Variable Parameters Model of Machine Tool Thermal Error

Due to the ambiguous influencing factors on thermal error and difficulties in determining temperature measuring points, an on-line grey GM(1,1) prediction model with variable parameters is advanced. By virtue of modeling on thermal error with single sequence, the method has no necessity to consider thermal error extraneous affecting factors. According to continuous input data, parameter iterative formula of the model can modify model constantly. The model solves the problems that conventional GM(1,1) has difficulty in predicting mass data and can not forecast nonlinear variation trend. As the iterative formula is related to the previous two points, working capacity of calculation in modeling is small and operation time is very short. We applied the variable parameters GM(1,1) in a precise horizontal machining centre to forecast spindle´s thermal error. Research shows the on-line modeling method has high predict accuracy and good robustness.