.. _scenarioAttitudeFeedbackNoEarth:

scenarioAttitudeFeedbackNoEarth
===============================

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 ``xmera/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