This is repository contains a ros package called "control_toy". This consists of a simulator that is similar to what was shown. Your job is to design a control algorithm for this simulator.
In addition to ROS, this simulation depends on pygame. to install pygame on ubuntu you have two options. Either run:
sudo apt install python-pygame
or
pip install pygame
To run the simulator add the package to your catkin workspace. Build the catkin workspace then run:
rosrun control_toy simulator.py
The simulator publishes the following data in std_msgs/Float64 format:
/simulator/depth
/simulator/setpoint
The simulator subscribes to the following topic (also of std_msgs/Float64 type).
/simulator/thruster
Publishing to this topic will allow you to control the vertical thruster on the yellow box.