Feedforward and feedback strategies applying the principle of input balancing for minimal tracking errors in CNC machine tools

In high-precision machine tools only very small deviations of the tool from the reference contour are admitted. In order to satisfy the accuracy requirements, three control goals have to be attained. Firstly, a smallest possible tracking error of every feed axis has to be attained. Secondly, a nearly identical dynamic performance of the axes is advantageous, because then the contour error is nearly zero, though each axis may have the same considerable tracking error. Thirdly, the suppression of nonperiodic or periodic disturbances is a crucial demand. In this contribution different feedforward and feedback strategies for cascade control structures are discussed and compared with polynomial controllers available on the market. A new issue is the principle of input balancing.