package_setup.md

Package Setup

This setup guide assumes you have installed the Micro XRCE-DDS Agent and PX4 v1.14.0-rc1 as explained in PX4 and ROS 2 setup

1. ROS 2 setup

1.1. Create a workspace

This guide assumes the workspace to be in ~/llc/llc_ws/ but any desired name/location can be used.

mkdir -p ~/llc/llc_ws/src

1.2. Clone the package

cd ~/llc/llc_ws/src
git clone https://github.com/SaxionMechatronics/px4_offboard_lowlevel.git

1.3. Clone px4_msgs

This package has been confirmed to work with a certain commit of px4_msgs, you can obtain this commit like so:

cd ~/llc/llc_ws/src
git clone https://github.com/PX4/px4_msgs.git

cd px4_msgs
# git reset --hard e3d36168a97f0268ab97e626d14858ca644924ef

1.4. Build

cd ~/llc/llc_ws/
colcon build --symlink-install

2. PX4 Setup

2.1. Change set of ROS 2 PX4 topics

Before building PX4 you need to change the list of topics for the μXRCE Client, to do this replace the default topics configuration in PX4-Autopilot/src/modules/uxrce_dds_client/dds_topics.yaml by px4-resources/dds_topics.yaml from this repository.

cp /PATH_TO/src/px4_offboard_lowlevel/px4-resources/dds_topics.yaml PATH_TO/PX4-Autopilot/src/modules/uxrce_dds_client/

2.2. Disable lockstep in PX4

Lockstep needs to be disabled in PX4 and Gazebo to make the simulation run correctly while using thrust/torque commands.

Enter the board config for px4 sitl

make px4_sitl boardconfig

Navigate to Toolchain and enable force disable lockstep

Quit (Q) and save (Y)

Open the gazebo model you will be using for simulation, for example: PX4-Autopilot/Tools/simulation/gazebo-classic/sitl_gazebo-classic/models/iris/iris.sdf.

Change enable_lockstep (line 466) from 1 to 0 like so:

<enable_lockstep>0</enable_lockstep>

2.4 (optional) Remove the asphalt plane from Gazebo-classic default world

I hate it, so here it is:

cp /PATH_TO/src/px4_offboard_lowlevel/px4-resources/empty.world PATH_TO/PX4-Autopilot/Tools/simulation/gazebo-classic/sitl_gazebo-classic/worlds/