Theory and applications of the robust cross-coupled control design

The cross-coupled control (CCC) has been recognized as an efficient motion controller that reduces contouring errors, but theoretical analysis of it i s lacking and there is no systematic design approach for obtaining a CCC sy stem with guaranteed central performance. Consequently, the compensators C in CCC are commonly implemented in a PID structure and their contouring acc uracy is usually degraded in real applications under different operating co nditions. In an attempt to overcome the CCC design limitations described ab ove, this paper introduces a robust CCC design based on a novel formulation : the contouring error transfer function (CETF) leading to an equivalent fo rmulation as in the feedback control design problem. Then, methods in robus t control design can be readily employed to achieve robust CCC,vith specifi ed stability margins and guaranteed contouring performance. Furthermore, th e proposed design has been verified as being internally stable. All provide d experimental results indicate that the proposed robust CCC design consist ently renders satisfactory contouring accuracy under different operating co nditions.