高速、高精度数控伺服工作台摩擦误差的研究

建立了一种考虑摩擦影响的PID控制下的高速、高精度进给伺服工作台的数学模型。伺服机构中的摩擦力是采用一种“两维混合摩擦模型”来描述的。该模型可以根据滑动速度、表面接触物体的油膜厚度等计算摩擦力。通过数值仿真与实际测量 ,在大范围的工况下 ,研究了圆运动过象限时出现凸起的误差现象。通过计算与试验结果的比较 ,证明了提出的考虑摩擦影响的数学模型能够精确地模拟PID控制下的高速、高精度进给伺服工作台的动力学过程 ,能够正确地预测进给运动过程中摩擦误差大小及特征。

STUDY ON FRICTION ERROR OF HIGH-SPEED HIGH-PRECISION NC SERVO TABLE

With consideration of friction influence, a mathematics model is established for a high-speed high-precision feed servo table under PID control. A two-component mixed friction model is used to express the friction force in servo mechanisms. The friction can be calculated according to the sliding speed, the oil film between the two contact surfaces by using the model. Under various work conditions, the protrusion error occurring at the quadrant boundary in the circular motion is profoundly studied through numerical simulation and experiments and the phenomena that the quadrant protrusion error lags with the rising of the feedrate is discovered. Comparisons between simulation results and experimental results demonstrate that with the mathematics model considering the friction effects proposed, the dynamics of high-speed high-precision servo feed systems under PID control can be accurately simulated, the friction error and its characteristics in the course of the feeding can be precisely predicted.