9.2 KiB
Testing with DDS/micro-Ros
Architecture
Ardupilot contains the DDS Client library, which can run as SITL. Then, the DDS application runs a ROS2 node, an EProsima Integration Service, and the MicroXRCE Agent. The two systems communicate can communicate over serial or UDP.
---
title: UDP Loopback
---
graph LR
subgraph Linux Computer
subgraph Ardupilot SITL
veh[sim_vehicle.py] <--> xrceClient[EProsima Micro XRCE DDS Client]
xrceClient <--> port1[udp:2019]
end
subgraph DDS Application
ros[ROS2 Node] <--> agent[Micro ROS Agent]
agent <-->port1[udp:2019]
end
loopback
end
---
title: Hardware Serial Port Loopback
---
graph LR
subgraph Linux Computer
subgraph Ardupilot SITL
veh[sim_vehicle.py] <--> xrceClient[EProsima Micro XRCE DDS Client]
xrceClient <--> port1[devUSB1]
end
subgraph DDS Application
ros[ROS2 Node] <--> agent[Micro ROS Agent]
agent <--> port2[devUSB2]
end
port1 <--> port2
end
Installing Build Dependencies
While DDS support in Ardupilot is mostly through git submodules, another tool needs to be available on your system: Micro XRCE DDS Gen.
-
Go to a directory on your system to clone the repo (perhaps next to
ardupilot
) -
Install java
sudo apt install default-jre
-
Follow instructions here to install the latest version of the generator using Ardupilot's mirror
git clone --recurse-submodules https://github.com/ardupilot/Micro-XRCE-DDS-Gen.git cd Micro-XRCE-DDS-Gen ./gradlew assemble
-
Add the generator directory to $PATH.
# Add this to ~/.bashrc export PATH=$PATH:/your/path/to/Micro-XRCE-DDS-Gen/scripts
-
Test it
cd /path/to/ardupilot microxrceddsgen -version # openjdk version "11.0.18" 2023-01-17 # OpenJDK Runtime Environment (build 11.0.18+10-post-Ubuntu-0ubuntu122.04) # OpenJDK 64-Bit Server VM (build 11.0.18+10-post-Ubuntu-0ubuntu122.04, mixed mode, sharing) # microxrceddsgen version: 1.0.0beta2
⚠️ If you have installed FastDDS or FastDDSGen globally on your system: eProsima's libraries and the packaging system in Ardupilot are not determistic in this scenario. You may experience the wrong version of a library brought in, or runtime segfaults. For now, avoid having simultaneous local and global installs. If you followed the global install section, you should remove it and switch to local install.
Serial Only: Set up serial for SITL with DDS
On Linux, creating a virtual serial port will be necessary to use serial in SITL, because of that install socat.
sudo apt-get update
sudo apt-get install socat
Setup ardupilot for SITL with DDS
Set up your SITL.
Run the simulator with the following command. If using UDP, the only parameter you need to set it DDS_ENABLE
.
Name | Description |
---|---|
DDS_ENABLE | Set to 1 to enable DDS |
SERIAL1_BAUD | The serial baud rate for DDS |
SERIAL1_PROTOCOL | Set this to 45 to use DDS on the serial port |
# Wipe params till you see "AP: ArduPilot Ready"
# Select your favorite vehicle type
sim_vehicle.py -w -v ArduPlane --console -DG --enable-dds
# Enable DDS (both for UDP or Serial)
param set DDS_ENABLE 1
# Only for Serial
param set SERIAL1_BAUD 115
# See libraries/AP_SerialManager/AP_SerialManager.h AP_SerialManager SerialProtocol_DDS_XRCE
param set SERIAL1_PROTOCOL 45
Because DDS_ENABLE
requires a reboot, stop the simulator with ctrl+C and proceed to the next section.
Setup ROS 2 and micro-ROS
Follow the steps to use the microROS Agent
-
Install ROS Humble (as described here)
-
Install geographic_msgs
sudo apt install ros-humble-geographic-msgs
-
Install and run the microROS agent (as descibed here). Make sure to use the
humble
branch.-
Follow the instructions for the following:
- Do "Installing ROS 2 and the micro-ROS build system"
- Skip the docker run command, build it locally instead
- Skip "Creating a new firmware workspace"
- Skip "Building the firmware"
- Do "Creating the micro-ROS agent"
- Source your ROS workspace
- Do "Installing ROS 2 and the micro-ROS build system"
-
Until this PR is merged, ignore the notes about foxy
. It works on humble
.
Using the ROS2 CLI to Read Ardupilot Data
After your setups are complete, do the following:
- Source the ros2 installation
source /opt/ros/humble/setup.bash
Next, follow the associated section for your chosen transport, and finally you can use the ROS 2 CLI.
