Motion control for linear motor feed drives in advanced machine tools

Minimum-time path optimization (MTPO) and minimum-time tracking control (MTTC) have previously been introduced as effective strategies for controlling high-speed machine tools [D. Renton, M.A. Elbestawi, High speed seruo control of multi-axis machine tools, Int. J. Machine Tools Manuf. 40 (2000) 539–559]. It has been argued that the effectiveness of these strategies is due to their ability to accommodate the dominating saturation effects in control of high-speed machine tools. In this paper the application of MTPO and MTTC to linear-motor-driven machines is examined. It is found that the attention paid to saturation limits by MTPO and MTTC strategies provides significant performance improvements for linear-motor-driven machines. Issues such as improved stiffness to periodic disturbances, improving holding torque through heat-reducing commutation methods and improved sensor feedback are also examined.