learning collision detection

I'm currently debugging mySimulation.c. While all of you know how this process can be long, I want here to talk about one current human error:
The goal of mySimulation.c functions and data is to simulate the motor and sensor behavior (when project is compiled for a target=PC-Physical). In this file, like in all file of the project, the task main() is dedicated to debug and validation of mySimulation.c functions and structures.
However, I was eager to see the first result of Robot Simulation, and I progressively turned the task main() of mySimulation.c into a small robot program in itself. So I added complexity where I needed simplest debug functionalities.
I understood my error when I realized that the bugs I tracked had too many origins instead of coming only from the simulation functions. In a development process, this is generally a bad sign when you begin to fix and patch your project everywhere.
I took sometimes to get a clear picture of all related project files, and to focus only on simulation functions. I should draw a (sort of) UML class diagram and add it to the documentation.
I reshaped and renamed some functions, and I currently learn some basics about collision detection (where I found main bugs).

Stay tuned ;-)