激光跟踪仪角度采集系统设计及误差修正研究

Research on Angle Acquisition System Design and Angle Error Compensation for Laser Trackers

高精度的角度采集和测量是激光跟踪仪实现跟踪和精密测量的关键。针对激光跟踪仪中采用的圆光栅编码器,本文介绍了一种基于FPGA的数据采集系统的设计与实现方法。该采集系统分为滤波、计数、通信三大模块。数字滤波模块用于消除跟踪控制过程中跟踪头振动、抖动产生的信号干扰;计数模块实现方波脉冲的倍频、辨向及计数;通信模块实现跨时钟域的数据传输。系统通过Modelsim仿真及实验测试验证了方法的可行性与可靠性。采用谐波分析方法对角度误差进行了修正,测量误差由3.5″降低到1.5″。本文设计的角度采集系统及谐波分析误差修正方法具有一定的通用性,可广泛应用于相关领域。

The high-precision angle data acquisition is the basic premise to achieve precise tracking control and measurement for laser trackers.In this paper, adata acquisition system based on FPGA is introduced for the actual-applied circular grating encoder.The system is divided into three parts and presented in detail.The digital filtering module can filter high-frequency noise, the counting module is used to accomplish pulse counting and rotating direction discerning, and the communication module implements signals transmitting between multiple processors.The simulation by Modelsim and experimental results show that the system is able to realize correct and reliable data acquisition and transmission.The measurement error is analyzed and the harmonic error compensation method is discussed.After compensation, the error is remarkably reduced from 3.5″to 1.5″.