1. Key Lab of Measurement Technology and Instrumentation of Hebei Province, Yanshan University, Qinhuangdao, Hebei 066004, China
2. Institute of Defense Science and Technology,Yanshan University, Qinhuangdao, Hebei 066004, China
Abstract：Using a conventional single dielectric medium as empty or full field often leads to the low measurement accuracy when the planar array electrode capacitance imaging technology is applied to nondestructive testing of defects, because electrodes are arranged in the same plane. A method of setting the relative empty/full field using air and tested material as dielectric is proposed. The capacitance value of empty/full field is adjustable and non-unique by changing the spatial position and size of the two kinds of medium, respectively. The working principle of the planar array capacitance sensor is described and the sensitivity matrix is obtained by means of finite element simulation for measure field made up of heat insulating material and epoxy resin. Experimental study on capacitance imaging is conducted for empty and full field setting method. The results show that the imaging quality can be improved, the plane position information of defects in the object is given, and the validity of the method is verified.
［1］Madhusudana Rao S, Zhu Kewu, Wang Chi Hwa, et al. Electrical Capacitance Tomography Measurements on the Pneumatic Conveying of Solids［J］. Industrial & Engineering Chemistry Research,2001,40(20):4216-4226.
［2］Weber J M, Mei J S. Bubbling fluidized bed characterization using Electrical Capacitance Volume Tomography (ECVT)［J］.Powder Technology,2013,242(4):40-50.
［3］Huang Z, Wang B, Li H. Application of electrical capacitance tomography to the void fraction measurement of two-phase flow［J］. IEEE Transactions on Instrumentation & Measurement,2003,52(1):7-12.
［4］李雄兵,杨岳,梁运涛. 含孔隙碳纤维复合材料对超声波相速度的影响［J］. 计量学报,2008,29(4):378-381.
［5］薛倩,马敏,王化祥,等.用于复合材料缺陷可视化检测的l1正则化算法［J］.自动化仪表,2014,35(10):1-4.
［6］郝魁红,范文茹,马敏,等. 平面式电容传感器阵列测量复合材料技术研究［J］. 传感器与微系统,2014,33(2):35-38.
［7］Hu X, Yang W. Planar capacitive sensors-Designs and applications［J］.Sensor Review,2010,30(1):24-39.
［8］Li X B, Larson S D, Zyuzin A S, et al. Design principles for multichannel fringing electric field sensors［J］.IEEE Sensors Journal,2006,6(2):434-440.
［9］Sun J, Ren Z, Yang W. 3D imaging with single-plane electrical capacitance tomography sensor［J］. Electronics Letters,2015,51(3):222-224.
［10］范作宪,董恩生,曹河,等. 同面多电极传感器敏感场计算方法研究［J］. 计算机测量与控制,2013,21(4):1109-1111.
［11］Ye J, Mao M, Wang H, et al. Image Reconstruction for ECT Based on Extended Sensitivity Matrix［J］.IEEE Sensors Journal,2016,16(8):2466-2476.
［12］Marashdeh Q, Warsito W, Fan L S, et al. A nonlinear image reconstruction technique for ECT using a combined neural network approach［J］.Measurement Science & Technology,2006,17(8):2097-2103.
［13］马敏,王伯波,闫超奇,等.基于旋转电极的电容层析成像技术图像融合算法［J］. 计量学报,2018,39 (1): 43-46.
［14］马敏,郭琪,闫超奇,等.基于l2,p-范数的ECT图像重建算法［J］. 计量学报,2017,38 (5): 611-615.
［15］Ye Z, Banasiak R, Soleimani M. Planar array 3D electrical capacitance tomography［J］. Insight-Non-Destructive Testing and Condition Monitoring,2013,55(12):675-680.
2018, Vol. 39 
