激光跟踪仪精密跟踪系统的设计

Design of precise tracking system of laser tracker

对激光跟踪仪的跟踪伺服控制系统进行了整体研究并给出了总体设计方案。针对跟踪目标的精密探测问题,研究了新型探测手段以及微弱光电信号的精细调理技术与数字滤波方法,使得脱靶量探测稳定性优于±2.0μm。针对跟踪角度精密测量问题,设计了圆光栅数据采集系统,实现了角度脉冲的细分、辨向与准确计数;基于谐波分析方法建立了跟踪过程中的误差补偿模型,将角度测量精度由3.5″提高到1.5″。建立了跟踪伺服电机的数学模型,分析了电流环在跟踪控制中的作用机理,提出了电流、速度、位置三闭环控制结构和复合跟踪控制策略。跟踪实验表明:系统最远跟踪距离不小于41.7m,跟踪速度不低于2.0m/s。该项技术还能为空间动态目标跟踪、激光通信等提供有益借鉴。

This paper focuses on the total research of tracking servo control system of a laser tracker and gives a total design scheme. For precise detection of the miss-distance of a tracking target, new detection methods, fine adjusting technologies and digital filtering methods for weak photoelectric signals were explored, by which the detection stability for miss-distance of the tracking target could be better than ~ 2.0 μm. To measure precisely tracking angles, a circular grating data acquisition system was designed, and the digital filtering, angle subdivision and accurate counting as well as data communication modules were achieved. According to the angle data, a tracking error compensation model was established based on harmonic analysis method, and the angle measurement precision was improved to 1.5＂ from 3.5＂. For tracking servo motor, a mathematical model was established to analyze the special function of current loop in tracking control process, then a three-closed-loop control structure including the current, speed, position and a compound tracking control strategy was proposed. The tracking experiment shows that the tracking distance and the tracking speed are not less than 41.7 m and 2.0 m/s respectively. The technology can also provide a useful reference for the dynamic target tracking, laser communication and so on.