forked from skulumani/asteroid_dumbbell
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inertial_driver.py
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/
inertial_driver.py
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from __future__ import absolute_import, division, print_function, unicode_literals
import dynamics.asteroid as asteroid
import dynamics.dumbbell as dumbbell
import kinematics.attitude as attitude
from visualization import plotting
from eom_comparison import transform
import numpy as np
from scipy import integrate
import argparse
import pdb
# valid initial condtions for castalia
# defined in the asteroid fixed frame
periodic_pos = np.array([1.495746722510590,0.000001002669660,0.006129720493607])
periodic_vel = np.array([0.000000302161724,-0.000899607989820,-0.000000013286327])
AbsTol = 1e-9
RelTol = 1e-9
def inertial_eoms_driver(initial_state, time, ast, dum):
"""ODEINT Inertial EOMs driver
This function will simulate the inertial equations of motion using
scipy.integrate.odeint and then convert them into the inertial and
asteroid frames.
Parameters
----------
initial_state - (18,) numpy ndarray representing the initial state of the dumbbell
pos - initial_state[0:3] in km position of the dumbbell with respect to the
asteroid and defined in the inertial frame
vel - initial_state[3:6] in km/sec is the velocity of dumbbell wrt the asteroid
and defined in the inertial frame
R - initial_state[6:15] rotation matrix which converts vectors from the dumbbell frame to
the inertial frame
w - state[15:18] rad/sec angular velocity of the dumbbell wrt inertial frame and
defined in the dumbbell frame
time - (n,) numpy ndarray representing the simulation time span
ast - asteroid object instance
dum - dumbbell object instance
Returns
-------
time - (n,) numpy ndarray time vector. Same as the input
inertial_state - (n,18) ndarray with the simulation results represented in the inertial frame
pos - inertial_state[0:3] in km position of the dumbbell with respect to the
asteroid and defined in the inertial frame
vel - inertial_state[3:6] in km/sec is the velocity of dumbbell wrt the asteroid
and defined in the inertial frame
R - inertial_state[6:15] rotation matrix which converts vectors from the dumbbell frame to
the inertial frame
w - inertial_state[15:18] rad/sec angular velocity of the dumbbell wrt inertial frame and
defined in the inertial frame
asteroid_state - (n,18) ndarray with the simulation results represented in the asteroid frame
pos - asteroid_state[0:3] in km position of the dumbbell with respect to the
asteroid and defined in the asteroid frame
vel - asteroid_state[3:6] in km/sec is the velocity of dumbbell wrt the asteroid
and defined in the asteroid frame
R - asteroid_state[6:15] rotation matrix which converts vectors from the dumbbell frame to
the asteroid frame
w - asteroid_state[15:18] rad/sec angular velocity of the dumbbell wrt inertial frame and
defined in the asteroid frame
body_state - (n,18) ndarray with the simulation results represented in the inertial frame
pos - asteroid_state[0:3] in km position of the dumbbell with respect to the
asteroid and defined in the inertial frame
vel - asteroid_state[3:6] in km/sec is the velocity of dumbbell wrt the asteroid
and defined in the inertial frame
R - asteroid_state[6:15] rotation matrix which converts vectors from the dumbbell frame to
the inertial frame
w - asteroid_state[15:18] rad/sec angular velocity of the dumbbell wrt inertial frame and
defined in the dumbbell frame
This output is exactly what dum.eoms_inertial will output without any alduteration
"""
body_state = integrate.odeint(dum.eoms_inertial, initial_state, time, args=(ast,), atol=AbsTol, rtol=RelTol)
# convert to inertial and asteroid frames
inertial_state = transform.eoms_inertial_to_inertial(time, body_state, ast, dum)
asteroid_state = transform.eoms_inertial_to_asteroid(time, body_state, ast, dum)
return (time, inertial_state, asteroid_state, body_state)
def compute_energy(file_name):
with np.load(file_name, allow_pickle=True) as data:
ast_name = data['ast_name']
num_faces = data['num_faces']
time = data['time']
body_state = data['body_state']
dum = data['dum'][()]
ast = data['ast'][()]
KE, PE = dum.inertial_energy(time,body_state,ast)
return KE, PE
def inertial_eoms_energy_behavior(initial_state, time, ast, dum):
"""See \Delta E for varying tolerances of the ODE function
"""
tol_array = np.logspace(-4,-12,9)
time_dict = {}
body_state_dict = {}
inertial_state_dict = {}
asteroid_state_dict = {}
KE_dict = {}
PE_dict = {}
for tol in tol_array:
print('Tolerance - %4.2e' % tol)
(_, inertial_state, asteroid_state, body_state) = inertial_eoms_driver(initial_state, time, ast, dum)
KE, PE = dum.inertial_energy(time, body_state, ast)
time_dict[str(tol)] = time
KE_dict[str(tol)] = KE
PE_dict[str(tol)] = PE
body_state_dict[str(tol)] = body_state
inertial_state_dict[str(tol)] = inertial_state
asteroid_state_dict[str(tol)] = asteroid_state
return (time_dict,KE_dict, PE_dict, body_state_dict, inertial_state_dict, asteroid_state_dict)
def inertial_sim_plotter(file_name, mode):
"""Plot the simulation results
"""
# load the data
with np.load(file_name, allow_pickle=True) as data:
if mode == 0:
ast_name = data['ast_name']
num_faces = data['num_faces']
time = data['time']
body_state = data['body_state']
dum = data['dum'][()]
ast = data['ast'][()]
KE = data['KE']
PE = data['PE']
# compute the
e_fig = plotting.plt.figure()
traj_fig = plotting.plt.figure()
plotting.plot_energy(time,KE, PE, e_fig)
# plotting.animate_inertial_trajectory(time, state, ast, dum, file_name[:-4])
elif mode == 1:
time_dict = data['time_dict'][()]
KE_dict = data['KE_dict'][()]
PE_dict = data['PE_dict'][()]
e_fig = plotting.plt.figure()
for tol in time_dict:
E = KE_dict[tol] + PE_dict[tol]
Ediff = np.absolute(E - E[0])
# print out some useful statistics
print("Tol - %s, DeltaE - %4e" % (tol, E[-1]))
plotting.plt.plot(time_dict[tol], Ediff, label=tol)
plotting.plt.legend()
else:
print("Incorrect mode.")
