This is a basic example for a package that can be submitted to the robots of the Real Robot Challenge.

It is a normal catkin package. The only special things are the following files which are used by the robot cluster system:

• goal.json: Contains the desired difficulty level and optionally a specific goal. In the given example, the goal is "commented out" by changing the key name. If no goal is given, a random one is sampled based on the specified difficulty level. Note that the difficulty level is always needed, also if a specific goal is given, as it is needed for computing the reward.
• run: Script that is executed when submitting the package to the robot. This can, for example, be a Python script or a symlink to a script somewhere else inside the repository. In the given example, it is a shell script running a Python script via rosrun. This approach would also work for C++ executables. When executed, the difficulty level and the goal pose of the object are passed as arguments.

This example uses purely Python but you could also add C++ code. In this case you need to add the corresponding build commands in CMakeLists.txt (and potentially specify dependencies in package.xml as for any catkin package.

It is important that the run script is executable as is. For this, you need to do two things:

1. Add a shebang line at the top of the file (e.g. #!/usr/bin/python3 when using Python or #!/bin/bash when using bash).
2. Mark the file as executable (e.g. with chmod a+x run).

When inside of run you want to call another script using rosrun (as it is done in this example), this other script needs to fulfil the same requirements.