Dynamic model of robot manipulator

Hi there,

I'm working on a 6-DOF serial robotic manipulator, and needs a dynamic model of it. I have computed the torque equations based on an iterativ model from the book on robotics by Craig, but the equations are huge. The text document of the equations in plain text is 4 MB, and impossible to work with.

Are they normally that huge for 6-DOF serial manipulators, and are there ways to perhaps approximate them, but keeping them nonlinear for control?

Thanks