RMW Configuration

This guide details how to configure the RMW implementation for the first time if using the ROS Interface.

ROS 1 Interface & Create® 3

There is no need to configure the RMW on ROS 1. This is because the ROS 1 Interface uses rmw_fastrtps_cpp which is great at working with multi-device networks. We also use ros1_bridge on the LoCoBot's computer which allows the remote computer to see the ROS 2 topics/services/actions from the Create® 3.

ROS 2 Interface & Create® 3

Note

This guide assumes that you have run the ROS 2 Software Setup for both your LoCoBot and remote computers.

The ROS 2 Interface uses rmw_fastrtps_cpp as its RMW and the Fast-DDS Discovery Server.

Create® 3

Note

These modifications are done by Trossen Robotics and the user does not have to worry about modifying these unless they are setting up a robot themselves, or if they are dealing with a unique network setup.

The Create® 3 has the following modifications:

RMW_IMPLEMENTATION is set to rmw_fastrtps_cpp.
Fast DDS discovery server is enabled.
Address and port of Fast DDS discovery server are set to 192.168.186.3:11811.

You can find a list of all modifications the Create 3 Software Setup's ROS 2 Main Configuration.

LoCoBot Computer

Note

These modifications are done by Trossen Robotics and the user does not have to worry about modifying these unless they are setting up a robot themselves, or if they are dealing with a unique network setup.

The LoCoBot computer has the following modifications:

`RMW_IMPLEMENTATION` Environment Variable

The RMW_IMPLEMENTATION environment variable is set to rmw_fastrtps_cpp.

export RMW_IMPLEMENTATION=rmw_fastrtps_cpp

`ROS_DISCOVERY_SERVER` Environment Variable

The ROS_DISCOVERY_SERVER environment variable is set to 127.0.0.1:11811, the localhost address using port 11811.

export ROS_DISCOVERY_SERVER=127.0.0.1:11811

Fast-DDS Super Client XML Configuration File

All participants are configured to act as a Super Client via the XML configuration file, setting the UDP locator to address 127.0.0.1 and port 11811.

<?xml version="1.0" encoding="UTF-8" ?>
<dds>
    <profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
        <participant profile_name="super_client_profile" is_default_profile="true">
            <rtps>
                <builtin>
                    <discovery_config>
                        <discoveryProtocol>SUPER_CLIENT</discoveryProtocol>
                        <discoveryServersList>
                            <RemoteServer prefix="44.53.00.5f.45.50.52.4f.53.49.4d.41">
                                <metatrafficUnicastLocatorList>
                                    <locator>
                                        <udpv4>
                                            <address>127.0.0.1</address>
                                            <port>11811</port>
                                        </udpv4>
                                    </locator>
                                </metatrafficUnicastLocatorList>
                            </RemoteServer>
                        </discoveryServersList>
                    </discovery_config>
                </builtin>
            </rtps>
        </participant>
    </profiles>
</dds>

`FASTRTPS_DEFAULT_PROFILES_FILE` Environment Variable

The FASTRTPS_DEFAULT_PROFILES_FILE environment variable is set to the location of the Fast-DDS XML configuration file. By default, this is at ~/interbotix_ws/src/interbotix_ros_rovers/interbotix_ros_xslocobots/install/resources/super_client_configuration_file.xml.

export FASTRTPS_DEFAULT_PROFILES_FILE=~/interbotix_ws/src/interbotix_ros_rovers/interbotix_ros_xslocobots/install/resources/super_client_configuration_file.xml

IP Forwarding Enabled

IP forwarding is enabled by setting net.ipv4.ip_forward=1 in /etc/sysctl.conf. See this guide on IP forwarding from OpenVPN for more information.

# Uncomment the next line to enable packet forwarding for IPv4
net.ipv4.ip_forward=1

Fast-DDS Discovery Server Service

Fast-DDS Discovery Server running as service fastdds_disc_server.service at startup.

#!/bin/bash
source /opt/ros/${ROS_DISTRO}/setup.bash
fastdds discovery -i 0 &
exit 0

The status of this service can be checked with the command:

$ systemctl status fastdds_disc_server.service

● fastdds_disc_server.service - FastDDS discovery server
    Loaded: loaded (/lib/systemd/system/fastdds_disc_server.service; enabled; vendor preset: enabled)
    Active: active (running)
    Process: 1349 ExecStart=/bin/bash -e /home/locobot/interbotix_ws/src/interbotix_ros_rovers/interbotix_ros_xslocobots/install/resources/service/fastdds_disc_server.sh (code=exited, status=0/SUCCESS)
Main PID: 1393 (bash)
    Tasks: 10 (limit: 9105)
    Memory: 13.8M
    CGroup: /system.slice/fastdds_disc_server.service
            ├─1393 /bin/bash -e /home/locobot/interbotix_ws/src/interbotix_ros_rovers/interbotix_ros_xslocobots/install/resources/service/fastdds_disc_server.sh
            ├─1395 python3 /opt/ros/galactic/bin/../tools/fastdds/fastdds.py discovery -i 0
            └─1397 /opt/ros/galactic/bin/fast-discovery-server -i 0

                locobot systemd[1]: Starting FastDDS discovery server...
                locobot systemd[1]: Started FastDDS discovery server.
                locobot bash[1397]: ### Server is running ###
                locobot bash[1397]:   Participant Type:   SERVER
                locobot bash[1397]:   Server ID:          0
                locobot bash[1397]:   Server GUID prefix: 44.53.00.5f.45.50.52.4f.53.49.4d.41
                locobot bash[1397]:   Server Addresses:   UDPv4:[0.0.0.0]:11811

