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传统PID控制方法在检测激光诱导击穿光谱过程中,受到激光能量波动、样品不均匀性的干扰,检测结果不稳定。因此,提出激光诱导击穿光谱的自动化PID控制改进方法,建立闭环负反馈式激光光谱检测装置,对比分析激光输出功率同预设值,同时将输出功率反馈至激光电源,利用自动化PID控制方法,根据功率偏差值得到相应的控制量,自动调整氙灯供电电压,从而将脉冲激光功率控制在预设值附近。通过优化PID参数,使激光功率波动稳定在±2.5%以内,实现长期稳定测量,提高了激光诱导击穿光谱检测的可靠性。采用Visual C++编写控制方法的软件,并给出自动化PID控制方法的主程序和子程序流程图。实验结果说明,所提方法能够实现激光诱导击穿光谱的自主控制,控制效率高、鲁棒性强。
In the process of detecting laser-induced breakdown spectroscopy, the traditional PID control method is disturbed by laser energy fluctuation and sample inhomogeneity, and the test result is unstable. Therefore, an improved PID control method based on laser-induced breakdown spectroscopy is proposed, and a closed-loop negative feedback laser detection device is established. The laser output power is compared with the preset value and the output power is fed back to the laser power supply. According to the power deviation value to get the corresponding control volume, automatically adjust the xenon lamp power supply voltage, so that the pulse laser power control in the vicinity of the preset value. By optimizing the PID parameters, the laser power fluctuation can be stabilized within ± 2.5% to achieve long-term stable measurement and improve the reliability of laser induced breakdown spectroscopy. Using Visual C ++ to write the software of control method, and give the main program and subroutine flow chart of automatic PID control method. The experimental results show that the proposed method can achieve the autonomous control of laser-induced breakdown spectroscopy with high control efficiency and robustness.