Differential Drive Model with MATLAB/SIMULINK

[jlipstate]

Hello,

I am making a model (Virtual robot) in simulink/matlab. My approach thus far has been to model the robot as a differential drive (Two wheels with a massless rod connecting them). I've been working on deriving a combined Equation of Motion for the system, but am not really getting very far with that. The idea I am trying to implement is using state-space x = [theta dot, omega dot] and using torques on each wheel to control the system. Does anyone know where I can find information related to this? Or even better, have the combined EoM of a differential drive?

Thanks!