原子力显微镜的分数阶PID控制设计

Design of fractional PID control for atomic force microscope

原子力显微镜(AFM)是测量材料物体表面形貌的重要工具。为了实现AFM的高速扫描成像,设计一种基于分数阶前馈-反馈PID控制算法的AFM扫描成像控制器。将分数阶迭代学习控制(FOILC)用于前馈回路,在跟踪过程中对当前周期的误差信息进行学习,实现输出沿迭代轴的快速收敛;在反馈回路中采用分数阶比例积分(FOPI)控制增加高速成像时的精度。轨迹跟踪仿真和实验成像结果表明,该算法能有效提高AFM成像速度和改善系统非线性的影响,在扫描频率为25 Hz时,控制精度达到10-5量级,AFM成像质量得到显著提高。

Atomic force microscope(AFM) is an important tool for measuring the surface morphology of material objects. In order to realize the high-speed scanning imaging of AFM, an AFM scanning imaging controller based on a Fractional Feedforward-Feedback PID control algorithm is designed. Use fractional-order iterative learning control(FOILC) in the feedforward loop to learn the error information of the current period in the tracking process to achieve rapid output convergence along the iterative axis;use fractional-order proportional integral(FOPI) control in the feedback loop Increase the accuracy of high-speed imaging. The trajectory tracking simulation and experimental imaging results show that the algorithm can effectively increase the AFM imaging speed and improve the system’s nonlinear impact. When the scanning frequency is 25 Hz, the control accuracy reaches 10-5. AFM imaging quality has been significantly improved.