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https://github.com/eProsima/px4_to_ros

ROS2/ROS packages for communicate PX4 with ROS
https://github.com/eProsima/px4_to_ros

Last synced: 25 days ago
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ROS2/ROS packages for communicate PX4 with ROS

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README 

        
PX4-FastRTPS-ROS

================



.. image:: doc/PX4-to-ros.png



This proof of concept aims to extend the `bridge PX4-FastRTPS `_ to **ROS** and test how the exchange of information works between nodes of PX4 and ROS. The PoC has been implemented and tested in a **PIXracer** for the PX4 side and a couple of **PC running Ubuntu 16.04** for micro RTPS agent, ROS2-ROS bridge and the ROS node.



The PoC has been performed over a single message **sensor combined** for the sake of simplicity.



Scheme

------



.. image:: doc/complete_loop.png



The scheme has 5 nodes involved as shown in the image above:



- **uORB**: This node is the representation of the publisher(s) that send, in this case, sensor combined messages through uORB protocol.

- **micrortps_client** is the node that get the information from uORB world, translate it and transmit to the next node in a serialization format understandable for the micro RTPS side of wich is part.

- **micrortps_agent** as a full member of the DDS world inject the received information publishing the message in the **sensor_combined_topic**.

- **static_bridge** is the node of ROS2 (part of the ros1_bridge package) that listen directly whitout previous translation the topic (taking advantage of use of the same RTPS protocol internally) and pass it from ROS 2 to ROS 1.

- **sc_ros1_listener** a very simple ROS node that listen to the well formed ROS topic, print the info on the screen and publish back into a new topic **sensor_combined_topic_back**.



**NOTE**: The same path is followed in reverse from ROS to PX4 for latency estimation.



Requierements

-------------



- **PX4-Fast RTPS brigde**: its necessary work with the `eProsima PX4/Firmware fork `_, please see the `README `_

- **ROS2**: Install `ROS2 `_ with the latest update of its packages from the master branch of `this repository `_.

- **ROS from sources**: Install `ROS `_ from sources (we use **kinetic** distro).



PX4 side: micro RTPS client

---------------------------



The code of the application that will run in to PX4 side will be found in **microRTPS_client** folder. To use this code replaces the original one from the client, please see the **PX4 Firmware** section in the `README `_ in case of doubt.



Fast RTPS side: micro RTPS agent

--------------------------------



The code of the application that will run as micro RTPS agent will be found in **microRTPS_agent** folder. To use this code replaces the original one from the agent, please see the **Fast RTPS (Raspberry PI application)** section in the `README `_ in case of doubt.



ROS side

--------



We need to add two packages to our ROS workspace. For that copy them:



.. code-block:: bash



    $ cd /path/to/px4_to_ros

    $ cp -r px4_msgs_ros1 /path/to/ros1/workspace/src/px4_msgs

    $ cp -r sensor_combined_ros1 /path/to/ros1/workspace/src/



Compile the packages using:



.. code-block:: bash



    $ catkin_make_isolated --pkg px4_msgs --install -DCMAKE_BUILD_TYPE=Release

    $ catkin_make_isolated --pkg sensor_combined_ros1 --install -DCMAKE_BUILD_TYPE=Release



For launch the application we need to launch in first place **roscore** in a separate shell:



.. code-block:: bash



    $ source /path/to/ros1/workspace/install_folder/setup.bash

    $ roscore



Now, you can run the listener application with:



.. code-block:: bash



    $ source /path/to/ros1/workspace/install_folder/setup.bash

    $ rosrun sensor_combined_ros1 sc_ros1_listener



ROS2 side

---------



In order to run the ROS2 to ROS1 bridge, you have to add one package and modify other (**ros1_bridge** package) in your ROS2 worskpace. The package **px4_msgs** generates all the PX4 messages that are actually supported. To use, copy in this way:



.. code-block:: bash



    $ cd /path/to/px4_to_ros

    $ cp -r px4_msgs_ros2 /path/to/ros2/workspace/src/ros2/px4_msgs

    $ cp -r ros1_bridge /path/to/ros2/workspace/src/ros2/



Compile the package px4_msgs with ament using:



.. code-block:: bash



    $ ament build --symlink-install --only px4_msgs



compile the bridge, please see `Building the bridge from source `_



Now, you can run the bridge application with:



.. code-block:: bash



    $ source /path/to/ros1/workspace/install_folder/setup.bash

    $ source /path/to/ros2/workspace/install_folder/setup.bash

    $ static_bridge



Roscore: working in several machines

------------------------------------



In due we only need one instance of *roscore* runnig we need to make some adjustenments to work in separate machines:



Machine that runs *roscore* need to define:



.. code-block:: bash



    $ export ROS_MASTER_URI=http://localhost:11311

    $ export ROS_HOSTNAME=



Machine that **NOT** run *roscore* need to define:



.. code-block:: bash



    $ export ROS_MASTER_URI=http://:11311

    $ export ROS_HOSTNAME=