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| # Robotics using ROS | ||
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| [ROS](http://www.ros.org/) (Robot Operating System) is a general purpose robotics library that can be used with PX4 for offboard control. It uses the [MAVROS](../ros/mavros_installation.md) node to communicate with PX4 via MAVLink. | ||
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| This section contains topics about using ROS for offboard control with PX4. | ||
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| # Gazebo Simulation | ||
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| [Gazebo](http://gazebosim.org) is a powerful 3D simulation environment for autonomous robots that is particularly suitable for testing object-avoidance and computer vision. It can also be used for [multi-vehicle simulation](../simulation/multi-vehicle-simulation.md) and is commonly used with [ROS](../simulation/ros_interface.md), a collection of tools for automating vehicle control. | ||
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| **Supported Vehicles:** Quad ([Iris](../airframes/airframe_reference.md#copter_quadrotor_wide_3dr_iris_quadrotor) and [Solo](../airframes/airframe_reference.md#copter_quadrotor_x_3dr_solo), Hex (Typhoon H480), [Generic quad delta VTOL](../airframes/airframe_reference.md#vtol_standard_vtol_generic_quad_delta_vtol), Tailsitter, Plane, Rover, Submarine (coming soon!) | ||
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| > **Tip** See [Simulation](/simulation/README.md) for general information about simulators, the simulation environment and available simulation configuration (e.g. supported vehicles). | ||
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| {% youtube %}https://www.youtube.com/watch?v=qfFF9-0k4KA&vq=hd720{% endyoutube %} | ||
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| MAVLink-->SITL; | ||
| {% endmermaid %} | ||
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| ## Installation | ||
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| > **Tip** If you plan to use PX4 with ROS you should instead [follow the instructions here](../simulation/ros_interface.md) to install Gazebo as part of ROS! Note that we install Gazebo7 with ROS, as this is the default compatible version. | ||
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| Gazebo 8 setup in included in our standard build instructions: | ||
| - **macOS:** [Development Environment on Mac](http://localhost:4000/en/setup/dev_env_mac.html) | ||
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Collaborator
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There was a problem hiding this comment. @TSC21 Does macOS installer also include ROS Kinetic? If so, does it install Gazebo 7 (the default) or Gazebo 8 (preferred).
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There was a problem hiding this comment. Note also that I've dropped the mention of gazebo 6. We prefer gazebo 8 as standalone and for ROS we use whatever it default to.
Member
There was a problem hiding this comment. I can't actually confirm that since I don't have a Mac... |
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| - **Linux:** [Development Environment on Linux > jMAVSim/Gazebo Simulation](../setup/dev_env_linux.md#jmavsimgazebo-simulation) | ||
| - **Windows:** Not supported. | ||
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| Additional installation instructions can be found on [gazebosim.org](http://gazebosim.org/tutorials?cat=guided_b&tut=guided_b1). | ||
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| ## Running the Simulation | ||
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| You can run a simulation by starting PX4 SITL and gazebo with the airframe configuration to load (multicopters, planes, VTOL, optical flow and multi-vehicle simulations are supported). | ||
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| The easiest way to do this is to open a terminal in the root directory of the PX4 *Firmware* repository and call `make` for the targets as shown in the following sections. | ||
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| > **Tip** You can use the [instructions below](#start_px4_sim_separately) to keep Gazebo running and only re-launch PX4. This is quicker than restarting both. | ||
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| <span></span> | ||
| > **Tip** For the full list of build targets run `make posix list_vmd_make_targets` (and filter on those that start with `gazebo_`). | ||
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| ### Quadrotor | ||
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| make posix_sitl_default gazebo_hippocampus | ||
| ``` | ||
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| ## Taking it to the Sky | ||
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| > **Note** Please refer to the [Installing Files and Code](../setup/dev_env.md) guide if you run into any errors. | ||
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| This will bring up the PX4 shell: | ||
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| pxh> commander takeoff | ||
| ``` | ||
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| > **Note** Joystick or thumb-joystick support [is available](../simulation/README.md#joystickgamepad-integration). | ||
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| ## Set custom takeoff location | ||
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| make posix gazebo | ||
| ``` | ||
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| ## Starting Gazebo and PX4 separately {#start_px4_sim_separately} | ||
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| For extended development sessions it might be more convenient to start Gazebo and PX4 separately or even from within an IDE. | ||
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| # Interfacing the Simulation to ROS | ||
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| [ROS](../ros/README.md) (Robot Operating System) is a general purpose robotics library that can be used with the PX4 flight stack and also (optionally) with the Gazebo simulator. It uses the [MAVROS](../ros/mavros_installation.md) MAVLink node to communicate with PX4. | ||
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| The diagram below shows the *standard* [PX4 simulation environment](../simulation/README.md#sitl-simulation-environment). PX4 communicates with the simulator (e.g. Gazebo) to receive sensor data from the simulated world and send motor and actuator values. It communicates with the GCS and Offboard API to send telemetry from the simulated environment and receive commands. | ||
