I am currently in 3rd year in Mechanical Engineering studies at UMIST in Manchester England. My project for this year is to design a miniaturised CNC lathe, approx 100mm x 100mm x 100mm. I will be using a DC brushless motor to turn the spindle and a combination of actuators to move the tool. I will be controlling them using PID algorithms, but currently am having problems deriving transfer functions, as i have little experience with the frequency domain. Does anybody know, or know how to derive, transfer functions for DC brushless motors, piezoelectric actuators, and other such actuators that may be suitable for such a miniaturised machine?
Any help or correspondence is greatly appreciated.

Cheers
Paul Nicholson
Dept of Mechanical, Aerospace and Manufacturing Engineering
UMIST
Manchester
England

 

Hey Paul - we used Automatic Control Systems by Hollinger and Harrison to learn about Transfer functions and how to derive them for different systems mathematically.

But I would suspect that it is not the motor you would need but the system, which the motor forms a part of. I found out the hard way that the sum of the parts has no relation on the end result!!

Cheers from: Jeremy Pollard, CET The Crazy Canuckian!
Integration and Automation Training, Consulting, and Software
http://www.tsuonline.com