MDRS-SSAM

This is the software github repo for the Nexus Aurora MDRS-SSAM project. It is a ROS+Gazebo workspace so you will need to install ROS and Gazebo. Follow the instructions here: http://wiki.ros.org/noetic/Installation/Ubuntu (currently we are using the noetic version of ROS but we are open to new suggestions)

For ROS tutorial it is advised that you follow the official ones from the ROS website: http://wiki.ros.org/ROS/Tutorials

Setup

To install ROS from scratch, run:

./install_ros.sh

This will install either ROS melodic or noetic, depending on your ubuntu version.

To build your project for the first time, run:

./build.sh

This will first install all missing required packages that the project depends on using rosdep, then will call catkin_make. Subsequently, you can just call catkin_make to build your project if no new required packages are added to the project. To add a new dependency, list it inside the package manifest using one of the tags. See http://wiki.ros.org/Manifest for more info.

Deploying code on remote hardware

To build your code on a remote machine, follow these steps:

1. Run:

./deploy.py -d <username>@<address>:<port> --save <machine_name>

This step is not mandatory, but it's useful to not have to type the address every time. The port is only necessary if it's different from the default ssh port (22). If this is the first time running the save command, a file named deploy_config.yaml will be created and your machine will be added and also set as the default. Subsequent calls to deploy.py won't need to mention any destination or machine.

1. If ROS is not installed on the machine, run:

./deploy.py --install

This will install the appropriate version of ROS as well as copy your code and build it.

1. Whenever you make changes and wish to rebuild, simply run:

./deploy.py

(Optional)

• To deploy to a destination that was not previously saved, run:

./deploy.py -d <username>@<address>:<port>

• To deploy to a machine that was saved but is not the default, run:

./deploy.py -m <machine_name>

Launching code on remote hardware

Install Husarnet and join VPN

For now we're using Husarnet as a VPN solution to connect to our remote hardware. To install and join the network, run the following commands:

curl https://install.husarnet.com/install.sh | sudo bash
sudo systemctl restart husarnet
sudo husarnet join <serveraddress> <clientname>

Contact one of the project members to send you the server address.

⚠️ Husarnet automatically changes your machine's hostname. As a result, you won't be able to launch a local ROS core. Temp solution: add the following lines to your ~/.bashrc file

if [[ -z "${ROS_REMOTE}" ]];
then
export ROS_HOSTNAME=localhost
fi

Launching the project

Use the launch.py script to run a launch file on a remote machine:

./launch.py [-d <username>@<address>:<sshport> | -m machine] <package> <launchfile> <launchargs...>

This command uses the same deploy_config.yaml file as the deploy script, so if you set that up you can omit the -d or -m parameters and just use the default machine. Optionally you can use the -t and -l parameters to launch a local terminal or launch file respectively, either one connected to the remote ROS master.

Presuming you're using the default machine defined in deploy_config.yaml, your launch command would look like this

./launch.py <remotepackage> <remotelaunchfile> <remotelaunchargs...> -t -l <localpackage> <locallaunchfile> <locallaunchargs...>

Packages

The project right now contains 4 packages:

• ssam_core
• ssam_control
• ssam_navigation
• ssam_simulation

Note: Since all packages are common inside ROS along with the ones externally provided, it is recommended any newly created packages you create to have the prefix ssam_.

After downloading the project, since this is a ROS catkin workspace, you should run "source devel/setup.bash" to get everything indexed properly in your terminal. Note that you will need to do this for every new terminal you open. I also suggest you use Terminator or some other terminal which allow terminal splitting as you will be opening a lot of different terminals while working with ROS.

SSAM Core

This project contains the robot URDF model, some useful xacro parameters and macros, as well as the main launch file for the robot functionality. This launch file is the one to be used when launching the project on the actual hardware. To start it, run "roslaunch ssam_core scout_startup"

SSAM Control

This package will contain all needed functionality to control the robot. Nodes:

• test_control_node : moves the robot forward for 2 seconds, then backwards for 2 seconds. This node only publishes on the (/cmd_vel) topic. You can start it with "rosrun ssam_control test_control_node"
• test_control_node2: This subscribes to the /odom topic to get info about the robot's position. If the robot's x coordinate is smaller than 2 it will tell the robot to move forward. If the x coordinate is greater than 5 it will tell the robot to move forward (using the /cmd_vel topic). You can start it with "rosrun ssam_control test_control_node2"
• scout_control: Runs the robot's hardware interface which will forward instructions from various controllers (right now only diff_drive_controller) to the actual hardware. This node does not run in simulation mode

SSAM Navigation

Mainly contains configuration files for a move_base node which takes in sensor data and a goal command and outputs cmd_vel commands to the diff_drive_controller. The launch file also launches a stereo_image_proc node (not currently used outside simulation) and a fake_localization node to complete the tf_tree when running on the actual hardware. This node will be removed.

SSAM Simulation

This package contains the gazebo world (/worlds), the robot model (/models/scout) and the launch file (/launch). To start it run "roslaunch ssam_simulation scout_startup.launch".

You should see gazebo startup, as well as rviz. You can use rviz to visualize various info about the robot, as well as issue goal commands for move_base. Optionally you can add the argument rviz_ns:=<robot_ns> if you wish to view info about a specific scout (default is scout1). If you wish to turn off rviz, pass rviz_ns:=none.

Multiple Scouts

To launch multiple scouts, use the argument scout_count:= to set how many scouts you want to spawn (they will be spawn 1 meter apart on the Y axis).

Note: Right now the scout uses world position and rotation provided by gazebo to navigate. This will be changed in the future. It also uses a laser for scanning purposes. This will also be changed.

If you start the simulation and a control node you should see the robot moving forward and backwards in the gazebo simulation. If you use multiple scouts in the simulation you need to use the _scout_name=<string_value> to tell the node which scout to control. For example "rosrun ssam_control test_control_node2 _scout_name:=scout3" will make the 3rd scout from the simulation to move forward and backwards. You can spawn multiple test_control_nodes to control multiple scouts.