ros_multimaster

The goal of this repo is to create a simple solution to dealing with time synchronization between multiple multimasters in ROS. The setup necessary will be provided in setup files and then to add a new machine to the network you should only need to add the IP and all the /etc/hosts will be updated.

The network setup is from: https://digital.csic.es/bitstream/10261/133333/1/ROS-systems.pdf

Setup server

Step 1. Start a network process

sudo python server/network.py

Step 2. Start the webserver

cd webserver/

export FLASK_APP=app

flask run

Setup client

Step 1. Run network setup

sudo python3 client/client_setup.py <SERVER-IP> wlan0 5006

Step 2. Start all clients and close the program after every client is connected to the server.

sudo python network/client.py <SERVER-IP>

Setup for a single ROS network (both hosts and clients)

Step 1. Install multimaster-fkie

sudo apt-get install ros-melodic-multimaster-fkie

or https://github.com/fkie/multimaster_fkie

Step 2. Put this in the ~/.bashrc file with the IP of that machines IP.

export ROS_MASTER_URI=http://<hostname or IP address>:11311

Setup NTP on host

Install NTP

sudo apt install ntp

Save ntp.conf in /etc/ntp.conf

sudo cp ntp.conf /etc/ntp.conf

Start the service

sudo service ntp start

Setup chrony on client

Install chrony

sudo apt install chrony

Edit the <host-ip> with the host ip then save this in /etc/chrony/chrony.conf

server <host-ip> minpoll 0 maxpoll 4 maxdelay .05
initstepslew 2 <host-ip>
keyfile /etc/chrony/chrony.keys
commandkey 1
driftfile /var/lib/chrony/chrony.drift
maxupdateskew 5
dumponexit
dumpdir /var/lib/chrony
pidfile /var/run/chronyd.pid
logchange 0.5
rtcfile /etc/chrony.rtc
rtconutc
rtcdevice /dev/rtc
sched_priority 1
local stratum 10
allow 127.0.0.1/8

Synchronize with the server

systemctl chrony stop
systemctl chrony start

For debugging

chronyc tracking

Starting the multimaster (on both host and clients)

Testing requires 4 terminals running on each machine.

Start roscore on every machine

roscore

Start a master discovery

rosrun master_discovery_fkie master_discovery _mcast_group:=224.0.0.1

Start a master sync

rosrun master_sync_fkie master_sync

Testing

Run publish_data.py or recieve_data.py on any machine.

python publish_data.py
python recieve_data.py