圆光栅测角误差实时补偿方法研究

Real-time compensation method for angle measurement error of circular grating

误差补偿是提高圆光栅测角精度的常用手段。一些机床和精密仪器由于没有位置测量元件误差补偿功能,无法进行圆光栅的误差在线补偿。针对这一问题,提出了一种中继式的圆光栅测角误差实时补偿方法。首先,分析了圆光栅测角误差的补偿原理,建立了谐波拟合函数和圆光栅测角误差补偿模型;然后,进行了误差补偿模块的硬件选型,设计了以差分芯片为核心的信号转换电路,包括差分信号转单端信号电路和单端信号转差分信号电路,开发了误差补偿模块的嵌入式软件,将所设计的误差补偿模块插入到圆光栅的信号输出通道,建立了基于中继式误差补偿模块的试验系统;最后,采用雷尼绍校准装置采集了圆光栅的原始误差数据,使用谐波函数对测角误差数据进行了拟合,应用误差补偿模型,利用误差补偿硬件模块,对圆光栅测角误差进行了在线补偿试验。研究结果表明:对测角误差最大值为134.59″的圆光栅进行补偿后,其误差最大值可减小到12.62″,可见采用误差实时补偿方法可以显著提高圆光栅测角精度。

Error compensation is a common means to improve the angle measurement accuracy of circular grating.Some machine tools and precision instruments can t compensate the error of circular grating online because they don t have the error compensation function of position measuring elements.Aiming at the problem,a relaying real-time compensation method for angle measurement error of circular grating was proposed.Firstly,the compensation principle of angle measurement error of circular grating was analyzed,harmonic fitting function and compensation model for angle measurement error of circular grating was established.Then,the hardware selection of the error compensation module was carried out,and signal conversion circuit with a differential chip as the core was designed,included a circuit for a differential signal to a single ended signal and a circuit for a single ended signal to a differential signal.The embedded software of the error compensation module was developed.The designed error compensation module was inserted into the signal output channel of the circular grating.An experimental system based on relaying error compensation module was established.Finally,the original error data of the circular grating was collected by the Renishaw calibration device,the angle measurement error data was fitted by the harmonic function,applied error compensation model,and the online compensation test of the angle measurement error of the circular grating was carried out by the hardware module of error compensation.The results indicate that after compensating the circular grating with the maximum angle measurement error of 134.59″,the maximum error decreased to 12.62″.It can be seen that the real-time error compensation method can significantly improve the angle measurement accuracy of circular grating.