An electric system utilizes dynamic impedance changes in windings of an electric motor to measure/monitor mechanical position. The method employs a bridge amplifier to measure voltage at a center node or windings against a voltage derived from a reference network. When a winding of the motor is driven,...http://www.google.ca/patents/US6703805?utm_source=gb-gplus-sharePatent US6703805 - System for measuring the position of an electric motor
