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# ISC License
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# Copyright (c) 2021, Autonomous Vehicle Systems Lab, University of Colorado Boulder
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import numpy as np
from Basilisk.architecture import messaging
from Basilisk.fswAlgorithms import smallBodyNavEKF
from Basilisk.utilities import SimulationBaseClass
from Basilisk.utilities import macros, orbitalMotion
from Basilisk.utilities import unitTestSupport
from matplotlib import pyplot as plt
[docs]def test_smallBodyNavEKF(show_plots):
r"""
**Validation Test Description**
This unit test checks that the filter converges to a constant state estimate under the presence of static measurements.
No thrusters are used, but a message for each is created and connected to avoid warnings.
**Test Parameters**
Args:
:param show_plots: flag if plots should be shown.
"""
[testResults, testMessage] = smallBodyNavEKFTestFunction(show_plots)
assert testResults < 1, testMessage
[docs]def smallBodyNavEKFTestFunction(show_plots):
"""Test method"""
testFailCount = 0
testMessages = []
unitTaskName = "unitTask"
unitProcessName = "TestProcess"
unitTestSim = SimulationBaseClass.SimBaseClass()
testProcessRate = macros.sec2nano(0.5)
testProc = unitTestSim.CreateNewProcess(unitProcessName)
testProc.addTask(unitTestSim.CreateNewTask(unitTaskName, testProcessRate))
# setup module to be tested
module = smallBodyNavEKF.SmallBodyNavEKF()
module.ModelTag = "smallBodyNavEKFTag"
unitTestSim.AddModelToTask(unitTaskName, module)
# Set the filter parameters (sc area, mass, gravitational constants, etc.)
module.A_sc = 1. # Surface area of the spacecraft, m^2
module.M_sc = 100. # Mass of the spacecraft, kg
module.mu_ast = 5.2 # Gravitational constant of the asteroid
module.Q = (0.1*np.identity(12)).tolist() # Process Noise
module.R = (0.1*np.identity(12)).tolist() # Measurement Noise
bennu_radius = 1.355887692*orbitalMotion.AU*1000.0 # meters
bennu_velocity = np.sqrt(orbitalMotion.MU_SUN*(1000.**3)/bennu_radius) # m/s, assumes circular orbit
x_0 = [2010., 1510., 1010., 0., 2., 0., 0.14, 0., 0., 0., 0., 0.]
module.x_hat_k = x_0
module.P_k = (0.1*np.identity(12)).tolist()
# Configure blank module input messages
navTransInMsgData = messaging.NavTransMsgPayload()
navTransInMsgData.r_BN_N = [bennu_radius + 1000., 1000., 1000.]
navTransInMsgData.v_BN_N = [0., bennu_velocity + 1., 0.]
navTransInMsg = messaging.NavTransMsg().write(navTransInMsgData)
navAttInMsgData = messaging.NavAttMsgPayload()
navAttInMsgData.sigma_BN = [0.1, 0.0, 0.0]
navAttInMsgData.omega_BN_B = [0.0, 0.0, 0.0]
navAttInMsg = messaging.NavAttMsg().write(navAttInMsgData)
asteroidEphemerisInMsgData = messaging.EphemerisMsgPayload()
asteroidEphemerisInMsgData.r_BdyZero_N = [bennu_radius, 0., 0.]
asteroidEphemerisInMsgData.v_BdyZero_N = [0., bennu_velocity, 0.]
asteroidEphemerisInMsgData.sigma_BN = [0.1, 0.0, 0.0]
asteroidEphemerisInMsgData.omega_BN_B = [0.0, 0.0, 0.0]
asteroidEphemerisInMsg = messaging.EphemerisMsg().write(asteroidEphemerisInMsgData)
sunEphemerisInMsgData = messaging.EphemerisMsgPayload()
sunEphemerisInMsg = messaging.EphemerisMsg().write(sunEphemerisInMsgData)
THROutputInMsgData = messaging.THROutputMsgPayload()
THROutputInMsg = messaging.THROutputMsg().write(THROutputInMsgData)
cmdForceInMsgData = messaging.CmdForceBodyMsgPayload()
cmdForceInMsg = messaging.CmdForceBodyMsg().write(cmdForceInMsgData)
# subscribe input messages to module
module.navTransInMsg.subscribeTo(navTransInMsg)
module.navAttInMsg.subscribeTo(navAttInMsg)
module.asteroidEphemerisInMsg.subscribeTo(asteroidEphemerisInMsg)
module.sunEphemerisInMsg.subscribeTo(sunEphemerisInMsg)
module.addThrusterToFilter(THROutputInMsg)
module.cmdForceBodyInMsg.subscribeTo(cmdForceInMsg)
# setup output message recorder objects
navTransOutMsgRec = module.navTransOutMsg.recorder()
unitTestSim.AddModelToTask(unitTaskName, navTransOutMsgRec)
smallBodyNavOutMsgRec = module.smallBodyNavOutMsg.recorder()
unitTestSim.AddModelToTask(unitTaskName, smallBodyNavOutMsgRec)
smallBodyNavOutMsgRecC = module.smallBodyNavOutMsgC.recorder()
unitTestSim.AddModelToTask(unitTaskName, smallBodyNavOutMsgRecC)
asteroidEphemerisOutMsgRec = module.asteroidEphemerisOutMsg.recorder()
unitTestSim.AddModelToTask(unitTaskName, asteroidEphemerisOutMsgRec)
unitTestSim.InitializeSimulation()
unitTestSim.ConfigureStopTime(macros.sec2nano(10.))
