补偿压电陶瓷迟滞和蠕变的逆控制算法

研究了用于扫描探针显微镜,特别是原子力显微镜(AFM)中的扫描器高精度定位问题。压电陶瓷驱动器通常用于这种扫描器中,在无补偿的开环控制期间,它在输入电压和输出位移之间表现出明显的迟滞和蠕变。迟滞和蠕变降低了扫描器的定位精度并使扫描图像出现了畸变。给出了迟滞和蠕变模型及参数的在线辨识方法。在AFM的扫描控制中,使用基于该模型的逆控制算法补偿了压电陶瓷的迟滞和蠕变。在分析中,Preisach迟滞模型和对数蠕变模型被用于描述压电陶瓷驱动器的非线性。由于该方法不需要在控制过程中进行参数设置,因此很容易使用。此外由于是开环控制方法,可以具有更好的分辨率。闭环操作能够给出较好的迟滞和蠕变补偿,但由于在高带宽情况下传感器动态范围的限制,对于小扫描区域或样本特征,它减小了成像的分辨率。三角波轨迹跟踪的仿真结果说明轨迹误差在传感器噪声量级上,证明了这个方法的有效性。

Inverse control algorithm to compensate the hysteresis and creep effect of piezoceramic

The high-precision positioning with scanners in Scanning Probe Microscopes applications,particularly in atomic force microscopes(AFM),was studied.The piezoceramic actuators are usually used in this kind of scanner,which obviously exhibits the hysteresis and creep between the input voltages and the output displacements during the uncompensated open-loop operation.The hysteresis and creep reduce the positioning precision and produce a distortion in scanning images.A novel hysteresis and creep model was proposed,and the method that can on-line identify parameters was also provided.Furthermore,the model-based inverse control algorithm was used to compensate the hysteresis and creep effect of piezoceramic during AFM scanning.In the analysis,the Preisach hysteresis model and logarithmic creep model were used to characterize the nonlinear behavior of the piezoceramic actuator.This method is easy-to-use because it does not need set parameters in control procedure.Moreover,it has high resolution as it is an open-loop control scheme.Closed-loop operation can offer better hysteresis and creep compensation,but it can reduce image resolution for small scans/sample features due to limited dynamic range of sensors at higher bandwidth.Simulation results of tracking triangular wave trajectories show tracking error is on the magnitude of the sensor noise level,which demonstrate the validity of the method.