Remote Computer

The remote computer has the following modifications, done by the remote installation script:

`RMW_IMPLEMENTATION` Environment Variable

The RMW_IMPLEMENTATION environment variable is set to rmw_fastrtps_cpp.

export RMW_IMPLEMENTATION=rmw_fastrtps_cpp

`ROS_DISCOVERY_SERVER` Environment Variable

The ROS_DISCOVERY_SERVER environment variable is set to the LoCoBot's IP address and port 11811.

export ROS_DISCOVERY_SERVER=${LOCOBOT_IP}:11811

Fast-DDS Super Client XML Configuration File

All participants are configured to act as a Super Client via the XML configuration file, setting the UDP locator to the address of the LoCoBot's LoCoBot's wireless network interface's IP address, ${LOCOBOT_IP}, and port 11811.

<?xml version="1.0" encoding="UTF-8" ?>
<dds>
    <profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
        <participant profile_name="super_client_profile" is_default_profile="true">
            <rtps>
                <builtin>
                    <discovery_config>
                        <discoveryProtocol>SUPER_CLIENT</discoveryProtocol>
                        <discoveryServersList>
                            <RemoteServer prefix="44.53.00.5f.45.50.52.4f.53.49.4d.41">
                                <metatrafficUnicastLocatorList>
                                    <locator>
                                        <udpv4>
                                            <address>${LOCOBOT_IP}</address>
                                            <port>11811</port>
                                        </udpv4>
                                    </locator>
                                </metatrafficUnicastLocatorList>
                            </RemoteServer>
                        </discoveryServersList>
                    </discovery_config>
                </builtin>
            </rtps>
        </participant>
    </profiles>
</dds>

`FASTRTPS_DEFAULT_PROFILES_FILE` Environment Variable

The FASTRTPS_DEFAULT_PROFILES_FILE environment variable is set to the location of the Fast-DDS XML configuration file. By default, this is ~/interbotix_ws/src/interbotix_ros_rovers/interbotix_ros_xslocobots/install/resources/super_client_configuration_file.xml.

export FASTRTPS_DEFAULT_PROFILES_FILE=~/interbotix_ws/src/interbotix_ros_rovers/interbotix_ros_xslocobots/install/resources/super_client_configuration_file.xml

IP Routing Service

A route is added to IP subnet 192.168.186.0/24 via the LoCoBot's wireless network interface's IP address via a service running on startup.

ip route add 192.168.186.0/24 via ${LOCOBOT_IP}

The status of this service can be checked with the command:

$ systemctl status ip_routing.service

● ip_routing.service - Enable LoCoBot IP routing for 192.168.186.0/24
        Loaded: loaded (/lib/systemd/system/ip_routing.service; enabled; vendor preset: enabled)
        Active: inactive (dead) since
    Process: 8940 ExecStart=/home/interbotix/interbotix_ws/src/interbotix_ros_rovers/interbotix_ros_xslocobots/install/resources/service/ip_routing.sh (code=exited, status=0/SUCCESS)
    Main PID: 8940 (code=exited, status=0/SUCCESS)

interbotix systemd[1]: Started Enable LoCoBot IP routing for 192.168.186.0/24.
interbotix systemd[1]: ip_routing.service: Succeeded.

The IP route can be checked with the command:

$ ip route list
192.168.186.0/24 via ${LOCOBOT_IP} dev wlp0s20f3

Here, we can see that the route has been added via the remote computer's wireless network interface, wlp0s20f3.

RMW Configuration

ROS 1 Interface & Create® 3

ROS 2 Interface & Create® 3

Create® 3

LoCoBot Computer

RMW_IMPLEMENTATION Environment Variable

ROS_DISCOVERY_SERVER Environment Variable

Fast-DDS Super Client XML Configuration File

FASTRTPS_DEFAULT_PROFILES_FILE Environment Variable

IP Forwarding Enabled

Fast-DDS Discovery Server Service

Remote Computer

RMW_IMPLEMENTATION Environment Variable

ROS_DISCOVERY_SERVER Environment Variable

Fast-DDS Super Client XML Configuration File

FASTRTPS_DEFAULT_PROFILES_FILE Environment Variable

IP Routing Service

`RMW_IMPLEMENTATION` Environment Variable

`ROS_DISCOVERY_SERVER` Environment Variable

`FASTRTPS_DEFAULT_PROFILES_FILE` Environment Variable

`RMW_IMPLEMENTATION` Environment Variable

`ROS_DISCOVERY_SERVER` Environment Variable

`FASTRTPS_DEFAULT_PROFILES_FILE` Environment Variable