You might get some ideas from this "inverted pendulum":http://www.quanser.com/english/html/products/fs_product_challenge.asp?lang_code=english&pcat_code=exp-lin&prod_code=L2-invpen&tmpl=1 product. Check out the "pdf.":http://www.quanser.com/english/downloads/products/Linear/IP02_PIS_031108.pdf
These guys also did a good job and they documented their project.
