Gazebo

Gazebo

The nice sim framework Gazebo from here http://gazebosim.org/ can now be use from withing Paparazzi. Are you doing work on UAS in combination with e.g. Vision based navigation check it out. I might make testing your new work so much simpler.

Be warned, using it can be highly addictive, and might tempt youinto buying a new computer with hight spacification. To be able to use Gaxzebo a very good Video card is needed, considder upgrading you yadware if everything runs to slow.

Installation and use take alook here http://docs.paparazziuav.org/v5.12/module__fdm_gazebo.html

Gazebo backend for NPS NPS simulator

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Installation

We assume you already have Paparazzi installed via the One liner. If Not install Paparzzi first plz. Then come back to this page.

Gazebo Installation=

Steps to install Gazebo

     1. Make sure gazebo 9 is installed. (sudo apt-get install gazebo8 libgazebo8-dev)

Model

Prepare your Gazebo aircraft model (example see conf/simulator/gazebo/models/ardrone/):

Place the aircraft model in the conf/simulator/gazebo/models/ folder, this folder is added to the search path of Gazebo when NPS is launched. Gazebo uses a Front, Left, Up coordinate system for aircraft, so make sure the +x axis points forwards. The model should include a link for each motor with the same names as those listed in NPS_ACTUATOR_NAMES (see below), e.g. 'nw_motor'. Camera links should have the name specified in .dev_name in the

corresponding video_config_t struct, see sw/airborne/boards/pc_sim.h and sw/airborne/modules/computer_vision/video_thread_nps.c.

World

Prepare the world (see conf/simulator/gazebo/worlds/ardrone.world).

NOTE: Pay attention to the following:

The real-time update rate should be set to zero, as the simulation backend is already handled by Paparazzi:

<physics type="ode">
<max_step_size>0.001</max_step_size>
<real_time_update_rate>0</real_time_update_rate><!-- Handled by Paparazzi! -->
</physics>

Spherical coordinates should be provided for navigation. At this moment, there is an issue where Gazebo incorrectly uses a WSU coordinate system instead of ENU. This can be fixed by setting the heading to 180 degrees as shown below:

<spherical_coordinates>
<surface_model>EARTH_WGS84</surface_model>
<latitude_deg>51.9906</latitude_deg>
<longitude_deg>4.37679</longitude_deg>
<elevation>0</elevation>
<heading_deg>180</heading_deg><!-- Temporary fix for issue https://bitbucket.org/osrf/gazebo/issues/2022/default-sphericalcoordinates-frame-should -->
</spherical_coordinates>

Airframe

Enhance your Paparzazzi airframe file to be able to use Gazebo (see examples/ardrone2_gazebo.xml):

Select Gazebo as the FDM (Flight Dynamics Model) by adding it to the aircraft file

<target name="nps" board="pc">
<module name="fdm" type="gazebo"/>
 </target>

Add actuator thrusts and torques to the SIMULATOR section:

<section name="SIMULATOR" prefix="NPS_">
<define name="ACTUATOR_NAMES" value="nw_motor, ne_motor, se_motor, sw_motor" type="string[]"/>
<define name="ACTUATOR_THRUSTS" value="1.55, 1.55, 1.55, 1.55" type="double[]"/>
<define name="ACTUATOR_TORQUES" value="0.155, -0.155, 0.155, -0.155" type="double[]"/>
           ...
         <section>

The thrusts and torques are expressed in SI units (N, Nm) and should be in the same order as the ACTUATOR_NAMES.

In the same section, bypass the AHRS and INS as these are not supported yet, so add this

<section name="SIMULATOR" prefix="NPS_">
...
<define name="BYPASS_AHRS" value="1"/>
<define name="BYPASS_INS" value="1"/>
...
<section>

If you want to use visual based behaviour, enable video thread simulation:

<section name="SIMULATOR" prefix="NPS_">
...
<define name="SIMULATE_VIDEO" value="1"/>
...
<section>

Specify the Gazebo world and aircraft name:

<section name="SIMULATOR" prefix="NPS_">
...
           <define name="GAZEBO_WORLD" value="my_world.world"/>
           <define name="GAZEBO_AC_NAME" value="my_uav"/>
         <section>

   4. Make sure all included modules work with NS. 

At the current state of Paparazzi code (20180206), most of the modules that depend on video_thread are only built when the target ap (autopilot hardware) is selected as the target.

As a quick 'n dirty fix, try to remove the target attribute from the makefile element in the module xml, e.g.:

<makefile target="ap"> ---> <makefile>

It would be great if as a user you would improve this and make a Pull request of your code improvments to the main Paparazzi codebase, TIA

Reality

Never forget... A sim is not reality... validate via testflights in the real world after you think everything you created works perfectly.