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| The ROS/Gazebo integration with PX4 follows the pattern above. The only *slight* difference being that ROS initiates the connection on port 14557, while it is more typical for an offboard API to listen for connections on UDP port 14540. | ||
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| ## Installing Gazebo for ROS | ||
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| The easiest way to setup PX4 simulation with ROS on Ubuntu Linux is to use the standard installation script that can be found at [Development Environment on Linux > Gazebo with ROS](../setup/dev_env_linux.md#gazebo-with-ros). The script installs everything you need: PX4, ROS "Kinetic", the Gazebo 7 simulator, and [MAVROS](../ros/mavros_installation.md). | ||
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| > **Note** The script follows the [standard ROS "Kinetic" installation instructions](http://wiki.ros.org/kinetic/Installation/Ubuntu), which include Gazebo 7. Installation of ROS Kinetic for other platforms is covered in the [ROS Wiki here](http://wiki.ros.org/kinetic/Installation). | ||
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| ## Launching ROS/Simulation | ||
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| The command below can be used to launch the simulation and connect ROS to it via [MAVROS](../ros/mavros_installation.md), where `fcu_url` is the IP / port of the computer running the simulation: | ||
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| ```sh | ||
| roslaunch mavros px4.launch fcu_url:="udp://:[email protected]:14557" | ||
| ``` | ||
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| To connect to localhost, use this URL: | ||
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| ```sh | ||
| roslaunch mavros px4.launch fcu_url:="udp://:[email protected]:14557" | ||
| ``` | ||
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| > **Tip** It can be useful to call *roslaunch* with the `-w` (warn) and/or `-v` (verbose) in order to get warnings about missing dependencies in your setup. For example: | ||
| ```sh | ||
| roslaunch mavros px4.launch fcu_url:="udp://:[email protected]:14557" | ||
| ``` | ||
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| ## Launching Gazebo with ROS Wrappers | ||
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Collaborator
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There was a problem hiding this comment. @TSC21 So how I interpret this is that rather than having ROS get rangefinder information from PX4 it can get it from gazebo.
Member
There was a problem hiding this comment. The PX4 ROS implementation (which is an active part of SITL) has everything built in to receive and publish data in the ROS framework - but I actually don't know what is happening there cause there seems to be some data handled as ROS msgs, other as Gazebo msgs, while there is data also being handled as Mavlink msgs. @bkueng maybe you can clarify that?
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There was a problem hiding this comment.
Sorry, since I don't use ROS I don't know the internals on that.
Member
There was a problem hiding this comment. Ok but then whoever wrote the PX4 ROS implementation can give a hand here?
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There was a problem hiding this comment. This all sounds very inconsistent. It would be useful to understand, but I doubt we'll get a timely answer on this point. OK if I create a separate issue that this section needs update and merge the rest?
Member
There was a problem hiding this comment. What does require a clarification is how the PX4 ROS implementation is done, what it accepts and how it can be applied generally (if it can be pulled out of the SITL sim environment for example).
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Author
There was a problem hiding this comment. Yes. I have posted a question #399 for that. |
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| The Gazebo simulation can be modified to integrate sensors publishing directly to ROS topics e.g. the Gazebo ROS laser plugin. To support this feature, Gazebo must be launched with the appropriate ROS wrappers. | ||
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| There are ROS launch scripts available to run the simulation wrapped in ROS: | ||
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| * [posix_sitl.launch](https://github.com/PX4/Firmware/blob/master/launch/posix_sitl.launch): plain SITL launch | ||
| * [mavros_posix_sitl.launch](https://github.com/PX4/Firmware/blob/master/launch/mavros_posix_sitl.launch): SITL and MAVROS | ||
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| To run SITL wrapped in ROS the ROS environment needs to be updated, then launch as usual: | ||
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| (optional): only source the catkin workspace if you compiled MAVROS or other ROS packages from source: | ||
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| ```sh | ||
| cd <Firmware_clone> | ||
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| Include one of the above mentioned launch files in your own launch file to run your ROS application in the simulation. | ||
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| ### What's Happening Behind the Scenes | ||
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| This section shows how the *roslaunch* instructions provided previously actually work (you can follow them to manually launch the simulation and ROS). | ||
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| First start the simulator using the command below: | ||
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| ```sh | ||
| no_sim=1 make posix_sitl_default gazebo | ||
| ``` | ||
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| The console will look like this: | ||
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| ```sh | ||
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@TSC21 I would like to move this OUT of simulation and into the ROS section. My reasoning is that even though ROS can be used with a simulator, it can also be used stand alone. The topic name would also change to something like "ROS with Gazebo Simulation". Note that I have updated the Gazebo doc to better link to this ROS doc too.
Does this make sense to you?
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Makes sense to me
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OK, done in 108d2ce