A micro-motor position controller utilizes a ratiometric position sensor that operates independent of any reference voltage sources. A first capacitor and a second capacitor in a micro-motor are connected in series and form one section of a capacitive bridge. The other section of the bridge is ground....http://www.google.com.au/patents/US6469465?utm_source=gb-gplus-sharePatent US6469465 - Precision micro-motor position controller
