A new capacitive rotary encoder based on analog synchronous demodulation

Rotary encoders, which are mainly used to feedback the angle of the robot arm to the robot controller system, are widely used in industrial and robotic applications. While optical and magnetic rotary encoders are dominant in the market, capacitive rotary encoders are also gaining interest for their simple design, ability to miniaturize and being absolute encoders insensitive to magnetic field variations. In this study, a new economical capacitive rotary encoder based on analog synchronous demodulation is developed. Analog synchronous demodulation technique is used for the first time in the literature as far as known to the authors for capacitive rotary encoders. It is chosen as it is quite robust, simple and economical. A compact mechanical body is developed by 3D printing. After packaging, the sensor is fixed to a motor for testing. The developed encoder shows 2880 pulse/rotation resolution and repeatable output under different temperature environments.