The first step to starting any project is to clearly define what the goals are and what the primary deliverable is.
 
Goal:  Apply theoretical knowledge of OS design and implementation
To me this is the ultimate goal of Rex OS.  The reason I believe this is such an important goal is because it is without a doubt the most practical way to demonstrate a solid understanding of the topics surrounding OS design and implementation.

In the past I’ve found that merely reading and attending lectures is not enough to fully understand any topic let alone a topic as complex as operating systems.  As a result of implementing Rex OS I hope to solidify my understanding of operating systems and demonstrate a practical understanding that will serve as a foundation for future, more experimental, projects.
 
Deliverable:  Build a hard real-time operating system for embedded devices
The primary deliverable for Rex OS is a fully functioning operating system.  Rex OS must be a hard real-time operating system due to the fact that it will be used in a system (RC Rex) that will interact with the physical world with potentially catastrophic failure scenarios and strict requirements on timing.  Furthermore, due to the nature of RC Rex the operating system must be capable of running smoothly in an embedded environment that has few resources available in terms of memory, processing ability, and power.
 
Personally I am very excited about Rex OS and RC Rex.  Both projects are challenging, but when they will be extremely rewarding and allow for an immense amount of learning in an area that I find incredibly intriguing.