针对电容层析成像技术的逆问题中图像重构精度与速度的矛盾性,以12电极电容层析成像系统为对象,提出了一个改进型离线迭代在线重构(OIOR)算法.改进型OIOR算法是针对OIOR算法成像精度不高的问题加入了迭代滤波过程,既保证了成像速度,同时也提高了成像精度.以仿真电容值和实测电容值进行了图像重构的实验验证,从成像效果、相对误差、相关系数以及重构时间这4个方面对此算法进行了分析评估.仿真及实验结果表明:改进型OIOR算法通过迭代滤波100次即可在20 ms内有效提高传统OIOR算法重构图像的精度,使其相对误差降低约20%;与传统迭代法相比,在获得相同精度图像的条件下,其重构时间约为传统迭代算法的1/10.
In inverse problem of electrical capacitance tomography (ECT), the image reconstruction precision contradicts the rate. For a 12-electrode ECT system, improved offline iteration online reconstruction (OIOR)is put forward to meet the requirement of image reconstruction. Iterative filtering process joins the existing OIOR to improve the imaging precision and to simultaneously ensure the reconstruction rate. The simulated and measured capacitances are evaluated and analyzed for imaging results, relative error, correlation coefficient and the reconstruction period. The simulation and experiments show that the improved OIOR method is able to improve the precision of reconstructed image and reduce the relative error by 20% via 100 recursive filterings within 20 ms. The reconstruction period can be reduced to 10% of the traditional iterative method under the same image precision requirement.