Investigation on feedback control of linear motors in ultraprecision-machine feed-drive systems

摘要

Linear motors offer many advantages over ac or dc servo motors. More and more ultraprecision machines use linear motors in their feed-drive systems. The distance measured by the linear encoder is used to calculate the linear motor's velocity. A linear-motor controller needs a high-resolution position sensor for smooth velocity control. However, the high-resolution position sensor may sense the vibration of the mechanical structure and therefore cause instability. This article presents a simulation model to analyze the impact of linear encoder feedback on a linear motor's motion control and stability. Experiments are designed to validate the simulation model. Both simulation and experiment demonstrate that proper selection of linear encoder's resolution can satisfy a smooth velocity control and stability requirements.