Multidrive control for milling rotary tables with flexible reduction stages

This contribution is concerned with multidrive servo control of very large rotary tables for machine tools, where flexible gears limit the achievable feedback control performance. State space control extensions, that are now available for servo axis controllers, can improve the performance significantly but increase the design and commissioning complexity. After an overview of state-of-the-art control concepts, a simplified mathematical model for efficient commissioning is derived. The design issues for successful application are discussed. The achievable performance for multidrive servo axes is elucidated by an exemplary milling machine tool rotary table.