基于最小二乘支持向量机的精密数控机床热误差建模与补偿研究

Thermal Error Modeling and Compensation for Precision CNC Machine Tool Based on Least Square Support Vector Machine

为了减小热误差对数控机床加工精度的影响,以自主研制的五轴精密数控机床为研究对象,得出定位误差与温度之间的变化规律。运用最小二乘支持向量机(LS-SVM)建立Y轴的热误差模型,并对LS-SVM模型进行参数寻优。根据LS-SVM模型计算出移动轴热平衡状态下定位误差的预测值与测量值对比曲线,通过分析发现LS-SVM热误差模型性能较好,其拟合偏差带宽较窄,均方差较小。依据LS-SVM模型进行定位误差补偿实验,误差降低了87. 3%。实验结果证明最小二乘支持向量机建模方法具有较高的预测精度、补偿精度。

To reduce the influence of thermal error on the machining accuracy of NC machine tools,the self-built five axis precision CNC machine tool was taken as the research object.The change rules between position error and temperature change was found out.The thermal error model of Y axes was established based on least square support vector machine(LS-SVM).The parameters of the least square support vector machine model were optimized.According to least square support vector machine thermal error model,The prediction data comparing curves of the linear axes positioning error in the thermal equilibrium state were calculated.Through analysis,the prediction accuracy of the thermal error model based on the least square support vector machine is better,the fitting bandwidth of the linear axes value is narrower,and the mean square deviation is smaller.According to the LS-SVM model,the error compensation experiment was carried out,and the error was reduced by 87.3%.The experimental results demonstrate that the least square support vector machine modeling method has high prediction accuracy and precision.