Flatness-Based Trajectory Tracking Control of a Rotating Shaft

ontrol of a magnetically levitated shaft used for drilling non-circular holes is considered. For this drilling process the shaft position must track a given reference trajectory determining the shape of the hole. The flatness property of the shaft model simplifies the design of a tracking controller. The system state as well as certain disturbances (due to model inaccuracies and drilling forces) are estimated by means of an observer. The usefulness of the proposed flatness-based trajectory tracking controller is demonstrated by experimental results obtained with a spindle built at the German company AXOMAT, Berggießhübel.