针对一维调焦技术的不足, 在六自由度平台的基础上提出了一种基于图像处理的三维自动调焦系统。该系统以 CMOS相机为图像传感器, 以六自由度平台为执行机构, 用计算机获取图像清晰度评价值并驱动六自由度 (6-DOF)平台做三维空间运动实现三维自动调焦。调焦实验分为两部分, 一部分为一维自动调焦闭环实验, 另一部分为三维自动调焦闭环实验。针对 X、Y、Z三轴耦合性关系, 提出一种改进的随机并行梯度下降 (SPGD)算法。实验结果表明系统闭环调焦误差小于 3%, 满足三维调焦精度要求。

In order to solve the deficiency of one-dimensional auto-focusing technology, on the basis of the Six Degrees of Freedom (6-DOF) platform, a three-dimensional auto-focusing system is proposed based on the image processing technology. The system utilizes the CMOS as an image sensor, and the 6-DOF platform as an actuator, and a computer for obtaining image definition evaluation value and driving 6-DOF platform to realize three-dimensional auto-focusing. The auto-focusing experiments have two parts, which are one-dimensional and three-dimensional auto-focusing closed-loop. According to the coupling relationship of the X-axis, Y-axis and Z-axis, a modified Stochastic Parallel Gradient Descent (SPGD) algorithm is presented. The experimental results show that the closed-loop error is below 3 percent, which meets the precision requirements for three-dimensional auto-focusing.