基于线性自抗扰控制的工件台单扫描轴应用研究

Application Research of Scanning Axis in Wafer Stage Based on Linear Active Disturbance Rejection Control

传统工件台控制需预先建立不同位置的补偿参数表,调试过程繁琐且适应性不强。针对这些问题,在某工件台改造实验中,使用基于带遗忘因子的递推最小二乘法对工件台中1个扫描轴在闭环运动条件下带额外输入的二阶自回归模型参数进行辨识,在此基础上,添加与设定轨迹有关的前馈参数,通过仿真找到控制特性适中的控制器初值,解决实物验证过程中由于没有初值无法使用线性自抗扰控制器的问题。在该初值基础上进行性能调试,优化扫描运动全行程控制误差。实验表明,根据改造后的线性自抗扰控制方案,控制器可取消与位置有关的200个补偿参数,且取消后匀速段扫描速度均匀性由原来的0.6%优化至0.22%。

In view of the traditional control in the wafer stage,the parameter of compensation table varies with positions needs to be established in advance,which brings about the problems of cumbersome debugging and weak adaptability. In a motion platform transformation experiment,the recursive least squares method with exponential forgetting was used to identify the parameters of the second-order autoregressive with extra input of a scan axis in the workpiece stage under the condition of closed-loop motion. On this basis,the parameters of feedforward related to the set trajectory are added,and the initial value of the controller with moderate control characteristics is found through simulation,which solves the problem that the linear active disturbance rejection controller cannot be used because there is no initial value in the physical verification process. Performance debugging was further performed on the basis of the initial value to optimize the control error of the full stroke of the scanning motion. Experiments have proved that using the modified linear active disturbance rejection control,the controller can cancel 200 compensation parameters related to the position,After the transformation,the uniformity of scanning speed in the uniform speed section has been improved from 0.6% to 0.22%.