DIY Arduino Servo Motor : Control DC Motor Position

I needed position control of a servo motor capable of generating at least 120kg-cm of torque. A commercial servo motor would have probably cost me hundreds of dollars, so I decided to make one out of a geared DC motor and a potentiometer feedback system. Full description and source code available on my blog: http://bayesianadventures.wordpress.com/2014/01/04/diy-servo-motor-cheap-and-with-plenty-muscle/