压电式二维微动工作台的迟滞补偿与解耦控制

为了提高压电式二维微动工作台的定位精度,基于改进的Prandtl-Ishlinskii模型设计了前馈与解耦控制器,并结合反馈控制器开发了复合控制系统.在分析x与y方向电压与位移之间迟滞关系的基础上,前馈控制器通过改进的Prandtl-Ishlinskii模型描述迟滞的逆过程,分别补偿了x与y方向的迟滞.解耦控制器通过改进型Prandtl-Ishlinskii模型估算耦合位移值,修正驱动电压,抵消耦合效应引起的位移.复合控制系统结合了前馈与解耦控制器,并加入PID反馈控制进一步提高定位精度.实验结果表明:控制前,x方向与y方向定位误差的最大绝对值分别是4.16μm和4.18μm,而采用复合控制后定位误差的最大绝对值降为0.06μm和0.07μm.这种复合控制方法能够补偿压电式微动工作台的迟滞非线性,无需改变结构或更换零件就能减小耦合效应,有效地提高微动工作台定位精度.

Hysteresis Compensation and Decoupling Control of Piezoelectrically Driven Two-Dimensional Micro-Positioning Stage

To improve the accuracy of piezoelectrically driven two-dimensional micro-positioning stage, a compound control system incorporating feedforward, decoupling and feedback controllers was designed to compensate for the hysteresis of piezoelectric actuator and attenuate the coupling effect between different actuating directions. With modified Prandtl-Ishlinskii hysteresis model, two feedforward controllers were designed to compensate for the hysteresis in the x and y directions, respectively. To attenuate the cou- pling effect, the decoupling controller was used to estimated the coupling shift and then manipulate the voltage to counteract this shift. The compound control system incorporating feedforward, decoupling and PID feedback controllers to reduce the tracking error. Experimental result shows that the maximum abso- lute values of tracking error were 4. 16 p,m in the x direction and 4. 18 p,m in the y direction without con- trol, while they were reduced to 0.06 p,m and 0.07 p,m, respectively, with the compound control sys- tem. It indicates that the compound control system can well compensate for hysteresis and attenuate cou- pling effect without modifying the structure.