There are many useful websites and videos with great ideas to get started or even to create a pretty sophisticated Rescue robot.
David’s Robotics Portal
Here you will find many useful ideas and videos for designing and programming Lego Rescue robots. You should also check his blog with information for using Lego’s new Spike Prime for Rescue. This is out of Western Australia so there is also information about RoboCup Junior competitions in WA.
A PID Controller for Lego Mindstorms Robots
This link will take you to a fairly comprehensive description of the principles behind the PID algorithm. It is written with NXT-G in mind, but the principles are still the same.