Combined contour error control method for five-axis machine tools based on digital twin

Contour error is a critical factor influencing machining quality. This paper proposes a combined contour error control method for five-axis machine tools based on digital twin. The proposed method combines pre-compensation implemented in digital twin with feedback control in the real-time controller. After obtaining the tool path input, the digital twin performs interpolation and applies model predictive pre-compensation control to the interpolated commands to control modeled errors. The pre-compensated commands and interpolation data are sent to the real-time controller where contour error is estimated and controlled in each control cycle through feedback control to control unmodeled errors. Using the S-shaped curve as the test case, the maximum tool tip position contour error is reduced by 77.78%, with an average reduction of 83.90%. The maximum tool orientation contour error decreased by 79.05%, with an average reduction of 86.66%. The experimental results demonstrate that the proposed method significantly reduces tool contour error.