Improvement of the Performance in Machine Tools by Means of State Space Control Strategies

This paper describes new control techniques based on state space observers that have been developed to improve the precision and dynamic behaviour of machine tools. To improve precision, the position of the tool centre point (TCP) is estimated and used as position feedback instead of the position of the slides. Dynamic behaviour is improved by estimating the acceleration of the TCP and feeding this noiseless signal into the control system. These techniques provide a simple way to achieve considerable improvements without using complex and expensive TCP position measurement devices. Tests on actual machines have shown that errors produced by deflections between the slide and the TCP can be reduced by 70%.