Overview

CI status	Debian package

Multi-drone PX4 SITL setup using Gazebo and ROS2. Generally follows https://docs.px4.io/main/en/sim_gazebo_gz/, but uses custom bringup scripts which serve as a showcase of https://github.com/asherikov/cdinit.

Workspace documentation is at http://www.sherikov.net/px4ws/.

Usage

Building

• Build px4sitl master package. Workspace is designed to be used with https://github.com/asherikov/ccws, but basic colcon build should work too.

• Dependencies can be installed with rosdep except a few PX4 python dependencies that are installed with cmake during build step.

Binary package

• Go to cloudsmith package repo, add new apt source, and run apt update.
• sudo apt install px4ws--reldebug--all
• source /opt/px4ws/px4ws__reldebug__all/setup.bash
• Launch as explained below.

Running

• Run px4sitl.sh -w walls -d 4001 "0,1.0,0,0,0,0" -d 4004 "0,-5.0,0,0,0,0" where -w specifies world ('default' if not set), -d specifies a drone model id and its location (x,y,z,r,p,y). Numerical ids can be found in a table at https://docs.px4.io/main/en/sim_gazebo_gz/.
• px4sitl.sh also supports headless mode, which is enabled by passing -H flag.
• Terminate by closing Gazebo gui, or with cdinit.sh shutdown.

cdinit services

All components are started using dinit service files located in px4sitl/cdinit_services/, see https://github.com/davmac314/dinit, https://github.com/asherikov/cdinit provides a cmake wrapper for dinit and helper scripts. Shell scripts are primarily used to setup environment and working directories.

Example

• Start px4sitl.sh -w walls -d 4001 "0,1.0,0,0,0,0" -d 4004 "0,-5.0,0,0,0,0"
• List services cdinit.sh list | sort to get something like

# dummy "boot" service
[[+]     ] cdinit_main
# Gazebo gui
[[+]     ] px4sitl_gz_gui (pid: XXX)
# PX4 instances, number after @ symbol is a corresponding system id
[[+]     ] px4sitl_px4@0 (pid: XXX)
[[+]     ] px4sitl_px4@1 (pid: XXX)
# logging services, cdinit_log helper adds timestamps
[{+}     ] cdinit_log@px4sitl_dds_agent (pid: XXX)
[{+}     ] cdinit_log@px4sitl_gz_clock (pid: XXX)
[{+}     ] cdinit_log@px4sitl_gz_gui (pid: XXX)
[{+}     ] cdinit_log@px4sitl_gz_headless (pid: XXX)
[{+}     ] cdinit_log@px4sitl_gz_wait (pid: XXX)
[{+}     ] cdinit_log@px4sitl_px4@0 (pid: XXX)
[{+}     ] cdinit_log@px4sitl_px4@1 (pid: XXX)
# Micro-XRCE-DDS-Agent bridging PX4 and ros2
[{+}     ] px4sitl_dds_agent (pid: XXX)
# Gazebo -> ROS2 simulation clock bridge
[{+}     ] px4sitl_gz_clock (pid: XXX)
# Gazebo simulation core
[{+}     ] px4sitl_gz_headless (pid: XXX)
# Helper service which waits for Gazebo to start
[{+}     ] px4sitl_gz_wait
# Dummy "master" service
[{+}     ] px4sitl_ros

• Location of the log files depends on environment variables, e.g., ROS_LOG_DIR and is printed on startup.
• Terminate using cdinit.sh shutdown. Since all processes are required, termination can also be performed by stopping a particular service, e.g., cdinit.sh stop --force px4sitl_gz_clock.

Service dependency graph

Troubleshooting

• protobuf errors like the following could be caused by multiple Gazebo versions installed in parallel: [libprotobuf ERROR google/protobuf/descriptor_database.cc:121] File already exists in database: gz/msgs/pointcloud.proto
• PX4 fails during automatic takeoff with "Disarmed by auto preflight disarming": make sure that unused parameters in vehicle command message are set to NaN.

TODO

• Is installation of px4/build/ intentional?
• CMakeLists.txt, package.xml should not be installed.