A Capacitive Rotary Encoder Based on Quadrature Modulation and Demodulation

作者：Zheng Dezhi^*; Zhang Shaobo; Wang Shuai; Hu Chun; Zhao Xiaomeng

来源：IEEE Transactions on Instrumentation and Measurement, 2015, 64(1): 143-153.

DOI：10.1109/TIM.2014.2328456

• Angular velocity
• capacitance measurement
• encoding
• phase modulation
• quadrature amplitude modulation
• rotating machine measurements

This paper presents a capacitive rotary encoder for both angular position and angular speed measurements. The encoder is mainly composed of three parts: 1) the transmitting segments; 2) a pair of reflecting electrodes; and 3) a pair of receiving electrodes. The transmitting segments together with four mutual quadrature carrier voltages provide a modulated electric field. The reflecting electrodes, which are patterned sinusoidally can encode the angular position to a phase/frequency modulated signal based on quadrature modulation. The modulated signal is then digitally decoded to the angular position in a field programmable gate array processor based on the quadrature demodulation and the coordinate rotational digital computer algorithm. Through a universal serial bus, the digital angular position is transmitted to a computer for further analysis in National Instruments' LabVIEW software. A prototype of the capacitive encoder shows that its precision is better than 0.006 degrees and the resolution is 0.002 degrees. The dynamic nonlinearity is evaluated at +/- 0.4 degrees when the rotor is rotating at 1000 r/min.

• 出版日期2015-1
• 单位北京航空航天大学