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为提高电阻抗成像数据采集系统的信噪比并且简化硬件电路设计,提出了一种基于Walsh函数的最优电流激励模式。利用Walsh电流对敏感场域进行激励,测量其电压响应,借助统计线性回归求解阻抗矩阵并将最优激励模式下的电压响应表示为Walsh电压响应的线性组合。结合正则化Gauss-Newton法重建阻抗图像。仿真结果表明,Walsh函数最优电流激励模式可以改善硬件系统的抗噪声能力,并且保证整个敏感场域内电流密度分布的均匀性。结合最优电流激励模式进行图像重建,提高了重建算法的收敛速度及重建图像的质量。
In order to improve the SNR of the electrical impedance imaging data acquisition system and simplify the design of the hardware circuit, an optimal current excitation mode based on Walsh function is proposed. The Walsh current is used to excite the sensitive field to measure the voltage response. Statistical linear regression is used to solve the impedance matrix and the voltage response in the optimal excitation mode is expressed as a linear combination of the Walsh voltage responses. Reconstruction of impedance image with regularized Gauss-Newton method. The simulation results show that the optimal current excitation mode of Walsh function can improve the anti-noise ability of the hardware system and ensure the uniformity of the current density distribution in the entire sensitive field. Combining the optimal current excitation mode for image reconstruction, the convergence speed of reconstructed algorithm and the quality of reconstructed image are improved.