自由曲面光学元件气囊抛光进动运动控制技术

Control Techniques of Bonnet Polishing for Free-form Optical Lenses with Precession

针对自由曲面光学元件的加工特点,研究气囊抛光自由曲面光学元件进动运动控制技术,用于求出气囊工具进动过程中两虚拟轴的转角,实现对气囊自转轴空间位置的控制。以气囊自转轴为研究对象,由于自由曲面光学元件上每个点的法线三维坐标都不相同且气囊进动抛光过程中气囊自转轴与工件加工点局部法线夹角不变,提出建立基坐标系和抛光点对应三维空间坐标系的方法,得到抛光过程中气囊自转轴的空间位置变化情况,而后利用旋转坐标变换得到气囊抛光进动运动控制模型;在所建立的自由曲面光学元件气囊抛光进动运动控制模型中加入控制算法,求出抛光自由曲面光学元件各点时气囊工具两个虚拟旋转轴的转角。利用Matlab对自由曲面光学元件不同方向截面进行仿真抛光试验,得到自由曲面各方向上气囊抛光进动运动曲线以及仿真进动角曲线,结果证明了自由曲面光学元件气囊抛光进动运动控制模型及控制算法的正确性。

Control techniques of bonnet polishing free-form optical lenses with ＇precession＇ is studied, according to the processing characters of free-form optical lenses, to figure out the rotating angles of two virtual axes of bonnet tool, which lead to the controllability of spin axis of bonnet tool. The spin axis of bonnet tool is taken as the object, due to the difference of the local normal of each polishing point and the angle between the spin axis of bonnet tool and local normal is keeping constant in polishing process, a method about how to set up basic coordinate and corresponding coordinate of polishing point is proposed, aiming to get the positions of spin axis of bonnet tool in polishing process, by which a movement model can be obtained by combining with rotating coordinate transformation; Then control algorithm is added to the movement model, and rotating angles of two virtual axes of bonnet tool when polishing each point on free-form optical lenses are calculated. At the end, simulations in polishing different directions of free-form optical lens in Matlab are carried out, to get the curves of precession control and the simulated precession angles, the results reveal that the movement model and control algorithm presented are both correct.