前馈控制算法校正相移微动台非线性运动

Feed forward control algorithm for nonlinear motion correction of phase shifting stage

压电陶瓷具有推力大,响应速度快,分辨率高和能耗低等优点,但其形变量小,所以需要位移放大机构对其形变量进行放大,实现长行程高分辨率位移。针对压电陶瓷作为驱动器,柔性铰链位移放大装置作为导向机构的相移微动台运动存在非线性问题,采用多项式模型对其位移特性进行建模,通过求解逆多项式获得使其线性运动非线性电压,利用实验对非线性运动校正结果进行验证。实验结果表明,所采用前馈控制算法可以很好的校正相移微动台非线性运动,校正后相移台在x,y方向产生的最大相移误差为4°与3.2°,满足高精度相移干涉测量对相移台相移误差要求。

Piezostack is capable of producing very large force, and it has the advantages of fast response, high resolution and low consuming, but it provides only limited displacement. Therefore the displacement amplification device is needed to amplify the deformation of the piezostack to realize long range, high resolution displacement. As for the nonlinear motion of the phase shifting stage with piezostack and flexure hinge, the polynomial model is used to describe the motion characteristic of the phase shifting stage, and the inverse function of the polynomial is solved to get the nonlinear voltage in order to correct the nonlinear motion of the stage. The experiment results indicate that the feed forward control method mentioned in this paper can correct the nonlinear motion of the stage well, the maximum phase shifting error after nonlinear correction can reach 4°and 3.2° in the x and y direction. The results satisfy the requirement of the phase shifting stage for the high precision interference metrologv.