Implementation of Fuzzy Self-tuning Proportional Integral Derivative Controller on Sample-tube Spin Control System in Nuclear Magnetic Resonance Spectrometer
在核磁共振(nMr)实验中,样品旋转能够有效消除Xy方向磁场的部分不均匀性,从而提高信号分辨率。在商用nMr谱仪中,一般采用PId算法进行待测样品的旋转控制。由于被控对象具有一定的非线性,存在着调节时间较长,稳定后存在误差等缺点。针对该现象,在VArIAn 500 MHz波谱仪气路系统的基础上,设计一套新的控制电路,在控制方法上引入了模糊PId控制,经过多次实验调试、优化处理,定制了适用于nMr谱仪气控系统的模糊参数隶属函数和模糊规则,设计出一种模糊自适应PId控制算法。结果表明,本系统较原系统稳定时间缩短了约30 S。在相同的实验环境下采样,本系统得到半高宽均值为1.27 Hz,信噪比为2293,优于VArIAn气控系统采样所得的结果,增强了旋转控制的鲁棒性,加快了响应速度和稳定速度,具有较高的应用价值。In commercial nuclear magnetic resonance(NMR) spectrometer,a PID controller is generally used to regulate the rotation of samples.There are some faults such as long adjustment time,steady-state error because of the nonlinear character of the object.To improve system performance,a new pneumatic controller system was proposed by using self-tuning fuzzy proportional-integral-derivative(PID) controller to replace the original pneumatic system based on PID.The adjustment time of proposed controller is about 30 s shorter than that of Varian.The result of the experiment under the same environment shows that the half-height width after applying the proposed controller is 1.272 better than 1.396 of Varian and S/N is 2293.114 better than 2245.48 of Varian.The experiment result shows that the proposed controller is robust,quicker response and has great value for application and research.国家科技支撑计划(No.2006BAK03A22);国家博士后基金(No.20090460750)资