unitTestSim.ExecuteSimulation()
x_hat = smallBodyNavOutMsgRec.state
x_hat_c_wrapped = smallBodyNavOutMsgRecC.state
true_x_hat = np.array([[1.33666664e+03, 1.18333330e+03, 1.00333330e+03, -4.77594532e-06,
1.33332617, -6.10976335e-06, 1.13333333e-01, 0.00000000,
0.00000000, 0.00000000, 0.00000000, 0.00000000]])
testFailCount, testMessages = unitTestSupport.compareArray(
true_x_hat, np.array([x_hat[-1,:]]), 0.1, "x_hat",
testFailCount, testMessages)
testFailCount, testMessages = unitTestSupport.compareArray(
true_x_hat, np.array([x_hat_c_wrapped[-1,:]]), 0.1, "x_hat_c_wrapped",
testFailCount, testMessages)
plt.figure(1)
plt.clf()
plt.figure(1, figsize=(7, 5), dpi=80, facecolor='w', edgecolor='k')
plt.ticklabel_format(useOffset=False)
plt.plot(navTransOutMsgRec.times() * 1.0E-9, x_hat[:,0], label='x-pos')
plt.plot(navTransOutMsgRec.times() * 1.0E-9, x_hat[:,1], label='y-pos')
plt.plot(navTransOutMsgRec.times() * 1.0E-9, x_hat[:,2], label='z-pos')
plt.legend(loc='upper left')
plt.xlabel('Time (s)')
plt.ylabel('r_BO_O (m)')
plt.title('Estimated Relative Spacecraft Position')
plt.figure(2)
plt.clf()
plt.figure(2, figsize=(7, 5), dpi=80, facecolor='w', edgecolor='k')
plt.plot(navTransOutMsgRec.times() * 1.0E-9, x_hat[:,3], label='x-vel')
plt.plot(navTransOutMsgRec.times() * 1.0E-9, x_hat[:,4], label='y-vel')
plt.plot(navTransOutMsgRec.times() * 1.0E-9, x_hat[:,5], label='z-vel')
plt.legend(loc='upper left')
plt.xlabel('Time (s)')
plt.ylabel('v_BO_O (m/s)')
plt.title('Estimated Spacecraft Velocity')
plt.figure(5)
plt.clf()
plt.figure(5, figsize=(7, 5), dpi=80, facecolor='w', edgecolor='k')
plt.plot(navTransOutMsgRec.times() * 1.0E-9, x_hat[:,6], label='s1')
plt.plot(navTransOutMsgRec.times() * 1.0E-9, x_hat[:,7], label='s2')
plt.plot(navTransOutMsgRec.times() * 1.0E-9, x_hat[:,8], label='s3')
plt.legend(loc='upper left')
plt.xlabel('Time (s)')
plt.ylabel('sigma_AN (rad)')
plt.title('Estimated Asteroid Attitude')
plt.figure(6)
plt.clf()
plt.figure(6, figsize=(7, 5), dpi=80, facecolor='w', edgecolor='k')
plt.plot(navTransOutMsgRec.times() * 1.0E-9, x_hat[:,9], label='omega1')
plt.plot(navTransOutMsgRec.times() * 1.0E-9, x_hat[:,10], label='omega2')
plt.plot(navTransOutMsgRec.times() * 1.0E-9, x_hat[:,11], label='omega3')
plt.legend(loc='upper left')
plt.xlabel('Time (s)')
plt.ylabel('omega_AN_A (rad/s)')
plt.title('Estimated Asteroid Rate')
if show_plots:
plt.show()
if testFailCount == 0:
print("PASSED: " + module.ModelTag)
else:
print(testMessages)
return [testFailCount, "".join(testMessages)]
if __name__ == "__main__":
test_smallBodyNavEKF(True)