In order to achieve the target of early internal defect detection of stand tree and get rid of limitations of other detection technology in the actual operation of stand tree flaw detection, this paper proposes to apply the electrical impedance tomography to the internal defects of stand tree.The research is proposed for the first time domestically.Firstly the signal generation module based on AD9850 and VCCS (Voltage-controlled Current Source) were used to generate constant current excitation signals and input to the surface of stand tree following a certain motivational pattern.Then the independent boundary voltage values were collected by the weak signal acquisition module based on the double-stage amplifier and the AD637.The results were transferred to the host computer to achieve resistance imaging by inverse back projection algorithm.The proposed system was applied in the actual tree for flaw detection.The results show that the system can effectively, rapidly and accurately reflect early decay discoloration on the cross section of stand tree.%为实现活立木内部缺陷的早期检测,同时摆脱立木腐朽检测中其他检测手段在实际操作中的局限性,提出将电阻断层成像技术应用到活立木内部缺陷的检测当中.该系统首先利用基于AD9850的激励信号发生器和压控电流源产生恒流激励信号,并遵循一定的激励方式循环输入到立木表面,然后利用基于双级程控放大器和AD637等微弱信号采集模块收集独立的边界电压值,最后输入到上位机通过等位线反投影算法实现电阻抗成像.实验部分将本系统应用在实际立木腐朽探伤检测中,结果表明本系统能够有效快速地反映出立木横截面的早期腐朽变色情况.
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