How to simulate multiple satellites

1. Overview

S2E can simulate multiple satellites.
This document describes how to simulate multiple satellites.
For the sample codes, please see s2e-user-example/sample/how-to-simulate-multiple-satellites.
The supported version of this document
- Please confirm that the version of the documents and s2e-core are compatible.

2. How to add a new satellite

Edit ini files
1. Add ini files for the new satellite.
  - satellite.ini, disturbance.ini, local_environment.ini, structure.ini are needed.
2. Register the ini file for the new satellite in simulation_base.ini
  - The arguments of satellite_file are used as satellite ID in simulation.
```
[SIMULATION_SETTINGS]
number_of_simulated_spacecraft = 2
spacecraft_file(0) = INI_FILE_DIR_FROM_EXE/user_satellite.ini
spacecraft_file(1) = INI_FILE_DIR_FROM_EXE/user_satellite2.ini
```
Edit source code
1. Add new UserSatellite instances to Case members in user_case.hpp.
```
UserSatellite *spacecraft0_;  //!< Instance of spacecraft
UserSatellite *spacecraft1_;  //!< Instance of spacecraft
```
2. Edit user_case.cpp to copy the spacecraft related codes as the sample code.
  - Please see the sample code for more details.
Build and execute the s2e-user
You can see the log spacecraft_angular_velocity_b_x[rad/s] twice. The first one is the angular velocity of satellite 0, and the second one is the angular velocity of satellite 1 in the log file.

3. Advanced usage

In the sample, the satellite0_ and the satellite1_ are completely the same, but users can change the settings of these satellites with editing the ini files.
- Users can change the orbit, initial attitude, satellite structure and so on.
Users also can set the different components for the satellite 0 and 1, when users define different UserSatellite and UserComponents classes.
The document to use relative information will be written.
Users can also refer the S2E-FF repository.