ROSbotran architecture
======================

This tutorial presents the process used to execute and operate a
Robotran project from ROS by connecting a laptop and a Raspberry. The
final output consists of two ROS packages (named *ros\_rob* for the
Robotran project and *ros\_rasp* for the Raspberry). These two packages
can be downloaded `ros\_rob <./src_rob>`__ and
`ros\_rasp <./src_rasp>`__.

.. figure:: figure/architecture.PNG
   :alt: Architecture

   Architecture
The objective of this page is to present how these two packages work
together. After that, each package will be deeply presented in the next
pages and instructions to use them will be given.

*ros\_rob* package
------------------

This package follows the classic ROS package architecture:

.. figure:: figure/ros_package_archi.png
   :alt: ROS Package Architecture

   ROS Package Architecture
**CMakeLists.txt** file:
~~~~~~~~~~~~~~~~~~~~~~~~

This lists the compilation instructions for the *ros\_rob* package and
includes also a link to the *CMakeLists* of a used Robotran project.
This latter will then be read by the catkin ROS compiler which will
generate a ROS executable from Robotran. The user needs to specify in
this file the paths to *mbsysc*, *ROS* and *Pthread* librairies (see
after).

**launch** folder:
~~~~~~~~~~~~~~~~~~

The *launch* files allow to run multiple ROS nodes and tools in one
command line when you want to execute a complete project.

**msg** folder:
~~~~~~~~~~~~~~~

It contains .msg files that allow you to create personalized messages
for ROS topics in order to transport our data (in the case of Robotran
it will be mainly positions, speeds, joint forces).

**src** folder:
~~~~~~~~~~~~~~~

It contains the entire Robotran project(s) (without the *build* folder).

**main** file (in the Robotran project inside *src* folder):
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Uses several **threads**

1. Executes the "classic" Robotran *main*, namely: loading the model
   static and quasi-static equilibria, modal analysis and direct
   dynamics (or inverse).

2. Creates a ROS Publisher object to provide the necessary functions to
   publish the data generated by Robotran on a topic.

3. Creates a ROS Subscriber object to collect data from a topic and to
   exploit them in Robotran.

.. figure:: figure/MultiThreadMainRob.png
   :alt: Multithreading in main

   Multithreading in main
*ros\_rasp* package
-------------------

This is a ROS package which receives/publishes data for a Robotran
project. Running this package alone has no interest but it can be used
along with *ros\_rob*.

In this tutorial, we present an example where you can drive a car with
the left and right keyboard arrows and, thanks to a ROS topic, publish
the torque which will be applied in the steering wheel. The interest is
that you can run the *ros\_rasp* package on an other device (which has
ROS installed on it and a complete, bi-directional connectivity with the
first device by *SSH* communication), for example a `Raspberry
Pi <https://www.raspberrypi.org/>`__. Now you are able to publish data
to Robotran from an external device and also receive data from Robotran
to this external device.

This is **ROSbotran** ;-)