Multivariable Iterative Learning Control Design for Precision Control of Flexible Feed Drives
Yulin Wang1,2, Tesheng Hsiao1
1Institute of Electrical and Control Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan.
Sensors (Basel, Switzerland)
|June 19, 2024
Summary
This study introduces a multivariable iterative learning control (MILC) for CNC machine tools. The method improves dynamic positioning accuracy by using motor and table feedback, enhancing precision in flexible feed drive systems.
Area of Science:
- Mechanical Engineering
- Control Systems Engineering
Background:
- Modern machining requires higher speeds and precision, driving demand for advanced control systems in CNC machine tools.
- Conventional CNC controllers use motor-side rotary encoders for position feedback to ensure stability and prevent component damage, but limitations remain.
- Factors like lead errors, vibrations, and thermal deformation impact positioning accuracy in flexible feed drive systems.
Purpose of the Study:
- To develop and validate a novel multivariable iterative learning control (MILC) method for flexible CNC feed drive systems.
- To enhance dynamic positioning accuracy by integrating feedback from both motor and table sides.
- To mitigate control conflicts and reduce tracking errors in flexible structures.
Main Methods:
- Implementation of a multivariable iterative learning control (MILC) strategy.
- Utilization of error data from both motor and table sides for enhanced precision.
- Injection of compensation commands into reference trajectory and control command via norm-optimization.
- Experimental validation on an industrial biaxial CNC machine tool.
Main Results:
- The MILC method effectively enhances dynamic positioning accuracy in flexible feed drive systems.
- Integration of dual-side feedback (motor and table) leads to superior precision.
- Conflicts between feedback control (FBC) and traditional iterative learning control (ILC) are mitigated.
- Significantly smaller tracking errors were achieved on the table side.
Conclusions:
- The proposed MILC method offers a robust solution for improving precision in CNC machine tools.
- This approach demonstrates significant potential for advancing control strategies in high-speed, high-precision machining.
- Experimental validation confirms the efficacy of MILC for industrial applications.
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