
translatingBody3.setR_FcF_F([[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)]])
translatingBody3.setR_F0P_P([[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)]])
translatingBody3.setFHat_P([[3.0 / 5.0], [4.0 / 5.0], [0.0]])
translatingBody3.setRhoInit(np.random.uniform(-5.0, 5.0))
translatingBody3.setRhoDotInit(0.05)
translatingBody3.setK(np.random.random())
translatingBodyEffector.addTranslatingBody(translatingBody3)
translatingBody4 = linearTranslationNDOFStateEffector.TranslatingBody()
translatingBody4.setMass(np.random.uniform(5.0, 50.0))
translatingBody4.setIPntFc_F(randomValidInertia())
translatingBody4.setDCM_FP([[1.0, 0.0, 0.0], [0.0, 1.0, 0.0], [0.0, 0.0, 1.0]])
translatingBody4.setR_FcF_F([[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)]])
translatingBody4.setR_F0P_P([[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)],
[np.random.uniform(-1.0, 1.0)]])
translatingBody4.setFHat_P([[0.0], [0.0], [1.0]])
translatingBody4.setRhoInit(np.random.uniform(-5.0, 5.0))
translatingBody4.setRhoDotInit(0.05)
translatingBody4.setK(np.random.random())
translatingBodyEffector.addTranslatingBody(translatingBody4)
# Add body to spacecraft
scObject.addStateEffector(translatingBodyEffector)
# Define mass properties of the rigid hub of the spacecraft
scObject.hub.mHub = 750.0
scObject.hub.r_BcB_B = [[0.0], [0.0], [1.0]]
scObject.hub.IHubPntBc_B = [[900.0, 0.0, 0.0], [0.0, 800.0, 0.0], [0.0, 0.0, 600.0]]
# Set the initial values for the states
scObject.hub.r_CN_NInit = [[-4020338.690396649], [7490566.741852513], [5248299.211589362]]
scObject.hub.v_CN_NInit = [[-5199.77710904224], [-3436.681645356935], [1041.576797498721]]
scObject.hub.sigma_BNInit = [[0.0], [0.0], [0.0]]
scObject.hub.omega_BN_BInit = [[0.1], [-0.1], [0.1]]
# Add test module to runtime call list
unitTestSim.AddModelToTask(unitTaskName, translatingBodyEffector)
unitTestSim.AddModelToTask(unitTaskName, scObject)
# Add Earth gravity to the simulation
earthGravBody = gravityEffector.GravBodyData()
earthGravBody.planetName = "earth_planet_data"
earthGravBody.mu = 0.3986004415E+15 # meters!
earthGravBody.isCentralBody = True
scObject.gravField.gravBodies = spacecraft.GravBodyVector([earthGravBody])
# Create the force message
cmdArray = messaging.ArrayMotorForceMsgPayload()
cmdArray.motorForce = [0.1, -0.2, 0.3, -0.15] # [Nm]
cmdMsg = messaging.ArrayMotorForceMsg().write(cmdArray)
translatingBodyEffector.motorForceInMsg.subscribeTo(cmdMsg)
# Log the spacecraft state message
datLog = scObject.scStateOutMsg.recorder()
unitTestSim.AddModelToTask(unitTaskName, datLog)
# Initialize the simulation
unitTestSim.InitializeSimulation()
# Add energy and momentum variables to log
scObjectLog = scObject.logger(["totOrbAngMomPntN_N", "totRotAngMomPntC_N", "totOrbEnergy", "totRotEnergy"])
unitTestSim.AddModelToTask(unitTaskName, scObjectLog)
# Add states to log
rho1Data = translatingBodyEffector.translatingBodyOutMsgs[0].recorder()
unitTestSim.AddModelToTask(unitTaskName, rho1Data)
rho2Data = translatingBodyEffector.translatingBodyOutMsgs[1].recorder()
unitTestSim.AddModelToTask(unitTaskName, rho2Data)
rho3Data = translatingBodyEffector.translatingBodyOutMsgs[2].recorder()
unitTestSim.AddModelToTask(unitTaskName, rho3Data)
