This work presents an application of a linear Kalman filter to control the effects of thermal expansion in a recirculating ball screw of a computer numerical control (CNC) machine, impacting the final position accuracy of the machining tool. Through the Kalman filter, the system’s state ball screw position is estimated iteratively, allowing for real-time compensation of thermal variations, dilation, and positional inaccuracies on machining precision. The effectiveness of the proposed approach is demonstrated through experimental validation using a dataset comprising positional and temperatures measurements. The performance of the Kalman filter was evaluated through statistical analysis and for measurements taken during the heating cycle, the Y-axis exhibited R2 of 0.913 and \({\rm R}^{2}_{\rm adj}\) of 0.906, with an RMSE of 9.32 μm, indicating a good fit of the model to the data and acceptable precision of the estimates. For the X-axis under similar thermal conditions, higher values of R2 and R2adj were obtained with a lower RMSE confirming the high accuracy of the estimates and the method.

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Dynamic Thermal Compensation in CNC Machining: Modeling a Linear Kalman Filter for Enhanced Positional Accuracy

  • Adalto de Farias,
  • Emeldo Rogelio Caballero Brochado,
  • Marcelo Otavio dos Santos,
  • Nelson Wilson Paschoalinoto,
  • Vanessa Seriacopi,
  • Ed Claudio Bordinassi

摘要

This work presents an application of a linear Kalman filter to control the effects of thermal expansion in a recirculating ball screw of a computer numerical control (CNC) machine, impacting the final position accuracy of the machining tool. Through the Kalman filter, the system’s state ball screw position is estimated iteratively, allowing for real-time compensation of thermal variations, dilation, and positional inaccuracies on machining precision. The effectiveness of the proposed approach is demonstrated through experimental validation using a dataset comprising positional and temperatures measurements. The performance of the Kalman filter was evaluated through statistical analysis and for measurements taken during the heating cycle, the Y-axis exhibited R2 of 0.913 and \({\rm R}^{2}_{\rm adj}\) of 0.906, with an RMSE of 9.32 μm, indicating a good fit of the model to the data and acceptable precision of the estimates. For the X-axis under similar thermal conditions, higher values of R2 and R2adj were obtained with a lower RMSE confirming the high accuracy of the estimates and the method.