Stewart型并联机床伸缩杆伸长量误差在线测量

On-line measurement of extension errors of legs for 6-sps Stewart in-parallel machine

标定作为提高Stewart型并联机床静态精度的有效方法 ,包括建模、测量、参数识别和补偿等环节。其中伸缩杆伸长量误差的测量准确性直接影响标定效果。本文提出间接方法准确测量其值。首先选择激光跟踪系统精确测量并联机床不同位姿对应的伸缩杆绝对伸长量 ,再辅以符号运算 ,最终达到测量机床伸缩杆伸长量误差的目的。

As the effective method for improving the static accuracy of parallel machine based on the Stewart platform, calibration includes four basic steps, such as kinematic modeling, measurement, identification and compensation. The metrical errors of extension quantity of legs affect the calibration directly. To measure errors of extension quantity accurately while the legs of the parallel machine are extending, an indirect method is present. Firstly, the extension quantity corresponding with special poses is measured using the laser tracking system, then, symbolic operation is adopted to obtain the errors of extension quantity of the legs.