Rancang Bangun Tomografi Kapasitansi Listrik dengan Sensor Tersegmentasi dan Berperisai untuk Deteksi Benda Dalam Pipa

Abstract

Tomography is a nondestructive and noninvasive cross-section imaging technique which is very useful in industrial, healthcare and security application. Observation can be performed by observing objects interaction to external excitation signal. Object is scanned by measuring capacitance value through various part of the object. The gathered information is used to reconstruct the internal structure of the object. In this final project, an electrical capacitance tomography system is designed using segmented and shielded sensors. Electrical capacitance tomography harness the capacitance information between different measurement section caused by the different permittivity constant exhibited by different materials to reconstruct internal cross-section image of the object. The sensor configuration is controlled using analog multipexer made by an array of HEF4066B CMOS switches. Capacitance measurement is done using charge measurement method. Measured signal is conditioned using high-pass filter, amplifier, precision rectifier and averaging filter then digitized using ADC of ATmega8A microconroller. Image reconstruction is done using linear backprojection algorithm. From the test result, the electrical capacitance tomography system can detect object location and differentiate object composition. The implementation of segmented sensor results in an increase of sensor sensitivity by factor of 2,76 compared to single sensor with sensitivity value of 0,515 V/pF. The implementation of shielded sensor results in the decrease of external disturbace effect on sensor measurement. The result of this final project can be implemented in industrial application for pipe content monitiring where minimum regulation requirement is desired.