Auto Swarm Bridge

A ROS package for multi-robot message transport based on zmqpp

This package is a separate package version of the swarm_bridage used in CREPES3

Feature

• HEADER Only, easy to use
• High Performance, capable to transfer odom message higher than 1000Hz with out fluctuation, tested on Ubuntu 18.04 / 20.04
• Automatically get self ip, and Broadcast self id and self ip using UDP.
• Automatically Connect with others Under Same Network, using TCP to transport messages in need
• ROS-like publish/subscribe API
• Capable of simulating Network Delay, by setting simulation to true and giving virtual_network_delay manually in the launch file

Usage

Install zmqpp first

sudo apt install libzmqpp-dev

Add this package into your workspace, and compile it, a simple demo could be done by roslaunch:

roslaunch swarm_bridge test_swarm_bridge.launch

or by rosmon:

mon launch swarm_bridge test_swarm_bridge.launch

See example for detailed usage

// Initialization
SwarmBridge::Ptr swarm_bridge(new SwarmBridge(nh));

// Register subscriber
swarm_bridge->subscribe<${YOUR_MSG_TYPE}>("${YOUR_TOPIC_NAME}", [&](${YOUR_MSG_TYPE} msg){${YOUR_CODE});

// Publish
swarm_bridge->publish<${YOUR_MSG_TYPE}>("${YOUR_TOPIC_NAME}", msg);

Change ${YOUR_MSG_TYPE} into the message type you want to transfer, like nav_msgs::Odometry or visualization_msgs::Marker. Change ${YOUR_TOPIC_NAME} into the name of the topic, just like ros. Implement your customized code to substitute ${YOUR_CODE}

Sometimes there may meet situations that cannot automatically get ip in proper network. E.g., using both wireless network and wired network, and want to transfer message under wireless network. The priority of wired network usually higher than the wireless network, and the program will automatic get information under uninterested network. To deal with this situation, please modify the param in launch file of net_mode to manual and set self_ip and broadcast_ip under proper network.

Known issues

If you are using this project as a inner class in your work, and have multi ros callback queues, there might have a little problem in

template <typename T>
void SwarmBridge::publish(const std::string &topic_name, const T &msg)
{
    ...
    if (this->simulation_)
    {
        auto start = std::chrono::steady_clock::now();
        while (std::chrono::duration_cast<std::chrono::microseconds>(std::chrono::steady_clock::now() - start).count() < this->virtual_network_delay_)
        {
        ros::spinOnce();
        }
    }
    ...
}

Set the simulation to false might help.

Future work

• separate different groups for broadcast