Implementation and Evaluation of a Prototype Capacitive-Type Rotary Encoder

Angular displacement measuring encoder is one of the most important measuring tools in the automated systems, industries and machine tools. In many of manufacturing and production processes, rotary encoders are used as reliable tools for precise positioning. In this study, a new capacitive-type rotary encoder with un-tethered rotor is designed. The main components are made of printed circuit films. Hence, the encoder can be set up in thin inter spaces. The encoder consists of a receiving stator and a transmitter rotor, respectively containing four-phase and two-phase electrodes. In order to designs an un-tethered rotor; the encoder employs a unique approach. Electrical power is supplied to the transmitter rotor by electrostatic induction without any physical contact. This untethered rotor can facilitate sensitive applications that a mechanical disturbance caused by an electric wire can be a problem. In this study the encoder was built and its performance was evaluated. The result of experimental evaluation shows that the encoder has max ±0.09 degree error.