UDP (recommended for SITL)
- Run the microROS agent
cd ardupilot/libraries/AP_DDS ros2 run micro_ros_agent micro_ros_agent udp4 -p 2019 -r dds_xrce_profile.xml
- Run SITL (remember to kill any terminals running ardupilot SITL beforehand)
# assuming we are using /dev/pts/1 for Ardupilot SITL sim_vehicle.py -v ArduPlane -DG --console --enable-dds
Serial
- Start a virtual serial port with socat. Take note of the two
/dev/pts/*
ports. If yours are different, substitute as needed.socat -d -d pty,raw,echo=0 pty,raw,echo=0 >>> 2023/02/21 05:26:06 socat[334] N PTY is /dev/pts/1 >>> 2023/02/21 05:26:06 socat[334] N PTY is /dev/pts/2 >>> 2023/02/21 05:26:06 socat[334] N starting data transfer loop with FDs [5,5] and [7,7]
- Run the microROS agent
cd ardupilot/libraries/AP_DDS # assuming we are using tty/pts/2 for DDS Application ros2 run micro_ros_agent micro_ros_agent serial -b 115200 -r dds_xrce_profile.xml -D /dev/pts/2
- Run SITL (remember to kill any terminals running ardupilot SITL beforehand)
# assuming we are using /dev/pts/1 for Ardupilot SITL sim_vehicle.py -v ArduPlane -DG --console --enable-dds -A "--uartC=uart:/dev/pts/1"
Use ROS 2 CLI
-
You should be able to see the agent here and view the data output.
$ ros2 node list /Ardupilot_DDS_XRCE_Client $ ros2 topic list -v Published topics: * /ap/battery/battery0 [sensor_msgs/msg/BatteryState] 1 publisher * /ap/clock [rosgraph_msgs/msg/Clock] 1 publisher * /ap/geopose/filtered [geographic_msgs/msg/GeoPoseStamped] 1 publisher * /ap/navsat/navsat0 [sensor_msgs/msg/NavSatFix] 1 publisher * /ap/pose/filtered [geometry_msgs/msg/PoseStamped] 1 publisher * /ap/tf_static [tf2_msgs/msg/TFMessage] 1 publisher * /ap/time [builtin_interfaces/msg/Time] 1 publisher * /ap/twist/filtered [geometry_msgs/msg/TwistStamped] 1 publisher * /parameter_events [rcl_interfaces/msg/ParameterEvent] 1 publisher * /rosout [rcl_interfaces/msg/Log] 1 publisher Subscribed topics: $ ros2 topic hz /ap/time average rate: 50.115 min: 0.012s max: 0.024s std dev: 0.00328s window: 52 $ ros2 topic echo /ap/time sec: 1678668735 nanosec: 729410000 ---
The static transforms for enabled sensors are also published, and can be recieved like so:
ros2 topic echo /ap/tf_static --qos-depth 1 --qos-history keep_last --qos-reliability reliable --qos-durability transient_local --once
In order to consume the transforms, it's highly recommended to create and run a transform broadcaster in ROS 2.
Contributing to AP_DDS library
Adding DDS messages to Ardupilot
Unlike the use of ROS 2 .msg
files, since Ardupilot supports native DDS, the message files follow OMG IDL DDS v4.2.
This package is intended to work with any .idl
file complying with those extensions.
Over time, these restrictions will ideally go away.
To get a new IDL file from ROS2, follow this process:
cd ardupilot
source /opt/ros/humble/setup.bash
# Find the IDL file
find /opt/ros/$ROS_DISTRO -type f -wholename \*builtin_interfaces/msg/Time.idl
# Create the directory in the source tree if it doesn't exist similar to the one found in the ros directory
mkdir -p libraries/AP_DDS/Idl/builtin_interfaces/msg/
# Copy the IDL
cp /opt/ros/humble/share/builtin_interfaces/msg/Time.idl libraries/AP_DDS/Idl/builtin_interfaces/msg/
# Build the code again with the `--enable-dds` flag as described above
Development Requirements
Astyle is used to format the C++ code in AP_DDS. This is required for CI to pass the build. See Tools/CodeStyle/ardupilot-astyle.sh.
./Tools/CodeStyle/ardupilot-astyle.sh libraries/AP_DDS/*.h libraries/AP_DDS/*.cpp
Pre-commit is used for other things like formatting python and XML code. This will run the tools automatically when you commit. If there are changes, just add them back your staging index and commit again.
- Install pre-commit python package.
- Install ArduPilot's hooks in the root of the repo, then commit like normal
cd ardupilot
pre-commit install
git commit