<!DOCTYPE module SYSTEM "module.dtd">
<module name="fdm_gazebo" dir="fdm">
<doc>
<description>
Gazebo backend for NPS simulator
NPS doc: http://wiki.paparazziuav.org/wiki/NPS
Usage:
1. Make sure gazebo 7 or 8 is installed. (sudo apt-get install gazebo8 libgazebo8-dev)
2. Prepare the Gazebo world and model:
a) Prepare the UAV model (see conf/simulator/gazebo/models/ardrone/):
Place the aircraft model in the conf/simulator/gazebo/models/
folder, this folder is added to Gazebo's search path 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.
b) Prepare the world (see conf/simulator/gazebo/worlds/ardrone.world).
Pay attention to the following:
The real-time update rate should be set to zero, as this 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>
3. Prepare the airframe file (see examples/ardrone2_gazebo.xml):
a) Select Gazebo as the FDM (Flight Dynamics Model)
<target name="nps" board="pc">
<module name="fdm" type="gazebo"/>
</target>
b) 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.
c) In the same section, bypass the AHRS and INS as these are not
supported yet:
<section name="SIMULATOR" prefix="NPS_">
...
<define name="BYPASS_AHRS" value="1"/>
<define name="BYPASS_INS" value="1"/>
...
<section>
d) If required, enable video thread simulation:
<section name="SIMULATOR" prefix="NPS_">
...
<define name="SIMULATE_VIDEO" value="1"/>
...
<section>
e) If required, 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 nps. At the moment, most of
the modules that depend on video_thread are only built when ap is
selected as the target. As a quick fix, try to remove the target
attribute from the makefile element in the module xml, e.g.:
<makefile target="ap"> ---> <makefile>
</description>
</doc>
<header/>
<makefile target="nps">
<raw>
nps.CXXFLAGS += $(shell pkg-config gazebo --cflags)
nps.LDFLAGS += $(shell pkg-config gazebo --libs)
</raw>
<file name="nps_fdm_gazebo.cpp" dir="nps"/>
</makefile>
</module>
1.8.8 