rho4Data = translatingBodyEffector.translatingBodyOutMsgs[3].recorder()
unitTestSim.AddModelToTask(unitTaskName, rho4Data)
# Setup and run the simulation
stopTime = 5000 * testProcessRate
unitTestSim.ConfigureStopTime(stopTime)
unitTestSim.ExecuteSimulation()
# Extract the logged variables
orbAngMom_N = scObjectLog.totOrbAngMomPntN_N
rotAngMom_N = scObjectLog.totRotAngMomPntC_N
rotEnergy = scObjectLog.totRotEnergy
orbEnergy = scObjectLog.totOrbEnergy
rho1 = rho1Data.rho
rho1Dot = rho1Data.rhoDot
rho2 = rho2Data.rho
rho2Dot = rho2Data.rhoDot
rho3 = rho3Data.rho
rho3Dot = rho3Data.rhoDot
rho4 = rho4Data.rho
rho4Dot = rho4Data.rhoDot
# Set up the conservation quantities
timeSec = scObjectLog.times() * 1e-9
initialOrbAngMom_N = [orbAngMom_N[0, 0], orbAngMom_N[0, 1], orbAngMom_N[0, 2]]
finalOrbAngMom = orbAngMom_N[-1]
initialRotAngMom_N = [rotAngMom_N[0, 0], rotAngMom_N[0, 1], rotAngMom_N[0, 2]]
finalRotAngMom = rotAngMom_N[-1]
initialOrbEnergy = orbEnergy[0]
finalOrbEnergy = orbEnergy[-1]
initialRotEnergy = rotEnergy[0]
# Plotting
plt.close("all")
plt.figure()
plt.clf()
plt.plot(timeSec, (orbAngMom_N[:, 0] - initialOrbAngMom_N[0]) / initialOrbAngMom_N[0],
timeSec, (orbAngMom_N[:, 1] - initialOrbAngMom_N[1]) / initialOrbAngMom_N[1],
timeSec, (orbAngMom_N[:, 2] - initialOrbAngMom_N[2]) / initialOrbAngMom_N[2])
plt.xlabel('time (s)')
plt.ylabel('Relative Difference')
plt.title('Orbital Angular Momentum')
plt.figure()
plt.clf()
plt.plot(timeSec, (orbEnergy - initialOrbEnergy) / initialOrbEnergy)
plt.xlabel('time (s)')
plt.ylabel('Relative Difference')
plt.title('Orbital Energy')
plt.figure()
plt.clf()
plt.plot(timeSec, (rotAngMom_N[:, 0] - initialRotAngMom_N[0]) / initialRotAngMom_N[0],
timeSec, (rotAngMom_N[:, 1] - initialRotAngMom_N[1]) / initialRotAngMom_N[1],
timeSec, (rotAngMom_N[:, 2] - initialRotAngMom_N[2]) / initialRotAngMom_N[2])
plt.xlabel('time (s)')
plt.ylabel('Relative Difference')
plt.title('Rotational Angular Momentum')
plt.figure()
plt.clf()
plt.plot(rho1Data.times() * 1e-9, rho1, label=r'$\rho_1$')
plt.plot(rho2Data.times() * 1e-9, rho2, label=r'$\rho_2$')
plt.plot(rho3Data.times() * 1e-9, rho3, label=r'$\rho_3$')
plt.plot(rho4Data.times() * 1e-9, rho4, label=r'$\rho_4$')
plt.legend(loc='best')
plt.xlabel('time (s)')
plt.ylabel('Displacement')
plt.figure()
plt.clf()
plt.plot(rho1Data.times() * 1e-9, rho1Dot, label=r'$\dot{\rho}_1$')
plt.plot(rho2Data.times() * 1e-9, rho2Dot, label=r'$\dot{\rho}_2$')
plt.plot(rho3Data.times() * 1e-9, rho3Dot, label=r'$\dot{\rho}_3$')
plt.plot(rho4Data.times() * 1e-9, rho4Dot, label=r'$\dot{\rho}_4$')
plt.legend(loc='best')
plt.xlabel('time (s)')
plt.ylabel('Displacement Rate')
if show_plots:
plt.show()
plt.close("all")
# Testing setup
accuracy = 1e-13
np.testing.assert_allclose(finalOrbEnergy, initialOrbEnergy, rtol=accuracy,
err_msg="Orbital energy is not constant.")
for i in range(3):
np.testing.assert_allclose(finalOrbAngMom, initialOrbAngMom_N, rtol=accuracy,
err_msg="Orbital angular momentum is not constant.")
np.testing.assert_allclose(finalRotAngMom, initialRotAngMom_N, rtol=accuracy,
err_msg="Rotational angular momentum is not constant.")
if __name__ == "__main__":
translatingBodyNoInput(True)
# translatingBodyLockAxis(True)
# translatingBodyCommandedForce(True)