Hardware Design of Large-scale Sensor-based Electrical Capacitance Tomography Systems

Large-scale sensor-based Electrical Capacitance Tomography systems have a bright industrial application prospect. However, in terms of the hardware design of capacitance measuring circuits of the systems, a particular difficulty is to eliminate strong stray capacitance measuring interference produced by overlong single-shield coaxial cables and single analog switches. Therefore, in this paper different drive cable technologies are analyzed and complete drive cable technology is applied to the measuring circuits in order to eliminate coaxial cable stray capacitance interference. Furthermore, a double-T-switch connection is utilized for eliminating stray capacitance interference caused by using single switch arrangements. Also, a double electrode excitation strategy is implemented to suppress the noise generated in large-scale sensors and to enhance the Signal-to-Noise Ratio (SNR) of measuring circuits. Experimental results show that capacitance measuring circuits using the proposed anti-interference hardware have good stray capacitance suppression properties, a high SNR (57 dB) and good stability.