return 1
plotting.plt.show()
if __name__ == '__main__':
parser = argparse.ArgumentParser(description='Inertial EOMs simulator for a dumbbell around an asteroid')
parser.add_argument('ast_name', help="String - asteroid name: castalia or itokawa", type=str)
parser.add_argument('num_faces', help='Integer - Number of faces in polyhedron model', type=int)
parser.add_argument('tf', help='Float - Terminal time for simulation', type=float)
parser.add_argument('num_steps', help='Float - Number of steps in integration', type=float)
parser.add_argument('file_name', help='String - Filename for npz archive', type=str)
parser.add_argument("-m", "--mode", type=int, choices=[0, 1],
help="Choose which inertial energy mode to run. 0 - inertial energy, 1 - \Delta E behavior")
args = parser.parse_args()
print("Starting the simulation...")
# instantiate the asteroid and dumbbell objects
ast = asteroid.Asteroid(args.ast_name, args.num_faces)
dum = dumbbell.Dumbbell(m1=500, m2=500, l=0.003)
# initialize simulation parameters
time = np.linspace(0, args.tf, args.num_steps)
initial_pos = periodic_pos # km for center of mass in body frame
initial_vel = periodic_vel + attitude.hat_map(ast.omega*np.array([0,0,1])).dot(initial_pos)
initial_R = attitude.rot2(0).reshape(9) # transforms from dumbbell body frame to the inertial frame
initial_w = np.array([0.01, 0.01, 0.01])
initial_state = np.hstack((initial_pos, initial_vel, initial_R, initial_w))
# echo back all the input parameters
print("This will run a long simulation with the following parameters!")
print(" ast_name - %s" % args.ast_name)
print(" num_faces - %s" % args.num_faces)
print(" tf - %s" % args.tf)
print(" num_steps - %s" % args.num_steps)
print(" file_name - %s" % args.file_name)
print("")
if args.mode == 0:
(_, inertial_state, asteroid_state, body_state) = inertial_eoms_driver(initial_state, time, ast, dum)
print("Finished the simulation...")
print("Saving to npz file")
np.savez(args.file_name,inertial_state=inertial_state, time=time, asteroid_state=asteroid_state,
body_state=body_state, ast_name=args.ast_name, num_steps=args.num_steps,tf=args.tf, num_faces=args.num_faces,
ast=ast, dum=dum)
print("Now working to calculate the KE/PE of the simulation!")
KE, PE = compute_energy(args.file_name)
print("Finished with energy computations!")
np.savez('inertial_energy_' + args.file_name, args.file_name,inertial_state=inertial_state, time=time, asteroid_state=asteroid_state,
body_state=body_state, ast_name=args.ast_name, num_steps=args.num_steps,tf=args.tf, num_faces=args.num_faces,
ast=ast, dum=dum, KE=KE, PE=PE)
print("All finished!")
elif args.mode == 1:
print("We're running many simulations wiht varying tolerances.")
(time_dict, KE_dict, PE_dict, body_state_dict, inertial_state_dict, asteroid_state_dict) \
= inertial_eoms_energy_behavior(initial_state, time, ast, dum)
print("Finished with simulations. Now saving to data file")
np.savez('inertial_energy_behavior_' + args.file_name, KE_dict=KE_dict,
PE_dict=PE_dict, time_dict=time_dict, ast_name=args.ast_name, num_steps=args.num_steps,
tf=args.tf, num_faces=args.num_faces, body_state_dict=body_state_dict,
inertial_state_dict=inertial_state_dict, asteroid_state_dict=asteroid_state_dict,
ast=ast, dum=dum)
print("All finished!")
else:
print("Missing mode argument")